The world's first full-length marathon for two-legged robots kicked off in Japan on Thursday, with the toy-sized humanoids were due to run 42.195 kilometres (26 miles) over four days.
The machines began the non-stop race on a 100-metre (109-yard) indoor track in the western city of Osaka after doing knee bends or raising their hands to greet spectators.
The bipedal robots -- the tallest of which measures 44 centimetres (17.6 inches) -- must complete 423 laps to reach their goal.
The "Robo Mara Full" race is organised by Vstone Co., a robot technology firm based in the western industrial city, in cooperation with the Osaka prefectural government.
Competitors are allowed to change batteries and the so-called servomotors which control the robots' speed and other functions.
Robovie-PC from Vstone led the race at the start. Video footage from a camera in its head can be seen at http://www.ustream.tv/channel/robovie-pc.
A wide view of the race can be seen live at here.
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