H2 and H∞ robust autopilot synthesis for longitudinal flight of a special unmanned aerial vehicle: A comparative study

Abstract

The aim of this paper is to investigate the feasibility of robust H 2 and H∞ autopilots to the longitudinal flight motions of a flying wing unmanned aerial vehicle (UAV), P15035, developed by Monash Aerobotics Research Group. The challenge associated with this UAV is related to the fact that all motions are controlled by two independently actuated ailerons, namely elevons, together with its throttle. The scope of this research is nonetheless limited only for elevon control based on the trimmed linear longitudinal flight modes obtained experimentally from the previous study, while the throttle is a constant. Since the real environment is subject to modelling uncertainties and variations, robust H2 and H ∞ control systems are designed to withstand such uncertainties and variations. Simulations indicate that the control systems designed poss acceptable performances both in time and frequency domain, with reasonable settling time and overshoots while maintaining reasonably robust stability. It further shows that robust H∞ autopilot has demonstrated superior time domain performances compared with the H2 counterpart. © 2008 The Institution of Engineering and Technology.