Office National D'etudes Et De Recherches Aerospatiales (onera)

Claude Galaud

Alain E Bruere

A capacitive dimensional measurement chain with linear output is essentia comprised of a capacitive sensor formed by a central detection electrode and a guard electrode surrounding the detection electrode that are respectively powered by two a.c. bias voltage sources. The chain also comprises a reference capacitor and a measuring circuit for measuring the distance between the detection electrode and a conductive part placed facing the detection electrode. The bias voltage sources are variable level sources and are level-controlled by a distance measurement signal issued by the measuring circuit. The measuring circuit comprises a level amplifier and a demodulator for amplifying and demodulating an incoming error signal representative of a difference between a load of a sensor capacitance that is defined between the detection electrode and the part separated by the distance to be measured, and a load of the reference capacitor. The distance measurement signal supplied by the measuring circuit linearly represents the distance to be measured.

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Paris, France

Claude Galaud