Alignment difference safety in a master-slave robotic system

Patent metadata

Field	Value
Publication number	US-10159536-B2
Application number	US-201615542398-A
Country	US
Kind code	B2
Filing date	Jan 8, 2016
Priority date	Jan 9, 2015
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

A method, a non-transitory computer readable medium, and an apparatus for operating the robotic control system comprising a master apparatus ( 64 ) in communication with an input device ( 58, 60 ) having a handle ( 102 ) and a slave system ( 54, 74 ) having a tool ( 66, 67 ) having an end effector ( 73 ) whose position and orientation is determined in response to a current position and current orientation of the handle. The method involves producing a desired end effector position and orientation in response to a current position and orientation of the handle. The method involves causing the input device to provide haptic feedback that impedes translational movement of the handle, while permitting rotational movement of the handle and preventing movement of the end effector, when a rotational alignment difference between the handle and the end effector meets a disablement criterion. The method further involves re-enabling translational movement of the handle when the rotational alignment difference meets an enablement criterion.

First claim

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of operating a robotic control system comprising a master apparatus in communication with an input device having a handle capable of translational and rotational movement and a slave system having a tool positioning device holding a tool having an end effector whose position and orientation is determined in response to a position and orientation of the handle, the method comprising:
producing a desired end effector position and a desired end effector orientation of the end effector, in response to a current position and a current orientation of the handle;
causing the input device to provide haptic feedback that impedes translational movement of the handle, while permitting rotational movement of the handle and while disabling translational and rotational movement of the end effector in response to movement of the handle, when a rotational alignment difference between the handle and the end effector meets a disablement criterion; and
enabling translational movement of the handle when the rotational alignment difference meets an enablement criterion.

2. The method of claim 1 wherein producing said desired end effector position and desired end effector orientation comprises:
causing the master apparatus to receive current handle position signals ( MCURR ) and current handle orientation signals (R MCURR ) representing a current position and a current orientation respectively of the handle of the input device; and
causing the master apparatus to produce new end effector position signals ( EENEW ) and new end effector orientation signals (R EENEW ) defining said desired end effector position and said desired end effector orientation, respectively of the end effector, in response to said current handle position signals ( MCURR ) and said current handle orientation signals (R MCURR ).

3. The method of claim 2 wherein said causing the master apparatus to receive said current handle position signals and said current handle orientation signals comprises causing the master apparatus to periodically receive said current handle position signals and said current handle orientation signals.

4. The method of claim 2 further comprising causing the master apparatus to determine said rotational alignment difference between the handle and the end effector in response to said current handle orientation signals (R MCURR ) and said new end effector orientation signals (R EENEW ).

5. The method of claim 4 wherein causing the master apparatus to determine a rotational alignment difference between the handle and the end effector comprises causing the master apparatus to determine an angle through which the end effector would have to be rotated to align it with the current handle orientation.

6. The method of claim 5 further comprising causing the master apparatus to determine whether said angle of rotation is less than a threshold.

7. The method of claim 3 wherein causing the input device to provide haptic feedback comprises causing the master apparatus to transmit a haptic feedback signal to the input device to cause the input device to provide said haptic feedback that impedes said translational movement of the handle.

8. The method of claim 3 wherein
enabling translational movement of the handle when the rotational alignment difference meets an enablement criterion comprises:
transmitting to the slave system a control signal identifying said end effector position and orientation signals based on a current position and orientation of the handle; and

wherein disabling movement of the end effector in response to any movement of the handle comprises transmitting to the slave system said control signal identifying said end effector position and orientation signals determined from a previous position and orientation of the handle.

9. The method of claim 2 further comprising causing the master apparatus to receive an enablement signal.

10. The method of claim 9 further comprising determining a state of the enablement signal such that the enablement signal selectively has an active state or an inactive state.

11. The method of claim 10 further comprising:
causing the master apparatus to detect a change of said enablement signal from the inactive state to the active state and when said change is detected:
causing the master apparatus to store said current handle position signals ( MCURR ) and said current handle orientation signals (R MCURR ) as master base position signals ( MBASE ) and master base orientation signals (R MBASE ) respectively, in response to said change of said enablement signal; and
causing the master apparatus to store said new end effector position signals ( EENEW ) and said new end effector orientation signals (R EENEW ) as end effector base position signals ( EEBASE ) and end effector base orientation signals (R EEBASE ) respectively, in response to said change of said enablement signal.

12. The method of claim 11 wherein said causing the master apparatus to compute said new end effector position signals ( EENEW ) and said new end effector orientation signals (R EENEW ) comprises causing the master apparatus to compute said new end effector position signals and said new end effector orientation signals according to the following relations:
EENEW =A ( MCURR − MBASE )+ EEBASE ; and

R EENEW =R EEBASE R MBASE −1 R MCURR ;
wherein A is a scalar value representing a scaling factor in translational motion between the master apparatus and the slave system.

13. The method of claim 10 further comprising causing a control signal to be dependent on the state of said enablement signal, such that
said control signal identifies said new end effector position and orientation signals based on a current position and orientation of the handle when said alignment difference is less than the disablement criterion and said enablement signal is in the active state; and
said control signal identifies said new end effector position and orientation signals based on a previous position and orientation of the handle when said enablement signal is in the inactive state.

14. The method of claim 1 further comprising causing the master apparatus to produce annunciation signals for causing an annunciator to annunciate an indication of a relative rotational alignment of said handle and said end effector.

15. The method of claim 14 wherein said causing the master apparatus to produce annunciation signals includes causing the master apparatus to produce display control signals for causing a display to depict said relative alignment.

16. A non-transitory computer readable medium encoded with codes comprising instructions that, when executed by a processor, to cause the processor to execute the method of claim 1 .

17. An apparatus for use in a robotic control system, the apparatus in communication with an input device having a handle capable of translational and rotational movement and in communication with a slave system having a tool positioning device holding a tool having an end effector whose position and orientation is determined in response to a position and orientation of the handle, the apparatus comprising:
producing means for producing a desired end effector position and a desired end effector orientation of the end effector, in response to a current position and a current orientation of the handle;
causing means for causing the input device to provide haptic feedback that impedes translational movement of the handle, while causin

Assignees

• Titan Med Inc

Inventors

• Kralicky Joseph
• Cameron Peter
• Robert Rene

Classifications

• A61B34/77

  Manipulators with motion or force scaling · CPC title

• A61B34/71

  Manipulators operated by drive cable mechanisms · CPC title

• A61B34/30 Primary

  Surgical robots · CPC title

• G05B2219/35419

  Four and more-DOF hand controller, joystick, manipulandum · CPC title

• G05B2219/45117

  Medical, radio surgery manipulator · CPC title