Pattern Centroid Estimation as Basis for Accurate Optical Pressure Measurement

A.O. Niedermayer, T. Voglhuber-Brunnmaier, S.J. Rupitsch, and B.G. Zagar (Austria)


pattern centroid estimation, optical pressure measurement, spatial frequency estimation, image processing


The local measurement of highly dynamical pressure pro cesses in a hydraulic fluid systems is a profound measur ing problem due to the small number of noninvasive sensor principles that are suitable. In most cases the pressure ex cursion is typically followed by formidable flow velocities which lead to quick degradation of any immersed sensor. In this paper we present a technique where a gas bubble that can easily be generated at the location of interest within the fluid acts as a sensory element whose pressure dependent diameter is read out optically. We elaborate on the digi tal image processing of diffraction pattern generated by the optical read–out process. We show that accurate pattern centroid estimation is indispensable for precise measure ments of localized fluid pressure values.

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