Study On The NOE Flight Control And Terrain Following Of Attack Helicopter

The flight control system of attack helicopter and the influence of disturbance during NOE flight are studied in this dissertation. And the use of H∞ robust control and dynamicinversion schemes in flight control system are discussed. In this paper involved several aspects about the inner and outer loops design for helicopter flight control system, maneuver flight simulation for helicopter, terrain following simulation and 3D animation flight simulation system designed with OpenGL.Because model of helicopter is a highly coupled unstable nonlinear system, a group of six free-degree linear motion equations in combination with micro disturbance and couple are established firstly, and analyzed the infection of the disturbance to the helicopter and then mathematical Models of wind shear and turbulence are represented. This work supplied the basis for the design of the flight control system.Secondly, the modes of RCAH and ACAH are designed with H∞ robust control and dynamic inversion schemes. The controller is designed at two time scales. And the simulation shows the uncoupling of four loops is achieved with H∞ robust control anddynamic inversion schemes.Thirdly, the paper used linear quadratic state actuator scheme to design the velocity controlling loop. In order to test the anti-disturbance capability of the flight control system, the models of wind shear and turbulence are introduced to the flight control system. The result of simulation shows the flight control system has excellent anti-disturbance capability. Then several typical maneuvers are picked up to simulate, and the result shows that the control system can satisfy the design specification of ADS33D criteria .The design of terrain following system is another important part of the dissertation. The terrain following system is designed by adaptive angle method. But there are some problems in the system so the improved adaptive angle method is given. Then above the typical terrain and under the disturbance the terrain following system is simulated. The result shows the flight control system can withstand the disturbance and track the optimal trajectory.Finally, the thesis developed 3D animation flight simulation platform for helicopter using OpenGL in Visual C++. And the 3D terrain and helicopter model are constructed. The simulation of two typical maneuver (S maneuver flight and BopUp-BopDown) and terrain following shows that the fight control system of attack helicopter is improved by the realistic optical impact.