Subject:
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Re: The Clague - Sophie Project
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Newsgroups:
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lugnet.technic
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Date:
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Wed, 14 Apr 2004 22:45:26 GMT
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Viewed:
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6020 times
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In lugnet.technic, Mark Bellis wrote:
> In lugnet.technic, Kevin L. Clague wrote:
> > In lugnet.technic, Mark Bellis wrote:
> > > I have a plan in mind for a sidewinding snake. It would be composed of 32
> > > similar segments, each connected to the next by a pivot with two opposing
> > > cylinders driving it. The idea is that there is a main extended flip-flop of 8
> > > variables, where each variable of the flip-flop controls every eighth segment,
> > > so that four segments do the same thing. The pivots move by +/- 45 degrees
> > > relative to the next segment.
> > >
> > > The snake begins in an M shape, with 'feet' on the underside of the five
> > > straight segments in one direction only being on the ground, the other feet
> > > being retracted. Feet are only extended when the segment is in the correct
> > > orientation and are retracted at other times. They may be driven by small
> > > cylinders and don't need to be monitored by switches.
> > >
> > > It is possible that the opposing cylinder sets will be composed of four
> > > cylinders - two set of two cylinders in series, such that when one pair are
> > > extended and the other retracted, the two segments will line up straight,
> > > However, this would need 128 cylinders and may extend the flip-flop to 16
> > > variables, requiring 16 lots of several switches!
> > >
> > > Once the snake will sidewind, the next challenge is to get its head to keep
> > > pointing the same way all the time. I think a car tyre air compressor (set to
> > > 25-30psi) is a prerequisite!
> > >
> > > This'll keep Kevin busy for weeks! :-)
> >
> > I was presuming that I'd have 6-8 segments, where each segment (except the last)
> > has two pistons, and four switches (at least). Given how large inchworm is,
> > getting any larger would make it difficult to transport.
> >
> > Inchworm took me about four hours to come up with a good geometry for a segment,
> > then about an hour to replicate all the segments, and an hour to hook up (if
> > this were electronics I'd say wired up, but since this is pneumatics should I
> > say hosed up?) It took me years to figure out how to do the circuit analysis
> > that would let me know for sure it would work on paper before I built it.
> >
> > I have to sort out one primary question: Can I get both pistons onto one
> > segment *and* make the connection to the next segment a single joint with two
> > degrees of freedom, or will I have to have two joints?
> >
> > The circuitry design is a piece of cake.
>
> A sidewinding snake I saw on TV was in an M shape, with effectively two feet on
> the ground all the time.
>
> You'll have to synchronise four segments for each advancement of the 16-stage
> flip-flop! This is gonna bankrupt you and outstock TLC of excavators! :-)
Well 16 segments means 32 pistons and 64 switches. I have that much easily, but
the bulk of it is in-model in inchworm, quad242 and PHD.
PHD is too expensive to keep around once I get it all hosed together and
working. It has 48 switches in polarity reversors alone.
>
> I suggest that the two segments and a beam all pivot on one axle and that a pair
> of cylinders from each segment push the beam. That way the beam can be turned
> either way, still allowing the two segments to line up straight.
>
> Mark
Kevin
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Message is in Reply To:
 | | Re: The Clague - Sophie Project
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| (...) A sidewinding snake I saw on TV was in an M shape, with effectively two feet on the ground all the time. You'll have to synchronise four segments for each advancement of the 16-stage flip-flop! This is gonna bankrupt you and outstock TLC of (...) (21 years ago, 13-Apr-04, to lugnet.technic)
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