What you are looking for is the ibot wheelchair. It was invented by Dean Kaman who also invented the Segway. It uses some of the same technology used in the Segway. He licensed J&J to market and sell it. Unlike the Segway it is FDA approved and cost about $25,000.00.
Below is a link to the J&J site with info on the ibot.
http://www.jnj.com/innovations/new_features/IBOT.htm