Honda Motor Co. has unveiled an electric battery-powered personal transporter, a unicycle shaped like the number eight that riders steer by leaning in the direction they want to travel.

The "U3-X," which Honda will show at the Tokyo Motor Show next month, is the latest to join a growing number of futuristic transportation devices, such as the much bigger Segway.

But while the Segway has been used outdoors and in big buildings, the 65 centimetre tall Honda machine is small enough and light enough to use at home.

Honda's machine has a one-wheeled, "8"-shaped body on which the rider sits and changes direction by leaning forward, backward or sideways. It moves at a maximum speed of 6 kph, about the pace of brisk walk.

The self-balancing U3-X, weighing in at less than 10 kilos, is powered by a lithium-ion battery and runs for an hour per charge.

Honda chief executive officer Takanobu Ito told reporters the machine could one day become the smallest means of transportation for human beings, though it is purely in the development stage and the automaker has no plans to start selling them now.

Ito said the U3-X's small size would make it an ideal indoor transport device.

"If my legs get a little weak, I would like to have this around in my house. It's easy to move around," said the 56-year-old CEO.