Robots with collision avoidance functionality

• US 8,311,731 B2
• Filed: 03/20/2008
• Issued: 11/13/2012
• Est. Priority Date: 03/23/2007
• Status: Expired due to Fees

• Current Assignee: Arriver Software AB (Qualcomm, Inc.)
• Original Assignee: Honda Research Institute Europe GmbH (Honda Motor Company)
• Inventors: Sugiura, Hisashi, Janssen, Herbert, Gienger, Michael
• Primary Examiner(s): MANCHO, RONNIE M
• Application Number:
  US12/052,483
• Publication Number:
  US 20080234864A1
• Time in Patent Office: 1,699 Days
• Field of Search: 700/255, 700/250, 700/245, 700/247, 700/251, 700/61, 700/252, 700/246, 318/568.11, 318/568.12, 395/86, 701/301, 345/474, 345/473, 345/475, 703/2
• US Class Current: 701/301
• CPC Class Codes: B25J 9/1666 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 2219/39082 Collision, real time collision avoidance
• CPC Class Codes: G05B 2219/39088 Inhibit movement in one axis if collision danger
• CPC Class Codes: G05B 2219/39096 Self-collision, internal collison, collision between links of one robot
• CPC Class Codes: G05B 2219/40477 Plan path independent from obstacles, then correction for obstacles
• CPC Class Codes: G05B 2219/40492 Model manipulator by spheres for collision avoidance

Abstract

A robot is provided with a motion control unit that avoids collision between segments of the robot or between segments of the robot and other objects. The motion control unit of the robot comprises a distance computing module, a whole body control module, a collision avoidance module, and a blending control unit. The distance computing module calculates two closest points of different segments of the robot connected to each other via at least one joint or a segment of the robot and another object. The collision avoidance module is provided with the information about the two closest points. The blending control unit combines the weighted output control signals of the whole body control module and the collision avoidance control module. The weight of the whole body control output signal is higher when the risk of collision is lower. The weight of the collision avoidance control output signal is higher when the risk of collision is higher. The collision avoidance module is designed to control a collision avoidance action only in the direction parallel to a line connecting between the two closest points.

Claims

1. A method for controlling a robot, comprising:

defining a target for a motion of the robot;

supplying the target to a whole body motion control unit and a collision avoidance control unit;

combining a joint velocity vector calculated by the whole body motion control unit with a joint velocity vector calculated by the collision avoidance control unit in a blending control unit;

outputting a combined joint velocity vector by the blending control unit;

calculating a distance between different segments of the robot connected to each other via at least one joint or a segment of the robot and another object by a distance computation unit based on the combined joint velocity vector;

submitting the computed distance information to the collision avoidance control unit, the whole body motion control unit and the blending control unit;

calculating a final joint velocity vector {dot over (q)} by {dot over (q)}={1−

f(d)}{dot over (q)}_control+f(d){dot over (q)}_ca wherein {dot over (q)}_control is the joint velocity vector calculated by the whole body motion control unit, {dot over (q)}_ca is the joint velocity vector calculated by the collision avoidance control unit, f(d) representing a function of a shortest distance between segments, wherein the result of function f(d) decides whether the collision avoidance control unit takes over controlling of the robot or the whole body motion control unit takes over control of the robot; and

calculating a motion control signal adapted to command the robot to reach the target on the basis of the final joint velocity vector and controlling the robot based on the calculated motion control signal.

2. The method of claim 1, wherein the first gain factor and the second gain factor change gradually to perform a soft task switching between reaching of the target and collision avoidance.

3. The method of claim 2, wherein the collision avoidance unit is activated if d is smaller than d_a.

4. The method of claim 1, wherein f(d) is defined as

5. The method of claim 4, wherein the collision avoidance control unit is deactivated and the robot tracks a trajectory generated by the whole body motion control unit if d is bigger than d_a.

6. The method of claim 4, wherein trajectories computed by the whole body motion unit take into account collision avoidance in nullspace.

7. The method of claim 1, wherein the whole body motion control unit maps a target reaching motion in task space and collision avoidance motion in nullspace.

8. The method of claim 1, wherein the collision avoidance control unit maps a collision avoidance motion in task space and a target reaching motion in nullspace.

9. A non-transitory computer readable storage medium structured to store instructions executable by a processor in a computing device, the instructions, when executed cause the processor to:

define a target for a motion of a robot;

supply the target to a whole body motion control unit and a collision avoidance control unit;

combine a joint velocity vector calculated by the whole body motion control unit with a joint velocity vector calculated by the collision avoidance control unit in a blending control unit;

output a combined joint velocity vector by the blending control unit;

calculate a distance between different segments of the robot connected to each other via at least one joint or a segment of the robot and another object by a distance computation unit based on the combined joint velocity vector;

submit the computed distance information to the collision avoidance control unit, the whole body motion control unit and the blending control unit;

calculate a final joint velocity vector {dot over (q)} by {dot over (q)}={1−

f(d)}{dot over (q)}_control+f(d){dot over (q)}_ca wherein {dot over (q)}_control is the joint velocity vector calculated by the whole body motion control unit, {dot over (q)}_ca is the joint velocity vector calculated by the collision avoidance control unit, f(d) representing a function of a shortest distance between segments, wherein the result of function f(d) decides whether the collision avoidance control unit takes over controlling of the robot or the whole body motion control unit takes over control of the robot; and

calculate a motion control signal adapted to command the robot to reach the target on the basis of the final joint velocity vector and controlling the robot based on the calculated motion control signal.

10. The computer readable storage medium of claim 9, wherein f(d) is defined as

11. The computer readable storage medium of claim 10, wherein the collision avoidance control unit is deactivated and the robot tracks a trajectory generated by the whole body motion control unit if d is bigger than d_a.

12. The method of claim 10, wherein the collision avoidance unit is activated if d is smaller than d_a.

13. The method of claim 9, wherein trajectories computed by the whole body motion unit take into account collision avoidance in nullspace.

14. The method of claim 9, wherein the whole body motion control unit maps a target reaching motion in task space and collision avoidance motion in nullspace.

15. The method of claim 9, wherein the collision avoidance control unit maps a collision avoidance motion in task space and a target reaching motion in nullspace.

16. A motion control unit in a robot, comprising:

a whole body motion control unit;

a collision avoidance unit;

a blending control unit adapted to;

combine a joint velocity vector calculated by the whole body control unit with a joint velocity vector calculated by the collision avoidance control unit; and

output a combined joint velocity vector;

submit the computed distance information to the collision avoidance control unit, the whole body motion control unit and the blending control unit; and

a distance computing unit adapted to calculate a distance between different segments of the robot connected to each other via at least one joint or a segment of the robot and another object based on the combined joint velocity vector and submit the computed distance information to the collision avoidance control unit, the whole body motion control unit and the blending unit;

wherein the whole body motion control unit is adapted to;

define a target for a motion of the robot;

supply the target to a whole body motion control unit and a collision avoidance unit control;

combine a joint velocity vector calculated by the whole body motion control unit with a joint velocity vector calculated by the collision avoidance control unit in a blending unit;

output a combined joint velocity vector by the blending unit;

calculate a distance between different segments of the robot connected to each other via at least one joint, or a segment of the robot and another object, by a distance computing unit based on the combined joint velocity vector;

submit the computed distance information to the collision avoidance control unit, the whole body motion control unit and the blending unit;

calculate a final joint velocity vector {dot over (q)} by {dot over (q)}={1−

f(d)}{dot over (q)}_control+f(d){dot over (q)}_ca wherein {dot over (q)}_control is the joint velocity vector calculated by the whole body motion control unit, {dot over (q)}_ca is the joint velocity vector calculated by the collision avoidance control unit, f(d) represents a function of a shortest distance between segments, wherein the result of function f(d) decides whether the collision avoidance control unit takes over controlling of the robot, or whether the whole body motion control unit takes over control of the robot;

calculate a motion control signal adapted to command the robot to reach the target on the basis of the final joint velocity vector and controlling the robot based on the calculated motion control signal.

17. The motion control unit of claim 16, wherein f(d) is defined as

18. The motion control unit of claim 17, wherein the collision avoidance control unit is deactivated and the robot tracks a trajectory generated by the whole body motion control unit if d is bigger than d_a.

19. The motion control unit of claim 16, wherein trajectories computed by the whole body motion unit take into account collision avoidance in nullspace.

20. A robot having a motion control unit for avoiding collision, comprising:

a whole body motion control unit;

a collision avoidance unit control;

a blending unit combining a joint velocity vector calculated by the whole body motion control unit with a joint velocity vector calculated by the collision avoidance control unit, and outputting a combined joint velocity vector;

a distance computing module adapted to calculate a distance between two different segments of the robot connected to each other via at least one joint or a segment of the robot and another object based on the combined joint velocity vector, and submit the computed distance information to the collision avoidance control unit, the whole body motion control unit and the blending unit; and

wherein the motion control unit is adapted to;

define a target for a motion of the robot;

supply the target to a whole body motion control unit and a collision avoidance unit control;

combine a joint velocity vector calculated by the whole body motion control unit with a joint velocity vector calculated by the collision avoidance control unit in a blending unit;

output a combined joint velocity vector by the blending unit;

calculate a distance between different segments of the robot connected to each other via at least one joint, or a segment of the robot and another object, by a distance computing unit based on the combined joint velocity vector;

submit the computed distance information to the collision avoidance control unit, the whole body motion control unit and the blending unit;

calculate a final joint velocity vector {dot over (q)} by {dot over (q)}={1−

f(d)}{dot over (q)}_control+f(d){dot over (q)}_ca wherein {dot over (q)}_control is the joint velocity vector calculated by the whole body motion control unit, {dot over (q)}_ca is the joint velocity vector calculated by the collision avoidance control unit, f(d) represents a function of a shortest distance between segments, wherein the result of function f(d) decides whether the collision avoidance control unit takes over controlling of the robot, or whether the whole body motion control unit takes over control of the robot;

calculate a motion control signal adapted to command the robot to reach the target on the basis of the final joint velocity vector and controlling the robot based on the calculated motion control signal.