Twenty-one humanoid robots joined thousands of runners at the Yizhuang half-marathon in Beijing today, the first time these machines have raced alongside humans over a 21km course. The robots from Chinese manufacturers such as DroidUP and Noetix Robotics came in all shapes and sizes, some shorter than 120cm, others as tall as 1.8m. One company boasted that its robot looked almost human, with feminine features. Some firms tested their robots for weeks before the race. Beijing officials have described the event as more akin to a race car competition, given the need for engineering and navigation teams. "The robots are…