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Casali's invention solves wheelchair mobility problem

By Liz Crumbley

Spectrum Volume 18 Issue 08 - October 12, 1995

The solution to a major mobility problem for wheelchair users has been developed in the Virginia Tech Industrial and Systems Engineering (ISE) Department's Human Factors Engineering Center.

John G. Casali, ISE interim department head, has two U.S. patents pending on his invention of an affordable, compact attachment that can quickly and easily turn a manual folding wheelchair into a steerable power chair. The device is unique in that it can be temporarily fitted to the frame of any standard folding wheelchair, adding both motive power and steering capability.

Currently, the more than 1.2-million wheelchair users in the United States have three alternatives: manual folding chairs that are lightweight and easily transportable, but offer no relief from the fatigue of hand-propelling; rigid-frame power wheelchairs that are heavy, expensive (typically more than $6,000), and must be transported in a special van equipped with a lift; and manual chairs with rear-mounted power units that so far have been expensive, heavy, and impossible to transport in the front seat of a car (where they would be accessible to a non-ambulant driver).

Casali's invention is a lightweight power-drive attachment that can be sold commercially for less than half the price of rigid- or folding-frame power chairs. A 12-volt battery powers a single DC electric motor that turns a drive wheel through a speed-reducer gearbox. The drive wheel is suspended on a coil spring that forces it against the ground, maintaining contact over variations in terrain.

The unit is configured as a slender vertical column designed to be attached to the front frame of the wheelchair, by a seated user, with quick-connect fittings. This is a unique featureæother commercial power units affix to the rear of a wheelchair, requiring an attendant for attachment and detachment.

Casali's attachment allows 360 degrees of steering control via a straightforward tiller column, and can turn a chair within its own length. The invention offers two other unique features: the user can enter and exit the chair and the chair can be operated manually, both with the power unit attached. Preliminary reviews by users and rehabilitation engineers have indicated that the unit is impressive in its simplicity of design and the ease with which it can be attached by non-ambulant users.

Owners of Casali's invention won't need vans equipped with lifts to transport their power-drive wheelchairs. The power attachment can fit in the front seat of most cars, and a manual folding chair is typically stored behind the driver's seat.

The two-year design project is sponsored by the Virginia Center for Innovation Technology (CIT) in Herndon and Southwestern Applied Technologies (SWAT) in Roanoke. Casali credits Louis Berneman, the CIT's licensing and business director, and L. Thompson Hanes, president of SWAT, with providing the initiative and means for building the prototype of the power attachment. Randy Waldron of the ISE Research Machine Shop fabricated the prototype. Laura Clark, an ISE Ph.D. student in Human Factors Engineering, performed user-needs assessments and developed design alternatives.

During the project's second year (1995-1996), the design team will improve the prototype, conduct performance and usability tests, develop an instruction manual for users, and produce an informational demonstration videotape. Independent experts and wheelchair users will conduct detailed design reviews of the power-drive unit before it is refined and packaged as a marketable prototype.

Casali has assigned the rights for the technology to Virginia Tech and the CIT, and hopes that it will improve the quality of life for wheelchair users who can benefit from the powered mobility it provides. Casali projects that, if all goes well with a commercial licensee and manufacturing capabilities, a consumer version can be marketed by 1997.