Tracking Device Using Stereo and ToF Cameras for Accurate Positioning

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Solution Overview

Problem

Existing tracking systems using camera images cannot accurately determine the distance of a person from the camera, limiting the precision of movement tracking.

Innovation Solution

A tracking device employing intelligent cameras that measure distance using methods like stereo cameras or Time of Flight (ToF) and process the data to calculate polar coordinates, converting them into global coordinates for accurate position determination, while correcting for potential errors in distance measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If camera images are used for tracking, then the tracking system can monitor person's location, but the distance information from the camera to the person cannot be determined

Engineering Contradiction:
Improvepositional accuracyVSAvoiddistance information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent combines multiple measurement methods (stereo camera and ToF camera) with traditional 2D image processing to obtain both distance information and position information. The stereo camera provides depth data through triangulation, the ToF camera measures flight time of light, and these are integrated with the 2D camera images to create comprehensive 3D position tracking with accurate distance measurement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces intermediate calculation steps to derive distance information from available measurements. By calculating polar coordinates (distance and angle) from the combined camera data and then converting to global coordinates, the system creates an intermediary representation that bridges the gap between 2D image data and 3D position information.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If distance measurement is integrated with image processing, then tracking accuracy is improved, but errors in distance data may affect tracking precision

Engineering Contradiction:
Improvetracking accuracyVSAvoiddistance data accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements feedback mechanisms by continuously monitoring the consistency between distance measurements from different methods (stereo camera and ToF camera) and adjusting the tracking calculations accordingly. The system uses the relationship between polar coordinates and global coordinates to verify and correct distance measurements, ensuring that errors in one measurement method do not significantly degrade overall tracking accuracy.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent prepares for potential measurement errors by having multiple independent distance measurement methods ready (stereo camera and ToF camera). This redundancy acts as a cushion against errors in any single method, allowing the system to cross-validate measurements and maintain reliable tracking even when one measurement source provides inaccurate data.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 high-accuracy tracking of a person's movement by integrating distance measurement with image processing, improving positional accuracy and handling errors in distance data to maintain tracking precision.

Implementation Method 1

measures a distance from the intelligent camera to the person

Methodology Applied
Scientific EffectTime of Flight: Time of Flight

Data Source

PatentEP3736734B1Tracking device and tracking method
Publication Date: 2024.11.13 TOSHIBA TEC KK
  • EP3736734B1 patent drawingFigure 1
  • EP3736734B1 patent drawingFigure 2
  • EP3736734B1 patent drawingFigure 3

AI summary

A tracking device includes an interface connectable to cameras, each acquiring an image and determining an object location within the image, a distance therefrom, and a time; a memory storing first coordinates indicating a camera location with respect to a reference point in a facility, and a first direction towards which each camera faces; and a processor, upon receipt of the location, the distance, and the time, calculating a second direction from the camera to the object, calculating second coordinates indicating an object location with respect to the camera location, calculating and storing with the time third coordinates indicating an object location with respect to the reference point. When locations calculated from the images acquired by the first and second cameras are associated with the same time, the processor calculates a distance therebetween, and when the distance falls within a predetermined range, recalculates the object location based on the locations.