Abstract:
A manipulator includes a main arm, of which the proximal end bears a drive, and a proximal manipulation structure, and of which the distal end bears a controlled distal structure that may itself bear a surgical tool. The main arm passes through a surgical trocar. The proximal manipulation structure includes two opposed contact zones and stress sensors positioned in a central zone between the two opposed contact zones. The stress sensors operate the drive as a function of the stresses applied to the contact zones in order to produce the pivoting and rotating movements of the surgical tool with respect to the main arm. This ensures that there is optimal decoupling of the movements in the various degrees of freedom, thus making it easier to obtain movements through stressing operations that are natural to the operating surgeon.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention concerns guide and manipulator devices enabling the movements of a manipulator instrument situated inside an operating area to be controlled from outside the operating area. 
         [0002]    The invention concerns in particular a guide and manipulator device of this kind for controlling a surgical instrument in minimally invasive surgical applications carried out endoscopically. 
         [0003]    In recent years, minimally invasive endoscopic surgery has expanded considerably. 
         [0004]    For this purpose essentially two types of surgical instrument guide and manipulator device have been designed. 
         [0005]    In the first type of guide and manipulator device, described for example in the document FR 2 713 129 A or FR 2 876 271 A, the surgical instrument is placed at the end of a portable manipulator essentially having a main arm with a proximal end and a distal end. The proximal end of the arm carries a proximal manipulator structure adapted to generate movement instructions as a function of forces applied by a hand of an operator. A distal controlled structure is carried by the distal end of the main arm and is mobile relative to said distal end of the main arm with at least two degrees of freedom in transverse pivoting and possibly one degree of freedom in axial rotation. Movements applied by the operator to the proximal manipulator structure are transmitted by transmission means in the main arm and reproduced by the distal controlled structure. 
         [0006]    During a surgical operation, the main arm is passed through the skin of a patient, the proximal manipulator structure remaining outside the body of the patient, the distal controlled structure then being inside the body of the patient to perform the surgical action. 
         [0007]    In the device from the document FR 2 713 129 A, the proximal manipulator structure has contact areas for two fingers of an operator to bear on, the contact areas being disposed at the end of a lever articulated to the proximal end of the main arm by a ball-joint. The distal controlled structure is disposed at the end of a distal lever itself articulated to the distal end of the main arm by a second ball-joint. The two ball-joints are mechanically linked to each other so that the distal ball-joint reproduces the rotation of the proximal ball-joint. 
         [0008]    A first drawback of this device is the difficulty of performing a precise surgical action. It is found difficult to apply to the proximal manipulator structure forces enabling precise production of pure rotation movements or pure translation movements of the distal controlled structure. 
         [0009]    A second drawback of this device is the relatively small relative angular movement possible in movements in pivoting of the distal controlled structure about a transverse axis. 
         [0010]    The same drawbacks are also found in the device described in the document FR 2 876 271 A. 
         [0011]    That document further describes an embodiment in which the proximal manipulator structure is offset away from the main arm and the transmission of movement between the proximal manipulator structure and the distal controlled structure is effected via drive means supplied with power by an external power supply. 
         [0012]    In the second type of guide and manipulator device for surgical instruments as described for example in the document U.S. Pat. No. 5,797,900 A, the surgical instrument is actuated by a remote-controlled robot. A master arm, operable by an operator, is completely separate from a slave arm that carries the surgical instrument. The master arm and the slave arm are usually articulated arms having at least six degrees of freedom of movement; the master arm is provided with sensors detecting the forces applied to it, and mechanical forces are applied to the slave arm by motorized actuators that respond to the signals produced by the master arm sensors. Thus the connection between the master arm and the slave arm is provided by electrical signals and the robot is generally placed at a distance from the master arm. 
         [0013]    Another example of a remote-controlled manipulator of this second type of guide and manipulator device is described in the document US 2003/0109957 A1. This document describes in more detail a proximal manipulator structure in the form of a handgrip connected to a fixed support by five successive articulations each provided with movement sensors for remotely controlling a slave arm carrying a surgical instrument. Starting from the fixed support, a master shoulder rotation commands lateral pivoting of the slave arm about the trocar in a first longitudinal plane, a master elbow rotation commands lateral pivoting of the slave arm about the trocar in a second longitudinal plane, a master forearm axial translation commands axial translation of the slave arm in the trocar, a master wrist axial rotation commands axial rotation of the slave arm in the trocar and, finally, transverse rotation of the handgrip commands rotation of the slave arm. Except for the wrist transverse rotation sensor, all the movement sensors are situated in connecting areas that are clearly separated from the wrist. This device with successive articulations is not applicable to a portable manipulator because the slave arm must then be held mechanically by the proximal manipulator structure, and the articulations do not allow this. Furthermore, in the above document, the surgical instrument is not mobile relative to the slave arm in orientation and in rotation. 
         [0014]    Because of their complexity, such remote-controlled manipulators are bulky and costly and have high maintenance costs. The operator actuates the master arm at a position far from the patient, with the result that the operator cannot act to administer rapid emergency medical treatment to the patient. Also, the bulk of the system necessitates lengthy preparation and total reorganization of the operating theatre and working procedures. 
         [0015]    It will also be noted that these documents describe a distal controlled structure in which the surgical tool cannot execute an axial rotation movement about its own axis, as is sometimes necessary in surgical procedures, in which case the surgical procedures necessitate the intervention of a plurality of movements on different axes, which movements must be simultaneous and synchronized, and this necessitates relatively complex computer means and further complicates the device. 
       SUMMARY OF THE INVENTION 
       [0016]    The problem addressed by the present invention is to design a new type of manipulator that makes it possible to make surgical actions more precise without necessitating a large overall size and a large investment. 
         [0017]    The invention aims in particular to make surgical actions more precise without recourse to a remote-controlled robot. 
         [0018]    The invention stems from the observation that known portable manipulators do not discriminate effectively the various movement stresses applied to the proximal manipulator structure. In particular, a stress for relative pivoting about a transverse axis applied to the proximal manipulator structure generally induces not only a similar relative pivoting movement about a transverse axis of the distal controlled structure relative to the main arm but also a movement of overall pivoting and of overall axial translation of the main arm itself relative to the body of the patient. 
         [0019]    To avoid these drawbacks, the invention proposes a manipulator including:
       a main arm having a proximal end and a distal end,   a proximal manipulator structure carried by the proximal end of the main arm, to which it is connected by a connecting structure, having at least two opposite contact areas conformed to have two opposite parts of a hand of an operator bear on them, and including stress sensors adapted to generate movement instructions as a function of the stresses applied by the hand of the operator,   a distal controlled structure, carried by the distal end of the main arm and mobile relative to said distal end with at least two degrees of freedom in transverse relative pivoting and one degree of freedom in axial rotation on itself,   drive means supplied with power by a power supply and adapted to generate movements as a function of movement instructions received from the proximal manipulator structure, and   mechanical transmission means accommodated in the main arm, mechanically coupled to the drive means and adapted to transmit movements of the drive means to the distal controlled structure to generate the movements of the distal controlled structure as a function of the movement instructions coming from the proximal manipulator structure,
 
wherein:
   the connecting structure is disposed in an intermediate area between the opposite contact areas of the proximal manipulator structure, and   stress sensors are disposed in said connecting structure and adapted to generate the instructions for movement of the distal controlled structure relative to the main arm with at least two degrees of freedom of movement as a function of the stresses detected in said connecting structure.       
 
         [0027]    Because stress sensors are disposed and arranged in such a manner as to generate instructions for movement of the distal controlled structure as a function of the stresses present in and detected in a connecting structure situated between the two opposite contact areas, it is possible to discriminate movement stresses applied to the proximal manipulator structure according to the different degrees of freedom of the manipulator. 
         [0028]    According to a first possibility, the connecting structure includes an articulation and the sensors are displacement sensors sensitive to the relative displacement of the main arm and the proximal manipulator structure on either side of the articulation. 
         [0029]    According to a second possibility, the connecting structure is an elastically deformable structure and the sensors are strain gauges sensitive to deformation of the connecting structure. 
         [0030]    In a first practical embodiment:
       the proximal manipulator structure is offset radially away from the longitudinal axis of the main arm,   the opposite contact areas are, in a median position, aligned in a direction at an angle of approximately 45° to the longitudinal axis of the main arm, and   the stress sensors disposed in the connecting structure are adapted to generate the instructions for movement of the distal controlled structure in accordance with the two degrees of freedom in relative transverse pivoting and the one degree of freedom in axial rotation on itself.       
 
         [0034]    As a result, centered relative pivoting stresses applied to the proximal manipulator structure have very little effect on other possible movements of the manipulator, notably movements of overall translation and overall pivoting of the main manipulator arm. This ensures good discrimination of the possible movements of the manipulator according to its different degrees of freedom whilst all movements are commanded by application of stresses to only two opposite contact areas of the proximal manipulator structure. 
         [0035]    In a second practical embodiment:
       the connecting structure is centered on the longitudinal axis of the main arm,   the stress sensors disposed in the connecting structure are adapted to generate the instructions for movement of the distal controlled structure in accordance with the two degrees of freedom of movement in relative transverse pivoting, and   the movements of axial rotation on itself of the distal controlled structure are commanded by the movement instructions generated by an additional stress sensor carried by the proximal manipulator structure and adapted to be actuated by a finger of the user acting on the proximal manipulator structure.       
 
         [0039]    As a result, discrimination of the possible movements of the manipulator according to its different degrees of freedom is further improved. 
         [0040]    The manipulator defined above is a portable unit that the operator can hold in his hand during a surgical operation. Such a manipulator may advantageously further include an intermediate bearing member for the main arm in which the main arm can slide axially and which can pivot with a spherical overall pivoting movement. This facilitates guiding the distal controlled structure for total control of its positioning relative to an intervention area. 
         [0041]    The main arm may preferably further have a movement of overall axial rotation relative to the intermediate bearing member. 
         [0042]    In practice, a manipulator as defined above may have a distal controlled structure that comprises a distal support articulated to the end of the main arm, adapted to oscillate on either side of the longitudinal axis of the main arm in relative pivoting movement with two degrees of freedom about intersecting transverse axes. The articulated distal support carries a tool-holder rotary shaft adapted to turn in axial rotation on itself on the distal support. This imparts to the surgical tool placed on the manipulator all the required degrees of relative movement. 
         [0043]    In all cases, the stress sensors, the drive means and the mechanical transmission means may advantageously be adapted so that:
       a stress for centered relative pivoting applied to the proximal manipulator structure produces similar relative pivoting of the distal support of the distal controlled structure, and   a stress for axial rotation on itself applied to the proximal manipulator structure produces similar relative axial rotation of the tool-holder rotary shaft.       
 
         [0046]    To carry out certain surgical actions, the distal controlled structure must be adapted to reproduce easily relative pivoting movements of large amplitude about two intersecting transverse axes. Thus a second aspect of the invention proposes a new distal controlled structure making it possible both to reproduce faithfully the relative pivoting movements and to increase the maximum amplitude of such movements relative to the capacities offered by known devices, whilst allowing axial rotation movements on itself of a tool carried by the distal controlled structure. 
         [0047]    To provide this great amplitude of movements of relative pivoting of the distal controlled structure relative to the main arm, the invention proposes a distal controlled structure that includes:
       at the distal end of the main arm, a female articulation member with a hemispherical distal cavity,   an articulated distal support a male articulation member in the form of a hollow hemispherical flange having a hemispherical external surface and an interior void wide open toward its base,   the male articulation member being engaged in the distal hemispherical cavity of the female articulation member with its interior void oriented toward the distal hemispherical cavity,   a plurality of control lines extending in the main arm, mechanically coupled to the drive means and engaged at the periphery of the hemispherical external surface of the male articulation member to command pivoting thereof by traction on the control lines,   a tool-holder rotary shaft in the form of an output shaft rotatably mounted on a radial bearing of the male articulation member and carrying a tool or a tool-holder,   an input shaft mounted to rotate in an axial bearing of the female articulation member and engaged longitudinally in the main arm, and   a homokinetic transmission that connects the input shaft to the output shaft, allowing movements of transverse pivoting of the male articulation member in the female articulation member.       
 
         [0055]    This produces a distal controlled structure that itself has two degrees of freedom in relative pivoting about intersecting transverse axes and imparting to a surgical tool that it carries a degree of freedom in axial rotation on itself, these relative movements of pivoting and rotation on itself being totally independent of each other, and the relative pivoting movements having amplitudes of the order of 70° on either side of the longitudinal axis of the main arm. 
         [0056]    A distal controlled structure of this kind may be used on a manipulator independently of the presence or the absence of the particular movement discrimination means referred to above. 
         [0057]    An ongoing concern is to produce a portable manipulator that is both less costly and easily manipulated. Thus a third aspect of the invention further aims to reduce the weight and the overall size of such a manipulator. 
         [0058]    To this end, the invention proposes a design of such a manipulator in which the main shaft is slidably engaged in a passage of a surgical trocar or a support arm forming an intermediate bearing member, the surgical trocar or the support arm having connecting means with sliding contacts for transmitting electrical power and control and monitoring signals between the main arm and an external power supply and processing system. 
         [0059]    As a result, the power supply and processing system may be offset from the manipulator itself, and have no effect on its weight and overall size in the vicinity of the operating area. 
         [0060]    Such a trocar or support arm with sliding contacts may be used independently of the presence or the absence of the other means described above for discriminating movement or for increasing the amplitude of relative pivoting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0061]    Other objects, features and advantages of the present invention will emerge from the following description of particular embodiments given with reference to the appended figures, in which: 
           [0062]      FIG. 1  shows diagrammatically an operator actuating two manipulators of the present invention to carry out a surgical operation; 
           [0063]      FIG. 2  is a diagrammatic side view of a manipulator of one embodiment of the present invention; 
           [0064]      FIG. 3  shows the manipulator from  FIG. 2  during a small pivoting movement of the distal controlled structure about its transverse axis; 
           [0065]      FIG. 4  shows the manipulator from  FIG. 2  during a large pivoting movement about a transverse axis of the main arm and during axial rotation of the distal controlled structure; 
           [0066]      FIGS. 5 ,  6  and  7  show in perspective the movements of the manipulator during suturing to insert a suturing needle into tissue to be sutured; 
           [0067]      FIG. 8  is a more detailed perspective view of a manipulator of the  FIG. 2  embodiment; 
           [0068]      FIG. 9  is a perspective view of the manipulator from  FIG. 8  in a position with a different orientation of the distal controlled structure; 
           [0069]      FIGS. 10 and 11  are diagrammatic views showing rotation and pivoting movements in prior art manipulators; 
           [0070]      FIG. 12  shows diagrammatically pivoting and rotation movements of a manipulator of a preferred embodiment of the present invention; 
           [0071]      FIGS. 13 and 14  are diagrammatic side views showing two embodiments of stress sensors for the proximal manipulator structure; 
           [0072]      FIG. 15  is a perspective view of a distal controlled structure of one particular embodiment of the present invention; 
           [0073]      FIG. 16  is a view in longitudinal section of the distal controlled structure from  FIG. 15 ; 
           [0074]      FIG. 17  is a diagrammatic view in longitudinal section of the structure from  FIG. 16  in a centered position; 
           [0075]      FIG. 18  is a longitudinal section of the structure from  FIG. 16  in an intermediate pivoting position; 
           [0076]      FIG. 19  is a longitudinal section of the structure from  FIG. 16  in an extreme pivoting position; 
           [0077]      FIG. 20  is a diagrammatic side view of a manipulator of the invention with a surgical trocar; 
           [0078]      FIG. 21  shows the manipulator from  FIG. 20  in perspective in a disassembled state; 
           [0079]      FIG. 22  shows the manipulator from  FIG. 21  in an assembled state. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0080]    As shown in  FIG. 1 , during a minimally invasive surgical operation, an operator  100  has to act on tissue  101  situated inside the body  102  of a patient. The operator manipulates with his hands  103  and  104  two manipulators  105  and  106  for effecting a suture, for example, by passing a curved needle  110  through the tissue  101 . 
         [0081]    Each of the two manipulators  105  and  106  passes through the skin  107  of the body  102  of the patient, a distal portion of each of the manipulators  105  and  106  thus being situated inside the body  102  of the patient, while a proximal portion is outside the body so that it can be manipulated by the operator  100 . 
         [0082]    The invention aims to enable the operator  100  to execute natural and simple movements of his hands  103  and  104  to execute the necessary movements of the respective surgical tools  105   a  and  106   a  disposed at the distal ends of the respective manipulators  105  and  106 . 
         [0083]    Consider next the  FIG. 2  diagram, which shows in more detail the general structure of a manipulator  105  of one embodiment of the invention in a position in which it passes through the skin  107  of the patient in order to perform a surgical operation. 
         [0084]    The manipulator  105  includes a main arm  1  having a proximal end la and a distal end  1   b,  a proximal manipulator structure  2 , a distal controlled structure  3  and a surgical trocar  10 . 
         [0085]    The surgical trocar  10  is engaged in a perforation in the skin  107  of the patient and forms a passage in which the main arm  1  can slide axially to perform an overall translation movement and the main arm  1  can turn in overall axial rotation about its longitudinal axis I-I. 
         [0086]    The surgical trocar  10  can itself pivot to either side of the axis of the perforation in the skin  107  of the patient to allow overall pivoting movements of the main arm  1  about a pivot point consisting of the perforation in the skin  107  of the patient. 
         [0087]    The proximal manipulator structure  2  includes at least two opposite contact areas  2   a  and  2   b  conformed to have two opposite parts of a hand of the operator bear on them. Stress sensors  2   c  are disposed in such a manner as to generate movement instructions as a function of the stresses present in a connecting structure  2   d  that connects the proximal manipulator structure  2  to the main arm  1  and is situated between the two opposite contact areas  2   a  and  2   b.    
         [0088]    The distal controlled structure  3  is carried by the distal end  1   b  of the main arm  1 , and is mobile relative to said distal end  1   b  with at least two degrees of freedom in transverse relative pivoting and one degree of freedom in axial rotation on itself. 
         [0089]    Drive means  5  supplied with power by a power supply included in power supply and control means  200  are adapted to generate movements as a function of movement instructions received from the proximal manipulator structure  2 . In the embodiment shown in the figures, the power supply and control means  200  are away from the manipulator  105  to reduce its weight and bulk. Nevertheless, placing the power supply and control means  200  on the main arm  1  itself may be also envisaged if these power supply and control means  200  are sufficiently light and compact. 
         [0090]    Mechanical transmission means  6  accommodated in the main arm  1  transmit to the distal controlled structure  3  movements produced by the drive means  5  to generate movements of the distal controlled structure  3  as a function of movement instructions received from the proximal manipulator structure  2 . 
         [0091]      FIG. 3  relates to a first type of movement of the distal controlled structure  3 . This is a movement of relative pivoting, or of small radius pivoting relative to the main arm  1 , as shown by the arrow  7   b,  about a distal transverse axis. This movement shown by the arrow  7   b  is produced by relative pivoting on itself of the proximal manipulator structure  2  with relative pivoting about a proximal transverse axis as shown by the arrow  7   a.  It will be noted that the distal transverse axis about which the rotation  7   b  of the distal controlled structure  3  may take place may have any radial orientation around the longitudinal axis I-I of the main arm  1 . To this end, the proximal manipulator structure  2  is pivoted about a proximal transverse axis that may also assume any radial orientation about a longitudinal axis of the proximal manipulator structure  2 . In other words, the distal controlled structure  3  has two degrees of freedom in transverse pivoting relative to the longitudinal axis I-I of the main arm  1 . The figure also shows a movement of overall axial rotation  6   a  of the main arm  1  about its longitudinal axis I-I. 
         [0092]    Consider next  FIG. 4 , which shows two other movements of the distal controlled structure  3 : on the one hand, a overall pivoting or large-radius pivoting movement, as shown by the arrow  8   b,  which is a rotation of the main arm  1  about a transverse intermediate axis in the area occupied by the surgical trocar  10 , this overall pivoting movement being produced by a transverse stress  8   a  applied by the hand of the operator to the proximal manipulator structure  2  and; on the other hand, a movement of axial rotation on itself as shown by the arrow  9   b,  produced by a similar axial rotation on itself stress  9   a  applied by the hand of the operator to the proximal manipulator structure  2 .  FIG. 4  further shows a movement of axial overall translation of the main arm  1  in the surgical trocar  10 , as shown by the arrow  11 . 
         [0093]    Such movements are necessary to produce the various surgical actions simply and ergonomically. The movements may differ in amplitude and be combined with each other as a function of the action to be performed. 
         [0094]    Consider by way of example  FIGS. 5 to 7 , which show the necessary movements for an action of passing a suture needle  110  through the tissue  101 . 
         [0095]    In this case, the distal controlled structure  3  carries a surgical tool  105   a  in the form of forceps with which the operator grips a proximal end of the curved suture needle  110 . The operator can thus pass the curved suture needle  110  through the tissue  101  as shown in the figures by applying to the distal controlled structure  3  appropriate movements of relative pivoting, relative rotation on itself, overall pivoting, overall rotation and overall translation. It is clear that the surgical action is relatively complex and that it is entirely beneficial to simplify the movements that the operator must apply to the proximal manipulator structure  2  to perform this action. 
         [0096]    The precision of the surgical action in particular necessitates that the movements applied by the operator to the proximal manipulator structure  2  are as natural as possible in order for everything to appear to the operator as if they were holding the curved suture needle  110  in his hand. 
         [0097]    To understand this difficulty, and the benefit of the invention, consider next  FIGS. 10 to 12 . 
         [0098]      FIG. 10  shows a known manipulator structure, such as that described in the documents FR 2 713 129 A and FR 2 876 271 A, for example. 
         [0099]    In this case, there are a proximal manipulator structure  2 , a main arm  1 , a surgical trocar  10  and a distal controlled structure  3 . 
         [0100]    The proximal manipulator structure  2  includes two offset contact areas  2   a  and  2   b  and is articulated to the proximal end la of the main arm  1  in an articulation type connecting area  2   e,  and so is adapted to pivot about the articulation  2   e.  The main arm  1  can pivot with the surgical trocar  10  relative to the skin of the user about a transverse pivot axis  10   a.    
         [0101]    To produce a movement of relative pivoting  7   b  of the distal controlled structure  3 , the operator must apply to the proximal manipulator structure  2  transverse forces F 1  and F 2  tending to cause the proximal manipulator structure  2  to pivot about the articulation  2   e.  Because, in the prior art documents, the proximal manipulator structure  2  is offset away from the articulation  2   e,  the transverse forces F 1  and F 2  are in the same direction, and simultaneously induce a torque causing overall pivoting of the main arm  1  about the axis  10   a.  Thus the natural movement of the operator to pivot the proximal manipulator structure  2  and produce a relative pivoting movement  7   b  simultaneously induces a movement of overall pivoting  8   b  and possibly a movement of overall translation  11 . 
         [0102]    If the operator wishes to achieve a movement of pure relative pivoting  7   b,  they must then compensate the translation movement  11  and the overall pivoting movement  8   b,  which is unnatural and has to be learned, requiring continuous visual monitoring of the operating field. 
         [0103]    To obtain pure overall translation as shown by the arrow  11 , the intuitive action of the operator is to pull or push the manipulator on the axis of the main arm  1 . Applying such parallel and equal forces F′ 1  and F′ 2  to the opposite contact areas  2   a  and  2   b  simultaneously produces relative pivoting of the proximal manipulator structure  2  about the articulation  2   e.  The operator must then correct this by modifying the direction of the applied forces or by simultaneously applying a compensation torque to the proximal manipulator structure  2 , which is unnatural. 
         [0104]    In  FIG. 11 , the pure overall translation shown by the arrow  11  can be obtained slightly more easily with the known devices by forces F 1  and F 2 , but this is merely a special case in which the proximal manipulator structure  2  is on the axis of the main arm  1 . 
         [0105]    In  FIG. 10 , to produce an overall pivoting movement as shown by the arrow  8   b,  the operator must apply to the contact areas  2   a  and  2   b  forces F 1  and F 2  in a direction transverse to the direction of the main arm  1  to obtain pivoting thereof about the transverse axis  10   a.  Because the proximal manipulator structure  2  is offset away from the articulation  2   e,  this stress simultaneously produces a torque causing the proximal manipulator structure  2  to pivot about the articulation  2   e,  as shown by the arrow  7   a.  This stress simultaneously produces undesirable relative pivoting  7   b  of the distal controlled structure  3 . The operator must therefore compensate this unwanted movement by simultaneously applying a compensating torque to the proximal manipulator structure  2 . 
         [0106]    Consider next  FIG. 12 , which shows diagrammatically the movements in a manipulator of a preferred embodiment of the present invention. In this case, the articulation  2   e  is situated on the longitudinal axis I-I of the main arm  1 . 
         [0107]    In all cases, the application of two equal forces F 1  and F 2 ′ in the same direction to the opposite contact areas  2   a  and  2   b  does not induce any torque causing the proximal manipulator structure  2  to rotate about its articulation  2   e  because the two opposite contact areas are aligned with the articulation  2   e.  Thus stresses to produce overall pivoting about the axis  10   a  or overall translation  11  induce no component of relative pivoting  7   a  of the proximal manipulator structure  2  and of consequential relative pivoting  7   b  of the distal controlled structure  3 . 
         [0108]    Similarly, relative pivoting about the articulation  2   e  as shown by the arrow  7   a  is obtained by applying two equal and opposite forces F 1  and F 2 , which does not lead to any stress in overall translation  11  or in overall pivoting  7   a  about the axis  10   a.    
         [0109]    To discriminate effectively the movement of axial rotation on itself of the distal controlled structure  3 , this rotation movement is controlled by an additional stress sensor  2   j  carried by the proximal manipulator structure  2  and actuated by a free finger of the user&#39;s hand when acting on the proximal manipulator structure  2 . Such a sensor  2   j  may be a cursor, a button, a thumbwheel, for example. 
         [0110]    The invention thus achieves perfect dissociation of the movements, the operator being able to apply intuitive movements that normally lead to the required movements when holding a surgical instrument in the hand. 
         [0111]    Consider next  FIGS. 8 and 9  which show in perspective a manipulator structure of another embodiment of the invention. 
         [0112]    These figures include the essential parts of the manipulator from  FIGS. 2 to 4 , these essential parts are identified by the same reference numbers. The trocar is not shown. 
         [0113]    There is seen at the distal end of the manipulator  105  a surgical instrument  105   a  in the form of forceps held by the distal controlled structure  3 . In  FIG. 8 , the surgical instrument  105   a  is on the axis of the main arm  1 . In  FIG. 9 , the surgical instrument  105   a  has pivoted relative to the main arm  1 . 
         [0114]    These figures show an advantageous embodiment of a proximal manipulator structure  2 . 
         [0115]    This proximal manipulator structure  2  comprises two coplanar rings constituting the opposite contact areas  2   a  and  2   b,  conformed so that the operator can pass a finger through each of the two rings  2   a  and  2   b.    
         [0116]    The user preferably inserts a thumb into one of the rings and a finger of the same hand into the other ring. 
         [0117]    The rings  2   a  and  2   b  are connected by a crosspiece  2   f  which is itself connected to the drive means  5  and to the main arm  1  by a connecting arm  2   g.  The crosspiece  2   f  and the connecting arm  2   g  form a structure that carries the rings or opposite contact areas  2   a  and  2   b.  An intermediate area of the connecting arm  2   g  constitutes the central connecting structure  2   d  in which it is required to sense the stresses applied by the operator. The connecting arm  2   g  is oriented in a radial direction or at least strongly inclined relative to the longitudinal axis I-I of the main arm  1  so that the rings  2   a  and  2   b  are offset radially away from the main arm  1  and the rings  2   a  and  2   b  are aligned in a direction II-II at an angle of approximately 45° to the axis I-I. 
         [0118]    According to a first possibility, the connecting structure  2   d  of the arm  2   g  is an articulated area and the sensors  2   c  are then movement sensors, for example encoders or potentiometers, adapted to evaluate the relative pivoting of the two successive sections of the connecting arm  2   g  relative to each other to produce the movement instructions. Accordingly, in this embodiment, the sensors  2   c  are in the connecting structure  2   d  itself. 
         [0119]    According to another possibility, the connecting structure  2   d  of the connecting arm  2   g  is an elastically deformable structure, the sensors then being strain gauges  2   c  sensitive to deformation of this connecting structure  2   d.    
         [0120]    Placing the strain gauges away from the centre of the connecting structure  2   d  may also be considered, combined with correcting the strains measured by the sensors  2   c  in an offset area by calculation to evaluate the strains present in the intermediate area  2   d.    
         [0121]    Consider next  FIGS. 13 and 14 , which show two other embodiments of the proximal manipulator structure  2 . 
         [0122]    In these two embodiments the proximal manipulator structure  2  has a convex, for example spherical, external surface two diametrically opposite portions of which constitute the opposite contact areas, the operator being able to apply his hand to the external surface of the structure. 
         [0123]    In  FIG. 13 , the convex structure is connected to the drive means  5  by a non-articulated connecting arm  2   g  the intermediate area  2   d  of which is elastically flexible and includes strain gauges  2   c.    
         [0124]    In  FIG. 14 , a peripheral sphere  2   h  can pivot about a central ball-joint  2   i  and movement sensors  2   c  determine movements of the peripheral sphere  2   h  around the central ball-joint  2   i  to generate the movement instructions. 
         [0125]    Consider next  FIGS. 15 to 19 , which show more specifically an advantageous embodiment of the distal controlled structure  3 . 
         [0126]    The object of this particular structure is to allow relative pivoting movements of large amplitude, possibly up to approximately 70° inclination on either side of the longitudinal axis I-I of the main arm  1 . 
         [0127]    Another object of the structure is to enable this pivoting by centered rotation, providing two degrees of freedom in pivoting about two intersecting transverse axes. In other words, the distal controlled structure  3  enables regular and precise inclination of a surgical tool  105   a  in all directions all around the longitudinal axis I-I of the main arm  1 . 
         [0128]    Another object of this structure is to enable simultaneously axial rotation of the surgical tool  105   a  on itself about its longitudinal axis, independently of the relative pivoting movements on either side of the longitudinal axis I-I of the main arm  1 . 
         [0129]    This provides three degrees of freedom that are independent of each other, namely two degrees of freedom in relative pivoting about intersecting transverse axes and one degree of freedom in axial rotation of the surgical tool  105   a  on itself. 
         [0130]    Moreover, the distal controlled structure  3  enables good proportionality of the movements of each of the three degrees of freedom relative to the corresponding stresses applied to the proximal manipulator structure  2 . 
         [0131]    In this embodiment shown in  FIGS. 15 to 19 , the distal controlled structure  3  includes, at the distal end  1   b  of the main arm  1 , a female articulation member  12  with a hemispherical distal cavity  13  and a male articulation member  14  in the form of a hollow hemispherical dome having a hemispherical external surface  14   a  and an interior void  14   b  wide open toward its base  14   c.    
         [0132]    The male articulation member  14  is engaged in the hemispherical distal cavity  13  of the female articulation member  12  with its interior void  14   b  oriented toward the hemispherical distal cavity  13 . 
         [0133]    An output shaft  15  is rotatably mounted in a radial bearing  16  of the male articulation element  14  and carries a tool  105   a  or a tool-holder  105   b.    
         [0134]    An input shaft  17  is rotatably mounted in an axial bearing  18  of the female articulation member  12  and is longitudinally engaged in the main arm  1 . 
         [0135]    A homokinetic transmission  19  connects the input shaft  17  to the output shaft  15  to transmit movements of axial rotation whilst allowing movements of transverse pivoting of the male articulation member  14  in the female articulation member  12 . 
         [0136]    In the embodiment shown in  FIG. 16 , the homokinetic transmission  19  includes a proximal universal joint  20  mounted at the interior end  17   a  of the input shaft  17 , a distal universal joint  21  mounted at the interior end  15   a  of the output shaft  15  and a telescopic transmission shaft  22  that connects the distal end universal joint  21  to the proximal universal joint  20 . The universal joints  20  and  21  are offset angularly by 90°, as shown in the figure, and are equidistant from the central axis of the spherical articulation consisting of the female articulation member  12  and the male articulation member  14 . 
         [0137]    Alternatively, the two universal joints ( 20 - 21 ) may be replaced by a tripod joint also providing homokinetic transmission. 
         [0138]    In the embodiment shown in this same  FIG. 16 , it is seen that the surgical tool  105   a  is a forceps with two jaws  105   c  and  105   d,  the jaw  105   d  being mobile about a transverse axis  105   e  to produce a clamping effect. 
         [0139]    In the embodiment shown, the mobile jaw  105   d  may be loaded by a traction cable, not shown, attached to a transverse arm  105   f  and passing through passages such as the passage  105   g  as far as the drive means, with a return spring  105   h  urging the mobile jaw  105   d  toward the spread apart position. 
         [0140]    Alternatively, a shape memory alloy tool  105   a  may be envisaged that can assume the clamped and open positions as a function of a temperature determined by a heat source controlled by the drive means. 
         [0141]    As seen in  FIGS. 17 to 19 , a plurality of control lines, such as the lines  23   a  and  23   b,  extend inside the main arm  1  and are engaged at the periphery of the hemispherical external surface  14   a  of the male articulation member  14 , to which peripheral surface they are fixed. 
         [0142]    At their other end, the control lines are mechanically coupled to the drive means  5  ( FIG. 8 ), which are themselves adapted to apply traction selectively to the control lines  23   a,    23   b.  The drive means  5  are supplied with power by an electronic control device which can advantageously include filter means or smoothing means for producing regular traction on the control lines  23   a  and  23   b  and thus prevent the transmission of any trembling of the operator. 
         [0143]    Where they enter the female articulation member  12 , the control lines such as the lines  23   a  and  23   b  pass through respective peripheral longitudinal guide passages  24   a  and  24   b  which guide them in order to guide axial rotation of the male articulation member  14 . The guide passages  24   a  and  24   b  are preferably as close as possible to the peripheral surface of the female articulation member  12 . On the male articulation member  14 , the control lines, such as the lines  23   a  and  23   b,  are engaged on the spherical surface of the male articulation member  14 . 
         [0144]    In practice, in the drive means  5 , the control lines  23   a  and  23   b  are loaded by linear actuators controlled by a control device. For example, the diametrally opposite control lines  23   a  and  23   b  may be coupled two-by-two with a proximal return pulley and with an actuator commanding the simultaneous translation of the two control lines  23   a  and  23   b  in opposite directions ( FIG. 18 ). 
         [0145]    In  FIG. 18 , the simultaneous movement in translation in opposite directions of the control lines  23   a  and  23   b  has brought about relative pivoting by approximately 45° of the male articulation member  14 . In  FIG. 19 , the relative pivoting has been accentuated, up to a maximum of about 70 degrees. 
         [0146]    The distal area of the main arm  1 , including the distal controlled structure  3 , may advantageously be enveloped by a flexible sheath, for example in a thin and flexible polymer, allowing the surgical tool to protrude. 
         [0147]    Consider next  FIGS. 20 to 22 , which show a particularly advantageous structure of a manipulator with surgical trocar  10 . 
         [0148]    The object of this structure is to reduce significantly the weight and the bulk of the manipulator itself by moving away the power supply means and the signal processing means. 
         [0149]    For this, the surgical trocar  10  is a tubular member including sliding contact means  10   b  electrically connected to external power supply and control means  200  including an electrical power supply and signal processing means. 
         [0150]    Thus the electrical conductors  200   a  include power conductors and signal conductors. 
         [0151]    The sliding contact means  10   b  are connected to a multiple conductive track  1   c  of the main arm  1 , which conductive track is connected on the one hand to the drive means  5  to supply electrical power to the drive means  5  and on the other hand to stress sensors  2   c  of the proximal manipulator structure  2 . 
         [0152]    The present invention is not limited to the embodiments explicitly described and includes variants and generalizations thereof within the scope of the following claims.