A sliding mode control scheme for non-minimum phase non-linear uncertain input-delay chemical processes

Abstract

This paper considers the robust control of non-linear uncertain chemical processes in the presence of input-delay and inverse response. A novel and systematic sliding mode control (SMC) scheme, which integrates a time-advanced non-linear predictor and a statically equivalent output map (SEOM), is proposed to compensate for the process’s input-delay and to circumvent the negative effect of inverse response. A Lyapunov-based approach is utilized to ensure the robust control performance of the proposed SMC system. To demonstrate the effectiveness and applicability of the SMC control strategy, we applied it to the regulation control of a Van de Vusse reactor in the presence of input-delay, non-minimum phase behavior, and diversified uncertainties such as unmodeled side reaction, measuring error, parameter uncertainties, and/or extra unmeasured disturbances. The potential use of a sliding observer along with the proposed scheme is also investigated in this work. Extensive simulation results reveal that the proposed SMC design methodology is applicable and promising for the robust control of non-linear, uncertain, non-minimum phase, time-delay chemical processes.