Optimization And Simulation Of Reentry Trajectory For Hypersonic Vehicle

During the last ten to twenty years,with the rapid development of hypersonic flight technology,the requirements for hypersonic vehicles are getting higher and higher.However,the changes in the atmosphere environment that aircraft flying are violent and complicated,and they have strict restrictions on the flight process.All these factors have put forward higher requirements for the performance indexes of the aircraft.The optimization of the flight trajectory can not only promote the design and determination of the flight mission,but also coordinate the unified work among the aircraft mechanisms,and improve the overall performance of the aircraft.Therefore,as a necessary condition for the whole design of aircraft,the optimization of flight trajectory of aircraft is very important and must be solved.First of all,the coordinate system is defined in order to build the model that hypersonic vehicle flying in the near space.Based on the dynamics and kinematics equations of the aircraft with the atmospheric model of the environment given by reference documentation,a simplified model of three degree of freedom reentry vehicle is established.Secondly,in order to combine with the optimization algorithm,this paper presents a multi constrained nonlinear mathematical model for the trajectory optimization of reentry vehicle,including the optimization variables and constraints.In addition,the influence of the number of parameters and the constraint handling method in the mathematical model have been analyzed.The fitness function is designed according to the given objective function in order to search the optimal solution of flight trajectory efficiently.At the same time,the genetic algorithm is studied,aiming at some problems existing in the standard genetic algorithm that the encoding process is more complex and the speed of convergence of the algorithm will be decreased,the particle swarm algorithm was used to improve the searching capability of the algorithm.Then the reentry trajectory has been simulated by using the improved genetic algorithm,selecting the right number of parameters and specific constraint handling method,combined with the motion model of reentry trajectory of the hypersonic vehicle aircraft.It shows that the optimization ability of the improved genetic algorithm is improved and the optimal results meet the requirements of task was obtained.Finally,in order to combine the research results with the engineering applications,so that the researchers can have a more intuitive understanding of the simulation process.In this paper,VC++ is used as the programming language,and the Open GL function library is synthesized.The simulation results of MATLAB are combined with the simulation results of the trajectory,and the visual simulation experiment is done.The results achieved the desired effect which can not only show the change of the space position of the aircraft,but also show the change of the attitude angle.