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 Robotics / 18975
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Subject: 
Re: RCX simulator ?
Newsgroups: 
lugnet.robotics
Date: 
Fri, 13 Sep 2002 22:44:54 GMT
Original-From: 
Steve Baker <sjbaker1@airmail.net%Spamcake%>
Reply-To: 
sjbaker1@airmailNOSPAM.net
Viewed: 
1121 times
  
Russ Sprouse wrote:

Wow - can you imagine if the simulator could be hooked up with MLCad and
LDraw?  Then you could build a robot with a complex structure, program it,
and have it run around a virtual world, all rendered with POV-Ray!  Man, who
need reality after that?


Woaaahhhh there - just one moment - that's a *REALLY* big step from where we
are.

OK - so I buy the idea of an RCX simulator.

   * You could write one that emulated the RCX at the Lego Byte-Code level.
     That's really easy - I could do it in a couple of hours...not a problem
     - except that it would only be able to emulate the RCX with it's standard
     firmware.

   * You could write an emulator for the RCX's CPU - and (possibly illegally)
     dump out the contents of the EPROM and the Lego Firmware or LegOS.  Then
     you could even emulate the RCX running LegOS or whatever - and you'd get
     realistic timing for things.

Now, the output of that simulator would be things like motor on and off
commands - and if it's sensor inputs were wiggled with the right timing for
the virtual simulator's clock, you'd get it to react to simulated sensors.

And I buy into the idea of being able to render LDraw/MLCad images in realtime,
possibly with the shafts of the motors being rotated by the RCX simulator at
the correct speeds.

HOWEVER - the *huge* 'gotcha' is emulating the physics of gear trains,
axles, bricks hitting bricks with the correct forces, etc, etc.

That is truly an impossible task.  The very best dynamics systems would
be hard pressed to solve the 'stiff' constraints problems of complex systems
like gear wheel teeth - and for even a few dozen Lego parts, the simulator
would take hours to run.  It would quite literally be easier to build the
real robot.

So, no - you can't do that anytime in the likely future.

What you *could* do would be to tell the 'robot' simulator things like:

    For every revolution of motor A, the robot moves forwards 6 centimeters.
    For every revolution of motor B, the robot turns 27 degrees about the
      point (10,30,4).
    For every centimeter the robot moves forward, rotation sensor B turns
      one 'click'.

...but visualising all the internal motion for an arbitary robot is
extremely difficult.

----------------------------- Steve Baker -------------------------------
Mail : <sjbaker1@airmail.net>   WorkMail: <sjbaker@link.com>
URLs : http://www.sjbaker.org
        http://plib.sf.net http://tuxaqfh.sf.net http://tuxkart.sf.net
        http://prettypoly.sf.net http://freeglut.sf.net
        http://toobular.sf.net   http://lodestone.sf.net



Message has 1 Reply:
  Re: RCX simulator ?
 
hi Steve, (...) I expect that it would cost me at least a few weeks of my spare time, so if you've a few hours of spare time, ... I would be much obliged ;-) cheers, Stef Mientki (22 years ago, 14-Sep-02, to lugnet.robotics)

Message is in Reply To:
  RE: RCX simulator ?
 
Wow - can you imagine if the simulator could be hooked up with MLCad and LDraw? Then you could build a robot with a complex structure, program it, and have it run around a virtual world, all rendered with POV-Ray! Man, who need reality after that? (...) (22 years ago, 13-Sep-02, to lugnet.robotics)

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