Manipulator arm-to-patient collision avoidance using a null-space

• US 9,492,235 B2
• Filed: 05/31/2013
• Issued: 11/15/2016
• Est. Priority Date: 09/17/1999
• Status: Active Grant

• Current Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Original Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Inventors: Hourtash, Arjang M., Hingwe, Pushkar, Schena, Bruce Michael, Devengenzo, Roman L.
• Primary Examiner(s): Amin, Bhavesh V
• Application Number:
  US13/906,713
• Publication Number:
  US 20130325029A1
• Time in Patent Office: 1,264 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2034/305 Details of wrist mechanisms at distal ends of robotic arms
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: A61B 34/37 Master-slave robots A61B34/35 takes precedence
• CPC Class Codes: B25J 9/1607 Calculation of inertia, jacobian matrixes and inverses
• CPC Class Codes: B25J 9/1676 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 2219/39135 For multiple manipulators operating at same time, avoid collision
• CPC Class Codes: G05B 2219/40202 Human robot coexistence
• CPC Class Codes: G05B 2219/40371 Control trajectory to avoid joint limit as well as obstacle collision
• CPC Class Codes: G05B 2219/40471 Using gradient method
• CPC Class Codes: G05B 2219/40492 Model manipulator by spheres for collision avoidance
• CPC Class Codes: G05B 2219/45117 Medical, radio surgery manipulator

Abstract

Devices, systems, and methods for avoiding collisions between a manipulator arm and an outer patient surface by moving the manipulator within a null-space. In response to a determination that distance between an avoidance geometry and obstacle surface, corresponding to a manipulator-to-patient distance is less than desired, the system calculates movement of one or more joints or links of the manipulator within a null-space of the Jacobian to increase this distance. The joints are driven according to the reconfiguration command and calculated movement so as to maintain a desired state of the end effector. In one aspect, the joints are also driven according to a calculated end effector displacing movement within a null-perpendicular-space of the Jacobian to effect a desired movement of the end effector or remote center while concurrently avoiding arm-to-patient collisions by moving the joints within the null-space.

Claims

1. In a robotic system comprising a base and a manipulator arm, the manipulator arm comprising a proximal portion coupled to the base, a movable distal portion, and a plurality of joints between the base and the distal portion, and the plurality of joints together having sufficient degrees of freedom to allow a range of different joint states of the plurality of joints for a given state of the distal portion, a method comprising:

calculating a distal portion displacing movement of the plurality of joints to effect a desired distal portion movement for a desired state of the distal portion within a surgical work site in response to a manipulation command received from a user input, the calculating of the distal portion displacing movement including calculating joint movement within a null-perpendicular-space of a Jacobian, and the null-perpendicular-space being orthogonal to a null-space of the Jacobian;

calculating an avoidance movement of the plurality of joints within the null-space of the Jacobian to provide a desired clearance between the manipulator arm and a patient tissue surface; and

driving the plurality of joints according to the distal portion displacing movement and the avoidance movement to provide the desired clearance between the manipulator arm and a patient tissue surface and to maintain the desired state of the distal portion.

2. The method of claim 1, wherein the joints of the plurality of joints are driven according to the avoidance movement in response to a determination of insufficient clearance between the manipulator arm and the patient tissue surface.

3. The method of claim 1, wherein the joints of the plurality of joints are driven according to the avoidance movement concurrently with driving the plurality of joints according to the distal portion displacing movement.

4. The method of claim 1, wherein the distal portion comprises or is configured to releasably support a surgical instrument having an elongate shaft extending distally to a surgical end effector, wherein the distal portion displacing movement is calculated to effect a desired end effector state, and wherein the avoidance movement of the plurality of joints is calculated to maintain the desired end effector state during the driving of the plurality of joints.

5. The method of claim 1, wherein the manipulator arm is configured to support a tool having a shaft with an intermediate portion extending along an insertion axis of the tool to a distal end effector, wherein at least some joints of the plurality of joints mechanically constrain movement of the distal portion relative to the base so that the distal portion of the manipulator arm pivots about a remote pivotal center to facilitate movement of the end effector within the surgical work site, wherein the work site is accessed by inserting the shaft through an insertion opening, and wherein the tissue surface comprises a skin surface outside the opening.

6. The method of claim 1, further comprising

determining an avoidance geometry corresponding to a movable position of the proximal portion of the manipulator arm and determining an obstacle surface corresponding to a position of the patient tissue surface, wherein the avoidance movement is calculated to maintain a desired relationship between the avoidance geometry and the obstacle surface.

7. The method of claim 6, wherein the joints of the plurality of joints are driven according to the avoidance movement in response to a determination that the avoidance geometry is less than a desired minimum distance from the obstacle surface.

8. The method of claim 6, wherein the obstacle surface is determined by using one or more sensors of the plurality of joints of the manipulator.

9. The method of claim 6, wherein the obstacle surface is determined by using a measured position of a remote center of one or more manipulator arms, the remote center being a point about which the distal portion of the respective manipulator arm pivots adjacent a minimally invasive aperture.

10. The method of claim 9, wherein the obstacle surface is determined by approximating the obstacle surface to intersect with the one or more remote center positions.

11. The method of claim 10, wherein the obstacle surface is determined by modeling the obstacle surface by fitting a plurality of measured remote center positions to a predetermined shape.

12. The method of claim 6, wherein the obstacle surface is determined by using sensed positional information received from any of a mechanical, optical, ultrasonic, capacitive, inductive, resistive, or joint sensor.

13. The method of claim 6, wherein the obstacle surface is determined by using sensed positional information received from proximity sensors mounted on driven linkages of the manipulator arm having a ranges of motion that overlaps with the obstacle surface.

14. The method of claim 6, wherein calculating the avoidance movement comprises determining a distance between the avoidance geometry and the obstacle surface.

15. The method of claim 6, wherein calculating the avoidance movement comprises:

determining nearest points between the avoidance geometry and the obstacle surface;

calculating an avoidance vector between the nearest points in a work space of the manipulator arm;

transforming the avoidance vector into the joint velocity space; and

projecting the avoidance vectors transformed into the joint velocity space onto the null-space to obtain the avoidance movement.

16. The method of claim 6, wherein calculating the avoidance movement comprises:

calculating nearest points between the avoidance geometry and the obstacle surface to determine one or more avoidance points on the manipulator arm;

determining an avoidance vector between the nearest points in a work space of the manipulator arm;

transforming original null-space basis vectors of the manipulator arm into motion of the one or more avoidance points on the manipulator arm; and

combining the transformed null-space basis vectors with the avoidance vectors in the work space into a coefficient for the original null-space basis vectors to obtain the avoidance movement.

17. The method of claim 14, wherein the distance between the avoidance geometry and the obstacle surface is determined by calculating a first distance between a first avoidance geometry and a second obstacle surface.

18. The method of claim 16, wherein the avoidance geometry is a point on the manipulator.

19. The method of claim 16, wherein the avoidance geometry comprises a plane, sphere, or other geometric shape.

20. The method of claim 16, wherein the obstacle surface comprises a plane, sphere, or other geometric shape.

21. The method of claim 14, wherein the distance between the avoidance geometry and the obstacle surface is determined by calculating a first distance between a first horizontal plane extending through the avoidance geometry and a second horizontal plane extending through the obstacle.

22. The method of claim 6, wherein the avoidance geometry corresponds to one or more features of the manipulator arm proximal of the end effector so that the avoidance movement prevents the one or more features from contacting the patient tissue surface.

23. The method of claim 6, the method further comprising:

calculating a potential field within a joint-space of the plurality of joints, wherein lower potentials correspond to greater distances between the avoidance geometry and the obstacle surface and higher potentials correspond to smaller distances between the avoidance geometry and the obstacle surface, and

wherein the avoidance movement is calculated to maintain or decrease the value of the potential field.

24. The method of claim 14, wherein a vector extends along the distal portion from the surgical work site to the avoidance geometry, and the distance between the avoidance geometry and the obstacle surface is determined by measuring a component of the vector substantially orthogonal to the obstacle surface nearest the avoidance geometry.

25. The method of claim 6, wherein the distal portion displacing movement of the plurality of joints is calculated so that a first joint of the plurality of joints is not driven to effect the distal portion displacing movement.

26. The method of claim 6, wherein the distal portion displacing movement of the plurality of joints is calculated so that a first joint of the plurality of joints is not driven.

27. The method of claim 25, wherein the avoidance movement of the plurality of joints is calculated to drive at least the first joint to effect the avoidance movement of the manipulator arm.

28. The method of claim 25, wherein the driving of the first joint during the avoidance movement comprises providing a substantially constant joint articulation velocity of the first joint, and wherein the avoidance movement is calculated to provide the substantially constant velocity during the duration of the avoidance command.

29. The method of claim 1, wherein the desired state of the distal portion comprises at least one of a distal portion position, orientation, or velocity relative to the base.

30. The method of claim 6, wherein at least some of the plurality of joints comprise remote spherical center joints disposed distally of the proximal portion and proximally of the distal portion, wherein the remote spherical center joints are mechanically constrained so that articulation of the remote spherical center joints pivot the distal portion of the manipulator arm about first, second, and third remote center axes, the first, second, and third remote center axes intersecting at the remote center.

31. The method of claim 6, wherein a first joint couples the proximal portion to the base, and an intermediate link is disposed proximal of and adjacent to the distal portion with a second joint therebetween, the second joint comprising a revolute joint mechanically constraining movement of the distal portion relative to the intermediate link to rotation about a second joint axis, and the second joint axis extending from the second joint distally toward the intermediate portion axis to intersect the insertion axis at the remote center.

32. The method of claim 6, wherein the manipulator arm includes a distal end effector supported by the distal portion and a series of kinematically joined links extending between the proximal portion and the distal end effector, wherein the proximal portion is coupled to the base by a first joint such that the proximal portion of the manipulator arm moves relative to the base during the avoidance movement of the links, wherein the first joint comprises a revolute joint that supports the links of the manipulator arm such that joint movement of the revolute joint pivots the links of the manipulator arm about a pivotal axis of the revolute joint, and wherein the pivotal axis extends from the revolute joint and through the remote center.

33. The method of claim 30, further comprising constraining movement of the remote spherical center joints with a parallelogram linkage system including:

a parallelogram linkage base coupled to the base for rotation about a first remote center axis intersecting the remote center;

a first link having a first link proximal end and a first link distal end, the first link proximal end coupled to the parallelogram linkage base at a base joint, the first link distal end configured to support the tool; and

a second link having a second link proximal end and a second link distal end, the second link proximal end coupled to the first link distal end, the second link distal end configured to support the tool so that an insertion axis of the tool is constrained to rotation about a second remote center axis intersecting the remote center.

34. The method of claim 33, wherein the remote spherical center joints constrain motion of the insertion axis to pivotal motion about first and second remote center axes extending through the remote center, and wherein the first joint is configured to constrain motion of the insertion axis to rotation about a third remote center axis extending through the remote center.

35. The method of claim 1, wherein the joints of the plurality of joints are driven separately according to the avoidance movement and the distal portion displacing movement.