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A study about how to design a control law that not only keeps following a reference attitude but also maintains attitude decoupling due to the vehicle manoeuvres has been performed. A control law was designed for a satellite launcher vehicle using eigenstructure assignment and optimal control method in order that the vehicle tracks a reference attitude and also to decouple the yaw response from roll and pitch manoeuvres and to decouple the pitch response from roll and yaw manoeuvres. It has been noticed that in order to achieve this objective it is necessary to use a linear coupled model to design the control law instead of the usual linear uncoupled model used to design the tracking control law. The design was based on a complete linear coupled model obtained from the complete vehicle non-linear model by linearisation at each trajectory point. A comparison of the system stability working with both control laws has also been performed. After all, the design was assessed with the vehicle time varying non-linear model showing a good performance and robustness. The used design method is explained and a case study for the Brazilian satellite launcher VLS is reported. By the end of the work some suggestions about how to implement this control law have also been studied.

A study about an on-off satellite launcher control law design for attitude tracking and decoupling was carried out. The study considered a linear decoupled and a linear coupled model of the vehicle to obtain the controller gains. A comparison between the performance given by each design was performed The stability analysis of both designs was also carried out using the describing function technique and the circle criterion. Finally the robustness of the design based on the coupled model was assessed with respect to uncertainties on the control forces and on the inertial parameters. It was assumed the vehicle flying a ballistic phase outside the atmosphere

This work describes the strategy of a hybrid simulation program to be used in order to assess the performance of a satellite launcher control system. The hybrid simulation starts with two simulation programs, one that simulates the on board computer with control laws and the other that simulates the rest of the system. After validation of these two programs the hardware interfaces are then included. After a new validation, the real actuators are included in the system, and finally the real sensors are included. So in the final phase only the vehicle dynamics is simulated digitally, and as this is the most real condition possible before the real flight, it represents the best condition to assess the flight control system performance and to detect possible problems not clear at the design phase. The work describes mainly the method used in order to obtain a very reliable hybrid simulation program for a satellite launcher control system.