Design of a robust controller for the VEGA TVC using the u − synthesis technique

This study has been developed in the European Space Research and Technology Centre (ESTEC) in the TEC-ECN section. The purpose of this study is to design a robust controller for the thrust vector control of the VEGA launcher using the μ−synthesis design. To reach this objective a first study of the equations of motions together with the impact and effect of a classical controller will be done. The studied model will include the rigid body motions together with three bending modes. To get the desired performances it will be necessary to design three different controllers. One for the rigid body behaviour, another for filtering the bending modes and a last one to reduce the angle of attack. In practice the filter for the bending modes is designed by knowing the shape that it should have, without taking the requirements into account. Using a μ−synthesis design for the filter definition the requirements introduced by the weighting functions are satisfied in the better way. The main part of the study will be carried out for the pitch axis. However, at the end of this study a model taking the coupling between pitch and yaw into account will be presented simultaneously with a controller being able to stabilise overall