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[DPRG] offroad robot exercises -- 11 Nov 06
Subject: [DPRG] offroad robot exercises -- 11 Nov 06
From: David P. Anderson
dpa at io.isem.smu.edu
Date: Thu Nov 2 00:50:06 CST 2006
Howdy
Hi Dave,
This is just a simple 100 foot square, so no GPS is really needed. These
points are provided as an option for robot builders that may need them.
You can probably do just fine with a compass and some wheel encoders,
no GPS required. That's basically how jBot does it.
Howsoever, I'm not following your math.
I use a seismologists' tool called "dlaz" that returns azimuth and angular
distance between two lat/lon points. Here's what I get for the four parking
lot GPS waypoints:
>From point 1 to point 2 in lat/lon is:
32.78228 -096.76082 to 32.78218 -96.76051
which is: 110.99 deg azimuth at 31.02 meters
or 101.77 feet or 1221 inches
>From point 2 to point 3 in lat/lon is:
32.78218 -096.76051 to 32.78191 -096.76061
which is: 197.30 deg azimuth at 31.42 meters
or 103.09 feet or 1237 inches
>From point 3 to point 4 in lat/lon is:
32.78191 -096.76061 to 32.78201 -096.76091
which is: 291.63 deg azimuth at 30.15 meters
or 98.91 feet or 1187 inches
>From point 4 to point 1 in lat/lon is:
32.78201 -096.76091 to 32.78228 -096.76082
which is: 15.66 deg azimuth at 31.16 meters
or 102.23 feet 1227 inches
My GPS readings were all +- 3 feet so that seems like pretty good agreement
with these numbers. It's not an exact square, but for the Borenstein
UMBMark tests it doesn't have to be. I'll go over that in more detail
at the meeting Saturday.
best regards,
dpa
> A rough estimate of degree directions based on GPS coordinates would be :
> 252.12 degrees for 0.0003257 degree measure, ~100 feet? from point 1 to
> point 2
> 159.68 degrees for 0.0002879 from 2 to 3
> 71.57 degrees for 0.0003162 from 3 to 4
> 161.57 degrees for 0.0002846 from 4 to 1
>
> Given the variations from 0.0003257 to 0.0002846 in decimal minute or degree
> measure from GPS readings to estimate 100 feet, can there be any surety of
> degree direction?
>
> This was basic rectangular to polar conversion, but I'm probably neglecting
> the changing measure of degree distance as latitude changes. And also did
> not consider the changes in magnetic North based on position, thinking it's
> about 11 degree difference.
>
> I had hoped to navigate by magnitude and direction (magnetic compass)
> readings, though do not have it finished yet. The compass can be calibrated
> to whatever is defined as North though.
>
> Perhaps there can be another definition of points to navigate, maybe ...
> traffic cones? : )
>
> Dave
>
>
> ----- Original Message -----
> From: "David P. Anderson" <dpa at io.isem.smu.edu>
> To: <dprglist at dprg.org>
> Sent: Wednesday, November 01, 2006 2:18 AM
> Subject: [DPRG] offroad robot exercises -- 11 Nov 06
>
>
> > Howdy
> >
> > For the upcoming DPRG meeting at The Science Place
> > on 11 November 2006, I will be presenting a short
> > program on the the Borenstein UMBMark test and
> > how to use it to calibrate your robot.
> >
> > Thereafter we will take robots to one of two asphalt
> > parking lots on the Fair grounds to run the offroad
> robot exercises for whomever may want test out their
> > robots.
> >
> > Scot Sumner suggested a large parking lot on the north
> > side of the Fairgrounds near the Railroad Museum, which
> > looks ideal for us, and he says is usually empty. Here
> > are some satellite photographs and GPS coordinates for
> > that parking lot.
>
> > <http://geology.heroy.smu.edu/~dpa-www/robots/dprg/11nov06/>
> >
> > best
> > dpa
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