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Subject: 
Re: Walker Balance
Newsgroups: 
lugnet.robotics
Date: 
Mon, 7 May 2001 10:57:02 GMT
Viewed: 
657 times
  
In lugnet.robotics, Andy Gombos writes:

   I have been working on my pneumatic walker for a while and have ran
into a problem.  Looking at all the other walkers out on the internet, I
noticed that all designs use a track system or a tipping system for
shifting weight on top.

I posted a couple of weeks ago a link to my list of Lego Biped on the
Internet (www.geocities.com/technicpuppy). I hope you've had a look at it,
since there are plenty of systems to accomplish a walking biped. Fost
instance, you don't necessarily need to shift the center of gravity if you
use interlocking footprints.

I don't really want to use an ankle shifting
mechanism now, due to the fact that I only have so many motors,

In the same site, you'll find plenty of documentation about Hammerhead, a
mono-engine, ankle-level COG-shifting bot that carries a (big) Technic
battery box. I'm sure it will be able to carry the RCX (it might need some
slight modification). I'm not proposing this solution as best, but rather
point out it can be done.

but I
try tipping the rcx over each leg, and that doesn't work, then I built a
rack system.  It was at least 30 studs long (2 of those really long (16
stud) ones, and a 4 stud one), and the only way I got it to balance was
by having the RCX totally on the outside of the leg.

Have you tried raising the rack, the RCX or both? - this works with biped
of the ankle-level weight-shifting type. By raising the weight, you also
raise the center of gravity, generally reducing the practical
side-to-side-weight-balancing movement.


Anyway, when the
legs move, the balance shifts slightly, and the walker falls.  I need a
new solution for balance.  Would an ankle-shifting mechanism be best? I
think that I am going to run out of motors anyway, so I guess it doesn't
matter how many the system uses.

See above for a reference to a single motor type, but you wouldn't need more
than two in any case. Balance is tricky anyway.

   Right now I have it being able to take one step, but when the leg is
at its fullest extension, the robot tips forward, and balance is lost,
because of the other leg now being behind.  I am stuck at this step, I
can't get the robot to have legs both up and down from this  position:
                     |\
                     | \
                     |  \


It sounds like you could have the walking mechanism nailed down but not
adjusted. Hard to say without further details, but Hammerhead will
definetely fall all over the place unless 4 key parts of its mechanism are
positioned fairly precisely.

But then again, as I say on my site, I know little about all this. Only what
I've learned in the past few months while messing with Lego.



Message is in Reply To:
  Walker Balance
 
I have been working on my pneumatic walker for a while and have ran into a problem. Looking at all the other walkers out on the internet, I noticed that all designs use a track system or a tipping system for shifting weight on top. I don't really (...) (23 years ago, 5-May-01, to lugnet.robotics)

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