Rastreamento global via controle por modos deslizantes e observador com ganho dinamico

a novel output-feedback sliding mode control (smc) strategy is proposed for a class of single-input-singleoutput (siso) uncertain time-varying nonlinear systems for which a norm state estimator can be implemented. such a class encompasses minimum-phase systems with nonlinearities afinely norm bounded by unmeasured states with growth rate depending nonlinearly on the measured system output and on the internal states related with the zero-dynamics. the sliding surface is generated by using the state of a high gain observer (hgo) while a peaking free control amplitude is obtained via norm observer. in contrast to the existing semi-global smc solutions available in the literature for the class of plants considered here, the proposed scheme is free of peaking and achieves global tracking with respect to a small residual set. the key idea is to design a time-varying hgo gain implementable only from measurable signals.