Similar in size to Boston Dynamics' BigDog, the HyQ hydraulically-actuated quadruped robot can walk, trot, kick, and jump, but its reflexes need an upgrade before it can move from flat ground to more challenging terrain. To that end, researchers from the Italian Institute of Technology's (IIT) have developed an animal-like step reflex algorithm that quickly detects when the robot's feet run into obstacles, preventing trips and falls.

Legged robots like IIT's HyQ were designed to go where other types of robots cannot, but they're not much use if they trip over small obstacles like fallen logs or concrete steps. Robots such as the LS3 from Boston Dynamics typically use a sensor head equipped with LIDAR and cameras to detect major obstacles ahead of time to plan the safest route.


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HyQ's sensor head is still in the works, so for now it essentially feels its way forward. HyQ's legs are compliant, allowing the robot to detect and absorb external forces acting on its legs. The step reflex is triggered if the robot detects that the foot motion is obstructed, and causes it to automatically lift that leg over and above the obstruction.

The robot is capable of running at speeds up to 2 meters per second (4.4 mph), so this has to happen within a fraction of a second for it to work. Even then, it doesn't always catch something, similar to when a person steps on something unexpectedly. In that case, it initiates the step reflex the next time it moves its foot. It's good enough to bypass obstacles up to 11 cm (4.3 in) high.

Currently the research team at IIT's Dynamic Legged Systems Lab is working on HyQ's vision system and dynamic gaits. The lab is also toying with the idea of adding a pair of arms to the robot, in a centaur-like configuration, which would allow it to interact with objects in its environment. In the mean time, they'd like to begin testing its reflexes in a wooded area later this year.

They're not alone, having recently sold one of the robots to ETH Zurich's Agile and Dexterous Robotics Lab. With similar ambitions, the two labs are working together to accelerate the development of legged robots. And today IIT researchers will be displaying the robot publicly at London's Natural History Museum as part of the Living Machines conference.

The step reflex algorithm, which can be seen in action in the following video, was presented at the Climbing and Walking Robot conference in mid-July.

Source: HyQ project via IEEE Spectrum

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