Arc Encoder Tracks for Compact High-Resolution Position Measurement
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Solution Overview
Problem
Existing measuring instruments face challenges in achieving a desirable combination of compact size, high resolution, accuracy, and robustness to contamination, particularly in encoders used for measuring arc motions.
Innovation Solution
The measuring instrument incorporates an electronic position encoder with a movable portion that rotates in an arc motion, utilizing a movable encoder portion and a fixed encoder portion, each with distinct angular spatial steps, to provide absolute positioning and improved measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional encoder is used to measure arc motion, then the encoder can provide measurement capability, but it cannot achieve both compact size and high resolution simultaneously
Solution Approach 1:
The patent transitions from a conventional linear encoder configuration to an arc-shaped encoder track that conforms to the rotational motion path. By arranging scale elements and detector elements along an arc rather than a straight line, the encoder utilizes the dimensional space of rotation to achieve compact packaging while maintaining high resolution through the arc's curvature radius and element spacing design.
Solution Approach 2:
The encoder track is designed with a curved arc geometry that matches the rotational motion of the movable portion. This curvature allows the encoder to fit within a compact radial space while providing sufficient track length for high-resolution measurement through the relationship between arc length, radius, and angular displacement.
2Volume of moving object
If the encoder track is made compact, then the device size is reduced, but the measurement accuracy may be compromised
Solution Approach 1:
The patent employs different angular spatial steps for different portions of the arc track. The first portion has a smaller angular spatial step for high-resolution measurement in the critical range, while the second portion has a larger angular spatial step. This parameter variation allows the encoder to maintain measurement accuracy where needed while reducing overall device size.
Solution Approach 2:
The arc track is divided into multiple portions with different characteristics. The first arc portion corresponds to a first angular range with finer resolution, while the second arc portion corresponds to a second angular range with coarser resolution. This segmentation allows the compact encoder to provide high accuracy for the most critical measurement range while maintaining overall compactness.
3Reliability
If traditional encoder designs are used, then manufacturing is straightforward, but robustness to contamination is insufficient
Solution Approach 1:
The patent incorporates a protective cover or housing structure that encloses the detector elements and scale elements, creating a sealed environment that protects against contamination from dust, moisture, or other environmental factors. This protective shell approach maintains robustness while allowing the encoder to be manufactured using standard enclosure techniques.
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 enhances the measuring instrument's performance by providing compact size, high resolution, and robustness to contamination, while maintaining accurate measurements even in small angular movement ranges.
Implementation Method 1
The field generating portion is configured to generate changing magnetic flux in response to drive signals
Data Source
AI summary
A measuring instrument includes a movable portion configured to rotate in an arc motion about a pivot portion, and an electronic position encoder configured to measure an absolute relative position between a detector portion and a scale portion, one of which forms part of the movable portion. In the detector portion, first and second scale element portions of first and second track portions are arc-shaped and parallel to each other. In the scale portion, first signal modulating scale elements are disposed along a first scale element portion according to a first signal modulating element angular spatial step θWSME1 and second signal modulating scale elements are disposed along a second scale element portion according to a second signal modulating element angular spatial step θWSME2 that is different than the first signal modulating element angular spatial step θWSME1.