In this paper, the use of state feedback control to enhance the sensitivity of modal frequencies to local damage is introduced. The method is intended for smart structures, which embody self-actuation and self-sensing capabilities. A simple example introduces the principle of sensitivity enhancing control for a single degree-of-freedom structure. Then, the method is applied to a finite element model of a cantilevered beam to demonstrate the magnitude of sensitivity enhancement achievable for modest, local damage. Methods of implementing state estimate feedback using point measurements of strain along the beam are described, and initial experiments demonstrating sensitivity enhancement for the cantilevered beam are reported. Results show that enhancement in sensitivity of modal frequencies of vibration to damage can be achieved using a single piezoceramic actuator and multiple piezoelectric strain sensors along the beam. The same sensor-actuator configuration can be used for vibration suppression or other control tasks, providing `dual use' smart structure sensors and actuators.
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