Patent Publication Number: US-8523765-B2

Title: Medical control apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of PCT/JP2006/314398 filed on Jul. 20, 2006 and claims the benefit of Japanese Applications No. 2005-214726 filed in Japan on Jul. 25, 2005, No. 2005-214727 filed in Japan on Jul. 25, 2005, No. 2005-214728 filed in Japan on Jul. 25, 2005 and No. 2005-214729 filed in Japan on Jul. 25, 2005 the entire contents of each of which are incorporated herein by their reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a medical control apparatus that controls driving section for causing a bending portion of a medical device to perform bending movements. 
     2. Description of the Related Art 
     Conventionally, endoscopes are widely used as medical devices. Such an endoscope is equipped with an elongated insertion portion, and by inserting the insertion portion into a body cavity, an operator is able to observe internal organs inside the body cavity or perform various therapeutic treatment using, as required, a treatment instrument inserted through a treatment instrument channel. In addition, with an endoscope applied to industrial fields, by inserting an elongated insertion portion, a worker is able to observe and examine flaws or corrosion inside a boiler, a turbine, an engine, a chemical plant or the like. 
     With such an endoscope, a bendable bending portion is provided on a proximal end-side of a distal end portion of an insertion portion. When using the endoscope, a user such as an operator operates bending operation inputting section such as a bending operation lever provided at an operation section to input an instruction on a bending direction or a bending speed of a bending portion as a bending quantity to bending driving section that causes bending movements of the bending portion. 
     Consequently, based on the bending quantity from the bending operation lever, the bending driving section causes a bending movement of the bending portion by mechanically pulling or relaxing a bending operation wire connected to a bending piece constituting the bending portion. 
     This type of a conventional endoscope includes an endoscope employing an electrical bending driving system or, in other words, an electric bending endoscope in which rotational movement of a motor built into the inside of the endoscope as bending driving section is electrically controlled, whereby the driving force of the motor pulls or relaxes a bending operation wire to cause bending movements of the bending portion. 
     For example, disclosed in Japanese Patent No. 2917263 is a technique regarding control section and the like in an electric bending endoscope, which includes a pulley that pulls the bending operation wire and which enables a torque of a motor corresponding to the pulley to be set so as to conform to the type of the insertion portion of the endoscope. 
     In addition, disclosed in Japanese Patent No. 2845255 is a technique regarding a bending operation apparatus of an electric bending endoscope, which is capable of equalizing load applied to a motor across an entire operation range of a bending portion. 
     SUMMARY OF THE INVENTION 
     The present invention comprises: a medical device having a bending portion in which a plurality of link members is respectively consecutively provided so as to be rotationally movable on a distal end-side of an insertion portion to be inserted into a subject to be examined; driving section for causing bending movements of the bending portion by respectively rotationally moving the plurality of link members; designating section that designates at least any one of the link members among the plurality of link members and designates a position and a direction of the link member; and control section that computes respective angles of the plurality of link members so that when the bending portion of the medical device moves, a position and a direction designated by the designating section are maintained when the link member designated by the designating section as well as other link members contiguous to the link member pass the position, and based on the computation results, controls the driving section to rotationally move the plurality of link members. 
     In addition, the present invention comprises: a medical device having a bending portion in which a plurality of link members is respectively consecutively provided so as to be rotationally movable on a distal end-side of an insertion portion to be inserted into a subject to be examined; driving section for causing bending movements of the bending portion by respectively rotationally moving the plurality of link members; designating section that designates a spatial angle formed by a most distal end-side link member of the insertion portion and a link member connected to the most distal end-side link member among the plurality of link members; and control section that controls the driving section to rotationally move the plurality of link members so that the spatial angle formed by the most distal end-side link member and the link member connected to the most distal end-side link member migrates from the distal end-side towards a proximal end-side so as to sequentially assume angles formed by adjacent link members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  relates to a first embodiment of the present invention and is a system configuration diagram of an endoscope apparatus configured using a medical control apparatus; 
         FIG. 2  relates to a first embodiment of the present invention and is a block diagram showing an electrical configuration of major components of the endoscope apparatus; 
         FIG. 3  relates to a first embodiment of the present invention and is a layout diagram presenting a perspective view of a substantial part of an insertion portion driving mechanism seen from a distal end-side of the insertion portion; 
         FIG. 4  relates to a first embodiment of the present invention and is a layout diagram showing the substantial part of the insertion portion driving mechanism; 
         FIG. 5  relates to a first embodiment of the present invention and is a schematic configuration diagram of a bending portion whose driving mechanism is constituted by a motor and a gear; 
         FIG. 6  relates to a first embodiment of the present invention and is a schematic configuration diagram showing a first variation of the bending portion shown in  FIG. 5 ; 
         FIG. 7  relates to a first embodiment of the present invention and is a schematic configuration diagram showing a second variation of the bending portion shown in  FIG. 5 ; 
         FIG. 8  relates to a first embodiment of the present invention and is a perspective view showing a connection configuration of a motor and a flexible shaft; 
         FIG. 9  relates to a first embodiment of the present invention and is a control block diagram of a substantial part including a controller, a driving section and the insertion portion driving mechanism section; 
         FIG. 10  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of the command control section and the actuator control block shown in  FIG. 9 ; 
         FIG. 11  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of the actuator control block; 
         FIG. 12  relates to a first embodiment of the present invention and is a block line diagram of the servo controller shown in  FIG. 11 ; 
         FIG. 13  relates to a first embodiment of the present invention and is an explanatory diagram showing a state in which a distal end portion-side link member assumes a predetermined distal end position and an attitude vector; 
         FIG. 14  relates to a first embodiment of the present invention and is an explanatory diagram showing states of other link members which are anticipated when the link member shown in  FIG. 13  is in the attitude state shown therein; 
         FIG. 15  relates to a first embodiment of the present invention and is an explanatory diagram showing a state of a predetermined position and an attitude vector when attitude control is independently performed on only the distal end portion-side link member; 
         FIG. 16  relates to a first embodiment of the present invention and is a block diagram showing a schematic configuration of a servo controller; 
         FIG. 17  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of the control law computing section shown in  FIG. 16 ; 
         FIG. 18  relates to a first embodiment of the present invention and is a block diagram showing a schematic configuration of the dynamics computing section shown in  FIG. 17 ; 
         FIG. 19  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of the dynamics computing section shown in  FIG. 18 ; 
         FIG. 20  relates to a first embodiment of the present invention and is a block diagram showing a schematic configuration of the kinematics computing section shown in  FIG. 17 ; 
         FIG. 21  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of the kinematics computing section shown in  FIG. 20 ; 
         FIG. 22  relates to a first embodiment of the present invention and is an explanatory diagram showing physical properties of an insertion portion upon insertion of the same; 
         FIG. 23  relates to a first embodiment of the present invention and is an explanatory diagram showing attitude states of other link members when a distal end-side link is fixed; 
         FIG. 24  relates to a first embodiment of the present invention and is a graph showing an example of a weighting function that is a coefficient for obtaining an optimum joint torque command value signal; 
         FIG. 25  relates to a first embodiment of the present invention and is a graph showing characteristics of a first variation of the weighting function; 
         FIG. 26  relates to a first embodiment of the present invention and is a graph showing characteristics of a second variation of the weighting function; 
         FIG. 27  relates to a first embodiment of the present invention and is a graph showing characteristics of a third variation of the weighting function; 
         FIG. 28  relates to a first embodiment of the present invention and is a graph showing characteristics of a fourth variation of the weighting function; 
         FIG. 29  relates to a first embodiment of the present invention and is a graph showing characteristics of a fifth variation of the weighting function; 
         FIG. 30  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of a controller  5  of an endoscope apparatus  1 ; 
         FIG. 31  relates to a first embodiment of the present invention and is an explanatory diagram for explaining attitude control of an insertion portion driving mechanism section and which shows a state in which a distal end-side link member is point-locked; 
         FIG. 32  relates to a first embodiment of the present invention and is an explanatory diagram showing a state in which point-locking the distal end-side link member provides a subsequent-stage link member with redundancy; 
         FIG. 33  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of the point lock computing section shown in  FIG. 30 ; 
         FIG. 34  relates to a first embodiment of the present invention and is a block diagram showing a specific configuration of the inverse kinematics computing section shown in  FIG. 33 ; 
         FIG. 35  relates to a first embodiment of the present invention and is a diagram explaining attitude control when only the distal end-side link member is point-locked; 
         FIG. 36  relates to a first embodiment of the present invention and is an explanatory diagram explaining attitude control when a fourth link member is further point-locked; 
         FIG. 37  relates to a first embodiment of the present invention and is an explanatory diagram explaining attitude control in a case where two locations are point-locked; 
         FIG. 38  relates to a first embodiment of the present invention and is a block diagram showing an internal configuration of a controller in which a point lock computing section is provided at each link member  12 ; 
         FIG. 39  relates to a first embodiment of the present invention and is a block diagram showing a configuration of a control law computing section provided with driving shaft setting section and driving shaft recognizing section; 
         FIG. 40  relates to a first embodiment of the present invention and is a block line diagram of a servo controller including an offset command inputting section; 
         FIG. 41  relates to a first embodiment of the present invention and is a block diagram showing a servo controller in the case where the same is constituted by a combination of the driving shaft setting section and the driving shaft recognizing section shown in  FIG. 39  and the offset command inputting section shown in  FIG. 40 ; 
         FIG. 42  relates to a second embodiment of the present invention and is a schematic configuration diagram showing a configuration of an insertion portion driving mechanism in which a load detecting section for detecting a load generated by coming into contact with an intestinal wall is provided at each link member; 
         FIG. 43  relates to a second embodiment of the present invention and is a block diagram showing a dynamics computing section included in the load detecting section shown in  FIG. 42  and a control law computing section  36 B; 
         FIG. 44  relates to a second embodiment of the present invention and is a graph showing characteristics of a detection result from the load detecting section and a coefficient that determines a weighting function; 
         FIG. 45  relates to a second embodiment of the present invention and is a graph showing an example of characteristics that differs from those shown in  FIG. 44 ; 
         FIG. 46  represents a first variation of the second embodiment and is a graph showing characteristics of a detection result from the load detecting section and time; 
         FIG. 47  is a block diagram showing a substantial block configuration for implementing the first variation of the second embodiment; 
         FIG. 48  represents a second variation of the second embodiment and is a graph showing characteristics of a detection result from a displacement sensor used as a load detecting section and time; 
         FIG. 49  is a block diagram showing a substantial block configuration for implementing the second variation of the second embodiment; 
         FIG. 50  relates to a third embodiment of the present invention and is a top view showing a configuration of a bending portion whose driving mechanism is constituted by a bending operation wire, a driving pulley and a free pulley; 
         FIG. 51  relates to the third embodiment of the present invention and is a side view showing a suspended state of a bending operation wire provided between respective link members of the bending portion shown in  FIG. 50 ; 
         FIG. 52  relates to the third embodiment of the present invention and is a configuration diagram showing a configuration of a driving pulley provided with the driving shaft shown in  FIG. 50 ; 
         FIG. 53  relates to the third embodiment of the present invention and is a top view showing a configuration of the free pulley shown in  FIG. 50 ; 
         FIG. 54  relates to the third embodiment of the present invention and is an explanatory diagram for explaining problem areas of a case where bending movements of a link member is performed by pulling or relaxing the bending operation wire, and shows a state when a plurality of link members is not performing bending movements; 
         FIG. 55  relates to the third embodiment of the present invention and is a diagram showing a state in which the distal end-side link member inadvertently bends due to interference when a second-stage link member is bent by 90 degrees; 
         FIG. 56  relates to the third embodiment of the present invention and is a graph showing characteristics of a detection result from the load detecting section and a coefficient that determines a weighting function; 
         FIG. 57  relates to the third embodiment of the present invention and is a diagram showing a state in which a controller according to the present embodiment performs correction control so as to bend the distal end-side link member by 90 degrees in an opposite direction from the state shown in  FIG. 55 ; 
         FIG. 58  relates to a fourth embodiment of the present invention and is a configuration diagram showing a configuration of an entire endoscope apparatus; 
         FIG. 59  relates to the fourth embodiment of the present invention and is an explanatory diagram explaining characteristics of a bending portion when bending driving is performed thereon by a controller; 
         FIG. 60  is an explanatory diagram explaining characteristics of a bending portion when stiffness control is performed thereon by a controller according to the fourth embodiment; 
         FIG. 61  relates to a first variation of the fourth embodiment and is a configuration diagram showing a configuration of an entire endoscope apparatus; 
         FIG. 62  relates to the first variation of the fourth embodiment and is a block diagram showing a specific internal configuration of a servo controller; 
         FIG. 63  relates to the first variation of the fourth embodiment and is an explanatory diagram explaining characteristics of a bending portion when stiffness control is performed thereon by a controller; 
         FIG. 64  relates to the first variation of the fourth embodiment and is a block line diagram showing the bending control section shown in  FIG. 62 ; 
         FIG. 65  relates to the first variation of the fourth embodiment and is a block line diagram showing the control section for stiffness control shown in  FIG. 62 ; 
         FIG. 66  relates to a second variation of the fourth embodiment and is a configuration diagram showing a configuration of an entire endoscope apparatus according to the second variation; 
         FIG. 67  relates to the second variation of the fourth embodiment and is an explanatory diagram explaining characteristics of a bending portion when stiffness control is performed thereon by a controller; 
         FIG. 68A  relates to the second variation of the fourth embodiment and is a principle diagram of a bending portion for explaining effects; 
         FIG. 68B  relates to the second variation of the fourth embodiment and is an explanatory diagram showing a state in which slack has occurred at a wire due to the shortening of tortuous tube length as a result of the pulling of a wire at a first bending portion; 
         FIG. 68C  relates to the second variation of the fourth embodiment and is an explanatory diagram showing a state in which slack has occurred at a wire due to the shortening of tortuous tube length of a second bending portion as a result of the pulling of a wire at the second bending portion; 
         FIG. 69  relates to the second variation of the fourth embodiment and is a block line diagram showing a control section; 
         FIG. 70  relates to a fifth embodiment of the present invention and is a block diagram showing a kinematics computing section included in a servo controller; 
         FIG. 71  relates to the fifth embodiment of the present invention and is a block diagram showing an overall configuration of a servo controller provided at each actuator control block, according to the fifth embodiment of the present invention; 
         FIG. 72  relates to the fifth embodiment of the present invention and is a block line diagram of the control block shown in  FIG. 71 ; 
         FIG. 73  relates to the fifth embodiment of the present invention and is a block diagram showing a specific configuration of the control block shown in  FIG. 71 ; 
         FIG. 74  is a block diagram showing a first variation of the fifth embodiment; 
         FIG. 75  is a block diagram showing a second variation of the fifth embodiment; 
         FIG. 76  relates to the second variation of the fifth embodiment of the present invention and is a block diagram showing a specific configuration of the operation quantity change detecting section shown in  FIG. 75 ; 
         FIG. 77  relates to the second variation of the fifth embodiment of the present invention and is a block diagram showing a configuration in which a blind bandwidth setting section is provided at the operation quantity change detecting section shown in  FIG. 75 ; 
         FIG. 78  relates to a sixth embodiment of the present invention and is a block diagram showing an overall configuration of a servo controller provided at each actuator control block; 
         FIG. 79  relates to the sixth embodiment of the present invention and is a graph showing characteristics of gain and frequency of an input/output signal of the control block shown in  FIG. 78 ; 
         FIG. 80  relates to the sixth embodiment of the present invention and is a graph showing characteristics of phase and frequency of an input/output signal of the control block shown in  FIG. 78 ; 
         FIG. 81  relates to the sixth embodiment of the present invention and is a diagram showing a state in which an extremum and a zero point on a real axis of a complex open plane are set to be symmetrical with respect to an imaginary axis; 
         FIG. 82  relates to the sixth embodiment of the present invention and is a diagram showing a state in which extrema and zero points on positive and negative real axes of a complex open plane are set to be symmetrical with respect to an imaginary axis; 
         FIG. 83  relates to the sixth embodiment of the present invention and is a block diagram showing a filter section included in the first control block shown in  FIG. 78 ; 
         FIG. 84  is a block diagram showing a first variation of the sixth embodiment; 
         FIG. 85  is a block diagram showing a second variation of the sixth embodiment; 
         FIG. 86  relates to a seventh embodiment of the present invention and is a block diagram showing an overall configuration of a servo controller provided at each actuator control block; 
         FIG. 87  represents a variation of the seventh embodiment and is a block diagram showing an overall configuration of a servo controller provided with setting section for setting a shift pathway; 
         FIG. 88  relates to the variation of the seventh embodiment of the present invention and is an explanatory diagram for explaining channels settable by the channel setting section shown in  FIG. 87 , according to the variation of the seventh embodiment; 
         FIG. 89  relates to the variation of the seventh embodiment of the present invention and is a diagram showing an example of an input/output signal of the channel setting section; 
         FIG. 90  relates to the variation of the seventh embodiment of the present invention and is a diagram showing a replacement matrix to be used during channel setting by the channel setting section; 
         FIG. 91  relates to the variation of the seventh embodiment of the present invention and is a diagram showing an example of a channel setting set by the channel setting section; 
         FIG. 92  is an explanatory diagram for explaining basic shifting control according to the fourth embodiment of the present invention; 
         FIG. 93  relates to an eighth embodiment and is an explanatory diagram for explaining shifting control based on relative displacement; 
         FIG. 94  relates to the eighth embodiment and is a block diagram showing an overall configuration of a servo controller provided at each actuator control block; 
         FIG. 95  relates to the eighth embodiment and is a block diagram showing a specific configuration of the relative displacement converting section shown in  FIG. 94 ; 
         FIG. 96  represents a first variation of the eighth embodiment and is an explanatory diagram for explaining another shifting control based on relative displacement; and 
         FIG. 97  is a block diagram showing a second variation of the eighth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be described below with reference to the drawings. 
       FIGS. 1 to 29  are for describing a basic configuration of a medical control apparatus according to a first embodiment of the present invention, wherein  FIG. 1  is a system configuration diagram of an endoscope apparatus configured using the medical control apparatus. 
     As shown in  FIG. 1 , an endoscope apparatus  1  using a medical control apparatus according to the present invention comprises image pickup section, not shown, in a distal end portion of an insertion portion thereof, and further includes: an electronic endoscope (hereinafter, simply endoscope)  2  as a medical device provided with a driving section  10   b  for bending a bending portion  14  of an insertion portion  9 , to be described later, either in an operation section  10  or in the bending portion  14 ; a light source  3  detachably connected to the endoscope  2  and which supplies illumination light thereto; a video processor  4  detachably connected to the endoscope  2 , and which controls the image pickup section of the endoscope  2  and also processes a signal obtained from the image pickup section to output a standard video signal; a controller  5  either provided in the video processor  4  or provided separately therefrom, and which controls the driving section  10   b  of the endoscope  2  so that bending movements of the bending portion  14  are performed; a monitor  6  that displays an endoscopic image obtained through signal processing performed by the video processor  4 ; an operation command section  7  as designating section to be electrically connected to the controller  5 ; and a setting value command section  8  as setting value inputting section electrically connected to the controller  5 . 
     Although not shown, the video processor  4  is arranged so that a VTR deck, a video printer, a video disk, an image file recording device or the like is connectable thereto. 
     The endoscope  2  includes: an elongated insertion portion  9  to be inserted into an observation object part; a grasping portion  10  consecutively provided at a proximal end portion of the insertion portion  9  and having an operation section  10   a  such as a video switch, an air/water supplying switch or the like; a universal cord  11  which is provided so as to extend from a lateral face of the grasping portion  10  and incorporates a signal cable to be connected to the image pickup section, not shown, or a light guide for transmitting illumination light, or the like; and a connector section  12  which is provided at an end portion of the universal cord  11  and detachably to be connected to the light source  3  and the video processor  4 . 
     The insertion portion  9  is constituted such that: a distal end portion  13  provided at a distal end thereof; a bendable bending portion  14  provided posteriorly (the distal end-side of the insertion portion  9  to be inserted into a subject to be examined) to the distal end portion  13 ; and a long and flexible tube portion  15  which is provided posteriorly to the bending portion  14  and formed by a soft tubular member, are consecutively provided. 
     The distal end portion  13  is constituted such that: an image pickup section, as image pickup section, into which is incorporated a solid state image pickup device, not shown, such as a CCD, a circuit board for driving the solid state image pickup device, and the like; a light guide, not shown, that transmits illumination light for illuminating an observation object part inside a body cavity, and the like, are incorporated therein. A configuration of the bending portion  14  will be described later. 
     The operation command section  7  is electrically connected to the controller  5  via a connecting wire  7   b . The operation command section  7  is configured so as to include, for example, a joystick  7   a , and by operating the joystick  7   a , an operation command value signal for causing the bending portion  14  to perform a bending movement is outputted. 
     The setting value command section  8  is also electrically connected to the controller  5  via a connecting wire  8   b . The setting value command section  8  is configured so as to include, for example, a keyboard  8   a , and through key operations performed at the keyboard  8   a , various setting values necessary for bending the bending portion  14  is inputted to the controller  5 . 
     Next, a configuration of the bending portion  14  will be described with reference to  FIGS. 3 to 8 . For simplicity, the description of the bending portion  14  will be made on the assumption that the bending portion  14  is handled as a planar movement driving section (two-dimensional planar movement). 
       FIGS. 3 and 4  are for describing a schematic configuration of a distal end-side of an insertion portion including a bending portion having a driving mechanism with a link structure, wherein  FIG. 3  is a layout diagram presenting a perspective view of a substantial part of the insertion portion driving mechanism from a distal end-side of the insertion portion, and  FIG. 4  is a layout diagram showing a substantial part of the insertion portion driving mechanism. In addition:  FIG. 5  is a schematic configuration diagram of a bending portion whose driving mechanism is constituted by a motor and a gear;  FIG. 6  is a schematic configuration diagram showing a first variation of the bending portion shown in  FIG. 5 ;  FIG. 7  is a schematic configuration diagram showing a second variation of the bending portion shown in  FIG. 5 ; and  FIG. 8  is a perspective view showing a connection configuration of a motor and a flexible shaft. 
     As shown in  FIGS. 3 and 4 , the bending portion  14  is provided at the distal end-side of the insertion portion  9  to be inserted into a subject to be examined. The bending portion  14  has an insertion portion driving mechanism  20  configured so that a plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an  (where n is a natural number) is consecutively connected so as to be respectively rotationally movable by a plurality of joint members  21   b   1 ,  21   b   2 ,  21   b   3 , . . . ,  21   bn . In other words, the insertion portion driving mechanism  20  has a multi-joint link structure. 
     The driving section  10   b  is constituted by a motor  27  (refer to  FIGS. 5 and 8 ) that is a driving source for respectively rotationally moving the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an.    
     In the case where the motor  27  that is the driving section  10   b  is provided in the operation section  10 , as shown in  FIG. 8 , a flexible shaft  30  is connected via a joint  30   a  to a driving shaft  27   a  of the motor  27 . Although not shown, the flexible shaft  30  is provided so as to extend in the insertion portion  9 , and a proximal end portion thereof is connected to the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an . Consequently, the rotational force of each motor  27  is arranged to be respectively transmitted to the plurality of link members  21  via the flexible shaft  30 . 
     In addition, in the case where the motor  27  that is the driving section  10   b  is provided in the bending portion  14  of the insertion portion  9 , as shown in  FIG. 5 , the motor  27  is respectively disposed in the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an  constituting the insertion portion driving mechanism  20 . The rotational force of each motor  27  is arranged to be respectively transmitted to the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an  by a connecting gear unit  26  or the like to be connected to the motor  27 . 
     The numbers of the link members  21   a  and the joint members  21   b  are not limited to the configuration examples shown in the drawings, and configurations are also possible wherein the numbers thereof are increased or decreased in accordance with the intended use of the endoscope  2 . The link member  21   a   1  is disposed on a most distal end-side of the distal end portion  13 , and is arranged so that link members  21   a   2 ,  21   a   3 , . . . ,  21   an  are sequentially connected to a rear end-side thereof. In association therewith, the joint members  21   b   1 ,  21   b   2 ,  21   b   3 , . . . ,  21   bn  are also respectively disposed between the link members  21   a  in sequence from the distal end portion  13  side. 
     A specific configuration of the bending portion  14  is shown in  FIG. 5 . 
     As shown in  FIG. 5 , in the insertion portion driving mechanism  20  of the bending portion  14 , the motor  27  that is the driving section  10   b  is respectively disposed in the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an.    
     The plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an  is respectively connected by joint shafts  22  that are the joint members  21   b   1 ,  21   b   2 ,  21   b   3 , . . . ,  21   bn  so as to be rotationally movable. The joint shafts  22  are shaft members, and a potentiometer  23  as first detecting section is respectively mounted on the joint shafts  22 . 
     The potentiometer  23  is arranged to detect a rotational quantity of the joint shaft  22  and output the same as a state quantity detection signal of the link member  21   a  to the controller  5  via a signal wire, not shown. 
     A gear  24  that fixes the joint shaft  22  so as to be rotationally movable is respectively fixed to each proximal end-side of the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an . A gear  25  securely fixed to a shaft  26   a  of the connecting gear unit  26  meshes with the gear  24 . In other words, the connecting gear unit  26  is connected to a driving shaft, not shown, of the motor  27  provided at each of the link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an . The rotational force of the driving shaft is arranged to be transmitted to the gear  25  via the shaft  26   a.    
     Consequently, the rotational force of the motor  27  is transmitted to the gear  24  via the shaft  26   a  of the connecting gear unit  26  and the gear  25 , thereby enabling the link member  21   a  to which the gear  24  is fixed to rotationally move in a predetermined direction. 
     Since the bending portion  14  shown in  FIG. 5  includes, for each link member  21   a , the motor  27 , the connecting gear unit  26  and the gears  24  and  25  which constitute the insertion portion driving mechanism  20 , by performing rotational control of the motor  27  of a designated link member  21   a  among the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3 , . . . ,  21   an , it is possible to cause rotational movement of only the designated link member  21   a.    
     In the present embodiment, the driving mechanism  20  of the bending portion  14  may be configured like the first variation shown in  FIG. 6  or the second variation shown in  FIG. 7 . The above-mentioned first and second variations of the bending portion  14  will now be described with reference to  FIGS. 6 and 7 . 
     Unlike the bending portion  14  shown in  FIG. 5 , with the bending portion  14  according to the first and second variations, instead of providing a motor  27  at each link member  21   a , a plurality of motors  27  that is the driving section  10   b  is provided in the operation section  10 . Flexible shafts  30  are respectively connected to driving shafts  30   b  of the motors  27  via joints  30   a . The respective flexible shafts  30  are provided so as to extend in the insertion portion  9 , and are respectively connected to the link members  21   a ,  21   b ,  21   c , . . . ,  21   n . The rotational force of the motors  27  is arranged to be respectively transmitted to the plurality of link members  21   a ,  21   b ,  21   c ,  21   n  via corresponding flexible shafts  30 . 
     As shown in  FIG. 6 , while the configuration of the bending portion  14  according to the first variation is approximately the same as the insertion portion driving mechanism  20  shown in  FIG. 5 , a gear  29  is provided at a distal end-side of a flexible shaft  30  provided at each link member  21   a  so as to extend therefrom. 
     A connecting gear  28  meshes with the gear  29 . The connecting gear  28  is internally mounted in the link member  21   a , and a gear  25  is securely fixed to the side of the connecting gear  28  that is opposite to the shaft  29   a . The rotational force from the flexible shaft  30  is transmitted to the gear  24  via the gear  25 . 
     Consequently, the rotational force of the motor  27  is transmitted to the gear  24  via the driving shaft  30   b , the joint  30   a , the flexible shaft  30 , the gear  29 , the connecting gear  28 , the shaft  29   a  and the gear  25 , thereby enabling the link member  21   a  to which the gear  24  is fixed to rotationally move in a predetermined direction. 
     In the same manner as the bending portion  14  shown in  FIG. 5 , since the bending portion  14  according to the first variation includes, for each link member  21   a , the flexible shaft  30 , the connecting gear  28  and the gears  24  and  25  which constitute the insertion portion driving mechanism  20 , by performing rotational control of the motor  27  of a designated link member  21   a  among the plurality of link members  21   a   1  to  21   an , it is possible to cause rotational movement of the designated link member  21   a.    
     As shown in  FIG. 7 , while the configuration of the bending portion  14  according to the second variation is approximately the same as the insertion portion driving mechanism  20  according to the first variation, the connecting gear  28  has been removed and the flexible shaft  30  provided at each link member  21   a  so as to extend therefrom is now disposed inside each link member  21   a.    
     The gear  25  is provided on the distal end-side of the flexible shaft  30 . Therefore, the rotational force from the flexible shaft  30  is arranged to be directly transmitted to the gear  24  fixed to the rear end-side of each link member  21   a  via the gear  25  without having to travel through a connecting member such as the connecting gear  28 . Consequently, in the same manner as in the first variation, it is possible to rotationally move the link member  21   a  to which the gear  24  is fixed in a predetermined direction. 
     In the same manner as with the first variation, since the bending portion  14  according to the second variation includes, for each link member  21   a , the flexible shaft  30  and the gears  24  and  25  which constitute the insertion portion driving mechanism  20 , by performing rotational control of the motor  27  of a designated link member  21   a  among the plurality of link members  21   a   1  to  21   an , it is possible to cause rotational movement of only the designated link member  21   a.    
     Next, an electrical main configuration of the endoscope apparatus  1  comprising the endoscope  2  having such a bending portion  14  will be described with reference to  FIG. 2 . 
       FIG. 2  is a block diagram showing an electrical configuration of major components of the endoscope apparatus  1 . 
     As shown in  FIG. 2 , a primary part of the endoscope apparatus  1  is constituted by: an operation command section  7  as operation section and designating section constituted using, for example, a joystick  7   a ; a setting value command section  8  as setting value inputting section constituted using a keyboard  8   a ; a controller  5  that outputs a driving command value signal for controlling the driving section  10   b  based on an operation command value signal from the operation command section  7 , a setting value set by the setting value command section  8  and a state quantity detection signal from the potentiometer  23  or the like; driving sections  10   b  that are the motors  27  or the like that are respectively rotationally controlled based on the driving command value signal from the controller  5 ; and the insertion portion driving mechanism  20  provided in the bending portion  14  on which attitude control is performed by the rotational force of the driving section  10   b.    
     The operation command section  7  is operation section for instructing bending of the bending portion  14  using the joystick  7   a , and outputs an operation command value signal based on operation to the controller  5 . The operation command section  7  is also designating section that designates a link member  21   a  whose two-dimensional position and direction is to be fixed among the plurality of link members  21   a   1  to  21   an  constituting the bending portion  14 , and outputs the operation command value signal based on the operation to the controller  5 . 
     A control block diagram of a substantial part having the controller  5 , the driving section  10   b  and the insertion portion driving mechanism  20  is shown in  FIG. 9 . 
     As shown in  FIG. 9 , the controller  5  (refer to  FIG. 2 ) includes a command control section  5 A. The command control section  5 A is arranged so that an operation command value signal from the operation command section  7  is supplied thereto. 
     Based on a supplied operation command value signal and state quantity detection signal, the command control section  5 A performs computational processing or the like required to control the driving section  10   b  provided at an actuator control block  31 . 
     A plurality of first, second, . . . , nth actuator control blocks  31   a   1  to  31   an  provided at each of the plurality of link members  21   a  constituting the insertion portion driving mechanism  20  of the bending portion  14  is electrically connected to the command control section  5 A. 
       FIG. 10  is a block diagram showing a specific configuration of the command control section  5 A and the actuator control block  31  shown in  FIG. 9 . 
     As shown in  FIG. 10 , the command control section  5 A includes: an inputting section I/F  33  for inputting an operation command value signal from the operation command section  7 ; inputting sections I/F  34  and I/F  35  for inputting a setting command value from the setting value command section  8 ; and a central processing unit (e.g., a CPU)  32  that controls driving sections  10   b  in the first, second, . . . , nth actuator control blocks  31   a   1  to  31   an  based on various command value signals inputted via the I/Fs  33  to  35 . 
     In the case where the joystick  7   a  outputs analog operation command value signals, the inputting section I/F  33  is capable of inputting such an analog signal. In addition, in the case where the joystick  7   a  outputs other digital operation command value signals, the inputting section I/F  33  is capable of inputting such a digital signal. 
     An analog setting value command signal required to consecutively move a plurality of link members  21   a  can also be inputted through the inputting section I/F  34 , while digital setting command values for changing parameters and the like can be inputted through the inputting section I/F  35 . The inputting section I/F  34  and the inputting section I/F  35  may also be configured as one I/F. 
     On the other hand, the actuator control block  31  performs various computational processing at high speed, and includes: a digital signal processor (hereinafter referred to as a DSP)  36  that creates and outputs a driving command value signal based on computation results; a control command value outputting section  37  that creates and outputs an operation output value signal based on a driving command value signal (servo command value signal) from the DSP  36 ; a motor  27  that is the driving section  10   b  whose rotation is controlled based on the operation output value signal (driving signal) from the control command value outputting section  37 ; a sensor  38  that is first detecting section such as an encoder that detects rotational positions of the motor  27 , a potentiometer  23  that detects rotational angles of the link member  21   a , or the like; and a signal inputting section  39  that detects a state quantity detection signal that is position information detected by the sensor  38  and outputs the state quantity detection signal to the DSP  36 . 
     While the motor  27  is used in the present embodiment as the driving section  10   b , the present invention is not limited to this arrangement. Instead, configurations are possible in which another actuator is used as the driving section  10   b.    
       FIG. 11  is a block diagram showing a specific configuration of the actuator control block, while  FIG. 12  is a block diagram of the servo controller shown in  FIG. 11 . 
     In the actuator control block  31  shown in  FIG. 10 , the DSP  36  constitutes the servo controller  36 A shown in  FIG. 11 . The servo controller  36 A creates an operation output value signal (driving signal) based on a supplied servo command value signal, and outputs the same to a driver (amplifier)  37   a  that is the control command value outputting section  37 . The servo controller  36 A may be replaced with the CPU  32  shown in  FIG. 10 . 
     The driver  37   a  amplifies the supplied operation output value signal to rotate the motor  27 . Consequently, due to the rotation of the motor  27 , the link member  21   a  shown in  FIG. 5  rotationally moves. At this point, the sensor  38  creates a state quantity detection signal of the link member  21   a  and outputs the same to a detecting section (amplifier)  39   a  that is the signal inputting section  39 . 
     The detecting section  39   a  amplifies the supplied state quantity detection signal and outputs the same to the servo controller  36 A. Accordingly, the servo controller  36 A is arranged to perform rotational control of the motor  27  while comparing the supplied state quantity detection signal and servo command value signal. 
     In this case, as shown in  FIG. 12 , the servo controller  36 A creates an operation output value signal (driving signal) based on a supplied servo command value signal and a state detection signal that is displacement information of the motor  27  obtained from the sensor  38  by performing PD control such as known proportional/differential control using a PD control section  40 , and rotationally controls the motor  27  by supplying the operation output value signal thereto. 
     With the endoscope  2  provided with the bending portion  14  having such a multi-joint link structure, in order to perform insertion in a shape conforming to the interior shape of a tube cavity such as the large intestine, it is required that the distal end-side link member  21   a   1  be controlled to an optimum attitude angle and, at the same time, the plurality of other link members  21   a  contiguous to the distal end-side link member  21   a   1  be controlled in conjunction thereto. A basic control method used in the above-described present invention will now be described with reference to  FIGS. 13 to 15 . 
       FIGS. 13 to 15  are for describing attitude control of a bending portion having a multi-joint link structure and are explanatory diagrams corresponding to link members  21   a   1  to  21   a   3  on the distal end portion  13  side, wherein:  FIG. 13  is a diagram showing a state in which the distal end portion  13  side link member  21   a   1  assumes a predetermined distal end position and an attitude vector;  FIG. 14  is a diagram showing states of other link members which are anticipated when the link member  21   a   1  shown in  FIG. 13  is in the attitude state shown therein; and  FIG. 15  is a diagram showing a state of a predetermined position and attitude vector when attitude control is independently performed on only the distal end portion  13  side link member  21   a   1 . 
     The command control section  5 A of the controller  5  according to the present embodiment is arranged so that, when respectively performing attitude control on each of the plurality of link members  21   a   1  to  21   an  that constitute the bending portion  14 , computational processing based on kinematics (forward kinematics and inverse kinematics), to be described later, is performed. 
     Computational processing based on forward kinematics refers to computational processing for determining a position/attitude vector of a distal end portion when an angle of each joint (each link member  21   a ) is known, while computational processing based on inverse kinematics refers to computational processing for determining an angle of each joint (each link member  21   a ) when a position/attitude vector of a distal end portion is known. 
     The command control section  5 A performs computational processing based on a basic formula that quantifies robot kinematics, to be described later. Such a basic formula that quantifies robot kinematics is provided below. Hereinafter, for simplicity, descriptions will only be given on movement involving three links and limited, as described above, to a two-dimensional plane. However, replacement of two-dimensional planar movement by a three-dimensional planar movement can be accommodated by similarly replacing known robotic coordinate conversion processing with processing by the DH convention (Denavit-Hartenberg convention). 
     Now, if x denotes end-point coordinates, q denotes joint coordinates and J denotes a Jacobian (velocity vector), the following formula can be defined. It is assumed that x, q and J denote respective vectors.
 
Position relationship between end-point and joint  x=p ( q )  (Formula 1)
 
       FIG. 13  represents two-dimensional coordinates and therefore may be expressed as 
             x   =       (         X           Y         )     .           Velocity relationship between end-point and joint ( dx/dt )= J ·( dq/dt )  (Formula 2)
 
     By solving the above formulas (Formula 1, Formula 2) and the kinematics (Lagrangian) of each link restraint condition, the following robot dynamics (the relationship between torque τ(or δ 2 q/δt 2 ) and dynamics at the joint coordinates) can be derived.
 
τ= H ( q )·( d   2   q/dt   2 )+ h ( q ,( dq/dt ))+ g ( q )−τ EXT ,  (Formula 3)
 
where H(q) represents an inertial matrix term, h represents a dynamics term dependent on Coriolis and attitude variations, g represents a gravitational force term and τEXT represents a disturbance element.
 
     With respect to each joint (that is each of the link members  21   a  denoted by q 1 , q 2  and q 3  in  FIG. 13 ) and the end-point position (the position of the distal end-side link member  21   a   1  and denoted by q 1 ), as for the dynamic relationship between end-point position acceleration and joint acceleration, 
     matrix space can be decomposed into a kernel space (kernel) and a null space (null) using the relationships expressed by Formulas 1 to 3 above and the result of a temporal differentiation operation performed on both sides of Formula 2 by performing matrix decomposition (singular value decomposition or the like) of a relationship expressed as X=J·(d 2 q/dt 2 )+(dJ/dt)·(dq/dt) and the right-hand side. 
     Consequently, Formula 4 presented below can be derived.
 
( d   2   q/dt   2 )= J   # (( d   2   x/dt   2 )−( dJ/dt )·( dq/dt ))+( I−J   #   ×J )·( d   2   q/dt   2 )  (Formula 4)
 
     Note that the notation # in Formula 4 represents a pseudo-inverse matrix. Generally speaking, in Formula 4, the first term of the left-hand side represents movement of the end-point position and the second term thereof represents movement of the respective joints other than the end-point. Therefore, in the case where the end-point position (the position of the distal end-side link member  21   a   1  and denoted by q 1 ) is determined, attitudes of subsequent joints (other link members  21   a   2  to  21   an  and denoted by q 1 , q 2 ) are not uniquely determined. 
     In other words, as shown in  FIG. 14 , when the position of the distal end portion q 1  is determined, attitudes that can be assumed by a link member including q 1  and constituted by q 2  and q 3  may include attitudes depicted by the dotted line in the diagram in addition to those depicted by the solid line, suggesting that the attitude is not uniquely determined. Therefore, each of the link members  21   a  of the bending portion  14  will acquire redundancy of a robot attitude. 
     While the command control section  5 A of the controller  5  performs a calculation of a torque to be assigned to each link in order to control the link motion equations expressed as Formulas 3 and 4 provided above or, in other words, performs the calculations expressed as Formulas 7 and 8 to be described later, as shown in  FIG. 15 , the command control section  5 A is arranged so as to perform computational processing based on link position/attitude kinematics for the link members  21   a   2  and  21   a   3  (q 2  and q 3 ) in the stage subsequent to the distal end portion and to perform computational processing based on an algorithm (stored in a memory, not shown) that performs independent driving control for the distal end-side link member  21   a   1  (q 1 ). 
     Consequently, when the position and attitude (direction) of the distal end-side link member  21   a   1  is determined, it is possible to calculate angles of other link members  21  contiguous to the distal end-side link member  21   a   1  by performing the computational processing described above. 
     Next, a specific configuration of the servo controller  36 A for performing computational processing based on the kinematics (forward kinematics and inverse kinematics) and a control method thereof will be described with reference to  FIGS. 16 to 21 . 
       FIGS. 16 to 21  are for describing a specific configuration of the servo controller  36 A and a control method thereof, wherein:  FIG. 16  is a block diagram showing a schematic configuration of the servo controller  36 A;  FIG. 17  is a block diagram showing a specific configuration of the control law computing section  36 B shown in  FIG. 16 ;  FIG. 18  is a block diagram showing a schematic configuration of the dynamics computing section  43  shown in  FIG. 17 ;  FIG. 19  is a block diagram showing a specific configuration of the dynamics computing section  43  shown in  FIG. 18 ;  FIG. 20  is a block diagram showing a schematic configuration of the kinematics computing section  41  shown in  FIG. 17 ; and  FIG. 21  is a block diagram showing a specific configuration of the kinematics computing section  41  shown in  FIG. 20 . 
     As shown in  FIG. 16 , the servo controller  36 A includes a control law computing section  36 B to which is supplied: command value information (also including setting value information) such as setting command value signals including a servo command value signal at the distal end-side link member  21   a   1  or each link member  21   a ; and position feedback information (hereinafter referred to as position F/B information) such as a state quantity detection signal at each link member  21   a.    
     Based on the supplied command value information and position F/B information, the control law computing section  36 B performs computational processing for obtaining joint torque command value signals as driving command value signals corresponding to each link member  21   a  at the kinematics computing section  41  and the dynamics computing section  43 , to be described later, and outputs the same to the driving section  10   b.    
     A specific configuration of the control law computing section  36 B is shown in  FIG. 17 . 
     As shown in  FIG. 17 , the control law computing section  36 B includes: the kinematics computing section  41  to which command value position information that is distal end position coordinates of the distal end-side link member  21   a   1  and joint position F/B information of each joint (each link member  21   a ) are inputted, and which uses the information to perform computational processing based on kinematics; the dynamics computing section  43  to which a computation result of the kinematics computing section  41 , the command value information and the joint position F/B information are inputted, and which uses the information to perform dynamics computational processing to derive a dynamic part of a variation of each link member  21   a ; and the control computing section  42  to which the command value information and respective computation results of the kinematics computing section  41  and the dynamics computing section  43  are inputted, and which, based on the information, performs computational processing of a joint torque command value signal required to control each link member  21   a.    
     The control law computing section  36 B controls the insertion portion driving mechanism (manipulator)  20  by supplying the created joint torque command value signal to the driving section  10   b  in the actuator control block  31 . 
     At this point, the manipulator  20  outputs joint position F/B information of each joint that is a state quantity detection signal detected by the sensor  38  in the actuator control block  31  to the kinematics computing section  41  and the dynamics computing section  43 . 
       FIG. 18  shows a schematic configuration of the dynamics computing section  43 , and  FIG. 19  shows a specific configuration of the dynamics computing section. 
     As shown in  FIG. 18 , a Jacobian (a velocity vector that is also referred to as J or Jacobian J), to be described later, which is a computation result of the kinematics computing section  41 , the command value information and the joint position F/B information are inputted to the dynamics computing section  43 , whereby the dynamics computing section  43  performs dynamics computational processing using the information in order to derive a dynamic part of a variation of each link member  21   a  or, more specifically, a position deviation, a Jacobian JS, joint position velocity/acceleration of each link member  21   a , and outputs the same as computational processing results. 
     More specifically, as shown in  FIG. 19 , the dynamics computing section  43  includes a forward kinematics computing section  44 , a temporal differentiation computing section  45  and a temporal differentiation computing section  46 . 
     The forward kinematics computing section  44  performs computational processing based on above-described forward kinematics using the joint position F/B information. A computation result thereof is subtracted from distal end position information of the distal end-side link member  21   a   1  by a subtracter to derive a position deviation e of each link member  21   a.    
     The joint position F/B information and the Jacobian J are inputted to the temporal differentiation computing section  45 . By performing temporal differentiation computational processing using the joint position F/B information and the Jacobian J, the temporal differentiation computing section  45  creates a displacement of each link member  21   a  or, more specifically, a Jacobian velocity δJ/δt and a joint position velocity δq/δt. 
     The temporal differentiation computing section  46  receives the joint position velocity δq/δt as an input, and by performing temporal differentiation computational processing, creates a joint position acceleration δ 2 q/δt 2 . 
       FIG. 20  shows a schematic configuration of the kinematics computing section  41 , and  FIG. 21  shows a specific configuration of the kinematics computing section  41 . 
     As shown in  FIG. 20 , the command value information and the joint position F/B information are inputted to the kinematics computing section  41 . By performing computational processing based on kinematics using the information, the kinematics computing section  41  derives a Jacobian J of the distal end-side link member  21   a   1 , a pseudo-inverse matrix J +  of the Jacobian J and a null-space pseudo-inverse matrix (I−J + J) of the Jacobian J, and outputs the same as computational processing results. 
     More specifically, as shown in  FIG. 21 , the kinematics computing section  41  includes a Jacobian computing section  47 , a pseudo-inverse matrix computing section  48 , and a Jacobian null-space computing section  49 . 
     The Jacobian computing section  47  performs computational processing for obtaining a Jacobian J based the command position information and the position F/B information, and outputs the obtained Jacobian J to the control computing section  42  shown in  FIG. 17 , the pseudo-inverse matrix computing section  48  and the Jacobian null-space computing section  49 . 
     Formula 5 that is based on Jacobian computational processing by the Jacobian computing section  47  is presented below. 
     
       
         
           
             
               
                 
                   J 
                   = 
                   
                     ( 
                     
                       
                         
                           
                             
                               ∂ 
                               
                                 X 
                                 1 
                               
                             
                             
                               ∂ 
                               
                                 q 
                                 1 
                               
                             
                           
                         
                         
                           
                             
                               ∂ 
                               
                                 X 
                                 1 
                               
                             
                             
                               ∂ 
                               
                                 q 
                                 2 
                               
                             
                           
                         
                         
                           ⋯ 
                         
                         
                           
                             
                               ∂ 
                               
                                 X 
                                 1 
                               
                             
                             
                               ∂ 
                               
                                 q 
                                 n 
                               
                             
                           
                         
                       
                       
                         
                           ⋮ 
                         
                         
                           ⋮ 
                         
                         
                           ⋮ 
                         
                         
                           ⋮ 
                         
                       
                       
                         
                           
                             
                               ∂ 
                               
                                 X 
                                 n 
                               
                             
                             
                               ∂ 
                               
                                 q 
                                 1 
                               
                             
                           
                         
                         
                           
                             
                               ∂ 
                               
                                 X 
                                 n 
                               
                             
                             
                               ∂ 
                               
                                 q 
                                 2 
                               
                             
                           
                         
                         
                           ⋯ 
                         
                         
                           
                             
                               ∂ 
                               
                                 X 
                                 n 
                               
                             
                             
                               ∂ 
                               
                                 q 
                                 n 
                               
                             
                           
                         
                       
                     
                     ) 
                   
                 
               
               
                 
                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     5 
                   
                   ) 
                 
               
             
           
         
       
     
     The pseudo-inverse matrix computing section  48  receives the Jacobian J as input, and by performing generalized inverse matrix computational processing thereon, creates a pseudo-inverse matrix J +  and outputs the same to the control computing section  42  shown in  FIG. 17  and the Jacobian null-space computing section  49 . 
     Formula 6 that is based on generalized inverse matrix computational processing is provided below.
 
 J   + =( J   T   ·J ) −1   ·J   T   (Formula 6)
 
     Note that the superscript T in the formula represents a transposed matrix. 
     By performing Jacobian null-space computational processing on the supplied Jacobian J and pseudo-inverse matrix J + , the Jacobian null-space computing section  49  creates a pseudo-inverse matrix I−J + J and outputs the same to the control computing section  42  shown in  FIG. 17 . 
     Consequently, the Jacobian J, the pseudo-inverse matrix J +  of the Jacobian J and the Jacobian null-space pseudo-inverse matrix (I−J + J) are to be supplied to the control computing section  42  shown in  FIG. 17  as computational processing results of the kinematics computing section  41 . The control computing section  42  performs PD control based on the above-described command values and state quantity. 
     Next, control law formulas necessary for various computational processing performed at the above-mentioned control law computing section  36 B shown in  FIG. 17  will be described. 
     The endoscope apparatus  1  that uses a medical control apparatus according to the present invention comprises the insertion portion driving mechanism  20  that includes a plurality of link members  21   a  and a plurality of joint members  21   b  and which constitutes a manipulator. Therefore, the control law computing section  36 B shown in  FIG. 17  derives the joint torque command value signal by performing various computational processing based on the above-described Formula 3 and Formula 4 that are manipulator dynamic equations and further using various formulas based on a manipulator control law, to be described later. 
     A formula based on the manipulator control law is presented below. In this case, if τ represents joint torque and e represents position deviation, 
                   τ   =       ⁢         J   #     ·     (           ∂   2     ⁢   x       ∂     t   2         +       K   D     ·       ∂   e       ∂   t         +       K   P     ·   e     -         ∂   J       ∂   t       ·       ∂   q       ∂   t           )       +       (     I   -       J   #     ·   J       )     ·         ∂   2     ⁢   q       ∂     t   2         ·   ϕ     +     h   ⁢     (     q   ,       ∂   q       ∂   t         )       +     g   ⁡     (   q   )                 (     Formula   ⁢           ⁢   7     )               
is derived,
 
where, KP represents control quantity proportional gain, KD represents control quantity differential gain, e represents a position deviation calculated from a command value and a state quantity, φ represents a control parameter for weighting the above-mentioned redundancy, and h(*,*), g are the parameters described earlier.
 
                   ϕ   =     -     (         K   NULL     ·       ∂   q       ∂   t         +         ∂     (     I   -       J   #     ·   J       )         ∂   t       ·       ∂   q       ∂   t           )               (     Formula   ⁢           ⁢   8     )               
is derived, where K NULL  represents a coefficient to be used by the control computing section  42 .
 
     With Formula 7, a joint torque τ can be determined by applying various computational processing results obtained by the kinematics computing section  41 , the dynamics computing section  43  and the control computing section  42  shown in  FIG. 17 . 
     With Formula 8, values other than K NULL  are computational results obtained by the kinematics computing section  41 . 
     Meanwhile, when inserting the insertion portion  9  of the endoscope  2  configured as described above into a body cavity, in order to prevent the bending portion  14  from becoming a rigid body, the entire bending portion is desirably provided with flexible dynamic characteristics. To this end, the insertion portion driving mechanism  20  achieves such dynamic characteristics by providing the distal end portion thereof with a combination of a spring  20   a  and a damper  20   b  such as those shown in  FIG. 22 . 
     In other words, due to a viscoelastic effect caused by the spring  20   a  and the damper  20   b , when a force F shown in  FIG. 22  is applied to the distal end portion  13  of the insertion portion  9 , the bending portion  14  will acquire flexible characteristics or, in other words, compliance characteristics. 
     A control law implemented by the control computing section  42  will be described below. 
     First, a motion equation of dynamic characteristics shown in  FIG. 22  may be expressed as Formula 9. 
                   F   =       M   ·         ∂   2     ⁢   x       ∂   t   2         +     D   ·       ∂   x       ∂   t         +   Kx             (     Formula   ⁢           ⁢   9     )               
From Formula 9, if a command position of a manipulator end-point is represented by X, a force applied to the end-point by F TIP , and a position occurring as a result thereof by X D , the dynamic characteristics of the distal end having compliance characteristics may be expressed as Formula 10.
 
     
       
         
           
             
               
                 
                   
                     
                       M 
                       · 
                       
                         
                           
                             ∂ 
                             2 
                           
                           ⁢ 
                           X 
                         
                         
                           ∂ 
                           
                             t 
                             2 
                           
                         
                       
                     
                     + 
                     
                       D 
                       · 
                       
                         
                           ∂ 
                           
                             ( 
                             
                               X 
                               - 
                               
                                 X 
                                 D 
                               
                             
                             ) 
                           
                         
                         
                           ∂ 
                           t 
                         
                       
                     
                     + 
                     
                       K 
                       · 
                       
                         ( 
                         
                           X 
                           - 
                           
                             X 
                             D 
                           
                         
                         ) 
                       
                     
                   
                   = 
                   
                     F 
                     TIP 
                   
                 
               
               
                 
                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     10 
                   
                   ) 
                 
               
             
           
         
       
     
     In this case, a joint force τ F  equivalent to and opposing F TIP  may be expressed as Formula 11.
 
τ F   =J   T ( q )· F   (Formula 11)
 
     For simplicity, a motion equation when an external force F is applied from the exterior environment in a state where the distal end portion is immobilized may be expressed with respect solely to a distal end portion mass M as Formula 12. 
     
       
         
           
             
               
                 
                   
                     
                       
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                         ⁡ 
                         
                           ( 
                           q 
                           ) 
                         
                       
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                             2 
                           
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                           q 
                         
                         
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                             2 
                           
                         
                       
                     
                     + 
                     
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                         ) 
                       
                     
                     + 
                     
                       g 
                       ⁡ 
                       
                         ( 
                         q 
                         ) 
                       
                     
                   
                   = 
                   
                     τ 
                     + 
                     
                       
                         
                           J 
                           ⁡ 
                           
                             ( 
                             q 
                             ) 
                           
                         
                         T 
                       
                       · 
                       F 
                     
                   
                 
               
               
                 
                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     12 
                   
                   ) 
                 
               
             
           
         
       
     
     As described above, Formula 14a and Formula 14b may be derived as manipulator motion equations from Formula 13. 
     
       
         
           
             
               
                 
                   
                     
                       
                         
                             
                         
                         ⁢ 
                         
                           
                             
                               ∂ 
                               X 
                             
                             
                               ∂ 
                               t 
                             
                           
                           = 
                           
                             
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                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     13 
                   
                   ) 
                 
               
             
             
               
                 
                   τ 
                   = 
                   
                     
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                       ⁢ 
                       
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                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
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                     14 
                     ⁢ 
                     a 
                   
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                     14 
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                     b 
                   
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     When manipulator dynamics including parameters of each link is once again described, compliance characteristics may be expressed as Formula 15. 
     
       
         
           
             
               
                 
                   
                     
                       
                         M 
                         ⁡ 
                         
                           ( 
                           q 
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                       F 
                     
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                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     15 
                   
                   ) 
                 
               
             
           
         
       
     
     Assigning Formula 15 to Formula 14a results in Formula 16. 
     
       
         
           
             
               
                 
                   τ 
                   = 
                   
                     
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                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     16 
                   
                   ) 
                 
               
             
           
         
       
     
     Formula 16 expresses the same relationship as Formula 7, albeit in a different form. In this case, for simplicity, a controlling expression of a torque command where the distal end portion has spring characteristics K is derived. 
     With Formula 16, since the first and second terms of the right hand-side of Formula 17 presented below can be omitted when velocity is low, Formula 17 is derived. Further assuming that D=0, K F =I, and a distal end displacement ΔX=(X−X D ) is relatively small, ΔX=J(q)·Δq is approximately true. 
     As a result, Formula 18 is derived. Formula 18 indicates what kind of a torque command was created by each joint when K is set as desired compliance characteristics. 
     
       
         
           
             
               
                 
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                   = 
                   
                     
                       
                         - 
                         
                           
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                     17 
                   
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                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     18 
                   
                   ) 
                 
               
             
           
         
       
     
     From the above, with respect to Formula 7 and Formula 16, generally speaking, it may be understood that the first item of the left-hand side of Formula 4 represents a movement of a hand-held position while the second term thereof represents a movement of a joint. 
     Then, the command control section  5 A of the controller  5  performs torque calculations in real-time using Formula 7 and Formula 8, as described above. However, computational processing based on an algorithm for drive controlling the driving section  10   b  may be performed on a value corresponding to the second term of the Formula 7 as a result of computational processing of weighting in accordance with a movable range of the link member  21   a.    
     Accordingly, computational processing is performed by changing the algorithm of the second term of Formula 7 or (I−J # ·J)·(d 2 q/dt 2 ) to, for example a weighting function φ that is a parameter like that shown in  FIG. 24 . In other words, the weighting function φ performs computational processing such that, when determining an angle of each link member  21   a , weighting increases at the limit of the movable range of each link and decreases in the vicinity of a neutral position in the movable range. Therefore, the coefficient is for setting weighting of the attitude of each link to an attitude that is as close to neutral as possible, and for eliminating forced attitudes and limiting movement to a mobile range. 
     For example, a range of ±90 degrees is set in advance as a tolerable range of an angle formed by adjacent link members  21   a . In other words, the parameter is arranged so that the angle formed by adjacent link members  21   a  does not assume an acute angle. 
     Consequently, it is possible to perform attitude control so that each link member  21   a  of the insertion portion driving mechanism  20  is mobile and smooth. 
     For the weighting function φ, weighting functions such as those represented by any of the graphs shown in  FIGS. 25 to 29  to be described later may be used. The ordinates of  FIGS. 25 to 29  indicate K NULL  as expressed in Formula 8, while abscissas thereof indicate a movable range of each link member  21   a  (a detected angle of each link member  21   a ). The positive movable limit value is set to 90 degrees and the negative movable limit value is set to −90 degrees. 
       FIG. 25  is a graph showing characteristics of a first variation of the weighting function φ. As shown in  FIG. 25 , the weighting function φ is a linear function, and is a weighting function obtained by performing computational processing corresponding to position variations of each link member  21   a  as shown below.
 
φ= a ·|( q   i   −q   i     —   org)|,  (Formula 19)
 
where α represents a negative definite value, qi represents each link position, and qi_org represents a link origin position.
 
       FIG. 26  is a graph showing characteristics of a second variation of the weighting function φ. As shown in  FIG. 26 , the weighting function φ is a quadratic function, and is a weighting function obtained by performing computational processing corresponding to position variations of each link member  21   a  as shown below.
 
φ= a ·( q   i   −q   i     —   org) 2 ,  (Formula 20)
 
where, in this case, α represents a negative definite value.
 
       FIG. 27  is a graph showing characteristics of a third variation of the weighting function φ. As shown in  FIG. 27 , the weighting function φ is a weighting function obtained by performing computational processing of partial differentiation corresponding to position variations of each link member  21   a  as shown below. 
                   ϕ   =     a   ⁢       ∑     i   =   1     n     ⁢           ⁢       ∂     W   i       /     ∂     q   i                     (     Formula   ⁢           ⁢   21     )               
where, W i =( q   i   −q   i     —   org)/( q   i max− q   i min) 2  
 
     In this case, α represents a negative definite value, qi represents each link position, qi_org represents a link origin position, qi_max represents a link upper limit angle value, and qi_min represents a link lower limit angle value. 
       FIG. 28  is a graph showing characteristics of a fourth variation of the weighting function φ. As shown in  FIG. 28 , in some cases, conversely to the weighting function shown in  FIG. 27 , the weighting function shown in  FIG. 28  can be realized as a weighting function that approaches as much as possible the vicinity of the movable limit value by adding an offsetting value of φ to Formula 22, to be described below, to newly set φ and assuming α to be a positive definite value. In this case, α represents a positive definite value. 
       FIG. 29  is a graph showing characteristics of a fifth variation of the weighting function φ. As shown in  FIG. 29 , to achieve the same effects as the fourth variation, the weighting function φ may also be arranged to use an absolute value of a trigonometrical function such as that including the dashed line portion shown in the diagram as expressed by Formula 22.
 
 W   i   =a ·tan( q   i   −q   i     —   org),  (Formula 22)
 
where, in this case, α represents a negative definite value.
 
     Consequently, by performing computational processing using the weighing function φ represented by any of the graphs shown in  FIGS. 25 to 29 , it is now possible to eliminate forced attitudes and acquire an angle that enables movement within a mobile range for each link member  21   a.    
     In the present embodiment, instead of performing weighting on each link member  21   a , it is also possible to perform weighting on the entire manipulator  20  to eliminate forced attitudes and enable movement within a mobile range. 
     In such a case, for the weighting function φ, a weighting function that uses a singularity of the manipulator attitude is used. In other words, a manipulability indicator M with respect to the Jacobian J may be defined as shown in Formula 23 below, whereby the manipulability indicator M may be replaced with the weighting function φ. 
     
       
         
           
             
               
                 
                   M 
                   := 
                   
                     
                        
                       
                         J 
                         · 
                         
                           J 
                           T 
                         
                       
                        
                     
                   
                 
               
               
                 
                   ( 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     23 
                   
                   ) 
                 
               
             
           
         
       
     
     Calculating the eigenvalue of J·J T  produces the schema expressed by Formula 24. 
     
       
         
         
             
             
         
       
     
     In other words, as expressed by Formula 23 and Formula 24, a calculation of the eigenvalue of J·J T  normally results in: order of matrix J·J T =Rank (i). However, a case of a singular attitude results in: order of matrix J·J T &lt;Rank (i), thereby decreasing matrix M. Accordingly, by performing computational processing using the manipulability indicator M instead of the weighting function φ, it is possible to perform weighting on the entire manipulator  20  instead of on each link member  21   a  so that forced attitudes can be eliminated and movements can be performed within a mobile range. In this case, the respective link members  21   a  are not uniformly controlled. 
     While weighting functions for several types of attitude control have been shown, in some cases, weighting functions can be combined so that different weighting combinations are selectively performed for each link interval using shaft switching section to be described later. 
     In this case, weighting functions shown in  FIGS. 25 to 29  or weighting functions using a manipulability indicator M such as those expressed by Formula 23 or Formula 24 can be stored for each table. Subsequently, the controller  5  (more specifically, the CPU  32 ) selects a weighting function based on any one of a plurality of tables, and performs computational processing of an angle of each link member  21   a  or each angle of each link member with respect to the entire manipulator. 
     Next, a first embodiment of a controller  5  that performs attitude driving control of the aforementioned bending portion  14  will be described with reference to  FIGS. 30 to 38 . 
       FIGS. 30 to 38  are related to the first embodiment of the present invention.  FIG. 30  is a block diagram showing a specific configuration of the controller  5  of the endoscope apparatus  1 ; and  FIGS. 31 and 32  are diagrams describing attitude control of the insertion portion driving mechanism  20  that constitutes the bending portion  14 , wherein  FIG. 31  shows a state in which a distal end-side link member  21   a   1  is point-locked, and  FIG. 32  shows a state in which point-locking the distal end-side link member  21   a   1  provides a subsequent-stage link member with redundancy. In addition,  FIG. 33  is a block diagram showing a specific configuration of the point lock computing section  50  shown in  FIG. 30 ;  FIG. 34  is a block diagram showing a specific configuration of the inverse kinematics computing section  52  shown in  FIG. 33 ;  FIG. 35  is a diagram explaining attitude control when only the distal end-side link member  21   a   1  is point-locked; and  FIG. 36  is an explanatory diagram explaining attitude control when a fourth link member  21   a   4  is further point-locked. Furthermore,  FIG. 37  is an explanatory diagram explaining attitude control in a case where two locations are point-locked; and  FIG. 38  is a block diagram showing an internal configuration of a controller in which the point lock computing section is provided at each link member  21   a.    
     The controller  5  according to the present embodiment includes the servo controller  36 A that performs attitude control of the bending portion  14  as described earlier. The servo controller  36 A is provided with a point lock computing section  50  having computational processing functions of the control law computing section  36 B. 
     When movement occurs due to the insertion of the bending portion  14 , the servo controller  36  uses the point lock computing section  50  to compute respective angles of the plurality of link members  21   a  so that a position and a direction designated by the operation command section  7  is maintained when a link member  21   a   1  designated by the operation command section  7  as well as other link members  22  contiguous to the link member  21   a   1  pass through the position, and based on the computation results, controls the driving section  10   b  to rotationally move the plurality of link members  21   a.    
     In the present embodiment, the servo controller  36  is also arranged so that when performing computational processing for determining the respective angles of the plurality of link members  21   a  using the point lock computing section  50 , computational processing is performed by manually or automatically selecting any of respective tables storing weighting functions having characteristics such as those shown in  FIGS. 25 to 29  and by using a weighting function based on the table. 
     A configuration of the point lock computing section  50  that performs such computational processing will now be described with reference to  FIGS. 30 ,  33  and  34 . 
     As shown in  FIG. 30 , distal end command value information such as a setting command value signal and the like including a servo command value signal at the distal end-side link member  21   a   1  and position F/B information such as a state quantity detection signal at the distal end-side link member  21   a   1  are supplied to the point lock computing section  50 . 
     Based on the supplied distal end command value information and position F/B information, the point lock computing section  50  performs computational processing at a distal end link root coordinate position calculating section  51  and an inverse kinematics computing section  52 , to be described later, for obtaining a servo position command signal (including a joint torque command value signal) as a driving command value signal corresponding to each link member  21   a.    
     That is, when movement occurs due to the insertion of the bending portion  14 , based on the supplied distal end command value information and position F/B information, the point lock computing section  50  computes respective angles of the plurality of link members  21   a  so that a position and a direction designated by the operation command section  7  is maintained when a link member  21   a   1  designated by the operation command section  7  as well as other link members  22  contiguous to the link member  21   a   1  pass through the position, and outputs the computation results as a servo position command value signal to the driving section  10   b.    
     The distal end command value information and position F/B information used in the computational processing by the point lock computing section  40  represents an angle mutually formed by the plurality of link members  21   a  as well as a variation of the angle that are detected by a sensor  38  that is first detecting section. 
     Accordingly, as a result of the driving section  10   b  respectively controlling the rotational movements of link members  21   a  designated based on the supplied servo position command value signal, the bending portion  14  having the insertion portion driving mechanism  20  will be bent in a shape conforming to the shape of a tube cavity to which the bending portion  14  is inserted. 
       FIG. 31  shows a state in which only the distal end-side link member  21   a   1  is point-locked at an instructed predetermined attitude state. 
     When performing control to such an attitude state, if the joint member  21   b   1  of the distal end portion-side link member  21   a   1  is assumed to be point lock R 1  as shown in  FIG. 32 , the point lock computing section  50  performs computational processing of point lock coordinates of the point lock R 1  to create a servo position command signal necessary for performing attitude control of the two-dimensional position and direction of the distal end-side link member  21   a   1 . 
     In addition, as shown in  FIG. 32 , with an attitude state in which the distal end-side link member  21   a   1  is point-locked, a link portion  20 B constituted by a plurality of link members  21   a   2 ,  21   a   3  and  21   a   4  subsequent to the point lock R 1  acquires redundancy through the above-described attitude control, and can now change to unregulated, arbitrary attitudes as represented by the dashed lines in the diagram. 
     A specific configuration of the point lock computing section  50  is shown in  FIG. 33 . As shown in  FIG. 33 , the point lock computing section  50  includes the distal end link root coordinate position calculating section  51  and the inverse kinematics computing section  52 . 
     Joint angle information of a link member  21   a , distal end command value information that is position information of the distal end-side link member  21   a   1 , and position F/B information are inputted to the distal end link root coordinate position calculating section  51 . Based on the information, the distal end link root coordinate position calculating section  51  calculates a distal end link root coordinate position of the distal end-side link member  21   a   1 , and outputs the calculation result to the inverse kinematics computing section  52 . 
     Distal end command value information and position F/B information from the distal end link root coordinate position calculating section  51  are inputted to the inverse kinematics computing section  52 . Based on the information, the inverse kinematics computing section  52  performs computational processing of root coordinate positions of link members  21   a  subsequent to the distal end-side link member  21   a   1 , and creates and outputs servo position command value signals for link members other than the distal end-side link member  21   a   1 . 
     A specific configuration of the inverse kinematics computing section  52  is shown in  FIG. 34 . As shown in  FIG. 34 , the inverse kinematics computing section  52  includes: a mechanism parameter computing section  53 ; a forward kinematics computing section  54 ; a Jacobian computing section  55 ; a gain  56 ; a matrix computing section  57 ; and an integrating circuit  58 . The mechanism parameter computing section  53  performs computational processing based on the position F/B information to create a distal end link offsetting value for adjusting and controlling the distal end-side link member  21   a   1  to a subtle attitude. A difference between the distal end link offsetting value and the distal end command value information is obtained, and a difference is once again obtained between the difference value and the command value F/B information computationally processed by the forward kinematics computing section  54 . Accordingly, the difference value is supplied to the gain  56  as second-stage position command information. The gain  56  amplifies the supplied second-stage position command information and outputs the same to the matrix computing section  57 . 
     Meanwhile, in the same manner as described with respect to  FIG. 21 , the Jacobian computing section  55  creates a Jacobian J by performing computational processing based on command value information, and outputs the same to the matrix computing section  57 . 
     Based on the supplied second stage position command information, the matrix computing section  57  performs matrix computation processing for determining an attitude (angle) of a link member  21   a  of the second stage and thereafter corresponding to the attitude state of the link member  21   a , and after performing integration processing on the obtained computation result at the integrating circuit  58 , outputs the same as a servo command value signal for the second and subsequent stages to the driving section  10   b.    
     The output of the integrating circuit  58  or, in other words, the servo command value signal for the second and subsequent stages is fed back to a deviation value of the distal end command value information and position F/B information via the Jacobian computing section  55  and the forward kinematics computing section  54 . This is performed in consideration of minimizing occurrences of singular solutions when solving inverse kinematics. 
     Normally, solutions are analytically obtained in inverse kinematics. However, there are cases where an occurrence of a singular solution prevents a solution from being found. For this reason, instead of using inverse kinematics, a method is employed in which inverse kinematics are obtained through forward kinematics, and a structure is provided where a convergence rate is set according to a value of the gain  56 . 
     Accordingly, a link member  21   a  of the second and subsequent stages will be controlled so as to assume subtle attitudes in conjunction with attitude control of the distal end-side link member  21   a   1 . 
       FIG. 35  shows a bending state of the bending portion  14  on which attitude control is performed by the point lock computing section  50  according to the first embodiment. 
     For example, when the operator inputs an instruction to point-lock only the distal end-side link member  21   a   1  using the operation command section  7 , by performing computational processing as described above, the point lock computing section  50  creates a servo position command value signal to point-lock the distal end-side link member  21   a   1  at the point lock coordinates (two-dimensional position and direction) of the point lock R 1 , and provides the servo position command value signal to the driving section  10   b  to control the same. 
     Consequently, the distal end-side link member  21   a   1  of the bending portion  14  is point-locked at the instructed attitude vector (two-dimensional position and direction) at point lock R 1 , as shown in  FIG. 35 . 
     At this point, as was described with reference to the block diagrams shown in  FIGS. 33 and 34 , since the link portion  20 B constituted by the plurality of link members  21   a   2 ,  21   a   3  and  21   a   4  subsequent to the point lock R 1  is subjected to attitude control having redundancy in conjunction with attitude control of the distal end-side link member  21   a   1  by the point lock computing section  50 , an attitude thereof becomes arbitrary with respect to, for example, the direction of the arrow A shown in the diagrams. 
     That is, when movement occurs due to the insertion of the bending portion  14 , the point lock computing section  50  computes respective angles of the plurality of link members  21   a  so that a position and a direction designated by the operation command section  7  is maintained when a link member  21   a   1  designated by the operation command section  7  as well as other link members  21   a  contiguous to the link member  21   a   1  pass through the position, and based on the computation results, controls the driving section  10   b  so as to rotationally move the plurality of link members  21   a.    
     When computationally processing the respective angles of the plurality of link members  21   a , the point lock computing section  50  performs computational processing using a weighting function based on a weighting function table designated by the setting value command section  8 . Consequently, forced attitudes of the plurality of link members  21   a  or the manipulator  20  can be eliminated, an angle necessary for enabling movement in a mobile range can be acquired for each of the plurality of link members  21   a , and based on the computation results, rotational movement of each link member  21   a  is controlled. 
     With the endoscope apparatus  1  as described above, when inserting the insertion portion  9  into the large intestine, the operator inserts the insertion portion  9  having the bending portion  14  via the anus. Then, when the distal end portion  14  of the insertion portion  9  reaches the sigmoid colon segment, the servo controller  36 A point-locks the distal end-side link member  21   a   1  to a two-dimensional position and direction designated by the operation command section  7 . 
     The operator then further inserts the distal end-side link portion  21   a   1  point-locked to the two-dimensional position and direction along the intestinal wall of the sigmoid colon segment. 
     This causes the distal end-side link member  21   a   1  and other link members  21   a  consecutive thereto to be controlled at angles that enable a position and a direction designated by the operation command section  7  to be maintained when passing the position. In other words, the bending portion  14  is to be inserted while performing bending movements so as to assume shapes conforming to the shape of the sigmoid colon segment. As for the link members  21   a   2  to  21   an  of the second and subsequent stages, attitude control having redundancy will be performed as described above. 
     Consequently, since insertion can now be performed in a shape conforming to the sigmoid colon segment into which insertion was conventionally difficult, it is now possible to pass through the sigmoid colon segment with ease. Therefore, since insertions into deep portions of the large intestine can be readily performed, insertability can be improved. 
     With the present embodiment, it is also possible to point-lock an arbitrary link member  21   a  of the second or subsequent stage instead of point-locking only the distal end-side link member  21   a   1 . 
       FIG. 36  is a diagram showing a bending state of the bending portion  14  in a case where attitude control is performed so that there are two point-locked locations;  FIG. 37  is an explanatory diagram explaining a computing method used by the point lock computing section  50  for designating two point-locked locations; and  FIG. 38  is a block diagram showing a configuration of a controller required for designating and controlling a plurality of point-locked locations. 
     As shown in  FIG. 38 , in a configuration for point-locking the distal end-side link member  21   a   1  and arbitrary link members  21   a  of the second and subsequent stages, a plurality of the point lock computing sections  50  (point lock computing sections  50 A 1  to  50 An) is provided in correspondence to the plurality of link members  21   a , whereby the point lock computing sections  50  are connected so that a servo command value signal for obtaining a subsequent-stage point lock coordinate position is inputtable to the point lock computing section  50  of the subsequent stage. 
     That is, assuming that the block corresponding to the distal end-side link member  21   a   1  is the point lock computing section  50 A 1 , the point lock computing section  50 A 2  corresponding to the subsequent-stage link member  21   a   2  acquires a servo position command value signal that is an output of the point lock computing section  50 A 1  as an input signal for computing a second point lock position. 
     The servo controller  36 A may be configured by, in a similar manner, subsequently providing point lock computing sections  50 A 3  to  50 An in a quantity corresponding to the number of link members  21   a  to be point-locked among the plurality of link members  21   a.    
     In the configuration shown in  FIG. 38 , when two point lock locations are designated, computational processing is respectively performed by the plurality of point lock computing sections  50 A 1 ,  50 A 2 , . . . ,  50 An to  50 AN based on the position command value signal of the distal end-side link member  21   a   1 . 
     In this case, when assuming that, in addition to the point lock R 1 , the second point lock location is the joint member  21   b   3  of the third link member  21   a   3 , the point lock location of the joint member  21   b   3  (q 3 ) is assumed to be a virtual distal end position, as shown in  FIG. 37 . In other words, a link member  21   a  corresponding to q 4  that has q 3  as a virtual distal end position becomes the virtual distal end-side link member  21   a.    
     Then, computational processing is performed by the corresponding point lock computing section  50  so as to perform point-lock at an attitude vector (two-dimensional or three-dimensional position and direction) of q 4  of the link member  21   a , Consequently, it is now possible to perform computational processing necessary for performing point lock at the two locations q 1  and q 4  of the distal end-side link member  21   a   1 . 
     Designation of a link member  21   a  to be point-locked among the plurality of link members  21   a  is to be performed at the operation command section  7 . 
       FIG. 36  shows a bending state of the bending portion  14  in a case where attitude control is performed so that there are two point-locked locations. 
     As shown in  FIG. 36 , for example, when the operator inputs an instruction for point-locking the distal end-side link member  21   a   1  and the fourth-stage link member  21   a   4  at a two-dimensional position and direction using the operation command section  7 , by performing computational processing such as that described above, the point lock computing sections  50 A 1  and  50 A 4  (the point lock computing section corresponding to the fourth-stage link member  21   a   4 , not shown) respectively create a servo position command value signal for point-locking the distal end-side link member  21   a   1  and the fourth-stage link member  21   a   4  at point lock coordinate values of point lock R 1  and point lock R 2 , and provide the signals to the driving section  10   b  to control the same. 
     Consequently, as shown in  FIG. 36 , the distal end-side link member  21   a   1  of the bending portion  14  is point-locked at the instructed attitude vector (two-dimensional position and direction) at point lock R 1 . At the same time, the fourth-stage link member  21   a   4  is point-locked at the instructed attitude vector (two-dimensional position and direction) at point lock R 1 . 
     At this point, as was described with reference to the block diagrams shown in  FIGS. 33 and 34 , since the link portion  20 B constituted by the plurality of link members  21   a   2  and  21   a   3  subsequent to the point lock R 1  and a link member  20 C constituted by the plurality of link members  21   a   5  and  21   a   6  subsequent to the point lock R 2  are subjected to attitude control having redundancy in conjunction with attitude control of the distal end-side link member  21   a   1  by the point lock computing section  50 , an attitude thereof becomes arbitrary with respect to, for example, the direction of an arrow A shown in the diagrams. 
     That is, when movement occurs due to the insertion of the bending portion  14 , the point lock computing sections  50 A 1  and  50 A 2  compute respective angles of the plurality of link members  21   a  so that the position and a direction designated by the operation command section  7  are maintained when link members  21   a   1  and  21   a   4  designated by the operation command section  7  as well as other link members  21   a  respectively contiguous to the link members  21   a   1  and  21   a   4  pass through the position, and based on the computation results, controls the driving section  10   b  so as to rotationally move the plurality of link members  21   a.    
     With the endoscope apparatus  1  as described above, when inserting the insertion portion  9  into the large intestine, the operator inserts the insertion portion  9  having the bending portion  14  via the anus. Then, when the distal end portion  14  of the insertion portion  9  reaches the sigmoid colon segment, the servo controller  36 A point-locks the distal end-side link member  21   a   1  to a two-dimensional position and direction designated by the operation command section  7 . 
     The operator then further inserts the distal end-side link portion  21   a  point-locked to the two-dimensional position and direction along the intestinal wall of the sigmoid colon segment. 
     This causes the distal end-side link member  21   a   1  and other link members  21   a  consecutive thereto to be controlled at angles enabling passage of a position designated by the operation command section  7  while maintaining the position and a direction designated by the operation command section  7 . 
     As insertion of the bending portion  14  proceeds, the servo controller  36 A point-locks the designated link member  21   a   4  to a two-dimensional position and direction obtained by the point lock computing section  50 A 5 . 
     The operator then further inserts the intermediate link portion  21   a   4  point-locked to the two-dimensional position and direction along the intestinal wall of the sigmoid colon segment. 
     This causes the link member  21   a   4  and other link members  21   a  consecutive thereto to be controlled in the same manner as the distal end-side link member  21   a   1  and other link members  21   a  consecutive thereto at angles enabling passage of a position designated by the operation command section  7  while maintaining the position and a direction designated by the operation command section  7 . 
     In other words, the bending portion  14  is to be inserted while performing bending movements into shapes conforming to the shape of the sigmoid colon segment. As for the link members  21   a   2  to  21   an  of the second and subsequent stages, attitude control having redundancy is performed as described above. 
     Consequently, when inserting the insertion portion  9  into the large intestine, since insertion can be performed in a shape more conforming to the sigmoid colon segment than a state in which the distal end-side link member  21   a   1  is point-locked, it is now possible to pass through the sigmoid colon segment with greater ease. Therefore, since insertions into deep portions of the large intestine can be more readily performed, insertability can be improved. 
     For the present embodiment, while point-locking a two-dimensional position and direction of an arbitrary link member  21   a  among the plurality of link members  21   a  has been described, the present invention is not limited to this arrangement. Instead, the present invention may be configured so that a three-dimensional position and direction of an arbitrary link member  21   a  are point-locked. 
     For the present embodiment, although a description has been given on point-locking an arbitrary link member  21   a  while performing attitude control of other link members  21   a  that allows changing into arbitrary redundant attitudes using the servo controller  36 A having the point lock computing section  50 , when withdrawing the insertion portion  9  from the inside of a tube cavity such as the large intestine into which the insertion portion  9  has been inserted, control may be performed so that, for example, attitude control of the entire bending portion  14  or a part of the link members  21   a  is released by suspending driving of the driving section  10   b  so that an unloaded free state (a state that enables free rotational movement) is attained. Consequently, the insertion portion  9  can be readily withdrawn from inside the tube cavity. 
     In addition, as shown in  FIG. 39 , the present invention may be configured by providing driving shaft selecting section  260  and driving shaft recognizing section  61  so that a link member  21   a  for which attitude control is released to change to a free state is designated based on an operation by the operator. 
     In this case, as shown in  FIG. 39 , the driving shaft selecting section  260  is used by the operator to select a link member  21   a  to be changed to a free state, and the selected operation signal is supplied to the driving shaft recognizing section  61 . Based on the operation signal, the driving shaft recognizing section  61  recognizes position information based on the selected link member  21   a , and outputs a control signal declaring the intent to release attitude control of the recognized link member  21   a  to the control law computing section  36 B (refer to  FIG. 16 ). 
     Then, in the same manner as described above, the control law computing section  36 B performs attitude control of the link member  21   a , and at the same time, controls the driving section  10   b  so that attitude control is released for link members  21   a  based on the control signal. Consequently, the degree of freedom of the bending attitude of the bending portion  14  increases, and the manipulability of the insertion portion  9  can be farther enhanced. 
     As described above, according to the present embodiment, since an arbitrary link member  21   a  including the distal end-side link member among a plurality of link members  21   a  constituting the bending portion  14  of the insertion portion  9  can be point-locked, and attitude control can be performed over the other link members so that arbitrary attitudes having redundancy can be taken, it is now possible to insert the bending portion  14  of the insertion portion  9  in a shape conforming to the interior shape of a tube cavity. As a result, advantageous effects such as improvement of insertability of the insertion portion can be achieved. 
     In the present embodiment, there may be cases where, when the insertion portion  9  is inserted into a tube cavity and attitude control is performed as described above, it is desirable to subtly change the attitude of the point-locked distal end-side link member  21   a   1  or an arbitrary link member  21   a  other than the link member  21   a   1  without changing the attitude state. 
     Since matrix computation of attitudes having redundancy is being performed, a case may occur in which even a subtle movement may cause a significant change in the attitude. Therefore, this is effective when it is desirable to subtly adjust a desired link while maintaining the attitude. 
     In order to satisfy such a demand, for example, as shown in  FIG. 40 , the present embodiment is provided with an offset command inputting section  62  that changes the position or direction of the point-locked distal end-side link member  21   a   1  or an arbitrary link member  21   a  other than the link member  21   a   1  by only a preset quantity. In other words, by using the offset command inputting section  6 , it is now possible to adjust the point-locked distal end-side link member  21   a   1  or an arbitrary link member  21   a  other than the link member  21   a   1  by subtly changing (offsetting) the position or the direction thereof. 
     The offset command inputting section  62  is provided in the servo controller  36 A, and creates and outputs offset command value information indicating whether an arbitrary link member  21   a  is to be offset by a preset quantity. In some cases, the setting quantity of the offset command inputting section  62  may be arranged to be variable. 
     As shown in  FIG. 40 , the offset command value information is added to a servo command value signal, and then subjected to PD control such as proportional/differential control by the PD control section  40  as was described with reference to  FIG. 12  to become an operation command value signal (driving signal) to be provided to the motor  27 . Consequently, since the motor  27  is rotationally controlled based on an operation output-side signal to which an offset quantity has been added, the attitude (position or direction) of the designated link member  21   a  will be subtly offset. 
     As a result, in the case where insertion is impeded due to the point-locked distal end-side link member  21   a   1  or an arbitrary link member  21   a  other than the link member  21   a   1  coming into contact with the intestinal wall of the sigmoid colon segment, the position or the direction of the link member  21   a  is offset. Therefore, insertion can be performed smoothly without inflicting pain on a patient. 
     In the present embodiment, the servo controller  36 A may also be configured by combining the driving shaft selecting section  260  and the driving shaft recognizing section  61  shown in  FIG. 39  with the offset command inputting section  62  shown in  FIG. 40 . Such a configuration is shown in  FIG. 41 . 
     More specifically, as shown in  FIG. 41 , the command control section  5 A having the servo controller  36 A is arranged so that offset command value information from the offset command inputting section  62  is inputted to the inputting I/F  34  while a control signal such as shaft setting information from the driving shaft recognizing section  61  is inputted to the inputting I/F  35 . Based on the information, the CPU  32  is to perform computational processing for controlling the attitude of each link member of the bending portion  14 . Other configurations and advantageous effects are the same as those of the configuration shown in  FIG. 10 . 
     For the present embodiment, while the bending portion  14  having the insertion portion driving mechanism  20  constituting a manipulator has been described as being provided at the insertion portion  9  of the endoscope  2 , the bending portion  14  may be arranged to be provided at an insertion portion of an endoscope insertion aiding device that aids the insertion of the insertion portion  9  into a tube cavity by allowing insertion of the insertion portion  9  of the endoscope  2 . 
     Next, a second embodiment of the present invention will be described with reference to  FIGS. 42 to 49 .  FIG. 42  is a schematic configuration diagram showing a configuration of an insertion portion driving mechanism in which a load detecting section for detecting a load created by coming into contact with an intestinal wall is provided at each link member;  FIG. 43  is a block diagram showing a dynamics computing section included in the load detecting section shown in  FIG. 42  and the control law computing section  36 B;  FIG. 44  is a graph showing characteristics of a detection result from the load detecting section and a coefficient that determines a weighting function; and  FIG. 45  is a graph showing an example of characteristics that differs from those shown in  FIG. 44 ,  FIGS. 46 and 47  present a first variation of the second embodiment, wherein:  FIG. 46  is a graph showing characteristics of a detection result from the load detecting section and time; and  FIG. 47  is a block diagram showing a substantial block configuration for implementing the first variation of the second embodiment.  FIGS. 48 and 49  present a second variation of the second embodiment, wherein:  FIG. 48  is a graph showing characteristics of a detection result from a displacement sensor used as a load detecting section and time; and  FIG. 49  is a block diagram showing a substantial block configuration for implementing the second variation of the second embodiment. 
     The second embodiment describes specific processing for automatically determining a weighting function that is an optimum parameter based on a detection result of a load detecting section  60 , to be described later, in the case where, when inserting the bending portion  14  into a tube cavity, computational processing is performed using a weighting function on angles of a plurality of link members  21  constituting the bending portion  14  or on an angle of an arbitrary link member  21  among the plurality of link members  21 . Otherwise, descriptions on points similar to the first embodiment described above will be omitted. 
     As shown in  FIG. 42 , the load detecting section  60  is respectively provided as load detecting means (second detecting section) at each link member  21   a  constituting the bending portion  14  of the insertion portion  9 . 
     The load detecting section  60  is constituted using, for example, a tension sensor such as a strain gauge, and is respectively provided in a covering tube (not shown) covering each link member  21   a  so as to be disposed at preset locations (for example, four locations when provided every 90 degrees) on the circumferential surface of each link member  21   a.    
     As shown in  FIGS. 42 and 43 , when the bending portion  14  is being inserted into a tube cavity, the load detecting section  60  detects a force (also referred to as tension) created from coming into contact with the intestinal wall or the like, and outputs the detection result as force F/B information to the dynamics computing section  43 A. 
     The dynamics computing section  43 A is provided with a weighting switching computing section  62  as setting section that, based on the detection result from the load detecting section  60 , creates a parameter value necessary for performing computational processing for determining a weighting function and performs computational processing of a weighting function in accordance with the parameter value. 
     The weighting switching computing section  62  has weighting function tables  62   a  respectively storing, for example, the weighting functions shown in  FIGS. 25 to 29  or weighting functions using a manipulability indicator M such as those expressed by Formula 23 or Formula 24. The weighting function table  62   a  can also be arranged to be provided in the command control section  5 A or the like instead of in the weighting switching computing section  62 . 
     The dynamics computing section  43 A causes the weighting switching computing section  62  to perform computational processing on angles of the plurality of link members  21   a  using a weighting function based on position F/B information that is an angular displacement of each link member  21   a , and outputs a weighted servo command value signal to the driving section  10   b.    
     In this case, the weighting switching computing section  62  creates a parameter value necessary for performing computational processing for determining a weighting function based on a detection result from the load detecting section  60 . 
     The weighting switching computing section  62  performs computational processing using a weighting function of any of the weighting function tables  62   a  preset by the operation command section  7  and the created parameter value. 
     In other words, as expressed by Formula 25 below, 
                   ϕ   =     {         -       K   NULL     ⁡     (   F   )         ·     (       ∂   q       ∂   t       )       +       (       ∂     (     I   -       J   #     ·   J       )         ∂   t       )     ⁢     (       ∂   q       ∂   t       )         }             (     Formula   ⁢           ⁢   25     )               
the weighting switching computing section  62  determines K NULL  that is a parameter value from a change in (F) that is a detection result from the load detecting section  60  expressed in Formula 25.
 
     An example of characteristics of the parameter value is depicted in the graph shown in  FIG. 44 . 
     As shown in  FIG. 44 , K NULL  that is the parameter value increases until the value of the force F/B information reaches a presetting value, and consistently takes a constant value after the setting value. In other words, K NULL  gain changes linearly in accordance with the force F/B information, and becomes a parameter value that saturates at a preset arbitrary threshold. The setting value of the threshold of the parameter value K NULL  can also be inputted via the setting value command section  8 . 
     As seen, in the vicinity of the bending portion  14 , a weighting function value φ is attained that realizes an attitude not subjected to the action of disturbance with respect to disturbances such as coming into contact with the intestinal wall. 
     While there are cases where, besides the linear weighting function parameter described above, it is desirable to cancel out non-linear components that occur due to sensor characteristics, sensor implementation or the like, or to intentionally arrange attitudes of movement to be non-linear. As an example thereof the weighting function parameter value K NULL  may take the form of non-linear functions expressed by Formula 26 and Formula 27 below. 
     If a gain maximum value of K NULL  that is a parameter value may be represented by K NULLMAX  and the force F/B information by (F),
 
 K   NULL ( F )=tan( F ) (0≦&lt;F≦β)  (Formula 26)
 
 K   NULL ( F )= K   NULLMAX  (β&gt;F)  (Formula 27)
 
are derived, where β&gt;0.
 
     In this case, resulting characteristics of the parameter value are as depicted by the graph shown in  FIG. 45 . 
     Besides the graph characteristics shown in  FIG. 45 , high-dimensional functions such as expressed by Formula 28 and Formula 29 may also be used. Such Formulas 28 and 29 are provided below.
 
 K   NULL ( F )= a·F   3  (0≦&lt;F≦β)  (Formula 28)
 
 K   NULL ( F )= K   NULLMAX  (β&gt;F)  (Formula 29)
 
are derived, where, β, α&gt;0 (arbitrary value).
 
     Therefore, as described above, the weighting switching computing section  62  is capable of obtaining an optimum weighting function through computational processing performed by changing parameter values when weighting an angle of each link member  21   a  and performing computational processing based on force F/B information from the load detecting section  60 . In other words, a servo command value signal weighted in accordance with force F/B information from the load detecting section  60  can be obtained by the dynamics computing section  43 A, thereby eliminating forced attitudes of an arbitrary link member  21   a  or the entire manipulator  20  and enabling movements within a mobile range. 
     As seen, while movements at optimum attitudes are enabled using load information from the load detecting section  60 , depending on the mounting arrangement of the load detecting section  60 , load due to attitude change and disturbance load may be overlapped on each other. In consideration thereof, it is also possible to arrange characteristics of load that occurs due to attitude change to be stored as a parameter and known sensor characteristics in the controller  5 , and acquire information on a detected disturbance by subtracting the part of the known sensor characteristics by the weighting switching computing section  62 . 
     As for the known sensor characteristics, precise dynamics control may be implemented using force information feedback information on the state quantity detection signal by arranging as a load sensor for operating the bending portion  14 . 
     When inserting the insertion portion  9  into a tube cavity, the endoscope apparatus  1  according to the present embodiment is capable of performing insertion in a safer manner even when the bending portion  14  of the insertion portion  9  comes into contact with the intestinal wall or the like inside the tube cavity and the contact state continues. 
     In other words, the present embodiment is arranged so that, when performing computational processing of weighting on angles of the plurality of link members  21   a  based on a detection result of the load detecting section  60 , a weighting function for the entire manipulator  20  which takes time into consideration and also causes a link member  21   a  that is in contact with the intestinal wall or the like to avoid contact is obtained. Such variations are shown in  FIGS. 46 to 49 . 
       FIGS. 46 and 47  describe a first variation of the second embodiment, wherein:  FIG. 46  is a graph showing characteristics of a detection result from the load detecting section and time; and  FIG. 47  is a block diagram showing a configuration of a substantial part including the weighting switching computing section in the dynamics computing section. The ordinate shown in  FIG. 46  represents a tension sensor value (force F/B information) obtained from a tension sensor (strain gauge) that is the load detecting section; the abscissa represents time (t); and axes  1  and  2  respectively indicate first and second link members  21   a.    
     As shown in  FIG. 46 , during insertion of the insertion portion  9  of the endoscope apparatus  1  into a tube cavity, for example, the tension sensor value of the second link member  21   a   2  from the load detecting section  60  decreases as time advances, while the tension sensor value of the first (distal end-side) link member  21   a   1  from the load detecting section  60  increases after reaching a given predetermined point in time. 
     In other words, this indicates that the first link member  21   a   1  came into contact with the intestinal wall of the large intestine or the like at a given predetermined point in time, thereby causing the tension sensor value to increase with time, and, subsequently, continuation of the contact state of the link member  21   a   1  with the intestinal wall has caused a further increase in the tension sensor value. 
     In consideration thereof, the present embodiment is arranged to perform computational processing to determine a weighting function capable of avoiding such a contact state based on the tension sensor value detected at that point even when a contact state of an arbitrary link member  21   a  with the intestinal wall continues. In other words, it is arranged so that, when determining angles of the plurality of link members  21   a , a weighting function that weights the entirety of the plurality of link members  21   a  or, in other words, the entire manipulator  20  is created instead of a weighting function for each of the link members  21   a  as was used in the second embodiment. 
     More specifically, as shown in  FIG. 47 , temporal integration computing sections  61   a   1 ,  61   a   2 , . . . ,  61   an  respectively provided at each of the plurality of link members  21   a  are arranged to be connected to the weighting function switching computing section  62 A in the dynamics computing section  43 . 
     Tension sensor values F 1 , F 2 , . . . , Fn from the load detecting section  60  provided at the respective link members  21   a  are respectively supplied to each of the temporal integration computing sections  61   a   1 ,  61   a   2 , . . . ,  61   an.    
     The temporal integration computing section  61   a   1  performs temporal integration computation processing for obtaining an evaluation function using the supplied tension sensor value F 1 , and an obtained evaluation function SF 1  is outputted to the weighting function switching computing section  62 A. 
     Temporal integration computation processing is performed in the same manner by the temporal integration computing sections  61   a   2 , . . . ,  61   an  to respectively determine evaluation functions SF 2 , . . . , SFn to be respectively outputted to the weighting function switching computing section  62 A. 
     A formula based on computational processing performed by each of the temporal integration computing sections  61   a   1 ,  61   a   2 , . . . ,  61   an  is presented below. 
     
       
         
           
             
               
                 
                   
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     The weighting function switching computing section  62  performs averaging according to the following formula (Formula 31) using the respectively supplied evaluation functions S FK  to determine an evaluation function S SUM , and further, using the evaluation function S SUM , obtains a weighting function φ for the entire manipulator  20  by performing computational processing based on Formula 32. Formulas 31 and 32 are provided below. 
     
       
         
           
             
               
                 
                   
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     The weighting function tables  62   a  used in the above second embodiment may be provided in the weighting switching computing section  62 A, whereby a weighting function in at least one of the weighting function tables and a weighting function φ Fi  obtained by the computational processing may be switchably used as needed. As a result, a wide range of bending control can be performed depending on the insertion state of the insertion portion  9 . 
     Therefore, according to the first variation, as described above, since a weighting function φ Fi  that enables a contact state with the intestinal wall or the like to be avoided is obtained with respect to the entire manipulator  20  and angles of the plurality of link members  21   a  are controlled, bending movement is performed on the entire manipulator  20  at angles enabling the entire manipulator  20  to avoid the intestinal wall even in the case where, upon insertion of the insertion portion  9  into a tube cavity, the bending portion  14  of the insertion portion  9  comes into contact with the intestinal wall or the like in the tube cavity and the contact state continues. As a result, insertion can be performed more safely and in a smooth manner. 
     While a configuration using a detection result of the load detecting section  60  has been described with respect to the first variation, the present embodiment is not limited to such a configuration. Instead, it is also possible to obtain a weighting function for the entire manipulator  20  regardless of the availability of the tension sensor that is the load detecting section  60 . Such a second variation will be presented below. 
       FIGS. 48 and 49  are for describing a second variation of the second embodiment, wherein:  FIG. 48  is a graph showing characteristics of a detection result from an actuator control block and time; and  FIG. 49  is a block diagram showing a configuration of a substantial part including the weighting switching computing section in the dynamics computing section. The ordinate shown in  FIG. 48  represents a displacement (P) of an angle by which each link member  21   a  moves obtained from a sensor; the abscissa represents time (t); and axes  1  and  2  respectively indicate first and second link members  21   a.    
     As shown in  FIG. 48 , in the same manner as in the first variation, during insertion of the insertion portion  9  of the endoscope apparatus  1  into a tube cavity, for example, the displacement value (P) of the second link member  21   a   2  from the sensor  38  (refer to  FIGS. 10 and 11 ) decreases as time advances, while the displacement value (P) of the first (distal end-side) link member  21   a   1  from the sensor  38  increases after reaching a given predetermined point in time. 
     In other words, this indicates that the first link member  21   a   1  came into contact with the intestinal wall of the large intestine or the like at the given predetermined point in time, thereby causing the displacement value to increase with time, and, subsequently, since the contact state of the link member  21   a   1  with the intestinal wall has continued, rotational movement of the distal end-side link member  21   a   1  has caused an further increase in the displacement value of the angle by which the link member  21   a   1  moves. 
     In consideration thereof, the present embodiment is arranged to perform computational processing to determine a weighting function capable of avoiding such a contact state based on the displacement value detected at that point even when a contact state of an arbitrary link member  21   a  with the intestinal wall continues. In other words, it is arranged so that, when determining angles of the plurality of link members  21   a , a weighting function that weights the entirety of the plurality of link members  21   a  or, in other words, the entire manipulator  20  is created instead of a weighting function for each of the link members  21   a  as was used in the second embodiment. 
     More specifically, as shown in  FIG. 49 , temporal integration computing sections  61 A 1 ,  61 A 2 , . . . ,  61 An respectively provided at each of the plurality of link members  21   a  are arranged to be connected to the weighting function switching computing section  62 B in the dynamics computing section  43 . 
     Displacement values P 1 , P 2 , . . . , Pn from the sensor  38  in the actuator control block  31  provided in the respective link members  21   a  are respectively supplied to each of the temporal integration computing sections  61 A 1 ,  61 A 2 , . . . ,  61 An. 
     The temporal integration computing section  61 A 1  performs temporal integration computation processing for obtaining an evaluation function using the supplied displacement value P 1 , and outputs an obtained evaluation function SP 1  to the weighting function switching computing section  62 B. 
     Temporal integration computation processing is performed in the same manner by the temporal integration computing sections  61 A 2 , . . . ,  61 An to respectively determine evaluation functions SP 2 , . . . , SPn to be outputted to the weighting function switching computing section  62 B. 
     A formula based on computational processing performed by each of the temporal integration computing sections  61 A 1 ,  61 A 2 , . . . ,  61 An is presented below. 
     
       
         
           
             
               
                 
                   Evaluation 
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     The weighting function switching computing section  62 B performs averaging according to Formula 34 below using the respectively supplied evaluation functions S PK  to determine an evaluation function S SUM , and further, using the evaluation function S SUM , obtains a weighting function φ i  for the entire manipulator  20  by performing computational processing based on Formula 35. Formulas 34 and 35 are provided below. 
     
       
         
           
             
               
                 
                   
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     The weighting function tables  62   a  used in the above second embodiment may be provided in the weighting function switching computing sections  62 A and  62 B, whereby a weighting function in at least one of the weighting function tables and a weighting function φ i  obtained by the above-mentioned computational processing may be switchably used as needed. As a result, a wide range of bending control can be performed depending on the insertion state of the insertion portion  9 . 
     Therefore, as described above, it is now possible to obtain a weighting function φ i  with respect to the entire manipulator  20  that enables a contact state with the intestinal wall or the like to be avoided without a tension sensor that is the load detecting section  60  provided. By controlling the angles of the plurality of link members  21   a  using the weighting function φ i , since bending movements are performed by the entire manipulator  20  in the same manner as in the first variation at angles enabling the entire manipulator  20  to avoid the intestinal wall even in the case where, upon insertion of the insertion portion  9  into a tube cavity, the bending portion  14  of the insertion portion  9  comes into contact with the intestinal wall or the like in the tube cavity and the contact state continues, insertion can be performed more safely and in a smoother manner. 
     As described above, according to the present second embodiment, since the distal end-side link member  21   a   1  among the plurality of link members  21   a  constituting the bending portion  14  of the insertion portion  9  can be point-locked, and attitude control can be performed over the other link members  21   a  so that arbitrary attitudes having redundancy can be assumed, it is now possible to insert the bending portion  14  of the insertion portion  9  in a shape conforming to the interior shape of a tube cavity. As a result, advantageous effects such as improvement of insertability of the insertion portion can be achieved. 
     In addition, the endoscope apparatus  1  according to the present second embodiment enables automatic determination of an optimum weighting function based on a detection result of a load detecting section  60  in the case where, when inserting the bending portion  14  into a tube cavity, computational processing is performed using a weighting function on angles of a plurality of link members  21   a  constituting the bending portion  14  or on an angle of an arbitrary link member  21   a  among the plurality of link members  21   a . Consequently, since forced attitudes of the plurality of link members  21   a  or the manipulator  20  can be eliminated and an angle necessary for enabling movement in a mobile range can be acquired for each of the plurality of link members  21   a , it is now possible to perform insertion into a tube cavity in a smooth manner. 
     For the present embodiment, while point-locking a two-dimensional position and direction of the distal end-side link member  21   a   1  among the plurality of link members  21   a  has been described, the present invention is not limited to this example. Instead, the present invention may be configured so that a three-dimensional position and direction are point-locked. 
     For the present embodiment, while the bending portion  14  having the insertion portion driving mechanism  20  constituting a manipulator has been described as being provided at the insertion portion  9  of the endoscope  2 , the bending portion  14  may be arranged to be provided at an insertion portion of an endoscope insertion aiding device that aids the insertion of the insertion portion  9  into a tube cavity by allowing insertion of the insertion portion  9  of the endoscope  2 . 
     Next, a third embodiment of the present invention will be described with reference to  FIGS. 50 to 57 . The present third embodiment primarily differs from the above first embodiment in that bending movement of the bending portion  14  is performed by respectively rotationally moving the plurality of link members  21   a  by respectively pulling or relaxing a plurality of bending operation wires  130 A ( 130 A 1 ,  130 A 2 , . . . ,  130 An). Otherwise, descriptions on points similar to the first embodiment described above will be omitted. 
       FIG. 50  is a top view showing a configuration of a bending portion whose driving mechanism is constituted by a bending operation wire, a driving pulley and a free pulley;  FIG. 51  is a side view showing a suspended state of a bending operation wire provided between respective link members of the bending portion shown in  FIG. 50 ;  FIG. 52  is a configuration diagram showing a configuration of a driving pulley provided with the driving shaft shown in  FIG. 50 ; and  FIG. 53  is a top view showing a configuration of the free pulley shown in  FIG. 50 . 
     The present third embodiment is arranged so that the driving section  10   b  is disposed inside the operation section  10 , and a plurality of motors  27  of the driving section  10   b  is connected through the inside of the insertion portion  9  to the respective bending operation wires  130 A. 
     The driving section  10   b  (respective motors  27 ) respectively rotationally moves the plurality of link members  21   a   1 ,  21   a   2 , . . . ,  21   an  by pulling or relaxing the plurality of bending operation wires  130 A 1 ,  130 A 2 , . . . ,  130 An. 
     The bending operation wires  130 A 1  to  130 An are arranged to be connected to driving shafts of the motors  27  via gears and sprockets, not shown. The bending operation wires  130 A 1  to  130 An are extended in the insertion portion  9 , and proximal end portions thereof are suspended by a driving pulley  123  and a free pulley  125  of a rearmost end-side link member  21   an  among the plurality of link members  21   a   1 ,  21   a   2 , . . . ,  21   an . As will be described later, the respective intervals between the link member  21   an  and the other link members  21   a   1 , . . . ,  21   a (n−1) are arranged to be suspended by other bending operation wires  131   a   1 ,  131   a   2 , . . . ,  131   am  (where m is a natural number). 
     Consequently, the rotational forces of the respective motors  27  are arranged to be transmitted to the plurality of link members  21   a  via the bending operation wires  130 A 1  to  130 An, the driving pulley  123 , the free pulley  125  and the bending operation wires  131   a   1  to  131   am.    
     The numbers of the link members  21   a  and the joint members  21   b  are not limited to the configuration examples shown in the drawings, and configurations are also possible wherein the numbers thereof are increased or decreased in accordance with the intended use of the endoscope  2 . The link member  21   a   1  is disposed on a most distal end-side of the distal end portion  13 , and is arranged so that link members  21   a   2 ,  21   a   3 , . . . ,  21   an  are sequentially connected to a rear end-side thereof. As a result, the joint members  21   b   1 ,  21   b   2 ,  21   b   3 , . . . ,  21   bn  are also respectively disposed between the link members  21   a  in sequence from the distal end portion  13  side. 
     A specific configuration of the bending portion  14  is shown in  FIG. 50 . The example shown in  FIG. 50  is a case where n=4, and where the insertion portion driving mechanism  20  is constituted using four link members  21   a   1  to  21   a   4 . 
     As shown in  FIG. 50 , by pulling or relaxing the bending operation wires  130 A 1  to  130 A 4  and  131   a   1  to  131   a   6 , the plurality of link members  21   a   1 ,  21   a   2 ,  21   a   3  and  21   a   4  are respectively consecutively connected so as to be rotationally movable by the insertion portion driving mechanism  20  of the bending portion  14 . 
     The plurality of link members  21   a   1  to  21   a   4  are respectively connected so as to be rotationally movable by a driving shaft  124  that is the joint members  21   b   1  to  21   b   4 . The driving shaft  124  is a shaft member integrally configured with the driving pulley  123 , to be described later. A potentiometer, not shown, is mounted as first detecting section on the driving shaft  124 . 
     The potentiometer is arranged to detect a rotational quantity of the driving shaft  124  and output the same as a state quantity detection signal of the link member  21   a  to the controller  5  via a signal wire, not shown. The potentiometer as first detecting section may be configured so as to be provided on, for example, a sprocket (not shown) for transmitting the rotational force of a motor  27  provided on the driving section  10   b  side to a bending operation wire. 
     Connecting grooves  122  for pivotally supporting so as to be rotationally movable and housing a connecting protruding portion  122 A formed on a link member  21   a  of a subsequent stage are respectively provided on the plurality of link members  21   a   1  to  21   a   4 . The driving shaft  124  is fitted and fixed into a hole provided on the connecting protruding portion  122 A in a state where the connecting protruding portion  122 A is mounted on the connecting groove  122  of the subsequent-stage link member  21   a  to enable the link member  21   a  to be connected so as to be rotationally movable. 
     A driving shaft  124  that pivotally supports the connecting groove  124  and the connecting protruding portion  122 A of the second link member  21   a   2  is fitted and fixed to the proximal end-side of the most distal end-side link member  21   a   1 . A driving pulley  123  is integrally formed on the proximal end portion on one side of the driving shaft  124 . The driving pulley  123  is arranged to be fixed to a lateral face of the distal end-side link member  21   a   1 . 
     As shown in  FIG. 52 , the driving pulley  123  having the driving shaft  124  is arranged to create rotational force when the bending operation wire  131   a   6  is suspended and, at the same time, either pulled or relaxed, and the driving shaft  124  is integrally provided to the lower side of the center of the driving pulley  123 . 
     The length of the driving shaft  124  of the driving pulley  123  is formed to be elongated in consideration of a required thickness when stacking the free pulleys  125 , to be described later, in sequence from the distal end-side link member  21   a   1 , the second-stage link member  21   a   2 , the third-stage link member  21   a   3 , and the fourth-stage link member  21   a   4 . 
     The bending operation wire  131   a   6  is suspended by a driving pulley  123  fixed to the distal end-side link member  21   a   1 . The other side of the bending operation wire  131   a   6  is suspended by a free pulley  125  disposed on the same side of the second-stage link member  21   a   2  and which is pivotally supported so as to be rotationally movable by the driving shaft  124 . 
     As for the free pulley  125 , two pulleys are annexed as shown in  FIGS. 50 and 53 , and is configured with a hole  125   a  into which the driving shaft  124  is inserted. The free pulley  125  is pivotally supported so as to be rotationally movable by the driving shaft  124  of the driving pulley  123  fixed to the other side of the second-stage link member  21   a   2 . The two pulleys of the free pulley  125  respectively support the bending operation wires  131   a   6  and  131   a   4  from both the driving pulley  123  of the distal end-side link member  21   a   1  and the free pulley  125  provided at the third-stage link member  21   a   3 . 
     A driving pulley  123  is fixed to the opposite side of the free pulley  125  of the second-stage link member  21   a   2 . The bending operation wire  131   a   5  is suspended by the driving pulley  123 . The other side of the bending operation wire  131   a   5  is suspended by a free pulley  125  disposed on the same side of the third-stage link member  21   a   3  and which is pivotally supported so as to be rotationally movable by the driving shaft  124 . 
     The bending operation wire  131   a   3  is suspended by the other pulley of the free pulley  125 . The other side of the bending operation wire  131   a   3  is suspended by a free pulley  125  disposed on the same side of the fourth-stage link member  21   a   4  and which is pivotally supported so as to be rotationally movable by the driving shaft  124 . 
     A driving pulley  123  is fixed via the free pulley  125  to the opposite side of the free pulley  125  of the third-stage link member  21   a   3 . The bending operation wire  131   a   1  is suspended by the driving pulley  123 . The other side of the bending operation wire  131   a   1  is suspended by a free pulley  125  disposed on the same side of the fourth-stage link member  21   a   4  and which is pivotally supported so as to be rotationally movable by the driving shaft  124 . The bending operation wire  131   a   2  is suspended by the other pulley of the free pulley pivotally supported so as to be rotationally movable by the driving pulley  123 . The other side of the bending operation wire  131   a   2  is suspended by a free pulley  125  disposed on the same side of the fourth-stage link member  21   a   4  and which is pivotally supported so as to be rotationally movable by the driving shaft  124 . 
     Two free pulleys  125  respectively suspending the bending operation wires  131   a   1  and  131   a   4  to one of the pulleys are pivotally supported by the driving shaft  124  on one side of the fourth-stage link member  21   a   4 . Bending operation wires  130 A 1  and  130 A 2  extended via the inside of the insertion portion  9  are arranged to be suspended by the two free pulleys  125 . 
     A free pulley  125  suspending the bending operation wire  130 A 3  to one of the pulleys is pivotally supported by the driving shaft  124  on the opposite side of the fourth-stage link member  21   a   4 . A driving pulley  123  integrally configured with the driving shaft  125  is disposed on the outer side of the free pulley  125 . The driving pulley  123  is fixed to the fourth-stage link member  21   a   4  via the free pulley  125 . A bending operation wire  130 A 3  extended via the inside of the insertion portion  9  is arranged to be suspended by the free pulley  125 . A bending operation wire  130 A 4  extended in the same manner via the inside of the insertion portion  9  is arranged to be suspended by the driving pulley  123 . 
     As shown in  FIG. 51 , the bending operation wires  131   a   1  to  131   a   6  are arranged to be suspended in respective crossed states by the driving pulley  123  or the free pulley  125  between each corresponding link member  21   a.    
     To describe bending movements of the bending portion  14  attributable to the pulling of the bending operation wires  130 A 1  to  130 A 4 , for example, when the bending operation wire  130 A 4  shown in  FIG. 50  is pulled by a rotational force F 4 , since the driving pulley  123  supporting the bending operation wire  130 A 4  is fixed to the fourth-stage link member  21   a   4 , the fourth-stage link member  21   a   4  is to be rotationally moved. 
     When an opposite-side bending operation wire  130 A 1  is pulled by a rotational force F 2  in a state where the bending operation wire  130 A 4  is immobilized, the rotation of the free pulley  125  that is suspended by the bending operation wire  130 A 1  causes the bending operation wire  131   a   1  suspended by the free pulley  125  to be pulled. The rotational force is transmitted to the driving pulley  123  of the third-stage link member  21   a   3  by which the bending operation wire  131   a   1  is suspended to cause rotational movement of the third-stage link member  21   a   4 . 
     When the bending operation wire  130 A 3  is pulled by a rotational force F 3  in a state where the bending operation wires  130 A 4  and  130 A 1  are immobilized, the rotation of the free pulley  125  that is suspended by the bending operation wire  130 A 3  causes the bending operation wire  131   a   3  suspended by the free pulley  125  to be pulled. The rotational force is transmitted to the free pulley  125  of the third-stage link member  21   a   3  by which the bending operation wire  131   a   3  is suspended. Rotation of the free pulley  125  causes the bending operation wire  131   a   5  that is suspended by the free pulley  125  to be pulled. The rotational force is transmitted to the driving pulley  123  of the second-stage link member  21   a   2  by which the bending operation wire  131   a   5  is suspended to cause rotational movement of the second-stage link member  21   a   2 . 
     Further, when the bending operation wire  130 A 2  is pulled by a rotational force F 1  in a state where the bending operation wires  130 A 4 ,  130 A 1  and  130 A 3  are immobilized, the rotation of the free pulley  125  that is suspended by the bending operation wire  130 A 2  causes the bending operation wire  131   a   2  suspended by the free pulley  125  to be pulled. In the same manner as described above, the rotational force is transmitted to the driving pulley  123  of the distal end-side link member  21   a   1  via the free pulley  125  of the third-stage link member  21   a   3  by which the bending operation wire  131   a   2  is suspended, the bending operation wire  131   a   4 , the free pulley  125  of the second-stage link member  21   a   2 , and the bending operation wire  131   a   6 . Consequently, the rotation of the driving pulley  123  cases rotational movement of the distal end-side link member  21   a   4 . 
     As seen, by performing appropriate rotational control of the rotational forces F 1  to F 4  of the respective motors  27  in the driving section  10   b  so as to pull or relax the bending operation wires  130 A 1  to  130 A 4 , it is possible to rotationally move a plurality of link members or only a designated link member  21   a.    
     Since an endoscope apparatus having a multi-joint link structure is arranged to bend the bending portion  14  by controlling pulling or relaxing of bending operation wires, there may be cases where bending movement is affected by interference from a bending operation wire between link members  21   a . Such a problem will be described with reference to  FIGS. 50 ,  54  and  55 . 
       FIGS. 54 to 56  are explanatory diagrams for explaining problem areas of a case where bending movements of a multi-link member  21   a  is performed by pulling or relaxing bending operation wires, wherein:  FIG. 54  shows a state when a plurality of link members is not performing bending movements;  FIG. 55  shows a state in which the distal end-side link member inadvertently bends due to interference when a second-stage link member is bent by 90 degrees; and  FIG. 56  shows a state in which correction processing by 90 degrees in the opposite direction is performed by the controller according to the present invention from the state shown in  FIG. 55 .  FIG. 57  is a block line diagram showing a configuration of a servo controller in each actuator control block according to the present embodiment. 
     The arrows indicating the positions of the driving pulley  123  and the free pulley  125  in  FIGS. 54 and 55  are for explanatory purposes and indicate a direction of rotational movement of each link member. The shaded area on the left hand side of the diagrams indicate opposite side portions of each link member of the bending portion  14 . 
     For example, as shown in  FIG. 54 , let us assume that, from a state where the bending portion  14  of the insertion portion  9  is not bent and each of the link members  21   a   1  to  21   a   4  is also not bent, the operator performs bending operation of the second-stage link member  21   a   2  so as to bend the same 90 degrees in the direction of arrow A as shown in the diagram. 
     In this case, as shown in  FIG. 50 , by pulling the bending operation wire  130 A 3  by the rotational force F 3  in a state where the bending operation wires  130 A 4  and  130 A 1  are immobilized, rotational force is transmitted to the driving pulley  123  fixed to the second-stage link member  21   a   2  via the bending operation wires  130 A 3 ,  131   a   3 , the free pulley  125  and the bending operation wire  131   a   5 , and, for example, the second-stage link member  21   a   2  bends 90 degrees in the direction of arrow A as shown in the diagram. 
     However, at this point, since the bending operation wires  130 A 1 ,  130 A 2 ,  131   a   1 ,  131   a   2 ,  131   a   4  and  131   a   6  (refer to  FIG. 50 ) are respectively in immobilized states, the bending movement of the second-stage link member  21   a   1  creates a force at the driving pulley  123  and the free pulley  125  respectively suspending the bending operation wires  130 A 1 ,  130 A 2 ,  131   a   1 ,  131   a   2 ,  131   a   4  and  131   a   6  which attempts to bend the driving pulley  123  and the free pulley  125  in the direction of the arrows shown in the shaded area on the left hand side of the diagram. 
     As shown in  FIG. 50 , since the distal end-side link member  21   a   1  is connected to the free pulley  125  of the second-stage link member  21   a   2  via the bending operation wire  131   a   6  suspended by the driving pulley  123 , the force created at the free pulley  125  by the bending movement of the second-stage link member  21   a   2  interferes with the bending operation wire  131   a   6 . As a result, as shown in  FIG. 55 , the distal end-side link member  21   a   1  will be inadvertently bent in the direction of the arrow C shown in the diagram with respect to the second-stage link member  21   a   2 . 
     However, in the case where the distal end-side link member  21   a   1  is bent as a result of a bending movement of an intermediate link member  21   a  as described above, as shown in  FIG. 56 , the endoscope apparatus  1  according to the present embodiment is capable of performing correction control so as to cause a bending movement of the distal end-side link member  21   a   1  in the opposite direction (the direction of an arrow D shown in the diagram) by an angle corresponding to the bent angle (90 degrees). A schematic internal configuration of an actuator control block capable of such bending correction control is shown in  FIG. 57 . 
     As described with reference to  FIGS. 9 to 12  for the above first embodiment, the endoscope apparatus  1  according to the present third embodiment includes actuator control blocks  31   a   1  to  31   an  corresponding to the respective link members  21   a . A servo controller  36 A is respectively provided at the actuator control blocks  31   a   1  to  31   an.    
     As described with reference to  FIG. 12  for the above first embodiment, the servo controller  36 A includes a PD control section  40 . As shown in  FIG. 57 , the present embodiment is further provided with a position command variation correcting section  160  that acquires a servo command value signal (including displacement information from the motor  27 ) supplied to the PD control section  40 , calculates an opposite-direction position command variation correction quantity from the servo command value signal, and adds the opposite-direction position command variation correction quantity with the servo command value signal and supplies the sum to a PD control section  40  of a subsequent stage. 
     In  FIG. 57 , PD control sections  40  of the respective stages are indicated by reference characters  40 A 1  to  40 An assigned thereto, and position command variation correcting sections  160  of the respective stages are indicated by reference characters  160 A 1  to  160 An assigned thereto. More specifically, in the present embodiment, as shown in  FIG. 57 , assuming that the PD control section  40  corresponding to the distal end-side link member  21   a   1  (nearest end-side link member) is first PD control section  40 A 1 , the PD control section  40  corresponding to the subsequent-stage (second-stage) link member  21   a   2  (intermediate-side link member) is second PD control section  40 A 2 , . . . , and the PD control section  40  corresponding to the furthest end-side link member  21   an  is Nth PD control section  40 AN, position command variation correcting sections  160 A 1 ,  160 A 2 , . . . ,  160 A(N−1) are respectively provided between the respective PD control sections  40 A  1 ,  40 A 2 , . . . ,  40 AN. 
     For example, the first position command variation correcting section  160 A 1  calculates a position command variation that is opposite in direction to the distal end-side link member  21   a   1  from the supplied servo command value signal and the displacement information of the motor  27 , and outputs the same to the input side of the subsequent-stage second PD control section  40 A 2 . 
     Then, a servo command value signal to which is added the position command variation from the first position command variation correcting section  160 A 1  is supplied to the second PD control section  40 A 2 , which in turn creates an operation output value signal (that is a driving signal, and which is indicated in the diagram as an intermediate-side link member driving signal) through PD control such as proportional/differential control based on the servo command value signal, and provides the same to a corresponding motor  27 . 
     The second position command variation correcting section  160 A 2  calculates a position command variation that is opposite in direction to the second-stage link member  21   a   2  from the servo command value signal supplied to the second PD control section  40 A 2 , and outputs the same to the input side of, for example, the third PD control section  40 A 3  of the subsequent stage. 
     Then, a servo command value signal to which is added the position command variation from the second position command variation correcting section  160 A 2  is supplied to the third PD control section  40 A 3 , which in turn creates an operation output value signal (that is a driving signal, and which is indicated in the diagram as a farthest end-side link member driving signal) through PD control such as proportional/differential control based on the servo command value signal, and provides the same to a corresponding motor  27 . 
     As shown, in the present embodiment, a position command variation that is opposite in direction to the link member  21   a  is sequentially added to the servo command value signal of the subsequent-stage link member from the nearest end-side link member via intermediate-side link members towards the furthest end-side link member, whereby rotational control of the motor  27  is performed based on obtained driving signals. 
     In other words, in the case where the distal end-side link member  12   a   1  is inadvertently bent by 90 degrees as a result of a bending movement of an intermediate link member  21   a  as shown in  FIG. 55 , the servo controller  36 A according to the present embodiment performs correction control so as to cause bending movement of the subsequent-stage link member  21   a   2  in the opposite direction by an angle (90 degrees) corresponding to the angle by which the distal end-side link member  21   a   1  was bent. Then, in the same manner, the servo controller  36 A performs correction control so as to cause bending movement of the subsequent-stage link member  21   a   3  and thereafter in the opposite direction by an angle corresponding to the angle by which the previous-stage link member  21   a  was bent. 
     Consequently, during bending operation of an arbitrary link member  21   a , even when a distal end-side link member  21   a  is bent due to interference of a bending operation wire between the respective link members  21   a , correction can be performed so as to reliably return the distal end-side link member  21   a   1  to its original position. Therefore, it is now possible to maintain a position of the distal end portion  13  based on an operation signal. 
     The controller  5  is capable of further enhancing the insertability of the insertion portion  9  by performing stiffness control so as to vary the stiffness of the entire insertion portion  9  including the bending portion  14 . Such a fourth embodiment is shown in  FIGS. 58 to 60 . 
       FIGS. 58 to 60  are related to the fourth embodiment, wherein:  FIG. 58  is a configuration diagram showing a configuration of an entire endoscope apparatus according to the fourth embodiment;  FIG. 59  is an explanatory diagram explaining characteristics of a bending portion when bending driving is performed thereon by a controller; and  FIG. 60  is an explanatory diagram explaining characteristics of a bending portion when stiffness control is performed thereon by a controller according to the second embodiment. For the present fourth embodiment, a description will be given on the assumption that an endoscope  2  is provided which is capable of bending the bending portion  14  in two directions, namely, upward and downward. 
     As shown in  FIG. 58 , an endoscope apparatus  1  includes a controller  5  similar to that of the third embodiment, an operation command section  7 , a stiffness setting dial  207 , and the endoscope  2 . 
     The endoscope  2  includes: two motors  227   a  and  227   b  that are the driving section  10   b ; two gears  261   a  and  261   b  for transmitting the rotational force of each of the motors  227   a  and  227   b ; sprockets  262   a  and  262   b  that meshes with the two gears  261   a  and  261   b  and rotates so as to respectively pull or relax bending operation wires  230   a  and  230   b ; a bending portion  14  in which the bending operation wires  230   a  and  230   b  are extended in an insertion portion  9  and which is bendable in two directions, namely, upward and downward, by the pulling or relaxing of the bending operation wires  230   a  and  230   b ; and a distal end portion  13 . 
     Although not shown, potentiometers that detect a rotational quantity of each motor  227   a ,  227   b  are provided at the sprockets  262   a  and  262   b . Detection results from the potentiometers are arranged to be fed back to the controller  5 . 
     The stiffness setting dial  207  is operation section for setting a stiffness level of the bending portion  14  or the entire insertion portion  9  including the bending portion  14 , and outputs a stiffness setting level signal based on an operation of the operator to the controller  5 . 
     While the configuration of the controller  5  is approximately the same as that of the third embodiment, when the stiffness setting dial  207  is operated during bending control of the bending portion  14  based on an operation command value signal by the operation command section  7 , stiffness of the bending portion  14  or the entire insertion portion  9  including the bending portion  14  performing a bending movement is controlled based on the stiffness setting level signal. 
     Stiffness control of the bending portion  14  or the entire insertion portion  9  will now be described with reference to  FIGS. 59 and 60 . 
       FIG. 59  shows a state where downward bending driving is performed on the bending portion  14  by the controller  5  as a dynamic simplified model. In  FIG. 59 , for simplicity, the states of the bending operation wires (pulling wires)  230   a  and  230   b  are handled as spring models in which respective end points thereof are fixed to the distal end portion of the endoscope. In other words, as shown in  FIG. 59 , load quantities applied to the bending operation wires  230   a  and  230   b  are simulated by the springs  200   a  and  200   b . In the diagram, when only the motor  227   b  is being driven, a force pulling the spring  200   b  on the bending operation wire  230   b  side exceeds a force pulling the spring  200   a  on the bending operation wire  230   a  side. As a result, the bending portion  14  bends downward. 
     In the present embodiment, after causing movement of the bending portion  14  into a predetermined bent shape, for example, as shown in  FIG. 60 , by rotationally controlling the opposite-side motor  227   a  in the same manner as the motor  227   b , the motor  227   a  is rotationally controlled so that the force pulling the spring  200   a  of the bending operation wire  230   a  side becomes equal to the force pulling the spring  200   b  on the bending operation wire  230   b  side. 
     Consequently, since both pulling wires  230   a  and  230   b  have end points fixed to the distal end portion of the endoscope according to the present embodiment, a compression force will be applied to the entire insertion portion of the endoscope as a result of the force pulling the spring  200   a  of the bending operation wire  230   a  side and the force pulling the spring  200   b  on the bending operation wire  230   b  side. At this point, even when the force is applied to both parts, the force will be applied while maintaining positions of the wires by adopting position control as the method of wire pulling control. 
     It should be noted that, since the springs depicted in  FIGS. 59 and 60  are dynamic model expressions of pulling wires, characteristics will reflect those of the wires themselves. 
     Therefore, the bending portion  14  assumes a stiffness state in which the bending shape thereof is retained. In addition, since the bending operation wires  230   a  and  230   b  are disposed inside the insertion portion  9 , the entire insertion portion  9  will also attain stiffness. 
     The stiffness setting dial  207  is arranged so that levels of forces respectively pulling the springs  200   a  and  200   b  on the sides of the bending operation wires  230   a  and  230   b  are switchable and settable in phases. Therefore, during bending driving, the controller  5  is able to perform control so that the stiffness level of the bending portion  14  or the entire insertion portion  9  including the bending portion  14  is appropriately varied. 
     Consequently, according to the fourth embodiment, since the stiffness of the bending portion  14  or the entire insertion portion  9  including the bending portion  14  can be controlled, insertability of the insertion portion  9  can be improved by performing stiffness control of the bending portion  14  or the entire insertion portion  9  during insertion. 
       FIGS. 61 to 65  are for explaining a first variation of the fourth embodiment, wherein:  FIG. 61  is a configuration diagram showing a configuration of an entire endoscope apparatus according to a fourth variation;  FIG. 62  is a block diagram showing a specific internal configuration of a servo controller;  FIG. 63  is an explanatory diagram explaining characteristics of a bending portion when stiffness control is performed thereon by a controller according to the fourth embodiment;  FIG. 64  is a block line diagram showing a bending control section shown in  FIG. 62 ; and  FIG. 65  is a block line diagram showing a control section for stiffness control shown in  FIG. 62 . 
     As shown in  FIG. 61 , with the endoscope apparatus  1  according to the first variation, the stiffness setting dial  207  used in the above fourth embodiment has been deleted while tension sensors  263   a  and  263   b  are respectively provided which detect respective tension states of the bending operation wires  230   a  and  230   b  and output the same to the controller  5 . 
     In other words, by respectively providing the tension sensors  263   a  and  263   b , it is now possible to detect a stiffness state of the bending portion  14  or the entire insertion portion  9  including the bending portion  14  when stiffness control is being performed. 
     The controller  5  acquires detection results by the tension sensors  263   a  and  263   b  or, in other words, tension F/B information, and when stiffness control is being performed, controls rotational driving of each of the motors  227   a  and  227   b  based on stiffness command information instructed by the operation command section  7  and the tension F/B information to perform stiffness control of the bending portion  14  or the entire insertion portion  9 . 
     The controller  5  is also capable of performing position command control of the bending portion  14  in the same manner as in the fourth embodiment, and, as a result, is capable of executing either one of the modes of position command control and stiffness command control. 
     More specifically, the operation command section  7  is provided with mode designating section (not shown) that designates a mode representing bending position command control and a mode representing stiffness command control and outputs designated mode command information. Mode command information from the mode designating section is to be outputted to the servo controller  36 A in the controller  5 . 
       FIG. 62  shows a specific internal configuration of the servo controller  36 A respectively provided at each motor  227   a  and  227   b.    
     As shown in  FIG. 62 , the servo controller  36 A according to the first variation includes: a mode discriminating section  270  that discriminates whether the current mode is the bending position command control mode or the stiffness command control mode based on mode command information from the mode designating section of the operation command section  7 ; a PID control section  271  (refer to  FIG. 64 ) that is a bending control section that creates and outputs an operation output value signal (that is a driving signal and which is also referred to as a motor position command signal) for bending position command control which is necessary for executing the bending position command control mode based on position command information (servo command value signal) and position F/B information; a P control section  272  (refer to  FIG. 65 ) that is a control section for stiffness control that creates and outputs an operation output value signal (that is a driving signal and also referred to as a motor position command signal) for stiffness command control which is necessary for executing the stiffness command control mode based on stiffness command information and tension F/B information; and a switching section  264  that selectively outputs either one of an output of the PID control section  271  or an output of the P control section  272  based on the discrimination result of the mode discriminating section  270  and outputs the same to a relevant motor  227   a ,  227   b.    
     Accordingly, when the discrimination result of the mode discriminating section  270  is the bending position command control mode, the switching section  264  outputs a driving signal (motor position command signal) from the PID control section  271  that is a bending control section to the designated motor  227   a  or  227   b.    
     In this case, as shown in  FIG. 64 , the PID control section  271  that is the bending control section creates and outputs a driving signal (also referred to as a motor position command signal) for bending position command control through PD control such as proportional/differential control based on position command information (servo command value signal) and position F/B information. Consequently, bending movement of the bending portion  14  based on position command information is caused when the driving signal for bending position command control is supplied to the designated motor  227   a  or  227   b  via the switching section  264  and driving of the motor  227   a  or  227   b  is controlled. 
     On the other hand, when the discrimination result of the mode discriminating section  270  is the stiffness command control mode, the switching section  264  outputs a driving signal (motor position command signal) from the P control section  272  that is a control section for stiffness control to the designated motor  227   a  or  227   b.    
     In this case, as shown in  FIG. 65 , the P control section  272  that is the control section for stiffness control creates and outputs a driving signal (also referred to as a motor position command signal) for stiffness command control through P control such as proportional control based on stiffness command information supplied from the operation command section  7  and tension F/B information. Consequently, stiffness of the bending portion  14  is controlled in a state where the attitude (bending direction) thereof during bending driving is maintained as described with respect to the fourth embodiment when a driving signal for stiffness command control is supplied to the designated motor  227   a  or  227   b  via the switching section  264  to control driving and, at the same time, a driving signal for bending position command control is supplied to the other motor  227   b  or  227   a.    
     As described with respect to the fourth embodiment, during execution of the stiffness command control mode, for example, when a driving signal for stiffness command control is supplied to the motor  227   a  to drive the same, a driving signal for bending position command control is invariably supplied to the other motor  227   b  to drive the same. 
     In other words, as shown in  FIG. 63 , by equalizing the pulling force of the spring  200   b  on the side of the bending operation wire  230   b  connected to the motor  227   b  during bending driving and the pulling force of the spring  200   a  on the side of the bending operation wire  230   a  connected to the motor  227   a  during stiffness changing driving, the bending portion  14  attains a state where stiffness is acquired while retaining the bending shape thereof in the same manner as in the fourth embodiment. 
     Therefore, according to the present variation, it is now possible to perform stiffness command control in a state where bending position command control of the bending portion  14  is performed, thereby enabling insertability of the insertion portion  9  to be even more enhanced than in the second embodiment. 
       FIGS. 66 and 67  are diagrams explaining a second variation of the fourth embodiment, wherein;  FIG. 66  is a configuration diagram showing a configuration of an entire endoscope apparatus according to the fourth variation; and  FIG. 67  is an explanatory diagram explaining characteristics of a bending portion when stiffness control is performed thereon by a controller according to the second variation. For  FIGS. 66 and 67 , like components to the third and fourth embodiments and the first variation of the fourth embodiment are assigned like reference characters, and descriptions thereof will be omitted. Thus, only different parts will be described. 
     As shown in  FIG. 66 , the endoscope apparatus  1  according to the second variation combines the configurations of the second embodiment and the first variation, and is configured using a bending portion  14  having a multi-joint link structure approximately similar to that of the third embodiment. 
     In other words, the endoscope apparatus  1  according to the second variation includes the stiffness setting dial  207  and the tension sensors  263   a ,  263   b  in the same manner as the fourth embodiment, and further includes a bending portion  14  configured so as to include a plurality of link members  21   a   1  to  21   an  (where, for example, n=4) respectively bendable in two directions, namely, upward and downward. 
     In the same manner as the first variation, the controller  5  according to the second variation performs bending position command control and stiffness command control so that the bending portion  14  attains a stiffness state while retaining the bending direction (bending state) of the bending portion  14  during bending driving. However, the controller  5  is also capable of performing bending position command control and stiffness command control on an arbitrary designated link member  21   a  among a plurality of link members  21   a.    
     Characteristics of the bending portion  14  having a plurality of link members  21   a  of this case is shown in  FIG. 67 . In other words, as shown in  FIG. 67 , the bending portion  14  acquires characteristics represented by: two springs  200   a  and  200   b  indicating load quantities applied to two bending operation wires of the distal end-side link member  21   a   1 ; two springs  200   c  and  200   d  indicating load quantities applied to two bending operation wires of the second-stage link member  21   a   2 ; two springs  200   e  and  200   f  indicating load quantities applied to two bending operation wires of the third-stage link member  21   c ; and two springs  200   n  and  200   n  indicating load quantities applied to two bending operation wires of a subsequent member  21   an.    
     For example, when stiffness command control is performed during bending driving of the second-stage link member  21   a   2  and the third-stage link member  21   a   3 , forces respectively pulling the springs  200   c  and  200   d  of the link member  21   a   2  are equalized, and, at the same time, forces respectively pulling the springs  200   e  and  200   f  of the link member  21   a   3  are equalized. 
     However, since the configuration shown in  FIG. 67  is a physical model in which a plurality of springs counter each other, when actually attempting to perform stiffness command control of an arbitrary designated link member  21   a  among a plurality of link members  21   a  using the controller  5 , interference from a bending operation wire, a driving pulley and a free pulley disposed between the link member  21   a  and a link member  21   a  consecutively connected to the link member  21   a  occurs, thereby causing bending of the distal end-side link member  21   a   1 . 
     For this reason, a correction computing section, not shown, that performs computational processing for correcting bending movement of the distal end-side link member  21   a   1  when stiffness command control is performed on an arbitrary link member  21   a  is provided at the servo controller  36 A of the controller  5 . 
       FIG. 67  shows a principle model diagram, while  FIGS. 68A to 68C  show effect principle diagrams. More specifically:  FIG. 68A  is a principle diagram of a bending portion for explaining effects;  FIG. 68B  shows a state in which slack has occurred at a wire due to the shortening of tortuous tube length as a result of the pulling of a wire at a first bending portion; and  FIG. 68C  shows a state in which slack has occurred at a wire due to the shortening of tortuous tube length of a second bending portion as a result of the pulling of a wire at the second bending portion. 
     In  FIG. 68A , let us assume that, for example, the pulling wire  200   a  (refer to  FIG. 67 ) is pulled in order to drive the first bending portion. At this point, as shown in  FIG. 68B , tortuous tube length is shortened due to wire pulling of the pulling wire  200   a  and, at the same time, a compression force is applied to the second bending portion side. As a result, the wire pathways of the pulling wires  200   b  and  200   c  are shortened and a wire slack occurs. 
     In addition, when the pulling wire  200   b  is pulled in the state shown in  FIG. 68A  in order to drive the second bending portion, compression of the tortuous tube length of the second bending portion causes a similar slack on the pulling wire  200   a.    
     Consequently, driving affects bending portions other than the bending portion of which driving is desired. In other words, when there are a plurality of bending portions, correction is to be performed on bending portions other than the desired bending portion. 
     Next, a configuration and advantageous effects of the correction computing section will be described. 
     As for the correction method, as is described in the above fourth embodiment, wire load detecting section  263  is respectively disposed for each bending operation wire, and prior to the driving of a desired stiffness setting bending portion, a setting value storing section  274  (refer to  FIG. 69 ) that is means for storing a stiffness setting value other than the desired stiffness setting bending portion is incorporated. 
     As shown in  FIG. 69 , correction is performed by providing the setting value storing section  274  that stores data in addition to the respective inputting sections of position commands, stiffness commands and tension commands shown in the block line diagrams ( FIGS. 62 ,  64  and  65 ) described above. 
     At the setting value storing section  274 , stiffness setting of a desired bending portion is performed, and at the same time, a latch signal is activated at a driving section other than the desired bending portion to retain a value of a state prior to the stiffness setting. During stiffness setting at the desired bending portion, the setting value storing section  274  functions to pass command information to the control section  273  in real time. 
     This enables correction to be performed even when interference occurs at each bending portion. 
     In addition to performing bending correction of the distal end-side link member  21   a   1  during execution of stiffness command control, the correction computing section will also be able to perform computational processing for correcting bending movements of other link members  21   a  which are anticipated due to the execution of stiffness command control. 
     In the second variation, the controller  5  is arranged so that, when performing stiffness command control of the bending portion  14  having a plurality of link members  21   a , stiffness command control is performed so as to satisfy the following stiffness condition. 
     For example, assuming that the bending portion  14  is constituted by four link members  21   a   1  to  21   a   4 , a relationship among the respective stiffness levels of each link member  21   a  may be expressed as: 
     Fourth-stage link member  21   a   4 &gt;third-stage link member  21   a   3 &gt;second-stage link member  21   a   2 &gt;distal end-side link member  21   a   1 . 
     Therefore, as described above, with the endoscope apparatus according to the second variation, even if the bending portion  14  is configured so as to have a multi-joint link structure, it is now possible to perform stiffness command control on an arbitrarily designated link member  21   a  among the plurality of link members  21   a  in a state where bending position command control is performed on the bending portion  14  in the same manner as in the above third and fourth embodiments and the first variation of the fourth embodiment. 
     While two bending directions of upward and downward of the bending portion  14  have been described in the first variation, the present invention is not limited to this arrangement. Instead, the bending portion  14  may be configured so that bending movement is enabled in four bending directions of upward, downward, leftward and rightward, and at the same time, a motor that is the driving section  10   b  and a bending operation wire are provided. 
     For the third embodiment according to the present invention, while point-locking a two-dimensional position and direction of the distal end-side link member  21   a   1  among the plurality of link members  21   a  has been described, the present invention is not limited to this example. Instead, the present invention may be configured so that a three-dimensional position and direction are point-locked. 
     For the third embodiment according to the present invention, while the bending portion  14  having the insertion portion driving mechanism constituting a manipulator has been described as being provided at the insertion portion  9  of the endoscope  2 , the bending portion  14  may be arranged to be provided at an insertion portion of an endoscope insertion aiding device that aids the insertion of the insertion portion  9  into a tube cavity by allowing insertion of the insertion portion  9  of the endoscope  2 . 
     Next, a fifth embodiment of the present invention will be described with reference to  FIGS. 70 to 73 .  FIGS. 70 to 73  are diagrams explaining specific configurations and control operations of a servo controller according to the fifth embodiment of the present invention, wherein:  FIG. 70  is a block diagram showing a kinematics computing section included in a servo controller;  FIG. 71  is a block diagram showing an overall configuration of a servo controller provided at each actuator control block;  FIG. 72  is a block line diagram of the control block shown in  FIG. 71 ; and  FIG. 73  is a block diagram showing a specific configuration of the control block shown in  FIG. 71 . 
     The present fifth embodiment primarily differs from the above first embodiment in that, with an endoscope  2  provided with a bending portion  14  having a multi-joint link structure, insertability of an insertion portion  9  is enhanced by controlling driving of the bending portion  14  so that an angle of a distal end-side link member  21   a   1  of the bending portion  14  sequentially shifts along proximal end-side link members  21   a   1  to  21   an . Otherwise, descriptions on points similar to the first embodiment described above will be omitted. 
     A servo controller  36 A connected to a command control section  5 A according to the present fifth embodiment is arranged so that, when respectively controlling the rotational movement of each of the plurality of link members  21   a   1  to  21   an  that constitute the bending portion  14 , computational processing based on a dynamic control computing section, to be described later is performed. 
     More specifically, as shown in  FIG. 70 , a dynamic control computing section  336 B is provided at the servo controller  36 A. By performing signal processing (filtering) of a temporal/frequency domain based on a supplied operation command value signal (command value information), the dynamic control computing section  336 B creates an operation output value signal (driving signal) necessary for controlling the driving section  10   b  provided at the actuator control block  31 . 
     Next, a specific configuration and a shift control method of the servo controller  36 A for performing computational processing based on signal processing of the temporal/frequency domain will be described with reference to  FIGS. 71 to 73 . 
     As shown in  FIG. 71 , the servo controller  36 A includes a control block  341  (first to nth control blocks  41   a   1  to  41   an ). An operation command value signal including a servo command value signal at the distal end-side link member  21   a   1  is supplied to the control block  341 . 
     Based on the supplied command value signal and a position F/B signal, the control block  341  performs computational processing for obtaining an actuator control command signal that is a joint torque command value signal corresponding to a link member  21   a  by the dynamic control computing section  336 B, and outputs the signal to a corresponding driving section  10   b  and a subsequent-stage control block  341 . 
     First to nth actuator control command signals outputted from the control block  341  is arranged to be connected to command displacement information shown in  FIG. 72 . Based on the supplied command value signal and a position F/B signal that is displacement information of the motor  27  obtained from the sensor  38 , the PD control section  40  is used to perform PD control such as known proportional/differential control to create the actuator control command signal (driving signal), which is then supplied to the motor  27  to rotationally control the same. 
     In the present embodiment, the number of provided servo controllers  36 A corresponds to the number of the first to nth actuator control blocks  31   a   1  to  31   an . Therefore, the controller  5  includes a plurality of control blocks  341   a  to  341   an  whose number corresponds to the number of the first to nth actuator control blocks  31   a   1  to  31   an.    
     Accordingly, as shown in  FIG. 71 , the first control block  341   a  corresponding to the distal end-side link member  21   a   1  is connected to the command control section  5 A (refer to  FIG. 9 ). 
     A second control block  341   a   2  corresponding to the second-stage link member  21   a   2  and to which is inputted an output signal (first actuator control command signal) of the first control block  341   a   1  is connected to the first control block  341   a   1 . 
     A third control block  341   a   3  (not shown) corresponding to the third-stage link member  21   a   3  and to which is inputted an output signal (second actuator control command signal) of the second control block  341   a   2  is connected to the second control block  341   a   2 . 
     Henceforth, by performing connections in the same manner, an n−1st control block  341   a (n−1) corresponding to the n−1st-stage link member  21   a (n−1) is connected so as to acquire an output signal of a previous-stage control block  341 , and a nth control block  341   an  corresponding to the nth-stage link member  21   an  is connected so as to acquire an output signal of the previous-stage n−1st control block  341   a (n−1). 
     The operation command value signal is for instructing a joint angle (angle) formed by the distal end-side link member  21   a   1  and a link member  21   a   2  contiguous to the link member  21   a . Similarly, the first to nth actuator control command signals are for instructing joint angles (angles) formed by a corresponding link member  21   a  and a link member  21   a  consecutive thereto. 
     Through such a configuration, an operation command value signal (mainly of an angle) that drives the distal end-side link member  21   a   1  can be transmitted sequentially along a time series to link members  21   a  on the subsequent stage side. 
     Contents of the dynamic control computing section  336 B will be described below. 
       FIG. 73  shows a specific block configuration of the plurality of first to nth control blocks  341 . 
     As shown in  FIG. 73 , the control block  341  is configured to include a sample and hold circuit  342  and a storage element  343 . 
     The sample and hold circuit  342  samples the supplied operation command value signal, and holds the sampled operation command value signal for a presetting time before outputting the same to the storage element  343 . 
     The storage element  343  is storage section that temporarily stores the supplied operation command value signal, and when an operation command value signal is newly supplied, outputs the stored operation command value signal as an actuator control command signal. 
     Therefore, as described above, since the number of provided control blocks  341  constituted by the sample and hold circuit  342  and the storage element  343  correspond to the number of the first to nth actuator control blocks  31   a   1  to  31   an , a plurality of first to nth sample and hold circuits  342   a   1  to  342   an  is connected to a plurality of storage elements  343   a   1  to  343   an  as shown in  FIG. 73 . 
     In other words, an operation command value signal of the distal end-side link member  21   a   1  is first sampled by the first sample and hold circuit  341   a   1 , whereby the sampled operation command value signal is held for a presetting time and outputted to the storage element  343   a   1 . 
     When the operation command value signal is supplied to the storage element  343   a   1 , the operation command value signal is temporarily stored in the storage element  343   a   1 . An operation command value signal already stored is supplied as a first actuator control command value signal to the motor  27  corresponding to the distal end-side link member  21   a   1  of the driving section  10   b  and to the second sample and hold circuit  342   a   2  of the second-stage that is the subsequent stage. 
     Consequently, rotational control of the motor  27  based on the first actuator control command value signal causes the distal end-side link member  21   a   1  to rotationally move by an angle based on the operation command value signal. 
     Then, the first actuator control command value signal is sampled by the second sample and hold circuit  342   a   2 , whereby the sampled operation command value signal is held for a presetting time and outputted to the storage element  343   a   2 . 
     When the operation command value signal is supplied to the storage element  343   a   2 , the operation command value signal is temporarily stored in the storage element  343   a   2 . An operation command value signal already stored is supplied as a second actuator control command value signal to the motor  27  corresponding to the second-stage link member  21   a   2  of the driving section  10   b  and to the third sample and hold circuit  342   a   3  (not shown) of the third-stage (not shown) that is the subsequent stage. 
     Consequently, rotational control of the motor  27  based on the second actuator control command value signal causes the second-stage link member  21   a   2  to rotationally move after the lapse of the time preset by the second sample and hold circuit  342   a   2  by an angle based on the operation command value signal or, in other words, the same angle as the distal end-side link member  21   a   1 . 
     In this manner, an actuator control command signal of the previous stage is similarly sampled by the third-stage link member  21   a   2 , . . . , the n−1st-stage link member  21   a (n−1), and the nth t-stage link member  21   an , whereby, after a lapse of a presetting time, the actuator control command signal is supplied to a corresponding motor  27  via the storage element  343 . As a result, the respective link members  21   a  rotationally move in sequence by the same angle as the distal end-side link member  21   a   1  at each presetting time along a time series. 
     In other words, the bending portion  14  performs a bending movement such that the angle of the distal end-side link member  21   a   1  sequentially shifts along the plurality of proximal end-side link members  21   a   2  to  21   an  consecutive thereto in a time series for each sample and hold time (presetting time). 
     With the endoscope apparatus  1  as described above, when inserting the insertion portion  9  into the large intestine, the operator inserts the insertion portion  9  via the anus. Then, when the distal end portion  13  of the insertion portion  9  reaches the sigmoid colon segment, the servo controller  36 A performs bending movement of the distal end-side link member  21  also that a spatial direction (angle) designated by the operation command section  7  is assumed. 
     Consequently, since the distal end-side link member  21   a   1  is bent by the designated angle, further insertion along the intestinal wall of the sigmoid colon segment is enabled. 
     After the lapse of a preset setting time (hold time), the second-stage link member  21   a   2  contiguous to the distal end-side link member  21   a   1  performs a bending movement in the same direction (angle) as the distal end-side link member  21   a   1 . 
     Henceforth, the third-stage link member  21   a   3  and the plurality of link members subsequent thereto similarly perform bending movement so as to sequentially shift in the same direction (angle) as the distal end-side link member along a time series at each setting time. 
     Accordingly, the bending portion  14  will be inserted while performing bending movements such that, in association to an insertion operation, the angle of the distal end-side link member  21   a   1  sequentially shifts from the distal end-side to the proximal end-side so as to conform to the shape of the sigmoid colon segment. 
     Consequently, it is now possible to pass through the sigmoid colon segment, which conventionally presented difficulties for insertion, in an easy manner. Therefore, since insertions into deep portions of the large intestine can be more readily performed, insertability can be improved. 
     In the endoscope apparatus  1  according to the fifth embodiment, the plurality of link members  21   a  constituting the bending portion  14  performs bending movements so that the angle of the distal end-side link member  21   a   1  sequentially shifts at each setting time towards the proximal end-side link members  21   a  to  21   an . However, instead of using the angle of the distal end-side link member  21   a   1 , it also is possible to designate an arbitrary link member  21   a  (also referred to as an object axis) whose angle is to be shifted. The setting time (hold time) can also be set arbitrarily. Such a first variation of the fifth embodiment is shown in  FIG. 74 . 
       FIG. 74  is a block diagram showing the first variation of the fifth embodiment. 
     As shown in  FIG. 74 , a controller  5  according to the first variation is provided with: a shaft selecting section  344  as selecting section; a hold time setting section  345  as time changing section; an offset quantity selecting section  346 ; and a setting section  347 . 
     The shaft selecting section  344  designates a shaft or, in other words, an arbitrary link member  21   a  whose angle is to be subjected to shift control and outputs a designation signal to the setting section  347 . In other words, by providing the shaft selecting section  344 , a shaft whose angle is to be shifted is no longer limited to that of the distal end-side link member  21   a   1 , and the angle of another arbitrary shaft (link member  21   a ) can be shifted. 
     The hold time setting section  345  is capable of arbitrarily setting sample and hold times (setting times) of the first to nth sample and hold circuits  342   a   1  to  342   an , and outputs a setting time that has been set to the setting section  347 . In other words, by providing the hold time setting section  345 , it is now possible to freely set a movement travel time among the respective link members  21   a  in which shifting is sequentially performed in a time series from the distal end-side to the proximal end-side. 
     For example, when performing insertion while shift control of the bending portion  14  of the insertion portion  9  is performed in a slow manner, the hold time (setting time) may be set long by the hold time setting section  345 . Conversely, when performing insertion while shift control of the bending portion  14  of the insertion portion  9  is performed in a speedy manner, the hold time (setting time) may be set short by the hold time setting section  345 . 
     The offset quantity selecting section  346  selects a quantity in which the direction of the link member  21   a  selected by the shaft selecting section  344  or the link member  21   a  that is preset by the operation command section  7  is to be changed, and outputs an offset command value signal to the setting section  347 . In other words, by providing the offset quantity selecting section  346 , when changing the direction of the designated link member  21   a , it is now possible to perform adjustment by subtly changing (offsetting) the direction of the designated link member  21   a  by only the quantity based on the offset command value signal. 
     Consequently, a designation signal from the shaft selecting section  344 , a setting signal from the hold time setting section  345  and an offset command value signal from the offset quantity selecting section  346  are supplied to the setting section  347  which then performs setting based on the control signals. 
     In other words, when a designation signal is supplied from the shaft selecting section  344 , the setting section  347  sets a link member  21   a  based on the designation signal as a link member  21   a  from which shift control is to be started. When a setting signal is supplied from the hold time setting section  345 , the setting section  347  sets a hold time of a relevant sample and hold circuit  342  so as to match a hold time based on the setting section. Further, when an offset command value signal is supplied from the offset quantity selecting section  346 , the setting section  347  performs setting so that the direction of the designated link member is changed by only the quantity based on the offset command value signal. 
     Consequently, according to the first variation, in addition to achieving the same advantageous effects as the fifth embodiment, it is now possible to arbitrarily set a movement time of the respective link members  21   a  in which the angle of the distal end-side link member  21   a   1  is sequentially shift-controlled towards proximal end-side link members  21   a   2  to  21   an . It is also possible to arbitrarily set a link member  21   a  from which shift control is to be started, and to arbitrarily set an offset quantity of the designated link member  21   a . Consequently, it is now possible to perform optimum shift control in accordance with an insertion state, thereby further enhancing insertability. 
     When inserting the bending portion  14  of the insertion portion  9  into a tube cavity such as the large intestine while performing shift control of the bending portion  14 , insertability can be further enhanced by taking the insertion quantity or, in other words, the operation quantity of the insertion portion  9  into consideration. Such a second variation of the fifth embodiment is shown in  FIG. 75 . 
       FIG. 75  is a block diagram showing the second variation of the fifth embodiment. 
     As shown in  FIG. 75 , an operation quantity change detecting section  50  is provided at the controller  5  according to the second variation. 
     The operation quantity change detecting section  350  receives an operation command value signal with respect to the distal end-side link member  21   a   1  as an input from the command control section  5 A, detects an operation quantity of the distal end-side link member  21   a   1  from the operation command value signal, and outputs a detection result as a data updating signal for updating data of the sample and hold circuit  342  to the first to nth sample and hold circuits  342   a   1  to  342   an.    
     When the data updating signal is supplied, the first to nth sample and hold circuits  342   a   1  to  342   an  simultaneously update their respective data. Therefore, when the operation quantity of the distal end-side link member  21   a   1  changes, the first to nth sample and hold circuits  342   a   1  to  342   an  update data at a speed in accordance to the operation quantity. In other words, the present second variation is arranged so that, when the operation quantity of the distal end-side link member  21   a   1  changes, shift control is sequentially performed on the plurality of link members  21   a  contiguous to the distal end-side link member  21   a   1  in accordance to the variation in operation quantity. 
     Consequently, since there is no temporal dependency and since shift control can be performed in accordance to the variation in operation quantity of the distal end-side link member  21   a   1 , the insertability of the insertion portion  9  can be enhanced. 
     With the second variation, in order to prevent unintentional shift control of the bending portion  14  due to a hypersensitive detection of a variation in operation quantity by the operation quantity change detecting section  350 , means such as those shown in  FIG. 76  or  77  may be provided. 
       FIG. 76  is a block diagram showing a specific configuration of the operation quantity change detecting section shown in  FIG. 75 , while  FIG. 77  is a block diagram showing a configuration in which a blind bandwidth setting section is provided at the operation quantity change detecting section shown in  FIG. 75 . 
     As shown in  FIG. 76 , the operation quantity change detecting section  350  includes: a variation calculating section  351  that calculates an operation variation of the distal end-side link member  21   a   1  from an operation command value signal; and a detecting range section  352  that outputs a data updating signal by performing detection from a calculation result of the variation calculating section  351  at a preset detecting level. The detecting range section  352  is capable of arbitrarily setting a detecting level. 
     Such a configuration enables a detecting level of an operation variation of the distal end-side link member  21   a   1  by the detecting range section  352  to be arbitrarily set. Therefore, it is now possible to prevent shift control from being intentionally performed on the bending portion  14 , thereby enhancing safety. 
     In addition, with the second variation, as shown in  FIG. 77 , a dead bandwidth setting section  353  capable of arbitrarily setting a dead bandwidth of a detecting range of the detecting range section  352  shown in  FIG. 76  may be provided. 
     For example, when it is desirable to narrow down the dead bandwidth of a detecting range of the detecting range section  352 , the operator operates the dead bandwidth setting section  353  to perform setting so that the dead bandwidth is narrowed down as is the case of the detecting range section  352  indicated in the direction of the arrow shown in the diagram. Obviously, it is also possible to conversely widen the dead bandwidth of the detecting range section  352 . 
     Consequently, detection of an operation variation of the distal end-side link member  21   a   1  can now be performed over a wide range, thereby contributing towards the improvement of safety. 
     While a configuration in which the operation quantity change detecting section  350  is provided in the servo controller  36 A has been described, the present invention is not limited to this arrangement, and the operation quantity change detecting section  350  may instead be provided in the operation command section  7 . 
     Next,  FIGS. 78 to 83  are related to a sixth embodiment.  FIG. 78  is a block diagram showing an overall configuration of a servo controller provided at each actuator control block.  FIG. 79  is a graph showing characteristics of gain and frequency of an input/output signal of the control block shown in  FIG. 78 .  FIG. 80  is a graph showing characteristics of phase and frequency of an input/output signal of the control block shown in  FIG. 78 .  FIGS. 81 and 82  are explanatory diagrams for obtaining the frequency characteristics shown in  FIGS. 79 and 80 , wherein:  FIG. 81  is a diagram showing a state in which an extremum and a zero point on a real axis of a complex open plane are set to be symmetrical with respect to an imaginary axis; and  FIG. 82  is a diagram showing a state in which positive and negative extrema and zero points on a real axis of a complex open plane are set to be symmetrical with respect to an imaginary axis.  FIG. 83  is a block diagram showing a filter section included in the first control block shown in  FIG. 78 . 
     With the present embodiment, when performing shift control of the bending portion  14  from the distal end-side link members  21   a  to the proximal end-side link members  21   a , instead of management by time, it is possible to control shift operations to be performed faster or slower depending on the frequency of the operation command value signal. In other words, a phase in a frequency range of the operation command value signal sequentially transmitted from the distal end-side to the proximal end-side is realized through shifting. 
     As shown in  FIG. 78 , a controller  5  according to the present embodiment includes a command control section  5 A and first to nth actuator control blocks  31   a   1  to  31   an  in the same manner as in the fifth embodiment. In the same manner as the connection mode shown in  FIG. 71 , a plurality of first to nth control blocks  441 A 1  to  441 An (hereinafter also collectively referred to as control block  441 ) are provided at the first to nth actuator control blocks  31   a   1  to  31   an.    
     The first to nth control blocks  441 A 1  to  441 An respectively include a filter section  454  (refer to  FIG. 83 ) for shifting the phase of an inputted actuator control command signal. 
     The filter section  454  has filter characteristics in that gain of input/output signals is constant and output is provided having a preset phase lag. More specifically, as shown in  FIG. 83 , by performing computational processing using a rational function (S−P/S+P, where S represents a Laplace operator and P represents an extremum (zero point)) of a complex open plane on an input signal, the filter section  454  obtains an output signal whose gain is constant and which has a preset phase lag. 
     In other words, as shown in  FIG. 79 , a gain G of an input/output signal of each control block  441  is not dependent on a frequency f of the signal and is uniform. When each input/output signal has a phase lag, the phase lag P 0  of the input/output signals is, as shown in  FIG. 80 , not dependent on a frequency f of the signal and is uniform. 
     Therefore, as shown in  FIG. 81 , by setting an extremum ◯ and a zero point X on the real axis (real) to be symmetrical with respect to the imaginary axis (imag) on a complex open plane, or, as shown in  FIG. 82 , by setting an extremum ◯ and a zero point X on positive/negative (+−) real axes (real) to be symmetrical with respect to the imaginary axis (imag) on a complex open plane, frequency characteristics such as those shown in  FIGS. 79 and 80  may be obtained. 
     Therefore, by using such frequency characteristics, the filter section  454  will acquire filter characteristics in that gain of input/output signals is constant and output is provided having a preset phase lag. 
     Consequently, with the controller  5  shown in  FIG. 78 , by using a phase lag of an input/output signal from the filter section  454  of each of the first to nth control blocks  441 A 1  to  441 An instead of using a sample and hold time used in the fifth embodiment, shift control of a plurality of link members  21   a  can be performed in the same manner as in the fifth embodiment. 
     As illustrated by the first variation shown in  FIG. 84 , the sixth embodiment may be configured so that an extremum/zero point setting section  455  is provided as a phase changing section capable of adjusting and setting a phase lag quantity of an input/output signal from the filter section  454  of each of the first to nth control blocks  441 A 1  to  441 An. 
     In this case, as shown in  FIGS. 81 and 82 , the extremum/zero point setting section  455  varies the phase lag quantity of output signals of the first to nth control blocks  441 A 1  to  441 An by changing and setting an extremum and a zero point that determine filter characteristics of the filter section  454 . 
     Consequently, when performing shift control of the bending portion  14  from the distal end-side towards the proximal end-side link members  21   a  using the phase lag, it is possible to perform control so as to extend or delay the shift travel time by varying the phase lag quantity. 
     With the endoscope apparatus  1  according to the sixth embodiment, while the plurality of link members  21   a  constituting the bending portion  14  performs bending movements so that an angle of the distal end-side link member  21   a   1  sequentially shifts to the proximal end-side link members  21   a   2  to  21   an  each preset phase lag quantity, the phase lag quantity can be changed arbitrarily. In addition, an arbitrary link member  21   a  (also referred to as an object axis) that changes the phase lag quantity can also be designated. Such a second variation of the sixth embodiment is shown in  FIG. 85 . 
       FIG. 85  is a block diagram showing the second variation of the sixth embodiment. 
     As shown in  FIG. 85 , a controller  5  according to the sixth variation is provided with a shaft selecting section  444 A, an offset selecting section  456 , and an extremum/zero point selecting section  455 A. 
     The shaft selecting section  444 A designates a shaft or, in other words, an arbitrary link member  21   a  whose phase lag quantity is to be changed, and outputs a designation signal to a setting section  447 A. In other words, providing the shaft selecting section  444 A enables selection of an arbitrary shaft (link member  21   a ) whose phase lag quantity is to be changed. 
     The offset selecting section  456  selects a quantity in which the direction of the link member  21   a  selected by the shaft selecting section  444 A or the link member  21   a  that is preset by the operation command section  7  is to be changed, and outputs an offset command value signal to the setting section  447 A. In other words, by providing the offset selecting section  456 , when changing the direction of the designated link member  21   a , it is now possible to perform adjustment by subtly changing (offsetting) the direction of the designated link member  21   a  by only the quantity based on the offset command value signal. 
     The extremum/zero point selecting section  455 A is capable of arbitrarily setting a phase lag quantity of output signals of the first to nth control blocks  441 A 1  to  441 An by changing and setting an extremum and a zero point that determine filter characteristics of the filter section  454 , and outputs a set setting signal to the setting section  447 A. In other words, by providing the extremum/zero point selecting section  455 A, it is now possible to freely set a movement travel time among the respective link members  21   a  in which shifting is performed based on the phase lag of the input/output signal from the distal end-side to the proximal end-side. 
     For example, when performing insertion while shift control of the bending portion  14  of the insertion portion  9  is performed in a slow manner, the phase lag quantity from the filter section  454  should be set to increase by the extremum/zero point selecting section  455 A. Conversely, when performing insertion while shift control of the bending portion  14  of the insertion portion  9  is performed in a speedy manner, the phase lag quantity from the filter section  454  should be set to decrease. Such settings may be made on a filter section  454  corresponding to a link member  21   a  selected by the shaft selecting section  444 A. This enables shift control to be performed over a wide range. 
     Consequently, a designation signal from the shaft selecting section  444 A, an offset command value signal from the offset selecting section  456  and a setting signal from the extremum/zero point selecting section  455 A is supplied to the setting section  447 A which then performs setting based on the control signals. 
     In other words, when a designation signal is supplied from the shaft selecting section  444 A, the setting section  447 A sets a link member  21   a  based on the designation signal as a link member  21   a  whose phase lag quantity is to be changed. Further, when an offset command value signal is supplied from the offset selecting section  456 , the setting section  447 A performs setting so that the direction of the designated link member  21   a  is changed by only the quantity based on the offset command value signal. When a setting signal from the extremum/zero point selecting section  455 A is supplied, a phase lag quantity of a relevant filter section  454  is set so as to match a phase lag quantity based on the setting signal. 
     Consequently, according to the second variation, in addition to achieving the same advantageous effects as the sixth embodiment, it is now possible to arbitrarily set a time of movement due to a phase lag quantity of the respective link members  21   a  in which the angle of the distal end-side link member  21   a   1  is sequentially shift-controlled towards proximal end-side link members  21   a   2  to  21   an . It is also possible to arbitrarily set a phase lag quantity and to arbitrarily set an offset quantity of the designated link member  21   a . Consequently, it is now possible to perform optimum shift control in accordance with an insertion state, and insertability can be further enhanced. 
     In the second embodiment 2, in addition to designating a link member  21   a  whose phase lag quantity is to be changed, the shaft selecting section  444 A may be arranged to also designate a link member  21   a  (also referred to as an object axis) from which shifting of an angle is commenced using a phase lag quantity. 
       FIG. 86  is a block diagram showing an overall configuration of a servo controller provided at each actuator control block, according to a seventh embodiment of the present invention.  FIGS. 87 to 91  present a variation of the seventh embodiment, wherein:  FIG. 87  is a block diagram showing an overall configuration of a servo controller provided with setting section for setting a shift pathway;  FIG. 88  is an explanatory diagram for explaining channels settable by a channel setting section shown in  FIG. 87 ;  FIG. 89  is a diagram showing an example of an input/output signal of the channel setting section;  FIG. 90  is a diagram showing a replacement matrix used during channel setting by the channel setting section; and  FIG. 91  is a diagram showing an example of a channel setting set by the channel setting section. 
     An endoscope apparatus  1  according to the seventh embodiment is a modification of the endoscope apparatus according to the fifth embodiment and is capable of designating a link member  21   a  from which shift control is to be commenced, and is configured so that an arbitrary link member  21   a  that shifts the angle of the designated link member  21   a  is selectable. 
     As shown in  FIG. 86 , the overall configuration of the servo controller  36 A according to the present embodiment is approximately the same as the block configuration shown in  FIG. 71 , with the exception of the servo controller  36 A according to the present embodiment being provided with a shaft selection setting section  457  and a plurality of switches Sa 1  to San and S 1   a   1  to S 1   an  provided at each sample and hold circuit  342  ( 342   a   1  to  342   an ). 
     More specifically, an operation command value signal inputted to the first sample and hold circuit  342   a   1  is supplied to the subsequent-stage second sample and hold circuit  342   a   2  and the switch Sa 2  via the switch Sa 1 . 
     The switch S 1   a   1  is provided on the output side of a storage element  343   a   1 , and when the switch S 1   a   1  is switched on, an output signal from the first sample and hold circuit  342   a   1  is outputted as a first actuator control command signal via the storage element  343   a   1 . 
     An operation command value signal inputted to the second sample and hold circuit  342   a   2  is supplied to the subsequent-stage third sample and hold circuit  342   a   3  (not shown) and the switch Sa 3  (not shown) via the switch Sa 2 . 
     The switch S 1   a   2  is provided on the output side of a storage element  343   a   2 , and when the switch S 1   a   2  is switched on, an output signal from the second sample and hold circuit  342   a   2  is outputted as a second actuator control command signal via the storage element  343   a   2 . 
     Henceforth, a switch San is connected in a similar manner to a sample and hold circuit  342   an  corresponding to a subsequent-stage link member  21   a , and a similar switch S 1   an  is also connected to the output side of a storage element  343   an  of the sample and hold circuit  342   an.    
     The switch Sa 1  and the switch S 1   a   1  correspond to the distal end-side link member  21   a   1 ; the switch Sa 2  and the switch S 1   a   2  correspond to the subsequent-stage second link member  21   a   2 ; and subsequently, in the same manner, the switch San and the switch S 1   an  are provided so as to correspond to the nth-stage link member  21   an.    
     The shaft selection setting section  4457  sets a link member  21   a  at which shift control is to be commenced, and is also capable of setting an arbitrary link member  21   a  that shifts the angle of the set link member  21   a . The shaft selection setting section  457  is also arranged to control switching of the switches Sa 1  to San and switches S 1   a   1  to S 1   an  based on the set setting contents. 
     In this case, the shaft selection setting section  457  performs control so that the switch  5   a  corresponding to the set link member  21   a  is switched off and the switch S 1   a  provided on the side of the storage element  343  corresponding to the set link member  21   a  is switched on. 
     Conversely, the shaft selection setting section  457  performs control so that a switch Sa corresponding to a link member  21   a  that has not been set is switched on and operation command value information is transmitted to a subsequent stage, and at the same time, a switch S 1   a  provided on the side of the storage element  343  corresponding to the set link member  21   a  is switched off to suspend output of an actuator control command signal. 
     According to such a configuration, for example, by designating the second link member  21   a   2  as the link member  21   a  at which shift control is to be commenced and setting the fourth to nth link members  21   a   4  to  21   an  as the link member  21   a  that shifts the angle of the link member  21   a   2 , the shaft selection setting section  457  can perform control so that the angle of the second link member  21   a   2  shifts along the fourth to nth link members  21   a   4  to  21   an . Consequently, the insertability of the insertion portion  9  can be even more enhanced than that with the fifth embodiment. 
     As illustrated by the variation shown in  FIG. 87 , the seventh embodiment may be configured so that a channel setting section  460  to be connected to a network setting section  461  is provided at the output side of a storage element  343  corresponding to each link member  21   a , and an order in which shift control is to be performed is changed by the channel setting section  460  based on a setting signal set by the network setting section  461 . 
     In this case, the channel setting section  460  changes an output pathway (also referred to as a channel) of an output signal of each storage element  343   a   1  to  343   an  based on a setting signal set by the network setting section  461  or, in other words, a setting signal indicating an order in which shift control is to be performed. 
     For example, as shown in  FIG. 88 , assuming that input  1  is an output signal of the first sample and hold circuit  342   a   1 , the channel setting section  460  is capable of arranging input  1  to be outputted by any of output  1  that is a first actuator control command signal, output  2  that is a second actuator control command signal, and output  3  that is a third actuator control command signal. In the same manner, the channel setting section  460  is capable of arranging input  2  to be outputted by any of output  1  that is the first actuator control command signal, output  2  that is the second actuator control command signal, and output  3  that is the third actuator control command signal. Henceforth, in a similar manner, input  3 , . . . , input n can also be outputted via any of the output pathways (channels). 
     In other words, with the channel setting section  460 , in the case where software for changing an output pathway is used, the channel can be changed by using a replacement matrix as shown in  FIG. 90  based on a setting signal from the network setting section  461 . 
     By using matrix computation on a replacement matrix, channel switching is now possible without having to perform special processing. 
     In the case of the replacement matrix shown in  FIG. 90 , channels of input/output signals such as those shown in  FIG. 89  are realized.  FIG. 91  shows an example of a channel setting set by the channel setting section  460 . 
     As shown, by performing a computation that combines replacement matrices, arbitrary channel setting becomes possible. 
     Consequently, according to the present variation, by providing the network setting section  461  and the channel setting section  460 , output pathways (channels) of input/output signals can be set arbitrarily. As a result, an order in which shifting is to be performed can now be changed in a simple and easy manner. 
       FIGS. 92 to 94  relate to an eighth embodiment of the present invention, wherein:  FIG. 92  is an explanatory diagram for explaining basic shifting control;  FIG. 93  is an explanatory diagram for explaining shifting control based on relative displacement according to the eighth embodiment; and  FIG. 94  is a block diagram showing an overall configuration of a servo controller provided at each actuator control block according to the eighth embodiment.  FIG. 95  is a block diagram showing a specific configuration of the relative displacement converting section shown in  FIG. 94 .  FIG. 96  represents a first variation of the eighth embodiment, and is an explanatory diagram for explaining another shifting control based on relative displacement; and  FIG. 97  represents a second variation of the eighth embodiment and is a block diagram showing an overall configuration of a controller  5  and peripheral devices of the controller  5 . 
     The endoscope apparatus  1  according to the present invention is arranged so that an angle of a designated link member  21   a  is sequentially shift-controlled along subsequent stage-side link members  21   a . Let us now assume that, for example, the angle of the distal end-side link member  21   a   1  is 45 degrees and that the angle of 45 degrees is sequentially shift-controlled along subsequent stage-side link members  21   a   2  to  21   a   7 . Since the angle of 45 degrees that is to be shifted is an absolute travel distance, in the event that the angle of 45 degrees reaches the most proximal end-side link member  21   a   7 , the attitude of the bending portion  14  will change in a procedure such as that shown in  FIG. 92 . In other words, simply performing shift control causes the bending portion  14  to perform bending movements which result in assuming the attitude such as that shown in  FIG. 92 . As a result, when performing operation, the links assume a coiled shape that is quite possibly an attitude that may inflict a burden on the patient inside a body cavity. 
     Therefore, for the purpose of further enhancing the insertability of the insertion portion  9  while considering the bending attitude of the bending portion  14 , in addition to the absolute travel distance described earlier, the present embodiment also enables angles of the respective link members  21   a  to be controlled based on relative travel distances obtained based on angular displacements of link members  21   a  along which an angle is to be shifted. 
     More specifically, as shown in  FIG. 94 , the overall configuration of a servo controller  36 A according to the present embodiment is approximately similar to the block configuration shown in  FIG. 71  according to the fifth embodiment with the exception of the servo controller  36 A according to the present embodiment being provided with a shaft selecting section  444 B and a plurality of relative travel distance converting sections  462   a   1  to  462   an  respectively provided on the output side of a plurality of storage elements  343   a   1  to  343   an  corresponding to the plurality of link members  21   a.    
     The shaft selecting section  444 B is capable of respectively controlling the on/off states of the plurality of relative travel distance converting sections  462   a   1  to  462   an . The shaft selecting section  444 B is also capable of designating a link member  21   a  that performs shift control based on an absolute travel distance (hereinafter referred to as the absolute travel distance shift mode) similar to the fifth embodiment and which is shown in  FIG. 92 , and a ink member  21   a  that performs shift control based on an relative travel distance, to be described later (hereinafter referred to as the relative travel distance shift mode). 
     In other words, as for a link member  21   a  designated so as to execute the absolute travel distance shift mode, the shaft selecting section  444 B switches off a relative travel distance converting section  462  on a corresponding output pathway, and causes an output signal from a storage element  463  to be outputted without modification as an actuator control command signal. On the other hand, as for a link member  21   a  designated so as to execute the relative travel distance shift mode, the shaft selecting section  444 B switches on a relative travel distance converting section  462  on a corresponding output pathway, applies relative travel distance conversion processing on an output signal from a storage element  343 , and causes the same to be outputted as an actuator control command signal. 
     The on/off state of the relative travel distance converting section  462  is controlled by the shaft selecting section  444 B, and the relative travel distance converting section  462  is, for example, a differential circuit that applies relative travel distance conversion processing on an actuator control signal that is an input signal. 
     A specific configuration of the relative travel distance converting section  462  (relative travel distance converting sections  462   a   1  to  462   an ) is shown in  FIG. 94 . 
     As shown in  FIG. 94 , the relative travel distance converting section  462  includes: a relative travel distance converting circuit  463  that acquires a command value signal from a storage element  343  and calculates an angular relative travel distance (relative displacement) with respect to the command value signal; a relative travel distance storing section  464  that temporarily stores and outputs an output signal of the relative travel distance converting circuit  463 ; a converting section  465  that converts the relative travel distance from the relative travel distance storing section  464  into the opposite direction; and a sample and hold circuit  466  that samples the output signal of the converting section  465  over a set sampling time and feeds back the same to the relative travel distance converting circuit  463 . 
     In other words, switching on the relative travel distance converting section  462  causes a corresponding link member  21   a  to be controlled so as to first rotationally move by an angle based on an operation command value signal, and then rotationally move by an angle that is the traveled relative travel distance (relative displacement) so as to return to its original angle. 
     For example, assuming that the relative travel distance shift mode has been designated for all link members  21   a  by the shaft selecting section  444 B, the relative travel distance converting sections  462   a   1  to  462   an  shown in  FIG. 94  are switched on. As a result, at the bending portion  14 , as shown in  FIG. 93 , the distal end-side link member  21   a   1  first rotationally moves by an angle based on an operation command value signal as described above and then returns to its original angle. Subsequently, at the same time the angle is transmitted to the second-stage side, the second-stage link member  21   a   2  moves in a similar manner. Henceforth, subsequent-stage link members  21   a   3  to  21   a   7  sequentially move in a similar manner. In other words, the bending portion  14  performs bending movements as though the angle of the distal end-side link member  21   a   1  migrates without modification towards the proximal end-side. 
     Therefore, according to the present embodiment, appropriately designating a link member  21   a  that executes the absolute travel distance shift mode and a link member  21   a  that executes the above-mentioned relative travel distance shift mode by the shaft selecting section  444 B enables bending movements more suited an object member can be performed. As a result, the insertability of the insertion portion  9  can be further enhanced. 
     With the present embodiment, by modifying the relative travel distance converting section  462 , as illustrated by the first variation shown in  FIG. 96 , it is also possible to have the bending portion  14  perform bending movements (locomotion movement) as though a link member  21   a  that has rotationally moved by an angle based on an operation command value signal sequentially performs parallel translation towards the proximal end-side. 
     In addition, the present embodiment may be configured so that, as means for instructing the execution of a bending movement pattern of the bending portion  14 , instead of operation by the operation command section  7  such as a joystick, as illustrated by the second variation shown in  FIG. 97 , “automatic control by a preset operation pattern” may be performed by providing an inputting section  470  and a pattern command value creating section  471 . 
     In other words, as shown in  FIG. 97 , an endoscope apparatus  1  according to the second variation is further provided with: the inputting section  470  that is an inputting I/F that selects what bending movement waveform will be employed when performing shift control of a designated angle; the pattern command value creating section  471  that creates a pattern signal based on the bending movement waveform selected by the inputting section  470  and outputs the same to the CPU  32  shown in  FIG. 10 ; and a communication I/F  472  connected to the CPU  32  and which is capable of communicating with other operation devices in a hospital or with a communication device for performing a remote operation from outside of the hospital. 
     For example, when sinusoidal wave is selected by the inputting section  470 , the bending portion  14  will perform bending movements such that the designated angle sequentially shifts as though a sinusoidal wave. When triangular wave is selected by the inputting section  470 , the bending portion  14  will perform bending movements such that the designated angle sequentially shifts as though tracing the respective sides of a triangle. When rectangular wave is selected by the inputting section  470 , the bending portion  14  will perform bending movements such that the designated angle sequentially shifts as though a rectangular wave. An arbitrary waveform other than those described above may be inputted at the inputting section  470 . 
     Consequently, by selecting and setting in advance a bending movement waveform for creating an optimum bending movement pattern in accordance with a procedure, the operator will be able to automatically perform shift control of the bending portion  14  in an optimum bending movement pattern in accordance with a procedure without operating the operation command section  7  such as a joystick. As a result, the insertability of the insertion portion  9  can be further enhanced. 
     For the embodiments according to the present invention, while the bending portion  14  having the insertion portion driving mechanism constituting a manipulator has been described as being provided at the insertion portion  9  of the endoscope  2 , the bending portion  14  may be arranged to be provided at an insertion portion of an endoscope insertion aiding device that aids the insertion of the insertion portion  9  into a tube cavity by allowing insertion of the insertion portion  9  of the endoscope  2 . 
     As seen, for the present embodiment, while descriptions on planar movements has been given for simplicity, in an endoscope, it is obvious that the descriptions shall translate to configurations for performing movements in three-dimensional space. 
     The present invention is not limited to the respective embodiments and variation thereof described above, and various modifications can be made without departing from the gist of the present invention. It is needless to say that the respective embodiments and variation thereof described above may be combined as appropriate.