Adaptive fault-tolerant control for time-delay systems with saturation nonlinearity and L2-disturbances

This paper studies the problem of designing adaptive fault-tolerant H_∞ controllers for linear time-delay systems with actuator saturation. The disturbance tolerance ability of the closed-loop system is measured by an optimal index. A notion of adaptive H_∞ performance index is proposed to describe the disturbance attenuation performances of closed-loop systems. New methods for designing indirect adaptive fault-tolerant controllers via state feedback are presented for actuator fault compensations. Based on the on-line estimation of eventual faults, the adaptive fault-tolerant controller parameters are updating automatically to compensate the fault effects on systems. The designs are developed in the framework of linear matrix inequality (LMI) approach, which can guarantee the disturbance tolerance ability and adaptive H_∞ performances of closed-loop systems in the cases of actuator saturation and actuator failures. An example is given to illustrate the efficiency of the design method.