Research on the attitude regulation of 3-DOF hover system

Quadrotor helicopter is emerging as a popular platform for unmanned aerial vehicle research, due to its simplicity of structure and maintenance as well as the capability of hovering and vertical take-off and landing. The attitude controller is an important feature of quadrotor helicopter since it allows the vehicle to keep balance and perform the desired maneuver. In this paper, nonlinear control strategies including active disturbance rejection control (ADRC), sliding mode control (SMC) and backstepping method are studied and implemented to stabilize the attitude of a 3-DOF hover system. ADRC is an error-driven control law, with extended state observer (ESO) estimating the unmodeled inner dynamics and external disturbance to dynamically compensate their impacts. Meanwhile, both backstepping technique and SMC are developed based on the mathematical model, whose stability is ensured by Lyapunov global stability theorem. Furthermore, the performance of each control algorithm is evaluated by experiments. The results validate effectiveness of the strategies for attitude regulation. Finally, the respective characteristics of the three controllers are high-lighted by comparison, and conclusions are drawn on the basis of the theoretical and experimental analysis.