Improved Design and Implementation of Automatic Flight Control System (AFCS) for a Fixed Wing Small UAV

Abstract

This paper presents an implementation of automatic flight control system (AFCS); analyzes and assures its performance during model in loop (MIL), software in loop (SIL), and processor in loop (PIL) stages. Based on both linear and analytic linear models with trimmed values of straight and leveling scenario, the proposed autopilot is applied to an Ultrastick-25e fixed wing unmanned aerial vehicle (UAV). The implementation of Ultrastick-25e AFCS is accomplished according to the resulted design parameters, and performing various flight scenarios. The choice of avionics and sensors of small UAV (SUAV) required for stability based on commercial off the Shelf (COTS) components. The proposed design uses low cost and light weight micro electro mechanical systems (MEMS) as new sensor technology. Since MEMS suffers from various types of noise, state estimation technique is introduced using both Kalman filter (KF) and complementary filter. Moreover, both results of KF and complementary filter are compared. Finally, PIL simulation is implemented to evaluate the autopilot as hardware components and software algorithms for management and PID control structure with its parameters proposed for implementing AFCS. The results show a good performance in disturbance rejection and robustness against sensors noise.