Robotics section in the PCT article

I have just recaptured the section on robotics that Rupert put into the “Perceptual control theory” article in November 2017. Greyfell deleted that section on 26 November 2020 as seeming to be self-promotional. Since I have edited, added other citations, and am not any of the people cited, it’s safe from that problem now. It would be good for Rupert and others to review what I have done.