Development of patch-type smart self-sensing actuator

Abstract

For vibration control applications in smart structure field, a collocated input/output response is generally desired. The original purpose of existing sensoriactuator investigation was to measure the collocated response for system identification. A perfect sensor/actuator collocation usually provides a stable performance in closed-loop feedback controls. In addition, a self-sensing actuator is attractive from the standpoint of minimizing the amount of instrumentation required to control a structure. However, attempts to estimate the exact performance of the sensoriactuator proved to be difficult, and in an attempt to improve the response, the complexity of the compensation technique continually increased. Also an existing sensoriactuator has several problems still such as a hysteretic effect, a phase error, a nonlinear response, a variation of capacitance and so on. In this study, a newly developed sensing-patch and phase tracking method are presented. These are compulsory techniques in order to develop a novel sensoriactuator or a smart-patch. The sensing-patch comprises an extrinsic Fabry-Perot interferometer (EFPI) and a piezoceramic as a direction detector. And a simple and practical phase tracking logic is applied for the real-time tracking of optical phase of an interferometer. An EFPI sensor itself has non-linear behavior due to the interferometric characteristics, and a piezoceramic has a hysteretic behavior. However, the sensing-patch proposed in this study overcomes the problems that can arise in case of individual uses as a sensor. Moreover, it has good strain resolution and wide dynamic sensing range. Finally, a sensing-patch could be extended to the smart-patch which has the capability of simultaneous sensing and actuation. A smart-patch does not only guarantee stabilities in ‘direct-feedback control loops’ like existing sensoriactuator but also has better strain resolution and wider dynamic sensing range than existing sensoriactuator does. Also, ...