Output-feedback adaptive control for a class of MIMO nonlinear systems with actuator and sensor faults

In this paper, an output-feedback adaptive control scheme is proposed for a class of multi-input multi-output (MIMO) nonlinear systems, aiming at tolerating unknown actuator faults and unknown sensor faults simultaneously. The number of actuator faults is allowed be infinity, while the sensors may suffer from bias and gain variation all the time. By constructing an auxiliary filter and estimating the bounds of the fault uncertainties, the effects of the faults are successfully compressed. Also, the difficulty related to the high-frequency gain matrix is circumvented by introducing a matrix factorization and a similarity transformation. The proposed scheme is able to ensure that all closed-loop signals are globally uniformly bounded and the tracking error converges to a residual set exponentially. Simulation results illustrate the effectiveness of the proposed scheme.