Subject:
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Re: why won't my biped walk?
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Newsgroups:
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lugnet.technic
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Date:
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Sun, 22 Aug 2004 19:16:56 GMT
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Viewed:
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3459 times
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In lugnet.technic, Kevin L. Clague wrote:
> The problem is that you are not truly getting the center of gravity inside the
> footprint of the down foot. The critical part is to get the center of gravity
> past the inside edge of each foot.
>
> This is harder when the inside edge of the foot is not close enough to the
> center line of the bot. Your feet might be too far apart. Try to go for zero
> or one studs between feet instead of two.
I'll try that. Though if it works, I may still be baffled as to why. What is
it that causes the CG to move over the down foot at all? At the start of a walk
cycle (when we go from both feet flat to one foot lifting), you have one foot
lifting up -- the bot naturally wants to tilt in that direction. What makes it
tilt the opposite way, over the supporting foot?
Maybe it's some sort of timing issue, where you need to start the tilting of the
feet before the foot starts to lift. I can imagine ways to do that, but they're
complex, and I've seen pictures of simple walkers here -- unless they're doing
some trick I'm missing, I don't see how they could be doing something like that.
> I also suggest that you walk your walker on a hard surface, instead of running
> it on a cloth placemat. Soft surfaces make it harder to drive the inside edge
> of the foot so it has leverage.
Yes, good point, though the placemat was just to give it a good contrasty
background for the photos. But come to think of it, my regular work/test
surface is a padded card table, which is rather soft too. I'll be sure to keep
something hard around for testing.
Thanks,
- Joe
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Message has 1 Reply:
 | | Re: why won't my biped walk?
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| (...) OK, so I think I know why it won't walk. Right now, the rotation axis of the ankle is on the outer edge of the foot. This means that when the center post lifts the foot, the inside edge of the foot lifts, while the outside edge of the foot (...) (20 years ago, 22-Aug-04, to lugnet.technic)
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Message is in Reply To:
| | Re: why won't my biped walk?
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| (...) Good explanations so far. Here are some additions. The problem is that you are not truly getting the center of gravity inside the footprint of the down foot. The critical part is to get the center of gravity past the inside edge of each foot. (...) (20 years ago, 22-Aug-04, to lugnet.technic)
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