Robot system and method for controlling same

Patent metadata

Field	Value
Publication number	US-2023286145-A1
Application number	US-202318173137-A
Country	US
Kind code	A1
Filing date	Feb 23, 2023
Priority date	Mar 11, 2022
Publication date	Sep 14, 2023
Grant date	—

Abstract

A technique automates robotic assembly of two parts with a fastener structure including an engaging portion and a receiving portion. A robot system includes a robot that grips a workpiece, a force sensor located on the robot to measure a force and a moment acting on the workpiece, and a controller that controls the robot. The controller monitors, while moving the workpiece in a direction along a first axis and inserting the workpiece into a part, a change in a force F in the direction along the first axis and a change in a moment M about a second axis perpendicular to the first axis measured by the force sensor to determine a state of assembly of the workpiece with the part.

First claim

1 . A robot system for inserting a workpiece including an engagement portion into a part including a receiving portion corresponding to the engagement portion to assemble the workpiece with the part, the robot system comprising:
a robot configured to grip the workpiece; a force sensor located on the robot to measure a force and a moment acting on the workpiece; and a controller configured to control the robot, wherein the controller monitors, while moving the workpiece in a direction along a first axis and inserting the workpiece into the part, a change in a force F in the direction along the first axis and a change in a moment M about a second axis perpendicular to the first axis measured by the force sensor to determine a state of assembly of the workpiece with the part.

2 . The robot system according to claim 1 , wherein
the controller determines a state of engagement between the engagement portion and the receiving portion based on the change in the force F.

3 . The robot system according to claim 1 , wherein
the controller determines an appropriateness of an insertion orientation of the workpiece relative to the part based on the moment M.

4 . The robot system according to claim 1 , wherein
the controller determines that the engagement portion and the receiving portion are engaged with each other and that the workpiece is assembled with the part normally in response to a decrease in the force F relative to a maximum value Fmax of the force F recorded at and after a predetermined determination start point exceeding a first threshold.

5 . The robot system according to claim 4 , wherein
the controller determines that the workpiece is assembled with the part normally in response to the moment M being less than a second threshold and a predetermined time elapsing from the predetermined determination start point before the decrease in the force F relative to the maximum value Fmax of the force F exceeding the first threshold.

6 . The robot system according to claim 5 , wherein
the controller determines that assembly of the workpiece is unsuccessful in response to the moment M remaining greater than or equal to the second threshold and the predetermined time elapsing from the predetermined determination start point before the decrease in the force F relative to the maximum value Fmax of the force F exceeding the first threshold.

7 . The robot system according to claim 5 , wherein
the predetermined time is set based on a time taken for the workpiece to reach an insertion end position from the predetermined determination start point.

8 . The robot system according to claim 5 , wherein
the controller performs a recovery operation to correct an insertion orientation of the workpiece in response to the moment M being greater than or equal to the second threshold before the decrease in the force F relative to the maximum value Fmax of the force F exceeding the first threshold.

9 . The robot system according to claim 8 , wherein
the recovery operation includes rotating the workpiece in a direction to reduce the moment M.

10 . The robot system according to claim 8 , wherein
the recovery operation includes moving the workpiece in a direction opposite to an insertion direction of the workpiece.

11 . A method for controlling a robot system for inserting a workpiece including an engagement portion into a part including a receiving portion corresponding to the engagement portion to assemble the workpiece with the part, the method comprising:
controlling a robot gripping the workpiece to move the workpiece in a direction along a first axis and insert the workpiece into the part; measuring a force F in the direction along the first axis and a moment M about a second axis perpendicular to the first axis using a force sensor located on the robot; and determining a state of assembly of the workpiece with the part by monitoring a change in the force F and a change in the moment M while inserting the workpiece.

Assignees

• Omron Tateisi Electronics Co

Inventors

• Liu Zhiqiang
• Tsuchihashi Yuki
• Murai Masahiro

Classifications

• B25J9/1687 Primary

  Assembly, peg and hole, palletising, straight line, weaving pattern movement · CPC title

• G05B2219/40032

  Peg and hole insertion, mating and joining, remote center compliance · CPC title

• B25J9/1633 Primary

  compliant, force, torque control, e.g. combined with position control · CPC title

• B25J13/082

  Grasping-force detectors (in general G01L5/16, G01L5/22) · CPC title

• B25J19/02 Primary

  Sensing devices · CPC title