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Subject: 
Re: Legged Robots
Newsgroups: 
lugnet.off-topic.geek, lugnet.robotics, lugnet.technic
Date: 
Thu, 22 Jul 2004 17:54:03 GMT
Viewed: 
3390 times
  
In lugnet.space, Leonard Hoffman wrote:
   http://www.discover.com/issues/jul-04/departments/biomechanics-of-cockroaches/

I was reading the July issue of Discover (quickly becoming one of my favorite magazines) at the library and found an article about development of robotic leg locomotion.

what follows is my narrative/impression of the article since I can’t link to a full text of it. I personally am very intrigued by the real-world versions of our sci-fi/fantastical ideas. The issue also contains information about the proposed Space Elevator.

Leonard, I found the article on robotic leg motion very interesting. I hope to find time to play with springy legs in the near future.

Kevin

http://www.kclague.net

  

The guy, Robert Full, says that legs are first and foremost, springs. And that the springing motion follows that of a sine curve. Two legged creatures, like us, he says, really just bounce around on two pogo sticks. Interestingly enough, all legs have the same amount of bounce - regardless of species or size. It takes one joule of energy to move 2.2 pounds of body a distance of 3.3 feet.

But the really fascinating part of the article is the discussion of the benefit of this type of locomotion over traditional robotic bipeds and wheels. Traditional robot-bipeds and wheeled robots are such that at any given moment they are fully stable. Organic movement (springy movement) is such that at any moment it is unstable - constantly falling from unstable position to another.

This means that Springy Motion, by being unstable at moments, creates greater overall stability. Full attached a small jet pack on a roach’s backside. The jet was programed to fire sideways (relative to the roach’s movement) and knock the roach off balance. Everytime the jet fired, the roach was able to regain balance within 10 milliseconds, which is faster than any possible neural reflex. This means that the roach brain doesn’t need to devout any effort to maintaining its balance; this effort can be redirected into other activities like figuring which way to go, etc.

Applying this to LEGO Robot and Bot construction, this means that Pedal robots are more realistic (given a future timeframe) than wheeled robots - or at least, they have the potential of being equally or even more efficient in their locomotive abilities.

enjoy!
-Lenny

Burdick, Alan. “The Biomechanics of Cockroachs: Building the Perfect Pest.” Discover vol. 25 #7 pg24 - 25



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