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.