제목: Space Trajectory Design: Challenges and Concepts for Optimization​​​

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​​​​​​​​​​​​​​​​​​연사: Prof. Ossama Abdelkhalik  (Iowa State University)​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

장소: 과학관 B103호​​

Abstract:

Trajectory optimization spans a wide range of problems of different characteristics and challenges. For instance, impulsive interplanetary trajectories are characterized by the fact that the number of design variables varies among different solutions. Continuous thrust trajectory optimization, on the other hand, is an optimal control problem that usually require high computational cost and good initial guess for the solution. This presentation presents advances on multiple fronts of the trajectory optimization problem. For impulsive interplanetary trajectories, recent advances in trajectory optimization methods that enable handling problems of variable number of design variables will be presented. One method is the Hidden Genes Genetic Algorithm. In this method, variable-length solutions (chromosomes) are handled by hiding some genes in a long chromosome string. Results of integrating this method with NASA’s EMTG tool will be discussed. Another method is the Structured-Chromosome Genetic Algorithm in which a chromosome is represented by a link list data structure. This structure enables crossover between solutions of different lengths. The talk also presents a new exact solution to Lambert’s problem – a core function in most trajectory optimization problem formulations. For the continuous-thrust trajectory optimization problem, a new approach for optimal control will be presented that enables finding conserved quantities on optimal trajectories. Results will be presented for the case of low-thrust trajectories in a central gravitational field.