Unmanned aerial vehicles (UAVs) are extensively used for defense and surveillance applications. To ensure desirable performance under all conditions, a UAV requires an appropriate control strategy. For the design of control law, a complete understanding of the model is necessary. The present research proposes and develops a control strategy for a three-wheeled UAV while it is in taxi phase. This necessitates conducting a control-oriented analysis on the UAV to determine the most efficient input channel for controlling a specific output. A control structure is then designed to control the outputs using the control input of nose-wheel steering angle and rudder. In this regard, a proportional integral derivative (PID) controller offers a preliminary solution. To cater for the highly nonlinear nature of the taxi model, we propose a solution that employs a gain-scheduled PID (GS-PID) controller to cover the entire operating range of the UAV during taxi phase, where speed of the UAV is a scheduling variable. The values of the controller parameters are continuously updated according to the current UAV speed. Simulation results in the form of trajectory tracking in the presence of disturbances demonstrate efficiency of the proposed control law.

Keywords: Taxi phase, Unmanned aerial vehicle (UAV), Proportional integral derivative (PID), Gain scheduled (GS)