Adaptive Vision-Admittance-Based Leakage-Type Sliding Mode Control for Uncertain Collaborative Robot With Actuator Saturation

In this article, an adaptive vision-admittance-based leakage-type (LT) sliding mode control (SMC) is proposed to solve the uncertain robots’ compliant force control problem with actuator saturation. First, we design the vision-admittance-based model to generate an online reference trajectory concerning the predefined task trajectory and the interaction force command in the image feature space. Second, an adaptive SMC (ASMC) is created to track the generated reference image feature trajectory with high precision. An LT adaptive control law is applied in this controller to overcome the system uncertainties’ impacts in the situation where the upper bound of uncertainty is unknown. Moreover, an auxiliary dynamic term is taken into account in this controller’s design to solve the saturation nonlinearity problem. The feature tracking error can be guaranteed to be convergent according to the Lyapunov stability analysis. Finally, prototype experiments are conducted on a 6-degree-of-freedom (DOF) STEP SD7/700 robot to validate the superiority of the proposed control methodology.