Lie algebra rank condition for bilinear control systems on ${\mathbb{R}}^2$

We will study the controllability problem of a bilinear control system on ${\mathbb{R}}^2:$ the main result is the characterization of the Lie algebra rank condition for the system. On the other hand, using elementary techniques, we recover conditions for the controllability of the induced angular system on the projective space. Finally, we will give controllability criteria for the system.