Helicopter H_∞ control design with robust flying quality

The purpose of this paper is to design helicopter H_∞ flight control system to improve its stability, maneuverability, and agility. Firstly, the linear mathematical model of a helicopter is established from the nonlinear six degree-of-freedom dynamic equations. Then, linear H _∞ control theory is applied to the linearized model to design the H_∞ controller, which, in turn, is integrated in the nonlinear model of a helicopter to simulate nonlinear dynamic response, and to evaluate flying quality. Two helicopter flying quality indices, quickness index and phase delay margin, are adopted to test the robustness of H _∞ controller, and the results show that while the forward velocity of helicopter changes, the H_∞ controller can maintain the specifications in level-1 standard.