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An Innovative Motorized Wheelchair for Young Disabled Children

Powered mobility for young disabled children is gaining increased acceptance1,4. Children as young as 11 months have demonstrated that within short periods of time they are able to learn to drive skillfully with parental supervision3,8. Researchers have reported more normal socioemotional and learning behavior of children who acquire independent mobility using powered wheelchairs and caster carts2,6. Overall development from earliest childhood is largely dependent on the ability to move freely. Until recently, powered mobility devices for the very young have been available only through the efforts of university design teams8 and creative parents. Commercial products designed principally for an older population require extensive modification for small children.

An innovative motorized wheelchair, the Turbo(r), (Fig. 1 ) was created by a British electronics design engineer, Daniel H. S. Everard, for his 18-month-old daughter who has spinal muscular atrophy. From Everard's understanding of children's mobility needs from infancy to preadolescence, a highly functional motorized wheelchair is now commercially available. Between August 1984 and January 1986, 90 Turbos(r) have been prescribed in the United Kingdom. Tables 1 and 2 show the diagnostic categories and age distribution of the recipients. Three children who have motorized wheelchairs used a Turbo(r) for an extended trial period at their elementary school. Immediate important changes in behavior were observed as a result of the additional freedom allowed by the vertical movement and the arrangement of the associated standing frame on the Turbo(r), as well as the ability to move in the upright position.

Design Features

The Turbo(r) resembles a miniature fork lift with 41 cm (16 in) diameter front pneumatic tires for good traction and 13 cm (5 in) diameter solid rear wheels. A built-in jack aids removal of the front tires for replacement with clean tires for indoor use. The rear tires, mounted on a centrally pivoting axle, enable the Turbo(r) to climb and descend curbs up to 10 cm (4 in) and to negotiate uneven terrain. The chassis (Fig. 2 ), 60 cm wide by 80 cm long (23 x 31'/2 in), is made of durable fiberglass in bright primary colors. The Turbo(r) weighs 86.4 kg (190 lb).

Two drive motors in the vehicle can propel children safely up a 1-in-4 grade. The occupant may be as heavy as 50 kg (110 lb), representing the 50th percentile for children approximately 14 years of ages. Top speed is 6.4 kilometers per hour (4 mph); acceleration and maximum speed can be controlled by inserting different electronic programs. Two 12-volt rechargeable gel-cell batteries, fully charged, run for 8 to 12 hours.

The easily removable plastic seat shell (Fig. 3 ) is available in widths of 25, 27.5, 30, and 32.5 cm (10, 11, 12, and 13 in), and is attached to a metal frame and mounted on a removable motorized lift (Fig. 4 ). When the seat is removed, an adjustable standing frame mounts on the lift shaft. The lift allows the driver to raise and lower the seat or standing frame independently between the ground and a maximum height of 65 cm (25 1/2 in). As the seat frame's hinged foot rest (Fig. 4 ) meets the ground, it is passively rolled forward.

The driver's control panel contains a proportional joy stick, a battery charge indicator light, horn, and up and down buttons. A parent control panel with a button to turn the drive motors off for 20 seconds is mounted on the chassis, facing rearward. An optional built-in microphone which reacts to the sound of whistle also stops the Turbo(r) for 20 seconds, allowing adults to intervene in case of emergency. A braking system which remains engaged unless the vehicle is being driven prevents free-wheeling when the Turbo(r) is stopped on an incline.

Behavioral Observations

Two children with cerebral palsy, aged 6 months and 10 years, used the Turbo(r) for one week in their classrooms in lieu of their regular motorized wheelchairs. Another 11-year-old boy with cerebral palsy had a shorter trial period. In their regular wheelchairs, the children could move independently throughout the building, but outdoors were restricted to level, hard surfaces. Sidewalk access was limited to infrequently placed curb cuts. In the classroom, the fixed height of the traditional wheelchair rendered the users dependent on adults to move the control boxes so that the children could maneuver close to desks and tables. Often they were restricted to designated work areas and special desks which fit their particular wheelchair height. The children spent approximately one hour during class time standing on prone boards to prevent contractures. During this time, activities were severely restricted because no self-initiated or controlled movement was possible.

Teachers reported similar behaviors for all three children who used the Turbo(r). Increased independence was immediately apparent. With variable seat height, the children accommodated themselves to any desk or table and could retrieve objects from the floor or from high shelves without assistance. In order to see better in group instruction, they adjusted their position by raising themselves slightly. During play, they lowered themselves to the ground to be level with playmates and then raised themselves and traveled to a new location for resumption of games. Outside, they were able to keep up with peers regardless of how rugged or soggy the terrain. Neighborhood travel became easy with the Turbo(r) as the children could manage any curb. Although the trial candidates were too physically disabled for independent transfer, other children could enter the Turbo(r) themselves by lowering the seat to the floor.

The most surprising observations were made with upright locomotion. Standing time tripled because now all activities, including independent mobility, could be continued while standing. The learning program which reduces the acceleration and speed was helpful to accustom the children to moving while standing. A rear support offers little interference with clothing, human interactions, or activities. Children explored the fronts of their bodies and parts of their clothing not reachable when sitting or on a prone board. They hugged and physically interacted with peers and their teachers more intimately. They worked at the chalkboard and other activity stations without having to lean forward out of the conventional wheelchair. Boys used a urinal independently. Turbo(r) users reached objects other children get to by climbing. They helped peers in new ways, such as when one driver pushed a non-mobile friend in her manual wheelchair.

Discussion

The innovative design of the Turbo(r) meets many criteria for small powered mobility devices?7,8. It is aesthetically pleasing, appearing more like a toy than a traditional wheelchair, enhancing its acceptance by the child, family, and community. The school staff, many of whom had never shown interest in wheelchairs, requested a staff meeting to learn more and were very enthusiastic.

The vehicle is hightly maneuverable indoors and outdoors. Being able to go up and down curbs and over rugged terrain expands the child's environmental accessibility and, therefore, participation in activities. When the seat and lift assembly are removed (Fig. 2 ), the chassis is extremely compact, facilitating its transport in automobiles, in contrast to traditional powered wheelchairs which are not easily transported without vans. New dimensions of mobility, available because of adjustable seat and standing frame heights, expand the child's reach, enabling users to obtain the physical and psychological benefits deriving from upright mobility.

In the United Kingdom, the plastic seat is usually lined with sheepskin (Fig. 1 ). The shell, however, easily accommodates custom positioning requirements, such as a total contact system. Joy stick placement can also be individualized. Growth is accommodated by replacing the plastic seat shell with a larger one and adjusting the standing frame without need to alter the chassis or lift assembly. Conceivably, one Turbo(r) could serve a child from age one year until the individual attained a weight of 50 kg (110 lb). The weight limit is determined, not by motor power, but by the load that can be carried in the seat or standing frame safely. Questions about long-term reliability, durability, and maintenance remain to be answered. The drive and brake belts, drive motors, and electronics appear to be well-protected from water and dirt to which the chair is exposed during routine use.

Safety features include the mechanical braking system, engaged except when the Turbo(r) is driven. This increases its suitability for hilly environments. Even when moving at top speed, it will stop quickly when the driver's hand leaves the joy stick. By switching programs for the electronic control mechanism, the acceleration and speed can be tailored to the skill, experience, and maturity of the driver. One program, suitable for children with athetosis, dampens the effect of adventitious joy stick movements. The chassis cover provides a suitable flat surface to support an adult trying to instruct or supervise a juvenile occupant, and can be used to carry additional equipment such as a ventilator. The parent control panel and build-in microphone give a watchful adult the ability to stop the vehicle by pushing a button or blowing a whistle when a driver encounters danger.

Powered mobility is a developmentally appropriate intervention for many young disabled children. The innovative aspects of the Turbo(r) offer distinct advantages, making it an invaluable addition to the armamentarium of adaptive equipment. Turbo(r) is now marketed in the United States and Canada by Invacare Corporation, 899 Cleveland Street, Elyria, OH 44036.

Acknowledgment

We acknowledge the assistance of Pat Schuppenhauer in preparing this manuscript

*Department of Rehabilitation Medicine, Children's Orthopedic Hospital and Medical Center 4800 Sand Point Way NE, Box C5371, Seattle, WA 98105

**Seattle Public Schools, 2143 North Northlake Way, Seattle, WA 98103

***Everaids Ltd., 172 Cambridge Road, Great Shelford, Cambridge CB2 5JU, England

References:

  1. Breed A.L., and E. Ibler: The Motorized Wheelchair: New Freedom, New Responsibilities and New Problems. Dev Med Child Neurol 24:366-371, 1982.
  2. Butler, C.: Effects of Powered Mobility on Self-Initiated Behaviors of Young, Locomotor Disabled Children. Dev Med Child Neurol 28:325-332, 1986.
  3. Butler, C., G. A. Okamoto, and T. M. McKay: Powered Mobility for Very Young Disabled Children. Dev Med Child Neurol 25:472-474, 1983.
  4. Motorized Wheelchair Driving by Disabled Children. Arch Phys Med Rehabil65:95-97, 1984.
  5. National Center for Health Statistics: NCHS Growth Charts, 1976. Monthly Vital Statistics Report. 25: (Supp. 3) 1976. 76-1120.
  6. Paulsson, K., and M. Christoffersen: Psychosocial Aspects of Technical Aids-How Does Independent Motility Affect the Psychosocial and Intellectual Development of Children with Physical Disabilities? In Proceedings of 2nd International Conference on Rehabilitation Engineering. Ottawa, 1984. 282-285.
  7. Warren, C. G.: Wheelchairs for the Severely Disabled. In Wheelchair III: Report of a Workshop on Specially Adapted Wheelchairs and Sports Wheelchairs. RESNA, Bethesda, 1982. 55-59.
  8. Zazula, J. L., and R. A. Foulds: Mobility Device for a Child with Phocomelia. Arch Phys Med Rehabil64:137139, 1983.