Robust Tracking Control For Hypersonic Vehicle

For cost-efficient and time reduced flights in both military and commercial areas, air-breathing engine powered hypersonic vehicle with its significant dual-use value, becomes the main research object of current near space flight technology. Compared with common airplane or flight vehicles, the hypersonic vehicles are designed integrated and the coupling exists between the airframe and the engine. Besides it, there is a larger flight envelope, shorter response time and more complex flight condition for hypersonic vehicles, all of which propose many new research challenges to flight control system design. Based on the generic hypersonic vehicle longitudinal model developed by NASA Langley research center, this paper makes the relevant control research for improving flight performance when the flight vehicle in the cruise section. The main work is as follows:Firstly, it introduces the full-state differential equations of the hypersonic vehicle model and the longitudinal dynamics equations are obtained by decoupling analysis. Meanwhile, the aerodynamic characteristics are discussed after each sub-models analysis and an equilibrium point is sought in the cruise section.Secondly, the feedback linearization techniques are utilized to make the longitudinal model of hypersonic vehicle complete input-output linearization and then the dynamic inverse system is obtained. Based on the dynamic inverse system, the adaptive control idea and the sliding mode control theory are combined so as to design adaptive sliding mode controller to evaluate the uncertain parameters on the line. The simulation results demonstrate that the controller could meet the flight requirements of the hypersonic vehicle on the condition of parameter uncertainties and it has certain robustness, besides, the system equipped with this controller has better transient performance than that of the sliding mode controller.Thirdly, the small disturbance linearization model of the hypersonic vehicle is obtained by calculating the equilibrium point in the flight envelope. And then the LQR controller is designed. Besides, the optimal robust servo system is designed by combining the internal model principle with the optimal control theory. Simulation results demonstrate that in the presence of a wind gust interference and parameter perturbation, the LQR controller could not make the system track the command signal exactly, but the optimal robust servo system could do with certain robustness.Concluding remarks are presented at the end of this dissertation. Some open problems are also pointed out, which deserve further study.