Detection of Patient Falls Using Three-Axis Accelerometer
16
Detection of Patient Falls Using Three- Axis Accelerometer Umer Jamshaid Tyler Quarles Parampal Randhawa Martha Serna Matthew Treinish April 26, 2011 School of Electrical and Computer Engineering
description
Detection of Patient Falls Using Three-Axis Accelerometer. Umer Jamshaid Tyler Quarles Parampal Randhawa Martha Serna Matthew Treinish. April 26, 2011. School of Electrical and Computer Engineering. Project Motivation. - PowerPoint PPT Presentation
Transcript of Detection of Patient Falls Using Three-Axis Accelerometer
Detection of Patient Falls Using Three-Axis Accelerometer
Detection of Patient Falls Using Three-Axis Accelerometer
Umer JamshaidTyler Quarles
Parampal RandhawaMartha Serna
Matthew Treinish
April 26, 2011
School of Electrical and Computer Engineering
2
• One in three people over 65 fall each year, and more than 300,000 hip fractures occur each year because of falls*
• Broken Hipsters Monitoring System (BHMS) o What: Creation of automated fall detection systemo Why: Large number of fall related injurieso Who: Residents at Assisted Living Centerso Cost: $59 per unit
Project MotivationProject Motivation
1
3
Design Goals: Proposed vs AchievedDesign Goals: Proposed vs Achieved
• Fall Detector Small enough to wear Low cost Low power Detects different falls
• Control Box Detect resident in bed
with pressure sensors Send alert signal to
caretaker’s station
• Fall Detector Prototype designed that can be
scaled down Cost at $59 Low power: 40mA, enough for
5.6 hours of continuous use Detects orientation vs
accelerationControl Box Correctly detect resident in bed
with pressure pad Send alert signal to caretaker’s
station
2
4
BHMS Design OverviewBHMS Design Overview
PIC18 Microprocessor
Pressure Pad
Red LED
Three-Axis Accelerometer
Xbee Module
PIC18 Microprocessor
Orientation Data
Xbee Module
Fall DetectorControl
BoxWireless
Communication
Pressure Data
Alert Signal
3
5
Fall Detector – PCB & ProtoboardFall Detector – PCB & Protoboard
4
6
Control Box – Protoboard EnclosureControl Box – Protoboard Enclosure
5
7
Fall Detector Design DetailsFall Detector Design Details
• Analog three-axis accelerometer– Only used readings from one axis
• Threshold angle 35 degrees from horizontal– Detects falls in all directions (including inverted!)
• Detection loop runs for 18 seconds
• XBees communicate in Transparent Mode
• Protoboard runs off 3.3 V power supply– PCB designed to run off 3 V coin cell battery
6
8
Control Box Design DetailsControl Box Design Details
• Pressure pad used with ADC to prevent false positives
• LED lights up to represent Alert Signal
• Clear button to reset Fall Detector algorithm
• Control Box plugs into power socket– Voltage regulator on board converts to 3.3 V
7
9
BHMS Design TestingBHMS Design Testing
• Used XBee Explorer with X-CTU to monitor and simulate wireless communication
• Tested possible fall scenarios with programmed Fall Detector and Control Box
• Used acknowledge signals from Control Box to ensure reliable communication
• Tested Fall Detector range in lab (10 m)• XBees rated to 30 m indoors
8
10
Room LayoutRoom Layout
Resident with Fall Detector Control Box
Pressure stripPressure strip
9
11
Fall Detection AlgorithmFall Detection Algorithm
10
12
Design IssuesDesign Issues
• Switched to analog accelerometer• XBee reset
– Unable to control, disconnected• XBee configuration• Clear button
– Required to press multiple times• Accelerometer data
– Peaks when flat– Fixed by adding high and low threshold values
11
13
BHMS Design SpecificationsBHMS Design Specifications
• Detect different types of falls, within 30 s (Y)• Pressure sensor on bed filters out false positives
• Small size, lightweight (Y)• Fall Detector able to fit onto 2.5 in2 PCB
• Range of 20 m• Tested to 10 m
• Battery life of 1 month (N)• Current code only lasts 5 hours on 3 V coin cell• Sleep mode for XBees can improve battery life
12
14
Final Budget Analysis Final Budget Analysis
• Cost of Materials: $1,318.03
• Cost of Labor: $18,900.00o Cost of labor is based on 5 entry level engineers
• Prototyping first product will be expensiveo Total cost: $ 20,218.03
• Mass production will lower the cost of product. o Final cost after 1000 units sold: $ 59.00
13
15
Potential Future Work Potential Future Work
• Add touch screen GUI at caretaker station• Decrease battery consumption by sleeping the XBees
when not in used• Implementing a multi-room solution using the
networking features of the XBees• Include sitting falls in detection algorithm• Expand BHMS using modular design
14
16
Questions?Questions?
15
