Attitude Control of Small Electric Helicopter by Using Quaternion Feedback

Abstract

In this study, a nonlinear attitude controller for a small unmanned electric helicopter is designed by using quaternion feedback provided by the backstepping control method. First, a quaternion-based multi-input multi-output(MIMO) nonlinear attitude model of a small helicopter is derived. This nonlinear model consists of three parts, namely, the time derivatives of the quaternion, the Euler equation of rotation, and the flapping dynamics of the main rotor and the stabilizer bar. Next, a nonlinear MIMO controller that calculates the desired torque input by the backstepping control method is designed. The control law is modified to exclude a online computation of time derivatives of sensor output. The controller achieves the asymptotic stability of the origin of the attitude error system, and guarantees that the helicopter could track arbitrary desired attitude. Finally, a simulation and experiment are performed, and the results of this simulation and experiment show the effectiveness of the suggested nonlinear MIMO controller.