  We consider Randall-Sundrum two-brane cosmological model in the low energy
gradient expansion approximation by Kanno and Soda. It is a scalar-tensor
theory with a specific coupling function. We find a first integral of equations
for the A-brane metric and estimate constraints for the dark radiation term. We
perform a complementary analysis of the dynamics of the scalar field (radion)
using phase space methods and examine convergence towards the limit of general
relativity. We find that it is possible to stabilize the radion at a finite
value with suitable negative matter densities on the B-brane.
