Stereo Camera Parallax Analysis for Low Position Detection

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Solution Overview

Problem

Existing position detection systems for movable bodies, such as forklifts, face challenges in detecting low positions without improving infrastructure, particularly when navigating areas with height differences, as they rely on external guide wires or complex road analysis.

Innovation Solution

A position detection apparatus equipped with a stereo camera and image processing section that captures and processes images to detect parallax, allowing the identification of low positions by extracting lines and calculating their slopes and intercepts, enabling the detection of road surfaces and steps without requiring infrastructure enhancements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If guide wires are disposed on the road surface for position detection, then the detection reliability is improved, but the infrastructure complexity increases

Engineering Contradiction:
Improveposition detection reliabilityVSAvoidinfrastructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The movable body performs self-detection of its position and low positions using its own imaging device, eliminating the need for external guide wires or infrastructure. The system uses autonomous image processing to detect the road surface and determine low positions, making the detection system self-sufficient without requiring external assistance or infrastructure modification.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical guide wire system with an optical imaging and image processing system. Instead of using physical guide wires that require installation and maintenance, the system uses cameras to capture images and algorithms to detect the road surface and low positions, substituting mechanical infrastructure with optical-electronic detection.

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

2Device complexity

If stereo vision and image processing are used to detect low positions, then the infrastructure requirement is reduced, but the measurement precision challenge increases

Engineering Contradiction:
Improveinfrastructure requirementVSAvoidlow position detection difficulty
Core Design Contradiction:
Device complexityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent transforms the 2D image data into 3D spatial information by detecting the road surface plane equation from multiple image points. This dimensional transformation allows the system to infer depth and elevation information from 2D images, enabling accurate low position detection without requiring complex 3D sensors or infrastructure.

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

Solution Approach 2:

The patent introduces the road surface plane equation as an intermediary model that connects image data to physical position information. By fitting a plane equation to detected road surface points, the system creates a mathematical representation of the road surface that serves as a mediator for calculating low positions, simplifying the detection process while maintaining accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables the forklift to detect low positions and prevent travel obstacles by calculating the distance to steps and determining the capability to traverse height differences, thereby preventing accidents without modifying the environment.

Implementation Method 1

a parallax image acquisition section that acquires a parallax image from an image obtained by the stereo camera

Methodology Applied
Scientific EffectParallax: Parallax

Data Source

PatentEP3633619B1Position detection apparatus and position detection method
Publication Date: 2021.02.24 TOYOTA INDUSTRIES CORP
  • EP3633619B1 patent drawingFigure 1
  • EP3633619B1 patent drawingFigure 2~3
  • EP3633619B1 patent drawingFigure 4

AI summary

A parallax image (dp) in which a parallax is associated with each pixel is acquired from an image captured by a stereo camera (31). The parallax is voted to a two-dimensional matrix of the parallax and a pixel in a vertical direction in the parallax image (dp). A line is extracted from a coordinate system in which an X-axis indicates the parallax and a Y-axis indicates the pixel in the vertical direction. In the case where a first line (L1) and a second line (L2) are detected, an X-coordinate of the start point coordinates (x2, y2) of the second line (L2) is larger than an X-coordinate of end point coordinates (x1, y1) of the first line (L1), and the difference between the slope of the first line (L1) and the slope of the second line (L2) falls within a permissible range, a determination section (41) determines that a low position (R2; G) is present at a position farther from the movable body than a position in real space corresponding to a Y-coordinate of start point coordinates (Fig. 4).