Variable structure compensators for systems subject to actuator saturation

Most existing actuator saturation compensators are fixed structure with constant parameters. As the linear system with actuator saturation now becomes a non-linear system, using only one linear compensator may not always produce satisfactory response. A variable structure compensator that switches between several linear compensators is proposed in this paper. The choice of the timing and the method to switch compensators is presented, and the stability of the compensated system using variable structure compensators is also discussed. The result is applied to analyze the stability of systems using the limiting integrator or the P-band method. The performance of the proposed variable structure compensators is illustrated by an example.