Heading control of a fixed wing UAV using alternate control surfaces

Unmanned Air Vehicles (UAVs) have incredible competencies in forces and civil relevancies. The flight and navigation of a UAV is autonomously controlled by an onboard autopilot. The heading control of a UAV is a vital operation of autopilot, executed by employing a design algorithm that controls its direction and navigation. Commercially available autopilots mostly exploit Proportional-Integral-Derivative (PID) based heading controllers using aileron deflection as the input variable. In this paper, we give a comparison of the performances of two heading-controller design techniques i.e. aileron based heading controller and rudder based heading controller using a Proportional Integral Differential (PID) controller. We have taken a nonlinear model of a small sized UAV-Aerosonde. This model is then linearized around a stable trim point and subsequently decoupled for longitudinal and lateral designs. The small perturbation control theory helps us test the designed controllers with the nonlinear model. The compensated linear and nonlinear models along with their results are presented. Our exploration reveals that rudder based heading controller has intrinsic potency compared to commercially employed aileron based heading controllers for UAV heading control, with regard to better transient response, thus improving the overall response as well as payload performance during a heading change maneuver. The conclusion may show the way to a valuable outcome in autopilot design of UAV.