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Four Bar Linkage in Exercise Equipment
Group CRobert “SolidEdge” Desjardins
Stephanie LouttitMark Szymanski
Christopher “GUI” Wirz
Overview
Four Bars in Exercise Equipment Elliptical Gait Grashof & DOF SolidEdge Simulation Instant Centers MATLab Simulation Varying Parameters
Four Bars in exercise machines!
Four Bars in exercise machines!
Four Bars in exercise machines!
Elliptical Exerciser - Classification
r1 + r2 < r3 + r4
Grashof Class I Kinematic Chain
Crank-Rocker
r2
Elliptical Exerciser - DOF
L = 4 J1 = 4 DOF = 3(L – 1) – 2(J1) –J2 DOF = 3(4 – 1) – 2(4) DOF = 1
2
1
3
a
4
c
b
d
Elliptical Exercisers
A combination of a stair climber and a cross-country ski machine that you stand on and pedal
No impact Less likely to injure joints than on a
treadmill Lower perceived exertion for
equivalent workout intensity
Walking/Running
When walking, feet naturally follow path of ellipse While foot 1 is flat on
the ground, foot 2 is in the air moving parallel to the ground
When running, feet pound (impulse) on the ground potentially causing joint injury
Elliptical
Elliptical exercisers eliminate impact with the ground by following the natural motion of the feet
Elliptical Exerciser SolidEdge Simulation
Elliptical Exerciser SolidEdge Simulation
Elliptical Exerciser SolidEdge Simulation – Velocity Plots
Instant Centers
Elliptical Exerciser MATLab Simulation
Matlab GUI for elliptical.zip
Normal “Standard” “Plebian”
This is the motion profile for the elliptical machine
Varying Parameters
r1 r2 r3 r4 r5 t1 t5
Normal 50 8 33 34 12 40 167
Model 50 5 33 34 12 60 180
Vince 50 16 33 34 12 40 180
Arnold 50 12 33 34 12 40 220
Bush 50 8 33 34 12 47 145
Krovi 50 8 33 34 12 40 200
But then we got the celebrities to try out our new elliptical machines!
Model
Vince Vaughn
Arnold Schwarzenegger
President Bush
Dr. Venkat Krovi
Conclusions
Most elliptical exercisers are not adjustable for different heights and stride lengths of people
By varying r2, the stride length can be tuned to different criterion
Further research could be performed in changing the shape of the foot path for example: from elliptical to figure
eight
Questions