3D Nail Recognition and Positioning for Tilt-Aware Decorating

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Solution Overview

Problem

Existing nail decorating machines face errors due to nail tilt angles and height differences, leading to inaccurate nail recognition and increased decorating time, especially when multiple nails are processed.

Innovation Solution

A method involving 3D image processing and point cloud technology to accurately recognize and position nails by obtaining true point cloud coordinates, converting to a calibration coordinate system, and calculating tilt and rotation angles, enabling precise nail positioning for decorating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pre-coating nail surface with nail gel is used for recognition, then recognition can be performed, but nail decorating time increases and steps become cumbersome

Engineering Contradiction:
Improvenail recognition accuracyVSAvoidnail decorating time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts and removes the pre-coating step from the nail recognition process. Instead of requiring nail gel application to enhance contrast, the system uses natural color difference detection algorithms that work directly with the nail's inherent color properties, eliminating the time-consuming preparation step while maintaining recognition accuracy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/chemical approach of applying nail gel to modify nail surface properties with a computational approach using color space transformation and threshold segmentation algorithms that detect nail boundaries based on natural color differences in RGB and HSV color spaces

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If only single nail is printed, then printing process is simple, but rotation angle and tilt recognition is not needed and multiple nails cannot be processed

Engineering Contradiction:
Improveprinting process complexityVSAvoidmulti-nail processing capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements a universal recognition system that can handle both single and multiple nails simultaneously. The algorithm processes all detected nail contours in the image, automatically identifying each nail's position, orientation, and tilt angle, making the system adaptable to various decorating scenarios without requiring different processing modes

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent segments the image into multiple nail regions using threshold-based segmentation and contour detection. Each detected contour represents a separate nail, and the system processes each segment independently to determine its specific rotation and tilt parameters, enabling simultaneous multi-nail recognition and printing

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If 2D mask image is used for nail recognition, then recognition can be performed, but Z-axis depth information is lost causing errors in spraying process

Engineering Contradiction:
Improvenail position recognitionVSAvoiddepth information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent transitions from 2D image processing to 3D point cloud processing by introducing depth information through stereo vision or time-of-flight sensing. The system reconstructs the nail surface as a 3D point cloud, preserving elevation data that enables accurate determination of nail tilt angles and height variations, which are critical for precise spraying control

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4645268A1Method and system for identifying and positioning nails
Publication Date: 2025.11.05 SHANGHAI MEINAIER TECH CO LTD
  • EP4645268A1 patent drawingFigure 1~2
  • EP4645268A1 patent drawingFigure 3~5
  • EP4645268A1 patent drawingFigure 6

AI summary

A method and system for nail recognition and positioning are disclosed. The method includes: S1, acquiring, by a recognition device, first image information of an operating area through photographing, sending the first image information to a target-detecting network to generate corresponding second image information, and comparing to obtain nail mask images after performing segmentation; S2, obtaining true coordinates of a nail point cloud through calculation of an original 3D point cloud and the nail mask images; S3, converting the nail point cloud to a calibration coordinate system, which is determined by locating a printing device below the identification device; S4, traversing each nail to obtain angle information of the nails according to point cloud information of the nails; and S5, projecting point cloud coordinates of each nail to a two-dimensional plane according to external parameters of a camera, and obtaining a deflection angle of each nail. The device performs a calculation on nail mask images and an original 3D point cloud, so as to obtain the real point cloud coordinates of each nail, such that shapes of the nails can be reflected by a plurality of point cloud coordinates.