A windup prevention scheme for multiple integrating plants allowing for arbitrary reference step inputs

Linear control, designed to obtain a desired disturbance rejection for unstable plants usually causes severe windup problems when input saturation becomes active. These windup effects may reduce the allowable reference signal amplitudes not causing closed loop instability to very small values. Based on a new structure proposed by Teel [12], a windup prevention scheme for multiple integrating plants is developed, which, given a nominal (linear) compensator, allows to apply arbitrary large reference step inputs. A model plant consisting of six integrators is used to demonstrate the results.