Systems and methods for avoiding collisions between manipulator arms using a null-space

Patent metadata

Field	Value
Publication number	US-9345544-B2
Application number	US-201313906819-A
Country	US
Kind code	B2
Filing date	May 31, 2013
Priority date	Sep 17, 1999
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

Devices, systems, and methods for avoiding collisions between manipulator arms using a null-space are provided. In one aspect, the system calculates an avoidance movement using a relationship between reference geometries of the multiple manipulators to maintain separation between reference geometries. In certain embodiments, the system determines a relative state between adjacent reference geometries, determines an avoidance vector between reference geometries, and calculates an avoidance movement of one or more manipulators within a null-space of the Jacobian based on the relative state and avoidance vector. The joints may be driven according to the calculated avoidance movement while maintaining a desired state of the end effector or a remote center location about which an instrument shaft pivots and may be concurrently driven according to an end effector displacing movement within a null-perpendicular-space of the Jacobian so as to effect a desired movement of the end effector or remote center.

First claim

What is claimed is:

1. A robotic method for a robotic system that includes a first manipulator arm and a second manipulator arm, each manipulator arm including a movable distal portion, a proximal portion coupled to an associated base, and a plurality of joints between the distal portion and the base, the plurality of joints having a joint space with sufficient degrees of freedom to allow a range of differing joint states of the plurality of joints for a given state of the distal portion of each manipulator arm, and the method comprising:
determining a first reference geometry of the first manipulator arm and a second reference geometry of the second manipulator arm, the first and second reference geometries being movable with the associated manipulator arms within a workspace and having ranges of motion that overlap within the workspace;
determining a relative state between the first reference geometry and the second reference geometry in the workspace and a desired avoidance vector;
calculating an avoidance movement of one or more joints of the pluralities of joints of the first and second manipulator arms so as to maintain a separation between the first and second reference geometries in the workspace, the avoidance movement being based on the desired avoidance vector so that the avoidance movement is contained within a null-space of a Jacobian associated with the respective manipulator arm; and
driving the one or more joints of the pluralities of joints of the first and second manipulator arms according to the calculated avoidance movement.

2. The robotic method of claim 1 , wherein the avoidance movement is calculated in response to the determined relative state when the relative state corresponds to a less than desired clearance between the first and second reference geometries, and the calculated avoidance movement along the desired avoidance vector corresponds to an increase in clearance.

3. The robotic method of claim 1 , wherein the relative state is determined using three-dimensional coordinates corresponding to the workspace of the manipulator arms.

4. The robotic method of claim 2 , wherein the avoidance movement calculation includes converting the desired avoidance vector between the workspace and the joint space of the manipulator arms.

5. The robotic method of claim 1 , wherein calculating the avoidance movement comprises:
determining nearest points between the first and second reference geometries;
calculating an avoidance vector between the nearest points in the workspace of the manipulator arms, the calculated avoidance vector corresponding to the desired avoidance vector;
transforming the calculated avoidance vector into a joint velocity space; and
projecting the calculated avoidance vector transformed into the joint velocity space onto the null-space to obtain the avoidance movement.

6. The robotic method of claim 1 , wherein calculating the avoidance movement comprises:
calculating nearest points between the first and second reference geometries to determine one or more avoidance points on the manipulator arm;
determining an avoidance vector between the nearest points in a workspace of the manipulator arms, the avoidance vector in the workspace corresponding to the desired avoidance vector;
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 vector in the workspace into a coefficient for the original null-space basis vectors to obtain the avoidance movement.

7. The robotic method of claim 2 , wherein the relative state is determined using joint sensor data from each of the first and second manipulator arms.

8. The robotic method of claim 2 , wherein the first reference geometry includes a line segment corresponding to a structure of the first manipulator arm and the second reference geometry includes a line segment corresponding to a structure of the second manipulator arm.

9. The robotic method of claim 8 , wherein each of the first and second reference geometries comprise a plurality of line segments each corresponding to a structure on the respective manipulator arm, and determining the relative state further comprises:
determining a line segment of the plurality of line segments of the first reference geometry nearest a line segment of the plurality of line segments of the second reference geometry, the nearest line segments corresponding to nearest structures of the first and second manipulator; and
calculating the desired avoidance vector so as to extend through the nearest line segments.

10. The robotic method of claim 9 , wherein determining the nearest line segment comprises calculating the nearest distance between the line segments of the first reference geometry and the second reference geometry.

11. The robotic method of claim 1 , wherein calculating the avoidance movement comprises:
calculating a repulsion force between the first and second reference geometries sufficient to maintain the separation between the first and second reference geometries when applied in a direction of the desired avoidance vector, and
calculating a movement of the one or more joints of the pluralities of joints of the first and second manipulator arms in response to the repulsion force applied on the first and second manipulator arms along the desired avoidance vector.

12. The robotic method of claim 1 , wherein calculating the avoidance movement comprises:
calculating a repulsion commanded velocity between the first and second reference geometries sufficient to maintain the separation between the first and second reference geometries when applied in a direction of the desired avoidance vector, and
calculating a movement of the one or more joints of the pluralities of joints of the first and second manipulator arms in response to the repulsion commanded velocity applied at line segments that correspond to structures of the first and second manipulator arms along the desired avoidance vector.

13. The robotic method of claim 11 , wherein the repulsion force has a magnitude inversely related to a separation distance between the first and second reference geometries.

14. The robotic method of claim 12 , wherein the repulsion commanded velocity has a magnitude inversely related to a separation distance between the first and second reference geometries.

15. The robotic method of claim 1 , wherein the first and second manipulator arms have ranges of motion that overlap, and the relative state between the first and second manipulator arms is determined by using proximity sensors mounted on driven linkages of the first and second manipulator arms.

16. The robotic method of claim 1 , wherein the relative state between manipulator arms is determined using sensed positional information received from at least one mechanical, optical, ultrasonic, capacitive, inductive, resistive, or joint sensor.

17. The robotic method of claim 1 , wherein the avoidance movement is independent of a planar relationship between the first and second manipulator arms when each arm is disposed in a substantially planar configuration, the avoidance movement allowing for an increased range of configurations for each arm while inhibiting collisions between the first and second manipulator arms where their respective ranges of motion overlap.

18. The robotic method of claim 1 , wherein determining the relative state between the first and second reference geometries comprises any or all of a relative position, r

Assignees

• Intuitive Surgical Operations

Inventors

• Hourtash Arjang M
• Hingwe Pushkar
• Schena Bruce Michael
• Devengenzo Roman L

Classifications

• B25J17/00

  Joints · CPC title

• B25J9/1676

  Avoiding collision or forbidden zones · CPC title

• B25J13/06

  Control stands, e.g. consoles, switchboards · CPC title

• B25J9/1607 Primary

  Calculation of inertia, jacobian matrixes and inverses · CPC title

• G05B2219/39135

  For multiple manipulators operating at same time, avoid collision · CPC title