A robot dog has learned to open doors with its leg

A robot dog can use a leg to open doors, press buttons and pick up rucksacks while balancing on its other three legs. Four-legged robots like Spot, the star of Boston Dynamics' viral videos, normally need an arm attached to their body to open doors or pick up objects, but this can add significant weight and make it harder for the robot to squeeze through narrow spaces. Philip Arm at ETH Zurich in Switzerland and his colleagues used a machine-learning model to teach an off-the-shelf robotic dog to use one of its legs to perform tasks while standing still or moving with the other three legs. "We cannot do everything with the legs that we could do with an arm – right now, a hand is way more dexterous. But the point is really to make this work for applications where you maybe have mass constraints, or we don't want to have that additional complexity, like for space exploration where every kilogram of such a robot counts," says Arm.