Dimitar Stefanov - PowerPoint PPT Presentation

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Dimitar Stefanov

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Title: Dimitar Stefanov


1
Lecture 18
  • Dimitar Stefanov

2
Wheelchairs and Personal Transportation
  • Some history
  • Centuries ago transportation of the disabled on
    hammocks slung between poles that were carried by
    others (upper class people)
  • Wheelbarrow similar to these for transportation
    of materials
  • During the Renaissance first wheelchairs arm
    chairs with wheels placed on them (France)
  • Wooden wheelchairs until 1930

3
  • Franklin D. Roosevelt metal kitchen chairs
    modified with wheels
  • Civil War   First record of wheelchairs being
    used in the United States.
  • 1907  First patent applied for a folding
    wheelchair with a steel frame.
  • 1936  First single cross-brace steel wheelchair
    patented by Everest Jennings Everest (mining
    engineers), Jennings (engineer)
  • ErnestJennings first company for wheelchair
    manufacture few years later
  • World War II steel-framed wheelchairs with 18
    inch seat width
  • 1940s first powered wheelchairs, standard
    manual wheelchairs adapted with automobile
    starter motors and automobile battery
  • Rigid power wheelchair frame free space under
    the seat (battery, controller, respirators, etc.)

4
  • 1948  Removable armrests introduced.
  • 1950's  Lightweight chairs developed for sports
    use.
  • 1980's-present  New composite frame materials
    developed to further reduce the weight of chairs.
  • Personal automobile modified control of the
    standard automobile
  • Microcars enlarged powered wheelchairs, speed
    about 10 km/h
  • The first voice-activated power wheelchair was
    used in 1984 by a student 
  • 1995s omni-directional wheelchairs

5
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6
  • Categories of wheelchairs
  • Manually powered
  • Electrically powered
  • 200 000 wheelchairs are sold annually within the
    USA
  • 20 000 powered wheelchairs

Depot wheelchairs for institutional use,
several people may use one and the same wheelchair
One-arm-drive wheelchairs linkage connection of
the rear wheels
7
Indoor and outdoor wheelchairs
Indoor wheelchairs short wheelbases, less
stable in lateral direction
  • Wheelchairs, powered by the user
  • Wheelchairs, powered by attendants

Ultra light wheelchairs
Sports wheelchairs
8
Categories of wheelchairs (continue)
Stand-up wheelchairs
LifeStand, USA, http//www.lifestandusa.com/home.h
tm
9
LEVO, Switzerland, http//www.levo.ch/
  • Gas spring activated
  • Electric activated

Stair-climbing wheelchairs
10
Patient transfer systems
Vivax Medical, http//www.vivaxmedicalcorp.com/
Consists of a specially designed electric
(hospital type) bed and wheelchair.       The
Vivax Mobility System has a transfer conveyor
system integrated into the bed frame which moves
the patient from the bed into a specially
designed wheelchair and back again.  A built in
air support system provides true pressure relief
and a low-shear comfortable bed surface.
11
Patient transfer systems
12
Beach wheelchairs
http//www.beachwheelchair.com/
Scooters
Shoprider, http//www.dcc-shoprider.com/
13
Frame design lightweight tubes
  • Frame styles
  • Box-frame wheelchairs (great strength and
    rigidity)
  • Cantilever frame wheelchairs (the frame can act
    as suspension fewer tubes)

Box-frame wheelchair
Cantilever frame wheelchair
14
Materials
  • Aluminum (6061 aluminum tubing) lightweight,
    high corrosion resistance,
  • Steel (chromium- molybdenum alloy) easy to
    welding, wall thickness 0.028 inches, diameter
    0.25-1.25 inches
  • Titanium lightweight, strong require special
    tooling, high cost
  • Composite materials (carbon fibers) extremely
    strong and tough, lightweight
  • Two basic styles of powered wheelchairs on the
    market
  • The traditional style, and
  • the platform-model powered chair (powered base
    and a chair on it).

15
Center of gravity (COG)
Located among the midline of the person and the
chair
16
COG location
Seat width as narrow as possible usually 1
inch higher than the users hips
Frame angle
17
Wheels and caster
Front casters from 50 to 200 mm in diameter for
manual wheelchairs for daily use.
  • Pneumatic casters
  • Polyurethane casters

Rear wheels wheels with large diameter
18
Caster flutter
Rapid vibration on the front wheels
The caster flutter occurs when there is no enough
trail.
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