Piezoelectric Accelerometer Parasitic Capacitance Compensation
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Solution Overview
Problem
Existing acceleration-measuring devices with piezoelectric vibrating accelerometers fail to accurately compensate for parasitic electrical characteristics such as stray capacitance and resistance, which vary between devices and over time, affecting measurement accuracy.
Innovation Solution
A method and device that excite the piezoelectric vibrating cell with signals at both the resonant frequency and correction frequencies different from the resonant frequency, allowing for the extraction and subtraction of correction signals representative of parasitic electrical characteristics, thereby isolating and compensating for these effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parasitic electrical characteristics are compensated using a fixed one-size-fits-all approach, then the compensation method is simple, but the measurement precision deteriorates due to variations between devices and over time
Solution Approach 1:
The patent applies parameter changes by measuring parasitic electrical characteristics at multiple different frequencies (including frequencies other than the resonant frequency) and using these varied measurements to calculate compensation values. This allows the compensation to adapt to actual device variations and temporal changes, significantly improving measurement precision while maintaining reasonable system complexity through systematic multi-frequency measurement approaches.
2Measurement precision
If excitation signals are applied only at resonant frequency, then the device operation is simple, but the ability to extract and compensate parasitic characteristics deteriorates
Solution Approach 1:
The patent segments the excitation signal application into multiple distinct frequency components. By applying excitation signals at the resonant frequency and at additional frequencies (including frequencies where capacitive effects are minimized), the system can separately measure and distinguish different parasitic characteristics. This segmented approach enables accurate extraction and compensation of parasitic effects while keeping the operational procedure systematic and manageable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise compensation of parasitic electrical characteristics, improving the accuracy of acceleration measurements by isolating the effects of capacitance and resistance from the main signal, resulting in reduced residual errors.
Implementation Method 1
a piezoelectric vibrating cell having an excitation electrode receiving an excitation control signal at a resonant frequency of the vibrating cell and a detection electrode
Implementation Method 2
exciting the vibration cell by means of an excitation signal at a resonant frequency of the vibrating cell
Data Source
AI summary
The invention provides a method of measuring an acceleration by means of a vibrating accelerometer including a piezoelectric vibrating cell, the method having the steps: of exciting the vibration cell by means of an excitation signal at a resonant frequency of the vibrating cell; of calculating an acceleration value from a detection signal that results from the excitation signal; of exciting the vibrating cell with a correction excitation signal at a correction frequency that is different from the resonant frequency; of extracting a correction signal from the detection signal, the correction being representative of an electrical characteristic that is to be corrected; and of combining the correction signal with the detection signal so as to reduce the electrical characteristic that is to be corrected.