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Subject: 
Re: How many people signed up for the NXT Developer's Program?
Newsgroups: 
lugnet.robotics
Date: 
Wed, 18 Jan 2006 21:24:53 GMT
Original-From: 
Mr S <SZINN_THE1@YAHOOspamless.COM>
Viewed: 
1788 times
  
John,

The reason I asked is that to get a Lego robot that is
moving enough to even use GPS (read moving more than 5
yards, and outside no less) it will take a special
build. Your *average* differential drive/steer robot
with castor is not likely to do well on grass etc.
I've followed the information about RoboMagellan
closely, as well as other contests of similar design.
I'm trying to imagine a Lego robot that is competing
in the same arena as R/C monster truck based robots...
I hoped you had some secret inside,
have-to-kill-you-if-I-told-you information on building
such a beasty of a robot with Lego.



--- John Brost <john.brost@gmail.com> wrote:

In lugnet.robotics, Mr S <szinn_the1@yahoo.com>
wrote:
--- John Brost <john.brost@gmail.com> wrote:
The first thing I thougth of when I heard of the
NXT's bluetooth capability was
getting it to recieve GPS data from my bluetooth • GPS
receiver.  Obvious NeXT
step... a GPS guided LEGO rover.

John,
Seeing that GPS accuracy is on the order of • several
yards (optimistically speaking) what LEGO robot • wouuld
you build that could make good use of GPS, and how
would it use GPS?

Cheers

S

I have a great deal of experience with GPS. The
accuracy you mention is indeed
correct (the GPS I'm looking at right now is specd
at 5 meters horizontal
accuracy).  However, when you look at
second-by-second accuracy, it is much
better.  A great deal of the error in many GPS
receivers is caused by drift,
which is how much the reported position of a
stationary object moves over time,
usually over the course of several hours.  When
mobile, the drift isn't so much
of a problem, unless you are trying to drive in the
same circle for hours on
end.  The GPS unit I'm specifically thinking about
using is one of the better
ones for this sort of thing, and given a clear view
of the sky, I think it would
do okay.  I've been impressed with its performance
so far in other applications.
I could even do a running average on the reported
coordinates to clean up any
errors.  Your concerns are indeed valid, but my
experience and intuition tell me
it can be done.

Obviously I'm not going to have something that is
highly accurate, but I am
pretty confident that I could get something to
follow a course within 3 feet or
so.

As for a good use for such a robot, well I never
said I had a good use for it,
besides the fact that I think it would be cool to
do! :)  After all, why do
people climb Mt. Everest?  Because it is there.

Maybe navigating autonomously to pre-programmed
points, sort of like outdoor
line following without the line.  If I got really
ambitious, I did find this
event called Robo-Magellen, which appears to be an
autonomous outdoor robot
competition similar to a mini-DARPA Grand Challenge.

http://www.robothon.org/robothon/challenge.php

Could be interesting, but it would need more than
just a GPS for guidance, maybe
the NXT's ultrasonic detector for obstacle
avoidance.

John




Message has 2 Replies:
  Re: How many people signed up for the NXT Developer's Program?
 
(...) How about a robot like this: (URL) (18 years ago, 19-Jan-06, to lugnet.robotics)
  Re: How many people signed up for the NXT Developer's Program?
 
In lugnet.robotics, Mr S <szinn_the1@yahoo.com> wrote: -snip- Your *average* differential drive/steer robot (...) True enough. I never even considered that type of setup because I didn't think it would work too well. However, a 2wd or 4wd rack & (...) (18 years ago, 19-Jan-06, to lugnet.robotics)

Message is in Reply To:
  Re: How many people signed up for the NXT Developer's Program?
 
(...) I have a great deal of experience with GPS. The accuracy you mention is indeed correct (the GPS I'm looking at right now is specd at 5 meters horizontal accuracy). However, when you look at second-by-second accuracy, it is much better. A great (...) (18 years ago, 18-Jan-06, to lugnet.robotics)

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