Research On Coordinated Robust Control Of Hypersonic Flight Vehicle

Since hypersonic flight vehicle has flexible maneuverability,larger flight envelope,rapid flight speed and strong coupling characteristics,the efficient control technics are significant to improve its safety and reliability.However,the coordinated control study of such aircraft is quite difficult because the strong coupling between the varibales and the aerodynamic parameters always interact with each other,and it will further increase the control design difficulty for the hypersonic flight vehicle.In addition,it is necessary to fully consider the parameter uncertainties and the external disturbances in the flight control design phase of the hypersonic flight vehicle.This dissertation analyses the model of hypersonic flight vehicle and its robust coordinated control is investigated by considering strong coupling,external disturbance and parameter uncertainty.The main contributions are given as follows:Firstly,according to the public experimental data and former achievements,the twelve-state kinematic and six-degree-of-freedom equations of the hypersonic flight vehicle are modeled.The coupling dynamics of the hypersonic flight vehicle and its polar are analysed based on the model,and the analysis mainly involve the following aspects: the attitude angles,the attitude anglular rates and the attitude angles altogether,the control surfaces,and the longitudinal system.Secondly,a coordinated controller is designed for hypersonic vehicle attitude system.Based on the statistical sampling coupling analysis method,a series of coupling analysis are accomplished to acquire the effect between the group of state variables and input variables.In order to improve the applicability of the coupling matrices in control,then the coupling entropies is defined.By using coupling analysis method,two types of coordinated factors are designed and their values can be obtained from the corresponding coupling entropies,then the coordinated factors and control law are combined to obtain coordinated torque.By using allocation matrix,the coordinated torque is allocated to the control deflection commands.Whereafter,a nonlinear robust coordinated control is designed for the attitude dynamics of a generic hypersonic flight vehicle.The proposed design scheme takes into account the coupling among the aerodynamic control surfaces and the whole attitude angles coupling.Then,a series of novel coordinated factors are designed.The uncertain nonlinear functions in the flight vehicle model are approximated through projection mapping.Subsequently,this paper focuses on the relashionship between coupling and system stability,a novel coupling characterization index is introduced to indicate whether a coupling benefits the system or not.The control scheme is designed to eliminate the detrimental couplings while sustaining the beneficial couplings.The spotlight of this paper is the explicit utilization of the system couplings in the controller design which leads to a better dynamic performance.The robustness of the proposed controller is enhanced by using a disturbance observer.Finally,a nonlinear robust coordinated controller is designed for the longitudinal channel of hypersonic flight vehicle.To study the coupling relationships,a coupling analysis is accomplished for the group of state variables and input variables by using statistical sampling method and couping diagrams.Then,a new hierarchical coordinated control strategy,which combines a coupling compensator and a robust controller,is proposed to reject the coupling effects of speed subsystem and altitude subsystem respectively.In the attitude subsystem of longitudinal system,a coordinated transformation technique is introduced to solve the directive derivative coupling.Considering the system uncertainty and the unknown external disturbance,an adaptive controller based on projection mapping is designed.