Motorized wheelchair
Encyclopedia
A motorized wheelchair, powerchair, electric wheelchair or electric-powered wheelchair (EPW) is a wheelchair
that is propelled by means of an electric motor
rather than manual power. Motorized wheelchairs are useful for those unable to propel a manual wheelchair or who may need to use a wheelchair for distances or over terrain which would be fatiguing in a manual wheelchair. They may also be used not just by people with 'traditional' mobility impairments, but also by people with cardiovascular
and fatigue based conditions.
, to assist injured veterans during World War II
.
Powerchairs are generally four-wheeled and non-folding, however some folding designs exist and other designs may have some ability to partially dismantled for transit.
Four general styles of powerchair drive systems exist: front, centre or rear wheel drive and all-wheel drive. Powered wheels are typically somewhat larger than the trailing/castoring wheels, while castoring wheels are typically larger than the castors on a manual chair. Centre wheel drive powerchairs have castors at both front and rear for a six-wheel layout.
Powerchair chassis may also mount a kerb-climber, a powered device to lift the front wheels over a kerb of 10 cm or less.
Some manual wheelchairs may also be fitted with an auxiliary electric power system. This can take one of three forms: integrated with the hub of hand-propelled wheels, so that any force on the pushrims is magnified by the drive system, or mounted under the wheelchair and controlled as for a powerchair, but with the motive force either transmitted to the main wheels via a friction drive system, or delivered directly through an auxiliary drive wheel.
Some experimental all-terrain powerchair designs have been produced with tracks rather than wheels, but these are not in common use.
Other experimental designs have incorporated stair-climbing abilities and Dean Kamen
's iBOT
design featured both stair climbing and the ability to 'stand' on its up-ended chassiss via the use of advanced gyroscopic sensors. The iBOT was at one time a production model, but is no longer marketed.
deep-cycle rechargeable batteries
, similar to those used to power outboard boat engines
. These are available in wet or dry
options. As wet-cell batteries may not legally be carried on an aircraft without removing them from the wheelchair and securing them in a shipping container, dry-cell batteries are preferred for powerchair use. Many powerchairs carry an on-board charger which can be plugged into a standard wall outlet; older or more portable models may have a separate charger unit.
which may have additional controls to allow the user to tailor sensitivity or access multiple control modes. The controller may be swing-away to aid in side-transfers. For users who are unable to use a hand controller various alternatives are available such as sip-and-puff
controllers, worked by blowing into a sensor. In some cases the controller may be mounted for use by an aide walking behind the chair rather than by the user. Capabilities include turning one drivewheel forward while the other goes backward, thus turning the wheelchair within its own length.
'Thought-control' of powerchairs, actually working by the detection of brainwaves or nerve signals via sensors on the scalp or elsewhere, has been demonstrated in the laboratory environment.
Certain high-end powerchairs feature a 'standing' capability in which either the entire seat elevates to bring the user to standing height or the seat-base, seat-back and leg rests move in conjunction to bring the user into an upright position. The powerchair may or may not be able to move while in the elevated position.
Some very large outdoor powerchairs have been designed with cross-country mobility in mind and show design convergence with other types of cross-country vehicle.
and some private insurers) and the UK (National Health Service
) powerchairs are generally not prescribed to users who have any ability to walk within the home, even if that ability is so functionally constrained as to be practically useless and where the user is unable to use a manual wheelchair independently. Disability rights activists are campaigning for prescription procedures to focus on an individual needs based assessment rather than on inflexible application of prescription rules. The restricted prescribing leads to many users being forced to procure a solution privately, in some cases settling for a powerchair or a mobility scooter
that is less than ideal to their needs but which falls within their budget.
The use of powerchairs is not restricted solely to users unable to use manual chairs. Any disabled person with a mobility, fatigue or pain-based impairment or cardio-vascular issues may find a powerchair advantageous in some circumstances, however existing prescription practises generally means that powerchairs for such use must be privately procured or hired for the occasion.
s are frequently designed around a typical manual wheelchair (in the UK referred to as a 'reference wheelchair'). Powerchairs, however, frequently exceed the size and weight limits of manual wheelchairs as they are not constrained by the ability of the user to self-propel. Some designs are too large or heavy for certain wheelchair spaces and lifts.
Wheelchair
A wheelchair is a chair with wheels, designed to be a replacement for walking. The device comes in variations where it is propelled by motors or by the seated occupant turning the rear wheels by hand. Often there are handles behind the seat for someone else to do the pushing...
that is propelled by means of an electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
rather than manual power. Motorized wheelchairs are useful for those unable to propel a manual wheelchair or who may need to use a wheelchair for distances or over terrain which would be fatiguing in a manual wheelchair. They may also be used not just by people with 'traditional' mobility impairments, but also by people with cardiovascular
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
and fatigue based conditions.
History
The electric-powered wheelchair was invented by George Klein who worked for the National Research Council of CanadaNational Research Council of Canada
The National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...
, to assist injured veterans during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
.
Design
Powerchair design may be categorised by drive system/chassis, battery, controller, seat, and use.Drive System/Chassis
Four general styles of powerchair drive systems exist: front, centre or rear wheel drive and all-wheel drive. Powered wheels are typically somewhat larger than the trailing/castoring wheels, while castoring wheels are typically larger than the castors on a manual chair. Centre wheel drive powerchairs have castors at both front and rear for a six-wheel layout.
Powerchair chassis may also mount a kerb-climber, a powered device to lift the front wheels over a kerb of 10 cm or less.
Some manual wheelchairs may also be fitted with an auxiliary electric power system. This can take one of three forms: integrated with the hub of hand-propelled wheels, so that any force on the pushrims is magnified by the drive system, or mounted under the wheelchair and controlled as for a powerchair, but with the motive force either transmitted to the main wheels via a friction drive system, or delivered directly through an auxiliary drive wheel.
Some experimental all-terrain powerchair designs have been produced with tracks rather than wheels, but these are not in common use.
Other experimental designs have incorporated stair-climbing abilities and Dean Kamen
Dean Kamen
Dean L. Kamen is an American entrepreneur and inventor from New Hampshire.Born in Rockville Centre, New York, he attended Worcester Polytechnic Institute, but dropped out before graduating after five years of private advanced research for drug infusion pump AutoSyringe...
's iBOT
IBOT
The iBOT is a very stable and mobile powered wheelchair developed by Dean Kamen in a partnership between DEKA and Johnson and Johnson's Independence Technology division. It is a medical technology, made to help people with severe mobility problems....
design featured both stair climbing and the ability to 'stand' on its up-ended chassiss via the use of advanced gyroscopic sensors. The iBOT was at one time a production model, but is no longer marketed.
Battery
The electric motors of powerchairs are usually powered by 4 or 5 ampAmpere
The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...
deep-cycle rechargeable batteries
Rechargeable battery
A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible. Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to...
, similar to those used to power outboard boat engines
Outboard motor
An outboard motor is a propulsion system for boats, consisting of a self-contained unit that includes engine, gearbox and propeller or jet drive, designed to be affixed to the outside of the transom and are the most common motorized method of propelling small watercraft...
. These are available in wet or dry
Dry Cell
-Dry Cell's formation:Part of the band formed in 1998 when guitarist Danny Hartwell and drummer Brandon Brown met at the Ratt Show on the Sunset Strip. They later met up with then-vocalist Judd Gruenbaum. The original name of the band was "Beyond Control"....
options. As wet-cell batteries may not legally be carried on an aircraft without removing them from the wheelchair and securing them in a shipping container, dry-cell batteries are preferred for powerchair use. Many powerchairs carry an on-board charger which can be plugged into a standard wall outlet; older or more portable models may have a separate charger unit.
Controller
Controllers are most commonly an arm-rest mounted joystickJoystick
A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks, also known as 'control columns', are the principal control in the cockpit of many civilian and military aircraft, either as a center stick or...
which may have additional controls to allow the user to tailor sensitivity or access multiple control modes. The controller may be swing-away to aid in side-transfers. For users who are unable to use a hand controller various alternatives are available such as sip-and-puff
Sip-and-puff
Sip-and-Puff or Sip 'n' Puff ' technology is a method used to send signals to a device using air pressure by "sipping" or "puffing" on a straw, tube or "wand." It is primarily used by people who do not have the use of their hands...
controllers, worked by blowing into a sensor. In some cases the controller may be mounted for use by an aide walking behind the chair rather than by the user. Capabilities include turning one drivewheel forward while the other goes backward, thus turning the wheelchair within its own length.
'Thought-control' of powerchairs, actually working by the detection of brainwaves or nerve signals via sensors on the scalp or elsewhere, has been demonstrated in the laboratory environment.
Seat
The seating on a powerchair may be little more than the sling seat found on low-end manual wheelchairs, but is generally more substantial, frequently a 'captain's chair' design. Head rests are a common adaption and specialist seating solutions are available for users who need individually tailored support. Leg rests may be integrated into the seating design and may have powered adjustment for those users who need to vary their leg position. Powerchairs may also have a reclining facility for users who are unable to maintain an upright seating position indefinitely.Certain high-end powerchairs feature a 'standing' capability in which either the entire seat elevates to bring the user to standing height or the seat-base, seat-back and leg rests move in conjunction to bring the user into an upright position. The powerchair may or may not be able to move while in the elevated position.
Environment
Powerchairs may be designed for indoor, outdoor or indoor/outdoor use. Some indoor chairs may actually resemble a conventional armchair and have neglibible ability to deal with obstacles. Indoor/outdoor chairs generally give more consideration to their size and the need to navigate within a home environment than do outdoor chairs.Some very large outdoor powerchairs have been designed with cross-country mobility in mind and show design convergence with other types of cross-country vehicle.
Use
Powerchairs are generally prescribed for use by users who are unable to use a manual wheelchair. However in both the US (MedicareMedicare (United States)
Medicare is a social insurance program administered by the United States government, providing health insurance coverage to people who are aged 65 and over; to those who are under 65 and are permanently physically disabled or who have a congenital physical disability; or to those who meet other...
and some private insurers) and the UK (National Health Service
National Health Service
The National Health Service is the shared name of three of the four publicly funded healthcare systems in the United Kingdom. They provide a comprehensive range of health services, the vast majority of which are free at the point of use to residents of the United Kingdom...
) powerchairs are generally not prescribed to users who have any ability to walk within the home, even if that ability is so functionally constrained as to be practically useless and where the user is unable to use a manual wheelchair independently. Disability rights activists are campaigning for prescription procedures to focus on an individual needs based assessment rather than on inflexible application of prescription rules. The restricted prescribing leads to many users being forced to procure a solution privately, in some cases settling for a powerchair or a mobility scooter
Mobility scooter
A mobility scooter is a mobility aid equivalent to a wheelchair but configured like a motorscooter. It is often referred to as a power-operated vehicle/scooter or electric scooter as well.-Description:...
that is less than ideal to their needs but which falls within their budget.
The use of powerchairs is not restricted solely to users unable to use manual chairs. Any disabled person with a mobility, fatigue or pain-based impairment or cardio-vascular issues may find a powerchair advantageous in some circumstances, however existing prescription practises generally means that powerchairs for such use must be privately procured or hired for the occasion.
Limitations
Access adaptions such as wheelchair spaces on public transport and wheelchair liftWheelchair lift
A wheelchair lift, also known as a platform lift, is a powered device designed to raise a wheelchair and its occupant in order to overcome a step or similar vertical barrier....
s are frequently designed around a typical manual wheelchair (in the UK referred to as a 'reference wheelchair'). Powerchairs, however, frequently exceed the size and weight limits of manual wheelchairs as they are not constrained by the ability of the user to self-propel. Some designs are too large or heavy for certain wheelchair spaces and lifts.