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Subject: 
Re: Walkers
Newsgroups: 
lugnet.robotics
Date: 
Sat, 10 Feb 2001 15:03:04 GMT
Original-From: 
Harley Myler <h.myler@{nomorespam}myler.org>
Viewed: 
511 times
  
At 5:37 PM -0600 2/9/01, Steve Baker wrote:
Harley Myler wrote:

What you really want to ask here is "Has anyone built a 2-legged walker with balance?".
I would say it is unlikely that one has been built, but certainly not impossible.
For a balancing mechanism you need position sensing, which could be done with a
rotary (distance) counter and a pendulum.

I tried that in my attempts to build a two wheeled robot (as in a bicycle)...but
the problem with rotation sensors (as has been discussed *extensively* before)
is that it drops or gains counts sometimes when it's being rotated slowly.

My post was to clarify the walker question, the suggestion of using the position sensor was just that.

That means that you really have gear up the pendulum's output in order to
spin the rotation sensor quickly - and that gearing slows the swing of the
pendulum to the point of uselessness...unless it's VERY heavy.

I had better luck with a two-coloured pendulum and a light sensor...but
there were many other problems - and I never did get it to work.

The walker problem is not trivial, as you've discovered.

Incidentally, the way most bipeds walk is by leaning forwards so their
Center of gravity is ahead of their feet - and then sticking out a foot
to prevent themselves from falling.  It follows that balancing the robot
may not be the best strategy here.

--
Steve Baker   HomeEmail: <sjbaker1@airmail.net>

That is a correct observation, but no one wants a walker that can't stop and smell the roses--for that you need balance.

Harley Myler
http://macmyler.engr.ucf.edu



Message has 2 Replies:
  Re: Walkers
 
Thanks for the feedback people. I asked the question because I have been working on a walker for around 6 weeks, and was getting a bit discouraged. I have since had some success on the weekend. My walker will now go through it's complete walking (...) (23 years ago, 12-Feb-01, to lugnet.robotics)
  Re: Walkers
 
I don't know much about mechanics or walkers, but what about a gyro device that's more stable than a rotational sensor. Surely someone out there would know how to use one of these to "balance" a walker. Of course this means powering the gyro to spin (...) (23 years ago, 13-Feb-01, to lugnet.robotics)

Message is in Reply To:
  Re: Walkers
 
(...) I tried that in my attempts to build a two wheeled robot (as in a bicycle)...but the problem with rotation sensors (as has been discussed *extensively* before) is that it drops or gains counts sometimes when it's being rotated slowly. That (...) (23 years ago, 9-Feb-01, to lugnet.robotics)

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