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98 PS | Bipedal robots R obotics design company Boston Dynamics has specialised in UGVs that get around on legs rather than on wheels or tracks (writes Peter Donaldson). As they look and move like people or animals, they tend to be thought of more as robots than vehicles, potentially conjuring up the kind of apocalyptic visions depicted in movies such as the Terminator series. That is a long way from reality though, and draws attention away from the real engineering achievements involved in mastering legged – particularly two-legged – locomotion on rough, slippery terrain. Humans’ more cerebral achievements in spheres such as mathematics, chess and codebreaking were long assumed to be more difficult for computers to master than the apparently simple actions of balancing, walking and so on, and manipulating objects. The reverse turned out to be true though. In WW2 for example, the bombes at Bletchley Park in the UK cracked the German Enigma codes, and later, in 1996, IBM’s Deep Blue beat world chess champion Garry Kasparov. Building robots that could master mammal-like locomotion, however, proved more difficult. The processing power required to fuse inputs from multiple sensors and calculate how to coordinate the responses of actuators is enormous compared with that required to play chess, for example. Boston Dynamics has done it, however, and its creations move very well under remote control. One of its latest, dubbed Handle, is a roughly humanoid ‘biped’ with wheels instead of feet. Handle is designed to provide what the company calls agile, high-strength mobile manipulation, along with the rough terrain mobility of legs and the flat-surface efficiency of wheels. Standing 2 m tall, Handle weighs 105 kg and can carry a payload of up to 45 kg, which it can pick up and set down using its arms. Battery powered, it uses hydraulic as well as electric actuation, has 10 articulated joints – equivalent to hips, knees and so on – and uses cameras for depth perception. Although less complex than the company’s other legged robots, Handle uses many of the same principles for dynamics, balance and mobile manipulation found in its quadrupedal and bipedal creations. It can also manoeuvre in tight spaces. A feature that enables it to keep a load stable while it is on a moving surface or travelling over undulating ground is endpoint control, which is illustrated in a YouTube video showing that its ‘hands’ remain still while the robot performs a series of dips as if it were holding onto an invisible horizontal bar. The angles of the joints in its arms and legs make it appear to roll backwards much of the time, although it can also reverse direction. The video shows Handle jumping over obstacles, running one of its wheels up a ramp while the other stays on the ground, leaning into turns and leaping onto a long table, rolling down some steps out of a building and down a snow- covered bank into a car park. While it can be pushed over, albeit with considerable effort, it uses its ‘hands’ to help push itself back onto its wheels. All this shows that robots can now be almost athletic, although combining such physical prowess with the ability to navigate autonomously through complex, unstructured environments is a challenge that has yet to be mastered. Now, here’s a thing “ ” In the video, Handle jumps over obstacles, leans into turns, leaps onto a long table and rolls down some steps December/January 2019 | Unmanned Systems Technology