Sensor Element Control Device for Accurate Fault Diagnosis
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Solution Overview
Problem
Existing physical quantity sensors face challenges in fault diagnosis due to changes in drive amplitude levels caused by temperature changes or aging, which can affect detection accuracy and require the use of electrostatic coupling capacitance differences for diagnosis, potentially degrading sensor performance.
Innovation Solution
A sensor element control device that generates a diagnostic signal with a detuning frequency, superimposed on the drive signal, to excite the detection unit without relying on electrostatic coupling capacitance differences, allowing for fault diagnosis while minimizing impact on detection accuracy, even when drive amplitude levels change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic coupling capacitance difference is used for fault diagnosis, then fault diagnosis capability is improved, but detection accuracy deteriorates due to drive amplitude level changes
Solution Approach 1:
The patent introduces an artificial impedance as an intermediary element connected between the drive electrode and detection electrodes. This artificial impedance serves as a mediator that enables fault diagnosis by creating a controllable signal path, while the detuning frequency diagnostic signal ensures that the diagnosis process does not rely on electrostatic coupling capacitance differences, thereby maintaining detection accuracy even when drive amplitude levels change.
Solution Approach 2:
The patent utilizes frequency parameter changes by employing a detuning frequency diagnostic signal that differs from both the drive frequency and detection frequency. This frequency parameter differentiation allows the system to perform fault diagnosis independently of drive amplitude variations, resolving the contradiction between diagnostic capability and detection accuracy.
2Duration of action of stationary object
If drive amplitude level changes occur due to temperature or aging, then sensor operation continues, but detection accuracy is affected
Solution Approach 1:
The patent implements a dynamic fault diagnosis approach by continuously monitoring the sensor element's response to detuning frequency diagnostic signals. This dynamic monitoring capability allows the system to adapt to changing drive amplitude levels caused by temperature variations or aging, maintaining detection accuracy throughout the sensor's operational lifespan without requiring static calibration.
3Reliability
If electrostatic coupling capacitance difference method is used, then fault diagnosis is enabled, but additional complexity is introduced to the system
Solution Approach 1:
The patent achieves multi-functionality by using the same sensor element structure for both normal detection operations and fault diagnosis. The detuning frequency diagnostic signal methodology allows the system to perform both functions without requiring separate dedicated diagnostic hardware structures, thereby reducing overall system complexity while maintaining fault diagnosis capability.
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 fault diagnosis of sensor elements, such as disconnections or defects, with reduced influence on detection accuracy, and maintains reliable performance across varying drive amplitude levels.
Implementation Method 1
a drive unit and a detection unit, wherein the drive unit has a drive frequency and the detection unit has a detection frequency
Implementation Method 2
a frequency at which the amplitude of the drive unit is maximum (the resonance frequency of the drive unit) and a frequency at which the amplitude of the detection unit is maximum (the resonance frequency of the detection unit)
Implementation Method 3
a diagnostic signal generation circuit that generates a diagnostic signal having a frequency component corresponding to a detuning frequency which is a difference frequency between a drive frequency
Implementation Method 4
a detection unit that outputs a signal based on a change in a physical quantity
Data Source
AI summary
A sensor element control device which is connectable to a sensor element including a drive unit and a detection unit, includes a drive circuit that outputs a drive signal to the drive unit; a detection circuit that generates a detection signal based on a signal output from the detection unit; a diagnostic signal generation circuit that generates a diagnostic signal having a frequency component corresponding to a detuning frequency which is a difference frequency between a drive frequency which is a frequency at which the drive unit vibrates and a detection frequency which is a frequency at which the detection unit vibrates; and a fault diagnosis circuit that performs fault diagnosis based on a signal output from the detection unit when the diagnostic signal is superimposed on the drive signal.