Modification of an On-off Modulation for Thruster Actuators with Differential EvolutionAlgorithm in an Optimal Docking Maneuver

In this paper, an innovative approach is proposed toimprove the performance of a spacecraft dockingmaneuver. The docking maneuver is considered in acircular orbit using on-off thruster actuators. Theminimum energy problem of the spacecraft dockingmaneuver is solved based on optimal control using thedirect multiple shooting method. In this dockingmaneuver, it is assumed that the target spacecraft isuncontrollable and is not tumbling. It is needed to usealgorithms to modulate the continuous outputs of themultiple shooting method for the thrusters. Here, amodification algorithm is proposed based on the timedivided into intervals. A population-based algorithmcalled differential evolution is utilized to do thismodulation. This algorithm selects the best times to turnon each thruster in each interval. Another approach israndomly selecting the turn-on times of the thrusters.The numerical results of the problem show that thedocking maneuver that uses the differential evolutionalgorithm approach increases the docking accuracycompared to the random approach.

Keywords:

Differential Evolution , Docking Maneuver , Optimal Control , Minimum Energy Problem , MultipleShooting