Enhancing constant force tracking in uncertain contact surfaces: An admittance controller utilizing virtual delayed resonator

The lack of precise environmental stiffness information can significantly compromise the accuracy of force control during manipulator contact operations, leading to undesirable jitter effects at the end-effector. To address this issue, a novel admittance control method is proposed in this paper, which employs a virtual delayed resonator to enhance force tracking accuracy and suppress robot jitter. The Takagi–Sugeno (T–S) fuzzy model is developed to mitigate the impact of environmental stiffness errors, as observed by the Extended Kalman Filter (EKF), on system performance. Additionally, the $H_{\infty }$ control strategy, based on Linear Matrix Inequality (LMI), is implemented to ensure system stability under external disturbances. Simulation results demonstrate the effectiveness of the proposed method in achieving consistent force tracking and suppressing chatter. Experimental outcomes further validate that, even when the workpiece stiffness is unknown, the proposed approach effectively reduces jitter at the manipulator’s end-effector while improving force tracking accuracy.