HOSM driven output tracking in the nonminimum-phase causal nonlinear systems

Asymptotic output tracking in a class of causal nonminimum-phase uncertain nonlinear systems is addressed via higher order sliding modes. Local asymptotic stability of the output tracking-error dynamics is provided. An output reference profile and an external disturbance forcing the internal dynamics are defined by an unknown linear exosystem. Its characteristic polynomial (which is used in the output-tracking control algorithm) is identified online by using a higher order sliding mode parameter observer. The input-output dynamics is compensated by higher order sliding mode (HOSM) control. A numerical example illustrates the performance of the developed HOSM control algorithm.