Implementation and Testing of a Backstepping Controller Autopilot for Fixed-wing UAVs

The ability of backstepping controllers to deal with nonlinearities make this technique a suitable candidate for the control of small fixed-wing Unmanned Aerial Vehicles (UAVs). The authors have already proposed a comprehensive approach combining backstepping with PID controllers for simultaneous longitudinal and latero-directional control of fixed-wing UAVs, achieving good performance even with considerable levels of signal noise [1]. In further detail, the ability of the mixed approach to control different size and configuration aircraft in the presence of parametric uncertainties or noise, and when implemented on a microcontroller board was demonstrated. The present paper illustrates integration and testing of the backstepping controller on a real unmanned aircraft. After a summarizing the adopted control design and strategy, initial software and hardware simulations validate the control action for the selected aircraft. The implementation of the microcontroller on the aircraft and the integration with other aircraft systems is also illustrated. Experimental results obtained for ground and flight tests are presented, validating the applicability of the backstepping controller.