JASON DITMARS, BRIAN DUGGAN, and RONEN MINTZ
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Virtual Wheelchair Interface Ramp: A Change in Perspective
The purpose of the Virtual Wheelchair project is to provide an interface between a user in a wheelchair and a computer. This interface takes the form of a ramp. The user rolls up the ramp until the wheels of the wheelchair are positioned and lowered into two sets of rollers. Optical encoders and an interface box translate the motion of the wheels to the computer, allowing wheelchair navigation through a computer generated environment.
Custom software, including navigation code specifically for wheelchairs, was designed by Brian Duggan at the San Diego Supercomputer Center. This software uses the Performer libraries by Silicon Graphics. Models are created by Jason Ditmars with Maya and imported directly into Performer via a custom tri-file loader. The interface ramp -- made of steel, diamond plate, expanded metal, and electronic devices -- was constructed in Los Angeles by Ronen Mintz and Jason Ditmars. The ramp can be used by both physically challenged persons in their own variety of wheelchairs (electric or manual), as well as by others in a standard wheelchair (provided on site).
The wheelchair was chosen not only for its commonly understood operation, but also for its symbolic representation. In operation, many people find difficulty using a Trackball, 6D Tracker, or Mouse to navigate virtual space, resulting in a frustrating experience. The wheelchair, by contrast, is a navigational device that everyone already understands. It enables movement through this new spatial terrain in a more familiar way. The wheelchair alone represents mobility for the physically challenged. As an interface, it becomes a metaphor for a new kind of mobility that exists in cyberspace and other computer-generated spaces, where the limitations of the body are left behind.
By making an interface specifically for wheelchairs, the experience is accessible to the entire public. This interface is excellent for public shows or public spaces such as conventions or museums. People who are bound to wheelchairs become the expert navigators -- able to maneuver around the space with ease. People who are not bound to wheelchairs are asked to engage the experience by using a common wheelchair provided on site. Even children and senior citizens, who are not necessarily experienced with computers, have been able to quickly adapt to this intuitive form of navigation.
The ramp consists of four main parts and is adjustable to various lengths. The full interface consists of a five foot front ramp, a three foot middle platform, and a three foot back ramp. It is a total length of 11 feet, at a maximum height of 7 1/2 inches. The front ramp can be made steeper and shorter, giving a total length of 9 feet. A minimum space arrangement can be made by using the front ramp for both entrance and exit, bringing the total length down to 6 feet.
Only one person is required to assist a user in boarding the interface ramp. Once users roll up to the middle platform, they are easily lowered into position by an extension lever. At this point, motorized wheelchairs are ready to go. Manual wheelchairs can be locked into an adjustable device that lifts some of the weight off of the rollers so that the wheels are easier to spin. Once the experience is finished, the assistant raises and locks the wheels back to the level of the platform surface and the user can roll forward and coast down the ramp.
To spice things up a bit, we added a lever/joystick that lets the user fly up into the virtual sky, affording a wonderful birds-eye-view of the buildings of various shapes and colors. A button box allows for selection between FAST and SLOW navigation speed. FAST is commonly used for electric wheelchairs that have more precise wheel movements, while SLOW is more representative of real-world navigation for manual wheelchairs.
The next stage of the project is to incorporate force-feedback motors into the ramp. These motors will be used to reflect real-world gravity and friction. Thus, if you are on a virtual hill, the wheels of your wheelchair will begin to coast forwards. To stop yourself, you will have to brake the wheels with your hands, just as you would in the real world. With this system installed, we believe the wheelchair ramp will be one of the most submersive physical interfaces to date.
V. Shows and Awards
Butler Institute of American Art, Youngstown, OH -- Mar.19-Aug.19, 2000
Permanent Display at the San Diego Supercomputer VisLab, La Jolla, CA -- 1995-1998
Siggraph '95 Interactive Communities (w/ Cityspace) -- Aug. 1995
Los Angeles Convention Center, Los Angeles, CA
Supercomputing '95 (w/ Cityspace) -- Dec. 1995
San Diego Convention Center, San Diego, CA
Nominated by the Discovery Channel for the 1995 "Invention of the Year"
This project has received generous support from: