OPTIMAL COUPLED SPACECRAFT RENDEZVOUS AND DOCKING USING MULTI-OBJECTIVE OPTIMIZATION

Spacecraft rendezvous and docking are two processes in which a chaser pursues and meets a leader spacecraft in order to perform several mission based tasks. Although in some preliminary design analysis, these two operations may be pursued independently there could be circumstances in which the spacecraft trajectory and attitudes are coupled and interdependent. The present study is based on the presumption that the often independent translational and rotational motions of the spacecraft are coupled as a result of thrust misalignment. So the thrusters not only contribute to the rendezvous translational motion, but also affect the docking reorientation maneuver through their disturbing effects.. In this regard, the coupled spacecraft rendezvous and docking (RvD) maneuver is treated as a multi-objective optimization problem. Multi-objective ant colony optimization ( ACO(R)) and Genetic algorithm (GA) as new variants of multi objective metaheuristics that have proven to be successful in handling non convex and multi minima problems are utilized to determine the required pareto front. Three design points are selected such that a wide range of mission based operations are covered and the results are compared. It is shown that, despite the presence of the disturbing effects due to the thruster misalignment, the required control commands are reasonable. For a comparative analysis, two different schemes are also utilized to obtain the closed loop control form for the RvD problem under study and their results are compared.