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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Thu, 15 Apr 2004 04:47:54 GMT
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Viewed:
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8242 times
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In lugnet.technic, Steve Hassenplug wrote:
> In lugnet.technic, Kevin L. Clague wrote:
> > In lugnet.technic, Steve Hassenplug wrote:
> > > In lugnet.technic, Kevin L. Clague wrote:
> > > > You might want to study this:
> > > >
> > > > http://www.kclague.net/Quad242/index.htm
> > >
> > >
> > > looks good. But slow.
> >
> > Yes, slow, more pressure, or more force. Shall I assume four pistons per leg?
>
>
>
> That's up to you. I'd like to see it move as fast as possible, but I think even
> if we make it as small as possible, it's going to weigh at least 10 pounds. 3
> or 4 pounds will be the RCXs, battey box, Spybot, and motors.
>
> So, what will it take to move that?
Hmmmm.... interesting question.
I don't know much pneumatic theory, but.....
Pressure is in pounds per square inch. So if we know the area of the face of a
piston, and we know the pressure we can determine how many pounds a single
piston can lift.
Force = Pressure * Area
A pneumatic piston face is about a half an inch in diameter. The area then is
pi times diameter, or about 1.6. Four pistons then have the combined area of
6.4.
So the minimal pressure needed is 10 pounds / 6.4 sq inch = 1.5 pounds/square
inch. Unless my math is wrong (and it could be) four large pistons should be
easily able to lift 10 pounds within the upper limit of 32 PSI inherent in LEGO
pneumatics.
One nice thing is that the vertical pistons do not have to *lift* the body,
because the body always stays the same distance off the ground. So the speed at
which legs the legs lift and drop is simply related to the speed at which the
pistons can expand/contract, combined with the resistance provided by the two
switches the piston flips. If the resistance provided by the switches causes a
big slow down in piston expansion, then doubling the pistons will reduce the
expansion time. If the switches don't slow things down much, adding a second
piston won't help much. I'll have to test this.
Pistons expansion/contraction rate depends on inherent resistance and pressure.
The way I control the pneumatics, when multiple pistons are
expanding/contracting at the same time I make sure that all have completed their
change before the next change starts. This means that the slowest pistons
control the rate. This is intentional to make sure that they all stay
coordinated.
I'll try to make sure my leg/hip design does not slow piston
expansion/contraction.
Kevin
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Message has 1 Reply:
 | | Re: SSClagorpion
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| (...) Mark Riley was nice enought to point out the errors in my math. The area of the piston care is pi * r^2 = 0.2 Four times that is 0.8. So the minimal pressure needed is 10 pounds / 0.8 square inches or, 12.5 pounds per square inch. Still well (...) (20 years ago, 15-Apr-04, to lugnet.technic)
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Message is in Reply To:
| | Re: SSClagorpion
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| (...) That's up to you. I'd like to see it move as fast as possible, but I think even if we make it as small as possible, it's going to weigh at least 10 pounds. 3 or 4 pounds will be the RCXs, battey box, Spybot, and motors. So, what will it take (...) (20 years ago, 15-Apr-04, to lugnet.technic)
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