SHENZHEN — On December 29, for the first time in the Hong Kong Stock Exchange, it was not a man but a humanoid robot that struck the gong. Striding down the red carpet, the 1.45 meter, 77 kg Walker S held the mallet firmly between his articulated fingers to launch the IPO of UBTech, the Chinese company that created him. Founded in 2012 in Shenzhen, UBTech doesn’t just intend to make history on the Hong Kong Stock Exchange. It also wants to revolutionize industry and human services by taking robotics into a new era: that of artificial bipeds, capable of interacting with humans. All this under i…