非线性最优控制理论及MATLAB实现,【JL091】最优控制理论研究及其MATLAB实现.rar

最优控制理论及MATLAB实现,【JL091】最优控制理论研究及其MATLAB实现.rar"/>

非线性最优控制理论及MATLAB实现,【JL091】最优控制理论研究及其MATLAB实现.rar

【JL091】最优控制理论研究及其MATLAB实现.rar

英 文 翻 译 系 别 自动化系 专 业 自动化 班 级 191002 学生姓名 粘风姣 学 号 103623 指导教师 韩治国 、李雪霞 Optimal Spacecraft Rendezvous Using Genetic Algorithms Young Ha Kim and David B. Spencer Pennsylvania State University, University Park, Pennsylvania 16802 Introduction The total solution to the optimal spacecraft rendezvous problem contains many local optimal with discontinuous parts between them that can inhibit convergence to the global optimal solution.Conventional calculus-based optimization s are not effective in these kinds of problems because the optima they seek are the best in the neighborhood of the current point and are dependent on the existence of derivatives. These conventional s require an accurate initial guess to identify promising trajectories;unfortunately,it is not always easy to determine the initial guess. The goal of this paper is to introduce the use of genetic algorithms for optimal space rendezvous.At the time a rendezvous sequence is initiated,the two space vehicles may be far apart in significantly different orbits. The rendezvous is accomplished when both space vehicles attain the same position vector and velocity vector at the same time.In this paper, only coplanar transfers are analyzed because there are well-known analytical solutions Hohmann and bi-elliptical transferswith which to compare results. The initial and final orbits define the boundary conditions such that the initial orbit is the chase vehicles orbit and the final orbit is the target vehicles orbit. Optimal Rendezvous Using a Genetic Algorithm The goal of the optimal rendezvous is to obtain a thrust time history,which includes the thrust direction, magnitude, and the burn time, such that the boundary conditions are satisfied to an acceptable level, and to provide these solutions in a reasonable time. The transfer of a spacecraft from one point in space to another is a fundamental problem in a story dynamics known as Lamberts problem.Rendezvous is Lamberts problem where the space vehicle matches both the position and velocity of the target.For the general orbit transfers, three variables per trajectory segment need to be coded into the genetic algorithm.In the case of a rendezvous problem, thevariables are 1v, , and . These variables are shown in Fig. 1.A space vehicle moving with initial velocity v.t / leaves the initial orbit r.0 after thrusting.The velocity of the space vehicle becomes v0, which is the summation vector of the initial velocity vector v.0 and the velocity change vector1v. The space vehicle arrives in the final orbit if the vehicle has the suitable thrust profile. The genetic algorithm finds the optimal thrust profile,similar to what was done in Refs. 1 and 2 for orbit transfers.Where this work differs is that a second saneuver is made causing a rendezvous to occur. Genetic Algorithm The genetic algorithm GA is a stochastic global search that mimics some aspects of natural biological evolutio