they use something called "force control" which I think uses a spring to act as some kind of tendon. http://news.nationalgeographic.com/news/2003/03/0311_030313_... http://web.mit.edu/spotlight/archives/troody.html Mentions some of the engineers at Boston Dymanics including the inventor of troody. https://prezi.com/tn5kji7ehk3u/prezi-project/
more info here: http://news.mit.edu/2001/dinosaur We use series elastic actuators, or springs connected to motors, and low-stiffness control, so the joints are looser, and more biological." HOW IT WORKS Troody, which weighs about ten pounds, has 16 joints and 36 sensors. "Every joint has a position and force sensor," Mr. Dilworth said. The robot also has a vestibular system -- the equivalent of an inner ear -- that i…
Re: Ask HN: What are the modern approaches to robotic control?
#21We use series elastic actuators not so the joints are more biological, but mainly so that motors don't get creamed when the robot bumps into something and so that the robot doesn't cream whatever it bumps into. The second reason why we do this is to get force/torque control. Series elastic actuators measure force or torque by measuring the deformation of a spring. You get increased force bandwidth at the expense of decreased position bandwidth