Angular Rate Sensor Anti-Phase Coupling for Linear Acceleration Rejection
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Solution Overview
Problem
Existing angular rate sensors, such as gyroscopes, are susceptible to linear acceleration noise due to in-phase parasitic modes, which are difficult to suppress effectively, leading to errors and noise in rate signals, especially in dual-mass vibratory systems where conventional coupling methods fail to resist bending and buckling under linear acceleration forces.
Innovation Solution
The design incorporates two generally planar proof masses with a planar supporting frame, flexible beams for suspension, and anti-phase couplers with link springs and supporting beams that constrain the masses for precise anti-phase movement, decoupling drive and sense modes to minimize in-phase resonance and enhance noise rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional coupling method is used in dual-mass approach, then the sensor structure is simple, but the in-phase linear vibration mode resonant frequency is below the anti-phase drive-mode, allowing centroid movement in response to linear acceleration
Solution Approach 1:
The patent changes the mechanical coupling parameters by using a rigid connection between the two masses instead of flexible coupling elements. This rigid connection forces the masses to move in anti-phase during drive mode while completely preventing in-phase movement, thereby eliminating the parasitic resonant mode that causes linear acceleration susceptibility.
Solution Approach 2:
The patent extracts and eliminates the problematic in-phase mode by using a coupling method that only allows anti-phase movement. The rigid connection between masses removes the degree of freedom that would otherwise allow in-phase vibration, effectively taking out the harmful parasitic mode from the system.
2Object-affected harmful factors
If arcuate coupling member is used to resist in-phase movement, then in-phase mode is suppressed, but the coupling member bends and buckles under linear acceleration forces in the drive direction
Solution Approach 1:
The patent replaces the arcuate coupling member (which relies on elastic deformation to resist in-phase movement) with a rigid mechanical connection. This substitution eliminates the bending and buckling problem because the rigid connection does not rely on elastic deformation to maintain its coupling function, thereby improving reliability under linear acceleration forces.
3Object-affected harmful factors
If multiple levers, pivots, and flexures are used in coupling structure, then in-phase translational movement is suppressed, but the structure becomes complex and each proof mass must split into two parts moving in arcuate motion
Solution Approach 1:
The patent segments the coupling function into a simple rigid connection between the two masses, eliminating the need for multiple levers, pivots, and flexures. This segmentation approach achieves in-phase suppression through the fundamental anti-phase movement constraint of the rigid connection, rather than through complex mechanical linkages.
4Object-affected harmful factors
If differential processing of electrical signals is used to reject linear acceleration in sense direction, then sense direction linear acceleration rejection is achieved, but un-cancelled residual signal becomes error and noise in rate signal due to process imperfections
Solution Approach 1:
The patent extracts and eliminates the source of linear acceleration error by using a rigid coupling that prevents in-phase movement. This mechanical constraint removes the parasitic mode that would otherwise generate false sense signals, eliminating the need for differential processing and its associated residual errors from process imperfections.
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 configuration significantly suppresses in-phase mode resonance, reducing linear acceleration-induced errors and noise, while maintaining efficient anti-phase mode operation, thereby improving the accuracy and reliability of angular rate sensing.
Implementation Method 1
Each anti-phase coupler includes a pair of link springs and a supporting beam... The link springs extend from respective masses to the supporting beam... Under this arrangement, a link spring can be approximated as a rigid bar with rotation hinges attached to its both ends
Implementation Method 2
means for suspending the masses from the supporting frame for movement along a sense axis
Implementation Method 3
means for constraining the masses for anti-phase sense-mode oscillation along the sense axis in response to Coriolis forces produced by rotation of the masses about the input axis
Data Source
AI summary
An angular rate sensor having two generally planar proof masses disposed along a drive axis in the plane of the masses, a sense axis perpendicular to the drive axis, and an input axis perpendicular to the plane of the masses. The masses are suspended from a pair of driving frames, which are mounted and constrained for anti-phase linear movement along the drive axis in drive-mode. Detectors responsive to the anti-phase movement of the masses in directions parallel to the sense axis in response to Coriolis forces produced by rotation of the masses about the input axis for monitoring rate of rotation about the input axis.