Method of automatically avoiding obstacle for arm robot and control device

Patent metadata

Field	Value
Publication number	US-10350756-B2
Application number	US-201415539838-A
Country	US
Kind code	B2
Filing date	Dec 25, 2014
Priority date	Dec 25, 2014
Publication date	Jul 16, 2019
Grant date	Jul 16, 2019

Abstract

Method of automatically avoiding an obstacle for a robot including a geometric model expression step, an area setting step, a final posture deciding step, an initial route deciding step, a virtual posture calculation step, an interference determining step, a way-point posture deciding step that decides the virtual posture as a way-point posture; and when the geometric model is determined to interfere with the no-entry area, virtually generates a repulsive force for relatively repelling an interfering portion of the geometric model from an interfering portion of the no-entry area, calculates a posture in a state where the interfering portion of the model is pushed from the no-entry area into the operating area by the repulsive force, and decides the calculated posture as a way-point posture; an updated route deciding step, and a step repeatedly performing the steps from the initial route deciding step to the updated route deciding step.

First claim

What is claimed is:

1. A method of automatically avoiding an obstacle for an arm robot having a robotic arm to which a plurality of links are coupled by joints and to which a hand is provided in a tip-end part thereof, comprising:
modeling the robot so as to have a geometric shape and expressing the model as a geometric model;
setting a no-entry area into which the geometric model is not to enter, and an operating area, that is defined by the no-entry area and where the geometric model operates;
deciding a final posture of the robot;
deciding an initial route of the hand when the robot changes from the current posture toward the final posture;
calculating a virtual posture of the robot corresponding to a given point on the initial route;
determining whether the geometric model in the virtual posture interferes with the no-entry area;
deciding, when the determining the interference determines that the geometric model does not interfere with the no-entry area, the virtual posture as a way-point posture, and when the determining the interference determines that the geometric model interferes with the no-entry area, virtually generating a repulsive force for relatively repelling an interfering portion of the geometric model from an interfering portion of the no-entry area, calculating a posture in a state where the interfering portion of the geometric model is pushed out from the no-entry area into the operating area by the virtual repulsive force, and deciding the calculated posture as a way-point posture;
deciding a route of the hand when the posture changes from the current posture to the final posture via the way-point posture, as an updated route; and
repeatedly performing the deciding the initial route, the calculating the virtual posture, the determining the interference, the deciding the way-point posture, and the deciding the updated route, under an assumption of the latest way-point posture decided in the deciding the way-point posture being the current posture in the deciding the initial route.

2. The method of claim 1 , wherein the deciding the final posture includes selecting from the plurality of final posture candidates of the robot set on a known route and deciding as the final posture, a final posture candidate of which a sum total of absolute values of displacements in an angle of each of the joints between the current posture and the final posture candidate of the robot is minimum.

3. The method of claim 1 , wherein the deciding the way-point posture includes:
calculating a torque produced by the virtual repulsive force on a rotational shaft of each of the joints of the robot in a certain virtual posture;
further calculating a change with time of the virtual posture of the robot by repeatedly performing a calculation of the virtual posture of the robot after a given period of time that changes due to an influence of the torque, by using the virtual posture as the origin; and
deciding the way-point posture based on the virtual posture of the robot when the change with time of the virtual posture of the robot is converged.

4. The method of claim 1 , wherein the virtual repulsive force increases in proportion to a distance of the geometric model entering into the no-entry area.

5. The method of claim 1 , comprising:
determining whether the change with time of the posture of the robot does not approach the final posture, and the posture falls into a halt state;
generating, when the posture is determined to fall into the halt state in the determining the halt state, a way-point posture candidate other than the posture in the state where the model is pushed out by the virtual repulsive force of the robot;
firstly determining whether the way-point posture candidate is a posture that approaches the final posture; and
firstly deciding, when the way-point posture candidate is determined to be the posture that changes in a direction approaching the final posture in the first determination, the way-point posture based on the way-point posture candidate.

6. The method of claim 5 , comprising:
secondly determining, when the way-point posture candidate is determined to be a posture that changes in a direction of separating from the final posture in the first determination, whether the way-point posture candidate is selected based on a probability value; and
secondly deciding, when the way-point posture candidate is determined to be selected in the second determination, the way-point posture based on the selected way-point posture candidate.

7. A control device of an arm robot having a robotic arm to which a plurality of links are coupled by joints and to which a hand is provided in a tip-end part thereof, comprising:
a geometric model expresser configured to model the robot so as to have a geometric shape and express the model as a geometric model;
an area setter configured to set a no-entry area into which the geometric model is not to enter, and an operating area, that is defined by the no-entry area and where the geometric model operates;
a final posture decider configured to decide a final posture of the robot;
an initial route decider configured to decide an initial route of the hand when the robot changes from the current posture toward the final posture;
a virtual posture calculator configured to calculate a virtual posture of the robot corresponding to a given point on the initial route;
an interference determinator configured to determine whether the geometric model in the virtual posture interferes with the no-entry area;
a way-point posture decider configured to decide a way-point posture; and
an updated route decider,
wherein the way-point posture decider decides, when the interference determinator determines that the geometric model does not interfere with the no-entry area, the virtual posture as the way-point posture, and when the interference determinator determines that the geometric model interferes with the no-entry area, the way-point posture decider virtually generates a repulsive force for relatively repelling an interfering portion of the geometric model from an interfering portion of the no-entry area, and the way-point posture decider calculates a posture in a state where the interfering portion of the geometric model is pushed out from the no-entry area into the operating area by the virtual repulsive force, and decides the calculated posture as the way-point posture,
wherein the updated route decider decides a route of the hand when the posture changes from the current posture to the final posture via the way-point posture, as an updated route, and
wherein the initial route decider, the virtual posture calculator, the interference determinator, the way-point posture decider, and the updated route decider process repeatedly under an assumption of the latest way-point posture decided by the way-point posture decider being the current posture of the initial route decider.

Assignees

• Kawasaki Heavy Ind Ltd

Inventors

• Nakaya Atsushi
• Yoshida Masaya
• Mase Shohei
• Takahashi Hiroki

Classifications

• H10P72/7602

  the wafers being placed on a robot blade or gripped by a gripper for conveyance · CPC title

• B25J9/1666 Primary

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• B25J9/06

  characterised by multi-articulated arms · CPC title

• B25J9/1664

  characterised by motion, path, trajectory planning · CPC title

• H01L21/68707

  Electricity · mapped topic