Serial Wheelchair Control Interface Standard

Trace Center Project Team:
Joseph M. Schauer, BSEE; David P. Kelso, MS; Gregg C. Vanderheiden, PhD

Background

As electronic communication aids and environmental control devices become more advanced, their ability to perform more sophisticated functions expands. As a result of this increased capability, there is a growing interest in interfacing suitable assistive devices (such as communication aids) to wheelchairs. In this model, the aid assumes the control functions typically performed by the joystick or other standard control built into the wheelchair.

However, devices such as communication aids can only be used as controls if they can be effectively interfaced to the wheelchair. At the present time, special aids must be individually customized for each model of wheelchair they are to be used with. No common interfaces exist among powered wheelchair controllers, but several manufacturers are interested in developing them.

To assist in the development and application of new control devices, Trace Center engineers began developing a protocol for a standardized connection. As long as both the control and the wheelchair conform to the specifications of the standard, any manufacturer's control device can be used with any manufacturer's wheelchair.

Figure 1.

[Figure 1 under the Serial WheelChair Control Interface Standard shows two scenarios. The first scenario is a line drawing of the current wheelchair control model. In the first scenario, for a wheelchair to interface to anything other than a simple control joystick requires that a custom interface be built.

The second scenario in the Serial WheelChair Control Interface Standard shows a line drawing of the same wheelchair, only this time with the addition of a standard interface (e.g., the serial control model), many devices such as an intelligent joystick or a communication aid can easily be interfaced to the wheelchair.]

Approach

The standard was discussed in meetings of wheelchair manufacturers, communication aid manufacturers and researchers at the annual RESNA conferences in 1988, 1989 and 1990. A RESNA subcommittee on wheelchair standards has been created to review and further develop the standard. Since RESNA is the representative on wheelchair issues to ANSI, the standard is also under consideration for adoption by ANSI. RESNA, through ANSI, submitted an application to the International Standards Organization (ISO) to establish a working group on the standard within ISO. In November, 1990 ISO established the working group (ISO/TC173/ scl/WG-7).

Status

The ISO Serial Interface for Electronic Wheelchair Controllers has evolved into a more sophisticated standard called the M3S Standard. Copies of the draft ISO standard are available to interested parties from the ISO, ANSI or RESNA.

Selected Publications

Schauer, J.M., Vanderheiden, G.C., & Kelso, D.P.(1990). Serial wheelchair control interface standard. Madison: University of Wisconsin, Trace Research and Development Center.

Schauer, J.M., Kelso, D.P., & Vanderheiden, G.C.(1990). Development of a serial auxiliary control interface for powered wheelchairs. Proceedings of the Thirteenth Annual RESNA Conference. Washington, DC: RESNA.

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