MEMS Gyroscope Bias Suppression via Anti-Phase Proof Mass Alignment
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Solution Overview
Problem
MEMS gyroscopes, such as tuning fork gyroscopes, suffer from bias errors due to vibratory rotation motion, which can lead to navigation solution errors in applications like GPS redundant airplane navigation and gyrocompassing, where non-zero sensor biases cause systems to incorrectly indicate rotation when stationary, resulting in increasing errors over time.
Innovation Solution
The design of a MEMS sensor with proof masses that move in anti-phase along different axes, where the centers of mass are aligned to minimize angular momentum in the sense axis, reducing the occurrence of bias errors by ensuring that vibratory motion does not generate a bias signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If proof masses are driven in anti-phase mode to enable gyroscope measurement, then measurement capability is achieved, but vibratory rotation motion generates bias errors
Solution Approach 1:
The patent applies asymmetry by positioning proof masses at different locations and orientations within the sensor structure. Specifically, the first and second proof masses are positioned such that their centers of mass are not collinear with the drive axis, creating an asymmetric configuration that eliminates the vibratory rotation effect while preserving the Coriolis measurement capability.
Solution Approach 2:
The patent introduces a spatial dimension solution by arranging proof masses in three-dimensional space rather than along a single axis. The first proof mass is positioned at a first location and the second proof mass at a second location, with their centers of mass forming a configuration that extends beyond the drive axis, thereby eliminating the harmful vibratory rotation effect.
2Measurement precision
If proof masses are positioned to eliminate bias errors, then measurement accuracy improves, but device structure becomes more complex
Solution Approach 1:
The patent uses asymmetric positioning of proof masses to eliminate bias errors. By placing the first and second proof masses at specific non-symmetric locations with their centers of mass forming a particular geometric relationship with the drive axis, the design achieves bias suppression without requiring complex active control mechanisms.
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 effectively suppresses imbalance-driven bias errors, maintaining zero angular momentum in the sense axis and preventing navigation solution errors, thereby enhancing the precision of inertial sensors in navigation systems.
Implementation Method 1
the first proof mass and the second proof mass move in anti-phase along a second axis
Implementation Method 2
the motion of the first proof mass and the second proof mass along the second axis is such that the centers of mass of the first proof mass and the second proof mass move collinearly along a same axis
Implementation Method 3
suppresses imbalance-driven bias errors, maintaining zero angular momentum in the sense axis
Implementation Method 4
maintaining zero angular momentum in the sense axis
Data Source
AI summary
Systems and methods for suppressing bias in a non-degenerate vibratory structure are provided. In certain embodiments, a vibratory structure includes a first proof mass; a second proof mass, wherein the first proof mass and the second proof mass are driven into motion along a first axis, wherein the first proof mass and the second proof mass move in anti-phase along a second axis, wherein the motion of the first proof mass and the second proof mass along the second axis is such that the centers of mass of the first proof mass and the second proof mass move collinearly along a same axis.