Roll Rate Controller Design of Small Fixed Wing UAV using Relay with Embedded Integrator

Small unmanned fixed wing UAVs normally have very complex non linear dynamics. This because of coupling between various axes and several forces acting on the body of aircraft. Due to higher order dynamics, design of controllers becomes very difficult. Therefore, one of the viable methods to use is data from relay based experiments. Identifying dynamics of fixed wing UAV through relay with hysteresis is novel method but it requires few parameters to be set beforehand such as hysteresis value. This work investigates use of relay with integrator where dynamics of a fixed wing UAV can be effectively identified with minimal settings. System response data collected through relay with integrator contains minimal high frequency noise and ensures response information is contained within lower & median frequency range. Hardware based experiments are done to find out critical frequency response points of system by applying frequency sampling filter on relay output data. Afterwards, a PI controller is designed to control roll rate of UAV.