Eddy Current Sensor Segmented Target Coil Function
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Solution Overview
Problem
Eddy current sensor arrangements for contactless position detection face challenges in tolerance robustness, particularly with changes in distance and tilting, leading to measurement errors due to the dependence of the eddy current effect on distance and requiring multiple sensor coils and conductive traces with complex geometries.
Innovation Solution
A sensor arrangement with a segmented target and eddy current sensor using at least two detection coils that act as either measuring or correction coils, depending on their position, allowing for reduced installation space and increased tolerance robustness, while maintaining high EMC robustness and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensor coils and conductive traces with identical geometry are used for tolerance-robust design, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The target is segmented into first areas with measurement tracks and second areas with correction tracks. The sensor is segmented into multiple detection coils that can be selectively activated. This segmentation allows the system to use only the necessary coils and tracks for each measurement scenario, reducing overall complexity while maintaining precision through the coordinated use of measurement and correction components.
Solution Approach 2:
The detection coils are designed to serve dual functions: they act as measuring coils when positioned over first areas and as correction coils when positioned over second areas. This multi-functionality eliminates the need for separate dedicated measurement and correction coil sets, reducing device complexity while maintaining the tolerance-robust measurement capability.
2Reliability
If multiple sensor coils and conductive traces are used for tolerance robustness, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The system dynamically assigns detection coils to measurement or correction functions based on their position relative to the target areas. This dynamic assignment allows the same physical components to serve different purposes, reducing the total number of components needed and simplifying manufacturing while maintaining reliability through the flexible use of available components.
Solution Approach 2:
The electrical characteristics of detection coils are changed by selectively activating them as measuring or correction coils based on position. This parameter change approach allows the system to adapt its behavior to different measurement conditions using the same hardware, reducing manufacturing complexity while maintaining tolerance robustness.
3Volume of moving object
If detection coils are positioned to cover both measurement and correction areas, then installation space is reduced, but measurement precision may be compromised
Solution Approach 1:
The measurement and correction functions are segmented into different spatial areas on the target. Detection coils are positioned to cover both areas but are selectively activated based on which area they are currently over. This spatial segmentation allows compact positioning while maintaining measurement precision through context-aware coil activation.
Solution Approach 2:
The detection coils automatically determine their own function (measuring or correction) based on their position relative to the target areas. This self-service mechanism eliminates the need for complex external control logic and allows the same coils to serve different functions, achieving compact design without compromising precision.
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 solution provides a compact, cost-effective, and tolerant sensor arrangement with improved EMC robustness, capable of accurately determining relative positions with reduced measurement errors across varying distances and tilts, utilizing a shared segmented geometry for measurement and correction tracks.
Implementation Method 1
The measuring coil induces an eddy current in the electrically conductive measuring track, which leads to a change in the inductance of the measuring coil
Implementation Method 2
The measuring coil induces an eddy current in the electrically conductive measuring track
Implementation Method 3
whose resonant frequency changes as a result
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to a sensor assembly (1) for detecting a displacement in a contactless manner, comprising a target (10), which has a measurement value transmitter (14) that moves along a measurement path (M) and comprises at least one electrically conductive measurement track (MS1, MS2, MS3, MS4), and an eddy current sensor (20) with a measurement value sensor (22) which comprises at least two detection coils (A, B, C, D). The measurement value sensor (22) is arranged at a distance from the measurement value transmitter (14) and in a relatively movable manner along the at least one electrically conductive measurement track (MS1, MS2, MS3, MS4), and the measurement value sensor at least partly covers the measurement track. At least one of the detection coils (A, B, C, D) acts as a measurement coil, the measurement signal of which is evaluated by an evaluating and control unit (5) in order to detect a displacement. The invention also relates to a method for determining the position of a sensor (20) relative to a target (10) of a sensor assembly (1) for detecting a displacement in a contactless manner. The measurement value transmitter (14) has at least one electrically conductive correction track (KS11, KS12, KS21, KS22, KS31, KS32, KS41, KS42) which is arranged together with the at least one measurement track (MS1, MS2, MS3, MS4) within a common geometry. First regions (x1) with at least one measurement track (MS1, MS2, MS3, MS4) and second regions (x2) with at least one correction track (KS11, KS12, KS21, KS22, KS31) alternate periodically along the measurement path (M). At least one of the detection coils (A, B, C, D) acts as a correction coil, the measurement signal of which is evaluated by the evaluating and control unit (5) in order to correct the displacement detection. The action of the individual detection coils (A, B, C, D) as measurement coils or as correction coils varies along the measurement path (M), wherein the evaluating and control unit (5) assigns a detection coil (A, B, C, D) the measurement coil action if the corresponding detection coil (A, B, C, D) is positioned over a first region (x1) or the correction coil action if the corresponding detection coil (A, B, C, D) is positioned over a second region (x2).