Nonlinear H_∞ flight control

This paper presents the application of nonlinear H_∞ state feedback theory to flight control. We divide the flight control into attitude control and velocity control which are different to the conventional longitudinal and lateral control. The new control framework which is based on nonlinear H_∞ state feedback theory design the nonlinear H_∞ controller using the 6 D aircraft governing equations directly. Linear models are not necessary. This new flight control methodology has the separation property which we can design the attitude controller and the velocity controller independently. Moreover, it can be shown that controller can be designed before parameter identification of the aircraft. On the other hand, the solutions of the nonlinear H_∞ controllers are sets. Hence we can find a controller from the solution sets to satisfy the performance specifications. The time responses, control energies and robustness by different controllers and different output weights will be discussed in this paper.