MEMS Gyroscope Self-Calibration via Capacitive Compensation
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Solution Overview
Problem
Microelectromechanical gyroscopes face systematic errors due to imperfections in capacitive coupling and temperature variations, leading to unstable offsets that limit their accuracy and noise performance, especially in applications requiring low noise levels.
Innovation Solution
A microelectromechanical gyroscope with capacitive compensation modules and calibration components that detect and mitigate systematic errors through transduction signals, allowing for self-calibration and compensation of offsets and quadrature errors, enabling continuous calibration throughout the device's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If factory calibration using auxiliary capacitances is performed, then initial offset compensation is achieved, but calibration stability deteriorates due to temperature variations and aging
Solution Approach 1:
The gyroscope performs self-calibration during normal operation by continuously monitoring its own output signals. The calibration components detect systematic errors from the transduction signals and automatically adjust the capacitive compensation modules without external intervention, enabling the device to maintain its own calibration stability throughout service life
Solution Approach 2:
The calibration components continuously monitor the transduction signals and provide feedback about systematic errors to the capacitive compensation modules. This closed-loop feedback mechanism allows real-time detection and correction of offset drifts caused by temperature variations and aging, maintaining measurement precision over time
2Measurement precision
If demodulation and filtering are used to process offset, then frequency translation is achieved, but dynamics is saturated and signal fraction is compressed
Solution Approach 1:
The capacitive compensation modules perform preliminary compensation of systematic errors before the signals undergo demodulation and filtering. By correcting offsets in advance, the dynamics of subsequent processing stages are not saturated by large offset values, preserving more dynamic range for the actual measurement signal
3Measurement precision
If capacitive coupling configuration is optimized for driving and sensing, then measurement capability is improved, but systematic errors increase due to process spread imperfections
Solution Approach 1:
The capacitive compensation modules act as intermediary elements that compensate for imperfections in the capacitive coupling configuration. These modules introduce adjustable capacitances that counterbalance the systematic errors arising from manufacturing variations in the driving and sensing electrode arrangements
Solution Approach 2:
The calibration components dynamically adjust the capacitance parameters of the compensation modules to optimize performance. By changing the capacitance values in response to detected systematic errors, the system compensates for manufacturing imperfections and maintains measurement precision
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 effectively reduces systematic errors and maintains calibration stability despite temperature variations and aging, ensuring improved accuracy and reduced noise levels, allowing for reliable operation in applications with stringent noise requirements.
Implementation Method 1
The movable mass and the stator are capacitively coupled through a plurality of respective comb-fingered electrodes facing one another so as to form capacitors. The movement of the movable mass with respect to the stator modifies the capacitance of the capacitors
Implementation Method 2
In the event of rotation of the microstructure with respect to a pre-set gyroscopic axis with an angular velocity, it is subject to a Coriolis force proportional to the angular velocity itself
Implementation Method 3
by supplying appropriate biasing voltages, it is possible to apply an electrostatic force to the movable mass to set it in motion
Data Source
AI summary
A microelectromechanical gyroscope having a supporting structure; a mass capacitively coupled to the supporting structure and movable with a first degree of freedom and a second degree of freedom, in response to rotations of the supporting structure about an axis; driving components, for keeping the mass in oscillation according to the first degree of freedom; a read interface for detecting transduction signals indicating the capacitive coupling between the mass and the supporting structure; and capacitive compensation modules for modifying the capacitive coupling between the mass and the supporting structure. Calibration components detect systematic errors from the transduction signals and modify the capacitive compensation modules as a function of the transduction signals so as to attenuate the systematic errors.