Inductive Proximity Sensing With Ratiometric Current-Voltage Detection
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Solution Overview
Problem
Existing inductive proximity sensors in aircraft systems face issues with nondeterministic results due to variations and overlaps of sensor parameters measured by absolute magnitude, leading to ambiguities and misalignments between sensors and targets over time, causing incorrect status determinations and system malfunctions.
Innovation Solution
Implementing a ratiometric sensing method that measures and processes the operating current and voltage of inductive proximity sensors by dividing the sensor current by the supply voltage, scaling the supply current, and using temperature compensation to eliminate common mode effects and variations, allowing for more accurate status determination and health monitoring without extending the operational range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If absolute magnitude sensing method is used, then the sensing system is simple to implement, but the measurement precision deteriorates due to variations and overlaps of sensor parameters
Solution Approach 1:
The patent changes the sensing parameter from absolute current magnitude to the ratio of current to supply voltage. This parameter transformation eliminates the influence of supply voltage variations and sensor tolerances, thereby improving measurement precision without significantly complicating the sensing system implementation.
Solution Approach 2:
The patent replaces the traditional absolute magnitude measurement approach with a ratiometric measurement system that uses voltage and current signals. This substitution allows for more precise measurements by using electrical signal ratios rather than absolute electrical magnitudes, resolving the contradiction between simplicity and precision.
2Device complexity
If absolute current magnitude is measured, then the sensing electronics are simple, but the reliability deteriorates due to nondeterministic sensor status and ambiguities
Solution Approach 1:
The patent transforms the sensing parameter from absolute current to a ratio of current to supply voltage. This parameter change eliminates common mode effects and supply voltage variations, providing deterministic sensor status determination and improving reliability while maintaining relatively simple sensing electronics through the use of basic voltage and current measurements.
3Measurement precision
If ratiometric sensing method is implemented, then the measurement precision is improved by eliminating common mode effects, but the device complexity increases due to additional measurement and processing requirements
Solution Approach 1:
The patent implements a ratiometric sensing approach where the same voltage and current measurement circuitry serves multiple functions: measuring supply voltage, measuring sensor current, and calculating the ratio to determine sensor state. This multi-functionality improves measurement precision while limiting the increase in device complexity by reusing existing circuit components rather than adding entirely separate measurement systems.
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 proximity sensing by minimizing common mode effects and environmental variations, enabling precise measurement of target positions and sensor health, reducing ambiguities and misalignments, and providing timely health status reporting to aircraft systems.
Implementation Method 1
Alternating current passing through the coil generates a varying electromagnetic field. When a piece of metal target moves into the magnetic flux paths generated by the energized coil, the inductance of and the current flowing through the coil change
Implementation Method 2
measuring and processing the sensing parameters in a ratiometric way... dividing the sensor current by the sensor's supply voltage which produces that operating current
Data Source
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AI summary
Systems and methods for measuring an operating current and an operating voltage of an inductive proximity sensor in an improved manner. The proposed method is to measure and process the sensing parameters in a ratiometric way. A proximity sensing electronics unit receives an input signal from a proximity sensor that was derived by dividing the sensor's current by the sensor's supply voltage which produces that operating current. The division result, i.e., the quotient, is properly scaled to represent the sensor's state. The circuitry ratiometrically determines its operation status by eliminating common mode effects and variations of sensor state thresholds, allowing additional sensing parameters and health status to be measured and monitored without extending the operational range of the sensor.