AB curve overlap

Today I had a long curved field to drill that needed to be drilled with a curved side so I used AB curve for the first time. It started out ok ish but as i progressed across the field left to right it got worse at following the curve correctly. It was overlapping a full maize row at worst (750mm). It seems to happen in both directions. I eventually gave up and drove by eye and TBF made a far better job of it (cuttings at the right). Just wondering if I had something wrong or could alter something to help the situation?

Oddly boundary curve following (4 outside rows) is absolutely brilliant and way better than I can do with markers.


Ive seen this issue when running simulation

A small amount I could accept being maize but rows overlapping it isn’t good. I had to shift the line a few times but this the leaves wider gaps where it isn’t doing it. It happens more on the inside of bends as you can see on on the screenshot.

Might be useful to know if the tractor steers accurately along the curve wayline (meaning the target line is off) or if the wayline appears to be correct but the tractor tends to drive off the wayline?

Alan, whereabouts have you mounted your antenna?

Roof. 750mm foreward of the axle. I’m wondering about trying the bonnet. Running at 8K.

I’m sure it was pretty much on the wayline. Boundary curve following was unbelievably good. It kept almost perfect spacings, even on really wavy headlands. Way better than I could do with markers given I’ve got a front hopper to see over.

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Hi Alan
I’ve not tried curve much yet but done a few hundred acres with antenna and brick on roof, which I thought was pretty good.
Moved antenna to front of bonnet and accuracy went up another notch altogether.

Think on the bonnet would be worsening things!
As I found to my expense the other day, what’s hitched behind cuts in ( in my case a feed cart), new tyre required.
The same happens with gps, the antenna holding to the line, but the rest behind has to cut in to follow.
You needing to get in the workshop and make a hydraulic side shift with its own planter mounted antenna and AOG!!!

I’m not sure. My problem was the wayline was basically in the wrong place on an inside curve. For 8K i think bonnet mounting might help but it won’t stop what was happening on my curve I don’t think.


On what pass did you set up A/B line?
As you say first 4 boundary passes near perfect, presumably using contour?
Just thinking aloud… If you set a/b on first pass, but only switched to curve on 5th pass?

I set the AB from the picker window. I did my first pass with it one pass in from the 4 headlands. I didn’t expect the AB curve to match the boundary perfectly, in fact I didn’t want it to. My issue is that the curve wasn’t matching itself pass to pass. Especially on the inside of a curve .

I even recorded another curve to see if that would help but I got the same effect.

in simulation thats what i thought. The line was in the wrong spot

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Yes. I’m sure this is what I was finding. I altered all sorts of things. Even Steering zero point. Interestingly altering steer straight ahead significantly seemed to make pretty much no difference to guidance. This is definitely not what I have been led to believe.

I need to do more testing on my own land with implements I can check overlap with easily.

What I find odd is how AB curve is seemingly quite inaccurate but boundary contour following is hugely impressive on much more challenging curves. I’m guessing two completely different concepts.

I don’t know if it helps but yesterday Greg FARMTEK posted his version of AOG on the Telegram forum. It seems he has modified the curves. I haven’t tried it yet, but would like to hear if it’s better since I’m starting planting corn next week…

Yes. I need to try that version to see what happens.

When you use an ABcurve in the contour menu there is a fonction called “smooth AB curve”
Can someone explain how it work and what the number mean?
The default value seem to be 20 and the lines are like in the first post.
When I set it to 5 or 1 it seem to be more accurate.

Edit: on v4.1.12

To respond to my post,
The default value is 0.
After running in simulation I think there is a problem with the AB curveAB curve . Does it only moves the line perpendicular to the two selected points?


Hi does anybody know if this issue with AB curves has been resolved. :slightly_smiling_face:

No, for now , still overlap … :frowning:

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