Eigenstructure Assignment In The Flight Control System Design

Modern high performance aircraft need more advanced fight control systems, while it is more difficult to design these systems by using the classical control theory only. To obtain the better flight qualities, many modern control methods are applied in the design of aircraft flight control systems. Flight control systems are designed by eigenstructure assignment method for traditional aircraft, aircraft with thrust vector and aircraft with direct force control in this paper.The main works of the paper are given as follows:How to successfully apply the eigenstructure assignment method in flight control systems is studied. The design step of eigenstructure assignment method is given. Some aircraft modes, such as attitude hold, altitude hold, automatic landing, turn coordination, heading hold and lateral bias modification are designed and simulated. Flight performance reaches the first-class of flying quality. Finally the software of flight control law is programmed. It has good interface and is convenient to use.An improved eigenstructure assignment method is applied to design the flight control system for aircraft with thrust vector. The method adopts output feedback to assign the eigenvalue and eigenvector of the closed loop system, and at the same time it introduces a feedforward compensator and an integrator. The control system designed by the improved method has good following performance and robustness. The control system realizes that the rotations around three axes have the same dynamic response.For aircraft with active control, eigenstructure assignment method is first used to design direct lift mode;then a nonlinear control method is used to design yaw pointing mode. Flight control system designed by this nonlinear control method can achieve decoupling control, and has better adaptability to inaccurateness of model and the change of system parameters.