Adaptive Fault-Tolerant Control With Prescribed Tracking Performance For Uncertain Nonlinear Systems Preceded By Prandtl-Ishlinskii Operator

When using smart actuators to drive an uncertain unparametrizable nonlinear system, it is a challenging problem to design such an adaptive controller that the output tracking error can be steered into a preset interval asymptotically, especially in the presence of possible actuator failures which are unknown in time, pattern and value. To overcome the challenge, in the paper, an adaptive control scheme is developed, based on the nonlinear system model of lower-triangular form, and preceded by an unsaturated Prandtl-Ishlinskii hysteresis operator. The techniques of direct adaptive fuzzy control, decomposition of nonlinearities, and backstepping recursive design are used. With our scheme, it can be proved that all closed-loop signals are bounded, and the plant output tracks any given reference signal asymptotically with a user-defined accuracy. These are also illustrated through simulation results.