Time-Domain Inertial Sensor with Sliding Plane Proximity Switch
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Solution Overview
Problem
Current time-domain inertial sensors face challenges in accurately measuring inertial acceleration due to phase noise and jitter, particularly in maintaining stable oscillations and precise position localization of the proof mass.
Innovation Solution
A time-domain inertial sensor design featuring a support structure, a springedly coupled proof mass, and a time-domain proximity switch, which oscillates in the x-direction with minimal gap variation, utilizing electron tunneling or capacitive switches to switch states at predefined reference positions, thereby enhancing phase measurement stability and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the proof mass oscillates with significant gap variation, then the oscillation amplitude is large, but the phase measurement stability deteriorates and phase noise increases
Solution Approach 1:
The patent constrains the proof mass to oscillate in approximately only the x-direction such that the gap between the first surface and the electrode plane does not vary significantly. This dynamic constraint resolves the contradiction by maintaining stable capacitance conditions for phase measurement while preserving oscillation amplitude for sensitivity.
Solution Approach 2:
The patent introduces directional selectivity in the oscillation motion, allowing freedom in the x-direction while constraining motion in the z-direction (gap direction). This local quality differentiation enables the proof mass to achieve sufficient oscillation amplitude without compromising gap stability, thereby resolving the phase measurement stability issue.
2Device complexity
If conventional position measurement methods are used, then the device structure is simple, but the phase noise and jitter increase reducing measurement accuracy
Solution Approach 1:
The patent replaces mechanical position sensing methods with a time-domain proximity switch that detects when the proof mass passes through a reference position. This substitution eliminates mechanical contact and associated noise, achieving high measurement accuracy while maintaining relatively simple device structure.
Solution Approach 2:
The patent uses periodic oscillation of the proof mass combined with a proximity switch that triggers at each passage through the reference position. This periodic action enables precise phase measurement by counting oscillation cycles and measuring time intervals, achieving high accuracy without complex continuous position sensing systems.
3Measurement precision
If the proof mass is constrained to oscillate in only the x-direction with minimal gap variation, then the phase measurement stability improves, but the oscillation amplitude may be reduced
Solution Approach 1:
The patent employs dynamic constraints that allow free oscillation in the x-direction while preventing z-direction motion that would cause gap variation. This dynamic approach maintains large oscillation amplitude in the measurement direction while ensuring gap stability, resolving the contradiction between amplitude and phase measurement stability.
Solution Approach 2:
The patent segments the motion degrees of freedom, treating x-direction oscillation and z-direction gap maintenance as separate independent motions. This segmentation allows the system to optimize each dimension independently - maximizing oscillation amplitude in x while maintaining constant gap in z - thereby resolving the contradiction.
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 design achieves improved stability and accuracy in inertial acceleration measurement by maintaining consistent phase measurement and reducing phase noise and jitter, allowing for precise localization and efficient operation of the phased-locked loop.
Implementation Method 1
utilizing electron tunneling or capacitive switches to switch states at predefined reference positions
Implementation Method 2
utilizing electron tunneling or capacitive switches to switch states at predefined reference positions
Data Source
AI summary
A time-domain inertial sensor comprising: a support structure having an electrode plane parallel to an x-y plane of an x-y-z mutually orthogonal coordinate system, wherein the support structure's largest dimension lies within the x-y plane; a proof mass having a first surface parallel to the x-y plane; wherein the proof mass is springedly coupled to the support structure such that the first surface is separated from the electrode plane by a gap; a driver configured to drive the proof mass to oscillate with respect to the support structure in approximately only the x-direction such that, while oscillating, the gap does not vary significantly; and a first, time-domain, proximity switch disposed to switch from an open state to a closed state each time the proof mass is in a first reference position with respect to the support structure.