Strain transducers for active control

Abstract

This thesis presents the results of a theoretical and experimental study of active vibration control using velocity feedback with piezoceramic actuator(s) and closely located velocity sensor(s). The first part of the thesis presents modeling and design studies for a square piezoceramic actuator used to implement a single channel velocity feedback control with a velocity sensor at its center. A fully coupled mobility model of the panel with a square piezoceramic patch actuator is introduced and experimentally validated in order to predict the sensor-actuator open loop response over much wider frequency range than is commonly used, so that the stability of the feedback control loop can be properly assessed using the Nyquist criterion. These simulations suggest that increasing the width and reducing the thickness of the square actuator improves the control performance of a single channel velocity feedback control loop in the case considered. The second part of this thesis investigates a new configuration of the velocity feedback control system, which is composed of a piezoceramic actuator shaped as isosceles triangle with a velocity sensor at its tip. A fully coupled mobility model has been developed, which predicts the response of the sensor-actuator pair more accurately than the conventional modeling method. The implementation of a 16 channel decentralized control system using triangular actuator has been experimentally demonstrated. Significant levels of attenuation, up to 20 dB, are achieved at the first few resonant peaks in term of both structural vibration and sound radiation. Closed loop measurements have highlighted that the control performance are significantly improved by increasing the base length and/or the height of the triangle actuators, with the limitation that the increase of the height reduces the usable frequency range of the control system.

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