Detection of Patient Falls Using Three-Axis Accelerometer
Detection of Patient Falls Using Three-Axis Accelerometer
Umer JamshaidTyler Quarles
Parampal RandhawaMartha Serna
Matthew Treinish
March 15, 2011
School of Electrical and Computer Engineering
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Project MotivationProject Motivation
• Broken Hipsters Monitoring System (BHMS) – What: Creation of automated fall detection system– Why: Large number of fall related injuries– Who: Residents at Assisted Living Centers– Cost: $59 per unit
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GoalsGoals
• Creation of Fall Detector• Small enough to wear • Low cost• Low power• Detects different falls
• Development of Control Box • Detect resident in bed with pressure sensors• Send alert signal to caretaker’s station
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CompetitionCompetition
• Push-to-Call emergency pendant available online• Some problems:
– Requires patients to remember they are wearing a pendant
– Does not alarm staff unless button is pressed• Patient alertness questionable• High cost ($99.95 + $24.95/month)
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Previous Senior Design WorkPrevious Senior Design Work
• Use of semi-active RFID tag on patient, coupled with Antenna and Activator on floor– 1 foot detection range from floor– Small area covered by Antenna– 1 Watt Activator power
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BHMS Design OverviewBHMS Design Overview
PIC18 Microprocessor
Pressure Pad
Red LED
Three-Axis Accelerometer
Xbee Module
PIC18 Microprocessor
Orientation Data
Xbee Module
Fall DetectorControl
Box Wireless Communication
Pressure Data
Alert Signal
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Fall Detector Placement IssueFall Detector Placement Issue
• Original design proposal for belt-mounted Fall Detector– Able to detect hip orientation– Easily mounted on belt– Unobtrusive location
• Fall Detector mounted on an elastic band on leg is a better position:– Easier to detect orientation of patient – Patient injury less likely
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Modifying Fall Detection AlgorithmModifying Fall Detection Algorithm
• Fall Detector microprocessor determines if fall has occurred
• Problem: fall detection algorithm based on orientation may be unable to detect specific types of falls
• Alternative: detect falls using patient acceleration– Speed of fall does not affect accuracy
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System Expandability System Expandability
• Need to account for chairs and toilet seat in resident’s room to avoid false positives
• BHMS easily expandable due to modular design
• Pressure strips can be added to the system at minimal additional cost
• ZigBee protocol can accommodate multiple wireless modules as a single network
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Potential Room LayoutPotential Room Layout
Resident with Fall Detector Control Box
Pressure stripPressure strip
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Fall Detection AlgorithmFall Detection Algorithm
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Project ScheduleProject Schedule
• (03/01) - Design schematics for Fall Detector & Control Box
• (03/11) - Build prototypes• (03/18) - Test & program microcontrollers• (04/15) - Optimize Fall Detector algorithm• (04/29) - Final project presentation
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Cost of MaterialsCost of Materials
Materials Price
Triple Axis Accelerometer $ 14.95
Microcontrollers $ 12.20
XBee Wireless Modules $ 84.00
Computer and Monitor $ 500.00
Wires/Cables $ 8.00
Software Development environment $ 690.00
Miscellaneous materials $ 8.88
TOTAL COST $ 1,318.03
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Labor Cost AnalysisLabor Cost Analysis
TASKS TOTAL HOURS
SALARY PER HOUR
TOTAL COST PER TASK
Lecture/Group meetings
90 $30.00 $2,700.00
Research 90 $30.00 $2,700.00
Equipment Setup 30 $30.00 $900.00
Software Programming
180 $30.00 $5,400.00
Debugging 100 $30.00 $3,000.00
Product Testing 100 $30.00 $3,000.00
Demos/Preparation 40 $30.00 $1,200.00
TOTAL HOURS 630 TOTAL LABOR $18,900.00
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Total Cost Analysis Total Cost Analysis
• Cost of Materials: $1,318.03
• Cost of Labor: $18,900.00– Cost of labor is based on 5 entry level engineers
• Prototyping first product will be expensive
• Mass production will lower the cost of product. – Final cost after 1000 units sold: $ 59.00
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Potential Future Work Potential Future Work
• Commercializing BHMS
• Implement touch screen GUI at caretaker station
• Add remote access to caretaker station
• Target hospital and domestic markets
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QuestionsQuestions
One in three people over 65 fall each year, and more than 300,000 hip fractures occur each year because of falls.