Fixed-time integral sliding mode control for admittance control of a robot manipulator

Yuzhu Sun, Mien Van*, Stephen McIlvanna, Seán McLoone, Dariusz Ceglarek

*Corresponding author for this work

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This article proposes a novel fixed-time integral sliding mode controller for admittance control to enhance physical human-robot collaboration. The proposed method combines the benefits of compliance to external forces of admittance control and high robustness to uncertainties of integral sliding mode control (ISMC), such that the system can collaborate with a human partner in an uncertain environment effectively. First, a fixed-time sliding surface is applied in the ISMC to make the tracking error of the system converge within a fixed time regardless of the initial condition. Then, a fixed-time backstepping controller (BSP) is integrated into the ISMC as the nominal controller to realize global fixed-time convergence. Furthermore, to overcome the singularity problem, a nonsingular fixed-time sliding surface is designed and integrated into the controller, which is useful for practical application. Finally, the proposed controller is validated for a two-link robot manipulator with uncertainties and external human forces. The results show that the proposed controller is superior in the sense of both tracking error and convergence time, and at the same time, can comply with human motion in a shared workspace.

Original languageEnglish
Number of pages17
JournalInternational journal of robust and nonlinear control
Early online date25 Dec 2023
Publication statusEarly online date - 25 Dec 2023


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