Peter Fankhauser, co-founder of the ETH spin-off that is commercialising ANYmal, radios his colleagues on the surface, who are responsible for coordinating the test and sending commands to the robot. Fankhauser then twiddles with a joystick and the robot plods forward. As this is the first test in unknown terrain, he takes partial control of the robot even though it is capable of moving autonomously. “It’s a precautionary measure,” says Fankhauser, “Just because something works in the lab doesn’t always mean it will in the real world.” After all, the conditions underground are not what the robot is used to: the chamber is wet and slippery, with lower temperatures and higher humidity than in the lab. What’s more, it’s very, very dark.

“It’s hard to distinguish much down here,” says Fankhauser, almost with a hint of resignation in his voice, as the robot moves at a slow pace through the roughly three-metre-high and five-metre-wide tunnel. The robot emits a uniform electromechanical sound – a kind of rhythmic whirring – that blends with the sound of rushing water emanating from the main sewer nearby. We are in quite a large overflow sewer with only a trickle of water in it. Given that the robot is on its maiden test run four metres below ground ­level, the researchers have taken the precaution of avoiding large volumes of water.

Finding its way in the dark

The goal of the three-year research project entitled THING (sub-Terranean Haptic InvestiGator) is to design robots that can move about on their own and are better able to identify their surroundings. Robots generally use 3D cameras and laser sensors for orientation. But such devices can malfunction in adverse conditions – such as when the ground surface is wet or the air full of dust. That’s why the researchers consider enhanced haptic perception – orientation by touch – to be a possible solution. The project has brought together ETH researchers with colleagues from universities in Edinburgh, Pisa, Oxford and Poznań.

All these institutions are experimenting with ANYmal robots, and the project participants from the various locations meet up on a regular basis. In addition to the tests in the sewerage system, next year the researchers will deploy the robot in a Polish copper mine. That will determine whether it can function in an entirely different microclimate, one characterised by hot, dusty air and gravel surfaces. ETH is represented in the project by the Laboratory for Robotic Systems led by Professor Marco Hutter, who has been conducting research into legged robots for many years. He received support from ETH soon after embarking on this research in the form of an ESOP scholarship and a Pioneer fellowship.

One of the key questions on this first day of testing is whether the robot can find its way around at all in the darkness of the sewerage system. Initially, two helpers with big LED lamps illuminate the surroundings so that we can clearly see what’s going on. Then, Fankhauser asks the helpers to turn off the lamps and radios his colleagues on the surface to tell the robot to use its own lights. The robot’s sense of touch isn’t the only thing that helps it find its way in the dark, as Hutter explains: “The robot uses laser sensors and cameras to scan its surroundings. By identifying irregularities in the surface of the concrete, it can determine where it is at any given moment.”

All that can be seen in the darkness now are the small round LEDs in the robot’s “head”. The atmosphere is other-worldly: the darkness, the sound of rushing water, the electromechanical whirring, the robot’s LED eyes. Then someone breaks the eerie silence ­momentarily with a droll comment: “Its eyes are a bit like a Rottweiler.”

Underground and offshore