A nonlinear flight controller design for aircraft

In this paper, a nonlinear flight controller design approach using the method of extended linearization is described and applied to an F-8 aircraft longitudinal model. Performances of both gain-scheduled and the nonlinear controllers are compared using simulation studies. The results indicate that the nonlinear controller is insensitive to the choice of scheduling variable, and returns all the state variables to their respective trim conditions under large initial deviations in angle of attack, while the gain-scheduled controllers fail to do so. In general, the proposed nonlinear control design gives better performance and removes some of the difficulties in the conventional gain-scheduling approach.