THE world’s first full-length marathon for two-legged robots kicked off in Japan today, with toy-sized humanoids due to run 42km over four days. The machines began the non-stop race on a 100m indoor track in the city of Osaka after doing knee bends or raising their hands to greet spectators. The bipedal robots – the tallest of which measures 44cm – must complete 423 laps to reach their goal. The “Robo Mara Full” race was organised by Vstone, 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.