Pole Placement Techniques for Active Vibration Control of Smart Structures: A Feasibility Study

It is well known that there is degradation in the performance of a fixed parameter controller when the system parameters are subjected to a change. Conventional controllers can become even unstable, with these parametric uncertainties. This problem can be avoided by using robust and adaptive control design techniques. However, to obtain robust performance, it is desirable that the closed-loop poles of the perturbed structural system remain at prespecified locations for a range of system parameters. With the aim to obtain robust performance by manipulating the closed loop poles of the perturbed system, feasibility of the pole placement based controller design techniques is checked for active vibration control applications. The controllers based on the adaptive and robust pole placement method are implemented on smart structures. It was observed that the adaptive pole placement controllers are noise tolerant, but require high actuator voltages to maintain stability. However, robust pole placement controllers require comparatively small amplitude of control voltage to maintain stability, but are noise sensitive. It was realized that by using these techniques, robust stability and performance can be obtained for a moderate range of parametric uncertainties. However, the position of closed-loop poles should be judiciously chosen for both the control design strategies to maintain stability.