Passive RFID Self-Location Using Phase Variance Tracking

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Solution Overview

Problem

Current mobile device self-location methods using passive radio frequency devices are limited by high costs, complex calibration procedures, and dependence on tag density and type, leading to inaccurate and scenario-dependent results, especially in dynamic environments.

Innovation Solution

A mobile device self-location method using passive radio frequency devices that emits UHF or microwave signals, receives feedback signals, and determines the phase variance to reconstruct the trajectory with high precision, allowing for deterministic positioning without the need for extensive calibration or multiple tags.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RFID-based location systems use a large number of reference tags and lengthy calibration procedures, then location determination becomes possible, but the system complexity and calibration time increase significantly

Engineering Contradiction:

Improvelocation determination capabilityVSAvoidnumber of reference tags and calibration procedures

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the calibration procedure from the RFID location system by using active tags that continuously broadcast their position and identity, removing the need for lengthy calibration processes and multiple reference tags while maintaining location determination capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Active tags perform self-identification and self-location broadcasting, eliminating the need for external calibration systems. Each tag independently provides its position information, allowing the mobile device to determine location without complex external calibration procedures

Inventive Principle:

Principle #25Self-service

2Measurement precision

If optical sensors with sophisticated image processing are used, then location accuracy improves, but computational costs and privacy issues increase

Engineering Contradiction:

Improvelocation accuracyVSAvoidcomputational cost and processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention replaces complex optical image processing systems with simple RFID radio frequency signal processing. Instead of using cameras and sophisticated image algorithms, the system uses RFID tags and basic signal triangulation, dramatically reducing computational costs while maintaining location accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention uses simple, low-cost active RFID tags instead of expensive optical sensors and processing systems. The tags are inexpensive devices that broadcast position information, replacing costly camera systems while achieving comparable or superior location accuracy with minimal computational requirements

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If passive RFID tags are activated only when mobile device passes near them, then system cost is reduced, but location mapping becomes rough and scenario-dependent

Engineering Contradiction:

Improvesystem costVSAvoidlocation mapping accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The invention inverts the traditional passive RFID approach by using active tags that continuously broadcast their position. Instead of waiting for the mobile device to pass near passive tags, the tags actively transmit their location information, enabling continuous and accurate location mapping throughout the entire scenario without being scenario-dependent

Inventive Principle:

Principle #13The other way round (Inversion)

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 precise and cost-effective self-location of mobile devices in various environments with reduced complexity and adaptability, allowing for accurate trajectory tracking using a single passive device, eliminating the need for extensive calibration and probabilistic methods.

Implementation Method 1

A mobile device self-location method using passive radio frequency devices... emits UHF or microwave signals, receives feedback signals

Methodology Applied

Scientific EffectElectromagnetic reflection: Reflection

Data Source

PatentEP3796039A1Mobile device self-location method using at least one passive radio-frequency device

Publication Date: 2021.03.24 UNIV DI PISA

Figure 1~2

AI summary

A mobile device self-location method is provided, which uses at least one passive radio-frequency device (3), implemented in a system (1) including the mobile device (2), the passive device and a processor (4), wherein the mobile device includes at least one antenna (20) configured to emit radio-frequency source signals, the passive device is configured to replicate, with feedback signals, to the source signals and to forward to the mobile device the feedback signals determined by the response of the passive device to the source signals, the processor is designed to at least compare the source signals and the feedback signals, wherein the method comprises moving the mobile device along a trajectory (2a), emitting the source signals, receiving the feedback signals and comparing the feedback signals and the source signals in such a way as to determine the position of the mobile device with respect to the passive device.