Improved contact stability for admittance control of industrial robots with inverse model compensation

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Date

2024-12-25

Journal Title

Journal ISSN

Volume Title

Publisher

IEEE Xplore

Abstract

Industrial robots have increased payload, repeatability, and reach compared to collaborative robots, however, they have a fixed position controller and low intrinsic admittance. This makes realizing safe contact challenging due to large contact force overshoots in contact transitions and contact instability when the environment and robot dynamics are coupled. To improve safe contact on industrial robots, we propose an admittance controller with inverse model compensation, designed and implemented outside the position controller. By including both the inner loop and outer loop dynamics in its design, the proposed method achieves expanded admittance in terms of increasing both gain and cutoff frequency of the desired admittance. Results from theoretical analyses and experiments on a commercial industrial robot show that the proposed method improves rendering of the desired admittance while maintaining contact stability. We further validate this by conducting actual assembly tasks of plug insertion with fine positioning, switch insertion onto the rail, and colliding the robot end effector with random objects and surfaces, as seen at https://youtu.be/8XfkdHEdWDs.

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Keywords

Industrial robots, Inverse model compensation, Loop dynamics

Citation

Samuel, K., Haninger, K., Haddadin, S., & Oh, S. (2024, October). Improved Contact Stability for Admittance Control of Industrial Robots with Inverse Model Compensation. In 2024 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) (pp. 746-752). IEEE.