Subject:
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Re: Seeking Strategies on Humanoid Robots/Walkers
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 31 Dec 1998 23:33:50 GMT
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Original-From:
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L. M. Lloyd <lee@advfilms.AVOIDSPAMcom>
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Viewed:
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1524 times
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Andrew Phelps wrote:
> Interesting !! Nice to have someone else tackling the problem, I guess if
> your on the Internet your never alone :) That is a good idea about using
> MEL, it should be possible to construct a file, perhaps even standardize a
> format to it and then read it in and send the important bits to the Lego RCX
> using NQC or even the VB control. (I am still hoping for a Java
> solution...)
>
> As far as getting the pieces into Maya I have had fairly decent results in
> measuring and modelling each individual piece in a CAD package and importing
> into Maya
I wish I had the time to do this, but all my modeling time gets taken up by
work.
> such that everything is "too scale" and re-calibrating the Maya
> Co-ordinate system such that 1cm = 1cm in the "Real World"(tm) (I have found
> centimeters to be the most practical units of measurement thus far).. I
> will have to look at whether you can then get rotational data that is to
> scale (I would assume so but a test is always necessary). I import via DXF,
> and then rebuild in NURBS if necessary.
>
> Then, assuming you have all the rot data, it should be possible to build a
> program that will parse though the text file, grab all of the changes,
> figure out which joints they are changing, and then call function
> pre-designed to move those joints (make a function "ROTATE LEFT SHOULDER
> (value)".
My solution on the Maya side of things, is to setup all the gears with a series
of "Driven Keys" so that each gear in turn forces the appropriate movement out
of the surrounding gears. This chain of gears in turn drives (once again through
driven keys) a "motor" object, every 360º of "motor" rotation I have an
expression increment a variable (motorN_rot). In the real world I plan to put a
rotation sensor on each motor and use it to match up full rotations of the motor
with the variable (motorN_rot)
> This function would in turn use the OCX to control Lego motors.
> As previously stated, I will have to work out some conversion between
> rotation and motor revolutions/time. This will likely be difficult.
see above
>
>
> The other problem will be one of timing, getting the program to be in synch
> with Maya's timing mechanism of 30 frames per second. Mabye set the program
> up so it executes x number of actions per minute ? I don't know, I need to
> play harder <G>
Wow, I have been working in SMPTE so long that I never thought about this.
However Maya (at least as of V1.5) has a time setting for milliseconds, seconds,
whatever, so now that I think about it it's not a problem.
> I am somewhat unfamiliar with Ldraw, what specifically is
> the difficulty ? There is a converter from Ldraw to DXF called (not
> suprisingly) DAT2DXF but I have not used it.
Ldraw parts look good on instructions but their dimensions are not too exact,
causing even more slop in an already very sloppy system (Technic).
> If you ever have to re-model
> the little studes on lego pieces, there is an instance plugin in the KPT
> tools that is incredibly useful.
Unfortunately I do not have this tool. How much does it cost? Where can I get
more info on it?
> Hope this helps,
Yeah, it's fantastic to know I'm not the only nut doing this!
--
__________________
L. M. Lloyd
lee@advfilms.com
SGI Animator
ADV Films USA
__________________
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | RE: Seeking Strategies on Humanoid Robots/Walkers
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| L. M. Lloyd said, Unfortunately I do not have this tool. How much does it cost? Where can I get more info on it? This plug-in is in a set of plugins called KPT and they are (gasp) FREE (this is unheard of using an SGI for those of you who aren't (...) (25 years ago, 1-Jan-99, to lugnet.robotics)
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Message is in Reply To:
| | RE: Seeking Strategies on Humanoid Robots/Walkers
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| Interesting !! Nice to have someone else tackling the problem, I guess if your on the Internet your never alone :) That is a good idea about using MEL, it should be possible to construct a file, perhaps even standardize a format to it and then read (...) (25 years ago, 31-Dec-98, to lugnet.robotics)
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