I. Introduction
Fuzzy logic system has been widely used in controlling uncertain nonlinear systems because of its prominent universal approximation ability to deal with the nonstructural or nonparametric uncertainties as pointed out in [1]–[5]. By combining with the typical backstepping adaptation design [6], many significant fuzzy adaptive control schemes have been proposed, see, for example, [7]–[13], [33]–[36], [38]. In practical operation, these fuzzy controllers are usually imposed on the plant through actuator components. However, in some cases [16], [17], such an actuation mechanism may suffer from the failures/faults of getting stuck abruptly or losing partial effectiveness, which easily cause the performance deterioration and even lead to instability of the closed-loop system if the compensation for these failures or faults is not considered in the fuzzy control design. With increasing demands for the safety and reliability in life-critical systems, nowadays, more and more control schemes are required to have an adaptation ability of accommodating actuator failures.