Adaptive fault-tolerant visual control of robot manipulator based on unequal-actuation scheme

This paper presents a novel adaptive visual servo controller for controlling a manipulator with unknown time-varying actuator failure and uncalibrated camera, which allows the output capacity of actuators that drive the same joint different. Since the actuators that drives the same joint in parallel are not identical, an unequal-actuation scheme is given to guarantee that every actuator's output dose not exceed its maximum output capacity. Additionally, to identify the unknown time-varying failure, this paper adopts a widely used actuator failure model to describe the potential failure and proposes a new adaptive law based on Lyapunov's method to compensate the unknown failure. Furthermore, the convergence of the image error and the whole signals in system are proved to be stable. Finally, The simulation results are provided to evaluate the good performance of the proposed controller.