Fuzzy event-triggered control of fractional-order non-affine systems subject to unknown control directions, communication limitation, output constraints and input nonlinearities

In this work, a fuzzy event-triggered control strategy has been developed for uncertain nonlinear non-affine non-strict non-commensurate fractional-order (FO) systems (FOSs) subject to unknown control directions, input nonlinearities, communication limitation, event-triggered input, and output constraints. Five kinds of input nonlinearities are considered and general sort of output constraints is addressed. Based on the FO and integer-order (IO) Lyapunov direct theorems, FO Nussbaum function (NF) technique and backstepping method, a novel fuzzy control approach has been proposed, which can overcome the shortcomings of the existing methods. To satisfy the communication limitation, an event-triggering mechanism has been applied. The actuator is protected against the event-triggered input by embedding a filter between the communication channel and actuator. By adding one additional step to the backstepping method, the closed-loop stability has been established in the presence of the filter. Also, to show the avoidance of the Zeno phenomenon, a modified procedure has been proposed. Unlike previous works, the stability is established with no restrictive assumption for the system dynamics . Fuzzy logic systems (FLSs) have been utilized to overcome the non-strict structure, prevent the complexity in the proposed scheme, and estimate virtual controllers derivatives , system unknown dynamics and unknown input nonlinearities. By decreasing the number of adaptive laws for FLSs weight vectors , the computational load has been reduced. It is shown that the system output closely follows the desired signal inside the predefined limits and all closed-loop signals remain bounded. Through three examples, the effectiveness of the proposed control algorithm is illustrated.