Lateral Guidance & Control Design for an Unmanned Aerial Vehicle

Abstract This paper presents guidance and control design for a UAV, and its six degrees-of-freedom nonlinear simulation results. The paper focuses on the lateral control and guidance aspects; longitudinal control aspects will be addressed separately in another paper. An introduction to the lateral mission, and guidance problem is given first. Waypoints for straight and turning flight paths are defined. Computation of various flight path parameters is discussed, including formulae for down-range (distance travelled along the desired track), cross-track deviation and heading error of the vehicle; these are then used in the lateral guidance algorithm. The lateral guidance law is then presented, followed by the design of a multivariable H ∞ controller for roll control and stability augmentation. The controller uses the ailerons and rudder for control. The reference roll angle is provided by the guidance law. The sensors available on-board the vehicle do not measure yaw-rate, hence a practical method of its estimation is proposed. The entire guidance and control scheme is implemented on a full nonlinear six degrees-of-freedom simulation of the vehicle. Simulation results are presented and discussed.