Control systems on semi-simple Lie groups and their homogeneous spaces

In the present paper, we consider the class of control systems which are induced by the action of a semi-simple Lie group on a manifold, and we give a sufficient condition which insures that such a system can be steered from any initial state to any final state by an admissible control. The class of systems considered contains, in particular, essentially all the bilinear systems. Our condition is semi-algebraic but unlike the celebrated Kalman criterion for linear systems, it is not necessary. In fact, it appears that there is no semi-algebraic necessary and sufficient condition in the bilinear case and that our criterion is in some sense optimal. This will be discussed in a future paper.