L₁ augmentations for a fixed gain controller on a large transport aircraft

This paper presents a sequential synthesis controller design process, integrating quantitative feedback theory and L₁piecewise constant output-feedback control theory. Quantitative Feedback Technique is used to generate a baseline fixed gain controller, to avoid velocity or dynamic pressure based gain scheduling and provide satisfying performance under nominal conditions. In case of off-nominal conditions, the baseline controller is augmented by L₁piecewise constant output-feedback control laws. Both baseline plant augmentation and the closed-loop augmentation are introduced to eliminate the performance degradation caused by a off-normal dynamics, such as a pitch-up nonlinearity. These two augmentation strategies are compared regarding performance metrics and robust metrics along the entire envelope. Furthermore, actuator dynamics and time delays are taking into account.