Robust Control Techniques for High-Power Electric Geostationary Satellites with Rotating Solar Arrays

Optimal robust sun-pointing control for the Eutelsat 172B, a large geostationary electrical-propelled satellite, is addressed in this thesis. For spacecraft which propulsion module is based exclusively on high-power electric engines, it is crucial to guarantee the optimal power production during the whole mission. Moreover, for telecommunication satellites is fundamental to maintain the desired pointing to fulfill mission and operational requirements, despite external perturbations that could affect their orientation. To optimize the power generation, guaranteeing proper solar-array sun-tracking, while tracking the desired Earth-pointing orientation of the satellite and its payloads, a first-order Sliding Mode Controller and a Tube-based Robust Model Predictive Control strategy have been implemented, combined with a controller for arrays sun tracking. Both attitude controllers proved to be able to reject the environmental disturbance torques and the modelling uncertainties due to the inertia modification caused by solar panels re-orientation. Moreover, we demonstrate how the proper control of solar array orientation can improve the solar power production. This aspect could allow, during the design phase, to reduce the solar array area and the satellite weight mass, thus further reducing launch and mission costs. The first part of this thesis work is devoted to the development of the Eutelsat 172B simulator, focusing on the environmental disturbances, the multibody dynamics model of the satellite and the electrical power production system. The second part is devoted to the design of the attitude and solar arrays drive controllers.