Subject:
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Re: RCX 2.0 -- ideas.
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 16 Feb 1999 19:18:11 GMT
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Viewed:
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1671 times
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lego-robotics@crynwr.com (Ian Sinclair) writes:
> > Another way to do it might be ( - I have not built this, but been = • thinking
> > about it for a while, as I want to use it with a (manual, and possibly
> > later also motor-driven) car transmission of the common sliding-axle
> > type - ) to use rubber bands/springs to make the sliding parts
> > self-centering the way a toggle switch pulls into teh new position
> > once you've pushed beyond the threshold. TLG have done this recently
> > in the Spy Runner, the Cyberslam targets (in 8257, at least), and
> > in 8428/8432 (Turbo Command - rear suspension has 2 heights).
> > One would connect the motor and the actual sliding parts with a slightly
> > flexible arm, e.g. short piece of flex system tube, and have the
> > sliding parts go "from notch to notch".
> > A 2-position switch is trivial; I haven't tried one with more yet.
>
> The use of a spring loaded system using rubber bands or such would be
> a good idea for two position systems. But I can't think how to do it
> for transmissions like my current two that four positions.
>
> I think I'm going to try a motor with a worm gear pushing the lay
> shaft back and forth in my first design.
>
> The second transmission needs something more akin to a clock
> escarpment to lock it's rotating part in each of the four positions.
Hmm, just been thinking about this. You could have a shaft that was
free to move back and forth along it axis. On the end of this you would
have a series of N spokes. Each spoke ends with a free to move wheel (the axis
of the wheel is arranged along the tangent to the spokes ie you pop a wheel on
the end of the spoke, using it as spindle). Arranged around this spoke-wheel
setup would be a cylinder (the wheels on the end of the spokes would rest on
the edge at one end of this cylinder). The end of the cylinder would have a
"corrogated" series of highs and lows at this end; such that, when you turn
the shaft that the spindles and wheels are attached to, the shaft would move
back and forth along it's axis as the wheels roll along the end of the
cylinder.
Assuming you've understood the above explanation ( ;-) ) you could attach a
motor to the shaft and an elastic band or suchlike to the opposite end of shaft
such that the wheels are pushed against the end of the cylinder. When we drive
the motor, we will flick through the N positions. This allows us to be a bit
innacurate with our motor drive since if the power goes out as a wheel going
'up a hill' then the elastic band will pull it down to the centre of the dip;
the same thing happens if we just make it over the hill.
I'm sure this idea could adapted to a linear version which may be easier to
make eg have a single wheel travelling along a rolling surface.
ps. I've never seen any pictures of the arrangements described in previous
articles so forgive me if I've inadvertently re-described them.
Mike
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Message is in Reply To:
 | | Re: RCX 2.0 -- ideas.
|
| (...) The use of a spring loaded system using rubber bands or such would be a good idea for two position systems. But I can't think how to do it for transmissions like my current two that four positions. I think I'm going to try a motor with a worm (...) (25 years ago, 17-Jan-99, to lugnet.robotics)
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