Double time-scale flight controller design for a small-scale unmanned helicopter

This paper presents a double time-scale flight controller design method for a small unmanned helicopter. Specifically, according to the characteristics of a small unmanned helicopter model and the time-scale separation principle, the fast time-scale attitude control loop is regarded as the inner loop of the entire control system and correspondingly, the slow time-scale translational control loop is chosen as the outer loop. The flight controller is designed by using the back-stepping technique and the quaternion-based description method. The paper utilizes Lyapunov techniques to analyze the stability of the designed closed-loop control system, which prove that the double time-scale flight control system can achieve exponential convergence for the tracking error. Finally, some numerical simulation is implemented, whose results demonstrate that the proposed controller can achieve superior control performance for position tracking control.