[linux-elitists] Introducing Myself

Jason Spence jspence@lightconsulting.com
Wed Jan 7 16:25:38 PST 2004


On Wed, Jan 07, 2004 at 11:05:08AM -0800, Ben Woodard wrote: 

> The problem for me is that I'm not as good at mechanical engineering and
> electronic design but as soon as I get to the software I kick ass.
> Finding something where the electronics and the mechanical engineering
> is already largely done and the programming doesn't leave you hog tied
> and gagged in BASIC is a challenge. Right now I've been sort of looking
> wishfully at
> http://lynxmotion.com/Product.aspx?productID=4&CategoryID=25 but I'm not
> quite ready to plunk down $355 for something that has zero sensors and
> can barely lift 3 oz. The problem overall seems to be that servos are by
> far the easiest and cheapest to control BUT no servo is powerful enough
> to do anything really interesting with. 
> 
> Anybody want to talk robotics with me? Anybody know of any good forums
> for open source robotics?

I don't know of any, but every time I've had to do any kind of
"robotics" stuff I just slapped a microcontroller on a custom PCB and
ran wires and stuff to the prime movers.

I've found it's a lot cheaper and easier to build BIG things instead
of small things, because microservos and miniturized sensors and stuff
are low volume products, and well, supply and demand, you know.

There is an exception: instead of using resistance to vary current to
motors for precision mechanical operations (CD-ROM drives, automotive
applications), I keep seeing more and more step motors [1] being used.
It's such a trend that many microcontrollers actually support the
necessary electronic stuff (pulse width modulation) natively without
the need for a separate controller or driver to do the PWM to the step
motor.  Note that dead floppies are a great place to get dinky little
step motors, and you can make your own to your required sizes in a day
or two if you have access to a machine shop and the necessary raw
materials.  I see very few pure servos used in industrial applications
these days...

On the other hand, I can get really high current relays for like $5;
car batteries and other raw materials are easy to come by from my
local junkyard in Fremont.  Couple those to a standard industrial
control motor and you're in business :)

Hydraulics (for really big-ass applications) from broken equipment are
practically free; the problem most places have is finding some poor
schmuck to haul the 200 lb. ones they don't want away :) Of course,
you need something to do the hauling and big lifters to actually mount
the hydraulics on your project, but you can get access to those at
your local garage (or college, if they have a shop there).

[1] http://www.cs.uiowa.edu/~jones/step/

-- 
 - Jason           Last known location:  1.0 miles northeast of Union City, CA

Have an adequate day.



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