Inductive Displacement Sensor with Dual-Loop Fine Position Sensing
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Solution Overview
Problem
Inductive displacement sensors with moveable measuring heads face challenges in achieving high resolution and accuracy, particularly in measuring fine displacements, and are sensitive to position and length variations of the measuring loop.
Innovation Solution
The sensor employs two pairs of measuring loops, one triangular and one sinusoidal/cosinusoidal, with symmetric geometric shapes to provide constant output signal summation, enabling independent measurement of coarse and fine displacements, and utilizes a digital evaluation circuit for precise signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single measuring loop is used, then the device complexity is low, but the measurement precision for fine displacements is insufficient
Solution Approach 1:
The measuring system is segmented into multiple measuring loops with different geometric configurations (triangular and sinusoidal/cosinusoidal). Each loop pair is responsible for specific displacement ranges, with the triangular loops handling coarse displacement and sinusoidal loops handling fine displacement, thereby achieving high measurement precision through functional segmentation
Solution Approach 2:
The patent transitions from a single measuring loop to multiple measuring loops arranged in different geometric dimensions and configurations. By adding spatial and geometric dimensions to the measuring loop arrangement, the system achieves enhanced measurement capability for fine displacements while maintaining manageable complexity through systematic design
2Measurement precision
If the measuring head is fixed, then the device complexity is low, but the measurement precision and resolution are reduced
Solution Approach 1:
The measuring head is designed to be moveable or rotatable rather than fixed, allowing dynamic adjustment of its position and orientation. This dynamic capability enables the measuring head to optimize its configuration for different measurement scenarios, achieving submicron resolution through self-regulating functions while the system adapts to various measurement conditions
3Measurement precision
If asymmetric measuring loops are used, then the device complexity is low, but the measurement precision is reduced due to position dependence
Solution Approach 1:
The patent employs symmetric coil arrangements where measuring loops are positioned symmetrically with respect to the measuring head. This symmetry ensures that the output signal remains independent of the measuring head's position and orientation, eliminating position-dependent errors while maintaining manageable system complexity through balanced configuration
Solution Approach 2:
The patent uses measuring loops with different geometric parameters (triangular vs. sinusoidal/cosinusoidal shapes) to achieve different measurement functions. By changing the geometric parameters of the loops, the system achieves position-independent measurement for fine displacements while the triangular loops provide coarse displacement measurement, resolving the contradiction between precision and complexity
4Measurement precision
If analog signal processing is used, then the device complexity is low, but the measurement precision and noise rejection are insufficient
Solution Approach 1:
The patent replaces analog signal processing with digital signal processing in the evaluation circuit. By converting analog measuring signals to digital signals and applying digital processing algorithms, the system achieves enhanced measurement precision, improved noise rejection, and better signal accuracy while managing device complexity through systematic digital circuit design
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 achieves submicron measuring resolution and low noise, with a floating measuring head that is independent of loop length and position, allowing for high accuracy and robustness against environmental fluctuations.
Implementation Method 1
at least one exciter loop, by means of which a magnetic flux can be generated in the measuring head. The magnetic flux penetrates the at least one measuring loop at any point of the longitudinal/rotational displacement of the measuring head, essentially in the region of the measuring head, and induces an electric measuring signal.
Implementation Method 2
The measuring head has a passive resonant circuit which is formed as an outwardly electrically decoupled oscillating circuit and which is excited in correct phase relation by a short voltage pulse after a number of, preferably, 10 to 20 free oscillations.
Data Source
AI summary
An inductive displacement sensor having a magnetically permeable measuring head arranged displaceably and/or rotatably on an elongated support, having at least one measuring loop with a geometric shape changing in response to longitudinal/rotational displacement of the measuring head along the support, and having at least one exciter loop by means of which a magnetic flux can be generated in the measuring head. At least two measuring loops being provided, the first measuring loop formed geometrically in such a way that a response, changing as linearly as possible, to a magnetic excitation of the measuring head emerges with a longitudinal/rotational displacement of the measuring head along the support and the least second measuring loop formed geometrically in such a way that a periodically changing response to a magnetic excitation of the measuring head emerges with a longitudinal/rotational displacement of the measuring head.