Attitude control system design for small satellites using gradient-based methods

The paper presents some aspects for the synthesis of small satellites attitude control system. The nonlinear model of the satellite has six degrees of freedom and it includes rotation angles in order to describe the kinematic of its motion. After linearization of the movement equations, the stability and command matrices are determined and then, a gradient-based method is proposed for the controller synthesis. In order to improve the convergence properties of this gradient method, the adjoint theory was used. Two attitude control cases are analysed in the paper: the first one is the situation when reaction wheels are used for the satellite attitude control. In the second case it is assumed that micro thrusters are used for the attitude control. For this latest case, a configuration including a Trigger Schmidt element is used. The results are developed and used in the framework of the project European Space Moon Orbit - ESMO founded by European Space Agency in which University POLIEHNICA of Bucharest is involved.