Page 271 - Handbook of Electronic Assistive Technology

260 HANDBOOK OF ELECTRONIC ASSISTIVE TECHNOLOGY

Introduction

Powered mobility has traditionally been characterised as a wheelchair with batteries,
motors, gearboxes, drive wheels and a control system. While this provides a means to
define a particular type of statutory provision, it is somewhat restrictive. Manual wheel-
chairs may be powered by a variety of systems, including:
• Simple powered add-on units comprising a single motor, a single drive wheel sitting
between the rear wheels and a simple lever operated by an attendant (two wheels adjacent
to each other are used to provide more traction, but still operate at the same speed).
• Power-assisted (hub motor), push rim-activated wheelchairs, which amplify the effort
the occupant applies to the rims (Cooper et al., 2004).
• Hub motors controlled by a joystick operated by either the occupant or an attendant.
• Small drive wheels applied directly to the tyres, controlled with a joystick either by the
occupant or an attendant.

It is also possible to buy a manual wheelchair which converts into a powered chair by
removing the large diameter rear wheels and fitting a unit to the rear of the chair, inclusive
of the complete drivetrain. Scooters also provide powered mobility, albeit mainly for out-
door use, although some of the more compact versions are suitable for use indoors as long
as there is sufficient space for circulation. One might also include the Segway as a means of
powered mobility, although its usefulness will be defined by the person’s physical ability.

Indoor or Outdoor?

Powered wheelchairs can be designed specifically for indoor use, being characterised by a
compact design. In general, this will mean smaller batteries, which means a shorter range,
but this is less critical indoors, of course. It will also usually mean less outright stability,
the wheels being set closer together. Within the UK NHS these wheelchairs are classed as
electrically powered indoor wheelchairs.
Other wheelchairs are designed mainly for use indoors but also have a degree of capa-
bility outdoors (electrically powered indoor/outdoor wheelchairs), and some are mainly
for outdoor use with limited capability indoors, sometimes referred to as electrically pow-
ered outdoor wheelchairs. Care should be taken in making absolute definitions because
capability indoors will be defined by the indoor environment, the social context and the
occupant’s ability to control the chair in a confined space.
Further Variations

• Powered ‘ride-ons’ are available for very young children, designed specifically for that
age group in their context with other children of a similar age (e.g., WizzyBug from
Designability and Bugzi from MERU).
• Powered wheelchairs designed solely for use on rough terrain outdoors can navigate
ground that would be inaccessible to a wheelchair designed for use both inside and
outdoors.