Video Camera Active Region for High-Speed Rotational Speed Measurement
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Solution Overview
Problem
Existing methods for determining the rotational speed of machine components using video recordings are limited to relatively low rotational speeds due to the requirement of high-resolution images and low frame rates, making them unsuitable for a broad range of rotational speeds.
Innovation Solution
A method that configures the video camera to select a small active region covering only a portion of the detector's pixels, increasing the frame rate to enable the determination of higher rotational speeds, particularly by using a high-resolution camera already integrated for other purposes, such as shaft alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution camera detector is used to obtain accurate angular position data, then measurement precision is improved, but the frame rate decreases due to the large number of pixels requiring readout time
Solution Approach 1:
The detector is divided into an active region and inactive regions. Only the active region, which covers the marked region of the rotating component, is read out to generate image data. This segmentation allows the system to maintain measurement precision by focusing on the relevant area while significantly reducing the total number of pixels processed, thereby increasing frame rate.
Solution Approach 2:
The method extracts and processes only the necessary portion of the detector output - specifically, image data from the active region covering the marked region. By taking out only the relevant data needed for rotational speed determination and discarding data from inactive regions, the system achieves high frame rates without sacrificing the precision needed for accurate angular position measurement.
2Manufacturing precision
If the entire detector is read out to maintain high resolution, then image quality is preserved, but the time required for readout increases, limiting the measurable rotational speed range
Solution Approach 1:
The detector readout is segmented into essential and non-essential regions. The active region is identified and isolated for readout, while other regions are excluded. This segmentation reduces readout time proportionally to the ratio of active region size to total detector size, enabling the system to capture high-speed rotations while preserving sufficient image resolution for accurate measurement.
3Productivity
If a small active region is selected from the detector, then the frame rate increases, but the resolution for angular position determination may be reduced
Solution Approach 1:
The active region is strategically positioned and sized to cover the marked region of the rotating component with sufficient resolution. The local quality of the active region is optimized to provide adequate pixel density for accurate angular position determination, while the global reduction in processed pixels (compared to reading the entire detector) achieves the required frame rate. This local optimization ensures measurement precision is maintained in the critical measurement zone.
Data Source
AI summary
A method for determining a rotational speed of a rotatably mounted component of a machine is disclosed, wherein image data of a marked region of the machine component are obtained in the form of a plurality of frames via a video camera, and the image data are evaluated, in order to determine the periodicity of the rotation of the machine component from the change over time of the image data in the frames of the machine component. The video camera is configured by selecting an active region for obtaining the image data from the total number of pixels of the video camera, in which an observation area is imaged, which is passed through by the marked region during the rotation of the machine component, wherein the active region comprises only a portion of the total number of pixels of the video camera, to increase the frame rate correspondingly.