Vision-Based 6-DOF Displacement Estimation for Precast Bridge Assembly
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Solution Overview
Problem
The existing cast-in-place method for bridge construction is inefficient due to the need for re-casting concrete when desired quality is not obtained, causing additional costs and traffic disruptions, while the Precast Concrete method requires precise assembly of precast members, which is limited by reliance on gestures and voice communication between crane operators and workers.
Innovation Solution
A vision-based localization method is used to estimate the 6-DOF relative displacement of dynamic members with respect to fixing members, employing image processing to extract feature points from markers and applying homography or probability-based location estimation methods to achieve precise assembly, even in conditions of occlusion or blur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cast-in-place method is used for bridge construction, then the construction can be done on-site with flexible scheduling, but additional costs are incurred due to re-casting and traffic disruptions occur
Solution Approach 1:
The bridge construction is divided into multiple precast concrete members that are manufactured separately in controlled environments and then assembled on-site. This segmentation allows quality control during manufacturing while maintaining construction flexibility through modular assembly.
Solution Approach 2:
Concrete members are precast in advance in controlled factory conditions before being transported to the construction site. This preliminary action ensures consistent quality through standardized manufacturing processes while enabling efficient on-site assembly.
2Productivity
If the Precast Concrete method is used, then construction time is reduced and quality management is improved, but precise assembly becomes difficult due to reliance on gestures and voice communication
Solution Approach 1:
The manual communication-based assembly process is replaced with an automated vision-based localization system that uses cameras and image processing to detect marker positions and calculate 6-DOF displacement, providing precise real-time guidance for member assembly.
Solution Approach 2:
Markers are introduced as intermediary objects attached to precast members, serving as visual references for the vision system to accurately determine member positions and orientations during assembly, thereby achieving precise alignment without relying on human communication.
3Manufacturing precision
If vision-based localization with markers is used for assembly guidance, then assembly precision is improved, but the system fails when markers are occluded or images are blurred due to member movement
Solution Approach 1:
The system transitions from static marker detection to dynamic tracking that accounts for member movement during assembly. The vision system continuously captures and processes images to update displacement calculations in real-time, maintaining precision even when members are in motion.
Solution Approach 2:
Instead of relying on a single clear image, the system uses multiple image frames and applies image processing techniques to extract feature points even from partially obscured or blurred images, ensuring continuous operation during dynamic assembly processes.
Data Source
AI summary
A method for estimating 6-DOF relative displacement using vision-based localization and apparatus therefor are disclosed. A method for estimating 6-DOF relative displacement may include acquiring images of a first marker attached to a fixing member and a second marker attached to a dynamic member for assembling to the fixing member by using a camera, extracting a feature point of the first marker and a feature point of the second marker through image processing for the acquired images, and estimating 6-DOF relative displacement of the dynamic member for the fixing member based on the extracted feature point of the first marker and feature point of the second marker.