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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Mon, 10 May 2004 16:13:43 GMT
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Viewed:
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16847 times
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In lugnet.technic, Eric Sophie wrote:
> In lugnet.technic, Kevin L. Clague wrote:
> > In lugnet.technic, Eric Sophie wrote:
> > > In lugnet.technic, Steve Hassenplug wrote:
> >
> >
> > > Where do we stand with our beloved, yet silly named project?
> >
> > Hey, who says out project name is silly?!?!? That sounds like something
> > Courtney would say!
>
> Ha Ha! I got Tim in trouble, lol!
Isn't saying is name *always* in vain? LOL!
>
> > Anyway.....
> >
> > I've got 8 legs built, and six framed together to get an idea of dimensions.
>
> Oh there's my baby now! Growing.
> ok, one thing. The body. I gotta teach ya.
> The quick fit to test the feel is cool.
> However the real deal, well, we'll guild that lilly.
>
> The central area of the body can or will feature the Compressor suites and other
> controls. The bedding of these components will serve to bind the other leg truss
> elements towards the central frame.
Right. I agree totally. As I said in a previous post, I'm starting over. What
I learned is that the locking leg works, and that I need to reconsider what it
takes to make it stay upright based on the body shape, the leg shape, length
*and* it's inherit strength. The legs will be much more vertical that the ones
so far, decreasing the leverage when weight bearing, and easing the forces on
the lock mechanism.
I'm going to start with the compressor. Steve, I'm going to make the compressor
using RC Racer motors. They provide the best power for compressing the air.
This means that we'll need a battery box or two. If we want the RCX to control
the motors, then we'll need a motor and electrical polarity reversor(s).
I'm going to try making a compressor out of two pistons and four check valves
from the old LEGO pneuatic single port piston setup. This will give us two
pumping actions per piston per complete rotation. The pumping actions are 180
degrees out of phase. Using two pistons, offset by 90 degrees, we get four
compressions per rotation. This will make it more compact.
>
> The cross bracing and binding of the central body components to the exisiting
> leg structures will layer themselves together, forming the needed structural
> extensions needed for the required rigidity. Once they are bonded slowly and
> carefully.
I agree. It needs to be integrated from the inside out.
When studying pictures of scorpions, I realized that the hips are packed
together with nothing in between, and that the legs spread out giving it
stability. I'm going to work towards that kind of design. The front legs are
shorter, and the back legs are longer. The packed hips make up about half the
torso, and the back legs get long and lead backwards before you get to the foot.
I want to try to mimic this in SSClagorpion. On the longer legs, the
articulations will not be at the hips, but further down the leg closer to the
foot. Then front legs might have the articulation at the hip.
This means I get to build truss structures coming out of the body, and then have
articulation. I like it. Never done it before. For me, building out of LEGO
is about learning. I like to stretch myself on each new project. In the recent
past, I'm mostly stretched myself on pneumatic circuit design. This times it is
going to be about my least favorite class in college: "stresses and strains".
I will consider sideways walking as still in and forget about part count right
now.
So, pack together a spybot, two RCX's, a compressor, pneumatic multiplexors and
their controlling motors, and battery box(es) and polarity reversors and their
motor into the torso. OK......
I also need to make the batteries easily replacable.
I vote I build a high pressure cutoff switch into the compressor. I can provide
an electrical polarity reversor for manual (i.e. human) off/on. This means the
compressors are not controlled by the RCX. One less thing for them to worry
about.
On the topic of the pneumatic "stop/go" switch.....
If we have a pneumatic on/off switch between the compressors and the rest of the
pneumatic circuit, then when we flip off the pressure, we have no idea which of
the walking states we're in, or possibly we're transitioning from one state to
the next. If we leave the beast on for 10 minutes, the pressure in the legs
will drop due to leakage. The compressor cannot help with this leakage, because
it is isolated from the rest of the circuitry. We run the risk of falling down.
I propose that our on/off switch(es?) be placed in circuit in a way that stops
the pneumatic state machine from transition to the next state. This way when
the pressure drops due to leakage, the compressor will kick in and bring the
pressure back up. With this, we introduce the ability to add a hold to any
state.
The question is, which of the states do we want to be able to hold? There are
two points in the walking sequence where all 8 feet are down. I vote we be able
to stop in both of these states. We have the stop/go motor control four
switches that can stop pressure at two points in the circuit.
When we shut everything off, the beast's legs will be locked into place
mechanically, so it should be stable even with all power off, and startup is
simple. This means that SSClagorpion will be able to sleep standing up.
If there are other "hold" points needed in the circuit, we can add those also.
In theory we could hold in every state, but I'm not sure we need it.
Given the above, I guess I have *a lot* to build. :^)
Kevin
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Message has 2 Replies:
 | | Re: SSClagorpion
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| (...) I don't think we need to worry TOO much about easing forces on the lock. My testing shows it works quite well. But there are many stresses on other parts as the legs get longer, and more angled, so moving them in is not a bad idea. (...) I (...) (21 years ago, 10-May-04, to lugnet.technic)
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Message is in Reply To:
| | Re: SSClagorpion
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| (...) Ha Ha! I got Tim in trouble, lol! (...) Oh there's my baby now! Growing. ok, one thing. The body. I gotta teach ya. The quick fit to test the feel is cool. However the real deal, well, we'll guild that lilly. The central area of the body can (...) (21 years ago, 10-May-04, to lugnet.technic)
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