Lecture 18 Dimitar Stefanov Wheelchairs and Personal Transportation

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 • 1940 s – 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 • 1995 s – omni-directional wheelchairs

Categories of wheelchairs: 1. Manually powered 2. 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 Life. Stand, USA, http: //www. lifestandusa. com/home. htm

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

Frame design – lightweight tubes Frame styles: 1. Box-frame wheelchairs (great strength and rigidity) 2. 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. 1. Pneumatic casters 2. 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.