Robust hierarchical control of a laboratory helicopter

This paper deals with the robust position control problem for a three degree-of-freedom (3DOF) laboratory helicopter. The 3DOF helicopter system is a nonlinear multiple-input multiple-output (MIMO) uncertain system, and has the elevation, pitch, and travel angles. The proposed robust controller is a hierarchical controller including an attitude controller and a position controller. The position controller generates the desired reference of the pitch angle based on the tracking error of the travel angle, while the attitude controller achieves the reference tracking of the pitch and elevation angles. It is proven that the tracking errors of the three angles can converge into the given neighborhoods ultimately. Experimental results on the laboratory helicopter demonstrate the effectiveness of the proposed hierarchical control strategy.