Multivariable tuning regulators for infinite-dimensional systems with unbounded control and observation

This paper deals with the problem of multivariable low-gain PI-control of infinite-dimensional stable systems with unbounded control and observation operators. We show that under very mild assumptions a fairly large class of infinite-dimensional systems can be stabilized and regulated by multivariable PI-controllers with sufficiently low gain. The controller design can be accomplished using plant step data, no exact knowledge of the plant is required.