Physical Quantity Sensor Self-Diagnosis via Angular Velocity Vibration
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Solution Overview
Problem
Physical quantity sensors with acceleration and angular velocity sensors housed in a common case face accuracy issues due to pressure fluctuations, leading to incorrect processing in applications like vehicle control, as they lack the capability to self-diagnose their detection environment.
Innovation Solution
Incorporating a self-diagnostic unit that monitors the vibration of the angular velocity sensor's vibrating element and a package structure with an airtight chamber for the acceleration sensor, allowing for self-diagnosis of the detection environment by detecting changes in pressure and vibration states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the acceleration sensor and angular velocity sensor are housed in a common case with different pressure environments, then each sensor can operate in its optimal pressure condition, but the system cannot self-diagnose detection environment changes caused by leakage
Solution Approach 1:
The patent introduces a feedback mechanism where the angular velocity sensor's detection output is monitored to infer the pressure state of the housing space. When leakage occurs and pressure changes, the angular velocity detection signal changes accordingly, providing feedback about the detection environment. This allows the system to self-diagnose leakage conditions by analyzing changes in the angular velocity sensor's output characteristics without requiring separate pressure sensors.
Solution Approach 2:
The system uses the angular velocity sensor's own detection function to serve a dual purpose: not only detecting angular velocity but also monitoring the detection environment (pressure changes) in the housing space. By analyzing changes in the vibrating element's behavior, the system self-diagnoses leakage conditions, eliminating the need for separate diagnostic components and enabling autonomous environmental monitoring.
2Measurement precision
If the acceleration sensor is hermetically sealed in an airtight chamber, then the acceleration sensor maintains atmospheric pressure for accurate detection, but leakage at the airtight chamber causes undetected pressure fluctuations
Solution Approach 1:
The patent uses the angular velocity sensor as an intermediary device to indirectly monitor the pressure state of the housing space. Instead of directly measuring pressure or adding complex pressure sensing mechanisms to the acceleration sensor package, the system leverages the angular velocity sensor's sensitivity to pressure changes as a mediator to detect leakage conditions. This intermediary approach provides leakage detection without complicating the acceleration sensor's hermetic seal structure.
3Measurement precision
If the housing space is set to vacuum pressure for the angular velocity sensor, then the vibrating element can vibrate freely with minimal air damping, but pressure fluctuations from leakage reduce detection reliability
Solution Approach 1:
The patent replaces direct mechanical pressure monitoring with an indirect monitoring approach using the angular velocity sensor's electrical output signals. Instead of adding mechanical pressure sensors or complex sealing mechanisms, the system substitutes the monitoring function with analysis of the angular velocity sensor's electrical detection output, which naturally responds to pressure-induced changes in the vibrating element's behavior. This substitution maintains the vacuum environment while enabling leakage detection.
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
Enables accurate self-diagnosis of the detection environment, preventing incorrect processing by determining abnormal conditions in both acceleration and angular velocity sensors, thus ensuring reliable sensor data usage.
Implementation Method 1
an angular velocity sensor provided with a sensing portion having a vibrating element that vibrates in a predetermined direction
Implementation Method 2
a cap portion is arranged in a sensor portion where the sensing portion is formed and the sensing portion is hermetically sealed in an airtight chamber defined between the sensor portion and the cap portion
Implementation Method 3
it is preferable that the acceleration sensor detects acceleration under an atmospheric pressure at which air damping (flow resistance of gas) is high
Data Source
AI summary
A physical quantity sensor includes a detection unit outputting a detection signal corresponding to a vibration of a vibrating element in an angular velocity sensor, and a self-diagnostic unit self-diagnosing a detection environment of an acceleration sensor and the angular velocity sensor on a basis of the detection signal outputted by the detection unit.