Offset remote center manipulator for robotic surgery

1. A manipulator for constraining a position of a surgical instrument, the manipulator comprising:

a mounting base;

a parallelogram linkage base having a proximal end and a distal end, the parallelogram linkage base proximal end coupled to the mounting base, the parallelogram linkage base proximal end rotatable relative to the mounting base about a first axis, the parallelogram linkage base distal end lying on an axis offset from the first axis;

a first link having a proximal end and a distal end, the first link proximal end coupled to the parallelogram linkage base distal end;

a second link having a proximal end and a distal end, the second link proximal end coupled to the first link distal end, the second link constrained from rotating relative to the parallelogram linkage base; and

an instrument holder coupled to the second link distal end, the instrument holder constrained from rotating relative to the first link, the instrument holder configured to support a surgical instrument for extension along a longitudinal axis of the surgical instrument.

2. The manipulator of claim 1 , further comprising a base support, the mounting base fixably coupled to the base support.

3. The manipulator of claim 1 , the parallelogram linkage base being on a plane offset from the first and second links.

4. The manipulator of claim 1 , further comprising a brake system releasably inhibiting rotation about at least one of:

a joint coupling the mounting base to the parallelogram linkage base;

a joint coupling the first link to the parallelogram linkage base; and a joint coupling the second link to the first link.

5. The manipulator of claim 1 , the second link constrained from rotating relative to the parallelogram linkage base by flexible elements running on two pulleys, one pulley being fixed to the parallelogram linkage base and one pulley being fixed to the second link.

6. The manipulator of claim 1 , the instrument holder constrained from rotating relative to the first link by flexible elements running on:

one pulley fixed to the first link; and

one pulley fixed to the instrument holder.

7. The manipulator of claim 1 , the second link comprising a main bent link bent at an angle, the main bent link providing clearance for the first link to rest on the main bent link.

8. The manipulator of claim 7 , the instrument holder constrained from rotating relative to the first link by flexible elements running on:

one pulley fixed to the first link;

one pulley fixed to the instrument holder; and idler pulleys for directing the flexible elements around the main bent link.

9. The manipulator of claim 1 , the first and second links offset in different planes.

10. The manipulator of claim 1 , further comprising motors for driving movement about the first axis, the motors housed in the mounting base.

11. A manipulator for constraining a position of a surgical instrument, the manipulator comprising:

an articulate linkage assembly having a mounting base rotationally coupled to a parallelogram linkage base for rotation about a first axis, the parallelogram linkage base coupled to the instrument holder by a parallelogram means for constraining the elongate shaft of the instrument relative to a center of rotation when the instrument is mounted to the instrument holder and the shaft is moved in at least one degree of freedom, wherein the first axis and a first side of the parallelogram means adjacent the parallelogram linkage base intersect the shaft at the center of rotation, and the first side of the parallelogram means is angularly offset from the first axis.

12. A method for constraining a position of a surgical instrument, the method comprising:

rotating a parallelogram linkage base relative to a mounting base about a first axis, the parallelogram linkage base having a proximal end coupled to the mounting base and a distal end lying on an axis offset from the first axis;

rotating a first link relative to the parallelogram linkage base, the first link coupled to the distal end of the parallelogram linkage base at a first joint;

rotating a second link relative to the first link, the second link coupled to the first joint at a second joint;

extending an instrument holder supporting the surgical instrument along a longitudinal axis, the instrument holder coupled to the second link;

constraining rotation of the second link relative to the parallelogram linkage base; and

constraining rotation of the instrument holder relative to the first link.

13. The method of claim 12 , the mounting base fixably coupled to a base support.

14. The method of claim 12 , the parallelogram linkage base being on a plane offset from the first and second links.

15. The method of claim 12 , further comprising releasably inhibiting rotation about at least one of:

a joint coupling the mounting base to the parallelogram linkage base;

the first joint; and

the second joint.

16. The method of claim 12 , the second link constrained from rotating relative to the parallelogram linkage base by flexible elements running on two pulleys, one pulley being fixed to the parallelogram linkage base and one pulley being fixed to the second link.

17. The method of claim 12 , the instrument holder constrained from rotating relative to the first link by flexible elements running on:

one pulley fixed to the first link; and

one pulley fixed to the instrument holder.

18. The method of claim 12 , the second link comprising a main bent link bent at an angle, the main bent link providing clearance for the first link to rest on the main bent link.

19. The method of claim 18 , the instrument holder constrained from rotating relative to the first link by flexible elements running on:

one pulley fixed to the first link;one pulley fixed to the instrument holder; and

idler pulleys for directing the flexible elements around the main bent link.

20. The method of claim 18 , the first and second links offset in different planes.

21. The method of claim 18 , further comprising motors for driving movement about the first axis, the motors housed in the mounting base.

22. A method for performing minimally invasive robotic surgery within a body cavity of a patient employing a surgical instrument coupled to an instrument holder, the instrument including an elongate shaft, the shaft having a distal working end configured for insertion through an incision in a body wall into the body cavity, the method comprising:

providing an articulate linkage assembly having a mounting base rotationally coupled to a parallelogram linkage base for rotation about a first axis, the parallelogram linkage base coupled to the instrument holder by a plurality of links and joints, the links and joints defining a parallelogram so as to constrain the elongate shaft of the instrument relative to a center of rotation when the instrument is mounted to the instrument holder and the shaft is moved in at least one degree of freedom, wherein the first axis and a first side of the parallelogram adjacent the parallelogram linkage base intersect the shaft at the center of rotation, and the first side of the parallelogram is angularly offset from the first axis;

coupling the instrument to the instrument holder; introducing at least the distal working end of the instrument shaft through the incision into the body cavity; and

pivotally moving at least the shaft of the instrument in at least one degree of freedom while at least a portion of the distal working end is within the body cavity and while the offset articulate linkage assembly constrains lateral motion of the shaft to pivotal motion about the center of rotation so that the shaft is maintained substantially aligned through the center of rotation.