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post #3 of (permalink) Old 10-14-2016, 05:59 PM Thread Starter
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Join Date: Aug 2012
Location: Vermilion Alberta Canada
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Originally Posted by torriem View Post
Looks great, Brian! How are you storing the coverage data? Are you using a GIS database of some kind? Even in its simple form it's at least as functional as the Raven Smartboom, but with a visual display. Even if you consider the cost of a windows tablet to run it on, it is still cheaper than the old raven unit.

This is a normal win32 C# app, right? I wonder how much work it would take to get it to run under Mono on Linux.

Would a GPS refresh rate of 5 Hz be slightly better or does it not matter in practice?

I was wondering what it would take to calculate where the implement is relative to the tractor during turns and so forth. I did some research into trailer path prediction algorithms, but never put anything concrete together.

Though in practice when using the Raven SmartBoom, which has no such turning compensation, it didn't seem to matter nearly as much as I thought it would.
Coverage, using the current fix position from the GPS and for each section am recording where that is. Next fix i'm recording the new position, so now i have 4 points - a quad. So in opengl i start a triangle strip - two triangles make the quad where i just was, and as the section moves forward it keeps adding new fix positions making more. When the section turns off, that group is added to an array of multiple patches. Each section does this. Fix is recorded in UTM WSG84 values - converted from latitude and longitude - so it can easily be converted and put into a shapefile or just saved as a csv. Could program it to simply record the fixes from the antenna location too and you would have all the data, saveable, and in any for you want. The beauty of open source.

The implement to vehicle pulling radius is an algebraic nightmare. I "got around it" by using a delay line of fix positions to emulate the turn radius of a pulled implement that is speed and fix rate calculated. It actually works extremely well. It does make me wonder for a tow between there is no setting in modern GPS for double hitch geometry. Its obvious the pros fudge it too - especially at the distance the fore/aft setting is. The best would be an antenna on the implement and an antenna on the tractor for guidance. It would be stupid accurate and would compensate for drift on hills.

5 hz is buttery smooth and accurate and is all that is required. Have driven down the road at 50 mph and it works flawless. Its not on the property page but i can set the look ahead time, must add to settings yet.

Yes win32 written in C# and Opengl. Haven't come even close to the 2G memory limitation on a 1200 acre field.

Started with 5 sections, but more could easily be added.
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