Accelerometer to monitor movement of a tool assembly attached to a robot end effector

• US 20060178775A1
• Filed: 02/04/2005
• Published: 08/10/2006
• Est. Priority Date: 02/04/2005
• Status: Abandoned Application

• Current Assignee: ABB Research Ltd. (ABB Limited)
• Original Assignee: ABB Research Ltd. (ABB Limited)
• Inventors: Sun, YunQuan, Zhang, Hui, Wang, Jianjun, Zhang, George, Gan, Zhongxue, Rossano, Gregory F.
• Application Number:
  US11/051,383
• Publication Number:
  US 20060178775A1
• Time in Patent Office: Days
• US Class Current: 700/245
• CPC Class Codes: B25J 13/02 Hand grip control means handles or pedals for crane control B66C13/56; for measuring the force applied to control members G01L5/22; hand-held casings for switching devices, e.g. joy-sticks H01H9/0214
• CPC Class Codes: B25J 9/0081 with master teach-in means
• CPC Class Codes: B25J 9/1674 characterised by safety, monitoring, diagnostic
• CPC Class Codes: G05B 2219/36473 Prohibit teaching if force, speed, acceleration of end effector is out of safe range
• CPC Class Codes: G05B 2219/40547 End effector position using accelerometers in tip
• CPC Class Codes: G05B 2219/40549 Acceleration of end effector

Abstract

An accelerometer is mounted on a robot to monitor movement of a tool assembly attached to the robot end effector for safety monitoring purposes. The accelerometer provides an output signal to the robot controller which the controller uses to monitor the robot movement and stop that movement when a predetermined values of acceleration, speed and distance are detected during lead-through teaching of the robot. A handle can be attached to the robot end effector and the accelerometer can be mounted on the handle.

Claims

1. An industrial robot comprising:

an accelerometer mounted on said robot for monitoring movement of a tool assembly attached to an end effector of said robot for safety monitoring purposes; and

a controller connected to said robot to stop movement of said robot when said controller determines from a signal from said accelerometer that one or more predetermined criteria related to robot acceleration are detected during lead-through teaching of said robot.

3. The industrial robot of claim 1 wherein said accelerometer is mounted on a handle attached to said robot end effector.

4. The industrial robot of claim 3 wherein said handle attached to said robot end effector comprises:

a deadman switch;

means for stopping said robot in an emergency;

means for communicating with said controller connected to said industrial robot; and

either a space mouse or a force sensor.

5. The industrial robot of claim 1 wherein said robot further comprises:

a fully adjustable device to permit scalable translation and orientation movement of said end effector during lead-through teaching of said robot.

9. The industrial robot of claim 5 wherein said fully adjustable device to permit scalable translation and orientation movement of said end effector during lead-through teaching of said robot is a potentiometer or a dial.

10. The industrial robot of claim 3 wherein both a space mouse and a force sensor are mounted on said handle and an input is provided to said controller during lead-through teaching of said robot combined from signals from said force sensor and space mouse and a signal representative of the speed of said robot.

2. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

11. A method for monitoring an industrial robot for safety during lead-through teaching of said robot comprising:

mounting an accelerometer on said robot to monitor movement of a tool assembly attached to an end effector of said robot; and

stopping motion of said robot responsive to said tool assembly movement exceeding a predetermined criteria during said lead-through teaching of said robot.

12. The method of claim 11 further comprising:

determining actual acceleration of said tool assembly from acceleration of said tool assembly measured by said accelerometer;

determining if said actual acceleration exceeds an associated predetermined value;

determining in response to said actual acceleration exceeding an associated predetermined value if speed and distance traveled by said tool assembly each exceed an associated predetermined value; and

stopping motion of said robot only in response to said actual acceleration and said speed and distance traveled all simultaneously exceeding their predetermined associated values.

13. The method of claim 12 further comprising determining said actual acceleration of said tool assembly by subtracting gravity from said tool assembly acceleration measured by said accelerometer.

14. The method of claim 12 further comprising resetting said speed and distance values in response to said actual acceleration not exceeding said associated predetermined value.

17. The method of claim 11 further comprising mounting a device on said robot that permits a scalable combination of orientation motion and translation method of said robot during said lead-through teaching.

15. (canceled)

16. (canceled)

18. (canceled)

19. A computer readable medium having instructions for monitoring an industrial robot for safety during lead-through teaching of said robot, said robot having an accelerometer mounted on said robot to monitor movement of a tool assembly attached to an end effector of said robot, said instructions comprising:

stopping motion of said robot responsive to said tool assembly movement exceeding a predetermined criteria during said lead-through teaching of said robot.

20. The computer readable medium of claim 19 wherein said instructions further comprise:

determining actual acceleration of said tool assembly from acceleration of said tool assembly measured by said accelerometer;

determining if said actual acceleration exceeds an associated predetermined value;

determining in response to said actual acceleration exceeding an associated predetermined value if speed and distance traveled by said tool assembly each exceed an associated predetermined value; and

stopping motion of said robot only in response to said actual acceleration and said speed and distance traveled all simultaneously exceeding their predetermined associated values.

21. The computer readable medium of claim 20 wherein said instructions further comprise:

determining said actual acceleration of said tool assembly by subtracting gravity from said tool assembly acceleration measured by said accelerometer.

22. The computer readable medium of claim 20 wherein said instructions further comprise:

resetting said speed and said distance values in response to said actual acceleration not exceeding said associated predetermined value.

23. A system comprising:

a computing device having executable instructions for monitoring an industrial robot for safety during lead-through teaching of said robot, said robot having an accelerometer mounted on said robot to monitor movement of a tool assembly attached to an end effector of said robot, said executable instructions comprising;

an instruction for stopping motion of said robot responsive to said tool assembly movement exceeding a predetermined criteria during said lead-through teaching of said robot.

24. The system of claim 23 wherein said executable instructions in said computing device further comprise:

executable instructions for;

determining actual acceleration of said tool assembly from acceleration of said tool assembly measured by said accelerometer;

determining if said actual acceleration exceeds an associated predetermined value;

determining in response to said actual acceleration exceeding an associated predetermined value if speed and distance traveled by said tool assembly each exceed an associated predetermined value; and

stopping motion of said robot only in response to said actual acceleration and said speed and distance traveled all simultaneously exceeding their predetermined associated values.

25. The system of claim 24 wherein said executable instructions further comprise:

an executable instruction for determining said actual acceleration of said tool assembly by subtracting gravity from said tool assembly acceleration measured by said accelerometer.

26. The system of claim 24 wherein said executable instructions further comprise:

an executable instruction for resetting said speed and said distance values in response to said actual acceleration not exceeding said associated predetermined value.