Surgical robotic system and method for commanding instrument position based on iterative boundary evaluation

1. A system comprising:

a surgical instrument including an energy applicator;

a manipulator including a plurality of links and a plurality of actuators operatively coupled to the plurality of links for moving the energy applicator in one or more degrees of freedom; and

at least one controller configured to:

establish an initial position of the energy applicator;

evaluate a plurality of possible final positions for the energy applicator to move from the initial position, the plurality of possible final positions evaluated with respect to one or more boundaries within which the energy applicator is allowed to move and beyond which the energy applicator is restricted from moving; and

establish a commanded position to which the energy applicator is able to be moved by the manipulator without crossing the one or more boundaries, based on the evaluation of the plurality of possible final positions for the energy applicator.

2. The system of claim 1 , wherein the at least one controller configured to:

operate the manipulator in a manual mode of operation in which a user grasps the surgical instrument and applies a force to the surgical instrument to indicate a desired movement of the energy applicator; and

establish the commanded position to which the energy applicator is able to be moved by the manipulator in the manual mode of operation.

3. The system of claim 1 , wherein the at least one controller is configured to evaluate the plurality of possible final positions in sequence with the commanded position being a last of the plurality of possible final positions evaluated by the at least one controller in a single time frame.

4. The system of claim 1 , wherein the at least one controller is configured to:

calculate a first of the plurality of possible final positions;

determine whether movement of the energy applicator from the initial position to the first of the plurality of possible final positions would cross the one or more boundaries;

calculate a second of the plurality of possible final positions in response to the at least one controller determining that the energy applicator would cross the one or more boundaries if moved from the initial position to the first of the plurality of possible final positions;

establish a new initial position for use in evaluating the second of the plurality of possible final positions;

determine whether movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross the one or more boundaries; and

calculate a third of the plurality of possible final positions in response to the at least one controller determining that the energy applicator would cross the one or more boundaries if moved from the new initial position to the second of the plurality of possible final positions.

5. The system of claim 1 , wherein the at least one controller is configured to generate the plurality of possible final positions in a virtual model coordinate system relative to a manipulator coordinate system.

6. The system of claim 1 , wherein the at least one controller is configured to:

determine a time period when the energy applicator would cross the one or more boundaries upon movement of the energy applicator from the initial position to a first of the plurality of possible final positions based on an initial velocity; and

determine an intersecting point where the energy applicator would cross the one or more boundaries upon movement of the energy applicator from the initial position to the first of the plurality of possible final positions based on the initial velocity.

7. The system of claim 6 , wherein the at least one controller is configured to:

model the surgical instrument as a virtual rigid body; and

determine a first boundary-constraining force to be applied to the virtual rigid body based on the determined time period and intersecting point to prevent progression of the energy applicator beyond the one or more boundaries.

8. The system of claim 7 , wherein the at least one controller is configured to determine a second of the plurality of possible final positions that results from applying the first boundary-constraining force to the virtual rigid body.

9. The system of claim 8 , wherein the at least one controller is configured to establish the second of the plurality of possible final positions as the commanded position.

10. The system of claim 8 , wherein the at least one controller is configured to:

establish a new initial position for use in evaluating the second of the plurality of possible final positions;

determine whether movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross the one or more boundaries;

calculate a second boundary-constraining force to be applied to the virtual rigid body in response to the at least one controller determining that movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross the one or more boundaries;

determine a third of the plurality of possible final positions that results from applying the second boundary-constraining force to the virtual rigid body; and

establish the third of the plurality of possible final positions as the commanded position.

11. The system of claim 10 , wherein the at least one controller is configured to:

establish a maximum number of calculations of boundary-constraining forces to be made in a single time frame;

determine whether the maximum number of calculations have been made in the single time frame; and

establish the commanded position as a last initial position determined in the single time frame to be within the one or more boundaries after the at least one controller makes the maximum number of calculations.

12. The system of claim 1 , wherein the at least one controller is configured to:

identify a broad set of boundary-defining tiles the energy applicator could cross if the energy applicator was moved from the initial position to a first of the plurality of possible final positions; and

identify a narrow set of boundary-defining tiles that are within the broad set of boundary-defining tiles that the energy applicator could cross if the energy applicator was moved from the initial position to the first of the plurality of possible final positions.

13. The system of claim 12 , wherein the at least one controller is configured to:

determine a first of the narrow set of boundary-defining tiles that the energy applicator would cross if the energy applicator was moved from the initial position to the first of the plurality of possible final positions;

determine a time period when the energy applicator would cross the first of the narrow set of boundary-defining tiles upon movement of the energy applicator from the initial position to the first of the plurality of possible final positions based on an initial velocity;

determine an intersecting point where the energy applicator would cross the first of the narrow set of boundary-defining tiles upon movement of the energy applicator from the initial position to the first of the plurality of possible final positions based on the initial velocity;

model the surgical instrument as a virtual rigid body; and

determine a first boundary-constraining force to be applied to the virtual rigid body based on the determined time period and intersecting point to prevent progression of the energy applicator beyond the first of the narrow set of boundary-defining tiles.

14. The system of claim 13 , wherein the at least one controller is configured to determine a second of the plurality of possible final positions that results from applying the first boundary-constraining force to the virtual rigid body.

15. The system of claim 14 , wherein the at least one controller is configured to establish the second of the plurality of possible final positions as the commanded position.

16. The system of claim 14 , wherein the at least one controller is configured to:

establish a new initial position for use in evaluating the second of the plurality of possible final positions;

determine whether movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross any boundary-defining tiles of a second narrow set of boundary-defining tiles;

calculate a second boundary-constraining force to be applied to the virtual rigid body in response to the at least one controller determining that movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross a first boundary-defining tile of the second narrow set of boundary-defining tiles;

determine a third of the plurality of possible final positions that results from applying the second boundary-constraining force to the virtual rigid body; and

establish the third of the plurality of possible final positions as the commanded position.

17. The system of claim 1 , wherein the at least one controller is configured to evaluate the plurality of possible final positions for the energy applicator in a single time frame before moving the energy applicator toward the commanded position and after moving the energy applicator toward an immediately prior commanded position wherein the immediately prior commanded position is established as the initial position.

18. A method of operating a system, the system comprising a surgical instrument including an energy applicator, a manipulator including a plurality of links and a plurality of actuators operatively coupled to the plurality of links for moving the energy applicator in one or more degrees of freedom, and at least one controller, the method comprising the at least one controller performing the steps of:

establishing an initial position of the energy applicator;

evaluating a plurality of possible final positions for the energy applicator to move from the initial position, the plurality of possible final positions evaluated with respect to one or more boundaries within which the energy applicator is allowed to move and beyond which the energy applicator is restricted from moving; and

establishing a commanded position to which the energy applicator is able to be moved by the manipulator without crossing the one or more boundaries, based on the evaluation of the plurality of possible final positions for the energy applicator.

19. The method of claim 18 , further comprising the at least one controller performing the steps of:

operating the manipulator in a manual mode of operation in which a user grasps the surgical instrument and applies a force to the surgical instrument to indicate a desired movement of the energy applicator; and

establishing the commanded position to which the energy applicator is able to be moved by the manipulator in the manual mode of operation.

20. The method of claim 18 , further comprising the at least one controller performing the step of evaluating the plurality of possible final positions in sequence with the commanded position being a last of the plurality of possible final positions evaluated by the at least one controller in a single time frame.

21. The method of claim 18 , further comprising the at least one controller performing the steps of:

calculating a first of the plurality of possible final positions;

determining whether movement of the energy applicator from the initial position to the first of the plurality of possible final positions would cross the one or more boundaries;

calculating a second of the plurality of possible final positions in response to the at least one controller determining that the energy applicator would cross the one or more boundaries if moved from the initial position to the first of the plurality of possible final positions;

establishing a new initial position for use in evaluating the second of the plurality of possible final positions;

determining whether movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross the one or more boundaries; and

calculating a third of the plurality of possible final positions in response to the at least one controller determining that the energy applicator would cross the one or more boundaries if moved from the new initial position to the second of the plurality of possible final positions.

22. The method of claim 18 , further comprising the at least one controller generating the plurality of possible final positions in a virtual model coordinate system relative to a manipulator coordinate system.

23. The method of claim 18 , further comprising the at least one controller performing the steps of:

determining a time period when the energy applicator would cross the one or more boundaries upon movement of the energy applicator from the initial position to a first of the plurality of possible final positions based on an initial velocity; and

determining an intersecting point where the energy applicator would cross the one or more boundaries upon movement of the energy applicator from the initial position to the first of the plurality of possible final positions based on the initial velocity.

24. The method of claim 23 , further comprising the at least one controller performing the steps of:

modeling the surgical instrument as a virtual rigid body; and

determining a first boundary-constraining force to be applied to the virtual rigid body based on the determined time period and intersecting point for preventing progression of the energy applicator beyond the one or more boundaries.

25. The method of claim 24 , further comprising the at least one controller performing the step of determining a second of the plurality of possible final positions that results from applying the first boundary-constraining force to the virtual rigid body.

26. The method of claim 25 , further comprising the at least one controller performing the step of establishing the second of the plurality of possible final positions as the commanded position.

27. The method of claim 25 , further comprising the at least one controller performing the steps of:

establishing a new initial position for use in evaluating the second of the plurality of possible final positions;

determining whether movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross the one or more boundaries;

calculating a second boundary-constraining force to be applied to the virtual rigid body in response to the at least one controller determining that movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross the one or more boundaries;

determining a third of the plurality of possible final positions that results from applying the second boundary-constraining force to the virtual rigid body; and

establishing the third of the plurality of possible final positions as the commanded position.

28. The method of claim 27 , further comprising the at least one controller performing the steps of:

establishing a maximum number of calculations of boundary-constraining forces to be made in a single time frame;

determining whether the maximum number of calculations have been made in the single time frame; and

establishing the commanded position as a last initial position determined in the single time frame to be within the one or more boundaries after the at least one controller makes the maximum number of calculations.

29. The method of claim 18 , further comprising the at least one controller performing the steps of:

identifying a broad set of boundary-defining tiles the energy applicator could cross if the energy applicator was moved from the initial position to a first of the plurality of possible final positions; and

identifying a narrow set of boundary-defining tiles that are within the broad set of boundary-defining tiles that the energy applicator could cross if the energy applicator was moved from the initial position to the first of the plurality of possible final positions.

30. The method of claim 29 , further comprising the at least one controller performing the steps of:

determining a first of the narrow set of boundary-defining tiles that the energy applicator would cross if the energy applicator was moved from the initial position to the first of the plurality of possible final positions;

determining a time period when the energy applicator would cross the first of the narrow set of boundary-defining tiles upon movement of the energy applicator from the initial position to the first of the plurality of possible final positions based on an initial velocity;

determining an intersecting point where the energy applicator would cross the first of the narrow set of boundary-defining tiles upon movement of the energy applicator from the initial position to the first of the plurality of possible final positions based on the initial velocity;

modeling the surgical instrument as a virtual rigid body; and

determining a first boundary-constraining force to be applied to the virtual rigid body based on the determined time period and intersecting point to prevent progression of the energy applicator beyond the first of the narrow set of boundary-defining tiles.

31. The method of claim 30 , further comprising the at least one controller performing the step of determining a second of the plurality of possible final positions that results from applying the first boundary-constraining force to the virtual rigid body.

32. The method of claim 31 , further comprising the at least one controller performing the step of establishing the second of the plurality of possible final positions as the commanded position.

33. The method of claim 31 , further comprising the at least one controller performing the steps of:

establishing a new initial position for use in evaluating the second of the plurality of possible final positions;

determining whether movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross any boundary-defining tiles of a second narrow set of boundary-defining tiles;

calculating a second boundary-constraining force to be applied to the virtual rigid body in response to the at least one controller determining that movement of the energy applicator from the new initial position to the second of the plurality of possible final positions would cross a first boundary-defining tile of the second narrow set of boundary-defining tiles;

determining a third of the plurality of possible final positions that results from applying the second boundary-constraining force to the virtual rigid body; and

establishing the third of the plurality of possible final positions as the commanded position.

34. The method of claim 18 , further comprising the at least one controller performing the step of evaluating the plurality of possible final positions for the energy applicator in a single time frame before moving the energy applicator toward the commanded position and after moving the energy applicator toward an immediately prior commanded position wherein the immediately prior commanded position is established as the initial position.

35. At least one controller configured to operate a system comprising a surgical instrument including an energy applicator, and a manipulator including a plurality of links and a plurality of actuators operatively coupled to the plurality of links for moving the energy applicator in one or more degrees of freedom, the at least one controller configured to:

establish an initial position of the energy applicator;

evaluate a plurality of possible final positions for the energy applicator to move from the initial position, the plurality of possible final positions evaluated with respect to one or more boundaries within which the energy applicator is allowed to move and beyond which the energy applicator is restricted from moving; and

establish a commanded position to which the energy applicator is able to be moved by the manipulator without crossing the one or more boundaries, based on the evaluation of the plurality of possible final positions for the energy applicator.