The geta sandals a footprint location tracking system
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The GETA Sandals: A Footprint Location Tracking System. Kenji Okuda, Shun-yuan Yeh , Chon-in Wu, Keng-hao Chang, and Hao-hua Chu National Taiwan University. What is GETA?. a kind of the traditional Japanese sandals. Outline. Motivation Related works Basic idea

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The geta sandals a footprint location tracking system

The GETA Sandals: A Footprint Location Tracking System

Kenji Okuda, Shun-yuan Yeh, Chon-in Wu, Keng-hao Chang, and Hao-hua Chu

National Taiwan University


What is geta
What is GETA?

  • a kind of the traditional Japanese sandals


Outline
Outline

  • Motivation

  • Related works

  • Basic idea

  • Design, implementation and evaluation

    • (three versions try and error)

  • Conclusion

  • Current works


Motivation
Motivation

  • Infrastructure cost (barriers for the user)

    (deployment, calibration, maintain)

    • Active Badge: IR receivers

    • Active BAT: Ultrasonic receivers + RF

    • Cricket: Ultrasonic beacons + RF

    • RADAR: WiFi network

    • Smart floor: pressure sensors

  • Goal

    • Infrastructure free

      (not succeed so far in this paper-> low infrastructure)

    • High accuracy


Related works
Related Works

  • Lee et al. proposed a method

    • by recognizing a sequence of incremental motions.

      • E.g. 5 steps north followed by 14 steps east.

    • Only can tell from place to place

      • e.g. living room, bedroom

  • Point research provides a vehicle self-tracking system


Basic idea of foot print approach
Basic idea of Foot-print Approach

( 180, 200 )

S5

S4

Sp

S3

S2

Sp=S1+S2+S3+S4+S5

S1

( 0, 0 )


How to sum up those vectors mathematically

(x2, y2)

θ

Coordinate system 2

(xc2, yc2)

(xc1, yc1)

Coordinate system 1

How to sum up those vectors mathematically

Coordinate system 1’

Need coordinate transformation for each left foot step.

(x1, y1)



Design version i

Ultrasonic Receivers

Ultrasonic Transmitters

Bottom view

side view

Design version I


Why using two transmitters

Can be rotated!!

d3

d4

d1

d2

Why using two transmitters

P2 (Unknown)

(fixed)

T1

fixed

P1 (known)


Why using two transmitters1
Why using two transmitters

Can Not be rotated any more !

P2 (determined)

T2

T1

P1 (known)


Problems of design i
Problems of Design I

  • Poor accuracy!

    • The interference of the signals from two transmitters.

      • Measures the incorrect vectors

      • Miss-detection of the user’s steps

      • All the calculations become failure.

  • Can not distinguish the user is moving forward or backward!


Design version ii

Orientation Sensor

Pressure sensor

Ultrasonic Transmitter

Ultrasonic Receivers

Bottom view

side view

Design version II



Two main error sources

P1

Real path

Calculated path

Error Displacement

Two Main Error Sources

Fig1. Ultrasonic device err

Fig2. Orientation sensor err

θerr

P2

P1

Real path

Calculated path

Error Displacement

Error

P2

Steps


The solution of design ii

Passive RFID tag

The solution of design II

Adds a RFID reader in the GETA and put some tags in the environment.

Calculated Path of the user

Real Path of the user


Design version iii

Orientation Sensor

RFID Reader

Pressure Sensor

Ultrasonic Receivers board (with 2 Ultrasonic receivers)

Ultrasonic transmitter

Design version III


Hardware sensors of design iii
Hardware Sensors of Design III

  • Pressure sensors

    • Phidgets

  • Ultrasonic device

    • NAVINote (an electronic pen product)

    • Resolution : 0.2 mm

  • Orientation sensor

    • InterSense InterTrax2

    • Resolution : 0.02 degree

  • RFID Reader

    • SkyeTek M1

    • Read range: ~5cm


Design iii performance evaluation

The positioning error under different tag density over the walking distance.

Design III Performance Evaluation


Conclusion
Conclusion walking distance.

  • A interesting self tracking method.

  • Low infrastructure cost.

  • The error of the orientation dominants our system accuracy.

  • Still have some limitations

    • E.g. climbing the stairs, walking crossover..


Current works
Current Works walking distance.

  • Increase the accuracy

    (reducing the orientation error)

  • Solve the obstruction problem

  • Going down/up stair problem

  • Enhance the wearability (wireless)


Thank you
Thank you walking distance.

Questions?

or send me E-mail

[email protected]

Thank you !


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