Apptronik, a fast-growing startup that makes artificial intelligence-powered humanoid robots, has secured about $520 million in a new funding round that values the company at more than $5.5 billion, around three times its valuation from its initial Series A raise last year.The funding round was led by existing investors including Google, Mercedes-Benz Group AG and B Capital, along with new investors AT&T Ventures, John Deere & Co. and the Qatar Investment Authority. This investment is an extensi...