Segway PT
The Segway PT is a two-wheeled, self-balancing, zero-emission, electric vehicle used for "personal transport". Segways have had success in niche markets such as transportation for police departments, military bases, warehouses, corporate campuses or industrial sites, as well as in tourism. The earliest patent resembling the modern Segway PT, U.S. patent #6,357,544, was filed on May 27, 1994 and issued to Dean Kamen on December 30, 1997. Kamen introduced his invention to the public in 2001.