The Research On The Longitudinal Direct Lift Control Decoupling Method And Real-time Simulation System

Direct lift control (DLC) is one of the most important parts of the active control technique (ACT). DLC is a technique which has the aircraft fly vertically to change its trajectories by proper movements of flight control surfaces without changing the attitude of the aircraft. Nowadays DLC technique is widely used in the design of the third generation combat aircraft and airbus. This paper chooses the AFTI/F-16 for the research object and gives a deep research on the technique of DLC.The paper is organized as follows.Common aircraft under the moment control inevitably has long time lag from the implement of the flight control surfaces to the changing of the flight trajectories when the aircraft changes its attitude. In order to solve the problem, DLC technique was provided. Since DLC directly gives effect on the forces acting on aircraft, it can eliminate the coupling between the force and moment. So the coupling between flight attitudes and flight trajectories is eliminated and lag time is reduced. Decoupling is the key of the DLC. The methods dynamic asymptotic decoupling, dynamic inversion and eigenstructure assignment are researched and improved to realize the technique of DLC.Virtual reality (VR) is the use of advanced technologies for interactive design, including computers and various multimedia peripherals, to produce a simulated environment that users perceive as comparable to real world objects and events. Because of its value on the visualization of the simulation, the author applies it to the simulation and realizes the combination of techniques between flight control design and virtual reality. System of real-time display technology of visual simulation focus on DLC is designed. Three-dimension modeling method and technique of modeling rendering is introduced.Longitudinal DLC contains three modes: vertical transition, pitch appointing, direct lift. Focus on three mode talked above, the paper uses dynamic asymptotic decoupling, dynamic inversion and eigenstructure assignment three methods to design controller of aircraft AFTI/F-16, and realizes the technique of DLC. After the simulation of flight control system with the use of soft Matlab, author programmed it with the C language and embeds it into the real-time display system. The visual simulation of DLC is achieved.