FOLDING THREEWHEEL WHEELCHAIR:

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FOLDING THREE-WHEEL WHEELCHAIR Most Critical
Module Presentation
Amanda Maguire, Neeharika Bhartiya, Andrea
Blakemore, Rebecca Hung
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FINAL DESIGN
L-SHAPED BRACKET Modified x-brace (look
like hockey sticks) Two L-braces Front of
seat Back of seat Center rod comes directly
out of center of bracket Force on seat will hold
back rest in tension and lock bracket open
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MOST CRITICAL MODULE
MCM Folding mechanism (aka the L-brace
itself) Why? Most important part of our
folding wheelchair would be what makes it
fold Most significant change from previous
designs Mathematically the most difficult part
to design Most accurate approximation of how
small chair will get ? can design rest of
chair based on these dimensions Need to know
these dimensions to determine rest of
dimensions for chair
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IMPORTANT COMPONENTS
What are the forces on each member of the
chair? Will the bars be able to handle these
forces? Will the mechanism fold? What are the
ideal dimensions so that the chair folds as small
as possible?
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Calculating Center of Mass
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FORCES
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FORCES ..continued
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FORCES ..continued
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FORCES ..continued (Front and Back Braces)
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FORCES ..continued
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FORCES ..continued
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Constrained or Not?
14 Variables
F1, F2, F3, F4, R1, R2, R3, R4, R5, R6, R7, R8,
T, Tb
14 Equations CONSTRAINED!
Full Wheelchair FBD(2), Shaft and front wheel
(2), Seat Cushion(1), One side of Front L brace
(3), One side of Back L brace(3), Center Plane
(3)
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FOLDING
DEMONSTRATION Lindsay Todmans prototype
for the folding wheelchair she is working on for
her senior thesis Same mechanism as our design,
but hers has different dimensions Can still be
used to show that the mechanism will work and
will fold the chair up
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DIMENSIONS
Set Dimensions (in) W16, h11,L10, a30 Solve
For w, l, (1) Optimized Dimensions Maximize
(1), minimize w
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FINAL DIMENSIONS
Set Dimensions w 3.5 in (based on size of
folded Roughrider) Solve For l 8.87 in ß
25.4 (1) 3.8 (3)7.2
Thank you Excel!
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Most Critical Module Prototype
Demonstrate Prototype With Our Dimensions!
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OTHER COMPONENTS
Now that our MCM is worked out, we still need to
design/build Center rod (length? how will we
attach front castor?) Seat (dimensions? how
tall is backrest?) Sides of frame (how does we
attach wheels to frame?) Armrests (shape?
height?) Footrests (material? placement? how to
attach?)
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NEXT STEPS
Week of May 11th Final Presentation with Working
Prototype Week 1 Evaluate MCM and make
modifications if necessary (or totally redesign
if that is necessary) ?COUNTERMEASURE
Design other components of wheelchair (see
previous slide) Week 2 Decide final way
of incorporating all components together
Buy components Week 3 Alter existing
chair to incorporate L brace (BUILD!) Week 4
Make changes/improvements as necessary
Test complete chair with all components
integrated
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ANY QUESTIONS?