IT’S not just humans who find it difficult to run on sand. Even the most nimble robots struggle when faced with a stretch of the white stuff.
Planetary rovers and earthbound rescue robots often need to travel across varying terrain, including sand and rubble. So , a biophysicist at the Georgia Institute of Technology in Atlanta, investigated what makes these surfaces such a challenge.
His team studied a robot called Sandbot – which has six C-shaped legs and scampers across hard ground with the agility of a cockroach – as it waded through a bath full of poppy seeds. The density of the seeds was controlled by blowing air through the bath.
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They found that if Sandbot’s limbs moved a fraction too fast, or if the researchers loosened the packing between the grains even slightly, the robot would quickly switch from a walking motion to an ineffectual swim as it sank deep into the material.
He believes the answer is for robots to be built with sensors that detect how compact a surface is, and to vary their limb motion accordingly (Proceedings of the National Academy of Sciences, ).
