Powered bipedal robots based on unpowered walking toys

Unpowered bipedal devices which walk down gentle slopes have been in development, initially as toys, for more than one hundred years. Here we describe three powered robots based on these ramp-walking toys. Humanoid walking robots usually rely heavily on complicated feedback control strategies, have a limited learning ability, have gaits that look somewhat artificial, and use relatively more energy to walk than humans. In contrast, our robots have highly simplified control strategies. One of these is quick to learn a variety of motions. One can walk on somewhat uneven terrain. And one uses an order of magnitude less energy than previous powered bipedal robots. The natural and efficient motions of these minimally-controlled artificial animals support the idea of a similar coupling between structure and motion in real animals.