System and method for providing substantially stable control of a surgical tool

1. A system for providing substantially stable control of a surgical instrument, comprising:

a surgical manipulator for manipulating the surgical instrument; and

at least one computer configured to:

identify a first subset and a second subset of interaction geometric primitives associated with a virtual tool representing the surgical instrument;

determine, based on the first subset, control forces in a first subspace;

determine based on the second subset, control forces in a second subspace having at least one additional dimension to first subspace;

wherein control forces in the additional dimension are only determined based on the second subset of interaction geometric primitives, which is different than the first subset of interaction geometric primitives; and

determine a torque to constrain an orientation of the surgical instrument, wherein determining the torque comprises defining a virtual tool normal and a control plane normal and using the virtual tool normal and control plane normal to calculate the torque.

2. The system of claim 1 , wherein the first subspace has only one less dimension than the second subspace.

3. The system of claim 1 , wherein the first subspace is a two-dimensional subspace of three-dimensional space R 3 , and the second subspace is a three-dimensional subspace of three-dimensional space R 3 .

4. The system of claim 1 , wherein the at least one computer is configured such that a total interaction force is determined by summing at least the control forces in the first subspace and the control forces in the second subspace.

5. The system of claim 1 , wherein the interaction geometric primitives are at least one of a point, line, line segment, plane, circle, ellipse, triangle, polygon and curved arc segment.

6. The system of claim 1 , wherein the first subset includes a plurality of interaction geometric primitives.

7. The system of claim 6 , wherein the second subset includes only one interaction geometric primitive.

8. The system of claim 7 , wherein the interaction geometric primitive of the second subset is disposed between interaction geometric primitives of the first subset.

9. The system of claim 1 , wherein the first subset constitutes a non-linear boundary of the virtual tool.

10. The system of claim 1 , wherein the at least one computer is configured to determine a torque based at least in part on an orientation of the virtual tool.

11. The system of claim 1 , wherein the computer is further configured to selectively operate the surgical manipulator in a first operating mode and a second operating mode.

12. The system of claim 11 , wherein the first operating mode is a manual mode and the second operating mode is a semi-autonomous mode.

13. A method for providing substantially stable control of a surgical instrument, comprising:

identifying a first subset and a second subset of interaction geometric primitives associated with a virtual tool representing a surgical instrument:

determining based on the first subset, by at least one computer, control forces in a first subspace;

determining based on the second subset, by at least one computer, control forces in a second subspace having at least one additional dimension to the first subspace;

wherein control forces in the additional dimension are only determined based on the second subset of interaction geometric primitives, which is different than the first subset of interaction geometric primitives; and

determining a torque to constrain an orientation of the surgical instrument, wherein determining the torque comprises defining a virtual tool normal and a control plane normal and using the virtual tool normal and control plane normal to calculate the torque.

14. The method of claim 13 , wherein the first subspace has only one less dimension than the second subspace.

15. The method of claim 13 , wherein the first subspace is a two-dimensional subspace of three-dimensional space R 3 , and the second subspace is a three-dimensional subspace of three-dimensional space R 3 .

16. The method of claim 13 , further comprising:

determining, by at least one computer, a total interaction force by summing at least the control forces in the first subspace and the control forces in the second subspace.

17. The method of claim 13 , wherein the interaction geometric primitives are at least one of a point, line, line segment, plane, circle, ellipse, triangle, polygon and curved arc segment.

18. The method of claim 13 , wherein the first subset includes a plurality of interaction geometric primitives.

19. The method of claim 13 , wherein the second subset includes only one interaction geometric primitive.

20. The method of claim 19 , wherein the interaction geometric primitive of the second subset is disposed between interaction geometric primitives of the first subset.

21. The method of claim 13 , wherein the first subset constitutes a non-linear boundary of the virtual tool.

22. The method of claim 13 , further comprising:

determining a torque based at least in part on an orientation of the virtual tool.