Displacement Control of Elastic Structures: Integral Control with a Robustness Property

The issue of design of feedback controllers for elastic structures is addressed, where the objective is accurate and robust displacement control of the structure. Motivation for the work arises from study of control of multi-story buildings as part of the pseudo-dynamic-test method. If the force actuators have "fast" dynamics suitable control may be achieved by feedback of structural displacements and velocities, usilng a PID type controller logic. If the force actuators have "slow" dynamics it is suggested that structural accelerations also be fed back to the controller. Locations of the assigned closed loop poles are specified which guarantee robustness to variations in the actuator time constant and to uncertainties in the structural stiffness. Simplifying assumptions are made so that results are obtained using elementary arguments.