  We consider the classical Prandtl-Tomlinson model of a particle moving on a
corrugated potential, pulled by a spring. In the usual situation in which
pulling acts at constant velocity $\dot\gamma$, the model displays an average
friction force $\sigma$ that relates to $\dot\gamma$ (for small $\dot\gamma)$
as $\dot\gamma\sim (\sigma-\sigma_c)^\beta$, where $\sigma_c$ is a critical
friction force. The possible values of $\beta$ are well known in terms of the
analytical properties of the corrugated potential. We study here the situation
in which the pulling has, in addition to the constant velocity term, a
stochastic term of mechanical origin (i.e, the total driving is a function of
$\dot\gamma t$). We analytically show how this term modifies the force-velocity
dependence close to the critical force, and give the value of $\beta$ in terms
of the analytical properties of the corrugation potential and the scaling
properties of the stochastic driving, encoded in the value of its Hurst
exponent.
