Robotics experts at the Swiss Federal Institute of Technology in Zurich (ETH Zurich) have taught the four-legged robot dog ANYMal from ANYbotics to climb a normal standard ladder. This is a problem that has so far remained largely unsolved. Only a few robots even manage to climb a ladder – and if they do, then only very slowly.
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Scientists at ETH Zurich have managed to modify an ANYMal robot dog so that it can quickly climb a ladder. In the study “Robust Ladder Climbing with a Quadrupedal Robot”which appeared in preprint on Arxiv, the scientists describe the underlying process.
The researchers initially struggled with the fact that the ANYMal robot dog only had rubber paws. As with other robot dogs, these are ideal for running on different surfaces, but not for climbing ladders, as slipping off the rungs is possible.
When climbing a ladder, people generally use their hands to grasp the rungs of the ladder and hold on securely. The robotics team at ETH Zurich therefore developed a corresponding hooked paw so that the robot dog can also hold on to a rung. They taught the robot how to use the hook using reinforcement learning.
Simulation and imitation
The researchers accelerated the training using a privileged teacher-student approach. In simulations, the robot dog climbed different types of ladders, including those with intentional interference. These include ladders that wobble or have individual rungs missing. The scientists specifically observed the robot’s behavior for the disturbances. If problems arose, the researchers trained the robot dog manually in the simulation by showing it how to react in a specific situation. The robot dog was able to understand this through imitation, so it learned robust climbing skills in a short period of time.
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The scientists transferred the training data from the simulation to an ANYMal robot dog and tested its skills on different real ladders under laboratory conditions. In about 90 percent of cases, the robot was able to climb the ladder safely. The hooked paws made a big difference compared to the robot dog’s normal paws.
The roboticists at ETH Zurich now want to further increase the precision of climbing and teach ANYMal to climb ladders in unstructured environments. In addition, the researchers intend to forego motion capture without negatively affecting climbing performance.
(olb)
