Inductive Linear Stroke Sensor With Dual-Period Tracks
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Solution Overview
Problem
Existing sensors using electromagnetic flux sensing elements face challenges in meeting safety-critical application requirements due to issues with sensor quality levels and failure rates, particularly in systems requiring precise position measurement of mechanical elements.
Innovation Solution
A system comprising a target with dual tracks and multiple receiving coils, each aligned with specific features, generating off-phase magnetic field signals to accurately determine the position of the target, which is smaller than the coil periods, reducing errors and improving sensor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single track with single-period coils is used, then the device complexity is reduced, but the measurement precision deteriorates due to errors in position measurement
Solution Approach 1:
The patent divides the sensing system into two separate tracks (first track and second track) with different periodicities. Each track has its own receiving coil that generates signals with different spatial frequencies. This segmentation allows the system to measure position more accurately by combining information from multiple periodicities, resolving the ambiguity that would exist in a single-track system.
Solution Approach 2:
The patent introduces an additional dimension of measurement by using dual tracks with different periodicities instead of a single track. This transforms the problem from one-dimensional position sensing to a two-dimensional sensing approach, where position can be determined more precisely by analyzing signals from both periodicities simultaneously.
2Length of moving object
If the target length is made larger to cover the full stroke range, then the productivity is improved, but the device complexity increases due to larger keep-out length requirements
Solution Approach 1:
The patent changes the periodicity parameters of the receiving coils in the two tracks. By using different periodicities (first period length and second period length), the system can determine position over a larger stroke range without proportionally increasing the keep-out length. The mathematical relationship between the two periodicities allows for extended measurement range while maintaining compact dimensions.
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
The system enhances precision and reduces errors in position measurement, facilitating better control algorithms for safety-critical applications by ensuring the target length is shorter than the coil periods, thus minimizing keep-out length and allowing for more compact integration.
Implementation Method 1
a first receiving coil that is aligned with the first track, the first receiving coil having a first period length, the first receiving coil being configured to sense a first reflected magnetic field that is generated by any of the first features, the first receiving coil being configured to generate a first magnetic field signal in response to the first reflected magnetic field
Data Source
AI summary
A system including: a target having a first track and a second track, a first receiving coil that is aligned with the first track, the first receiving coil having a first period length; a second receiving coil that is aligned with the first track the second receiving coil having a second period length; a third receiving coil that is aligned with the second track the third receiving coil having a third period length; and a fourth receiving coil that is aligned with the second track, the fourth receiving coil having a first period length; and a magnetic field sensor that is configured to generate an output signal that is indicative of a position of the target, wherein the respective target length is less than any of the first period length, the second period length, the third period length, and the fourth period length.