RFID Portal Test at the Wireless Habitat Test Bed

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RFID Portal Test at the
Wireless
Habitat
Test Bed


Engineering Directorate

Avionic Systems Division



Andrew Chu/NASA







July 2
8
,
2010




National Aeronautics and Space
Administration

Lyndon B. Johnson Space Center

Houston, Texas 77058
-
3696


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2


1

Introduction

Radio Frequency Identification (RFID) technology has matured to a level that can be used
reliably to support
NASA operations in space and ground segments
. The
Electronic

Product
Code
(EPC) Global Class 1 Generation 2
(C1G2)
standard has
found
wide
spread use throughout
commercial and gover
nm
e
n
t sectors
. Readers, printers, and tag labels from many manufacturers
operate interchangeably with good performance

using the C1G2 s
tandard
. To
demonstrate the
use of RFID in a habitat portal scenario, a Cargo Transfer Bag
(CTB)
currently used for the
Space Shuttle and International Space Station Programs has been outfitted with RFID
-
tag
ged
items

and tested with a
n

RFID portal set up
at an entrance of the
Wireless
Habitat Test Bed
located at the Johnson Space Center
B
uilding 14 high

bay.

2


Wireless
Habitat Test Bed

The habitat structure

of the
Wireless
Habitat Test Bed is a
horizontal cylinder

constructed of ¼
inch aluminum skin.
The cylinder measures 10 feet in diameter and 20 feet in length.
The
aluminum end

caps of the cylinder each contain an aluminum door. The habitat is fitted with a
raised floor of tiles with metal plate backing. Channels at three depths on both cylindric
al walls
provide a method to build out walls
,

cabinets and supports for mounted equipment.
The
inner
walls are made of
1/8” thick
Kydex supp
orted by vertical uni
struts. Outside of both doors
are

a
landing and stairwell made of aluminum.

Figure
1

and
Figure
2

show the habitat structure.


Figure
1
. External vi
ew of the habitat structure
and
portal 1.

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3





Figure
2
. Interior arrangement of the habitat looking out portal 1.

3

Portal setup

A
n

RFID portal
exists at

both doors of the habitat.
Each
portal consists of a
n
Ultra

H
igh
Frequency (UHF)
Impinj Speedway reader and four circularly polarized antennas purchased
through Impinj. Only portal

1

was used for this test. The Speedway reader has part number IPJ
-
R1000
-
USA1M and serial number 37008290063.
The four antennas
,

two e
ach of S9028PCL
and S9028PCR,
were manufactured by Cushcraft
. One or more sensors can be used to trigger
the reader to start reading tags. For this test, a
24
” x 60”

pressure sensing mat was placed at the
edge of the landing to initiate tag reading. The

mat and the two external antennas can be seen in

Figure
1
. One antenna is mounted above the door hinge and the other antenna is mounted on the
landing rail by the d
oor.

The inside antennas are hidden behind the wall in
Figure
2
.
Figure
3

shows the two internal antennas before the walls are installed.

The Speedway reader is installed
below the floor tiles inside the habitat.

A laptop computer running the Speedway Multireader
software a
pplication is used to control and record the tags rea
d by the reader.

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4



Figure
3
. Location of the interior RFID antennas

of portal 1
.

4

Pantry
CTB

The CTB comes in four sizes with the half size bag being the most common. The outside
dimensions of th
e

half size CTB
are

approximately 10” x 17” x 9.5” (L x W x H).

The pantry
CTB is filled with personal hygiene items and office supplies. One RFID tag is placed on the
outside of the CTB to identify the CTB. Similar items inside the CTB are bagged together in
Ziplock bags.

In most cases, RFID tags are placed on individual items inside the Ziplock bags
(item level tagging) as well as on the Ziplock bag itself (bag level tagging). The mixture of
items inside the CTB includes metal foil bags and gel tubes
,

which
tend
to

be di
fficult for

RFID
interrogation
. Previous experience with the pantry CTB has shown which items should be
tagged with general versus specialized tags

that are

designed for application on metal and
liquid/gel items.
Appendix A contains a list of the 52 tags

associated with the pantry CTB.
Appendix B shows in layers
the “standardized” packing arrangement of the CTB
.

The standard
packing order is an arbitrary
orderly
packing of the CTB without regard to the interaction of the
items and tags.

Both standard a
nd random packing configurations are tested.

5

Portal testing

The Speedway reader
at portal
1
was set to output
30 dBm
to all four antennas

(switched
sequentially)
, i.e., only a single antenna is powered on at a time
.
The reader was configured to
antenna

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5


dense
reader M = 4 high speed mode, dual target search, and

a

tags in view estimate of
40
0.

The
standard packed pantry CTB was
carried through the habitat, entering at portal
1
and exiting
through the opposite door. The CTB was carried through the habitat in t
hree positions: held by
both hands in the front, carried by a handle using the right hand, and carried by a handle using
the left hand.

Figure
4

shows the orientati
on of the CTB as it was carried through the portal
door.
Two scenarios were tested:

(i)
reader was triggered using the pressure sensing mat

on the
landing
,

and
(ii)
reader continuously on to read items. In the latter case, the CTB
wa
s placed in
the high

bay directly in front of the habitat portal
at a distance of
about 40 feet away, in a
position out of view of the
reader

antennas
. The reader

wa
s started and then the CTB
was

moved
in
to

view and carried through the habitat.



Figure
4
. Left picture shows the orientation of the CTB as viewed from inside the portal door as the CTB was
carried in front into the habitat. The right picture shows

the orientation of the CTB as viewed from inside
the portal when the CTB was carried by

the right and left hands into the habitat.


For each combination of three carry positions and two trigger scenarios, the test was performed
five times.
Following
the test with the standard packing CTB, two random packing tests were
performed. The random packing was accomplished by removing every item
from the CTB. T
he
t
est personnel randomly grab
bed

a handful of
items
-
at
-
a
-
time
and place
d

them
back
into the
CTB.

A
sequential
pictorial record of the random packing

configurations

1 and 2 are shown in
Appendixes

C and D. Thirty RFID test walkthroughs were performed for each of the two
random packing

configurations

in the same manner as the walkthroughs for the stan
dard packing.

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6


6

Portal results

The overall average of the ninety
trials

show
s

that at the item level, the read success (tag read/
52
total tags) is 75
.5
%. The overall average
at

the
Ziplock
level
of 17 tags
is 9
4.
5%. There is little
difference in read succe
ss between the carrying methods
.

Similarly, the use of the mat to trigger
the
reading
versus continuous reader operation has insignificant effects on the read success of the
tags as they pass through the portal.


Table 1. Effects of CTB Carrying Method
.


average front

average right

average left

item level

75.5%

75.3%

75.7%

ziplock level

95.1%

94.7%

93.7%



Table 2. Effects of Trigger Mechanism.


average mat

trigger

average cont ON

item level

76%

75%

ziplock level

95%

94%



Table
3
shows the effects of packing on the read success.
As expected, the read success is
dependent on the arrangement and orientation of the items inside the CTB

as is shown by the
packing arrangements
. The blocking and tuning effects of adjacent items would a
ffect the
readability of the RFID tags.


Table
3
. Packing Effects on Read Success.


standard packing

r
and
om packing

1

r
and
om packing

2

item level

72%

81%

74%

ziplock level

95%

98%

91%


7

C
onclusion

One RFID portal was tested at the
Wireless

Habitat Test Bed using a pantry CTB with 52 total
tags. The read rate
at the item level

averages 75.5%
,

while the read rate at the
Ziplock
bag level
is 94.5%. The carry method and
trigger
mechanism

are insignificant in terms of read success.
The varying results based on packing order confirm that the
read success is dependent on the
arrangement and orientation of the items inside the CTB.
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A
-
1


Appendix A.

Items inside the pantry CTB
. The ite
m in red font is the CTB level tag. Items in
blue font are the tags on the ziplock bags. Items in black font are the item level tags.

Item

Tag Model

Name

1

2x2

Supply Pantry CTB

2

Squiggle

Kapton Tape, 1” Bag (1)

3

Squiggle

Kapton Tape, 1”

4

Squiggle

Crewmember, Microcassette, Tape Bag (4)

5

Squiggle

Battery, AA Alkaline (Battery, Size AA, 1.5V) (10)

6

2x2

Cartridge, Ink, Epson Bag (2)

7

2x2

Cartridge, Ink, Tri
-
color, Epson

8

2x2

Cartridge, Ink, Tri
-
color, Epson

9

Squiggle

Hand Cream,
Aloe Gel Bag (4)

10

2x2

Hand Cream, Aloe Gel (0.75 oz)

11

2x2

Hand Cream, Aloe Gel (0.75 oz)

12

2x2

Hand Cream, Aloe Gel (0.75 oz)

13

2x2

Hand Cream, Aloe Gel (0.75 oz)

14

Squiggle

Shave Cream, Edge Gel Bag (4)

15

2x2

Shave Cream, Edge Gel

16

2x2

Shave Cream, Edge Gel

17

2x2

Shave Cream, Edge Gel

18

2x2

Shave Cream, Edge Gel

19

Squiggle

Deodorant Bag (3)

20

2x2

Deodorant, Shure

21

2x2

Deodorant, Shure

22

2x2

Deodorant, Shure

23

Squiggle

Toothbrush Bag (5)

24

Squiggle

Toothbrush, Oral B
-
40
(Medium)

25

Squiggle

Toothbrush, Oral B
-
40 (Medium)

26

Squiggle

Toothbrush, Oral B
-
40 (Medium)

27

Squiggle

Toothbrush, Oral B
-
40 (Medium)

28

Squiggle

Toothbrush, Oral B
-
40 (Medium)

29

Squiggle

Toothpaste Bag (2)

30

TM4

Toothpaste, Crest

31

TM4

Toothpaste, Crest

32

2x2

Floss, Dental, Glide (Floss, Glide) bag (3)

33

2x2

Hygiene, Towel, Lintless Bag (2)

34

Squiggle

Hygiene, Towel, Lintless

35

Squiggle

Hygiene, Towel, Lintless

36

Squiggle

Hygiene, Towel, Washcloth Bag (2)

37

2x2

Huggies Wipes
Assembly (2)

38

Squiggle

Huggies Wipes Assembly

39

Squiggle

Huggies Wipes Assembly

40

Squiggle

No Rinse Body Bath Pouch Bag (4)

41

dog
-
earred squiggle

No Rinse Body Bath Pouch (No Rinse Body Bath)

42

Max

No Rinse Body Bath Pouch (No Rinse Body Bath)

43

Metalcraft squiggle over foam

No Rinse Body Bath Pouch (No Rinse Body Bath)

44

TM4

No Rinse Body Bath Pouch (No Rinse Body Bath)

45

2x2

Tape, Shurtape, 2” Bag (1)

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A
-
2


46

2x2

Tape, Shurtape, 2”

47

2x2

No Rinse Body Bath (4)

48

TM4

No Rinse Body Bath

49

Flex

No Rinse Body Bath

50

Flex

No Rinse Body Bath

51

Prox

No Rinse Body Bath

52

Squiggle

Latex Gloves

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B
-
1


Appendix B. The packing of the standard pantry CTB


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B
-
2




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B
-
3



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C
-
1


Appendix C. Random packing 1


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C
-
2




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C
-
3



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D
-
1


Appendix D. Random packing 2


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D
-
2




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D
-
3