Post on 22-Feb-2016
description
Leg Ergometer for Blood Flow Studies
Amy Weaver, Cali Roen, Lacey Halfen, Hyungjin Kim
BME 201March 9, 2007
Client: William SchrageDept. of Kinesiology
Advisor: Paul ThompsonDept. of Biological Systems
Engineering
Overview
Problem statement Background Design requirements Design alternatives Proposed Design Future work
Problem Statement
Test subject will use the ergometer to maintain a constant kicking motion
Leg must passively return to original position Femoral artery is imaged using an ultrasound Used to determine blood flow to the leg
during exercise
Background: Blood Flow Research
Measure blood flow in femoral artery Examine how smaller blood vessels regulate
upstream (femoral) blood flow Infuse drugs into the femoral artery
Background Blood Flow Research
Two research questions:1. What are the neural, metabolic, and vascular
signals controlling blood flow at rest and exercise? 2. How do conditions like aging and cardiovascular
diseases (obesity, high blood pressure, etc) alter the regulation of blood flow
Wider implications understanding blood pressure control correlated with obesity, diabetics, and high
blood pressure
Background: Existing Devices Current device in use at Mayo Clinic Used part of an exercise bike and a car seat Boot is a rollerblade boot with the toe cut out Device was unreliable, and had variable forces
Background: Existing Devices Cont.
http://www.rehab.research.va.gov/jour/01/38/1/chin.html
http://www.hanix.net/en/powermax.htm
Design Requirements
Streamlined and compact with minimal loose parts
Minimum lifespan of five years Easily portable (with wheels) 5’ long x 3’ wide Chair positioned at various angles from
vertical and 3’ above ground Adjust for people of heights 5’4” to 6’4” Flexible range of motion for full leg extension
while kicking
Design Requirements
Passive return to rest position of the leg after kicking
Set up for right leg testing Wattage (0-100 W) and kick rate (30-60 KPM)
output to a laptop through an A/D converter Maintain a constant wattage throughout
testing Adjustable force between tests Under $2,000
Design Alternatives: Seat for pateint
Reclining Adjustable height
“Boot” for foot Straps to hold shoe
Adjustable force Wheels for movement Sensors
Wattage Kicking rate
Design Alternatives: Gas Spring Shock
Force from compression of gas in a cylinder Function of velocity
Can be purchased in various sizes with variable force Use a cable, allowing for full range of kicking motionDisadvantages Springs back to initial position
http://www.globalspec.com/FeaturedProducts/Detail/IndustrialGasSprings/Stainless_Steel_Gas_Springs_/34982/0?fromSpotlight=1
Design Alternatives: One Way Clutch
Allows rotation in only one direction
When clutch locks, friction device is engaged
When foot is returning, clutch freely rotates
Clutch attached to boot by a bar with ball joints
http://adcats.et.byu.edu/WWW/Publication/94-1/Paper1-12_6.html
http://www.mie.utoronto.ca/staff/projects/cleghorn/Textbook/DataFiles/Appendix-B/Appendix-B.html
Design Alternatives:with Drum Brake
Shoes push out against drum providing friction
Force is constant Adjustable by altering
force normal to drumDisadvantages Properties change with
heat Brake pedals need to
be replaced http://www.howstuffworks.com/drum-brake.htm/printable
Proposed Design:with Viscous Friction
Viscous friction for force against kick Two pieces of metal
with liquid between Force = μ*A*v / t Force altered by
changing area Force remains constant
through minor temperature changes
Rotating Axle
http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/Viscosity.htm
Design MatrixWeight
Gas Spring Shock
One Way Clutch w/ viscous friction
One Way Clutch w/ Drum Brake
Overall Reliability 20 0.75 0.9 0.65
Ease to Construct 5 1 0.8 0.8
Maintenance Required 15 0.8 0.8 0.6
Ease of Use 10 0.7 0.7 0.6
Consistent Force 15 0.6 0.8 0.6
Flexible Kicking Motion 10 1 0.8 0.8
Passive Kicking Return 20 0.25 1 1
Force Adjustability 5 1 1 0.7
Total (Out of 100) 68 86 72.5
Future Work
Finalize design Order components Construct design Test and modify
References Maximal Perfusion of Skeletal Muscle in Man (Per Andersen
and Bengt Saltin) 1984 Professor Fronczak ADCATS at Brigham Young University
http://adcats.et.byu.edu/WWW/Publication/94-1/Paper1-12_6.html