  This manuscript introduces a passivity-based control methodology for
fully-actuated mechanical systems with symmetric or asymmetric dead-zones. To
this end, we find a smooth approximation of the inverse of the function that
describes such a nonlinearity. Then, we propose an energy and damping injection
approach - based on the PI-PBC technique - that compensates for the dead-zone.
Moreover, we provide an analysis of the performance of the proposed controller
near the equilibrium. We conclude this paper by experimentally validating the
results on a two degrees-of-freedom planar manipulator.
