  Recent dynamical models, based on the seminal work of V. Hill, allow to
predict the muscular response to functional electrostimulation (FES), in the
isometric and non-isometric cases. The physical controls are modeled as Dirac
pulses and lead to a sampled-data control system, sampling corresponding to
times of the stimulation, where the output is the muscular force response. Such
a dynamics is suitable to compute optimized controls aiming to produce a
constant force or force strengthening, but is complex for real time
applications. The objective of this article is to construct a finite
dimensional approximation of this response to provide fast optimizing schemes,
in particular for the design of a smart electrostimulator for
muscularreinforcement or rehabilitation. It is an on-going industrial project
based on force-fatigue models, validated by experiments.Moreover it opens the
road to application of optimal control to track a reference trajectory in the
joint angular variable to produce movement in the non-isometric models.
