Research On Trajectory Optimization And Guidance For Hypersonic Gliding Vehicle

Hypersonic gliding vehicle has a large flight space,a wide range of flight speed,and a fast global strike capability,which is currently the research focus of all countries.There are many constraints in the flight process of glider,and the flight environment is complex.The optimal guidance method based on trajectory optimization can generate guidance instructions to meet the mission requirements according to the real-time flight state and constraints of the aircraft,overcome the impact of deviation and disturbance in the flight process,and has the adaptability and robustness that the traditional guidance method does not have.Therefore,this paper will focus on the research of trajectory optimization and optimal guidance methods for hypersonic gliding vehicle.In this paper,the development history of hypersonic vehicle at home and abroad is investigated in detail,the theoretical system of trajectory optimization and reentry guidance is combed,the applicability of various trajectory optimization methods and the advantages of reentry guidance methods are analyzed,providing reference for the research work.Aiming at the problem of trajectory optimization studied in this paper,firstly,the definition and transformation relationship of coordinate system are introduced,then the dimensionless mathematical model of aircraft is established in the half speed coordinate system,and the control variables are designed in turn,and the constraint conditions are determined.Combined with the actual flight background,two kinds of performance indexes are analyzed respectively to complete the establishment of trajectory optimization model.In order to solve the problem of reentry trajectory optimization,Gauss pseudospectral method is used to optimize the trajectory.Firstly,the principle of Gauss pseudospectral method is introduced.The continuous time optimal c ontrol problem is discretized on a series of LG points,and Lagrange interpolation polynomials are used to fit the state quantity,control quantity and constraint conditions.The transformed nonlinear programming problem is obtained,and the sequential quadratic programming algorithm is used to solve it.In order to achieve the optimal guidance of reentry process,it is necessary to verify the optimality of trajectory optimization solution.In this paper,based on the minimum principle and the pseudospectral co-state mapping theorem,a method to verify the optimality of the optimal solution is deduced.In this paper,two kinds of performance indexes,the shortest time and the smallest change of track angle,are compared and analyzed.The results show that the minimum change of track angle can effectively reduce the jumping of track.Then,different weights are applied to the two kinds of performance indexes,and the influence of the weights on the trajectory optimization is analyzed.Finally,the performance index weights that can make the trajectory more stable and realize the fast strike task are optimized.The optimization of trajectory optimization solution is also verified by numerical method.In this paper,the feedback strategy based on Carathéodory-? is given,and the optimal guidance scheme based on pseudospectral feedback method is designed,so that the trajectory satisfying the optimal performance index can be obtained by on-line optimization according to the real-time state during the flight.This paper introduces the on-line execution strategy of the commonly used pseudo spectral feedback method,and designs the corresponding guidance strategy based on the actual flight characteristics of the hypersonic gliding vehicle studied in this paper,and proves the boundedness of guidance error through theoretical derivation.After that,the simulation is carried out under the condition of no deviation and limit deviation,and the robustness and optimality of the optimal guidance method is preliminarily verified.Then,through the Monte Carlo shooting experiment,it is verified that the optimal guidance method based on pseudo spectral feedback method can effectively overcome the interference of multiple deviations and disturbance factors in the reentry process of hypersonic gliding vehicle,and the guidance The accuracy meets the requirements of terminal energy window.