Performance improvement of saturated system using loop shaping approach

Actuator saturation is an important issue when designing practical control systems. It usually induces the windup phenomenon and even yields system instability. In this paper, a two-stage controller design method is proposed for systems with actuator limitations using the loop shaping approach. In this approach, a pre-designed controller is first used to stabilize the control system to achieve the desired performance. A loop-shaping-based auxiliary controller is then introduced to reduce the windup effect, which might be caused by actuator limitation or functional damage during the mission.