Beyond marathons and backflips, China’s robots face a commercial test

China’s humanoid robot makers have spent the past two years dazzling investors with machines that can breakdance, throw punches and ​even set marathon records. This week in Beijing, they face ​a tougher test in proving their inventions can work reliably to generate economic value.

More than 300 companies are expected at ​the World Robot Conference from Wednesday through Sunday, showcasing over 2,000 exhibits and launching more than 150 products, according to Beijing authorities.