Spacecraft modelling and control for on-orbit servicing missions

On-Orbit Servicing is meant to revolutionize the aerospace industry, focusing on the sustainability of space activities. Such missions rely on robotic manipulators allowing to perform life-extending operations on existing assets or to mitigate the problems related to space debris. In recent years, the idea of a Space Tug, a multi-purpose vehicle capable of operating in complete autonomy, was developed in forecast of the importance that on-orbit servicing will play as a consequence of the increment of Earth orbiters. The aim of this work is the developement of a simplified Functional Engineering Simulator and the design of a Guidance, Navigation and Control system for a Space Tug mission concerning the active removal of a piece of space debris. The project is carried out by making use of Matlab and Simulink to model and simulate the system and to implement the required algorithms. A combined control approach is adopted, which considers the rototranslation of the satellite and the angular positions of the manipulator joints as different degrees of freedom of the same plant. This approach grants the cooperation of the actuation systems for obtain the desired motion for each part of the vehicle. The results show that it is theorically possible to provide a compensation balancing the dynamic coupling between the base and the robotic arm.