Feedback control of the second order evolution equations with damping

Feedback control is developed for a class of distributed systems described by the second order evolution equations with slight damping. In order to increase the degree of stability of the system, a dynamic compensator is designed on the basis of a finite-dimensional model of the system, and a feedback control system is constructed by using sensor outputs. It is shown that the degree of stability of the whole system including the compensator is improved by "modal control" based on a finite-dimensional modal model.