Drag Free Control Design for a space-based Gravitational Wave Observatory = Drag Free Control Design for a space-based Gravitational Wave Observatory

The thesis work presented here deals with the control strategy adopted to maintain a space system in a desidered work condition during the observation phase of its mission. The system consists of three spacecrafts displaced in a triangular formation. In each of the them there are two floating test masses and it is equipped with sensors and actuators. The whole system is supposed to work as an interferometer. Its mission is to observe Gravitational Waves in a certain frequency range (0.1mHz-100mHz). The goal of the thesis is to design the MIMO controllers for the actuators, i.e. micro-thrusters and the electro-static suspensions, to maintain the two test masses at the center of the spacecraft by minimizing the effect of disturbance. The micro-thrusters control the spacecraft attitude, while the electro-static suspensions control the attitude and the translation of the test masses. All the controllers have been designed through H-infinity approach, based on the loop shaping technique. During the design phase the controllers have been validated through Simulink simulations aimed to check the performance of the MIMO controllers in a expected mission scenario. The design phase has been followed by a validation one. In fact, the system is affect by parameters uncertainties and variations. Thus a Monte Carlo campaign has been done to validate the controllers and test their robustness in non-nominal condition.