Anti-windup schemes for uncertain nonlinear systems

Several processes are nonlinear and operate under input constraints. Their effective control requires model-based techniques whose performance is ofte n affected by modelling uncertainties. The paper addresses the control of s ingle-input single-output nonlinear systems with input constraints in the p resence of modelling errors. A nonlinear internal model control based on in put output linearisation is designed, and an internal model control with an tiwindup which removes the nonlinear mismatch due to input constraints is g iven. An adaptive internal model control with anti-windup to account for pa rameter uncertainty and an augmented internal model control with anti-windu p to attenuate the effect of modelling errors, are proposed and analysed th eoretically. Simulation results on temperature control of a continuous stir red tank reactor demonstrate the benefits of the proposed anti-windup schem es.