Optical Encoder Template Matching for Accurate Rotation Detection
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Solution Overview
Problem
Existing optical rotary encoders face challenges in achieving high detection accuracy due to the need for high-definition patterns on code plates and precise positioning, which complicates the realization of accurate rotation state detection in robots and printers.
Innovation Solution
An encoder system that uses a scale portion with irregular patterns, an imaging element, and an estimation portion for template matching, allowing for high-accuracy detection of rotation states without requiring high-definition marks by predicting reference images for subsequent template matching, thereby increasing processing speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high definition patterns are formed on the code plate to achieve high detection accuracy, then measurement precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent uses template matching by storing reference images of mark patterns in advance. Instead of requiring high-definition patterns on the code plate, the system captures images of the marks and compares them against pre-stored reference templates to detect rotation states. This copying approach allows accurate detection using simpler, lower-definition mark patterns.
Solution Approach 2:
The patent performs preliminary capture of mark pattern images and stores them as reference templates before actual measurement. By preparing reference images in advance and using them for comparison during operation, the system achieves high detection accuracy without requiring complex real-time processing or high-definition mark patterns.
2Measurement precision
If high definition patterns and precise positioning are required for the code plate, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent replaces the requirement for high-definition manufactured patterns with a copying-based detection method. Reference images of mark patterns are captured and stored as templates, then used for comparison during operation. This allows the code plate to use simpler, easier-to-manufacture mark patterns while maintaining high detection accuracy through image matching.
3Measurement precision
If template matching is performed without predicting the reference image, then measurement precision is maintained, but productivity decreases due to retrieval time
Solution Approach 1:
The patent predicts which reference image template will be needed next based on the current rotation state and movement direction. By anticipating the required template in advance, the system prepares the comparison data before it is needed, eliminating retrieval delays during actual measurement while maintaining accurate template matching for detection precision.
Solution Approach 2:
The patent uses feedback from the current rotation state and movement direction to predict the next required reference image. This feedback mechanism allows the system to anticipate future template needs based on observed motion patterns, optimizing the timing of template preparation and improving processing speed without sacrificing measurement accuracy.
4Measurement precision
If the retrieval region includes the entire captured image, then measurement precision is improved, but productivity decreases due to increased calculation time
Solution Approach 1:
The patent identifies and focuses template matching operations on local regions around the marks rather than processing the entire captured image. By setting retrieval regions specifically around the mark locations where pattern matching is actually needed, the system maintains detection accuracy while significantly reducing the number of pixels that require calculation, thereby improving processing speed.
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 system enables high-accuracy detection of rotation states in robots and printers, improving operational control by reducing the need for high-definition marks and enhancing processing speed through efficient template matching and reference image prediction.
Implementation Method 1
an imaging element that is disposed in the base portion, and images the marks
Implementation Method 2
performs template matching on a captured image in the imaging element by using the reference image, so as to detect positions of the marks
Data Source
AI summary
An encoder includes a base portion, a scale portion that is provided to be relatively movable or rotatable with respect to the base portion, and has three or more marks which are different from each other, an imaging element that is disposed in the base portion, and images the marks, and an estimation portion that selects at least one reference image from among three or more reference images, performs template matching on a captured image in the imaging element by using the reference image, so as to detect positions of the marks, and estimates a movement state or a rotation state of the scale portion with respect to the base portion, in which the estimation portion predicts a reference image to be used for post-template matching on the basis of a result of pre-template matching, and performs the post-template matching by using the predicted reference image.