Robust control of vertical flight and rotor speed for mini-helicopter

A robust nonlinear control method for the vertical motion and rotor speed of a helicopter is presented in this paper. A nonlinear model of vertical motion and rotor speed is considered including the aerodynamics of the main rotor based on blade element method. A nominal MIMO controller for the nominal plant is designed to decouple the dynamics between the vertical motion and the rotor speed and to achieve desired performances. Simultaneously a robust compensator is added to eliminate the effect of the external disturbance and the uncertainties of the model and the parameters, which ensures that the robust performance of the actual system. It is proven that for a given constant initial state, the tracking error of the actual system could decline into any specified boundary in a limited time. The results of flight experiment show the effectiveness of the method for the disturbances and uncertainties as well as the precision of tracking reference signal.