Method and system for appraising the wear of axes of a robot arm

• US 20050278148A1
• Filed: 06/15/2005
• Published: 12/15/2005
• Est. Priority Date: 06/15/2004
• Status: Active Grant

• Current Assignee: ABB Patent GmbH (ABB Limited)
• Original Assignee: ABB Patent GmbH (ABB Limited)
• Inventors: Hansen, Sven, Schmidt, Steffen, Henrich, Kim, Bader, Axel
• Granted Patent: US 7,643,946 B2
• Time in Patent Office: Days
• US Class Current: 702/183
• CPC Class Codes: B25J 9/1641 compensation for backlash, friction, compliance, elasticity in the joints
• CPC Class Codes: G05B 2219/50197 Signature analysis, store working conditions, compare with actual

Abstract

A method determines the wear of axes of a robot arm of an industrial robot. A torque profile of at least one axis taken during at least one working cycle of the industrial robot is used as a basis for an analysis. The torque profile is analyzed for portions of the torque profile that exceed a previously fixed torque band, and current axial wear is determined by assessing the frequency and/or the curve profile of the portions of the torque profile. A system is provided for determining the wear.

Claims

1. A method for appraising wear of axes of a robot arm of an industrial robot, which comprises the steps of:

taking a torque profile at at least one axis during at least one working cycle of the industrial robot as a basis for an analysis;

analyzing the torque profile for portions of the torque profile that leave a previously fixed torque band; and

determining current axial wear by assessing a frequency and/or a curve profile of the portions of the torque profile.

2. The method according to claim 1, which further comprises performing one of:

measuring the torque profile; and

reading out the torque profile from a data memory.

3. The method according to claim 1, which further comprises analyzing a ratio of a maximum torque value in a specific portion of the torque profile to an averaged torque value in a previously defined time period within the working cycle considered for assessing the axial wear.

4. The method according to claim 1, which further comprises analyzing at least one curve profile of a portion of the torque profile for assessing the axial wear.

5. The method according to claim 1, which further comprises using axis-specific parameters for assessing the axial wear.

6. The method according to claim 5, which further comprises determining the axis-specific parameters empirically or by a neural method.

7. The method according to claim 1, which further comprises representing at least one of the torque profiles and a torque band on a display device.

8. The method according to claim 1, which further comprises appraising an absolute axial wear or axial state by taking into account the current axial wear together with a number of working cycles completed so far.

9. The method according to claim 1, which further comprises estimating a time period until a wear limit for the axis is reached by taking into account the current axial wear and/or a number of working cycles completed so far.

10. The method according to claim 5, which further comprises selecting the axis-specific parameters from the group consisting of a type of motor of a drive motor of an axis, a size of motor of a drive motor of an axis, a transmission of an axis and a transmission backlash.

11. The method according to claim 4, which further comprises analyzing a slope of the curve profile at a time directly before and possibly after an extreme, taken from the latter up to at least a next-following point of inflection of the curve profile.

12. A system for determining wear of axes of a robot arm of an industrial robot, comprising:

a data module containing data of a torque profile of at least one axis during at least one working cycle of the industrial robot;

an analysis module for selecting portions of the torque profile that exceed a previously fixed torque band; and

an assessment module for interpreting a frequency and/or a curve profile of the portions of the torque profile as axial wear, said assessment module, said data module, and said analysis module coupled to each other for exchanging the data with each other.

13. The system according to claim 12, wherein at least one of said data module, said analysis module and said assessment module, is disposed in a robot controller.

14. The system according to claim 12, further comprising an evaluation device to be connected to a robot controller, at least one of said data module, said analysis module and said assessment module is disposed in said evaluation device.

15. The system according to claim 12, wherein the torque profile can be read out from a robot controller as direct or indirect values.

16. The system according to claim 12, wherein said data module, said analysis module and said assessment module are in each case computer program products.