Method and apparatus for collision-free motion planning of a manipulator

Patent metadata

Field	Value
Publication number	US-11279033-B2
Application number	US-201916568309-A
Country	US
Kind code	B2
Filing date	Sep 12, 2019
Priority date	Sep 13, 2018
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

A method for collision-free motion planning of a first manipulator of a robotic control apparatus from a starting point to a destination point. The method includes repeatedly determining a target path of the first manipulator to the destination point with a global planner, continuously determining a movement of the first manipulator with a local planner based on a current target path of the global planner, and performing the movement by the first manipulator in parallel with the determination by the global planner and the local planner.

First claim

What is claimed is:

1. A method for collision-free motion planning of a first manipulator from a starting point to a destination point, the method comprising:
repeatedly determining a target path of the first manipulator to the destination point with a global planner;
continuously determining a movement of the first manipulator with a local planner based on a current target path of the global planner; and
performing the movement by the first manipulator in parallel with the determination by the global planner and the local planner,
wherein, in response to failure of planning by the global planner, moving the first manipulator is continued exclusively based on the local planner.

2. The method of claim 1 , wherein the global planner continuously determines the target path.

3. The method of claim 1 , wherein the global planner comprises a deterministic planner.

4. The method of claim 3 , wherein the deterministic planner is based on a dynamic roadmap (DRM).

5. The method of claim 1 , wherein the global planner inquires a result of the local planner during re-planning and takes the result into account when determining the target path.

6. The method of claim 1 , wherein the local planner is based on model predictive control (MPC) and the determination of the movement is based on optimization by solving a dynamic optimization problem.

7. The method of claim 6 , wherein the dynamic optimization problem comprises a cost function that weights a deviation of the first manipulator from the target path and a deviation of a current path parameter from a target parameter specified by the target path.

8. The method of claim 7 , wherein the dynamic optimization problem further comprises path dynamics and path input constraints.

9. The method of claim 8 , wherein the path dynamics are based on the target path of the global planner.

10. The method of claim 6 , wherein the dynamic optimization problem further comprises at least one inequality constraint for a distance to collisions.

11. The method of claim 1 , wherein at least one of the global planner and the local planner are used to perform at least one of:
partially predicting a movement of an obstacle and
artificially enlarging a representation of an obstacle.

12. The method of claim 1 , further comprising additional motion planning for at least a second manipulator, wherein the additional motion planning is carried out in parallel and coordinated with the collision-free motion planning of the first manipulator.

13. The method of claim 1 , wherein the determining the target path with the global planner is performed continuously, repeating at a rate that is at least one order of magnitude slower than a rate at which the continuously determining with the local planner is repeated.

14. A method for collision-free motion planning of a first manipulator from a starting point to a destination point, the method comprising:
repeatedly determining a target path of the first manipulator to the destination point with a global planner;
continuously determining a movement of the first manipulator with a local planner based on a current target path of the global planner; and
performing the movement by the first manipulator in parallel with the determination by the global planner and the local planner,
wherein execution of the determination by the global planner is adjustable via a defined condition, and
wherein an unconditional execution, no execution, or conditional execution of the determination by the global planner can be set via the defined condition.

15. The method of claim 14 , wherein the conditional execution depends on:
whether at least one of a determined target path and a determined movement is valid in a defined planning horizon and
whether a distance between a current state and a target state has been reduced during a last determination cycle of the local planner.

16. The method of claim 14 , wherein moving the first manipulator is paused in response to failure of planning by the global planner.

17. A robotics control apparatus comprising:
a manipulator; and
a control unit configured to:
implement a global planner and a local planner,
repeatedly determine a target path of the manipulator from a starting point to a destination point with the global planner,
continuously determine a movement of the manipulator with the local planner based on a current target path of the global planner,
actuate the movement by the manipulator in parallel with the determination by the global planner and the local planner; and
in response to failure of planning by the global planner, continue actuating the movement of the manipulator exclusively based on the local planner.

18. The robotics control apparatus of claim 17 , wherein:
execution of the determination by the global planner is adjustable via a defined condition and
an unconditional execution, no execution, or conditional execution of the determination by the global planner can be set via the defined condition.

19. The robotics control apparatus of claim 18 , wherein the conditional execution depends on:
whether at least one of a determined target path and a determined movement is valid in a defined planning horizon and
whether a distance between a current state and a target state has been reduced during a last determination cycle of the local planner.

20. The robotics control apparatus of claim 17 , wherein the control unit is configured to determine the target path with the global planner continuously, repeating at a rate that is at least one order of magnitude slower than a rate at which the movement is determined with the local planner.

Assignees

• Pilz Gmbh & Co Kg

Inventors

• Graichen Knut
• Voelz Andreas
• Bakovic Daniel

Classifications

• B25J9/1666 Primary

  Avoiding collision or forbidden zones · CPC title

• B25J9/1676

  Avoiding collision or forbidden zones · CPC title

• G05B2219/40477

  Plan path independent from obstacles, then correction for obstacles · CPC title

• G05B2219/40475

  In presence of moving obstacles, dynamic environment · CPC title