Fuzzy adaptive fault-tolerant output feedback control of multi-input and multi-output non-linear systems in strict-feedback form

This study develops an adaptive fuzzy control method for accommodating actuator faults in a class of uncertain multi-input and multi-output non-linear systems in strict-feedback form and without the requirement of their states being available for controller design. The considered faults are modelled as both loss-of-effectiveness and lock-in-place (stuck at unknown place). With the help of fuzzy logic systems to approximate the unknown non-linear functions, a fuzzy adaptive observer is developed for estimating the unmeasured states. Combining backstepping technique with non-linear tolerant-fault control theory, a novel adaptive fuzzy fault-tolerant control approach is constructed. It is proved that the proposed control approach can guarantee that all the signals of the resulting closed-loop system are bounded, and also the tracking errors between the system outputs and the reference signals converge to a small neighbourhood of zero by appropriate choice of the design parameters. Simulation results are provided to show the effectiveness of the control approach.