Accelerometer Pole-Piece Asymmetry to Reduce Proof-Mass Displacement
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Solution Overview
Problem
Accelerometers experience reduced accuracy due to vibrations causing imbalance in magnetic flux and Lorentz forces, leading to displacement of the proof mass from the null position.
Innovation Solution
The accelerometer system redistributes magnetic flux by altering the distribution and symmetry of magnetic flux loops using features such as chamfers or fillets on pole pieces to counterbalance asymmetries, maintaining the proof mass at the null position and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard symmetric pole pieces are used, then the accelerometer system is simple to manufacture, but vibrations cause imbalance in magnetic flux leading to reduced measurement accuracy
Solution Approach 1:
The patent applies asymmetry by providing pole pieces with different geometries - specifically, first pole pieces with a first geometry and second pole pieces with a second geometry that is different from the first. This asymmetric design creates different magnetic flux paths for vibrations in opposite directions, causing the flux imbalances to cancel each other out and improve measurement accuracy
Solution Approach 2:
The patent implements local quality by modifying specific regions of the pole pieces with different geometries rather than changing the entire structure. The asymmetric geometries are applied locally to the pole pieces to create targeted magnetic flux distribution changes that compensate for vibration-induced imbalances
2Measurement precision
If asymmetric pole piece geometries are used, then measurement accuracy is improved by counterbalancing magnetic flux imbalance, but manufacturing complexity increases
Solution Approach 1:
The asymmetric pole piece geometries are designed to be complementary - when one pole piece has a certain geometric feature, the opposing pole piece has a corresponding different feature. This allows the asymmetric structures to be manufactured using standard processes while maintaining the beneficial flux-balancing effect
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 enhances the accuracy of acceleration measurements by minimizing net changes in magnetic flux and Lorentz forces, ensuring precise determination of acceleration values.
Implementation Method 1
a first magnet configured to generate a first magnetic flux... a first coil disposed around the first pole piece, wherein the first magnetic flux flows from the first excitation ring to the first pole piece across the first coil... cause a first current to flow through the first coil to apply a first Lorentz force to the proof mass
Data Source
AI summary
An accelerometer system including: a first magnetic assembly including a first pole piece; a second magnetic assembly including a second pole piece, wherein a physical shape of the second pole piece is different than a physical shape of the first pole piece; and a proof mass assembly including: a proof mass between the first magnetic assembly and the second magnetic assembly. A first magnetic flux flows from the first magnetic assembly to the first pole piece, wherein a magnitude of the first magnetic flux across the first coil is based on the physical shape of the first pole piece; A second magnetic flux flows from the second magnetic assembly to the second pole piece, and wherein a magnitude of the second magnetic flux is based on the physical shape of the second pole piece.