AprilTag-Based Assembly Deviation Correction for 3D Position Monitoring
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Solution Overview
Problem
Existing methods for 3D object restoration, particularly those using cameras, face challenges in accuracy and applicability due to high costs and limitations in texture and color similarity, while AprilTags offer a solution for precise 3D position calculation but require improvement in real-time monitoring of assembly deviations caused by gaps and tolerances.
Innovation Solution
An apparatus and method utilizing AprilTags, Aruco markers, or ARToolKit, combined with a camera and imaging unit, to continuously monitor position and angle variations in X, Y, and Z axes, allowing for real-time correction of assembly deviations by deriving 3D position variation values and transmitting control signals to machining or conveying units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If AprilTag sensing marks are used for real-time monitoring of assembly deviations, then measurement precision and manufacturing precision are improved, but device complexity increases due to the need for imaging units and sensing mark integration
Solution Approach 1:
The patent uses AprilTag sensing marks as visual copies or representations of physical components. These 2D encoded tags contain positioning information that allows the system to track 3D positions and orientations without requiring complex physical measurement devices. The imaging unit captures images of these tag copies to derive position variation values, simplifying the overall measurement system while maintaining high precision.
Solution Approach 2:
The patent replaces traditional mechanical measurement systems with an optical-based image processing system. Instead of using mechanical sensors, encoders, or physical contact measurement devices, the system uses cameras to capture images of AprilTag markers and computationally derives position and orientation data. This substitution reduces mechanical complexity while improving measurement capabilities.
2Measurement precision
If traditional 3D restoration methods using laser or pattern light are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses inexpensive AprilTag markers that can be easily printed or attached to components instead of expensive laser scanners or structured light projectors. These tags are simple 2D visual elements that can be mass-produced at low cost and replaced if needed, providing high-precision 3D positioning information through standard camera imaging without requiring costly specialized equipment.
Solution Approach 2:
The patent replaces active optical systems (laser, pattern light projectors) with passive visual markers. Instead of projecting structured light patterns and capturing their deformation, the system uses pre-encoded AprilTag markers that contain all necessary positioning information in their visual pattern, allowing 3D restoration through image analysis alone without active illumination requirements.
3Device complexity
If Structure From Motion or stereo vision methods are used for 3D restoration, then device complexity is reduced, but measurement precision deteriorates when texture is insufficient or colors are similar
Solution Approach 1:
The patent applies high-contrast, visually distinct AprilTag markers at specific locations on components rather than relying on the natural texture or color of the entire object surface. Each tag has a unique encoded pattern with high visual contrast that ensures reliable detection and measurement, overcoming the limitations of low-texture or monochromatic surfaces that plague traditional SfM and stereo vision methods.
Solution Approach 2:
The patent uses AprilTag markers with distinct color patterns and high-contrast visual encoding. These tags incorporate multiple colors and sharp transitions that provide rich visual information for accurate camera calibration and position detection, eliminating the ambiguity that occurs when objects have uniform color or insufficient texture variations.
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
This approach minimizes assembly deviations and process errors by enabling precise real-time monitoring and correction of position variations, enhancing the accuracy and efficiency of the assembly process and product quality.
Implementation Method 1
an imaging unit which creates an original image by imaging the sensing mark
Data Source
AI summary
An apparatus for correcting a process error includes: a frame; a machining unit formed inside or outside the frame with respect to the frame and performing a predetermined process; a conveying unit formed inside or outside the frame with respect to the frame and performing predetermined conveying; a sensing mark formed on the frame, the machining unit, or the conveying unit; an imaging unit formed inside or outside the frame and creating an original image by imaging the sensing mark; and a measuring unit deriving a 3D position variation value of the frame, the machining unit, or the conveying unit by deriving an image variation value of the sensing mark by analyzing the original image transmitted from the imaging unit imaging the sensing mark formed on the frame, the machining unit, or the conveying unit.