Technology

How do you make a robot walk on Mars? It’s a sharp challenge


from Sojourner rover, which landed on Mars in 1997, to persistence, which landed in february, the robots of the Red Planet share a distinctive feature: wheels. Rolling over is more stable and energy efficient than walking, which is still even robots on the ground striving for perfection. After all, NASA hates having its very expensive Mars explorer toppling him like a turtle on his back.

The problem with wheels, however, is that they limit where rovers can go: To explore Mars’ complex hills like steep hills, you need the kinds of legs that evolution gave animals on Earth. So a team of scientists from ETH Zurich in Switzerland and the Max Planck Institute for Solar System Research in Germany manipulated Small four-legged robot call spacebook, designed to mimic the antelope known as Springbok.

True to his name, Springbok is real Jumps around the deserts of Africa, possibly to confuse predators. The original concept for the robot, introduced in 2018, was to actually jump on the surface of the moon, as astronauts did to navigate the lunar’s weak gravity. That might work on our satellite, where the landscape is relatively flat, but on Mars it’s probably too risky due to the complex terrain – full of sand, rocks and steep slopes. So researchers are now adjusting their limbs and gait to see if they can handle more brutal landscapes.

In these new experiments, the team programmed SpaceBok with a more traditional and less flexible gait. Specifically, the researchers wanted to compare two types: a ‘static’ gait, in which at least three limbs come into contact with the ground at any given time, and a ‘dynamic’ one, in which more than one end of the ground can leave. Once. The former is more systematic, but the latter is more efficient because it allows the robot to move faster.

The researchers also outfitted versions of SpaceBok with two types of feet: point and flat. The point foot has a small surface area, sort of like an actual spring hoof. By contrast, flat feet are actually flat, rotating circles, which bend at an angle when the foot contacts the ground. Think of these things more like snowshoes than hooves. Or they are similar to snowshoes with cleats, because they are studded with drops that help the foot grip the ground.

Note the large surface area of ​​the flat feet

Courtesy of Hendrik Kolvenbach / ETH Zurich

Once the researchers had different gait and foot configurations they could use to customize the robot, they placed it in a giant sloping sandbox loaded with soil affinity material found on Mars. This way, they can test if any of these configurations allow the bot to climb to a level of 25 degrees. By monitoring the robot’s use of energy, they can determine how efficient both the gait and foot configurations are.

at New prepress Description of the work that has been accepted for publication in the journal field robotsThey showed that the machine could skilfully and efficiently climb a simulated Martian hill without dropping it. “We wanted to show that these systems that operate dynamically nowadays, can indeed walk on the sands of Mars,” says Hendrik Colfenbach, an ETH roboticist in Zurich, lead author of the study. “This is a technology that has a lot of potential now in the future.”



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