Last year, we wrote about HyQ, a quadruped robot designed for rough terrain missions. Created by a team at the Istituto Italiano di Tecnologia (IIT), HyQ was learning to walk and trot, and was also able to jump and even kick things. The robot uses hydraulic actuators, which allow it to move quickly and nimbly, with an eerie animal-like quality. Now HyQ has learned another important skill in life: how not to fall on its face when it stumbles on an obstacle. Falling is a major problem for legged robots. Unlike animals and (most) humans, robots don't handle falls very well. Their stiff metal bodies can't absorb shocks, and a crash often means broken parts and costly repairs. So robots designed to operate in real-world conditions need to learn how to avoid falls at all costs (a prime example of that is another quadruped, the famous BigDog, and let's not forget its bigger brother LS3, both from Boston Dynamics). Cameras and sensors like LIDAR help detect and avoid obstacles, but in some situations a robot can't rely on vision—for example, in thick vegetation or if smoke is present. To overcome this obstacle (quite literally), HyQ is learning to reflexively react when its legs hit an object on the ground. This reaction has to be very fast, especially when the robot is trotting (HyQ can reach 2 meters per second), or else it will lose its balance and collapse. The IIT researchers developed and implemented a "reflex algorithm" that allows HyQ to step over high obstacles without prior knowledge of the terrain.