Structurally Stable Output Regulation Problem With Sampled-Output Measurements Using Fuzzy Immersions

In this paper, a fuzzy nonlinear ripple-free regulator is proposed to solve the sample-data structurally stable regulation problem for the case of nonlinear or generalized immersion. This regulator guarantees asymptotic tracking of time-varying references and rejection of disturbances while maintaining the closed-loop stability. Such a regulator is based on a continuous fuzzy error feedback controller, which updates its states at each sampling period and relies on the existence of an internal model. The internal model is obtained by determining, if possible, an observable generalized immersion of the exosystem dynamics. A key feature is that this immersion allows the generation of all the possible steady-state inputs for all admissible values of the system parameters. The robustness of the proposed fuzzy controller, under parameter uncertainties and changes on disturbance signals, is tested in an illustrative example.