Inductive Sensor Target Patterns for Linearity
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Solution Overview
Problem
Inductive displacement sensors face challenges such as sensitivity to assembly inaccuracies, presence of conductive parts, lack of linearity, precision, and robustness issues, as well as fragility, particularly in industrial environments, limiting their effectiveness and measurement range.
Innovation Solution
The design incorporates a target with multiple conductive patterns and a transducer with overlapping secondary windings, optimized for angular displacement measurement, which enhances linearity and robustness by adjusting the target-transducer distance and modifying the electromagnetic field distribution, reducing linearity errors and sensitivity to parasitic disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional inductive displacement sensor is used, then the sensor can perform contactless measurement, but the sensor exhibits sensitivity to assembly inaccuracies and lack of linearity
Solution Approach 1:
The target is divided into multiple conductive patterns (first set with N patterns, second set with N+r patterns) distributed along a zone. Each pattern interacts with the electromagnetic field independently, and their combined effect provides a more robust and linear measurement signal, reducing sensitivity to assembly inaccuracies.
Solution Approach 2:
The patent introduces a new dimension by overlaying two sets of conductive patterns with different periods (Dtot/N and Dtot/(N+r)) on the same target surface. This multi-layered pattern arrangement creates a more complex electromagnetic interaction that improves linearity and reduces sensitivity to parasitic disturbances.
2Length of stationary object
If the measurement range is extended, then the sensor can measure larger displacements, but the linearity deteriorates
Solution Approach 1:
The measurement zone is segmented into multiple conductive patterns distributed along a zone of dimension Dtot. By using N patterns with period Dtot/N and N+r patterns with period Dtot/(N+r), the sensor achieves extended measurement range while maintaining linearity through the combined effect of multiple patterns.
Solution Approach 2:
The patent changes the parameters of the conductive patterns by using two different periods (Dtot/N and Dtot/(N+r)) and different numbers of patterns (N and N+r). This parameter variation allows the sensor to maintain linearity across an extended measurement range.
3Ease of manufacture
If the sensor structure is simplified, then the manufacturing becomes easier, but the precision and robustness decrease
Solution Approach 1:
The target with multiple conductive patterns serves multiple functions: it provides the measurement signal, compensates for assembly inaccuracies, and reduces sensitivity to parasitic disturbances. This multi-functionality is achieved within a single target structure, maintaining ease of manufacture while improving precision.
4Object-affected harmful factors
If the target-transducer distance is increased, then the sensitivity to parasitic disturbances is reduced, but the measurement signal weakens
Solution Approach 1:
The patent merges the effects of multiple conductive patterns (N patterns of first type and N+r patterns of second type) to create a combined measurement signal. This merging of multiple signal sources compensates for the signal weakening that occurs at increased target-transducer distances while maintaining reduced sensitivity to parasitic disturbances.
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 configuration improves the linearity and robustness of inductive displacement sensors, extending their measurement range and reducing sensitivity to assembly inaccuracies and environmental factors, making them more suitable for industrial applications.
Implementation Method 1
The transducer includes a primary winding, or inductor, suitable for producing an alternating electromagnetic field, and at least one secondary winding at the terminals whereof an alternating voltage is induced, also referred to as electromotive force or EMF, in the presence of the electromagnetic field produced by the primary winding
Implementation Method 2
The present application relates to the technical sub-field of eddy-current sensors, wherein an electromagnetic field generated by an inductor is established differently according to the presence and the arrangement of movable (with respect to the inductor) conductive parts in the vicinity of the inductor
Data Source
AI summary
A target for an inductive displacement sensor is provided, including a plurality of conductive patterns distributed along a zone having a dimension Dtot in a direction, the patterns being defined by the overlay of at least a first set of elementary periodic patterns having a period approximately equal to Dtot/N, including N first elementary conductive patterns of a dimension approximately equal to Dtot/2N in the direction, regularly distributed along the zone, and of a second set of elementary periodic patterns having a period approximately equal to Dtot/(N+r), including N+r second elementary patterns of a dimension approximately equal to Dtot/2(N+r) in the direction, regularly distributed along the zone, where N is an integer greater than or equal to 2 and r is a positive integer, different to zero and less than or equal to N−1, wherein first and second elementary conductive patterns overlap at least partially.