  Infinite-dimensional control systems with outputs are considered in the
Hamiltonian formulation with generalized coordinates. An explicit scheme for
constructing a dynamic observer for this class of systems is proposed with
arbitrary gain coefficients. Sufficient conditions for the convergence of the
constructed observer are obtained on the basis of the invariance principle.
This result is applied to a flexible beam model attached to a mass-spring
system with lumped and distributed actuators. The estimation error decay is
illustrated with numerical simulations of finite-dimensional approximations of
the observer dynamics.
