Linear Position Sensor Triangular Tracks
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Solution Overview
Problem
Existing linear position sensors face challenges in achieving high resolution and absolute positioning over long distances due to degradation of resolution with increased dynamic range and the introduction of harmonics from non-linear magnetic flux, particularly with sine-like coil shapes.
Innovation Solution
A linear position sensor design utilizing a combination of triangular-shaped and discrete incremental step measuring tracks, where the triangular tracks provide fine resolution and the incremental step tracks provide coarse resolution, with sensor coils aligned to change inductance based on position, minimizing harmonic interference and maintaining linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple turns of measuring coil are used to improve resolution, then measurement precision is improved, but the sensor cannot provide absolute position information and requires complex sine-like shapes that are difficult to fabricate
Solution Approach 1:
The patent divides the measuring system into two separate segments: a slider with simple coil turns and a scale with periodic conductive patterns. This segmentation allows the complex functionality to be distributed, making each component easier to manufacture while maintaining high measurement precision through the interaction of the segments.
Solution Approach 2:
The patent transitions from a one-dimensional coil structure to a two-dimensional interaction between the slider coils and the scale patterns. By adding the dimensional aspect of the scale's periodic conductive regions, the system achieves absolute position information and improved resolution without requiring complex three-dimensional coil windings.
2Measurement precision
If sine-like coil shapes are used to improve measurement, then resolution is improved, but higher harmonics are introduced that degrade sensor response
Solution Approach 1:
The patent extracts the periodic pattern function from the coil structure and places it on the scale instead. The slider coils remain simple and generate minimal harmonics, while the scale's conductive patterns provide the periodic variation needed for measurement, thereby separating the harmonic-generating function from the measurement function.
Solution Approach 2:
Instead of creating complex sine-like coil shapes, the patent uses simple coil turns that copy the periodic information from the scale's conductive patterns. The scale acts as a template that defines the measurement periodicity, allowing the coils to remain geometrically simple while still achieving high-resolution measurements.
3Ease of manufacture
If fixed geometric shapes are used in the measuring system, then manufacturing is simplified, but resolution degrades as dynamic range increases
Solution Approach 1:
The patent introduces dynamic periodic patterns on the scale that interact with the static coils on the slider. The effective measurement geometry changes dynamically as the slider moves relative to the scale, allowing the system to maintain high resolution across a large dynamic range while keeping the actual manufactured shapes simple and static.
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 enhances resolution and dynamic range, allowing for accurate absolute positioning over longer distances with reduced harmonic interference, improving sensor linearity and signal-to-noise ratio.
Implementation Method 1
The measuring coil induces Eddy currents in the conductive track, which leads to an inductance change of the measuring coil
Implementation Method 2
The measuring coil induces Eddy currents in the conductive track
Implementation Method 3
the inductance of the sensor coils or the coupling between the sensor coils is dependent on the position of the measurement path
Data Source
Figure 1.a
Figure 1.b
Figure 2~3
AI summary
The present application describes a linear position sensor (1) intending to solve the problem of achieving long linear position sensors with improved resolution and absolute positioning. For that, the linear position sensor (1) comprises an element (3) where sensor coils (7), (8), (9), (10) are disposed, and a partly electrically conductive element (2), both elements are moved relative to each other in a direction along a measurement path S0 to S2. Said partly electrically conductive element (2) comprises measuring tracks of two typologies, triangular shape type (5) and a discrete incremental step type (4), (6) providing each one fine and coarse resolution measurements respectively. The use of linear tracks - triangular shape - allows not only to minimize the degradation of the resolution of the sensor as the dynamic range of the sensor increases, but also allows to improve the sensor linearity due to the reduction of the harmonics that degrade the sensor response.