Adaptive Robust Admittance Control of Robots Using Duality Principle-Based Impedance Selection

The performance of robot admittance control depends heavily on environmental dynamics, the desired impedance selection, and control input. In this study, an adaptive robust admittance control strategy is proposed for robot–environment interaction. The environmental impedance is estimated using an adaptive law with projection modification to guarantee that the impedance estimator is constrained in a predefined set. Then, the desired robot stiffness and damping are determined based on the duality principle. To obtain the desired impedance dynamics, an adaptive robust admittance controller based on time-delay estimation is designed for the robot to track the admittance trajectory with the prescribed performance. Simulations are conducted to show the effectiveness of the environmental impedance estimation and the proposed adaptive robust admittance control.