Patent Publication Number: US-2003233102-A1

Title: Active trocar

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to an active trocar for swinging a tube inserted in a hole, which is opened in an abdominal wall of a body on a surgical bed, around a vicinity of a center of the hole and advancing/retracting the tube.  
       [0003] 2. Description of the Related Art  
       [0004] In laparoscopic surgery, a small hole is opened in an abdominal wall of a patient body, and an instrument such as a forceps and an endoscope is inserted in the hole. Then, an operation such as excision and suture is performed in an abdominal cavity. This is an operation with a large burden for a surgeon because of difficulty in operating the instrument. Therefore, in recent years, a lot of technological developments have been made in a robot supporting the laparoscopic surgery.  
       [0005] In performance of the operation in the abdominal cavity, in order to obtain sufficient degrees of freedom at a tip of the instrument such as the forceps, it is desirable to secure six degrees of freedom with regard to a position and an orientation of the instrument in the abdominal cavity by means of both of the instrument and a mechanism for moving the instrument. FIG. 7 shows a motion of a forceps. As shown in the drawing, a forceps F is moved within a conical space CS having a point O as a center in the vicinity of a center of a hole AH in an abdominal wall of a patient body PB. Accordingly, the mechanism driving the forceps F generally has four degrees of freedom F1 to F4 shown by arrows in FIG. 7.  
       [0006] In a conventional method of driving a forceps, as shown in FIG. 8, an upper end of the forceps F is operated by a hand H of a robot such that the center O of swing (center of rotation) of the forceps F is located in the vicinity of the center of the hole AH in the abdominal wall. Such a robot needs to secure a wide operation range and high rigidity, as well as the robot realizes the same motion as human beings operate the forceps. Therefore, as shown in FIG. 9, the robot for driving a forceps was hitherto realized as a large-sized arm type (manipulator type) master-slave robot R.  
       [0007] However, the large-sized arm type robot R as described above occupies large space within an operating room, so that the robot prevents a doctor from accessing the patient at the time of emergency. Furthermore, because of a vicious circle of securement of rigidity of a long extending arm and an increase in power of an actuator moving the arm, the robot will increasingly become larger. Thus, downsizing of the robot driving an instrument such as the forceps while securing the rigidity is the largest requirement desired for the current surgery support robot.  
       [0008] Therefore, an object of the present invention is to provide an active trocar for swinging a tube inserted in a hole, which is opened in the abdominal wall of a body on a surgical bed, around a position of the hole as a center and advancing/retracting the tube, and for driving an instrument such as a forceps inserted through the tube as a small-sized surgery support robot. In the present invention, the robot and the instrument such as the forceps are unitized and actuators thereof are concentratedly located near the abdominal wall. Moreover, axes of three degrees of freedom, which are two axes of swing and an axis of linear movement, are allowed to intersect at one point in the vicinity of the center of the hole in the abdominal wall, so that the occupied range of space within the operating room is reduced while hardly reducing any degrees of freedom from that in the conventional one.  
       SUMMARY OF THE INVENTION  
       [0009] The active trocar of the present invention to advantageously solve the above described objects swings a tube inserted in a hole, which is opened in an abdominal wall of a body on a surgical bed, around a vicinity of a center of the hole and advances and retracts the tube. The active trocar includes a first parallel crank quadric chain, a second parallel crank quadric chain, a first swing drive means, a second swing drive means, and an advancement and retraction drive means. The first parallel crank quadric chain includes four links containing a base link, which is supported on a base to be swingable around a first swinging axis, the base being relatively fixed to the surgical bed. The four links are coupled to each other to be individually rotatable around rotating axes parallel to each other and orthogonal to the first swinging axis. Lines each connecting two rotating axes of the respective links form a parallelogram. The second parallel crank quadric chain includes four links containing two links respectively unitized with the link of said first parallel crank quadric chain rotatably coupled to the base link and the link in which a line connecting the two rotating axes is parallel to the line connecting the two rotating axes of the base link. The four links are coupled to each other to be individually rotatable around rotating axes parallel to each other and parallel to the rotating axis of said first parallel crank quadric chain. Lines each connecting two rotating axes of the respective links form a parallelogram. A support link among the remainder other than the foregoing two links in the four links, in which a line connecting the two rotating axes thereof intersects the line connecting the two rotating axes of the base link, is swung around a second swinging axis intersecting the first swinging axis at a right angle at a position spaced from the base link. Moreover, the support link supports the tube in such an orientation that a central axis of the tube passes an intersection point of the first swinging axis and the second swinging axis so as to be able to advance and retract the tube in an extending direction of the central axis of the tube. The first swing drive means swings the base link around the first swinging axis with respect to the base to swing the support link around the first swinging axis. The second swing drive means swings the link of the first parallel crank quadric chain rotatably coupled to the base link with respect to the base link to swing the support link around the second swinging axis. The advancement and retraction drive means advances and retracts the tube in the extending direction of the central axis of the tube with respect to the support link.  
       [0010] In the active trocar, the base is relatively fixed to the surgical bed such that an intersection point of the first swinging axis, the second swinging axis, and the central axis of the tube is located in the vicinity of the center of the hole opened in the abdominal wall of the body on the surgical bed. When an instrument such as the forceps is inserted through the tube, and then the first swing drive means, the second swing drive means, and the advancement and retraction drive means are properly operated, the first swing drive means swings, with respect to the base, the base link around the first swinging axis to swing the support link around the first swinging axis. Moreover, the second swing drive means swings, with respect to the base link, the link of the first parallel crank quadric chain rotatably coupled to the base link to swing the support link around the second swinging axis. Moreover, the advancement and retraction drive means advances and retracts the tube with respect to the support link in the extending direction of the central axis of the tube.  
       [0011] According to the active trocar of the present invention, an instrument inserted through the tube, which is supported by the support link so that the tube can be advanced and retracted in the extending direction of the central axis, can be swung around the first swinging axis and the second swinging axis, which pass an intersection point located in the vicinity of the center of the hole opened in the abdominal wall of the body on the surgical bed and are orthogonal to each other. Moreover, the instrument can be advanced and retracted in the extending direction of the central axis of the tube. Therefore, axes of three degrees of freedom, which are two axes of swing and one axis of linear movement, come to intersect at a point in the vicinity of the center of the hole in the abdominal wall. Furthermore, since the first swing drive means and the second swing drive means can be arranged in the vicinity of the base and the advancement and retraction drive means can be arranged in the vicinity of the support link, these drive means can be concentratedly arranged in the vicinity of the abdominal wall. Accordingly, a small-sized surgery support robot with high rigidity can be provided, in which the occupied range of space within the operating room is greatly reduced with hardly reducing any degrees of freedom from the conventional one. Moreover, since the axes of three degrees of freedom, which are two axes of swing and one axis of linear movement, intersect at the point in the vicinity of the center of the hole in the abdominal wall, the position and the orientation of the instrument can be changed without any burden on the abdomen of the patient.  
       [0012] The active trocar of the present invention may include a rotation drive means for rotating an instrument inserted through the tube around the central axis of the tube. With such a rotation drive means, a degree of freedom of rotation of the instrument around the central axis of the tube is added. Accordingly, a small-sized surgery support robot having four degrees of freedom equal to the conventional one can be provided, in which the occupied range of space within the operating room is greatly reduced. Moreover, the position and the orientation of the instrument can be changed with four degrees of freedom equal to the conventional one without any burden on the abdomen of the patient. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0013]FIG. 1 is a side view showing an example of an active trocar according to the present invention;  
     [0014]FIG. 2 is a side view showing an example of a structure for fixing the active trocar of the above example to a surgical bed;  
     [0015]FIG. 3 is a side view showing constitutions of a first parallel crank quadric chain and a second parallel crank quadric chain of the active trocar of the above example;  
     [0016]FIG. 4 is an explanatory view showing motion of the active trocar of the above example;  
     [0017]FIG. 5 is an explanatory view showing motion of the active trocar of the above example;  
     [0018]FIG. 6 is an explanatory view showing motion of the active trocar of the above example;  
     [0019]FIG. 7 is an explanatory view showing a motion of a forceps in laparoscopic surgery;  
     [0020]FIG. 8 is an explanatory view showing a conventional method for driving the forceps; and  
     [0021]FIG. 9 is an explanatory view showing a conventional robot for driving the forceps. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0022] Next, detailed description will be made for an embodiment of the present invention by use of an example with reference to the drawings. Here, FIG. 1 is a side view showing an example of an active trocar according to the present invention. FIG. 2 is a side view showing an example of a structure for fixing the active trocar of the example to a surgical bed. FIG. 3 is a side view showing constitutions of a first parallel crank quadric chain and a second parallel crank quadric chain of the active trocar of the example. Reference numeral  1  in the drawings denotes the active trocar in the example.  
     [0023] The active trocar  1  of the example includes a base  2  and a first parallel crank quadric chain  7 . FIG. 2 shows two active trocars of the example. The base  2  is supported by a typical articulated stand (passive positioner) ST, which is attached to a side of a surgical bed SB, to be fixed relatively to the surgical bed SB. The first parallel crank quadric chain  7  includes four links  3  to  6  containing a base link  3  supported on the base  2  so as to be able to swing around a first swinging axis O 1  as shown in FIG. 1. The four links  3  to  6  are coupled to each other with pivots  8  so as to be able to rotate around rotating axes O 3  to O 6 , which are parallel to each other and extended orthogonally to the first rotating axis O 1 , that is, in a direction orthogonal to the paper surface in FIG. 1. As shown in FIG. 3, lines L 1 , L 2 , L 3  and L 4  form a parallelogram. The line L 1  connects the two rotating axes O 3  and O 4  of the base link  3 . The line L 2  connects the two rotating axes O 3  and O 5  of the link  4  coupled to the base link  3 . The line L 3  connects the two rotating axes O 4  and O 6  of the link  5  also coupled to the base link  3 . The line L 4  connects the two rotating axes O 5  and O 6  of the link  6  coupled to the links  4  and  5 .  
     [0024] As shown in FIG. 1, the active trocar  1  of the example includes a second parallel crank quadric chain  11  including four links  4 ,  6 ,  9 , and  10 , containing two links which are respectively unitized with the link  4  of the first parallel crank quadric chain  7  rotatably connected to the base link  3  and the link  6  thereof where a line connecting two rotating axes thereof is parallel to the base link  3 . For convenience, these two links are indicated by the reference numerals  4  and  6  similar to the links  4  and  6  of the first parallel crank quadric chain  7 . The four links  4 ,  6 ,  9 , and  10  are coupled to each other with the pivots  8  so as to be able to rotate individually around rotating axes O 7  to O 9  and O 5 , which are parallel to the rotating axes O 3  to O 6  of the first parallel crank quadric chain  7  and parallel to each other. As shown in FIG. 3, lines L 5 , L 6 , L 7  and L 8  form a parallelogram. The line L 5  (part of the line L 5  is overlapped with the line L 4 .) connects the two rotating axes O 5  and O 7  of the link  6 . The line L 6  connects the two rotating axes O 5  and O 8  of the link  4 . The line L 7  connects the two rotating axes O 8  and O 9  of the link  9  coupled to the link  4 . The line L 8  connects two rotating axes O 7  and O 9  of the support link  10  coupled to the links  6  and  9 .  
     [0025] Here, as shown in FIG. 3, the support link  10  is arranged such that the line L 8  connecting the two rotating axes O 7  and O 9  of the support link  10  intersects the line L 1  connecting the two rotating axes O 3  and O 4  of the base link  3 . The support link  10  is thus swung around a second swinging axis O 2  by functions of the two parallel crank quadric chains  7  and  11  described above, wherein the second swinging axis O 2  intersects the first swinging axis O 1  at a position spaced from the base link  3 . Moreover, through a typical linear guiding mechanism  12 , the support link  10  supports an elevator  15 , to which a tube  13  and an instrument case  14  are attached, in such an orientation that a central axis OT of the tube  13  passes an intersection point of the first swinging axis O 1  and the second swinging axis O 2  so as to be able to advance and retract the elevator in an extending direction of the central axis OT of the tube  13 .  
     [0026] As shown in FIG. 1, the active trocar  1  of the example includes a typical geared motor  16  as a first swing drive means, a typical geared motor  17  as a second swing drive means, and a typical motor-drive linear movement mechanism  18  of a ball screw type as an advancement and retraction drive means. The geared motor  16  swings the base link  3  around the first swinging axis O 1  with respect to the base  2  to swing the support link  10  around the first swinging axis O 1 . The geared motor  17  swings the link  4  of the first parallel crank quadric chain  7 , the link  4  being rotatably coupled to the base link  3 , with respect to the base link  3  to swing the support link  10  around the second swinging axis O 2 . The linear movement mechanism  18  advances and retracts the tube  13  with respect to the support link  10  in an extending direction of the central axis OT of the tube  13 .  
     [0027] In addition, the active trocar  1  of the example, as shown in FIG. 1, includes an actuator  20  such as an electromagnetic solenoid and a typical geared motor  21  as a rotation drive means. The actuator  20  opens and closes a forceps tip  19   a  of an active forceps  19  accommodated in the instrument case  14 , the forceps tip  19   a  being projected from a tip of the tube  13 . The geared motor  21  rotates the forceps tip  19   a  around the central axis OT of the tube  13  to change the direction in which the forceps tip  19   a  is opened. The active forceps  19  itself is provided with a typical motor-drive linear movement mechanism of a ball screw type for tilting the forceps tip  19   a  with respect to the central axis OT of the tube  13 .  
     [0028] In the active trocar  1  according to the example, as shown in FIG. 2, the base  2  is fixed to the surgical bed SB by adjusting the articulated stand ST such that an intersection point P of the first swinging axis O 1 , the second swinging axis O 2 , and the central axis OT of the tube  13  is located in the vicinity of the center of the hole opened in the abdominal wall of the patient body PB laid on the surgical bed SB. When the forceps tip  19   a  of the forceps  19  is inserted through the tube  13 , and the geared motors  16  and  17  and the motor-drive linear movement mechanism  18  of a ball screw type are properly operated, the geared motor  16  swings the base link  3  around the first swinging axis O 1  with respect to the base  2  to swing the support link  10  around the first swinging axis O 1  as shown by an arrow A in FIG. 4. The geared motor  17  swings the link  4  of the first parallel crank quadric chain  7  rotatably coupled to the base link  3  with respect to the base link  3  as shown by an arrow B in FIG. 4 to swing the support link  10  around the second swinging axis O 2  as shown by an arrow C in FIG. 5. The motor-drive linear movement mechanism  18  of a ball screw type advances and retracts the tube  13  with respect to the support link  10  in the extending direction of the central axis OT of the tube  13  as shown by an arrow D in FIG. 6.  
     [0029] Furthermore, in the active trocar  1  of the example, the actuator  20  opens and closes the forceps tip  19   a  as shown in FIGS. 5 and 6. The geared motor  21  rotates the forceps tip  19   a  around the central axis OT of the tube  13  as shown by an arrow E in FIG. 6. The active forceps  19  itself tilts the forceps tip  19   a  with respect to the central axis OT of the tube  13  by means of the motor-drive linear movement mechanism of a ball screw type thereof.  
     [0030] According to the active trocar  1  of the example, the forceps tip  19   a  inserted through the tube  13 , which is supported by the support link  10  so that the tube can be advanced and retracted in the extending direction of the central axis TO, can be swung around the first swinging axis O 1  and the second swinging axis O 2 , which pass the intersection point P located in the vicinity of the center of the hole opened in the abdominal wall of the patient body PB on the surgical bed SB and are orthogonal to each other. Moreover, the forceps tip  19   a  can be advanced and retracted in the extending direction of the central axis OT of the tube  13 . Accordingly, axes of three degrees of freedom, which are two axes of swing and one axis of linear movement, come to intersect at the point P in the vicinity of the center of the hole in the abdominal wall. Furthermore, since the geared motors  16  and  17  can be arranged in the vicinity of the base  2  and the motor-drive linear movement mechanism  18  of a ball screw type can be arranged in the vicinity of the support link  10 , the geared motors  16  and  17 , and the motor-drive linear movement mechanism  18  can be concentratedly arranged in the vicinity of the abdominal wall. Therefore, as shown in FIG. 2, a small-sized surgery support robot with high rigidity can be provided, in which the occupied range of space within the operating room is greatly reduced compared with the conventional large-sized robot R with hardly reducing any degrees of freedom from that in the conventional one. Moreover, since the axes O 1 , O 2 , and OT of three degrees of freedom, which are two axes of swing and one axis of linear movement, intersect at the point P in the vicinity of the center of the hole in the abdominal wall as described above, the position and the orientation of the forceps tip  19   a  can be changed without any burden on the abdomen of the patient.  
     [0031] Furthermore, according to the active trocar  1  of the example, since the geared motor  21  for rotating the forceps  19   a  inserted through the tube  13  around the central axis OT of the tube  13  is provided, the degree of freedom of rotation of the forceps tip  19   a  around the central axis OT of the tube  13  is further added. Accordingly, a small-sized surgery support robot having four degrees of freedom equal to the conventional robot can be provided, in which the occupied range of space within the operating room is greatly reduced. Moreover, the position and the orientation of the forceps tip  19   a  can be changed with four degrees of freedom equal to the conventional robot without any burden on the abdomen of the patient.  
     [0032] According to the active trocar  1  of the example, the active trocar is provided with the actuator  20  for opening and closing the forceps tip  19   a,  and the active forceps  19  itself is provided with the typical motor-drive linear movement mechanism of a ball screw type for tilting the forceps tip  19   a  with respect to the central axis OT of the tube  3 . Accordingly, an operation of the forceps can be performed by remote control as a master-slave robot.  
     [0033] Hereinbefore, description has been made based on the example shown in the drawings. However, the present invention is not intended to be limited to the above described example. For example, the second parallel crank quadric chain may be constituted in such a manner that the link  5  is extended and rotatably coupled to the link  9 , and that the link  6  is rotatably coupled to only the links  5  and  10 . The shapes of the individual links may be properly changed according to need.  
     [0034] The articulated stand ST fixing the base  2  to the surgical bed SB may be supported by a support stood on a floor, not on the surgery bed. The instrument inserted in the tube  13  may be an endoscope or the like.