Slack correction mechanism, manipulator, and manipulator system

The slack correction mechanism includes a distal-end pulley that is rotatable with respect to a given axis, a distal-end wire wound around the distal-end pulley, a first supporting part including a first base, a first friction portion around which the distal-end wire is looped on one side and a first biasing portion that biases the distal-end wire in a pulling direction on one end side with respect to the first friction portion, the first supporting part being adapted to support one side of the distal-end wire, and a second supporting part including a second base, a second friction portion around which the distal-end wire is looped on the other side and a second biasing portion that biases the distal-end wire in a pulling direction on the other side with respect to the second friction portion, the second supporting part being adapted to support the other side of the distal-end wire.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a slack correction mechanism used with an apparatus in which a distal end member mounted on a pulley is put in operation by pulling or letting out a wire wound around the pulley for the purpose of correcting slack in the wire as well as a manipulator and a manipulator system.

FIGS. 16A, 16B and 16Cis a schematic view of one example of one typical prior art manipulator.

So far there has been a manipulator used in which a wire130is wound on one side around a driving pulley140and on the other side around a driven pulley120for power transmission, as shown inFIG. 16A.

When the driving pulley140is rotated by an operator (not shown) from a neutral state ofFIG. 16Ain a direction indicated by an action arrow A1, the wire130tends to move in a direction indicated by an action arrow B in association with the rotation of the driving pulley140in the direction indicated by the action arrow A1. Because the necessary load is applied to the driven pulley120when it starts to rotate, however, the driven pulley120does not rotate even upon rotation of the driving pulley140. For this reason, there is an elongation131of the wire130pulled by the driving pulley140, and there is slack132in the wire130let out by the driving pulley140, as shown inFIG. 16B.

When the driving pulley140is then reversed in a direction indicated by an action arrow A2as shown typically inFIG. 16C, the pulling force is not transmitted to the driven pulley120until the dynamic slack132in the wire130, shown inFIG. 16B, is removed, with the result that a distal-end member121attached to the driven pulley120is unlikely to go into operation even with the operation of the driving pulley140, as shown inFIG. 16C.

Japanese Patent No. 4145464 discloses the technology of pulling the slack in the wire by means of a spring for removal of such slack132as shown inFIG. 16Bthereby reducing operational delay shown inFIG. 16C.

SUMMARY OF INVENTION

According to one embodiment, a slack correction mechanism includes

a distal-end pulley that is rotatable with respect to a given axis,

a wire wound around the distal-end pulley,

a first supporting part including a first base, a first friction portion which extends out from the first base and around which the wire wound around the distal-end pulley is looped on one side and a first biasing portion that biases the wire in a pulling direction on one end side with respect to the first friction portion, the first supporting part being adapted to support one side of the wire, and

a second supporting part including a second base, a second friction portion which extends out from the second base and around which the wire wound around the distal-end pulley is looped on the other side and a second biasing portion that biases the wire in a pulling direction on the other side with respect to the second friction portion, the second supporting part being adapted to support the other side of the wire.

According to one embodiment, a manipulator includes

a distal-end part that takes rotatable hold of the distal-end pulley by pulling or letting out the distal-end wire, and

the slack correction mechanism.

According to one embodiment, a manipulator system includes

the manipulator,

a control unit for controlling the manipulator, and

a display unit for displaying an image acquired through the manipulator, wherein:

the manipulator includes an endoscope having a viewing optical system, an imaging device and a lighting optical system, and

the control unit permits an image acquired through the endoscope to be displayed on the display unit.

DESCRIPTION OF EMBODIMENTS

Some embodiments are now explained.

FIG. 1is a schematic view of one example of the slack correction mechanism1according to the first embodiment.

The slack correction mechanism1according to the first embodiment includes a distal-end pulley2that is rotatable with respect to a given axis2a, a distal-end wire3wound around the distal-end pulley2, a first supporting part4including a first base41, a first friction portion42which extends out from the first base41and around which the distal-end wire3wound around the distal-end pulley2is looped on one side and a first coil spring43defining a first biasing portion which biases the distal-end wire3in a pulling direction on one end side with respect to the first friction portion42, the first supporting part4being adapted to support one side of the distal-end wire3, and a second supporting part5including a second base51, a second friction portion52which extends out from the second base51and around which the wire3wound around the distal-end pulley2is looped on the other side and a second coil spring53that biases the distal-end wire3in a pulling direction on the other side with respect to the second friction portion52, the second supporting part5being adapted to support the other side of the distal-end wire3.

It is here to be noted that the first coil spring43defines the first biasing portion and the second coil spring53defines the second biasing portion. The coil springs are not necessarily used for the first and the second biasing portion; they may be each formed of any member capable of biasing the distal-end wire3. The first43and the second coil spring53should preferably have the same biasing force.

The distal-end pulley2is rotatably attached to the given axis2a, and has the distal-end wire3wound along its outer circumference. As an example, the distal-end pulley2is preferably provided with a distal-end member21that rotates with the distal-end pulley2. For instance, the distal-end member21may be an electrode or the like of a high-frequency treatment tool.

The distal-end wire3wound around the distal-end pulley2is supported on one side to the first supporting part4and on the other side to the second supporting part5.

The first supporting part4includes the first base41, the first friction portion42and the first coil spring43. The first base41supports one side of the distal-end wire3, and is movable in a pulling or delivery direction of the distal-end wire3. Extending from a first step41aof the first base41toward the distal-end wire3, the first friction portion42is formed into a columnar configuration, and one side of the distal-end wire3wound around the distal-end pulley2is looped around the first friction portion42. The first coil spring43biases the distal-end wire3in the pulling direction on one end side of the distal-end wire3with respect to the first friction portion42.

The second supporting part5includes the second base51, the second friction portion52and the second coil spring53. The second base51supports one side of the distal-end wire3, and is movable in a pulling or delivery direction of the distal-end wire3. Extending out from a second step51aof the second base51toward the distal-end wire3, the second friction portion52is formed into a columnar configuration, and one side of the distal-end wire3wound around the distal-end pulley2is looped around the second friction portion52. The second coil spring53biases the distal-end wire3in the pulling direction on one end side of the distal-end wire3with respect to the second friction portion52.

In the slack correction mechanism1according to the first embodiment, one end of the distal-end wire3is fixed to one end of the first coil spring43, the other end of the distal-end wire3is fixed to the first base41of the first supporting part4, the other end of the distal-end wire3is fixed to one end of the second coil spring53, and the other end of the second coil spring53is fixed to the second base51of the second supporting part5. In other words, one end of the distal-end wire3is supported to the first supporting part4indirectly by way of the first coil spring43, and the other end of the distal-end wire3is supported to the second supporting part5indirectly by way of the second coil spring53.

Preferably, the slack correction mechanism1according to the first embodiment includes an interlocking part6activated such that when one of the first supporting part4and the second supporting part5moves in the pulling direction of the distal-end wire3, the other moves in the delivery direction of the distal-end wire3. Provision of the interlocking part6makes sure interlocking movement of the first supporting part4and the second supporting part5for unerring operation.

In the slack correction mechanism1according to the first embodiment, the interlocking part6is made up of a pinion61having mating teeth61aon its circumference. The first supporting part4includes a first rack44in mesh with the mating teeth61aof the pinion61, and the second supporting part5includes a second rack54in mesh with the mating teeth61aof the pinion61. In the slack correction mechanism1according to the first embodiment, the mating position where the mating teeth61aare in mesh with the first rack44is opposed to the mating position where the mating teeth61aare in mesh with the second rack54with respect to the center of rotation of the pinion61.

As the pinion61rotates, therefore, it causes the first supporting part4including the first rack44in mesh with the mating teeth61aand the second supporting part5including the second rack54to move in opposite directions.

The slack correction mechanism1according to the first embodiment may include a driving unit7for driving the interlocking part6, and an operating unit8that is put by an operator in operation to drive the driving unit7. The driving unit7here may be an electrically-operated member such as a motor, and the operating unit8here may be a joystick, a pointing device or a liquid crystal pad. Provision of the driving unit7and operating unit8makes sure smooth and unerring operation. Note here that the interlocking part6may be manually rotated by the operating unit8such as a handle without recourse to the driving unit7.

The operation of the slack correction mechanism1according to the first embodiment is now explained.

FIGS. 2, 3 and 4are schematic views of operating states of the slack correction mechanism1according to the first embodiment.

In the slack correction mechanism1according to the first embodiment, as the pinion61of the interlocking part6is rotated in a direction indicated by an action arrow C inFIG. 2, it causes the first supporting part4to move in a direction indicated by an action arrow D and the second supporting part5to move in a direction indicated by an action arrow E. At this time, there is a slack3ain the other side of the distal-end wire3looped around the second friction portion52of the second supporting part5, and there is an invisible elongation3bof one side of the distal-end wire3. However, these remain fixed by friction between the second friction portion52and the distal-end wire3.

As shown inFIG. 3, this slack3ais overcome as the distal-end wire3is pulled by the biasing force of the second coil spring53. As the wire3is then driven in the opposite direction as shown inFIG. 4, it starts to go into operation even when there is no movement by that slack amount. Typically, the distal-end member21does not usually start to move unless the first4and the second supporting part5are positioned symmetrically with respect to the pinion61, but in the slack correction mechanism1according to the first embodiment, the distal-end member21starts to go rapidly into operation before the first supporting part4and the second supporting part5are positioned symmetrically with respect to the pinion61.

With the slack correction mechanism1according to the first embodiment, the slack in the distal-end wire3is corrected by the first coil spring43and the second coil spring53. It is thus possible to reduce the operational delay of the distal-end member21for unerring operation. Further, because the distal-end wire3is not looped in its entirety, an assembling steps count diminishes, resulting in improved assembling capability and ease of initial tension adjustment as well. Furthermore, there is no need for using a caulking member or the like for connection of the distal-end wire3, possibly ending up with smooth operation.

The second embodiment is now explained.

FIG. 5is a schematic view of one example of the slack correction mechanism1according to the second embodiment.

The slack correction mechanism1according to the second embodiment is similar in structure to that of the first embodiment with the exception that the first supporting part4and the second supporting part5are structurally different from those in the first embodiment. Accordingly, only the structures of the first supporting part4and the second supporting part5are now explained.

In the slack correction mechanism1according to the second embodiment, the first base41includes a first tension pulley45that supports one end of the first coil spring43and is movable in the pulling direction of the distal-end wire3, and the second base51includes a second tension pulley55that supports one end of the second coil spring53and is movable in the pulling direction of the distal-end wire3. The distal-end wire3is wound around the first tension pulley45on one end side with respect to the first friction portion42, fixed at one end to the first base41, wound around the second tension pulley55on the other end side with respect to the second friction portion55, and fixed at the other end to the second base51.

To put it another way, in order from one end to the other end, the distal-end wire3is supported to the first base41, wound around the first tension pulley45, looped around the first friction portion42, wound around the distal-end pulley2, looped around the second friction portion52, wound around the second tension pulley55, and supported to the second base51.

The first base41is provided with a guide46for the first tension pulley, and the first tension pulley45is movably supported to that guide46. The distal-end wire3may be wound around the first tension pulley45in such a way as to form a part of a spiral. In other words, the position where the distal-end wire3is supported to the first base41may be spaced away from the surface where the distal-end wire3is looped around the first friction portion42.

The second base51is provided with a guide56for the second tension pulley, and the second tension pulley55is movably supported to that guide56. The distal-end wire3may be wound around the second tension pulley55in such a way as to form a part of a spiral. In other words, the position where the distal-end wire3is supported to the second base51may be spaced away from the surface where the distal-end wire3is looped around the second friction portion52.

The operation of the slack correction mechanism1according to the second embodiment is now explained.

FIGS. 6, 7 and 8are schematic views of operating states of the slack correction mechanism1according to the second embodiment.

In the slack correction mechanism1according to the second embodiment, as the pinion61of the interlocking part6is rotated in the direction indicated by an action arrow C inFIG. 6, it causes the first supporting part4to move in the direction indicated by an action arrow D and the second supporting part5to move in the direction indicated by an arrow action E. At this time, there is a slack3ain the other side of the distal-end wire3looped around the second friction portion52of the second supporting part5, and there is an invisible elongation3bon one side of the distal-end wire3. However, these remain fixed by friction between the second friction portion52and the distal-end wire3.

Such slack3ais overcome as the second tension pulley55moves the guide56for the second tension pulley under the biasing force of the second coil spring53to pull the distal-end wire3wound around the second tension pulley55. As the wire3is then driven in the opposite direction as shown inFIG. 8, it starts to go into operation even when there is no movement by that slack amount. Typically, the distal-end member21does not usually start to move unless the first supporting part4and the second supporting part5are positioned symmetrically with respect to the pinion61, but in the slack correction mechanism1according to the first embodiment, the distal-end member21starts to go rapidly into operation before the first supporting part4and the second supporting part5are positioned symmetrically with respect to the pinion61.

As described above, the slack correction mechanism1according to the second embodiment has, in addition to the advantage of the first embodiment, an advantage of reducing the elongation of the springs to half, because the distal-end wire3is looped around the first friction portion42and the second friction portion52, resulting in improved assembling capability, ease of length adjustment for the distal-end wire3and facility in initial tension adjustment. Further, the slack correction mechanism1according to the second embodiment makes use of the rack-and-pinion mechanism, contributing more to simple arrangement and unerring operation.

The third embodiment is now explained.

FIG. 9is a schematic view of one example of the slack correction mechanism1according to the third embodiment.

The slack correction mechanism1according to the third embodiment is similar in structure to that according to the second embodiment with the exception that the first supporting part4and second supporting part5and the interlocking part6are structurally different from those according to the second embodiment. Therefore, the structures of the first supporting part4and the second supporting part5and the structure of the interlocking part6are here explained.

In the slack correction mechanism1according to the third embodiment, the first supporting part4is provided with a first wall47that extends out in the same direction as the direction of extending the first friction portion42out from the first base41, and one end of the distal-end wire3and one end of the first coil spring43are supported to the first wall47. Likewise, the second supporting part5is provided with a second wall57that extends out in the same direction as the direction of extending the second friction portion52out from the second base51, and one end of the distal-end wire3and one end of the second coil spring53are supported to the second wall57.

It is here to be noted that instead of using the first wall47and the second wall57for the first supporting part4and the second supporting part5in the third embodiment, the positions of the distal-end wire3supported to the first base41and the second base51may be spaced away from the surfaces where the distal-end wire3is looped around the first friction portion42and the second friction portion52, as explained with reference to the second embodiment, and that the first wall47and the second wall57may be applied to the first supporting part4and the second supporting part5in the second embodiment as well.

In the slack correction mechanism1according to the third embodiment, the interlocking part6includes an interlocking pulley62, an interlocking wire63and an interlocking pulley guide64. The interlocking pulley62is movable with respect to the interlocking pulley guide64. The interlocking wire63is supported at one end to the first base41and at the other end to the second base51, and wound around the interlocking pulley62.

With the interlocking part6, therefore, the interlocking pulley62is first moved by the interlocking pulley guide64for initial tension setting for the distal-end wire3and interlocking wire63. Then, as the interlocking part6is actuated to rotate the interlocking pulley62, it causes one of the first supporting part4and the second supporting part5to be pulled and the other to be let out.

The operation of the slack correction mechanism1according to the third embodiment is now explained.

FIGS. 10, 11 and 12are schematic views of operating states of the slack correction mechanism1according to the third embodiment.

Referring to the slack correction mechanism1according to the third embodiment, as the interlocking part6goes into operation as shown inFIG. 10, it causes the interlocking pulley62to rotate in the direction indicated by an action arrow C and the first supporting part4to be pulled by the interlocking wire63. The first supporting part4moves in the direction indicated by an action arrow D, and the second supporting part5moves in the direction indicated by an action arrow E. At this time, there is a slack3ain the other side of the distal-end wire3looped around the second friction portion52of the second supporting part5, and there is an invisible elongation3bof one side of the distal-end wire3. However, these remain fixed by friction between the second friction portion52and the distal-end wire3.

Such slack3ais overcome as the second tension pulley55moves the second tension pulley guide56under the biasing force of the second coil spring53to pull the distal-end wire3wound around the second tension pulley55, as shown inFIG. 11. As the wire3is then driven in the opposite direction as shown inFIG. 12, it starts to go into operation even when there is no movement by that slack amount. Typically, the distal-end member21does not usually start to move unless the first supporting part4and the second supporting part5are positioned symmetrically with respect to the pinion61, but in the slack correction mechanism1according to the third embodiment, the distal-end member21starts to go rapidly into operation before the first supporting part4and the second supporting part5are positioned symmetrically with respect to the interlocking pulley62.

As described above, the slack correction mechanism1according to the third embodiment has, in addition to the advantage of the first embodiment, an advantage of temporarily stopping the distal-end wire3upon assembling, because the distal-end wire3is looped around the first friction portion42and the second friction portion52, resulting in further improved assembling capability, more facile length adjustment for the distal-end wire3and more facile initial tension adjustment. Further, the initial tension setting for the distal-end wire3and interlocking wire63may be made by movement of the interlocking pulley62by means of the interlocking pulley guide64, leading to more unerring initial tension adjustment.

The manipulator10incorporating the slack correction mechanism1according to one embodiment is now explained.

FIG. 13is illustrative of one example of the manipulator10according to the embodiment described herein.

As shown inFIG. 13, the manipulator10according to the embodiment described herein includes a distal-end part11, a cylindrical or tubular portion13, and a slack correction mechanism1.

Having a built-in distal-end pulley2, the distal-end part11is opposite to a subject of interest. As shown inFIG. 13, the distal-end part11may have an endoscope15aand a medical treatment tool15binside such as an end effector15. Note here that the endoscope15aincludes a viewing optical system for viewing a subject of interest, an imaging device for taking an image of the subject of interest passing through the viewing optical system, a lighting device for lighting the subject of interest, etc.

The tubular portion13is provided to connect an operating unit8side to a distal-end part11side, and formed of a flexible or hard tubular member. The tubular portion13houses a distal-end wire3inside for protective purposes.

The operating unit8includes a grip81, a joystick82, and so on. While the grip81according to the embodiment here is shown in a rod-like member form, it is to be understood that it may take a multi-joint arm form, or a form suitable for operation of the medical treatment tool15bsuch as a scissors' handle. The joystick82is provided for operation of the orientation of the distal-end part11. Note here that the operating unit8may have in it the first supporting part4and the second supporting part5, the interlocking part6and the driving unit7forming part of the slack correction mechanism1.

With the manipulator10having such structure as described above, as the operating unit8is put by an operator in operation, it causes one side of the distal-end wire3wound around the pulley2to be hauled, and the distal-end part11to be bent in the hauling direction of the distal-end wire3with respect to the tubular portion13, thus enabling the distal-end part11to be directed toward the subject of interest.

As described above, the manipulator10according to the embodiment here includes the distal-end part11that takes rotatable hold of the distal-end pulley21by pulling or letting out the distal-end wire3, and the slack correction mechanism1. It is thus possible for the operator to put the manipulator in unerring operation.

The surgical system90is now explained as an example of the manipulator system to which the manipulator1according to the embodiment described herein is applied.

FIG. 14is illustrative of the surgical system90to which the manipulator1according to the embodiment described herein is applied, andFIG. 15is illustrative in system architecture of the surgical system90to which the manipulator1according to the embodiment described herein is applied.

The manipulator1shown inFIG. 14is applied to the surgical system90according to the embodiment described herein. The surgical system90includes a manipulator1including an operating unit8operated by an operator O, a distal-end part11shown inFIG. 13, which includes a distal-end endoscope or other medical treatment tool15bthat is capable of insertion through a soft organ such as the large intestine of a patient P lying down on an operating table BD, and a tubular portion13that transmits an input from the operating unit8to the distal-end part11and is capable of being partially inserted into the organ, a control unit91for controlling the manipulator1, and a display unit92for displaying an image acquired through the manipulator1.

As shown inFIG. 14, the operating unit8includes a pair of operating handles mounted on an operating base, a footswitch mounted on the floor surface, etc. The operating unit8may have a multi-joint structure. The angle of the operating unit8in operation is acquired from an angle acquisition component such as an encoder and, in response to the resultant signal, the control unit91then puts the medical treatment tool15bmounted on the distal end of the distal-end part11into operation by way of a driver91a, as shown inFIG. 15.

An image acquired through the endoscope15ais sent out to an image processor91bin the control unit91, and the image processed in the image processor91bis displayed on the display unit92. The operator O then operates the manipulator1while viewing an image displayed on the display unit92.

According to such surgical system90, it is possible to have the advantages of the slack correction mechanism1and display unerring images asked for by the operator, and for the operator to put the manipulator into more unerring operation.

As described above, the slack correction mechanism1according to the embodiment described herein includes a distal-end pulley2that is rotatable with respect to a given axis2a, a distal-end wire3wound around the distal-end pulley2, a first supporting part4including a first base41, a first friction portion42which extends out from the first base41and around which the distal-end wire3wound around the distal-end pulley2is looped on one side and a first coil spring43that biases the distal-end wire3in a pulling direction on one end side with respect to the first friction portion42, the first supporting part4being adapted to support one side of the distal-end wire3, and a second supporting part5including a second base51, a second friction portion52which extends out from the second base51and around which the distal-end wire3wound around the distal-end pulley2is looped on the other side and a second coil spring53that biases the distal-end wire3in a pulling direction on the other side with respect to the second friction portion52, the second supporting part5being adapted to support the other side of the distal-end wire3. It is thus possible to reduce the operational delay of the distal-end member21for unerring operation. Further, because the distal-end wire3is not looped in its entirety, an assembling steps count diminishes, resulting in improved assembling capability and ease of initial tension adjustment as well. Furthermore, there is no need for using a caulking member or the like for connection of the distal-end wire3, possibly ending up with smooth operation.

The slack correction mechanism1according to the embodiment described herein further includes an interlocking part6activated such that when one of the first4and the second supporting part5moves in a pulling direction of the distal-end wire3, the other moves in a delivery direction of the distal-end wire3. It is thus possible to interlock mutual movements of the first4and the second supporting part5for unerring operation.

The slack correction mechanism1according to the embodiment described herein further includes a driving unit7for driving the interlocking part6, and an operating unit8that is put by the operator in operation to drive the driving unit7. It is thus possible to achieve smooth and unerring operation.

In the slack correction mechanism1according to the embodiment described herein, the interlocking part6includes a pinion61that has mating teeth61aon its outer circumference and rotates with respect to a given axis, and the first supporting part4includes a first rack44in mesh with the pinion61while the second supporting part5includes a second rack54in mesh with the pinion61. It is thus possible to achieve unerring operation with the use of a simplified structure.

In the slack correction mechanism1according to the embodiment described herein, the interlocking part6includes an interlocking pulley62having a movable axis, and an interlocking wire63wound around the interlocking pulley62and fixed at one end to the first base41and at the other end to the second base51. It is thus possible to move the interlocking pulley62by means of the interlocking pulley guide64for initial tension setting for the distal-end wire3and interlocking wire63, resulting in unerring initial tension adjustment.

In the slack correction mechanism1according the embodiment described herein, one end of the distal-end wire3is fixed to one end of the first coil spring43, the other end of the first coil spring43is fixed to the first base41, the other end of the distal-end wire3is fixed to one end of the second coil spring53, and the other end of the second coil spring53is fixed to the second base51. It is thus possible to achieve unerring operation with the use of a simplified structure.

In the slack correction mechanism1according to the embodiment described herein, the first supporting part4supports one end of the first coil spring43and includes a first tension pulley45that is movable in a pulling direction of the distal-end wire3, the other end of the first coil spring43is fixed to the first base41, the second supporting part5supports one end of the second coil spring53and includes a second tension pulley55that is movable in a pulling direction of the distal-end wire3, the other end of the second coil spring53is fixed to the second base51, the distal-end wire3is wound around the first tension pulley45on one end side with respect to the first friction portion43and fixed at one end to the first base41, and the distal-end wire3is wound around the second tension pulley55on the other end side with respect to the second friction portion53and fixed at the other end to the second base51. It is thus possible to make the extension/contraction distance of the first43and the second coil spring53shorter than achieved in the first embodiment.

The manipulator10according to the embodiment described herein includes a distal-end part11that takes rotatable hold of the distal-end pulley21by pulling or letting out the distal-end wire3, and a slack correction mechanism1. In addition to the advantage of the slack correction mechanism1, it is thus possible for the operator to put the manipulator into unerring operation.

The manipulator system90according to one embodiment includes a manipulator10, a system control unit91for controlling the manipulator10, and a display unit92for displaying an image acquired through the manipulator10, wherein the manipulator10includes an endoscope15ahaving a viewing optical system, an imaging device and a lighting optical system, and the system control unit91displays an image acquired through the endoscope15aon the display unit92. In addition to the advantage of the slack correction mechanism1, it is possible to display unerring images asked for by the operator, and it is possible for the operator to put the manipulator into more unerring operation.

While the embodiments have been each explained with reference to one distal-end wire3, it is to be understood that a pair of distal-end wires may be each fixedly wound around the distal-end pulley2, and the distal-end wire3may be formed of a single wire, a stranded wire, a knitted wire, a sheet-form wire, and so on.

It is here to be appreciated that the invention is in no sense limited to such embodiments as described above. While the explanation of some embodiments embraces numerous specific details for illustration, it would be obvious to those skilled in the art that diverse variations or modifications made thereto are included within the scope of the invention. In other words, illustrative embodiments of the invention are described without excluding generality from the claimed inventions and imposing any limitation thereon.

REFERENCE SIGNS LIST