Flying qualities evaluation based nonlinear flight control law design method for aircraft

Abstract

This paper is focused on the parameter tuning problem for the design of nonlinear flight controllers. Taking into account the preferences and requirements of the pilot, a novel flying qualities evaluation framework and a tuning method are proposed for the design of nonlinear flight controllers. Considering that the existing flying qualities criteria are not applicable to evaluating the closed-loop aircraft system, a novel evaluation framework consisting of three modules namely ideal reference model, controller and aircraft model, is proposed. Based on this evaluation framework, an overall evaluation model is established, the flying qualities based rating scores for this model will reflect the level of the controller performance. Subsequently, a schematic evaluation method, consisting of three sub-procedures namely linearization, low-order equivalent fitting and flying qualities criteria based rating, is proposed for the controller design. To validate the evaluation framework and the method, a nonlinear F/A-18 aircraft model and the incremental backstepping control law are chosen to build a demonstration example. Theoretical analysis and the simulation results reveal that the proposed evaluation framework and schematic method are effective for the design of nonlinear flight control laws.