Full-course Reentry Trajectory Design For Horizontal Landing Hypersonic Vehicle

The horizontal landing hypersonic vehicle has been widely concerned and studied at home and abroad due to its high reusability and cost-effectiveness.In this thesis,the whole reentry trajectory design problem for horizontal landing hypersonic vehicle is studied.According to the flight profile,the whole flight is divided into initial reentry,Terminal Area Energy Management(TAEM)and Approach and Landing(A&L).The trajectory design algorithms and simulation cases analysis are given respectively.Firstly,the common used coordinate system and its conversion relationship are introduced.The earth model and the vehicle aerodynamic model are given.The kinematics and dynamics equations of the horizontal landing hypersonic vehicle are derived and combined with the motion characteristics of each flight segment,which provides theoretical basis for the trajectory planning algorithm.The initial reentry trajectory is designed based on the traditional predictor-corrector algorithm.Non-dimensional motion model is deduced and established.For a given angle of attack(AOA)profile,the terminal range-to-go is predicted by using the longitudinal reduced order motion model,and the linear bank angle magnitude profile is corrected by satisfying final height,velocity and range-to-go constraints.The sign of bank angle is determined based on the heading angle error corridor strategy.The real-time prediction and correction are carried out to obtain the initial reentry trajectory.To overcome the shortcomings of traditional algorithm,such as undesirable phugoid oscillation,the quasi-equilibrium glide condition(QEGC)is used to adjust the longitudinal lift by introducing altitude rate feedback compensation.To manage the heating rate,load factor and dynamic pressure constraints,the reference altitude rate form is derived,and the bank angle is adjusted by feedback compensation lift component to track the reference altitude rate,so as to enhance the path constraints.As for the TAEM phase,the basic principle of energy management is given.The cubic polynomial is used to obtain the reference dynamic pressure vs height profile vertically.The AOA control is obtained by tracking the derivative of the reference dynamic pressure to altitude.The bank angle control is obtained by tracking lateral segmented design ground-track,and the ground geometry of the overhead and direct heading alignment mode is derived.The terminal state is deduced by a reduced order motion model with altitude as an independent variable.The selection of heading alignment mode,the iterative correction of the minimum radius and the position of the heading adjustment cone(HAC)is used to satisfy the terminal constraints and achieve the matching of the range and the dissipative energy relationship.Then the segmented profile method is used for A&L trajectory planning.The vertical continuous smooth trajectory segments are refined designed,and the corresponding geometry relationship is established.Appropriate parameters are selected to meet the constraints of load and descent rate.The AOA control is obtained by solving vertical differential-algebraic equations with dynamic pressure as state variables.At the same time,the bank angle control is determined by the lateral motion.The trajectory is propagated to get the terminal state.Then the trajectory design problem is reduced to a two-point boundary value problem,and the down-track distance flown is adjusted by iterating a single geometric parameter to satisfy the touchdown dynamic pressure constraint.Finally,the simulation cases result and analysis of the whole reentry flight for the horizontal landing vehicle are given to verify the feasibility and validity of the trajectory design algorithms proposed in this thesis.