Angular Velocity Sensor Beam Isolation for Coriolis Detection
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Solution Overview
Problem
Existing angular velocity sensors using coriolis force face errors due to direct coupling of the detecting member with the mass portion, leading to undesirable changes in the area of facing electrodes and significant excitation amplitude affecting detection results.
Innovation Solution
The detecting member is positioned on the beam, which is partitioned into portions with different spring constants, allowing indirect detection of mass portion displacement by detecting beam vibrations, thereby isolating the influence of excitation amplitude and enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the detecting member is directly coupled onto the mass portion, then the detection structure is simplified, but the excitation amplitude significantly affects the detection result causing serious error
Solution Approach 1:
The patent introduces a beam as an intermediary element between the mass portion and the detecting member. The beam transmits the vibrational motion from the mass portion to the detecting member while isolating the detecting member from the direct influence of excitation forces. This mediator structure allows the detecting member to sense only the coriolis-induced vibrations in the detecting direction, filtering out the harmful excitation amplitude effects.
2Power
If the mass portion is excited in the excitation direction, then the coriolis force is generated for detection, but the area of facing electrodes changes causing detection error
Solution Approach 1:
The patent applies local quality by creating different structural characteristics in different portions of the beam. The first portion has a spring constant optimized for excitation direction flexibility, while the second portion has a spring constant optimized for detecting direction stability. This localized differentiation allows the excitation-induced area change to be confined to the first portion, while the second portion maintains stable electrode facing area for accurate detection.
Solution Approach 2:
The beam is segmented into multiple portions with different spring constants. This segmentation allows each portion to perform its specific function: the first portion accommodates excitation motion, while the second portion maintains stable detection geometry. The segmentation isolates the harmful area changes to specific regions, protecting the detection function.
3Device complexity
If the beam has uniform spring constant, then the structure is simplified, but the excitation amplitude cannot be isolated from detection
Solution Approach 1:
The patent implements local quality by assigning different spring constant characteristics to different portions of the beam. The first portion has a spring constant that allows flexible excitation motion, while the second portion has a spring constant that provides stability in the detecting direction. This localized property differentiation enables the beam to simultaneously accommodate excitation and maintain detection accuracy without requiring complex additional structures.
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 enables stable detection of angular velocity by minimizing the impact of excitation amplitude on the detecting member and effectively measuring vibrations caused by coriolis force, resulting in accurate angular velocity measurement.
Implementation Method 1
When an alternating current voltage is applied to the segmented electrode, electrostatic attraction is generated between the movable electrode and the fixed electrode, thereby enables the mass portion to vibrate in the excitation direction.
Implementation Method 2
the distance between the plane electrodes on the mass portion side and the substrate side which constructs the capacitor, i.e. the detecting member, is thereby changed; consequently, this change in the distance causes the electrostatic capacitance of the capacitor to modulate.
Implementation Method 3
in a case where angular velocity is applied to the mass portion while it is being excited in the excitation direction, a coriolis force occurs in a direction (i.e. the detecting direction) that is orthogonal to both the excitation direction of the mass portion and an axial direction of rotation of the angular velocity
Data Source
AI summary
Beams 70a, 70b, 70c and, 70d of an angular velocity sensor 100 is provided with a folded type beam 73 that has a spring constant which is smaller along the excitation direction (x-axis direction) than along a detecting direction (y-axis direction), and a straight type beam 75 that has a spring constant which is smaller along the detecting direction (y-axis direction) than along the excitation direction (x-axis direction). The folded type beam 73 is arranged closer to the mass portion 40 than the straight type beam 75. The detecting member 60 is disposed on a farther beam portion of the beam 70b, wherein the farther beam portion is arranged farther away from the mass portion 40 than the folded type beam 73.