Non-Contact Rotational Speed Measurement Using Camera and Image Processing
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Solution Overview
Problem
Current methods for measuring the speed of rotating or reciprocating machinery components, such as external tachometers and stroboscopes, require contact or proximity to the machine, are cumbersome, and do not efficiently utilize digital photography for non-contacting torsional vibration measurements.
Innovation Solution
A system and method using a camera to record motion and apply image processing algorithms to determine the speed of rotation or reciprocation without contact, utilizing gear wheels or patterned tapes for torsional vibration measurements, allowing for instantaneous speed and vibration analysis within a single field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external tachometers or stroboscopes are used to measure machine speed, then speed measurement capability is achieved, but device complexity and operational complexity increase
Solution Approach 1:
The patent combines the speed measurement function with the existing vibration analysis camera system. The same camera that records mechanical vibrations is used to capture images of the marked shaft, eliminating the need for separate tachometer or stroboscope equipment. This merging of functions reduces device complexity while maintaining measurement capability.
Solution Approach 2:
The camera system is made multi-functional by enabling it to perform both vibration analysis and speed measurement tasks. By processing images of the marked shaft alongside vibration data, the single camera system achieves universal functionality for both diagnostic purposes without requiring additional specialized instruments.
2Measurement precision
If reflective tape or mechanical discontinuities are applied to the shaft, then speed measurement accuracy is improved, but ease of operation deteriorates due to machine stopping requirements
Solution Approach 1:
The marked shaft is prepared in advance during normal machine operation or during routine maintenance, so that when vibration analysis is needed, the shaft is already marked and ready for measurement. This preliminary action eliminates the need to stop the machine at the moment of diagnostic need, improving ease of operation while maintaining measurement accuracy.
3Object-affected harmful factors
If laser-based tachometers or stroboscopes are used, then non-contact measurement is achieved, but ease of operation worsens due to synchronization requirements
Solution Approach 1:
The patent merges the imaging function with the vibration analysis function, using the same camera for both purposes. This eliminates the synchronization complexity between separate imaging devices and vibration analysis equipment, as they are inherently synchronized when using the same sensor system.
Solution Approach 2:
The system uses feedback from the vibration analysis process itself to guide the speed measurement. By analyzing the same data stream and using the marked shaft images captured during vibration recording, the system automatically determines speed without requiring manual synchronization adjustments, simplifying operation.
4Measurement precision
If specialized speed measurement instruments are used, then speed measurement capability is achieved, but productivity decreases due to additional setup time
Solution Approach 1:
The patent merges speed measurement and vibration analysis into a single integrated process using one camera system. This eliminates the need for separate setup procedures for different instruments, reducing setup time and improving productivity while maintaining accurate speed measurement capability.
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
Enables efficient, non-contact measurement of rotational speed and torsional vibrations with high accuracy, reducing setup time and costs by using a single camera for both speed and vibration analysis, and providing reliable data with minimal time delay.
Implementation Method 1
the light intensity present at the same pixel in each frame is reflected from different angular positions on the shaft as it rotates
Implementation Method 2
apply specialized processing algorithms to identify the speed. This process is much simpler and does not require the expense of a tachometer instrument
Data Source
AI summary
Present embodiments pertain to systems, apparatuses, and methods for analyzing and reporting rotational or reciprocating movements and speed of rotation or reciprocation in mechanical structures, machines, and machine components, through the use of an acquired video recording representing a plurality of cycles of motion, by measuring intensity values of a subset of pixels contained in a region of interest within the video recording in a plurality of frames of the video recording, thereby calculating a speed of rotation or reciprocation of the structure, machine or machine component.