Fault-tolerant cooperative tracking control via integral sliding mode control technique

In this paper, we aim to deal with the cooperative tracking problem for a group of nonlinear systems with actuator faults and external disturbance/model uncertainty. The faults in the actuator are allowed to be in arbitrary forms such as actuator degradation, amplification, or even total failure. Moreover, the disturbance/model uncertainty is a Lipschitz one by assuming that the derivative of disturbance/model uncertainty is uniformly bounded. Then, provided that the actuator has sufficient healthy components when the faults happen, we employ the integral sliding mode technique to design the controller that can tolerate the actuator faults, meanwhile the external disturbance can also be rejected. The controller design is separated into two steps. First, a nominal controller is designed such that the estimated disturbance/model uncertainty from disturbance observer is completely rejected and the desired performance is guaranteed. Second, by the integral sliding mode control technique, a compensating controller is designed such that the matched estimation error of actuator faults and the external disturbance/model uncertainty can be compensated. The designed controller, formed by the sum of the nominal controller and compensating controller, proves to guarantee practical synchronization. Simulations demonstrate the effectiveness of our theoretical findings.