Aim of this paper is to provide
a survey of the theory of
impulsive control of Lagrangian systems.
It is assumed here that an external controller
can determine the evolution of the
system by directly prescribing the values of some of the coordinates.
We begin by motivating the theory with a couple of elementary examples.
Then we discuss the analytical form taken by the equations of motion,
and their impulsive character. The following sections review
various results found in the literature concerning the continuity
of the control-to-trajectory map,
the existence of optimal controls, and the asymptotic
controllability to a reference state.
In the last section we indicate a further application of the theory,
to the control of deformable bodies immersed in a fluid.