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[DPRG] Off Roadbots
Subject: [DPRG] Off Roadbots
From: David P. Anderson
dpa at io.isem.smu.edu
Date: Sun Oct 29 11:29:34 CST 2006
Howdy
Randy wrote:
> Dpa: Do you really try to make your robot drive straight? Or
> have you taught it to steer straight?
It's like your hand on the steering wheel. The car looks like
it is going in a straight line, but you are actually making
small adjustments all the time, based on a vector from the
robot's inertial measurement unit.
However, for the first stages in building an offroad robot,
exercise #1 is just "start here, go over there, and come
back." Just a test of all the basic robot systems. The
more subtle navigation improvements come later with exercise #2.
Exercise #1 is when you find out that a wheel comes off after
50 feet, or the right side of the drive train is binding up
and the robot is pulling sharply to the right, or the battery
connections keep coming loose, or some 16 bit counter overflows
after a few minutes and the robot crashes, or a voltage regulator
overheats and shuts down randomly, or any number of other basic
level problems that will make it very difficult or even
impossible to achieve those more subtle levels of navigation.
So the first exercise is just to turn the robot on an make it
go somewhere (and back). That's enough of an initial challenge,
I think. When I first got jBot to this stage I did a little end-zone
victory dance.
Chris wrote:
> jBot is a very mature design. It is essentially safe by design. I think
> David once said that it did not make sense to build an autonomous robot
> that can move faster than you can follow it.
Actually it was a little more selfish than that. I said I don't want my
robots to be any faster than I am. Also don't want one that is any
heavier than I want to pick up. I think that does prevent, as Chris so
artfully put it, "many problems operationally."
That said, we do have some large, heavy robots in the club, and I think
Chris' advice here is important for machines that could potentially do
damage.
The Austin robot builders had a nifty car key-chain type RF remote that
they could use to stop their large robot instantly. Perhaps they'll
write up for us what they are using and how they made it work.
best regards,
dpa
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