Limbed Robots At The Beach
Writing by Evan Ackerman on Tuesday, 10 of February , 2009 at 6:08 am
While robots are getting better at moving over rough terrain, unstable or shifting surfaces still pose quite a challenge. Generally, legs (which are much more adaptable than wheels) are pretty lousy at moving through sand, and researchers at the Georgia Institute of Technology are trying to figure out why that is, and how to get around it.
SandBot, which is quite similar to Boston Dynamics’ RHex, is designed to explore the dynamics of robot movement on a granular surface, in this case, poppy seeds. The problem with granular surfaces like sand is that the surface can shift rapidly from a solid to what’s basically a liquid, and this shift can be caused by the robot itself trying to move, which gets you into a cycle that can cause the robot to start to bury itself. In tests, researchers found that very small changes in the consistency of the sand (as little as a 1 percent volume change) and the gait of the robot translated into either stable movement, or or slower and less stable “swimming.”
As you might expect, a large part of the stability of the gait was controlled by how far each limb penetrated into the sand. It’s not just due to weight distribution, though… As the limbs sink into the sand, the gait of the robot is shortened, and it begins to take its next “step” into an area of sand that the limb in front has already disturbed, causing it to sink further. The basic rule when this starts to happen is to slow the gait down, but there are a bunch of other relevant variables including limb angle and acceleration. The researchers hope to take the model that they’ve developed and use it to help robots better autonomously and dynamically adapt to variable terrain.
[ Georgia Tech Press Release ] VIA [ Physorg ]
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Category: Research
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