Bridge Bolt Axial Force Imaging for Non-Rotational Loosening
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Solution Overview
Problem
Existing bolt loosening detection technologies in bridges are inadequate for identifying non-rotational loosening caused by factors like preload loss, embedment effect, material fatigue, and environmental changes, as they rely on rotational measurements or are costly and time-consuming.
Innovation Solution
A method and device that captures images of bridge bolts, identifies pre-calibrated feature points, and calculates bolt axial force through dimensional calibration and displacement analysis, allowing non-destructive measurement and identification of non-rotational loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic axial force measurement method is used to obtain accurate bolt axial force, then measurement precision is improved, but measurement time increases significantly due to exhaustive measurement of large number of bolts
Solution Approach 1:
The patent uses image copying technology to capture bolt images and extract feature points, creating a digital representation of the bolt's physical state. This allows rapid analysis of multiple bolts simultaneously without physical contact, reducing measurement time while maintaining precision through digital image processing and comparison with standard images
Solution Approach 2:
The patent replaces the mechanical ultrasonic measurement system with an optical imaging system. By substituting mechanical contact-based ultrasonic waves with non-contact optical imaging, the system achieves rapid parallel measurement of multiple bolts, significantly reducing measurement time while maintaining measurement capability through image analysis algorithms
2Ease of operation
If tapping measurement method is used to detect bolt loosening, then ease of operation is improved, but measurement precision deteriorates due to reliance on operator skill and lack of quantitative results
Solution Approach 1:
The patent replaces the mechanical tapping method with an optical imaging system. By substituting mechanical impact and acoustic analysis with optical image capture and digital processing, the system eliminates operator skill dependency while providing objective, quantitative measurement results through automated image analysis algorithms
Solution Approach 2:
The patent introduces image processing algorithms as an intermediary between the measurement action and result evaluation. The system captures images, extracts feature points, compares them with standard images, and automatically determines bolt tightness status, removing the need for operator interpretation while providing precise, quantifiable results
3Ease of operation
If image measurement technology based on rotation angle detection is used, then ease of operation is improved, but measurement precision deteriorates as it cannot detect non-rotational loosening
Solution Approach 1:
The patent analyzes local feature points on the bolt surface rather than relying on overall rotation angle. By examining specific local characteristics such as the positions of bolt head features, nut features, and their relative distances, the system can detect subtle changes including non-rotational loosening that would be invisible to rotation-based methods
Solution Approach 2:
The patent transitions from one-dimensional rotation angle measurement to two-dimensional spatial position analysis of multiple feature points. By measuring the relative positions and distances between feature points in the image plane, the system detects bolt state changes in multiple dimensions, including non-rotational loosening that affects feature point spacing without causing rotation
Data Source
AI summary
Disclosed herein is a bolt axial force measurement method, device, apparatus, and readable storage medium, the method comprises steps of: capturing an image of a bridge bolt; identifying an outer edge of a nut, a centroid of the nut, and a circular position of a laser spot in a captured image of the bridge bolt; projecting a calibration laser spot onto a bolt plate and obtaining a current frame as a bolt-detection image; performing dimensional calibration on the bolt-detection image and determining a displacement of each of the pre-calibrated feature points; calculating a bolt axial force value based on the displacement. The solution captures images of the bridge bolts and analyzes positions of each of the pre-calibrated feature points in the images; thus, the bolt axial force can be measured non-destructively, and non-rotational loosening of bolts can be identified.