Implementation of adaptive fault-tolerant tracking control for robot manipulators with integral sliding mode

This article presents an adaptive fault-tolerant tracking control for uncertain robot manipulators. By fully considering the effects of uncertainties and actuator effectiveness faults, an integral sliding manifold with a novel auxiliary function is first proposed for tracking control of robot manipulators. Then, a novel fault-tolerant tracking control based on the proposed integral sliding manifold is developed to acquire robustness in both reaching and sliding phase. In order to further reduce the effects of uncertainties on tracking performance, an adaptive law is performed to estimate unknown parameters of the upper bounded uncertainties, which further reduces the control torque input in case of the similar tracking performance. The stability of the proposed approaches is accomplished by Lyapunov stable theory and homogeneous technique. The key contributions of the proposed approach are as follows: (i) the reaching phase of sliding mode control is removed completely in the control design and then the tracking system enters the sliding mode from the initial states; (ii) the nominal control term is eliminated in the design of integral sliding surface and then the algebraic loop problem is also avoided in the proposed approach for robot manipulators; (iii) the simple control structure with an adaptive law is obtained better tracking performance by utilizing lower control torque input and then the effects of time-delay and computational burden are also restrained from the proposed approach. Simulation and experimental comparisons have been accomplished for verifying the effectiveness of the proposed approach.