Study On Optimal Terminal Guidance Technology With Multiple Constraints For Hypersonic Vehicle

This paper takes the background of the development of hypersonic vehicle,aiming at the problem of optimal terminal guidance with multiple constraints for hypersonic vehicle,on the basis of summarizing the development status and trend of hypersonic vehicle and multi-constraint optimal terminal guidance technology,an optimal terminal guidance law with multiple constraints(OGLMC)is derived,further consideration of the engineering application of optimal guidance law,in-depth study of key issues such as guidance information acquisition of OGLMC,influence of radome error on the performance of OGLMC,guidance matching of OGLMC and seeker disturbance rejection rate,the main research contents of this paper are as follows:Firstly,the development status and trend of hypersonic vehicle and multi-constrained optimal terminal guidance technology are summarized.The terminal guidance motion model of hypersonic vehicle is established,in order to analyze the optimal terminal guidance law with multiple constraints and its engineering application,the typical theories in the design of guidance system are introduced,which are accompanied by the adjoint method and the non dimensional method,and the basic principle of the two methods and the application criterion in the analysis of the guidance system are presented.Secondly,aiming at the problem of multi-constraint terminal guidance for hypersonic vehicle,such as maximum flight acceleration,seeker’s angle of view,terminal position,terminal impact angle and terminal small acceleration command instructions,establishing the guidance model in the two-dimensional plane,power function of time-to-go is introduced into the dynamic integral term of performance function,by using Schwartz inequality method the optimal solution of optimal terminal guidance law which is based on the state feedback form is derived,under the assumption of small angle,the optimal solution is converted into the form of the guidance law for the convenience of engineering realization.Using the adjoint method and the non dimensional method,the guidance law is proved to be the optimal guidance law with terminal position and terminal angle constraint,and when the guidance order is greater than zero,it has the characteristic of zero terminalacceleration command.Further consideration of flight acceleration and seeker’s angle of view,the analytical expression for seeker’s angle of view and flight acceleration is derived,then,the design strategy of the guidance parameters is presented,which satisfies the flight acceleration and seeker’s angle of view,finally,the adaptability and effectiveness of the optimal terminal guidance law with multiple constraints and the guidance parameter design strategy under nonlinear large angle guidance are verified by simulation.Thirdly,considering of the problem of guidance information acquisition for OGLMC in engineering,the research on the extraction methods and principles of line of sight and angular rate of platform seeker,strapdown seeker and phased array radar seeker is carried out,then analysis of the seeker zero error of platform seeker accuracy of output signal and its influence on the guidance of miss distance,considering of the strapdown decoupling requirements of phased array radar seeker for missile body motion,the extraction scheme of line of sight rate which based the feedforward compensation of missile angular rate is studied,then proposing an error angle compensation strategy with beam steering error.Under OGLMC,the adaptability of the traditional estimation algorithm of time-to-go is studied,then,based on curvature trajectory compensation theory,by approximate calculation of the trajectory curvature of the closed loop flight trajectory of the optimal guidance law,an improved estimation algorithm of time-to-go for the optimal guidance law is derived,and the accuracy and effectiveness of the algorithm are verified by simulation.Fourthly,in light of the influence of radome error on the performance of OGLMC for radar homing missile,based on the radome error model of radar seeker,a multi-constrained optimal terminal guidance system is established which contains the parasitic loop of radome error,employing the model,the effect of radome error on performance parameters and guidance stability of optimal guidance system is analyzed,and the variation law of the system stability region with radome error and the time constant of angle of attack is given.Considering the parasitic loop of radome error and introducing the typical noise of radar seeker,the adjoint method and dimensionless method is employed to analyze the non dimensional guidance miss distance of PNG and OGLMC,the conclusions can provide beneficial theoretical basis to the overall design under the radome and guidance scheme for radar homing hypersonic vehicle.Finally,in order to analyze guidance matching of OGLMC and seeker disturbance rejection rate,based on the definition of seeker disturbance rejection rate,the model of disturbance rejection rate of platform seeker and strapdown seeker is established respectively,and the main reasons for the problem are analyzed.According to the multi-constraint guidance system model considering the parasitic loop of seeker disturbance rejection rate,the non dimensional method and the Routh stability criterion is employed to study the guidance stability of OGLMC with platform seeker and strapdown seeker,the results show that the stability of system is affected by the positive and negative feedback characteristics of the parasitic loop,the amplitude of the seeker disturbance rejection rate,the non dimensional time constant of angle of attack and the order of the guidance law.Introducing the disturbance of terminal impact angle,target constant maneuver and target random maneuver,we established the adjoint system of guidance miss distance which contains the parasitic loop of seeker disturbance rejection rate,through the results of the simulation,it is obvious that OGLMC can sustain a disturbance rejection rate of about 2%for platform seeker,as well as 4% for strapdown seeker.In the practical applications,it is essential to control the level of disturbance rejection rate of seeker strictly and reduce the effect of parasitical loop on the stability of guidance system so that a superior guidance performance of the multi-constraint guidance law can be ensured.The research results of this paper can provide important theoretical support and engineering application basis for the development of optimal terminal guidance technology for hypersonic vehicle.