Ratcheting for master alignment of a teleoperated minimally-invasive surgical instrument

1. A teleoperated system comprising:

a master grip; and

a ratcheting system coupled to the master grip and configured to be coupled to a slave instrument, the ratcheting system being configured to align the master grip with the slave instrument by:

determining a commanded angular velocity for the slave instrument based on a command from the master grip;

determining a current alignment error between an alignment of the master grip and an alignment of the slave instrument; and

altering the commanded angular velocity for the slave instrument based on the current alignment error.

2. The teleoperated system of claim 1 , wherein the ratcheting system is further configured to introduce a control system error to alter the commanded angular velocity.

3. The teleoperated system of claim 1 , wherein the ratcheting system is further configured to use a new alignment error to alter the commanded angular velocity only if the new alignment error is smaller than the current alignment error.

4. The teleoperated system of claim 1 , wherein the current alignment error is a rotation angle error between the alignment of the master grip and the alignment of the slave instrument.

5. The teleoperated system of claim 1 , wherein to alter the commanded angular velocity, the ratcheting system is configured to penalize a commanded movement of the slave instrument based on the current alignment error and a penalty profile.

6. The teleoperated system of claim 5 , wherein the penalty profile comprises a continuous and monotonic penalty profile.

7. The teleoperated system of claim 5 , wherein the penalty profile comprises a first region for values of the current alignment error less than a first value, a third region for values of the current alignment error greater than a second value, and a second region for values of the current alignment error between the first value and the second value.

8. The teleoperated system of claim 1 , wherein to alter the commanded angular velocity, the ratcheting system is configured to:

select a scale factor based on the current alignment error; and

adjust the commanded angular velocity based on the scale factor.

9. The teleoperated system of claim 1 , wherein the master grip is selected from a group consisting of: a master grip without powered alignment and a master grip with powered alignment.

10. The teleoperated system of claim 1 , wherein:

the slave instrument includes a tip;

the commanded angular velocity is a commanded angular velocity of the tip;

the current alignment error is a current alignment error between the master grip and the tip; and

the altered commanded angular velocity is an altered commanded angular velocity for the tip.

11. The teleoperated system of claim 1 , wherein the ratcheting system alters the commanded angular velocity to speed up convergence of alignment between the slave instrument and the master grip relative to convergence of alignment between the slave instrument and the master grip without introduction of the altered commanded angular velocity.

12. A method of controlling a teleoperated system, the method comprising:

determining, by one or more processors of the teleoperated system, a commanded angular velocity for a slave instrument of the teleoperated system based on a command from a master grip of the teleoperated system;

determining, by the one or more processors, a current alignment error between an alignment of the master grip and an alignment of the slave instrument; and

altering, by the one or more processors, the commanded angular velocity for the slave instrument based on the current alignment error.

13. The method of claim 12 , further comprising introducing a control system error to alter the commanded angular velocity.

14. The method of claim 12 , wherein the current alignment error is a rotation angle error between the alignment of the master grip and the alignment of the slave instrument.

15. The method of claim 12 , wherein altering the commanded angular velocity comprises penalizing a commanded movement of the slave instrument based on the current alignment error and a penalty profile.

16. The method of claim 15 , wherein the penalty profile comprises a first region for values of the current alignment error less than a first value, a third region for values of the current alignment error greater than a second value, and a second region for values of the current alignment error between the first value and the second value.

17. A non-transitory computer-readable medium comprising computer-readable code which when executed by one or more processors associated with a teleoperated system are adapted to cause the one or more processors to perform a method comprising:

determining a commanded angular velocity for a slave instrument of the teleoperated system based on a command from a master grip of the teleoperated system;

determining a current alignment error between an alignment of the master grip and an alignment of the slave instrument; and

altering the commanded angular velocity for the slave instrument based on the current alignment error.

18. The non-transitory computer-readable medium of claim 17 , wherein the method further comprises introducing a control system error to alter the commanded angular velocity.

19. The non-transitory computer-readable medium of claim 17 , wherein the current alignment error is a rotation angle error between the alignment of the master grip and the alignment of the slave instrument.

20. The non-transitory computer-readable medium of claim 17 , wherein altering the commanded angular velocity comprises penalizing a commanded movement of the slave instrument based on the current alignment error and a penalty profile.