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