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[DPRG] RC Car as a general purpose robotics platform???

Subject: [DPRG] RC Car as a general purpose robotics platform???
From: Robert L. Jordan rljordan at airmail.net
Date: Thu Aug 10 07:17:27 CDT 2000

Timothy,

They are fun to play with but my efforts lead me away from them. Reasons below.
Turning radius too wide for my use
Ground speed too high and torque for the additional weight was too low
Speed control was power hungry trying to get the car up to speed.
Center of gravity too high with added robotic stuff.

I went from Servos to Gear head motors with HBridge drive. You can get the right combination for torque and speed, but  often have to build your own platform.

Regards,
Robert L. Jordan

-----Original Message-----
>From:	Timothy Deterly [SMTP:timdet at san.rr.com]
Sent:	Wednesday, August 09, 2000 10:52 PM
To:	dprglist at dprg.org
Subject:	[DPRG] RC Car as a general purpose robotics platform???

Hi,
	I was just wondering what everyone's opinions / experiences are on RC
cars/trucks as robotic platforms.  I have been thinking about buying some
sort of RC truck and ESC for use as a general purpose experimental robotics
platform.  Is this a good idea or am I missing something?  The reason I ask
is because it sounds like a pretty good to me, but I haven't seen many robot
make from them...  I am not really a hardware guy, and I am no longer happy
with servo driven bots...
Any thoughts would be great!

Thanks,
Timothy Deterly
timdet at san.rr.com

-----Original Message-----
>From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org]On Behalf
Of David P. Anderson
Sent: Wednesday, August 09, 2000 12:39 PM
To: dprglist at dprg.org
Subject: [DPRG] Camera Car (was Electronic Speed Control)



Howdy

Seems like we might have enough CameraCars for a competition.

We use an off-the-shelf Traxxas R/C speed control, manufactured
here in Dallas (well, probably really in Taiwan) on our camera car.
This is the speed control that came with the car, which is a Traxxas
"Big Foot" monster truck with the body removed.

We modified the drive train for lower speed/higher torque gearing,
as mentioned by Patrick in his posting.  The camera and transmitter
are driven by a 10 cell pack of AA nicads.  This is mounted underneath
the car to the bottom side of the chassis (lots of ground clearance on
a monster truck) and helps lower the center of gravity a little and
counterbalance the camera/transmitter/antenna.

We also "slammed" the truck by removing the stock wheels and replacing
them with smaller (2 inch?) ones, reducing the high speed somewhat and
getting a bit more torque, to handle the now heavier car.  It will still
go faster than any of us want to drive it, and accelerates much better
with the smaller wheels.

Most of the time we just drive around the house and yard, or the building
here at work, and look for people to interact with.  I have a funny
video tape of pushing trash cans around the lobby, and pushing one down
the stairwell and then running away like a bad little kid.

I have also raced against Mr. Michael Hamilton, who has won national
championships racing normal electric radio controlled cars.  We have
a course laid out in his house as follows.  Start in the living room
in front of the TV, then around through the bedroom to the kitchen,
straight through the kitchen and out the door into the garage, between
the motorcycle and the pickup (watch that kick stand!) around the
pickup (Michael later added a trash can for a "chacane") back through
the kitchen door and hard right from the kitchen back to the living
room.

It's actually very exciting.  The camera image shakes around on the TV,
and because the camera position is so close to the ground it really
appears to be going extremely fast.  A lot of driving skill is required
to maneuver through the tight spaces and still keep the speed up.  We've
knocked the camera off several times and broken 3 different antenna
mountings.

Five laps is one heat.  One of us drives, the other times it with a
stopwatch.  First we had to drive it enough that we stopped running off
the course and hitting things.  Then we really started to race.  We
stayed up 'til 3:00 in the morning one weekend, and Mike was turning
in 15 second laps, amazing!   But I held my own, always within a few
seconds of his times.  I'm not sure his experience really helped that
much in this circumstance.  That's encouraging!

Mike believes that with a different motor and better batteries,
we might be able to turn in 12 second laps, and break the now infamous
"One Minute Barrier.

Mr. Hamilton is the current World Champion Denton Texas Invitational
Indoor CameraCar Grand Prix.   And I'm Number Two.

You might have a similar course layout in your home.  You could also
be a World Champion!


cheers,
dpa


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