Research On Fractional Order PID Controller And Adrc For Hypersonic Vehicle

As the development of hypersonic speed technology, the flight control system of reentry vehicle is made more and more high demand. In the reentry process of hypersonic vehicle, its dynamic model appears to a big uncertainty and strong coupling nonlinear systems, and control ability of the aircraft flying within the earth's atmosphere is controlled only by aerodynamic con is limited. Furthermore, the external interference to the projectile also cannot be ignored. All these factors make the design of reentry control system of hypersonic vehicle becoming one of the challenges in the hypersonic technology field. This article mainly aims at the study of high precision and strong stable flight control of hypersonic vehicle.First, The paper choose aerospace vehicle (ASV) as the research object, and then establish and perfect the six-degree of freedom dynamics and kinematics equations at the condition of the hypersonic reentry. The analysis of the coupling character shows that this model can reflect hypersonic reentry vehicle is a kind of strong coupling, rapid time-varying nonlinear system, and also satisfy the demands of theoretical study and simulation validation of the flight control system of hypersonic vehicle.Secondly, for the hypersonic vehicle attitude control system of a large uncertainties and complex nonlinear characteristics of, also considering the external disturbance influence to the aircraft during the reentry process. Combining with the technology of auto-disturbance-rejection control, this paper designs an auto-disturbances-rejection gesture controller. We design the extended and smooth state observer by constructing Qin function, The high frequency vibration phenomenon in the process of its traditional application is also weakened. We make the outside interference, uncertain model, coupling channel and pneumatic parameter perturbation influence as a "total interference" to get the value of the real-time interference. Through the improvement of extended and smooth state observer, it realize the real-time dynamic feedback compensation and the linearization of the system. By using nonlinear feedback control law to curb compensation residual, the control performance is improved. Moreover, we show the controller's stability using Lyapunov function, and provide basic theory to the selection of controller parameter. Through the simulation results, show the controller is of validity and robustness.Auto-disturbances-rejection controller using nonlinear feedback control law is difficult to get parameters , by using nonlinear PID control law can seek virtues and operate values, also obtain better control quality , thus it is more suitable for single input and single output system. Therefore, this paper puts forward Oustaloup digital algorithm to realize the optimal fractional calculus and establish fractional PID controller model, and design auto-disturbances-rejection fractional order PID controller basing on the extended state observer.Then, using auto-disturbances-rejection fractional PID control method, we study trajectory tracking matters in the reentry gliding process of the aircraft at the hypersonic flight conditions. Basing on the flight constraints, the aircraft resistance acceleration - velocity profile reentry corridor is made. By selecting the appropriate resistance acceleration signal as aircraft reference trajectory, we design the reentry guidance trajectory tracking control system of the aircraft. Through the analysis of the performance measure of the robust energy indicates that fractional order PID has stronger robustness. Simulation results show the validity of the vehicle guidance control system.To solve the fractional order system modeling will lead to obvious increase of the model order. So, in this paper, we put forward a changing order times state space modeling method, make the fractional systems extend to the state space area, realize the minimum order state space conversion basing on the superposition principle of fractional order operator. For whose order times are less than 1 variable order state space achieving fractional order systems, A changing order fractional order system's stability criterion theorem is put forward. Fractional order system's changing order state space modeling and stability theory is beneficial for the extended application of integer order state space theory in the fractional order systems.Finally, the fractional calculus will be introduced to the guidance law design of the hypersonic vehicle press section and puts forward a fractional guidance law of the reentry press section basing on the fractional order system's changing order state space model,select parameters of fractional guidance law with optimal control. Through the analysis results, compared with the traditional proportional guidance law, fractional guidance law raised the guidance accuracy, is not sensitive to guide coefficient change. At the same time, because of the introduction of fractional calculus, it has strong robustness and a good correction ability to the deviation parameters of the reentry points.