RFID Phase Angle Tracking for Accurate Object Detection

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Solution Overview

Problem

RFID systems face challenges in accurately tracking objects due to signal interference and noise in complex environments, making it difficult to determine if a tag has moved between rooms or is present in the correct location.

Innovation Solution

An object tracking system using an RFID reader with antennas positioned at entranceways, combined with entry/exit sensors and a processor that performs entrance, exit, and audit readings, and analyzes phase angle changes to determine if a target RFID tag is moving or stationary, thereby improving tracking accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If RFID reader detects tags in multiple rooms, then coverage area is improved, but tracking accuracy deteriorates

Engineering Contradiction:

Improvedetection coverage areaVSAvoidtag location detection accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The system divides the detection space into multiple zones by positioning RFID readers at specific entranceways. Each reader monitors a specific zone, and the system correlates tag detections across multiple readers to determine which room a tag is in. This segmentation allows broad coverage while maintaining location precision through multi-point verification.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system introduces an intermediary processing layer that correlates signals from multiple RFID readers and entry/exit sensors. This intermediary system resolves ambiguities by analyzing patterns across multiple detection points, determining whether a tag detected in one room has actually moved or is merely within the reader's coverage area.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If multiple RFID tags are used in close proximity, then tracking capability is improved, but signal noise increases

Engineering Contradiction:

Improvenumber of tracked objectsVSAvoidsignal noise and interference

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The system segments the signal processing by assigning different time slots and frequency channels to different readers and tags. This allows multiple tags to be tracked simultaneously without overwhelming interference, as the system processes signals in organized segments rather than as a chaotic whole.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system uses feedback from multiple detection points to verify tag presence and eliminate false positives. When a tag is detected, the system cross-references this with detections from adjacent readers and entry/exit sensor data to confirm actual presence, filtering out noise from nearby tags through pattern recognition.

Inventive Principle:

Principle #23Feedback

3Reliability

If RFID reader operates continuously, then detection reliability is improved, but energy consumption increases

Engineering Contradiction:

Improvedetection reliabilityVSAvoidreader energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system implements periodic detection cycles rather than continuous operation. RFID readers are activated at scheduled intervals and triggered by entry/exit sensor events. This periodic operation maintains detection reliability by regularly monitoring tag positions while significantly reducing energy consumption compared to continuous operation.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system performs preliminary actions by pre-positioning readers at strategic locations and pre-configuring detection parameters based on expected traffic patterns. Entry/exit sensors trigger detection sequences in advance of actual tag movements, allowing the system to maintain high reliability while operating readers only when needed rather than continuously.

Inventive Principle:

Principle #10Preliminary action

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

The system enhances the accuracy of RFID tag tracking by reducing signal noise and interference, allowing for reliable detection of tag movement and presence in specific locations, even in complex environments.

Implementation Method 1

The basic operation of the RFID Reader involves the reader generating a radio frequency signal, having the signal 'activate' the RFID tags, and the reader receiving the unique reflected signals from the RFID tags

Methodology Applied

Scientific EffectRadio frequency signal generation and reflection: Electromagnetic Induction

Implementation Method 2

an entry/exit sensor capable of sensing entrance and departure of an individual through the entranceway

Methodology Applied

Scientific EffectSensor detection of entrance and departure:

Implementation Method 3

monitoring the phase angle of a target RFID tag; and (iii) returning an indicator of whether the target RFID tag is or is not moving based at least in part on whether the phase angle has changed

Methodology Applied

Scientific EffectPhase angle detection: Phase Modulation

Data Source

PatentUS9836936B1Object tracking system

Publication Date: 2017.12.05 C & A ASSOCIATES INC

AI summary

An object tracking system including an RFID reader having at least one antenna positioned along an entranceway of an object storage facility. A processor communicates with RFID reader and runs software to perform the steps of: (i) monitoring the phase angle of a target RFID tag; and (iii) returning an indicator of whether the target RFID tag is or is not moving based at least in part on whether the phase angle has changed.