3D Marker Detection for Parameter-Free Robot Teaching

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Solution Overview

Problem

Existing marker detection systems require complex camera parameter settings to determine three-dimensional coordinates from two-dimensional images, necessitating cumbersome preparations.

Innovation Solution

A marker detection apparatus that utilizes a 3D camera to detect markers by detecting three-dimensional planes, projecting point group data onto two-dimensional planes, and performing pattern matching to calculate three-dimensional coordinates without requiring prior camera parameter settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a two-dimensional camera is used to detect a marker, then the device complexity is reduced, but camera parameters must be set in advance which increases the preparation time and operational complexity

Engineering Contradiction:
Improvecamera system complexityVSAvoidmarker detection preparation
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

A coordinate conversion table is introduced as an intermediary between the two-dimensional camera image and the three-dimensional space coordinates. This table pre-stores the correspondence relationships, allowing the system to directly convert image coordinates to space coordinates without complex real-time calculations or camera parameter settings, thus simplifying the operation while maintaining accuracy

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The coordinate conversion table is prepared in advance through calibration processes that establish the mapping between two-dimensional image coordinates and three-dimensional space coordinates. This preliminary action eliminates the need for complex camera parameter settings during actual marker detection operations, reducing preparation time and operational complexity

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If camera parameters are set in advance to calculate three-dimensional positions, then measurement precision is improved, but the device complexity and preparation requirements increase

Engineering Contradiction:
Improvemarker position accuracyVSAvoidcamera parameter configuration
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of performing complex real-time three-dimensional coordinate calculations requiring precise camera parameters, the system creates a coordinate conversion table that copies and stores the spatial correspondence relationships in advance. This table serves as a lookup reference that maintains measurement precision while eliminating the need for complex camera parameter configurations

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The complex mechanical/mathematical calculation system based on camera parameters and three-dimensional coordinate geometry is replaced with a simplified lookup system using the pre-prepared coordinate conversion table. This substitution maintains measurement accuracy while significantly reducing device complexity and configuration requirements

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

Data Source

PatentEP4177838B1Marker detection apparatus and robot teaching system
Publication Date: 2025.08.06 DAIHEN CORP
  • EP4177838B1 patent drawingFigure 1
  • EP4177838B1 patent drawingFigure 2
  • EP4177838B1 patent drawingFigure 3

AI summary

Provided is a marker detection apparatus able to easily detect the position of a marker and a robot teaching system using the same. A marker detection apparatus includes: a three-dimensional plane detection unit that detects a three-dimensional plane serving as a plane in a three-dimensional space on a basis of point group data acquired by a 3D camera; a two-dimensional plane image generation unit that projects point group data constituting the detected three-dimensional plane in a perpendicular direction based on the three-dimensional plane, thereby generating a two-dimensional plane image; a marker detection unit that detects a marker from the generated two-dimensional plane image; and a marker position calculation unit that, for the detected marker included in the two-dimensional plane image, calculates three-dimensional coordinates on the three-dimensional plane.