Subject:
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New list member
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 23 Jul 1997 19:14:18 GMT
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Original-From:
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Boeren, David C <dboeren@uscommIHATESPAM.com>
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Viewed:
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1256 times
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Just wanted to introduce myself as a new mailing list member. I've been
reading the archives for a while, but my workplace only got the mailer
working
correctly to external locations yesterday.
Anyway, I got my HB a while ago from Digital Microsystems. I did have a
delay for about 4 weeks, but I got mine in the mail about 2-3 days after
he
posted the explaination message about his absence.
My first robot was made from a remote controlled bulldozer from Toys 'R
Us.
I removed all the bulldozer shaped pieces and the blade assembly and was
left with a mobile platform with two differentially driven treads. I
run the motors
of the bulldozer off the HB motor outputs, but they are pretty
current-hungry,
so I leave them on about 25% power and put each motor on its own motor
driver chip (don't know if separate chips helps or not). Currently it
has a pair
of photoresistors and is programmed to arc in the direction with more
light
if the light difference exceeds a threshold value.
At one time I had an IR emitter/detector pair, but it only sensed
objects to
about 1/2 inch. I tried putting in a smaller resister to increase the
range, but
apparently that burned it out. Does anyone know how to get reasonable
range out of IR sensors (6 inches)?
My next project is legs. This is an ongoing kind of thing that I expect
to be
working on a long time. The first cut calls for 4 legs with 3 servos
each. Later
I will go to 6 legs, but 4 is OK for now and saves money. I want to use
a pair
of Mini-SSC 2's to do servo control. I'm having a little trouble
getting these
interfaced to the HB, maybe someone can tell me what I'm doing wrong.
I got the serial source code from the WWW page and disable IC's use of
the
serial port. I have a short (6 inch) RJ-11 cable that goes from the HB
to my
Mini-SSC 2. The Mini-SSC 2 uses a 9-volt battery to power the
electronics and
an R/C style 6v NiCd battery to power the servos. My problem is that if
I
leave the RJ cable plugged in after a short time (a minute or so) the RJ
jack on
the Mini-SSC 2 starts to get really hot, and eventually the plastic
begins to
melt! As far as I know, I'm using the serial ports exactly the way they
are
meant to be used, so what's the problem? Do I need a special sort of
serial
cable? The servo positions OK, as long as I unplug the RJ cable once in
a
while to keep it cool.
My initial goal is just to get something walking, but more generally I
want to
study legged motion and see what tradeoffs different arrangements have.
I
believe that a more capable 3 DOF leg will be better than the typical 2
DOF
"rowboat" style legs since it is more flexible and can hopefully
traverse
terrain better. Additionally, the extra servo enables me to change
stance from
a high stance that climbs better to a lower stance that has higher speed
over
smooth surfaces. Eventually I want an adaptable legged platform which
can
tailor its walking style to the task at hand.
If anyone is interested in talking more about legged locomotion or the
Mini-SSC 2, please email me.
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