Study on Target Tracking Control for a Free-Floating Space Robot

Kurzfassung

We can consider the satellite servicing as a tool able to enable the creation of a new architectures needed to conquer the next frontiers in space. In this regard, the German Space Agency, DLR, is working for years on projects for the realization of on-orbit servicing missions as for example one to capture a tumbling client satellite with a servicing spacecraft and to perform the de-orbiting of the coupled system within a predefined orbit corridor at the end of the mission. The contribution to such project in this work has been to implement an Impedance control for the Free Floating manipulator, supposed mounted on the Chaser spacecraft, able to track the Target satellite during the Rendezvous phase. The report is divided in three main chapters, the first one is a introductory chapter dedicated to servicing missions, in particular to the importance that they cover in various sectors not only in the scientific, proven by the various missions completed during the story. Particular attention is given to the experience of DLR in this area and on the description of DEOS project. In the second chapter presents all the theoretical foundations at the base of ground testing of Rendezvous phase of a typical servicing mission. Emphasis is placed on the simulation of the Target satellite motion and Free Floating base for the Chaser spacecraft as well as the strategy control used for the system. In the last chapter are presented the results of numerical simulation, emphasizing how the choice of the control parameters influences the behaviour of the system and finally is introduced and analysed a type of control able to make robust the system control against the uncertainty on the manipulator dynamic model.