Research On Flight Control Law Model Design And Application Method For Conceptual Aircraft Design

Modern air-to-air combat environment requires that the fighter airplanes have increasing performance demands of sorts, which is more difficultly satisfied by the traditional aircraft design method. According to studying the concept of Control-Configured-Vehicle (CCV) and the theory of Multidisciplinary Design Optimization (MDO), a thought that the integration of flight control disciplinary in an aircraft conceptual design process is given. Thus, an approach of Flight Control Law (FCL) model design and application for aircraft conceptual design is researched.Firstly, the principles of Flight Dynamics and Control (FD&C) are discussed. An aerodynamic database, which satisfies the analysis requirements of integration of FD&C in the aircraft conceptual design process, is built. In the practical engineering, because the FCL is not designed or not completely designed in the phase of the aircraft conceptual design, especially in the phase of aircraft preliminary design, Simplified FCL (SFCL) model based on conventional control theory and Generic FCL (GFCL) model based on Nonlinear Dynamic Inversion (NDI) method are presented.Secondly, SFCL is designed using the Linear Quadratic Tracker (LQT) for longitudinal system and eigenstructure assignment method for lateral system. Gain-scheduled is designed by a two-layer BP neural network technique. The designed SFCL is evaluated by equivalent system matching and Simulink numerical simulation. GFCL is designed by NDI method. The states and airframe model of aircraft are separated into groups respectively by time-scale separation method. Then control laws are designed respectively in different groups. The designed GFCL is evaluated using Simulink numerical simulation. Then, a scheme that coordinating and designing aircraft conceptual design project using the designed SFCL and GFCL, is proposed.Finally, a fighter airplane example is given and the results of evaluation demonstrate that the approach is reasonable, available and feasible. This approach can also be a reference of a practical flight control system design.