Now you can lie in your nice, comfortable MRI machine and control your robot. Or at least its hand. According to an article in the Japan Times, Honda and ATR have developed a system that can read MRI signals well enough to distinguish among a fist, an open hand, and a V sign in a few seconds, and order a robotic hand to perform a similar movement. (Yes, that's "gu, choki, pa", or "rock, scissors, paper".)
This is an improvement over other techniques for thought-controlled devices, which often require electrodes actually implanted in the brain, and/or require significant training of the user. The drawback is that it requires an entire MRI machine :-). I have no idea what this would do for Stephen Hawking, depends on which of his neural functions have deteriorated.