Capacitance decoded accelerometer

摘要

A circuit board has an arcuate array of conductor segments each subject to a digital waveform differing in phase for the various segments, and a concentric pickup conductor. A rotary encoder disk has a conductive pattern which sums and couples the waveforms from selected segments, depending on rotary position, to the pickup conductor. A synchronous phase detector generates a phase signal from the summed waveforms and the zero crossing of the phase signal is detected. A counter develops count signals used to generate the digital waveforms. The count signals are input to a latch which is clocked at the zero crossing point to latch the count value which is a digital measure of the encoder angle. Two encoders mounted on orthogonal horizontal axes are used as an accelerometer or attitude sensor. Each disk is eccentrically weighted to seek a position vertically below the axis to serve as an attitude sensor when the unit is stationary. When the unit is subject to horizontal acceleration the disks rotate from the vertical position to render acceleration readings.