Research On Bifurcation Analysis And Control Of The Nonlinear Flight Dynamics

The modern fighter aircrafts with the post stall maneuver ability will own great advantage in the close air battle. The post stall ability has been the basic requirement for the next generation of the fighter aircrafts. In the state of high Angel of Attack (AOA) and post stall maneuver, with the effect of the nonsteady aerodynamic forces, the motion inertia coupling, the nonlinear factors in the Flight Control System (FCS), the flight dynamic system shows the behaviors of nonsteady and nonlinear. The traditional research way, based on linearization and small disturbance, is invalid to study the behaviors of aircraft in the post stall maneuver. How to model the aerodynamic forces in the high AOA, how to analyze the character of the nonlinear model, how to design the flight control system in the high AOA, these are the key technique problems in the cross fields of the flight dynamics, aerodynamics and flight control. These researches have great value in both the theory and the engineering field.Based on the nonsteady experiments in the wind tunnel, the article uses the Artificial Neural Network and Fuzzy Logic to establish the full value and six degree of freedom flight dynamics model. With Bifurcation Analysis and Catastrophe Theories Method (BACTM), the impact of nonsteady and nonlinear aerodynamic forces on the flight dynamics is analyzed. Fusing the Bifurcation Tailor and the Eigenstructure Assignment technique, the close-loop three-target bifurcation tailor is used in the design of the high AOA flight control system. Based on the XML model language, the flexible, general and cross-platform flight dynamic model is established, the flight simulation software is developed. The script simulation and man-in-loop simulation show the effect of the nonsteady aerodynamics and the effect of the flight controller design. Combining all these techniques above, the integrative software frame is established. The modeling, analysis and control software are combined to form as a whole. The software frame provides a powerful technique and software method to do nonlinear flight dynamics research. The work can be applied to the design of the next generation fighter aircrafts.