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Subject: 
RE: Seeking Strategies on Humanoid Robots/Walkers
Newsgroups: 
lugnet.robotics
Date: 
Thu, 31 Dec 1998 22:32:34 GMT
Original-From: 
Andrew Phelps <amp5315@=AvoidSpam=ritvax.isc.rit.edu>
Viewed: 
1515 times
  
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 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)".  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.

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>  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.  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.  Hope this helps,

Andy
RIT
http://www.rit.edu/~amp5315/

-----Original Message-----
From: L. M. Lloyd [mailto:lee@advfilms.com]
Sent: Thursday, December 31, 1998 4:50 PM
To: Andrew Phelps
Cc: lego-robotics@crynwr.com
Subject: Re: Seeking Strategies on Humanoid Robots/Walkers



I am playing with a similar project in my spare time, I have found that your
first step should probably be to write a MEL script that outputs a text file
with all of your rotational data (this is easier if you are not using IK,
but
can be done with IK). What I am currently working on is trying to get
Technic
parts out of Ldraw and into Maya so that I can build my LEGO creation there,
then animate it doing what I want it to, output a text file (through my MEL
script), and figure out some way to get that to work with the RCX. I would
be
curious to hear how you are looking at doing it.
--
__________________

L. M. Lloyd
lee@advfilms.com
SGI Animator
ADV Films USA

__________________


--
Did you check the web site first?: http://www.crynwr.com/lego-robotics

--
Did you check the web site first?: http://www.crynwr.com/lego-robotics



Message has 1 Reply:
  Re: Seeking Strategies on Humanoid Robots/Walkers
 
(...) I wish I had the time to do this, but all my modeling time gets taken up by work. (...) 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 (...) (25 years ago, 31-Dec-98, to lugnet.robotics)

Message is in Reply To:
  Re: Seeking Strategies on Humanoid Robots/Walkers
 
(...) I am playing with a similar project in my spare time, I have found that your first step should probably be to write a MEL script that outputs a text file with all of your rotational data (this is easier if you are not using IK, but can be done (...) (25 years ago, 31-Dec-98, to lugnet.robotics)

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