US 2006/0065052 A1Published application

Extended accuracy variable capacitance bridge accelerometer

AssigneeThe Boeing Company

InventorJoan Wada

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Abstract

A bridge accelerometer system includes four capacitors, wherein two capacitors are formed on each side of a rigid member. The other two capacitors are similarly constructed, except that the rigid member is replaced by a flexured plate. The construction of the plates with respect to the flexured plate is substantially similar to the configuration formed by the rigid member and the other two capacitors, and the fixed capacitors and rigid plate are isolated from the flexured arrangement. The four capacitors are connected to form a bridge generating a bridge voltage signal as a function of a sine wave from a symbol generator. The bridge voltage signal is amplified and converted to digital word in an A/D converter. The digital word is linearized and filtered in a microprocessor, which also includes a precision clock controlling the symbol generator and a conversion clock controlling the A/D converter.

Claims37

Dependent claims

An accelerometer system comprising:

a housing;
a flexure plate section enclosed within said housing and comprising a first fixed plate, a second fixed plate spaced apart from and in parallel relation to said first plate, and a flexure plate disposed between and in substantially parallel relation to said first and second plates,
said flexure plate coupled to said housing along at least an edge, said flexure plate and first plate defining a first distance and a first capacitor and said flexure plate and said second plate defining a second distance and a second capacitor, wherein said first and second distances vary in response to acceleration forces acting upon said flexure plate;
a rigid plate section enclosed within said housing and electrically isolated from said flexure plate section and comprising a third fixed plate, a fourth fixed plate spaced apart from and in parallel relation to said first plate, and a rigid plate disposed between and in substantially parallel relation to said first and second plates,
said rigid plate electrically isolated from said housing, said rigid plate and said third plate defining a third distance and a third capacitor and said rigid plate and said fourth plate defining a fourth distance and a fourth capacitor, wherein a fifth distance is defined between said rigid plate and said flexure plate such that said fifth distance is a function of said acceleration forces,
said first capacitor, said second capacitor, said third capacitor and said fourth capacitor connect to form a bridge adapted to generate a bridge voltage signal;
a symbol generator generating a precision sine wave at a known phase angle for exciting signals of at least one of said first capacitor, said second capacitor, said third capacitor and said fourth capacitor;
and
a precision clock driving said symbol generator.

6 more elements

Dependencies are inferred from the claim text.