Inductive Position Encoder Sensing Winding Configuration
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Solution Overview
Problem
Inductive position encoders face challenges in achieving a combination of compact size, high resolution, accuracy, low cost, robustness to contamination, and robustness to misalignments while providing spatially filtered detector signals to reduce harmonic errors.
Innovation Solution
The electronic position encoder incorporates a scale with a periodic pattern of signal modulating elements and a detector portion with sensing elements arranged in specific configurations to generate and respond to changing magnetic flux, featuring shifted sensing element effective areas and spatial filtering to suppress unwanted harmonic components, thereby improving accuracy and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensing element configurations are used, then the encoder structure is simple, but harmonic errors reduce measurement precision
Solution Approach 1:
The sensing element is divided into multiple discrete conductive loops arranged in a specific pattern rather than using a single continuous winding. This segmentation allows selective suppression of harmonic components while maintaining the fundamental measurement signal, thereby improving measurement precision without excessive complexity
Solution Approach 2:
Different sections of the sensing element have different properties - specific conductive loops are positioned at particular locations relative to the scale pattern to selectively respond to certain spatial harmonics. This local differentiation enables targeted harmonic suppression while preserving measurement accuracy
2Measurement precision
If higher resolution is achieved through denser scale patterns, then measurement precision improves, but the encoder becomes more sensitive to misalignments
Solution Approach 1:
The sensing element configuration is designed to dynamically adapt to alignment variations through its distributed loop structure. The multiple loops at different positions provide redundancy that allows the system to maintain reliable operation even when misalignment occurs, preventing total signal loss while preserving high resolution measurement capability
3Reliability
If compact size is reduced, then the encoder becomes more robust, but spatial filtering capability is reduced
Solution Approach 1:
The sensing element uses a two-dimensional arrangement of conductive loops in the y-direction rather than simple one-dimensional windings. This dimensional change enables spatial filtering of harmonic components while maintaining a compact footprint in the measurement direction, achieving both robustness and precision in a compact form factor
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 the encoder's ability to accurately measure relative positions with reduced harmonic errors, offering improved spatial filtering and robustness against misalignments while maintaining economical fabrication and layout.
Implementation Method 1
The field generating coil is configured to generate a changing magnetic flux in the interior area in response to a coil drive signal
Implementation Method 2
Each respective set of sensing elements is configured to provide detector signals which respond to a local effect on the changing magnetic flux
Data Source
AI summary
An inductive position encoder includes a scale, a detector and a signal processor. The scale includes a periodic pattern of signal modulating elements (SME) arranged along a measuring axis (MA) with a spatial wavelength W1. The detector comprises sensing elements and a field generating coil that generates a changing magnetic flux. The sensing elements comprise conductive loops that provide detector signals responsive to a local effect on the changing magnetic flux provided by adjacent SME's. Some or all of the conductive loops are configured according to an intra-loop shift relationship wherein equal “shifted proportions” of a loop are shifted in opposite directions by W1/4K. K is an odd integer. The intra-loop shift relationship can be used to suppress Kth spatial harmonic components in the detector signals, while also overcoming longstanding detrimental layout problems. It combines easily with “loop width” spatial filtering techniques that filter other spatial harmonic signal components.