A reinforcement learning system enabled a four-legged robot to amble over unfamiliar, rapidly changing terrain.

What’s new: Researchers at UC Berkeley, Facebook, and Carnegie Mellon developed Rapid Motor Adaptation (RMA). The system enabled a Unitree Robotics A1 to negotiate changing conditions and unexpected obstacles nearly in real time. The machine traversed muddy trails, bushy backcountry, and an oil-slicked plastic sheet without falling.

How it works: The system includes two algorithms, both of which are trained in simulation. The reinforcement learning component learns to control locomotion basics, while the adaptation module learns to generate a representation of the environment.

In deployment, the two algorithms run asynchronously on a single edge device. They analyze the previous 0.5 seconds of data from limbs and joints and adjust the gait accordingly.
In tests, the robot maneuvered through conditions that it hadn’t encountered in simulations, such as a squishy foam mattress, over piles of rubble, and rough-hewn staircases. It repeated many of the tests carrying loads of varying weight.
The machine achieved 70 percent or better success in each scenario. When it fell, the mishap typically was due to a sudden drop while descending stairs or debris that blocked more than one leg.

Behind the news: Video clips of robots from Boston Dynamics and others have become viral sensations in recent years. They may be mouth-watering, but the bots involved often are programmed for specific motions or scenarios and can’t adapt to novel conditions.

Why it matters: RMA is among the first robotic walking systems that don’t need to be trained for every variety of terrain they're likely to encounter.

We’re thinking: For many applications where navigating flat ground is sufficient, wheeled locomotion is much simpler and more reliable. But legs still carry the day when navigating rough terrain — not to discount their uncanny anthropomorphic appeal. They’re likely to be important for tasks like fighting fires, traversing disaster zones, and navigating the toy-strewn obstacle course that is Andrew’s daughter's playroom.

Rapid Motor Adaptation

Walking the Dog

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