Robust Adaptive Nonlinear Admittance Control of Robotic Manipulators With Extra‐Intra Uncertainties and Disturbances

Abstract

ABSTRACT This paper focuses on achieving rapid convergence in finite time for robust trajectory tracking in robotic manipulators with unknown uncertainty bounds. To address the issues of excessive control torque and control reversal at the initial stage, a novel robust adaptive fast terminal sliding mode control (RAF‐TSMC) method is developed. The method ensures faster transient responses and higher steady‐state tracking accuracy and eliminates singularities while mitigating chattering effects. Additionally, to enhance the physical collaboration in human–robot interactions, a nonlinear admittance control method integrated with RAF‐TSMC is developed. Benefiting from adaptive compliance characteristics, this method improves the suppleness and flexibility of a human–robot interaction in uncertain environments. Finally, the effectiveness of the proposed controller is validated using a two‐link robotic manipulator subjected to uncertainties and external forces. The results demonstrate that the proposed RAF‐TSMC controller can effectively minimize tracking errors and convergence time, and the proposed nonlinear admittance control with RAF‐TSMC can enhance the flexibility and adaptability of the robot system.