Gas Sensor Baseline Drift Compensation via Wheatstone Bridge
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Solution Overview
Problem
Gas sensor readings for low explosive limit (LEL) sensors are affected by baseline drift due to mechanical shock and wear, leading to inaccurate measurements, especially when there is no combustible gas present.
Innovation Solution
A method and system that calculate a compensated reading by using a Wheatstone bridge circuit with a detector element and a compensator element, where a working voltage causes the gas to react and a stimulate voltage keeps it inert, allowing for the calculation of a concentration level by accounting for baseline drift through voltage differences in the circuit branches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gas sensor is used to detect combustible gas concentration, then gas detection capability is provided, but baseline drift occurs due to mechanical shock and wear leading to inaccurate readings
Solution Approach 1:
The sensing circuitry is divided into two separate circuit branches: a first circuit branch with a detector element that responds to both baseline drift and gas concentration, and a second circuit branch with a compensator element that responds only to baseline drift. By segmenting the sensing function in this way, the patent isolates the baseline drift component which can then be subtracted from the total signal to leave only the gas concentration measurement, thereby resolving the accuracy-reliability contradiction
Solution Approach 2:
The compensator element acts as an intermediary that experiences the same mechanical shock and environmental conditions as the detector element but does not respond to combustible gas. This intermediary component provides a reference signal for baseline drift that can be used to correct the detector element's readings, eliminating the need for calibration gas and maintaining accuracy under mechanical stress
2Measurement precision
If calibration gas is used to correct baseline drift, then reading accuracy improves, but the system requires additional calibration resources and procedures
Solution Approach 1:
The compensator element enables the sensor system to self-correct for baseline drift automatically during normal operation. By continuously monitoring the compensator element's output, the system automatically compensates for drift without requiring external calibration gas or manual intervention, thereby improving accuracy while reducing system complexity and eliminating calibration resource requirements
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 improves the accuracy of gas sensor readings by eliminating baseline drift without the need for calibration gas, providing reliable detection of combustible gases even in environments with mechanical stress.
Implementation Method 1
A method and system that calculate a compensated reading by using a Wheatstone bridge circuit with a detector element and a compensator element
Implementation Method 2
The detector element comprises a first metal wire coil covered in a catalytic material, and the compensator element comprises a second metal wire coil covered in a non-catalytic material. The working voltage causes the gaseous substance to react on the detector element, and the stimulate voltage causes the gaseous substance to remain inert on the detector element
Data Source
AI summary
Methods, apparatuses, and systems for calculating a compensated reading of a gas sensing apparatus are provided. An example method includes causing a first supply of a working voltage to a sensing circuitry of the gas sensing apparatus, determining a first output of the sensing circuitry, causing a second supply of a stimulate voltage to the sensing circuitry, determining a second output of the sensing circuitry, and calculating a compensated reading of the gas sensing apparatus based at least in part on the first output and the second output.