Subject:
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Re: ROBOLAB - RCX simulator?
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 29 Apr 2005 18:19:53 GMT
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Original-From:
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dan miller <DANBMIL99@YAHOO.ihatespamCOM>
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Viewed:
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1097 times
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--- danny staple <orionrobots@gmail.com> wrote:
>
> If you were a little sneaky, you could probably design some of the
> basics with LDraw, and then use a Perl script or something to convert
> it...
>
> That is what I would attempt to do.
> Orion
If you search back to the beginning of the original thread on simulation,
that was more or less my original idea. But someone pointed out that LDraw
files dont really contain the information about how pieces actually connect
to each other, which is really the critical information you need. So there
needs to be another step, either automatically derived from LDraw (here^s a
rivet, so this must be a hinge linkage..), or maybe you need another input
phase, where the designer specfies how connected pieces behave -- or some
hybrid of the two approaches.
The other problem, which helpful and knowledgeable folks have alerted me to,
is that ODE (Open Dynamics Engine), which is what Gazebo (the open-source
robotic simulator I was thinking of starting with) is based on, may simply
not be powerful or flexible enough to handle the sorts of interconnections
that you can do with Lego. For instance, it doesnt have any way of dealing
with gears.
My hunch right now is that to be done right this project would need a more
or less from-scratch physics engine, tailored to the specific issues of Lego
design. I think something like MLcad or LeoCad will be useful as a first
pass on the GUI, but again some serious customization will be necessary, and
a new or extended object format will need to be designed that includes all
the stuff necessary for the dynamics. All of which leads me to conclude
that it is a bigger project than I originally thought, probably on the order
of a man year or two to get to something useful enough for more than just a
few curious enthusiasts to care aboout.
I^m still game to work on this, but probably not unless I get a core team of
two or three programmers with 3D &/or simulation experience to commit to
collaborating on the project (not necessarily full time, but at some
reasonable level of contribution.) I think would set it up as an
open-source thing on Sourceforge.
-dan
> --
> http://orionrobots.co.uk - Build Robots
>
> On 4/29/05, dan miller <lego-robotics@crynwr.com> wrote:
> > I think there is some sort of simulator for Brickos, which basically
> > involves compiling for the native processor rather than the RCX.
> >
> > But the issue isnt language -- its what do you use for simulating input • and
> > output? The one I am referring to, I think you have to write C • routines, so
> > its really just for debugging very low-level code.
> >
> > If you are talking about the kind of simulator I was mentioning -- full • 3D
> > graphics, physics, etc -- that emphatically does not exist, and will • require
> > alot of work to build. I think it is doable though.
> >
> > There is one example I know of simulating a real lego robot, its called
> > webots, and it is a commercial package. They have a simulator for a • simple
> > line-following rover. I am not clear on how much work it would be to
> > simulate other lego bots, but I get the impression its not really
> > lego-centric. You would have to design all the Lego features by hand, • ie
> > figure out measurements, etc., and I doubt that a good majority of the
> > things you could build would be possible to simulate.
> >
> >
> > --- danny staple <orionrobots@gmail.com> wrote:
> > >
> > > It would be nice with any of the languages - maybe a small RCX
> > > bytecode simulator, that came with a few basic configurations of buggy
> > > or arm etc - these having predefined physical qualities. It depends
> > > how much you would need to simulate though - if you wanted to simply
> > > step through and see what motors were turning when - then no physical
> > > simulator would be required.
> > >
> > > I find myself thinking of a more complex version of the Lego
> > > stormrunner game as a future model for simulation.
> > >
> > > Orion
> > > --
> > > http://orionrobots.co.uk - Build Robots
>
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Message has 1 Reply:
 | | Re: ROBOLAB - RCX simulator?
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| (...) <SNIPPAGE> (...) Well, I might be able to put in some time building a Blender plugin that could assist with this, but not enough to classify as a core developer. between work, kids and such, I don't get much LEGO time as it is. (20 years ago, 29-Apr-05, to lugnet.robotics)
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