RHEX Better Than Walking
Written by Lucy Black   
Sunday, 28 July 2013

While there has been a lot of progress in humanoid robots that walk like us, there is the alternative view that the whole "robots that look like us" is a silly idea. RHex is a hexapod that goes places that two legs would have a lot of difficulty with.

Bipedal locomotion is easy for us, but for a robot it uses a lot of computing power and it still doesn't seem to work. Why bother? After all more legs make a more stable platform. But more legs equals more complexity and more software to control their positions. Wheels don't have anywhere near the number of degrees of freedom, but we all know the problem with wheels - it is why Daleks can't get up stairs to exterminate you.

Well RHex probably could do the job.



RHex uses a cross between wheels and legs, sometimes called wegs, to move in a way that is a lot like an insect and yet not quite. 

The simplest way to explain how it works is via a video of it in action: 


There have been insect-like robots before that scuttle at high speed in a sort of uncontrolled scramble. Even RHex is based on an original designed ten years ago. What is interesting about RHex is that it uses a controlled scramble. Yes, it does rely on its light weight to ensure that when it throws itself at a target it doesn't come to harm and there is a some luck in its jumps landing right, but its use of its legs is far from a random scramble.

A new prize-winning paper describes a "vocabulary of legged leaping". In other words, given you have six "legs" how can you use them to climb over things:

"By activating its legs in different sequences, RHEX can execute double jumps, flips, and, through a combination of moves, even pull-ups. For the tallest obstacles, the robot can launch itself vertically, hook its front legs on the edge of the object it's trying to surmount, then drag its body up and over."

Basically the vocabulary is a set of subroutines for each of the standard moves. With the new software the robot can go places that were previously beyond its reach - literally, as it can now jump and cross obstacles that are bigger than it is. Hardware is great but software makes it so much better. 



More Information

Toward a Vocabulary of Legged Leaping

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Last Updated ( Monday, 29 July 2013 )