Abstract:
The present invention discloses a system for handling a surgical instrument, useful for observation and/or intervention with respect to a patient&#39;s body. The system comprising a fixed support; hinge which enable changing of the inclination of the system; actuators system that produce the rotation movement utilized by handling surgical instrument mechanism; a flexible power transmission system; gear housing adapted to change the direction of the motors rotation transmitted by the flexible power transmission system; and, handling surgical instrument mechanism, said mechanism comprising: a first small size moveable element, connected to the gear housing is adapted to simultaneous maneuver of a second moveable element to the four main directions, and/or any other maneuver, e.g., right and left, forward and backward; and, a second moveable element that which is adapted to move the surgical instrument to another directions, zoom in and zoom out, simultaneously rotate the surgical instrument, either clockwise or counter-clockwise, simultaneously rotate the camera housing in respect to the surgical instrument clockwise and counter-clockwise.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International Application No. PCT/IL2008/000902, filed Jul. 1, 2008, which claims the benefit of priority of U.S. Provisional Patent Application No. 60/929,528, filed 2 Jul. 2007. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to means and method of manipulating an endoscope system for laparoscopic surgery, in which the endoscope is inserted through a small incision into the patient body&#39;s cavities. 
     BACKGROUND OF THE INVENTION 
     In laparoscopic surgery, the surgeon performs the operation through small holes using long instruments and observing the internal anatomy with an endoscope camera. The endoscope is conventionally held by a camera assistant since the surgeon must perform the operation using both hands. 
     The surgeon performance is largely dependent on the camera position relative to the instruments and on a stable image shown at the monitor. 
     The main problem is the difficulty for the assistant to hold the endoscope steadily, keeping the scene upright 
     To overcome these problems, several new technologies have been developed, also using robotics to hold the endoscope while the surgeon performs the procedure. Most known of them are Lapman™, EndoAssist™, and Aesop™. 
     But these technologies are expensive, difficulty installed, uncomfortable to use, limiting the dexterity of the surgeon and having physical dimension much bigger that all operating tools. 
     Relatively to the required action, they also move in big bounds with several arms movement. The patents of these products are presented in  FIGS. 23   a ,  23   b , and  23   c.    
     SUMMARY OF THE INVENTION 
     It is therefore one object of the present invention to present a novel system for handling a surgical instrument, useful for observation and/or intervention with respect to a patient&#39;s body; said system comprising a fixed support; hinge which enable changing of the inclination of the system; actuators system that produce the rotation movement utilized by handling surgical instrument mechanism; a flexible power transmission system; gear housing adapted to change the direction of the motors rotation transmitted by the flexible power transmission system; and, handling surgical instrument mechanism, said mechanism comprising: a first small size moveable element, connected to the gear housing is adapted to simultaneous maneuver of a second moveable element to the four main directions, and/or any other maneuver, e.g., right and left, forward and backward; and, a second moveable element that which is adapted to move the surgical instrument to another directions, zoom in and zoom out, simultaneously rotate the surgical instrument, either clockwise or counter-clockwise, simultaneously rotate the camera housing in respect to the surgical instrument clockwise and counter-clockwise. 
     The flexible power transmission system is possibly comprised of a plurality of tubes interconnected via a plurality of joints, adapted to rotate to and to keep any desired angle. The tubes possibly contain shafts that transmit the actuators rotation to said gear housing. The gear housing possibly comprises of a plurality of gear transmissions that may move simultaneous the moveable parts of the handling surgical instrument mechanism. The power transmission to the second moveable part of handling surgical instrument mechanism is possibly transferred via flexible means. The gears transmission possibly transfers the power to moveable parts of said first said second moveable element via clutches that stops said power transmission at a desired threshold. The clutches possibly allows the surgeon to move the surgical instrument by without the need to disconnect the surgical instrument from the handling surgical instrument. The first small size moveable element is possibly having a spatial structure, wherein the element contains a pushing and pulling mechanism to produce the forward backward movement of the surgical instrument. The first small size moveable element is possibly connected to a gear transmission of the gear housing that rotates the first moveable element in the right and left directions. The first small size moveable element is possibly having a gimbals&#39; connection to the surgical instrument, insulating the patient body from the handling surgical instrument mechanism. The second small size moveable element is possibly having a linear connection to first small size moveable element. The second small size moveable element is possibly having a gear housing allowing the transfer of the rotation power supplied by said flexible means to produce movements of the surgical instrument in desired directions. The second small size moveable element is possibly having a gear housing allowing the transfer of the rotation power supplied by the flexible means to produce a linear movement of the surgical instrument. The second small size moveable element is possibly having a gear housing allowing the transfer of the rotation power supplied by the flexible means to produce rotation movement of the surgical instrument. The second small size moveable element is possibly having a gear housing allowing the transfer of the rotation power supplied by the flexible means to produce rotation movement of the camera with respect to the surgical instrument. The second small size moveable element is possibly having a quick release mechanism enabling fast removal and fast installation of the surgical instrument. The second small size moveable element is possibly having an adopter allowing using various of surgical instruments. The system is possibly having a structure that has small presence above and near the patient body without distracting the surgeon activities. The handling surgical instrument mechanism is possibly having a structure and mechanism that may be manufactured from inexpensive materials. A disposable handling surgical instrument mechanism is also disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows the use of the use of the present invention while performing a laparoscopic procedure in the operating room; 
         FIG. 2  shows the robotic camera holder attached to the operating table; 
         FIG. 3  presents the 5 degrees of freedom of the robotic arm; 
         FIG. 4  shows the robotic arm locked in robotic mechanism housing; 
         FIG. 5   a  shows the main parts of the robotic arm; 
         FIG. 5   b  shows the inside mechanism of the robotic arm; 
         FIG. 5   c  shows in perspective view the inside mechanism of the robotic arm; 
         FIG. 6  shows in perspective view the The DF  3 ,  4 ,  5  components; 
         FIG. 7  shows in perspective view the endoscope  7  held by component  1200 ; 
         FIG. 8   a  shows the zoom mechanism and parts; 
         FIG. 8   b  shows the zoom in almost its lowest position; 
         FIG. 8   c  the screw as a outer thread; 
         FIG. 8   d  shows part of the zoom mechanism; 
         FIG. 8   e  shows the worm gear that transmits the rotation to the screws of the gear mechanism; 
         FIGS. 9   a  and  9   b  show the mechanism that rotates endoscope; 
         FIG. 9   b  shows the endoscope housing; 
         FIGS. 10   a - 10   c  show a lock mechanism that holds the endoscope from being pulled out from its position; 
         FIG. 11   a  to  FIG. 11   f  shows the mechanism that moves the camera head; 
         FIG. 12  shows the main components of the robot; 
         FIG. 13  shows the motors box; 
         FIG. 14  shows the driving system setup; 
         FIG. 15  show another view of connection between the motor gear and the shaft; 
         FIGS. 16   a - 16   e  show the power transmission system; 
         FIG. 17  shows the robotic arm housing; 
         FIG. 18  shows the gear housing in front view with it&#39;s cover removed exposing the gears that transmits the motors to the robotic different arm mechanisms; 
         FIG. 19  shows in closer view the mechanisms in housing; 
         FIG. 20  shows from another angle the inner mechanism of housing; 
         FIG. 21  shows the clutch mechanism that may protect the patient body from being hurt; 
         FIG. 22  shows the clutch mechanism that may protect the patient body from being hurt; 
         FIGS. 23   a ,  23   b ,  23   c  show prior art patents. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present invention discloses inter alia means for controlling the spatial position of endoscope tube in laparoscopic surgery. The present device is cheap, easily install and disassemble, comfortable to use, not limiting the dexterity of the surgeon and having small physical dimension. 
     The small size of present invention is achieved by:
         1. the shape of the main arm;   2. separating the moving parts from the motors and transmitting the motor power by shafts and cable means;   3. a linear zoom mechanism, allowing a full range zoom action, independent of other moving parts in the mechanism;   4. a rotational mechanism that rotates the endoscope about it&#39;s long axis, independently of other moving parts of the mechanism;   5. another rotational mechanism that rotates the digital camera attached to the endoscope about it&#39;s long axis, independently of the endoscope and other moving parts of the mechanism       

     The inexpensive price of the present invention is achieved by
         1. the small physical dimension of the present invention;   2. the simplicity of the mechanisms of the present invention;   3. the material that may be used to produce the body and the mechanisms of the present invention.       

     The easy installation and disassemble processes is achieved by
         1. the small physical dimension of the present invention;   2. the safety mechanisms of the present invention;   3. the movement compensation mechanisms of the present invention;   4. the separation between the moving parts that are near patient&#39;s body from the relatively motors box that is located away from the patient, under the operating table;   5. the flexible structure of the power transmission system that connects the motors box to the moving parts.       

       FIG. 1  shows the use of the present invention while performing a laparoscopic procedure in the operating room. The patient  2  is laid on the operating table  3 . The surgeon  1  is performing the procedure using the laparoscopic tools  4  and  5  the robotic camera holder  100  is attached to the operating table rails  6  and positioned near the surgeon, holding the endoscope  7  that is inserted to the body of the patient  2 . 
       FIG. 2  shows the robotic camera holder  300  attached to the operating table  3 . The RCH is inserted to the adapter  10 , which is connected to rails  6 . the components of the RCH are shown: motor box  110 , power transmission system  120  the robotic arm  1100  and the robotic arm housing  200  the endoscope  7  is inserted to the patient body  2  the camera  8  is attached to the distal end of the endoscope  7 . 
     The endoscope is inserted through a tiny incision in the patient body. 
     In a free state the endoscope  7 , as a rigid body, has 6 degrees of freedom. 
     The incision eliminates 2 DF of the endoscope by not allowing one end of the endoscope to move in 2 main directions. In order to have a fully defined position of the endoscope a mechanism with 4 degrees of freedom is needed. 
       FIG. 3  presents the 5 degrees of freedom of the robotic arm. 
     DF 1  presents the ability of the robot to move the endoscope  8  to the right and left with respect to the robotic mechanism housing.  200   
     DF 2  presents the ability of the robot to move the endoscope forward and backward with respect to the robotic mechanism housing. 
     DF 3  presents the ability of the robot to move the endoscope in a zoom movement, i.e in and out of the patient body through the penetration point. 
     DF 4  presents the ability of the robot to rotate the endoscope about its long axis. This degree of freedom is necessary when using endoscope with “angled” edge. 
     DF 5  presents the ability of the robot to rotate the camera  8  with respect to the endoscope&#39;s long axis. This degree of freedom is necessary to keep the horizon of the image when using endoscope with “angled edge. 
       FIG. 4  shows the robotic mechanism  1000  locked in robotic mechanism housing  200 . the RCH  1000  consist of two main components: the robotic arm that moves the endoscope in the direction of DF 1  and DF 2 . Component  1200  moves the endoscope in the direction of DF  3  DF 4  and DF 5 . 
     The robotic arm  1100  will be described in details at  FIGS. 5   a ,  5   b ,  5   c.    
       FIG. 5   a  shows the main parts of the robotic arm  1100 . The body of the robotic arm consists of two arced shape elements  1101  and  1102 . the robotic arm moves in the direction of DF 1 , from side to side. The robotic arm includes an inside mechanism that moves a chain that pulls (backward) and pushes (forward) component  1200  in the direction of DF 2 . A part of this chain  1110  is shown partly through slot  1109 . 
       FIG. 5   b  shows the inside mechanism of the robotic arm. In the arced shape  1101   a  of part  1101  the arced slot  1104  contains the chain  1110  that adapts it&#39;s shape to the curved slot  1104 . the nut  1130  moves forward and backward according to the rotation of screw  1140  placed in slot  1142 . The nut  1130  is connected to chain  1110  via pin  1106 . When the nut moves backward it pulls chain  1110  into the linear slot  1105 , performing the forward movement of DF 2 . When the nut moves forward it pushes chain  1110  out the linear slot  1105 , performing the backward movement of DF 2 . 
     Component  1200  is attached to the robotic through a connecting pin placed in hole  1120  at the first link of the chain. 
       FIG. 5   c  shows in perspective view the inside mechanism of the robotic arm. 
       FIG. 6  shows in perspective view the The DF 3 , 4 , 5  component  1200 . component  1200  moves the endoscope in a linear motion DF 3   1220 , and two rotation movement: DF 4  that rotates the endoscope about the endoscope&#39;s long axis. This movement is done by mechanism  1240  and DF 5  that rotates the camera with respect to the endoscope&#39;s long axis, by mechanism  1270 . Component  1200  is connected to the robot arm  1100  via pin  1201 . 
       FIG. 7  shows in perspective view the endoscope  7  held by component  1200 . and the relations between the different degrees of freedom of the mechanisms. The endoscope  7  is held by housing  1241  that rotates in the direction of DF 4  and the camera  8  is held by housing  1271  that moves in the direction of DF 5 . these independent motions enables the control of angled endoscope to achieve a desired view for the surgeon, while maintaining the horizon position when rotating the camera  8  in the direction of DF 5 . The optic fibers cable  9  that transmits the light to the optic fibres of the endoscope, is shown with relation to the top part  1221  of the zoom component  1220 , demonstrating the ability of the endoscope  7 , to rotate, if needed a complete circle with no interference. The endoscope passes through the gimbal  1210  into the trocar (not shown) 
       FIG. 8   a  shows the zoom mechanism and parts. The zoom mechanism in principle consists of chain of screws. One of the screws is fixed with respect to the other screws. The other screws serve also as a nut. All screws have the same pitch, so any of the screws that are being screwed, do not change the rate of change of the height of the zoom. 
     A typical screw  1223  is shown in  FIG. 8   c  the screw as a outer thread  1223   a  and a inner thread  1223   b.    
       FIG. 8   d  shows part of the zoom mechanism. The fixed screw  1224  that has only outer thread is shown screwed in the inner thread of screw  1223   a.    
       FIG. 8   e  shows the worm gear that transmits the rotation to the screws of the gear mechanism. When shat  1261  is being rotated the cylinder of the worm gear rotates and rotates gear  1263  that is coupled to the head of crew  1221  the rotation movement of screw  1221  rotates one or more screws in the chain, the zoom height changes according to the screw  1263  direction of rotation. 
       FIG. 8   b  shows the zoom in almost its lowest position. The screws are contained in cylinder  1225  cylinder  1225  is connected to gimbal  1210  via pin  1226  that does not allow cylinder  1225  to move or rotate. Cylinder  1225  serves also as the fixed point for screw  1224  that is connected rigidly to it&#39;s center. 
       FIGS. 9   a  and  9   b  show the mechanism that rotates endoscope  7  in the direction of DF 4 . The gear that rotates the endoscope is located in gearbox  1260  shown in  FIG. 9   a . The worm gear  1265  located on shaft  1264  transmits the rotation to the gear  1266 . The endoscope  7  passes through hole  1266   a  and rotates with the gear  1266  as will be explained in  FIG. 9   b.    
       FIG. 9   b  shows the endoscope housing  1270  housing  1240  has three arms  1240   a,b,c  that hold the mechanism that moves camera  8  in the direction of DF 5 . the arms  1240  arises from structure  1241  that contains in the squared hole  1241   a  the head  7   a  of the endoscope, and in semi circular hole  1241   b  the endoscope&#39;s optic fiber connection  7   b . the quick release extension  1241   c  is inserted into gear  1266  and the pin  1241   d  (not shown) located at the bottom of housing  1241  is inserted into hole  1266   a  forcing housing  1241  to rotate together with gear  1266 . 
     The pin and hole structure is used to keep the orientation of the endoscope when the endoscope is re inserted after it was pulled out of the mechanism. 
       FIGS. 10   a - 10   c  show a lock mechanism that holds the endoscope from being pulled out from it&#39;s position. The locker arm  1242  is connected to arm  1240   b  and rotates freely about it. In order to lock the endoscope in its position the locker arm is rotated to the position shown in  FIG. 10   b . In order to keep the locker arm in its place, the locker arm has notch  1242   b  in it&#39;s free side. Also the locker arm has a curved part  1242   a  that fits the endoscope body. 
       FIG. 11   a  to  FIG. 11   f  shows the mechanism  1270  that moves the camera head  8  in the direction of DF 5  the mechanism  1270  is adopted on the top mechanism  1240 : arms  1240   a  and  1240   b  passes through holes in arms  1277   a  and  1277   b.    
       FIG. 11   a  show a general perspective view of the main parts of mechanism  1270 . Housing  1271  contains gear  1273  that rotates camera head  8 . Camera head  8  is fixed in gear  1273  by adapting ring  1272 . As shown in  FIG. 11   c , adapting ring  1272  is a split so it can be fitted to various sizes of camera heads. In order to insure a tight fixation of ring  1272  to camera head  8 , screw  1275  is used as shown in  FIG. 11   b .  FIG. 11   c  also shows the pin  1276   a  arises from ring  1272 . When fixing camera head  8  into gear  1273  pin  1276   a  is fixed in notch  1276   b  shown in  FIG. 11   d . This mechanism insures that camera head  8  will move together with gear  1273  with out any slip. Another task of this mechanism, when removing the endoscope with camera head (in order to clean the endoscope for example) is to maintain the orientation of camera head  8  with respect to gear  1273  when fixing the endoscope back to it&#39;s position. 
       FIG. 11   e  shows the gear transmission of mechanism  1270 . Axis  1277   b  arises from arm  1240   c  (shown in  FIG. 9   b .) is connected to gear  1282  and gear  1285 . the gear house  1280  contains vertical gear  1283 . when the vertical gear  1283  is rotated by axis  1281 , it transmit the rotation through gear  1283  and gear  1285  to gear  1273  and to the adapting ring  1272  which holds the endoscope and rotates it. 
       FIG. 11   f  shows the two independent degrees of freedom DF 4  and DF 5 . The orientation of the camera (shown in white doted line) is different from the orientation of the endoscope (shown in black doted line). 
       FIG. 12  shows the main components of the robot: component  100  is the robot arm mechanism that holds the robot and moves it in the direction of it&#39;s five independent degrees of freedom. components  200 , 300 , 400  creates the power that drives the robotic arm mechanism. 
     Component  400  includes the motors that produce the driving power. 
     Component  300  is a contraction that transfers the motor power to the part  200 . 
     Component  200  is a gear box that transfers the direction of the rotation axis, while changing the transmission ratio. Component  200  serves also as the housing of component  100 . 
       FIG. 13  shows component  400  of the system in details. Component  400  includes motors box  401  with adaptor  402  that connects component to component  300 . 
     The driving system (motors, gears Etc.) is fixed to the motor box. 
       FIG. 14  shows the driving system setup. The driving system includes motors, gear transmissions attached to the motors and transmission means that connects the motors&#39; gear boxes to the shafts in that drive the motors&#39; power through component  300 . 
     A simple setup includes motor such as  410 ,  420 , gearbox attached to the motor  411 , 421 , gear mountained on the output shaft of the gear box  412 , 422 , transmission means to component  300  shaft, seen here as belts  413  and  414 . Belts  413  and  423  transmits power to gears  414  and  424  fixed to component&#39;s  300  shafts. 
     Of course there may other ways of designing another kinds of small effective motor box with the same performance. 
       FIG. 15  show another view of connection between the motor gear  411  and the shaft  311 . while belt  413  rotates it rotates also gear  14  that is fixed to shaft  311 . 
       FIG. 16   a  shows the power transmission system  300 . The power transmission system consists of pipe structure that connect the motor box  400  to the robotic arm  200 . 
     The lower pipe  320  is vertical an is connected to pipe  300  by joint  350 . pipe  300  may be positioned in various angles with respect to the vertical pipe  320 . another joint  360  may be used for positioning the upper part of the joint  365 , which is connected to the robotic arm housing  200 . Joint  350  and  360  angle are changed by rotating screws  351  and  361  respectively. The power produced in the motor box is transmitted to the robotic arm by shafts placed in the pipes. In order to be able to bend the joints of the pipe structure a cardan joints ( 354  and  364  for example) are used. Flexible shafts may be used also to transmit the motors rotation to housing  200 . 
       FIG. 16   b . shows the power transmission system  300 . Pipes  320  and  330  are shown in transparent, shaft  321  and shaft  331  may be seen. 
       FIG. 16   c  shows power transmission system  300  in perspective view. In order to simplify the explanation will refer to only one shaft. The bottom end of shaft  311  arises from the bottom of pipe  320 . The upper end of shaft  311   u  is connected to the next shaft bottom  321   b , with a Cardan joint  354 . Shaft  321  upper end  321   u , is connected to Cardan joint  364  transmitting the motor rotation into the upper end  359  of joint  360 . 
       FIG. 16   d  shows in details the structure of joint  350 . Joint  350  allows the surgeon to position the robotic camera arm in a favor position, without interfering the transmission of power from motor box  400  to the arm housing  200 . Arm  355   a  is connected rigidly to housing  355 . Arm  353  is connected rigidly to housing  352 . Arm  353  and  355   a  are connected with pivot  358 . Cardans  354  with their axis aligned with the center of pivot  358 , allowing the joint to bend freely. The surgeon may bend the joint by rotating the screw  351   
       FIG. 16   e  shows another view of joint  350 . The upper side  369  is shown in transparent and the upper part  321   u  of shaft  321  is shown. 
       FIG. 17  shows the robotic arm housing  200 . Housing  200  is attached on top of joint  350  in adapter  369  that contains the ends of shafts  321 ,  322 ,  323  etc. housing  200  has a cover  240 . 
     Tubes  210 ,  211 ,  212  are rising from the back of housing  200 . As will be described later these tubes contain flexible shafts that transmit rotation movement to component  1200  of the robotic arm  1000 . The back of housing  200  contains also adapter  230  that holds shaft  1150  of component  1100  of robotic arm  1000 . Shaft  1150  is secured in hole  231 . 
       FIG. 18  shows housing  200  in front view with cover  240  removed exposing the gears that transmits the motors to the robotic different arm mechanisms. In the front  201  of housing  200 , cylinder  220  with recess  221  is seen. Cylinder  220  rotates the robotic arm  1100  in direction of DF 1 . The back of robotic arm  1100  is secured into recess  221  and shaft  1150  pass through holes  222  and  223  to the back  202  of housing  200 . Shaft  321  rotates worm gear  253  that rotates gear  251  that rotates cylinder  220 . Shafts  322  and  323  and  324  (not seen) transmits their rotation, as will be described later, to shafts  261 ,  262  and  263 . Shafts  261 ,  262  and  263  rotate the flexible shafts  213 ,  214  and  215  respectively. The ends of flexible shafts arises from flexible tubes  210 ,  211  and  212 . 
       FIG. 19  shows in closer view the mechanisms in housing  200 . The rotation of the robotic arm from side to side, in the direction of DF 1  is achieved by rotating gear  251  by worm  253  attached to vertical shaft  321 . The rotation of screw  1140  that enables the movement of the endoscope forward and backward in respect to the robotic arm is achieved by restating gear  223  by vertical gear  224  which is attached to shaft  323 . Gear  223  rotates screw  1140  via clutch located in housing  231 . 
     The principle of the transmission of the rotation to the flexible shafts remains the same for all of the flexible shafts: the horizontal gear  331  rotates vertical gear  271 . Gear  271  is attached to shaft  261 . Shaft  261  is connected to flexible shaft  213  which is located in flexible tube  210  that directs flexible shaft  213  upward to it&#39;s connection with mechanism  1000 . 
       FIG. 20  shows from another angle the inner mechanism of housing  200 . 
     Housing  200  is shown in transparent and the gear transmission between the horizontal gears  331 ,  332  and  333  and the vertical gears  272 ,  272  and  273  respectively is demonstrated. The ends of shafts  321 ,  322  and  323  are shown. This structure enables quick disassembling for simple maintenance and to use different kinds of housings for that activates different robotic mechanisms with the same motors no need to release from the operating table, the other main parts of the robotic system. 
       FIG. 21  shows the clutch mechanism that may protect the patient body from being hurt by an allowed forces applied by the robotic arm. In this example the clutch consists of two magnets  256  and  257  that attached to each other by their magnetic force. Magnet  256  is attached rigidly to gear  251  and magnet  256  is attached rigidly to the robotic arm housing  220 . While rotating the robotic arm in the direction of DF 1 , if the force applied by the endoscope on the patient body exceeds a threshold level, the magnets slides on each other and the robotic arm stops moving in the direction of DF 1 . The magnets may be changed in respect to nature of the surgery or to the patient properties: fat or thin patient, infant or adult. 
       FIG. 22  shows the clutch mechanism that may protect the patient body from being hurt by an allowed forces applied by the robotic arm. In this example the clutch consists of two magnets  233  and  234  that attached to each other by their magnetic force. Magnet  234  is attached rigidly to gear  223  (not shown) and magnet  233  is attached rigidly to the robotic screw  1140  (not shown). While moving the endoscope forward and backward in the direction of DF 2 , if the force applied by the endoscope on the patient body exceeds a threshold level, the magnets slides on each other and the endoscope movement in the direction of DF 1  stops. The magnets may be changed in respect to nature of the surgery or to the patient properties: fat or thin patient, infant or adult. 
       FIGS. 23   a ,  23   b ,  23   c  shows prior art patents