Presented at GDG Singapore DevFest 2013 on 12/10/2013, by Lim Seow Chiong, Senior Lecturer/Info-Communications Technology, School of Electronics & Info-Comm Technology, ITE College Central, Singapore. With the mobile revolution, smartphone applications are being developed to provide functions previously found only in dedicated electronic devices. In this talk, the speaker will explore using the Android smartphone as an emergency alert system with fall detection capability. Comparison will be made between a dedicated medical alert system and the smartphone-based solution. The speaker will also address the technical challenges and limitation of using Android smartphone for fall detection.

1. Android Emergency Alert
with Fall Detection
GDG DevFest
Singapore
12 October 2013
Lim Seow Chiong
Senior Lecturer
ITE College Central
lim_seow_chiong@ite.edu.sg

2. Agenda
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Why Fall Detection?
Dedicated Fall Detection Systems
Smartphone‐based Fall Detection
Android Personal Emergency Alert System
– Design, Features, Fall detection method,
Implementation highlights.
• Smartphone App Advantages & Challenges
• Conclusion
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3. 1 in 3 Elderly suffers from falls each year
Rapid response & aid after fall is important
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4. Fall Detection Systems
• Require effective, reliable fall detection
principle & algorithm
• Wearable systems
– Monitoring body motion with body‐
worn devices with sensors like
accelerometer and/or gyroscopes.
– Pattern matching/threshold‐based
method.
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5. Wearable Medical Alert Systems
• Two components:
– Console (base station) connected to phone line or
Internet.
– Wireless neck/wrist pendant with fall sensor.
• Panic/SOS button
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6. Medical Alert Systems
• Requires application‐specific hardware &
software
• Installations required
• Limited range (indoor)
• Subscription to 24‐hr help/monitoring centre
• Cost
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Source: http://www.activemedical.com.sg

7. Smartphone as Fall Detection Device?
• Need for a pervasive, reliable, adaptable,
effective and cheap solution.
• Smartphone is ubiquitous
– Communication capabilities
• Phone call, SMS
– Integrated sensor hardware:
• Motion sensors: accelerometer, gravity sensor,
gyroscope
• Position sensors: orientation sensor and magnetometer
– Android smartphones are now more affordable.
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8. Smartphone as Fall Detection Device?
• Proliferation of Smartphone apps that provides similar
functionality to dedicated hardware devices.
– Eg apps that provide GPS & location‐based solutions.
• Convergence of electronic devices into smartphone
platform.
• Smartphone apps are appealing:
– All‐in‐one convenience – do everything with the
smartphone.
– Cheaper.
– Easy to download/purchase.
– Familiar touch screen interface.
– Can be used both indoors & outdoors.
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9. Smartphone as Fall Detection Device?
• Smartphone‐based fall detection systems:
– iFall
– PerFallD
– Smart Fall
Detection
– uFall
– CRADAR
• Detection method: Falls are characterized by
sudden acceleration change.
• Experimental, proof of concept – solutions are
not comprehensive.
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10. Personal Emergency Alert System
• Project Objectives:
– Create a smartphone‐based comprehensive
emergency alert system, with fall detection
capability, comparable to a dedicated device.
– To be a low‐cost alternative to dedicated medical
alert systems for the needy, elderly & people with
disabilities.
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11. Smartphone Requirements
• Embedded triaxial accelerometer.
• Can be comfortably carried or worn using an
elastic waistband or armband – smaller form
factor.
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12. Features
• Fall detection as well as manual alert (panic button).
• Use accelerometer with adjustable fall detection
sensitivity:
– Android phones are not uniform:
• Different versions
• Different device manufacturers
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User can cancel alert in the event of false positive.
Works even when phone is on standby (power efficiency).
Calls & message (SMS) up to 5 caregivers each.
Caregivers contacts taken from phone’s contact list.
Speakerphone on with maximum volume for phone call.
Uses GPS for location reporting (through SMS).

13. What is Fall?
• A fall is a sudden change of body position
(from a height) coming to rest on the ground
(after a hard impact), followed by a moment
of inactivity (subject becomes unconscious).
• Focus is on a serious fall – subject is immobile
& unable to get help.
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14. Acceleration Pattern of a Fall
• Resultant/Total Acceleration:
G=9.81m/s2
• Acceleration pattern of a fall:
– Initial position (1G if subject is at rest)
– Sudden change to free fall (0G)
(Lower Threshold)
– Impact on the ground (sudden surge in
acceleration, can be > 3G) (Upper Threshold)
– Inactivity (1G)
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15. Personal Emergency Alert System
A Low‐Cost
Medical Emergency Alert System
with Fall Detection
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16. • Panic button
• Caregivers’ list
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17. • Wakes up from standby
• Home screen/Key guard
cleared
• Inactivity timer
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18. • Audio warning message
• Cancel Alert button
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19. • Sends SMS message
to caregiver(s)
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20. • Calls caregivers one by
one
• Speakerphone on with
maximum volume
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23. Caregiver’s Phone
• Receives SMS message with
location information
(latitude, longitude &
location name).
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24. Customized SMS Client (Caregiver)
SMS Notification
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PEAS SMS Messages
Google Map of Location

25. Customized SMS Client
• Context menu to view and delete messages
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26. Other Features
• User can customize our app with Shared
Preferences.
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27. Shared Preferences
Customizable Options:
1. Fall detection sensitivity
2. Sensitivity when on standby
3. Inactivity period
4. User name
5. “Help Me” button ON/OFF
6. Time to cancel false alert.
7. Audio alert ON/OFF
8. Vibration alert ON/OFF
9. Send SMS ON/OFF
10.SMS message contents
11.GPS location ON/OFF
12.Voice Call ON/OFF
13.Add/Remove caregivers
through phone contact list.

28. Other Features
• Code implemented as a library in
Eclipse.
– Allows for code sharing between
different variants of the same app, eg
app with or without fall detection.
Library: package="ite.cc.peas“
Medical Alert: package="ite.cc.peas.medicalalert”
Safety Alert : package="ite.cc.peas.safetyalert”
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29. Android Application Components
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Activities
Application object
Context and Options Menu
Content Providers
Hardware sensor
(accelerometer)
Intents & Broadcast Receivers
Location‐Based Services
Media Player
Notification
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Power Management
Service
Shared Preferences
Simple Animations
Telephony & SMS

30. App Advantages
Positive Impact
Cheap Alternative ( Android 2.1)
Android is Cool & Trendy
Potential for Widespread Adoption
Established Distribution Channels
Configurable
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31. Challenges
• Fall detection technology is still being
perfected.
– False positives : addressed with inactivity period &
cancel timer.
• Lifestyle change required for users
– Users carry their phones differently.
– What about night time? In the shower (not
waterproof)?
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32. Challenges
• Incoming calls with vibration mode may
trigger alert
– Can’t control user ‘s vibration strength setting.
– Fall detection is turned off when there is incoming
call.
• User may be overwhelmed with the number
of customizations.
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33. Limitation
• Smartphone accelerometer is not optimized
for continuous sensing
– Reduced sampling rate when phone is on standby
for some models.
– Certain models accelerometer becomes inactive.
Smartphone
Normal Sampling Rate
Standby Sampling Rate
Galaxy S II (Android 2.3.6)
Every 5ms
Every 5ms
Galaxy S III (Android 4.1.2)
Every 10ms
Every 10ms
Nexus 7 (Android 4.3)
Every 10ms
Every 10ms
Galaxy Ace (Android 2.3.6)
Every 15ms
No data
Lenovo A820 (Android 4.1.2)
Every 10ms
Every 500ms
UMI X1S (Android 4.2.1)
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Every 20ms
Every 500ms

34. Smartphone App vs Dedicated Device
• Dedicated device can provide:
– Better user experience
– Better accuracy, quality & robustness
– More ideal form factor (size & weight)
– Better battery life
• Each targets different consumer segment
– App offers lower price & convenient access
– App can exploit other alert methods, eg e‐mail,
Twitter, Google Cloud Messaging.
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35. Conclusion
• Smartphone‐based emergency alert solution:
– Low‐cost alternative for people who cannot afford
dedicated medical alert solution.
– Very effective if emergency is correctly triggered.
– Solution for both indoor & outdoor.
– But choice of smartphone is important.
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36. References
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2007, WHO Global Report on Falls Prevention in Older Age, Available from:
http://www.who.int/ageing/publications/Falls_prevention7March.pdf.
Frank Sposaro, Gary TysoniFall, 2009, iFall: An Android application for fall
monitoring and response, Annual International Conference of the IEEE Engineering
in Medicine and Biology Society.
Qiang Li,John Stankovic, Mar Hanson, Adam Barth, 2009, Accurate, Fast Fall
Detection Using Gyroscopes and Accelerometer‐Derived Posture Information, Sixth
International Workshop on Wearable and Implantable Body Sensor Networks.
Jiangpeng Dai, Xiaole Bai, Zhimin Yang, Zhaohui Shen, & Dong Xuan, 2010,
“PerFallD: A pervasive fall detection system using mobile phones”, 8th IEEE
International Conference on Pervasive Computing and Communications
Ian James Daniel Gonzales, 2011, Fall Detection Using a Smartphone, Gjøvik
University College.
Abalta Technologies, 2011, White Paper: Dedicated Devices Aren’t Dead, Available
from: http://abaltatech.com/images/uploads/ABALTA_Dedicated_Devices_‐
_White_Paper_FINAL_052611.pdf.