Subject:
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Re: Suspension for supercar sized Hummer? - also motor options
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 16 Oct 2001 23:57:22 GMT
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Original-From:
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Bruce Boyes <[bboyes@systronix.com]ihatespam[]>
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Viewed:
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720 times
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At 21:46 10/16/2001 GMT, Thomas (T. J.) Avery wrote:
> I'm not sure if it will be easy to get 2.5" of ground clearance given the
> wheels you will be using. You might be better off using the "power puller"
> wheels:
> Power Puller: http://guide.lugnet.com/set/8457
> 4x4 Off Roader: http://guide.lugnet.com/set/8466
> They're much larger in diameter.
>
> This may or may not help, but here are a few things I've built:
> http://www.texbrick.com/ideas/vehicles/
> http://www.brickshelf.com/cgi-bin/gallery.cgi?f=5805
>
> There are many others who have tackled the "independent suspension with
> drive" problem so hopefully you'll get more responses. I've cross-posted to
> lugnet.robotics because there are many people there who might be able to
> help (but they may not see this on .technic).
I'm in the same boat and will toss in a couple of more questions. I'm
leaning towards the 8466 4WD kit but haven't bought one and so don't know
what it's like up close.
I have the 8465 which looked worthwhile to get various suspension and
steering bits. I've also ordered extra shocks, etc.
Here's the real issue: What's the best way to transfer power to four
wheels, assuming maximum traction and performance is what you want? I'm
using 9.6V NiMH R/C model battery packs and could power with two or more if
needed.
1) One drive motor and dual differentials and transfer case. I have a
simple model of this built up on the 4WD X-Track 8279 which lacks suspension
2) separate motors for each end with U-joints and drive shafts or flex
drives (from Znap sets), perhaps a differential at each end
3) the ultimate perhaps - separate motors for each wheel, with monitoring
of each axle for rotation and stalling, using a rotation sensor. This
feedback would assist with load sharing too. Could use flex drives or
U-joints. You need four motor outputs but we are using our JCX prototypes
and have that many.
On a related theme, it would seem relatively easy to make all four
(powered) wheels steer since you have to solve that problem for the front
end anyway.
To really get carried away (Purists please don't read this), it's also
possible to use a non-Technic geared motor and a separate H bridge to drive
them, using just the Technic suspension and structure components. One of my
students just worked out the way to do this using a stock Jameco geared
motor with a Technic axle coupling and it is powerful. It is a bit heavy
though, about 2X the bulk and weight of the Technic geared motors. We
haven't worked out how to mechanically mount the motor case to the Lego
studs. This seems interesting enough that we may make a JSimm board which
has 2 or 4 of the H bridges installed, along with load monitoring feedback,
and offer this as a product.
I'd love to hear from anyone who's contemplated or done motor per wheel
drive and or used the 8466 kit with motor(s) added.
Bruce
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