MIT researchers built a 70-pound robot "cheetah" meant to demonstrate the high efficiency of a new electric motor design. Among other improvements, the design enables the impact energy of the robot's leg hitting the ground to be captured and fed into the robot's battery. Soon, they expect the motors to enable the cheetah-bot to gallop at 35 mph which, of course, is still just half the speed of a real cheetah. However, it will hit those speeds much more efficiently than other running robots. From MIT:
Sangbae Kim, the Esther and Harold E. Edgerton Assistant Professor in MIT’s Department of Mechanical Engineering, says achieving energy-efficiency in legged robots has proven extremely difficult. Robots such as Boston Dynamic’s “Big Dog” carry heavy gasoline engines and hydraulic transmissions, while other electrically powered robots require large battery packs, gears, force sensors and springs to coordinate the joints in a robot’s leg. All this weighty machinery can add up to significant wasted energy, particularly when a robot’s legs need to make frequent contact with the ground in order to trot or gallop."MIT ‘cheetah’ robot rivals running animals in efficiency"