design of a wheelchair-mounted transfer assist device
DESCRIPTION
University of Pittsburgh Senior Design – BioE 1160/1161. Design of a Wheelchair-Mounted Transfer Assist Device. Michael Anderson Andrew Feola Jill Marion Bryan Shelly April 18, 2006 Mentors: Alicia Koontz, PhD, RET Jeremy Puhlman, BSE. Background. Wheelchair Patients - PowerPoint PPT PresentationTRANSCRIPT
Design of a Wheelchair-Mounted Transfer Assist Device
University of PittsburghSenior Design – BioE 1160/1161
Michael AndersonAndrew Feola
Jill MarionBryan Shelly
April 18, 2006
Mentors: Alicia Koontz, PhD, RET Jeremy Puhlman, BSE
• Wheelchair Patients
• Have trouble transferring from chair
• Bed, toilet, sofa, etc.
• Must carry bulky transfer boards, benches
Background
Current Solutions
•Transfer boards, benches•Wall and ceiling-mounted devices
•Portability Issues!
•Our goal•To design a modified wheelchair armrest such that a transfer assist device is contained within the armrest
Market Analysis- Frost and Sullivan
• North American Mobility Aids Market• Manual Wheelchairs
• 313,000 units in 2001(standard)• 77,000 units in 2001 (lightweight)• 313,000 units + 77,000 units = 390,000
units * $60 /unit=
$23,400,000 market for our product to be used on manual wheelchairs
Frost and Sullivan, 2001
• Lightweight manual wheelchairs• $102 million/ 77,000 units in 2001
• $130 million in 2008• Sunrise Medical Quickie II 30% of market
• 0.3 * 77,000 = 23,100 units
23,100 units * $60/unit = $1,386,000
$1,386,000 market for our product to be used on the Quickie II model
Market Analysis- Frost and Sullivan
Frost and Sullivan, 2001
• Home Healthcare Market (US)
• $2.03 billion-devices in homecare (2001)
• $1.23 billion- home durable medical equipment (1999)
Market Analysis- Frost and Sullivan
Frost and Sullivan, 1999, 2001
• Growth rate of home healthcare market- 14% due to:• Increasing number of elderly (baby
boomers)• Medicare moving toward covering at
home treatments/devices more than in hospital
• Improvements in technology• Allows greater number of medical
procedures/monitoring to be done at home
Frost and Sullivan, 2001
Market Analysis- Frost and Sullivan
Design Requirements
•Armrest converts into a transfer board
•Fit in space occupied by standard armrest
•Weight < 10 pounds
•Provides same comfort as standard armrest
•Able to support up to 250 pounds
Original Design
Final Design
Our Prototype
Our Prototype
Prototype Fabrication
•Human Engineering Research Laboratory
•Wire EDM
•Aluminum 6061 Alloy (prototype)
•Mass Production
•Plastic Injection Molding
•High-density polyethylene
Finite Element Analysis
Maximum displacement = .006 inches
Minimum factor of safety = 3.2
Experimental Methods
• Validate FEA results
• Protocol – both ends supported
• Digitize a point (no load applied)
• Apply load
• Digitize same point (with load applied)
• Compute displacement
Experimental Testing
Experimental Results
FEA test Exp. test
.0007 .0011
.0024 .0097
.0015 .0031
**All units are inches
High-density Polyethylene
Maximum displacement = .37 inches
Minimum factor of safety = 1.4
Standard Transfer Board
Maximum displacement = 0.4 inches
Minimum factor of safety = 1.1
Survey Results
•Eight (8) volunteers
•7 use transfer boards
•3.9 / 5 difficulty rating of current boards
•4.75 / 5 aesthetic rating of our product
•All 7 would prefer a transfer board that does not need to be carried
Competitive AnalysisTransfer bench
• Invacare transfer bench• $120
• Carex transfer bench• $300
Standard transfer board• Allegro Medical wooden board
• ~ $37 per unit
• Therafin Theraslide transfer board• $100 per unit
Our device• Plastic Injection Molding
• $50-60
Competitive Analysis
Strengths
• Price• Comparable to current transfer boards
• Portability
• Minimal additional weight
Weaknesses
• Limited armrest adjustability
• One sliding mechanism
Constraints—Testing Human factors
• Lack of human subject testing• Falls, etc.
Production• Material availability
• Testing done on aluminum, not plastic
Economic• Cost of prototyping
• Only one prototype
Manufacturability Considerations
• Simple Design
• Ease of injection molding
• Standard shapes
• Lack of small, irregular pieces
• Ease of mass production
Human Factors Considerations• Standard transfer material
• Patient can slide easily across board
• Cushioning consistent with standard armrests
• Handles in transfer board
• No sharp edges
FDA Regulation
• CDRH website
• Sec. 890.3910 Wheelchair accessories
• Includes armrests, transfer boards
• Class I device
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPCD/classification.cfm
Individual Project Work
• Jill Marion• Contact companies and
patients
• Market Analysis
• Prototype testing
• DHF, SBIR
• Mike Anderson• SolidWorks design
• Prototype testing
• COSMOSWorks analysis
• DHF, SBIR
• Andrew Feola• SolidWorks design
• COSMOSWorks analysis
• Prototype testing
• DHF, SBIR
• Bryan Shelly• Material selection
• DHF, SBIR
• Manufacturing
Project Timeline
Future Considerations
• Human subject testing
• Additional sliding mechanism
• Armrest height adjustability
AcknowledgementsAlicia Koontz, PhD, RET
Jeremy Puhlman, BSE
Alexis Wickwire, BS
Human Engineering Research Labs
Pittsburgh Life Sciences Greenhouse
University of Pittsburgh BioE Dept.
A generous gift from Dr. Hal Wrigley and Dr. Linda Baker
Thank You
• Questions?