Hydrogen Sensor Calibration via Neural Network Voltage Profiling
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Solution Overview
Problem
Conventional hydrogen sensors require complex calibration processes to achieve sufficient accuracy, involving numerous measurements at different heating voltages and temperatures, which are influenced by component tolerances and gas components like moisture and oxygen, leading to high measurement uncertainty.
Innovation Solution
A method for calibrating hydrogen sensors using a varying heater voltage profile over time, evaluated with an algorithm, particularly an artificial neural network, to determine a functional relationship between the bridge voltage and hydrogen concentration, reducing the need for extensive calibration and accounting for system variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods with numerous measurements at different heating voltages and temperatures are used, then measurement accuracy is improved, but calibration complexity and measurement time increase
Solution Approach 1:
The patent applies preliminary action by performing comprehensive calibration measurements at multiple heating voltages and temperatures before production. The calibration data is collected in advance under various conditions (different heating voltages UH and temperatures T), and a neural network model is trained beforehand to compensate for component tolerances and environmental influences. This preliminary calibration eliminates the need for complex real-time calibration during production, resolving the contradiction between measurement accuracy and calibration complexity.
Solution Approach 2:
The patent implements feedback through a neural network model that is trained on comprehensive calibration data and then used to compensate for deviations in individual sensors. The model takes into account the specific characteristics of each sensor (such as membrane thickness and electrical resistance) and adjusts the measurement results accordingly. This feedback mechanism allows for high measurement accuracy without requiring complex calibration procedures during production.
2Measurement precision
If measurements are taken at additional heating voltages to increase accuracy, then measurement precision is improved, but measurement time and calibration effort increase
Solution Approach 1:
The patent performs all necessary measurements at multiple heating voltages and temperatures in advance during the calibration phase. The comprehensive dataset collected at different heating voltages (including additional voltages beyond the normal operating range) is used to train a neural network model beforehand. This preliminary action ensures that when the sensor is used in production, no additional measurement time is required, as the model has already learned the relationships from the comprehensive calibration data.
Solution Approach 2:
The patent utilizes parameter changes by varying the heating voltage over a wide range during calibration (including voltages above and below the normal operating voltage) to capture the full behavior of the sensor. These parameter variations are used to train the neural network model, which then can accurately predict hydrogen concentration at the normal operating voltage without requiring additional measurements during production, thus reducing calibration time while maintaining high precision.
3Reliability
If component tolerances are accounted for through extensive calibration, then measurement reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements feedback by using a neural network model that is trained on calibration data from multiple sensors with different component tolerances (membrane thickness, electrical resistance). The model learns to compensate for these individual variations and provides reliable measurements for each specific sensor. This feedback approach allows for high measurement reliability without requiring complex manual calibration procedures during manufacturing, as the model automatically adapts to each sensor's characteristics.
Solution Approach 2:
The patent applies self-service by enabling each sensor to compensate for its own component tolerances through the pre-trained neural network model. During production, the sensor's specific characteristics (such as membrane thickness and electrical resistance) are measured and fed into the model, which then automatically adjusts the measurement results. This self-service approach eliminates the need for complex external calibration procedures, simplifying manufacturing while maintaining high reliability.
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 approach achieves high measurement accuracy with reduced measurement effort, eliminating the need for further calibration in production and allowing for simpler signal evaluation, while accounting for temperature and part-part scattering, thus improving the separation of gas components and reducing voltage uncertainty.
Implementation Method 1
The principle of the heated hydrogen sensor is based on the different thermal conductivities of the gas components involved
Implementation Method 2
a measuring chip with a heated membrane is housed
Implementation Method 3
Various system parameters, such as membrane thickness and electrical resistance, are incorporated into the thermal and electrical system
Data Source
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AI summary
A method for calibrating a sensor (10) for detecting at least one property of a fluid medium (12) in at least one measuring chamber (14), in particular for detecting an H2 content in a measuring gas (16), is proposed, wherein the sensor (10) has a sensor element (18) with at least one heatable membrane (20), wherein the membrane (20) is connected to an electrical measuring bridge (48).The procedure comprises the following steps: applying an electrical heating voltage (UH) to the membrane (20) to heat the membrane (20), varying the heating voltage (UH) over a predetermined period, measuring an electrical bridge voltage (UB) at the measuring bridge (48) over the predetermined period, evaluating the time course of the measured bridge voltage (UB) using an algorithm (60), and determining a functional relationship between the property of a fluid medium (12) and the evaluated time course of the measured bridge voltage (UB).