Discrete Multiobjective Optimization Applied to the Spacecraft Actuators Command Problem and Tested in a Hardware-in-the-Loop Rendezvous Simulator

Kurzfassung

The challenge of commanding efficiently and autonomously spacecraft actuators has motivated the investigation of new optimization techniques in order to extend the spacecraft’s life and to insure the fulfillment of all mission requirements. The control problem of spacecraft using actuators with conflicting characteristics has been explored in this thesis. Thus a novel autonomous command strategy based on a discrete multiobjective optimization approach has been proposed herein. This innovative methodology, called Actuator Multiobjective Command Method (AMCM), determines the best way to operate a given group of actuators according to predefined specifications and online acquired inputs. This function generates a set of feasible solutions and selects, based on a decision making method, the best compromise solution optimizing a group of objective functions simultaneously and completely online. It is assumed the final approach rendezvous scenario, due to its complexity, for testing the models. In addition, the hardware-in-the-loop rendezvous and docking simulator facility of the German Aerospace Center, called European Proximity Operations Simulator (EPOS), has been used to test and validate the proposed method. This facility uses two industrial robots to physically simulate the complete translational and rotational motion of two docking satellites. Furthermore, all elements of the guidance, navigation, and control loop have been developed and implemented accurately in a simulation framework and tested, at EPOS, under real-time environment conditions using rendezvous sensor-hardware. The developed software brings forward effectiveness and robustness proving to be able to generate reliable results in both non-real-time and real-time simulations.