Resonant Sensor Electrostatic Proof Mass Control
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Solution Overview
Problem
Existing resonant sensors lack sufficient sensitivity and stability for precise acceleration measurements, particularly in applications like specific gravity measurement where high-resolution and low-frequency accelerations are required.
Innovation Solution
A resonant sensor design featuring a substrate with a proof mass suspended for relative movement, coupled resonant elements, and an electrode assembly with drive and sense circuitry to resonate and calibrate, allowing for the application of calibration signals and DC biasing to enhance sensitivity and stability, and incorporating damping electrodes for quick motion retardation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If resonant sensors are used for acceleration measurement, then frequency output stability is improved, but measurement precision for low-frequency accelerations deteriorates
Solution Approach 1:
The patent applies dynamic tuning by making the proof mass adjustable through electrostatic actuation. The proof mass can be dynamically repositioned along the sensitive axis using electrode assemblies that apply electrostatic forces, allowing the resonant sensor to adapt its resonant frequency and measurement characteristics in real-time. This dynamic adjustment resolves the contradiction by enabling the sensor to optimize its operation for different frequency ranges and measurement conditions.
Solution Approach 2:
The patent changes physical parameters of the resonant sensor system, specifically the proof mass position and distribution, to adjust the resonant frequency and sensitivity characteristics. By varying the proof mass position through electrostatic actuation, the sensor can shift its operating parameters to achieve both frequency stability and improved low-frequency acceleration measurement precision as needed.
2Measurement precision
If proof mass is made movable for sensitivity, then measurement sensitivity is improved, but stability deteriorates
Solution Approach 1:
The patent implements feedback control through drive and sense circuitry that monitors the resonant frequency and proves mass position, then adjusts the electrostatic actuation signals accordingly. This closed-loop feedback system maintains proof mass stability while preserving measurement sensitivity by continuously correcting for drift and external disturbances, resolving the contradiction between sensitivity and stability.
Solution Approach 2:
The patent replaces purely mechanical proof mass positioning with electrostatic actuation. Instead of mechanical springs or actuators, electrostatic fields are used to position and hold the proof mass, providing more precise control and reduced mechanical friction and wear. This substitution improves both the stability of the proof mass position and the sensitivity of acceleration measurements.
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
The solution provides improved sensitivity and stability for acceleration measurements, enabling precise calibration and reduced temperature sensitivity, while allowing for automatic periodic calibration and active damping, thus enhancing the sensor's effectiveness in measuring low-frequency accelerations.
Implementation Method 1
at least one substrate electrode on the substrate, adjacent to the proof mass; and electric circuitry connected to the substrate electrode configured to apply a voltage to the substrate electrode providing an electrostatic force on the proof mass
Implementation Method 2
drive and sense circuitry connected to the electrode assembly configured to drive the electrode assembly to cause the at least one resonant element to resonate
Implementation Method 3
incorporating damping electrodes for quick motion retardation
Data Source
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AI summary
There is provided a resonant sensor comprising: a substrate; a proof mass suspended from the substrate to allow for relative movement between the proof mass and the substrate along at least one sensitive axis; at least one resonant element coupled to the proof mass; an electrode assembly adjacent to the at least one resonant element; drive and sense circuitry connected to the electrode assembly configured to drive the electrode assembly to cause the at least one resonant element to resonate, wherein a measure of acceleration of the proof mass can be determined from changes in the resonant behaviour of the at least one resonant element; at least one substrate electrode on the substrate, adjacent to the proof mass; and electric circuitry connected to the substrate electrode configured to apply a voltage to the substrate electrode providing an electrostatic force on the proof mass. The substrate electrode may be used to provide a number of different functions.