Study on Optimization Methodology for Launch Trajectories of GTO Launchers

Abstract

In this paper methodology for GTO launch trajectory optimization design is proposed, which is based on trajectory decomposition optimization �√ bilevel programming method and Genetic Algorithms. Aiming at the poor convergence problems caused by the couple of system variables and optimal control variables, the bilevel programming model was developed, in which the master's problem only dealt with the system variables, and the junior problem only dealt with the trajectory optimal control variables. The all -up trajectory optimization design problem was divided into two branching trajectory optimizations design problems, which can guarantee the optimal solutions. The optimal control problems were conversed into nonlinear programming problems by multiple parameterization methods. The problems of high sensitivity to the initial guess and local convergence were very critical when applying the classical algorithms t o solving the corresponding nonlinear programming problems. Aiming at this problem, a pipeline hybrid approach was proposed. The hybrid approach adopted population search -based GA with global convergence as a method to produce a good guess to solutions, a nd then applied Powell Algorithm to completing the optimization process. As an example, maximal payload optimization design of a two -stage GTO launcher was completed, several problems including influence of parameters of launch trajectory were discussed, a nd several constructive conclusions were gained. Applications show that the optimization methodology for GTO launch trajectory design has predominant holistic performance index, and has great engineering appli cation value.