Rail Bolt Inspection Using Laser Light Sectioning
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Solution Overview
Problem
Existing railway inspection systems face challenges in accurately detecting loose fastening and joint-bar bolts due to limitations in obtaining three-dimensional information, contamination, rust, and difficulties in distinguishing bolt states from ballast or cable disturbances, especially during high-speed railcar operations.
Innovation Solution
A range image obtaining system equipped with a laser slit light source and a two-dimensional image imaging device, capable of generating high-density range images by calculating distances from light sectioning images, which are then processed to display height information as gray scales or colors, allowing for accurate inspection of rail fastening devices and joint bars during railcar operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If visual inspection by maintenance persons is used, then inspection can be performed with simple equipment, but inspection accuracy and reliability deteriorate due to human error and subjectivity
Solution Approach 1:
The patent replaces manual visual inspection with an automated optical measurement system. A laser projector projects a laser line onto the bolt, and a line sensor detects the reflected light to automatically measure bolt height and detect looseness, eliminating human subjectivity and error.
Solution Approach 2:
The patent introduces a laser line as an intermediary measurement reference. The laser line projects a reference pattern onto the bolt, and the line sensor uses this reference to accurately measure bolt height and detect changes indicating looseness, providing an objective measurement standard.
2Productivity
If inspection is performed during high-speed railcar operation, then productivity and preventive maintenance capability improve, but measurement precision deteriorates due to railcar vibration and movement
Solution Approach 1:
The patent performs measurement reference establishment beforehand by projecting the laser line to create a stable reference pattern on the bolt before the railcar movement significantly affects the measurement. This preliminary action allows the system to capture bolt height data even during high-speed operation.
Solution Approach 2:
The patent adapts the measurement system to dynamic conditions by using the laser line projection method that creates a reference pattern resilient to vibration. The system captures images at multiple positions and uses image processing to extract accurate measurements despite railcar movement and vibration during operation.
3Device complexity
If simple lighting is used, then device complexity is reduced, but image quality and measurement precision deteriorate due to insufficient illumination and shadows
Solution Approach 1:
The patent applies lighting locally and specifically where needed - the laser projector targets the bolt and fastening device area with a focused laser line, providing intense local illumination that enhances contrast and visibility of measurement features without requiring complex general lighting systems.
Solution Approach 2:
The patent uses the laser line's specific wavelength and the reflected light's properties to create high-contrast imaging. The laser line appears as a bright distinct pattern against the darker background of the track environment, enabling clear detection and measurement without complex lighting arrangements.
4Ease of manufacture
If manual inspection methods are used, then equipment cost is reduced, but inspection reliability and safety deteriorate due to the risky nature of maintenance persons making rounds
Solution Approach 1:
The patent enables the inspection system to perform measurements automatically during normal railcar operation without requiring dedicated maintenance personnel to physically access the track. The railcar itself becomes the inspection platform, eliminating the safety risks associated with manual track inspection while maintaining operational efficiency.
Solution Approach 2:
The patent replaces the mechanical process of maintenance persons physically inspecting bolts with an automated optical measurement system mounted on the railcar. The line sensor and laser projector automatically detect and measure bolt conditions, eliminating human exposure to safety risks while providing consistent, repeatable measurements.
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 precise detection of bolt looseness and abnormalities in fastening devices and joint bars, reducing the risk of accidents by providing detailed three-dimensional shape data and facilitating preventive maintenance without manual oversight.
Implementation Method 1
a laser slit light source disposed within a plane perpendicular to a tread of a rail and emits a laser slit light within the plane perpendicular to the tread
Implementation Method 2
a two-dimensional image imaging device which is disposed to have an angle with respect to the plane perpendicular to the tread and obtains a light sectioning image generated based on the laser slit light
Data Source
AI summary
A range image obtaining system for a track includes a laser slit light source disposed within a plane perpendicular to a tread of a rail and emits laser slit light within the plane; a two-dimensional image imaging device which is disposed to have an angle with respect to the plane perpendicular to the tread of the rail and obtains a light sectioning image generated from the laser slit light; and an image signal processing device for generating a range image based on a distance from the two-dimensional image imaging device based on the light sectioning image.