DPRG
DPRG List  



[DPRG] offroad robot exercises -- 11 Nov 06

Subject: [DPRG] offroad robot exercises -- 11 Nov 06
From: David Peterson robodave1 at tx.rr.com
Date: Thu Nov 2 01:30:21 CST 2006

Yes, that was my point, my math was "graph paper" math, standard rectangular 
to polar, not taking into account changing distance meaning of degree 
measure at different latitudes. What I really hoped to clarify was the 
correct degree direction measure. Because my distance estimate was off, I'm 
sure the degree "heading" calculation was off as well. And I had not looked 
for a formula yet to calculate the appropriate direction (heading, bearing) 
based on a set of GPS points. It would seem  that each new heading should be 
90 degrees from the last, but is there a formula for calculating the initial 
direction? I don't have a tool like "dlaz" (guessing it is a Linux program) 
It is interesting that the headings below are not 90 degrees from each 
other. Pretty close though. Should we use the 110.99 to 197.30 to 291.63 to 
15.66 degree headings? (Assuming of course I actually have a robot respond 
to compass headings apprpriately).

Dave

----- Original Message ----- 
From: "David P. Anderson" <dpa at io.isem.smu.edu>
To: "Comcast email" <robodave1 at comcast.net>
Cc: <dprglist at dprg.org>
Sent: Thursday, November 02, 2006 12:50 AM
Subject: Re: [DPRG] offroad robot exercises -- 11 Nov 06


> 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
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.409 / Virus Database: 268.13.21/511 - Release Date: 11/1/2006
> 


More information about the DPRG mailing list