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STATag
Prototype Presentation
Daniel Tubbs
Jason Sadler
Chad Hilton
December 13, 2004
Brian Easton
Latricia Simon
James Mayor
1
Societal Problem Defined
 Hospital staff waste time locating mobile
equipment, wasting billions of dollars
annually.
 35-60%1 of a nurse’s time is wasted on



Searching for equipment
Clarifying orders
Entering redundant information
 Wasting $58 - $99 billion annually2
December 13, 2004
2
Solution
The use of STATags will
 Reduce man hours searching for needed equipment
 Increase staff efficiency
 Increase a nurse’s efficiency at least 10%1
 Lower operating costs
 Save a real $1 for every $4 of efficiency gained3
(reduction of overtime, increased turnaround)
 Increase job satisfaction3
December 13, 2004
3
STATag Goals
 Use dead-reckoning to determine current
location
 Use network security
 Use a self-discovering and self-configuring
network
 Handle large quantities of equipment
December 13, 2004
4
STATag Goals (continued)
 Activate alarms
 Store historical location and usage data
 Run without intervention for long periods


Battery must last 5-7 years
Need calibration only when battery is changed
December 13, 2004
5
STATag Limitations
STATag will not:
 Prevent theft
 Collect or transmit personally identifiable
health information (covered under HIPAA)
 Communicate further than 100 feet between
STATags
December 13, 2004
6
STATag System
`
STATag
Web Browser
User
STATag
STATag
Network Coordinator
DB Server
Internal Webserver
STATag
STATag
Database
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Web Server / User Interface
`
STATag
Web Browser
User
STATag
STATag
Network Coordinator
DB Server
Internal Webserver
STATag
STATag
Database
December 13, 2004
8
Database
`
STATag
Web Browser
User
STATag
STATag
Network Coordinator
DB Server
Internal Webserver
STATag
STATag
Database
December 13, 2004
9
STATags
`
STATag
Web Browser
User
STATag
STATag
Network Coordinator
DB Server
Internal Webserver
STATag
STATag
Database
December 13, 2004
10
Web Server
 Open source web server



Provides a bridge between the end user and
the database
Eliminates the need for client software
Allows any client with a web browser to
connect



December 13, 2004
PC
Laptop
PDA
11
Database
 Open source relational database collects and
stores STATag location information





Real-time look-ups
History
Alarms
Inventory
Reports
December 13, 2004
12
STATag Diagram
Battery
December 13, 2004
802.15.4 Module
Usage Module
(In use switch)
Microcontoller
Movement
Detection Module
(Accelerometers &
Gyroscopes)
Flash RAM (1MB)
Tamper Detection
Module
(Tag Removed
Switch)
13
STATag
 Accelerometers and gyroscopes detect
orientation and motion
 Microcontroller calculates current position
 802.15.4 module communicates to DB server
via mesh network
 Switches provide state information
 RAM records position data when unable to
communicate with DB server
 Battery keeps everything running for 5 years
December 13, 2004
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Project Risks – Web Interface
 Inadequate response time
 Complexity of use
 Complexity of administration
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Project Risks - Database
 Database size may grow too fast
 Database design may be too complicated to
use without regular administration
 Response time may be inadequate for a large
number of tags
December 13, 2004
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Project Risks – STATag
 Interference with hospital monitoring equipment
 STATag transmits 1% the power of other safe wireless
devices
 Most major hospitals are implementing WiFi
 Conflicts with other 2.4 GHz networks
 802.15.4 has been designed for interoperability
 802.15.4 and ZigBee are new standards and
therefore there may be unknown issues


Hardware issues are being resolved by manufactures
Software issues will be correctable by patching
December 13, 2004
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Prototype Goals
 Build a prototype for each subsystem
 Demonstrate integration of the subsystems



Web server and user interface
Database
Individual STATag
December 13, 2004
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Prototype Diagram
`
Web Browser
User
Dead Reckoning Module
8
N
11
02 .
etw
ork
DB Server
Internal Webserver
Simulated Position Data
Laptop
Live Position Data
Database
December 13, 2004
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Prototype vs. Real System
Database
Web Server
User Interface
Web Browser
Hardware
December 13, 2004
Prototype
MSSQL
IIS 5.1
ASP.NET
Any
Same PC
Real System
MySQL
Apache
Java
Any
Separate
Servers
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Prototype vs. Real System
Accelerometer
Microcontroller
Wireless Network
RAM
Gyroscope
In-use Switch
Tag-removed Switch
December 13, 2004
Prototype
2-axis
Laptop
802.11b
Log File
No
No
No
Real System
3-axis
On-board
802.15.4
On-board
3-axis
Yes
Yes
21
Database Accomplishments
 Each STATag history entry requires 40 bytes

Average hospital database size – 67.2 GB
(1 year history of 1368 tags updated every 30
seconds)
 Database design is simple
December 13, 2004
22
Database Schema
sn_type
description
PK
type_num
PK
serial_num
description
FK1
type_num
region
PK,FK1
PK,FK1
north
south
east
west
top
bottom
history
PK
PK,FK1
timestamp
statag_id
pos_x
pos_y
pos_z
in_use
December 13, 2004
region_id
statag_id
id_sn
PK
statag_id
FK2
serial_num
removed
statag_region
PK
PK,FK1
region_id
statag_id
active
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User Interface / Database Demo
December 13, 2004
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STATag Prototype
 ADXL202EB-232 2-axis accelerometer
evaluation board with serial interface
 Custom application calculates position data
from log file created by ADXL202EB-232
 Position data sent to database server via
802.11b network
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ADXL202EB-232
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ADXL202 Surface Mount Package
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STATag Demo
 Acceleration (a)

Measured by accelerometer
 Speed (s)

sfinal= sinitial + a * time
 Position (p)

pfinal= pinitial + s * time
December 13, 2004
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Issues Encountered
 Minimum error - 0.0002 g
 5-year cumulative error – minimum of 95
miles per axis
 Location uncertainty


Prototype - 9,025 square-miles
Production - 860,000 cubic-miles
 Maximum allowed error - 1.91 x 10-9 g
(5 ft. error after 5 years)
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Position Uncertainty After 5 Years
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Five-year Error vs. Max. Error
Cumulative Error (ft)
1000000
100000
10000
504,922
252,461
126,230
63,115
31,558
15,779
7,889
3,945
1,972
1000
986
493
247
123
100
62
31
15
10
8
4
1
09
E53
1. -09
E
05
3. -09
E
10
6. -08
E
22
1. -08
E
44
2. -08
E
88
4. -08
E
77
9. -07
E
95
1. -07
E
91
3. -07
E
81
7. -06
E
56
1. -06
E
13
3. -06
E
25
6. -05
E
25
1. -05
E
50
2. -05
E
00
5. -04
E
00
1. -04
E
00
2.
Maximum Allowed Error (g)
December 13, 2004
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Detected Acceleration by Angle
100
90
Detected Acceleration (%)
80
70
60
50
40
30
20
10
0
88
84
80
76
72
68
64
60
56
52
48
44
40
36
32
28
24
20
16
12
8
4
0
Degrees
December 13, 2004
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Final Prototype Diagram
`
Web Browser
User
Dead Reckoning Module
DB Server
Laptop
Internal Webserver
Simulated Position Data
Database
December 13, 2004
33
Options
 Continue working with Analog Devices to find
an accelerometer / software combination that
meets our design needs
 Replace the dead-reckoning functionality with
Real-Time Locating Systems (RTLS)
components
 Both options affect only the STATag
subsystem and remaining subsystems remain
the same
December 13, 2004
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Continue with Dead-Reckoning
 PRO


Costs and profits are well understood
Progress already being made
 CON


May not be able to solve issues
May require additional manpower or funding
December 13, 2004
35
Switch to RTLS
 PRO



Commercial off the shelf product
Standardized, multiple vendors
Not affected by cumulative error
 CON



Higher wireless transmitting power
Increased hospital installation cost
Delayed hospital ROI
December 13, 2004
36
Recommendations
 Move forward with database, web server, and
user interface development
 Convert STATag to use RTLS components
December 13, 2004
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Questions?
December 13, 2004
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References & Calculations
1 Cindy Jimmerson, April 7, 2004
2 $166 Billion (Nurse’s Salary and Benefits)4 x
35% = $58 Billion
$166 Billion (Nurse’s Salary and Benefits)4 x
60% = $99 Billion
3 Murphy, Mark: Eliminating Wasteful Work in
Hospitals Improves Margin, Quality, and
Culture
December 13, 2004
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References & Calculations
4 975,9625 Beds x 10 Mobile Medical Devices
per bed = 9.76 Million Mobile Medical
Devices
5 Hospital Statistics, 2004 edition, American
Hospital Association, as reported by the
American Hospital Association website
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