ROBOT PARTS ASSEMBLY ON A WORKPIECE MOVING ON AN ASSEMBLY LINE

• US 20110087360A1
• Filed: 03/30/2009
• Published: 04/14/2011
• Est. Priority Date: 03/31/2008
• Status: Active Grant

• Current Assignee: ABB Research Ltd. (ABB Ltd.)
• Original Assignee: ABB Research Ltd. (ABB Ltd.)
• Inventors: Fuhlbrigge, Thomas A., Chen, Heping, Zhang, George
• Granted Patent: US 9,333,654 B2
• Time in Patent Office: Days
• US Class Current: 700/114
• CPC Class Codes: B25J 9/1697 Vision controlled systems
• CPC Class Codes: G05B 2219/39387 Reflex control, follow movement, track face, work, hand, visual servoing
• CPC Class Codes: G05B 2219/40554 Object recognition to track object on conveyor
• CPC Class Codes: G05B 2219/45021 Wheel mounting

Abstract

An industrial robot is used to assemble a part to a predetermined location on a randomly moving workpiece. The workpiece may be an automobile on an assembly line and the part may be a wheel (a tire mounted on a rim) to be assembled on one of the wheel hubs of the automobile. The robot has mounted on it a camera, a force sensor and a gripper to grip the part. After the robot grips the part, signals from both the force sensor and vision are used by a computing device to move the robot to a position where the robot can assemble the part to the predetermined location on the workpiece. The computing device can be the robot controller or a separate device such as a PC that is connected to the controller.

Claims

1. An apparatus for controlling an industrial robot to assemble a part to a predetermined location on a randomly moving workpiece, said robot comprising a force sensor and a vision system both mounted on said robot, said apparatus comprising:

means for causing said robot to grip said part; and

means for simultaneously using signals from said vision system and said force sensor to control movement of said robot to a position where said gripped part can be assembled by said robot to said predetermined location on said randomly moving workpiece.

2. The apparatus of claim 1 further comprising means for using signals from said vision system to determine the position and orientation of said part so that said robot can grip said part.

3. The apparatus of claim 1 further comprising:

means for using signals from said vision system to determine the orientation of said gripped part to the orientation of said predetermined location on said workpiece; and

means for causing, in response to said determination of the orientation of said gripped part to the orientation of said workpiece predetermined location, said robot to reorient said gripped part to match said orientation of said workpiece predetermined location.

4. The apparatus of claim 3 wherein said robot further comprises a tool mounted on said robot to grip said part, said gripping tool having a velocity and means for simultaneously using signals from said vision system and said force sensor to control movement of said robot further comprises:

means for calculating from said vision system signal a velocity error of said moving workpiece and from said force sensor signal a force velocity error; and

means for simultaneously using said calculated velocity errors and said gripper velocity to calculate a reference velocity for said controlled movement of said robot.

5. A method for using an industrial robot to assemble a part to a predetermined location on a randomly moving workpiece comprising:

a. causing said robot to grip said part; and

b. simultaneously using signals from a vision system and a force sensor both mounted on said robot to control movement of said robot to a position where said gripped part can be assembled by said robot to said predetermined location on said randomly moving workpiece.

6. The method of claim 5 further comprising using signals from said vision system to determine the position and orientation of said part so that said robot can grip said part.

7. The method of claim 5 further comprising:

using signals from said vision system to determine the orientation of said gripped part to the orientation of said predetermined location on said workpiece; and

causing, in response to said determination of the orientation of said gripped part to the orientation of said workpiece predetermined location, said robot to reorient said gripped part to match said orientation of said workpiece predetermined location.

8. The method of claim 5 further comprising simultaneously using said signals from said vision system and said force sensor to calculate a reference velocity for said controlled movement of said robot.

9. The method of claim 5 wherein said robot has a gripper mounted on said robot to grip said part, said gripper having a velocity, and said simultaneously using signals from said vision system and said force sensor to control movement of said robot further comprises:

calculating from said vision system signal a velocity error of said moving workpiece and from said force sensor signal a force velocity error; and

simultaneously using said calculated velocity errors and said gripper velocity to calculate a reference velocity for said controlled movement of said robot.

10. A system for controlling an industrial robot to assemble a part to a predetermined location on a randomly moving workpiece comprising:

an industrial robot comprising a force sensor and a vision system both mounted on said robot; and

apparatus connected to said robot for controlling said robot, said apparatus responsive to signals simultaneously from said force sensor and said vision system to control movement of said robot after said robot has gripped said part to a position where said part can be assembled by said robot to said predetermined location on said randomly moving workpiece.

11. A system controlling an industrial robot to assemble a part to a predetermined location on a randomly moving workpiece, said control system comprising:

a computing device having therein program code usable by said computing device, said program code comprising;

code configured to cause said robot to grip said part; and

code configured to simultaneously use signals from a vision system and a force sensor both mounted on said robot to control movement of said robot to a position where said gripped part can be assembled by said robot to said predetermined location on said randomly moving workpiece.

12. A computer program product on a tangible media for controlling an industrial robot to assemble a part to a predetermined location on a randomly moving workpiece, said computer program product comprising:

computer usable program code configured to cause said robot to grip said part; and

computer usable program code configured to simultaneously use signals from a vision system and a force sensor both mounted on said robot to control movement of said robot to a position where said gripped part can be assembled by said robot to said predetermined location on said randomly moving workpiece.