Trajectory Optimization And Tracking In Reentry Phase Of Hypersonic Vehicle

Since the first aircraft came out,human beings have always put forward higher and faster requirements for aircraft.With the rapid development of aerospace technology in recent decades,hypersonic vehicle has become one of the hot research directions of modern aerospace.In this paper,the trajectory optimization method of the reentry phase of hypersonic vehicle is studied.Taking the general spacecraft cav-h as the research object,the mathematical model and aerodynamic coefficient model of its reentry process motion are established.On this basis,the trajectory optimization of the vehicle is carried out.The main work of this paper is as follows:Firstly,the motion state and force of the reentry vehicle are analyzed,and the three degree of freedom motion mathematical model of the reentry motion of the hypersonic vehicle is obtained.Then,the constraints that need to be considered in the reentry process are analyzed,and the objective function of trajectory optimization is given.Before trajectory optimization,the basic principle of pseudo spectral method and the optimal control problem based on pseudo spectral method are introduced.In this paper,the problem of trajectory optimization is transformed into a nonlinear,discrete and static planning problem,and it is shown that the obtained planning problem is consistent with the original one.Based on the Guass pseudospectral method,using gpops tool kit,the initial conditions of the reentry process of self-made aircraft are described.The maximum range of the vehicle in the transverse and longitudinal direction is taken as the goal,and the effect of trajectory optimization is illustrated by simulation and analysis of the results.Then,genetic algorithm is used to optimize the trajectory.Firstly,the basic principles of genetic algorithm and particle swarm optimization algorithm are introduced.Then,the process and method to deal with the constraints when genetic algorithm is used to solve the optimal control problem are given.The corresponding fitness function is designed.Then,the simulation of reentry trajectory optimization based on improved genetic algorithm is given The simulation results show that the improved PSO genetic algorithm is effective.At last,the task of reentry corridor design and trajectory planning is carried out.Firstly,according to the constraints faced by the reentry phase of the hypersonic vehicle,the establishment process and mathematical expression of the reentry corridor are given.Then,LQR trajectory tracker is designed to track the longitudinal trajectory of the reentry phase,and then the lateral trajectory of the reentry phase is given Finally,the simulation work is carried out to verify the effectiveness of the controller.