A current procedure that takes into account the Dirichlet boundary condition
with non-smooth data is to change it into a
Robin type condition by introducing a penalization term; a major effect of this
procedure is an easy implementation of the boundary condition.
In this work, we deal with an optimal control problem where
the control variable is the Dirichlet data.
We describe the Robin penalization,
and we bound the gap between the penalized and the non-penalized boundary controls
for the small penalization parameter.
Some numerical results are reported on to highlight
the reliability of such an approach.