Optimal integral sliding mode control with feedforward compensation for nonlinear systems and its applications

This paper proposes an optimal integral sliding mode control scheme with feedforward compensation for uncertain systems. The uncertain system under consideration may have matched norm bounded uncertainties, and mismatched external persistent disturbance which are generated by an exogenous system. By designing an optimal integral sliding mode surface which includes the state of the exogenous system, an optimal sliding mode control scheme with feedforward compensation is developed to attenuate the mismatched external disturbance. The feedback and feedforward gain matrices can be obtained by solving a Riccati algebraic equation and a Sylvester equation, respectively. It is shown through simulation results of an offshore steel jacket-type platform system that the proposed control scheme is effective to attenuate the external persistent disturbance and thereby improve the performance of the system significantly.