Optical Localization Using LED Spectral Signatures

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Solution Overview

Problem

Existing RF-based localization systems face limitations in achieving high accuracy due to multipath fading, especially in indoor environments, and require modifications to existing lighting infrastructure for optical communication technologies like VLP, which hampers commercial availability.

Innovation Solution

A method utilizing unmodified LEDs with unique light signatures detected at predetermined wavelengths, combined with machine learning models, to accurately locate mobile units within environments lit by these light sources, enhancing localization accuracy and integrating with RF information for improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RF-based localization systems are used, then coverage and penetration are improved, but localization accuracy deteriorates due to multipath fading

Engineering Contradiction:

Improvecoverage and penetrationVSAvoidlocalization accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the localization function into two parts: RF systems provide broad coverage and penetration, while optical systems provide high-precision localization. This segmentation allows each system to operate in its optimal performance range without interfering with the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges RF and optical localization systems into a hybrid architecture where RF beacons provide area coverage and optical LEDs provide precise positioning. The mobile device integrates both RF and optical sensors to combine the advantages of both systems, achieving both coverage and accuracy.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If optical communication technology (VLP) is implemented, then localization accuracy is improved, but infrastructure modification requirements increase

Engineering Contradiction:

Improvelocalization accuracyVSAvoidinfrastructure modification requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes existing LED lighting infrastructure serve dual purposes: providing illumination and enabling VLP localization. By using the LED's inherent spectral characteristics as identification signatures, the system eliminates the need for separate localization transmitters or modified LED hardware, achieving multi-functionality from existing components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the LED lights' own spectral properties (emission wavelengths and intensity ratios) as their unique identification signatures. Each LED naturally emits a characteristic spectrum that serves as its fingerprint, eliminating the need for external calibration or modification to create identifiable signals.

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If commercial LED lights are used for VLP, then cost-effectiveness is improved, but spectral variation among LEDs increases system complexity

Engineering Contradiction:

Improvecost-effectivenessVSAvoidspectral variation among LEDs

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent changes the approach from trying to standardize LED spectra to utilizing spectral variations as distinctive features. By measuring the intensity ratio at different wavelengths (e.g., blue vs. green channels), the system converts spectral variation from a problem into a useful identification parameter that distinguishes different LEDs.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system detects and utilizes the color characteristics (spectral composition) of different LEDs as their unique identifiers. By measuring the relative intensity at different wavelengths, the system creates a spectral fingerprint for each LED, turning color variation into a useful localization feature rather than a source of error.

Inventive Principle:

Principle #32Color changes

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 provides accurate and cost-effective indoor location tracking and navigation, improving RF-based localization systems by leveraging existing LED lights, achieving decimetre-level accuracy and enabling seamless integration with IoT devices and smart building management systems.

Implementation Method 1

obtains a plurality of pieces of spectral information of visible light the mobile unit is exposed to, the spectral information being only obtained at a limited number of predetermined wavelength

Methodology Applied

Scientific EffectSpectral detection: Absorption Spectroscopy

Data Source

PatentUS20250020758A1System and method for optical localization

Publication Date: 2025.01.16 KK TOSHIBA

AI summary

A method of detecting a location of a mobile unit in an environment lit by a plurality of light sources, the method comprising, the mobile unit using a light sensor, obtains a plurality of pieces of spectral information of visible light the mobile unit is exposed to, the spectral information being only obtained at a limited number of predetermined wavelength. The method further comprises comparing the determined signature to previously stored signatures of light sources and identifying a light source that has the most similar signature to the determined signature and estimating a current location of the mobile unit as being at or proximate to a known installation location of the identified light source.