On the modeling of asymmetric disturbance effect and rejection control for fixed-wing aircraft

In this paper, the fixed-wing aircraft asymmetric disturbance effect modeling and closed-loop control system evaluation are considered. The asymmetric disturbance is accurately modeled by a combination of the consideration of inertial parameter variation and realistic aerodynamic characteristics of asymmetric configuration generated by the computational fluid dynamics (CFD) simulation. To analyze the impacts of the asymmetric disturbance on the aircraft, two flight control methodologies are compared. Besides the classic and widely implemented PID controller, an uncertainty and disturbance estimator (UDE)-based controller is additionally designed to deal with the asymmetric disturbance. Comparative simulation results are provided to show that: (1) the performance of PID control degrades significantly under asymmetric disturbances; and (2) the UDE-based controller is capable of dynamically compensating for the disturbance thus delivering better trajectory tracking performance than PID controller.