Robust Helicopter Stabilization with Wind Disturbance Elimination

When a helicopter is required to hover with minimum deviations from a desired position without measurements of a persistent wind disturbance, a robustly stabilizing control action is vital. In this paper, the stabilization of the position and translational velocity of a nonlinear helicopter model affected by a wind disturbance is addressed. An estimate of the disturbance is introduced to be adapted using state measurements for control purposes. A nonlinear controller is then designed based on nonlinear adaptive output regulation and robust stabilization of a chain of integrators by a saturated feedback. While in the control synthesis the wind disturbance is assumed to be a sum of a fixed number of sinusoids with unknown amplitudes, frequencies and phases, a practical turbulence model is presented to the helicopter model in the control test. Simulation results show the effectiveness of the control design in the stabilization of helicopter motion and the built-in robustness of the controller in handling parameter and model uncertainties.