The latest addition to the growing field of fast four-legged robots is no bigger than a housecat, yet it can tackle more realistic terrain than its larger predecessors. Three years in the making, "Cheetah-cub" runs about 5 kilometers per hour and can descend steps up to 20% its leg length. For its size—23 centimeters long and 1 kilogram in weight—it may be a record-holder among other robo-quadrupeds, its developers say, attaining speeds seven times its body length per second. It even has an advantage over real cats: It runs with no brain telling it what to do. As researchers report today in the The International Journal of Robotics Research, Cheetah-cub self-adjusts its movement as needed because of three springs in each leg that adapt dynamically to the irregularities in its stride. The legs are modeled after a cat's, with three segments (think foot, calve, and thigh) moved via cables that connect to motors in the body. Power is supplied through a leash attached to the robot. The researchers hope to use the robot to study the biomechanics of animal locomotion and eventually to come up with quadruped robots that can be used in search and rescue operations.
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