Electric Personal Assistive Mobility Devices
Electric personal assistive mobility devices are power-assisted devices for mobility such as wheelchairs, scooters, and more recent innovations such as the Segway™ Human Transporter. These devices make everyday life easier for someone who is partially or completely immobile.
Currently there are approximately 160,000 people who use electric powered wheelchair and scooters in the United States alone. Of these, some 100,000 utilize wheelchairs and 60,000 use powered scooters. As baby boomers become senior citizens and mobility becomes more of a concern for this large population, the market for these aids is expected to increase. Industry estimates show the powered assistive device market as growing by about 7% each year through 2007. By 2007, sales of manual- and electric-powered wheelchairs and powered scooters is estimated to be $2.7 billion in the United States.
Electric wheelchairs appeared in the 1950s. Then, the less sophisticated mechanics of the chair produced a rougher and more jarring ride. Today's models are better described as electronic chairs rather than electric chairs. Electronic circuitry allows for a control of speed and a precise control of direction. Many of today's sophisticated powered wheelchairs conform to two basic styles. The first is called the traditional style and consists of a power source mounted behind or underneath the seat of the wheelchair. As the name implies, the traditional unit looks very much like a manual wheelchair.
The second design is known as a platform chair. In this design, the seating area, which can often be raised or lowered, sits on top of the power source. There are several groups of powered wheelchairs, based on the intended use. Wheelchairs designed strictly for indoor use have a smaller area between the wheels, allowing them to negotiate the tighter turns and more confined spaces of the indoor world. Other designs allow the electric wheelchair to be used both indoors and outdoors, on sidewalks, driveways, and hard, even surfaces. Finally, some electric wheelchairs are able to negotiate more rugged terrain such as uneven, stony surfaces.
Wheelchairs meant for indoor and indoor/outdoor use conserve weight by reducing the size of the rechargeable batteries that deliver the power to the device. Outdoor models deliver more power, more speed, and can operate for a longer period of time, at the cost of a heavier wheelchair. Electric wheelchairs can also be classified according to the location of the wheels that drive the device. Rear-wheel, mid-wheel, and front-wheel drive models are available. In a rear-wheel chair, the big wheels that drive the unit are positioned behind the rider's center of gravity. This is the traditional chair design.
In the mid-wheel design, the large wheels are positioned directly under the rider's center of gravity. This offers a shorter turning radius, which can be useful in tight places. However, sudden stops can cause the chair to rock or pitch forward. Finally, the front-wheel drive chair has the large wheels in front of the rider's center of gravity. This allows for a tight turning radius and even to climb over obstacles such as curbs.
For people who are immobile, some wheelchairs are capable of adjusting the person's position. Some chairs can recline and/or can tilt people back while they are still in the sitting position. Changes of position relieve pressure and can help lessen the development of skin irritation.
Changing position can also help some people breathe more easily.
Some powered wheelchairs are also capable of raising or lowering a person. This can make life easier by allowing the person to retrieve fallen objects and to reach higher-placed objects. Some wheelchairs can even raise the person to a standing position. This increases the range of tasks a person can accomplish. A wheelchair-bound person can wash dishes, clean windows, work at a counter, and put dishes away in a cupboard, as a few examples, thus reducing the need to modify a home.
The controls to electric-powered wheelchairs vary depending on the mobility of the user. For those with arm function, a joystick can be used to propel the chair forwards or backwards, and to steer. Those who are paralyzed are able to perform these functions using a sip-and-puff setup via a straw. Some manufacturers even make voice-activated and -responsive wheelchairs.
This ability of fully paralyzed people to independently operate a wheelchair offers great potential in reducing the barriers that have prevented wheelchair users from participating fully in society.
Innovations in electric-powered wheelchairs
Construction materials used in wheelchair frames have reduced the weight of the chairs. Aluminum, stainless steel, and steel tubes are some of several materials that produce strength without excess weight.
In 1993, a new powered wheelchair marketed as the Hoveround was launched. It has features of both a wheelchair and a scooter. The most unique features are the round base and single rear wheel, which allow the chair to be turned in a full circle on the spot. A relatively recent innovation is known as the pushrim-activated power-assisted wheelchair (PAPAW). This design uses motors and an electric battery to supply forward thrust or braking capabilities that complement similar manual actions of the user. A PAPAW is best suited to a user who can manually operate a wheelchair, but not very efficiently due to pain, insufficient arm strength, heart and/or lung trouble, or inability to maintain effective posture.
User demand is driving new designs for mobility devices that do not look like wheelchairs. Indeed, newer designs for wheelchairs are more similar to scooters than to the traditional design of the wheelchair. The impetus for this new design has been people's desire for more independence and mobility, to the point of being able to mount curbs and travel over rough ground.
The Independence 3000 IBOT Transporter (IBOT) can change the way it moves in response to varying terrain. The two pairs of large rear wheels can operate at different height, allowing for actions like the mounting of curbs. In fact, the front pair of wheels can ride up the rear set, enabling the two pairs of wheels to balance vertically on each other.
Scooters are designed for people who are able to walk, but have difficulty walking significant distances. Examples include people with milder forms of cerebral palsy, multiple sclerosis, postpolio syndrome, and those who have had a stroke or who suffer from arthritis. Scooters are not designed for those who are absolutely immobile. Scooters consist of a seat mounted on a movable platform. The rider uses handle bars to maintain balance and to steer, although some scooters use electronics that control the steering instead of the operator. The seats are typically removable to allow the scooter to be easily transported in car, truck, or other vehicle.
Scooters represent a hybrid between a manual and electric wheelchair. They appeal to those who do not have
The basic setup of a scooter is known as the base unit. This consists of a frame made of steel or aluminum attached to a platform. Some units also have a windscreen as part of the unit. The seat post can be a permanent part of the frame, or may be detachable for easy transport.
Scooters can be front-wheel drive or rear-wheel drive. The scooters with rear-wheel drive, which has a larger motor and a longer distance between the front and rear wheels, typically supply more power and so are useful for tasks like climbing hilly terrain. Front-wheel drive scooters have a smaller motor and so are more maneuverable in tight places such as indoor use. They can also be used outside on flat, paved surfaces. The choice of scooter depends on the user's needs. Three- and four-wheeled scooters are also available. These provide more stability for users whose balance is faulty.
Other personal transport devices
For many years, golf cart-style vehicles have provided transportation for elderly people. In retirement communities, carts can be an everyday part of the landscape, being used even on the roads of gated communities. As the population ages and decreased physical mobility affects more people, the popularity of electric carts may well grow.
The Segway™ Human Transporter was introduced in the 1990s. It offers increased mobility for those with disabilities, but could also aid some persons who are unable to walk long distances. The machine operates on a principle called dynamic stabilization. Essentially, this means that the machine works in a manner similar to people's sense of balance. When people standing on the machine shift their center of gravity forward, the machine moves forward. Shifting the center of gravity backward stops the machine. There is no accelerator or brake.
While more of a curiosity than practical means of transport as of 2004, the transporter is an example of how increased mobility is possible in environments such as sidewalks and factories.
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Center for Inclusive Design and Environmental Access. School of Architecture and Design, University of Buffalo, Buffalo, NY 14214-3087. (716) 829-3485; Fax: (716) 829-3861. email@example.com. <http://www.ap.buffalo.edu/idea>.
Department of Rehabilitation Science and Technology. 420 Forbes Tower, University of Pittsburgh, Pittsburgh, PA 15260. (412) 383-6556; Fax: (412) 383-6597. firstname.lastname@example.org. <http://www.shrs.pitt.edu>.
Worldwide Education & Awareness for Movement Disorders (WE MOVE). 204 West 84th Street, New York, NY 10024. (212) 875-8312 or (800) 437-MOV2 (6682); Fax: (212) 875-8389. Wemove@wemove.org. <http://www.wemove.org>.
Brian Douglas Hoyle, PhD