University researchers are designing a wheelchair that can climb stairs on its own. Imagine a wheelchair that can leap tall flights of stairs in a single bound. That lofty goal is what motivates the University researchers working on a prototype wheelchair which they hope will one day allow anyone in a wheelchair access to any building through any entrance. Researchers in the University's General Robotics and Active Sensory Perception lab have developed a wheelchair that could eventually eliminate the need for ramps by adding climbing capabilities to the standard wheelchair. Envisioning a wheelchair that could eventually negotiate stairs, beaches or even large hills, GRASP's mechanical engineers are working on a prototype "all-terrain" wheelchair with legs. Now in its third version, the chair consists of an ordinary plastic seat built upon a platform with rubber wheels. The current version of the chair, which is capable of pulling a 60-lb. load up a flight of stairs, can only negotiate stairs which are spaced at least a foot apart. The wheelchair, which was patented by the University in 1995, climbs stairs and maneuvers over uneven terrain by planting two mechanical legs into the ground ahead of the chair. The chair, which operates on 24 volts of power -- the equivalent of two car batteries -- then uses the leverage created by each leg to pull itself forward. Mechanical Engineering Professor Vijay Kumar, who is overseeing the project, said researchers hope that the "walking" wheelchair will eventually be produced commercially. "We have had some bites, but nothing concrete," Kumar said of corporate interest in the chair. It would be "a dream come true" if the project were to become commercial, Kumar added. But he explained that the new wheelchair will have to overcome industry prejudices. "The wheelchair industry is a very stodgy, conservative type of industry," he noted. "They see robotic technology as 50 years downstream. But it's here now. We already have robot vacuum cleaners." The project has been funded by a three-year, $180,000 grant from the Whitaker Foundation of Rosslyn, Va., which supports bio-medical engineering research. While the prototype costs between between $20,000 and $30,000 to build, producing the actual chair for sale would cost much less, according to Kumar. The prototype, however, is "completely without the bells and whistles" that one might associate with a commercial design, said Venkat Krovi, a Mechanical Engineering graduate student involved with the project. "But it's functional," Krovi added, explaining that the project's goal was simply to make a working wheelchair prototype. Although the original prototype is a model and was not designed to carry a person, the current version of the wheelchair is capable of moving a weight of up to 60 pounds up stairs. "The first prototype was too heavy to get off the ground," Kumar explained. The second prototype, based on a commercially made wheelchair, was able to climb stairs. But the chair's high center of gravity made it less stable, and its underside failed to clear stairs properly. The biggest problems in creating the vehicle were determining the best dimensions -- which became the subject of Mechanical Engineering graduate student Parris Wellman's masters thesis -- and finding ways to coordinate the various motors to pull the chair up and over a stair, the focus of Krovi's masters thesis. A large part of the work involved trying out different ways to position the components, according to Krovi, who spent long hours tinkering with mathematical models to determine the best places to position the chair's parts. But after completing the chair, Krovi said that"the feeling that 'I built this' is something very few other things can match."
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