Linear Tracking Control for Small-Scale Unmanned Helicopters

This paper presents a model-based tracking control design for small-scale unmanned helicopters. The design objective is for the helicopter to track predefined inertial position (or velocity) and heading reference trajectories. The controller is based on a nominal linear state-space model that successfully captures the small-scale helicopter coupled multivariable dynamics. The flight controller is composed of two feedback loops that regulate the tracking error of the longitudinal-lateral and heading-heave motion of the helicopter, respectively. The tracking error is determined by constructing a reference state generator based on the linear helicopter model and the reference outputs. The state generator can be systematically designed using the backstepping approach for systems in feedback form and by applying a physically meaningful approximation to the linear helicopter model. The controller performance is successfully tested using a realistic flight simulator.