We study a random process on R n moving in straight lines and changing
randomly its velocity at random exponential times. We focus more precisely on
the Kolmogorov equation in the hyperbolic scale (t, x, v) → t ϵ, x
ϵ, v, with ϵ \textgreater{} 0, before proceeding to a
Hopf-Cole transform, which gives a kinetic equation on a potential. We show
convergence as ϵ→ 0 of the potential towards the viscosity
solution of a Hamilton-Jacobi equation ∂t\"I + H (∇x\"I) = 0
where the hamiltonian may lack C 1 regularity, which is quite unseen in this
type of studies. R{\'e}sum{\'e