RFID Tag Velocity Tracking Using Radar-Person Motion Matching

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Solution Overview

Problem

Existing RFID systems in retail stores face unreliability in determining the location of RFID tags due to interference, which affects merchandise tracking and theft detection.

Innovation Solution

A method and system that combines radar and RFID signals to determine movement vectors of both persons and RFID tags, using time-of-flight and phase measurements to associate the tags with individuals, thereby enhancing tracking accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RFID systems use RSSI to determine the location of RFID tags, then the system can track merchandise and detect potential theft, but the location determination becomes unreliable due to interference

Engineering Contradiction:
Improvelocation determination reliabilityVSAvoidinterference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent combines radar technology with RFID systems to create a hybrid tracking system. The radar component provides interference-resistant location and movement data that complements the RFID tag tracking, thereby resolving the unreliability caused by interference in pure RFID RSSI-based location determination.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The radar system acts as an intermediary that provides alternative location and movement verification data. By measuring the movement vector of the person carrying the RFID tag independently of RFID signal strength, the radar mediates the location determination process and eliminates reliance on interference-prone RSSI measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the system tracks customers exiting the retail store and RFID tag locations separately, then the system can identify potential theft, but the association between customers and tags remains uncertain leading to false alarms

Engineering Contradiction:
Improvetag-customer association accuracyVSAvoidtheft detection reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The radar movement vector measurement serves as an intermediary verification mechanism. By independently measuring the physical movement of the customer carrying the tag, the radar provides corroborating evidence that links the customer to the tag, reducing false associations and improving theft detection reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses radar movement data to feedback and verify the association between customers and RFID tags. When the radar-detected customer movement matches the expected movement of a tagged item, this feedback confirms the association, thereby reducing false alarms in theft detection.

Inventive Principle:
Principle #23Feedback

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

Improves the reliability of merchandise tracking and theft prevention by accurately associating RFID tags with individuals, reducing false alarms and enhancing security.

Implementation Method 1

determining a first movement vector of the person based on the reflected radar signal

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 2

receiving at least one reflected radar signal in response to the at least one incident radar signal reflected from a person

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

The RFID tag may respond by backscattering one or more backscattered RFID signals

Methodology Applied
Scientific EffectBackscattering: Scattering

Data Source

PatentEP4217911B1Methods and apparatuses for determining tag velocity
Publication Date: 2026.03.18 SENSORMATIC ELECTRONICS CORP
  • EP4217911B1 patent drawingFigure 1
  • EP4217911B1 patent drawingFigure 2
  • EP4217911B1 patent drawingFigure 3

AI summary

Aspects of the present disclosure include methods, systems, and non-transitory computer readable media for transmitting at least one incident radar signal, receiving at least one reflected radar signal in response to the at least one incident radar signal reflected from a person associated with the RFID tag, determining a first movement vector of the person based on the reflected radar signal, transmitting at least one incident RFID signal, receiving at least one backscattered RFID signal from the RFID tag, determining a second movement vector of the RFID tag based on at least one phase measurement of the at least one backscattered RFID signal, and determining whether the RFID tag is associated with the person based on the first movement vector and the second movement vector.