Subject:
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Re: SSClagorpion
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 20 Apr 2004 22:00:17 GMT
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Viewed:
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9720 times
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In lugnet.technic, Steve Hassenplug wrote:
<snip>
> > > If I understand this correctly, when he puts his other four feet down, and
> > > senses one foot is off the table, he must continue walking forward, raising four
> > > feet from the table, and leaving him standing on three feet, including NO front
> > > feet.
> > >
> > > That makes me think we'll have to consider weight distribution, and how it will
> > > balance on three feet.
> >
> > You are right, he needs to balance on the three feet that are further back, but
> > it will not have to walk forward. It can walk backwards.
>
>
> Well, it will walk forward enough to lift the other four feet off the ground,
> before it starts backward, again.
Nope. The sequence is:
1. All feet down.
2. Lift one foot group
3. Sweep legs
4. put feet down
5. Lift other foot group
6. Sweep legs
So it does not need to walk forward to lift the feet.
>
> I'm going to have to look at the walking logic more to understand why it can't
> start walking backward, while all the feet are on the ground.
The description is here:
http://www.kclague.net/Quad242/quad242-design.jpg
Piston A is a timing only piston (i.e. it is not part of any leg assembly).
A' and A'' are weight bearing leg pistons that simply mimic A.
Piston B is a timing only piston.
B' and B'' are weight bearing leg pistons that simply mimic B.
C,D,E, and F are hip pistons that force the legs to sweep.
A' is paired with C
A'' is paired with D
B' is paired with E
B'' is paired with F
A contract = B' & B'' & ~C & ~D & E & F
A expand = C & D & ~E & ~F
A' = A
A'' = A
B contract = A' & A'' & C & D & ~E & ~F
B expand = C & D & ~E & ~F
B' = B
B'' = B
C expand = D expand = E contract = F contract =
A' & A''
C contract = D contract = E expand = F expand =
B' & B''
To flip from forward to reverse involves swapping the inputs to C, and the
outputs from F.
The feet go to the ground at synhronization points 0 and 3. Those depend on B',
B'' and A', A'' respectfully. Throwing it into reverse at this time would try
to make the feet sweep while the feet are on the ground.
At synchronization points S1 and S4, two of the four feet are on the ground, and
C, D, E, and F will be trying to change, so this is the fine time to flip it
from forward to reverse or visa versa.
At syncrhonization points S2 and S5, you are depending on the fact that C, D, E
and F have stabilized to expand A or B respectively. Now is not a great time to
reverse polarities because you have a potential race between polarity reversal
and A or B completing expansion, so the results are hit or miss.
>
> So, we'll need to make sure the center of gravity is closer to the third set of
> legs, and it CAN'T be in front of the second set.
>
> I hope Eric's listening. :)
Is he back yet?
>
> Steve
Kevin
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Message has 3 Replies:
 | | Re: SSClagorpion
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| In lugnet.technic, Kevin L. Clague wrote: <snip> (...) Oops: B expand = ~C & ~D & E & F (...) Kevin (20 years ago, 21-Apr-04, to lugnet.technic)
| | | Re: SSClagorpion
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| (...) I keep thinking about a rotary type walker, where the feet more or less go in a circle and the body is always moving forward. Please forgive me. :) So, when it lifts one leg group, and someone switches it into reverse, will it put those legs (...) (20 years ago, 21-Apr-04, to lugnet.technic)
| | | Re: SSClagorpion
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| (...) I'm back I'm back. What can I do? I want to build something. I'm gonna make a concept moc moc up. Pun intended. e (20 years ago, 21-Apr-04, to lugnet.technic)
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Message is in Reply To:
| | Re: SSClagorpion
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| (...) There are a couple ways that come to mind. If you don't want to know the details, skip ahead... We want to know when the leg is extended, and the foot is not touching the ground. There will be four possible states: 1) Leg up, foot not touching (...) (20 years ago, 20-Apr-04, to lugnet.technic)
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