At this point, Boston Dynamics’ robots look less like a single product and more like a vision of the future. Legged robots have been difficult to build for decades, but advances in a range of connected fields — including sensors, motors, control software, and machine vision — are making them viable for the first time.

Raibert says the difference between Spot and earlier legged robots is night and day. “It’s a tribute to what we’ve learned over the years in sensing the terrain, in balancing the robot, in controlling it,” he says. To reach this level the company has leaned on what Raibert calls “low-level AI.” That means artificial intelligence control systems that are responsible for keeping the machines upright and balanced in all situations. Actually telling the robot where to go and what to do is left to humans, who control Spot using a modified gaming tablet.

Legged designs have many natural advantages, says Lipson. They’re easy to balance and hard to knock over. They work in a wide variety of environments and are supremely adaptable. “This is why nature has so many legged machines,” says Lipson. “It’s a very versatile platform … I believe this will be the primary platform for future robotics.”