Robust Flight Control Design with Handling Qualities Incorporation via Low Order Model Matching

In this paper, a robust pitch rate control design for longitudinal aircraft motion based on μ-synthesis is presented. A Linear Fractional Transformation (LFT) uncertainty model is first derived for robust synthesis. The uncertainty dealt with is of parametric nature and represents the variations of weight and center of gravity in the aircraft models. A controller is then developed and tested on the full longitudinal model of the Challenger 604 aircraft provided by Bombardier Aerospace Inc. The model includes both short-period and phugoïd modes of the aircraft, the stick, the actuator and the sensors. It is shown that the controller guarantees desired performance with predicted Level 1 handling qualities under varying weight and center of gravity locations.