Robots with Collision Avoidance Functionality

• US 20080234864A1
• Filed: 03/20/2008
• Published: 09/25/2008
• Est. Priority Date: 03/23/2007
• Status: Active Grant

• Current Assignee: Arriver Software AB (Qualcomm, Inc.)
• Original Assignee: Honda Research Institute Europe GmbH (Honda Motor Company)
• Inventors: Gienger, Michael, Sugiura, Hisashi, Janssen, Herbert
• Granted Patent: US 8,311,731 B2
• Time in Patent Office: Days
• US Class Current: 700/255
• 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;

calculating a motion control signal adapted to command the robot to reach the target;

calculating a collision avoidance control signal based on closest points of different segments of the robot connected to each other via at least one joint or closest points of a segment of the robot and another object;

assigning weights to the motion control signal and the collision avoidance control signal to generate a weighted motion control signal and a weighted collision avoidance control signal, a weight of the motion control signal assigned a higher value responsive to risk of collision being lower, a weight of the collision avoidance control signal assigned a higher value responsive to the risk of collision being higher;

combining the weighted motion control signal and the weighted collision avoidance control signal to generate a combined weighted signal; and

controlling a motion of the robot according to the combined weighted signal.

2. The method of claim 1, wherein the weight of the motion control output signal and the weight of the collision avoidance control signal change gradually to perform a soft task switching between reaching of the target and collision avoidance.

3. The method of claim 1, wherein calculating a motion control signal comprises:

mapping a collision avoidance motion in null space; and

mapping a target reaching motion in task space.

4. The method of claim 1, wherein the weight of the collision avoidance control signal remains zero when a distance between the closest points are larger than a predetermined distance.

5. The method of claim 1, further comprising performing collision avoidance control by controlling the robot to move the segment of the robot in a direction parallel to a line connecting between the closest points.

6. The method of claim 5, wherein null space of the collision avoidance control is allocated to a motion for reaching the target.

7. A method for controlling a robot to avoid collision, comprising:

calculating 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, and

performing collision avoidance control by controlling the robot to move the segment of the robot in a direction parallel to a line connecting between the closest points.

8. The method of claim 7, wherein performing the collision avoidance control comprises:

mapping a collision avoidance motion in the task space; and

mapping a target reaching motion in null space.

9. A computer program product comprising a 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;

calculate a motion control signal adapted to command the robot to reach the target;

calculate a collision avoidance control signal based on closest points of different segments of the robot connected to each other via at least one joint or closest points of a segment of the robot and another object;

assign weights to the motion control signal and the collision avoidance signal to generate a weighted motion control signal and a weighted collision avoidance signal, a weight of the motion control output signal assigned a higher value responsive to risk of collision being lower, a weight of the collision avoidance control signal assigned a higher value responsive to risk of collision being higher;

combine the weighted motion control signal and the weighted collision avoidance control signal to generate a combined weighted signal; and

control a motion of the robot according to the combined weighted signal.

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

a distance computing module adapted to calculate a collision avoidance control signal based on 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;

a motion control module adapted to calculate a motion control signal commanding the robot to reach a target;

a collision avoidance module adapted to calculate a collision avoidance control signal based on the closest points of different segments of the robot connected to each other via at least one joint or closet points of a segment of the robot and another object; and

a blending control unit adapted to assign weights to the motion control signal and the collision avoidance control signal to generate weighted motion control signal and a weighted collision avoidance signal, a weight of the motion control signal assigned a higher value responsive to risk of collision being lower, a weight of the collision avoidance control signal assigned a higher value responsive to the risk of collision being higher, the blending control unit further adapted to combine the motion control signal and the weighted collision avoidance control signal to generate a combined weighted signal according to which a motion of the robot is controlled.

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

a distance computing module adapted to calculate two closest points of different segments of the robot connected to each other via at least one joint or closest points of a segment of the robot and another object; and

a motion control module adapted to perform collision avoidance control by controlling the robot to move the segment of the robot in a direction parallel to a line connecting between the closest points.