Real-Time RFID Localization Using RSS

Kirti Chawla, Christopher McFarland, Gabriel Robins, Connor Shope

Presenter: Christopher McFarland [cem8u@virginia.edu]

Background

• The necessity for locating objects• Limitations of current solutions:– Expensive equipment– Nontrivial computational processing– Unrealistic constraints

Objective• Simple! To locate objects in a given environment

• Criteria for a successful system:– Adaptive– Scalable– Accurate– Fast– Realistic

Why RFID?

• Scalable• Wide range of environments• Remove unrealistic constraints?• Deliver next generation of localization services

Sneak Peek

• Our proposed solution• How?

A Key Insight

• Ideal tag-reader pairs unlock higher performance

• Problem– Brands of tags have variable performance

• Solution– Select tag brands based on performance

Real-Time Localization Framework

Real-Time Localization Framework

• Problem– Tags of the same brand have variable sensitivities

• Solution– Bin tags based on their sensitivity

• Problems– RF signal variability renders the Friis Eqn. useless– Environmental effects affecting RSS

Real-Time Localization Framework

Real-Time Localization Framework

Friis Eqn.Friis Eqn. General Form Eqn.

RSS = CDE

General Form Eqn.

RSS = CDE

[Alien, Tag-14]

RSS = 3246.76D-0.89

[Alien, Tag-14]

RSS = 3246.76D-0.89

[ThingMagic, Tag-10]

RSS = -53.17D0.29

[ThingMagic, Tag-10]

RSS = -53.17D0.29

• Solution– Inspired by the Friis Equation

• Solution– Model RSS decay with respect to tag-reader

distance and tag orientation

Real-Time Localization Framework

• Proposed future work– Careful use of reference tags?– Auto-calibration routines– Real-time environmental information

• Where we’re currently at

Real-Time Localization Framework

Creating a Realistic Deployment

Antenna

Mobile Robot with onboard reader

and multi-tag

RFID Reader

Backend Host

TabletInternetInternet

Some Results

Black Actual location

Blue Reported for [ThingMagic, Tag 10] [0.3—1.2m], 0.75m avg*

Red Reported for [Alien, Tag 14] [0—1.14m], 0.57m avg**Ranges and averages include outliers

Have we met the criteria?

• Adaptive• Scalable• Accurate• Fast• Realistic

Real-Time RFID Localization Using RSS

Kirti Chawla, Christopher McFarland, Gabriel Robins, Connor Shope

Presenter: Christopher McFarland [cem8u@virginia.edu]