Pantograph Displacement Measurement Using Dynamic Template Scaling
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Solution Overview
Problem
The existing methods for measuring pantograph displacement using a line sensor camera face challenges in maintaining accurate pattern-matching processing, especially at varying camera elevation angles, which can lead to resolution differences and failed pattern matching, affecting the detection of hard spots in trolley wires.
Innovation Solution
The solution involves a device and method that utilize a calibration method to find pixel resolution, divide images into sections, and perform pattern-matching processing with scaled templates, allowing for accurate detection of the marker's pixel position and reducing noise by limiting the processing range and adjusting the template shifting pitch based on correlation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pattern-matching processing is performed on the entire input image, then the marker position can be detected, but the processing time becomes excessively long
Solution Approach 1:
The input image is divided into multiple sections based on the correlation map, with pattern-matching processing performed independently on each section. This segmentation approach reduces the computational burden on each processing unit while maintaining overall detection accuracy, effectively resolving the contradiction between comprehensive detection and processing time.
Solution Approach 2:
A correlation map is generated before the actual pattern-matching processing to identify high-correlation regions where the marker is likely to be located. This preliminary action guides the subsequent pattern-matching process to focus only on relevant areas, avoiding unnecessary computation in low-correlation regions and significantly reducing processing time.
2Adaptability or versatility
If the camera elevation angle varies, then the inspection can be performed from different positions, but the resolution differences cause pattern-matching to fail
Solution Approach 1:
The template used for pattern-matching is dynamically scaled according to the camera elevation angle. When the elevation angle changes, the template size is automatically adjusted to compensate for the resulting resolution differences, ensuring that pattern-matching accuracy is maintained across various camera positions and angles.
Solution Approach 2:
The processing approach changes based on the correlation map values, which reflect the impact of camera elevation angle variations. High-correlation regions use standard pattern-matching, while low-correlation regions undergo different processing or are excluded, allowing the system to adapt to varying camera angles while maintaining overall measurement precision.
3Measurement precision
If the template shifting pitch is small, then the pattern-matching accuracy is high, but the processing time increases
Solution Approach 1:
Instead of performing pattern-matching with fine pitch across the entire image, the system applies correlation-based region identification first to locate potential marker areas. Pattern-matching with appropriate pitch is then performed only in these identified regions, achieving sufficient accuracy without the computational cost of exhaustive fine-pitch searching across the whole image.
Data Source
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AI summary
Since an image processing unit (5A) for determining the acceleration of a pantograph by processing the image of a marker captured by a line sensor camera (2) comprises a input image creating unit (5a) for creating an input image, a template setting unit (5b) for setting a template, an image diving unit (5c) for dividing the input image, a template enlarging/reducing unit (5d) for enlarging/reducing the template, a pattern matching unit (5e) for detecting the pixel position of the marker in the input image, a pantograph displacement calculating unit (5f) for converting the pixel position of the marker into the actual displacement of the pantograph, a filtering unit (5g) for smoothing the displacement of the pantograph, and an acceleration output unit (5h) for outputting the acceleration of the pantograph; the accuracy of the pattern matching is improved.