Re: On Topic Electronics club?

I have looked into Lego, but not used them at work.

They have a very small and simple microprocessor on-board.
Only big enough for pure-embedded applications.
Not really big enough to host a useful operating system.
There are several languages driving cross-compilers to
program the brick.  Many of which can be LINUX
hosted.   I think I would start with RobotC.

There are also many tools to control the robot from a PC.
They can speak by USB and BlueTooth.
USB is faster for short commands, low latency.
There is a significant latency on the BlueTooth turn-around.
Like 60ms or something.
Hence, USB for control loops with the PC as controller.
BlueTooth for larger amounts of data (cameras) and less-frequent commands.
  (control loops, if any, implemented on device)

LEGO published a low-level brick API (runs on PCs).
I would try to start there if possible.
A bit painful, but it is the only interface that gave me confidence
that I MIGHT be able to operate a control loop from the PC with
something approaching the max theoritical command rate.
(Perhaps a KHz or two)

I'm too old to have used them...  but they are a great tool, being used in
most mechanical engineering programs around the country.

You can give them the simple-minded commands that most people will use.
You can also program them to run real closed-loop control.
They have independant sensors on most servos.

There are toolkits to use them with expensive packages like LabView
to perform REAL work in a REAL science/engineering lab.
Great for basic tasks like changing a filter, putting a mirror
in an optical path.  Perhaps even use them as a servo/(sensor)
on a seperate hi-quality mechanical device...  like have
them turn the wheel on a mechanical hi-q turntable.
(Like where +- 1 degree on the wheel is +- 1 arc-sec on the table)

            aaron


> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Ed Heron
> Sent: Monday, February 11, 2008 3:57 PM
> To: New Mexico Linux Users Group Mail List
> Subject: Re: [NMLUG] On Topic Electronics club?
> 
> From: "J. Marsden DeLapp" <[email protected]>
> Sent: Monday, February 11, 2008 1:57 PM
> 
> > I would be interested in a club / discussion group that deals with 
> > hardware hacking as long as the hardware is
> > running/controlled by Gnu/Linux and/or other free/open 
> source software.
> 
>   Check out http://tldp.org/HOWTO/Lego/index.html for info on 
> the Lego RCX. 
> It's a Robotic Control System for Lego.  Has the advantage or 
> being a place 
> to begin playing with simple robotics and an already existing 
> platform, so 
> ramp-up time could be minimal...
> 
>   I'm not clear on whether you can actually put an embedded 
> form of Linux on 
> the brick or just control it from Linux...

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