CHICAGO -- A stair-climbing wheelchair, which includes elements of a tank in its design, is now available for people with disabilities.
The chair can roll over curbs and climb wide staircases, according to Anthony Castagna, president of Quest Technologies, Sunnyvale, Calif., which manufactures the device.
But the chair's expensive: it costs $27,000.
The maximum angle the chair can tackle is 36 degrees, which covers about 90 percent of all staircases, said Mr. Castagna, who described the wheelchair yesterday at the annual meeting of the American Association for the Advancement of Science here.
When faced with a physical obstacle, the chair, called the Access Mobility System, pauses to assess the task: Its sensors emit ultrasound waves to measure the angle of the ascent or descent and decide whether it is safe to proceed.
To climb or descend it deploys two tank-like tracks that keep it from sliding. On a flat surface, the chair retracts the tracks and uses wheels that enable it to attain a speed of up to six miles an hour.
Before ascending, the wheelchair approaches the staircase backwards and tilts its passenger to the back to balance the center of gravity.
"The idea of not being able to see where you are going is somewhat unsettling," said David Ross, biomedical engineer at the Veterans Administration Medical Center in Atlanta, who has seen Access in action. "You have to go with some trust that the thing is going to work, but it does work fine."