Actuator dynamics augmented DOBC for a small fixed wing UAV

This paper presents an actuator dynamics augmentation of the classical Disturbance Observer Based Control (DOBC) approach for control of a small fixed wing Unmanned Aerial Vehcile (UAV). The proposed method modifies the observer to include actuator dynamics. This augmentation allows for significantly higher observer gains in practice than traditional DOBC in the presence of actuator dynamics, resulting in better disturbance rejection performance. The actuator states are unmeasurable, so are also estimated by the proposed observer using an actuator model and the aircraft state. The actuator modelling process of the UAV is provided in detail. The closed-loop stability as well as observer tuning guidelines are discussed. The performance improvement is demonstrated first in numerical simulation and validated with flight test results using a small UAV.