CONTROL-SYSTEM DESIGN ISSUES FOR UNSTABLE LINEAR-SYSTEMS WITH SATURATED INPUTS

The paper studies stable setpoint tracking for linear open-loop unstab le systems with saturated control input. A linear reference filter is introduced that allows the independent design of the prestabilising an d setpoint tracking controllers in an internal model control configura tion. A nonlinear reference conditioning filter is also proposed that avoids saturation in the main control loop, which remains stable there after. Rules of thumb giving bounds on amplitude and frequency for sin usoidal references are given that ensure stable saturated operation of the nonlinear reference filter.