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)
Ernest&Jennings – 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

6. Categories of wheelchairs: Manually powered Electrically powered
wheelchairs are sold annually within the USA
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,

9. Stair-climbing wheelchairs
LEVO, Switzerland,
Gas spring activated
Electric activated
Stair-climbing wheelchairs

10. Patient transfer systems
Vivax Medical,
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 Scooters http://www.beachwheelchair.com/
Shoprider,

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 – inches, diameter – 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 user’s 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.