This paper deals with the problem of designing a
robust fault detection methodology for a class of input-output,
uncertain dynamical distributed parameter systems, namely
mechanical elastodynamic systems, which are representative of
a whole class of problems related to on-line health monitoring
of mechanical and civil engineering structures. The proposed
approach does not require full state measurements and is
robust to measuring, modeling and numerical errors, thanks
to a time varying detection threshold. In order to avoid the
problems associated with classical discretization techniques for
distributed parameter systems, which can lead to numerical
errors difficult to bound a priori, and thus higher thresholds,
a suitable structure-preserving algebraic approach, called Cell
Method, will be employed. This method consists in writing the
equations of a distributed parameter system directly in discrete
form, avoiding the usual discretization process and leading to
a symplectic, that is energy preserving, numerical scheme
