Lecture 18 Dimitar Stefanov

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

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.)

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

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

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

Categories of wheelchairs (continue) Stand-up wheelchairs LifeStand, USA, http://www.lifestandusa.com/home.htm

Stair-climbing wheelchairs LEVO, Switzerland, http://www.levo.ch/ Gas spring activated Electric activated Stair-climbing wheelchairs

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.

Patient transfer systems

Beach wheelchairs Scooters http://www.beachwheelchair.com/ Shoprider, http://www.dcc-shoprider.com/

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

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).

Center of gravity (COG) Located among the midline of the person and the chair

COG – location Seat width – as narrow as possible; usually 1 inch higher than the user’s hips Frame angle

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

Caster flutter Rapid vibration on the front wheels The caster flutter occurs when there is no enough trail.