Ultrasound Sensor Diaphragm State Detection Using Chirp Excitation
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Solution Overview
Problem
Existing ultrasonic sensors in motor vehicles face challenges in efficiently detecting and quantifying the state of their membranes, which can be affected by conditions such as ice or contaminants, leading to inaccurate sensor data due to divergent readings from additional sensors mounted at different locations.
Innovation Solution
A method involving the application of two distinct frequency-modulated excitation signals, such as up-chirp and down-chirp signals, to the ultrasonic sensor membrane, followed by voltage waveform analysis and comparison with reference parameters to determine the membrane's state, including contamination or ice coverage, using an equivalent circuit model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors are mounted at different locations to accurately predict membrane behavior, then measurement precision is improved, but device complexity increases and sensor data diverges geographically
Solution Approach 1:
The ultrasonic sensor performs self-diagnostics by using its own excitation signal to probe membrane conditions. The evaluation unit analyzes impedance changes and resonance frequency shifts caused by ice or contamination directly at the membrane location, eliminating the need for separate diagnostic sensors mounted at different positions.
Solution Approach 2:
The ultrasonic sensor's excitation signal serves dual purposes: it both drives the membrane for normal ultrasonic operation and acts as a diagnostic probe to detect membrane conditions. The same signal path and evaluation unit are used for both sensing and self-diagnosis, making the system multi-functional without adding separate components.
2Measurement precision
If additional sensors are mounted at different locations to accurately predict membrane behavior, then measurement precision is improved, but reliability decreases due to geographic divergence of sensor data
Solution Approach 1:
The ultrasonic sensor performs self-diagnostics by using its own excitation signal to probe membrane conditions. The evaluation unit analyzes impedance changes and resonance frequency shifts caused by ice or contamination directly at the membrane location, eliminating the need for separate diagnostic sensors mounted at different positions.
3Measurement precision
If the membrane is subjected to multiple excitation signals with different frequency profiles, then measurement precision is improved for determining membrane state, but use of energy increases
Solution Approach 1:
The system uses frequency-modulated excitation signals (chirp signals) that sweep through a range of frequencies rather than using multiple separate sinusoidal signals. This allows the membrane's frequency response to be characterized efficiently in a single continuous excitation, reducing the total energy required compared to multiple discrete frequency measurements.
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 precise and quantitative assessment of membrane conditions, allowing for timely identification of damaged sensors and enabling predictive maintenance, ensuring reliable sensor operation and safer vehicle performance.
Implementation Method 1
a first voltage waveform (U1(F)) is determined, which is induced by the first excitation signal
Implementation Method 2
a membrane of the ultrasonic sensor is excited by ultrasonic waves at a predetermined excitation frequency. Subsequently, a decay frequency is observed
Data Source
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AI summary
The invention proposes a method and an analysis system which can determine a state of a diaphragm (20) of an ultrasound sensor (10) during operation. The diaphragm (20) of the ultrasound sensor (10) is excited with a first excitation signal in a prespecified first frequency profile. On this basis, a first voltage profile (29) is measured, which first voltage profile is dependent on a frequency (F) of the first excitation signal. Analogously, a second voltage profile (31) is ascertained by applying a second excitation signal to the diaphragm (20) and subsequent measurement. These two voltage profiles are shifted such that respective positions of maxima (M1, M2) of the two voltage profiles (29, 31) are approximated to one another in a prespecified frequency range (F'). A third voltage profile (30) is ascertained, which third voltage profile runs between the shifted first and second voltage profiles (29', 31'). On the basis of the third voltage profile (30), electrical parameters (Rp, Rs, Cp, Cs, Lp, Ls) are ascertained by means of a model for continuous excitation of the diaphragm (20) in order to determine the state of the diaphragm (20).