Some guidance on guidance

It was not an easy topic to explain, but many people have been asking about it. The original v4 autosteer was relatively simple, but the pivot did not follow the line on any sort of curve and any side draft was not corrected.

So that is what I have been working a lot on. Probably one of the hardest things to get consistently right, where one day it works, next day it seems to not as well. A different strategy now on overcoming some of the original challenges and that is explained in the video. I look forward to the discussion.

Of note, youTube no longer does auto subtitles in other languages so I will have to figure out something else to add subtitles.


Looks great!

I think it is the right step also to get the machine on the line. This is the next point :see_no_evil:.

But I think this would be very important. I am sure it is very hard to do this ;-), but in case of a rigid fixed machine it seems to be possible.

Thanks a lot for your great work!


Really Great Video!
@Brian Is the eP Offset topic in Version 4.3.10 already included, or a will it be a new Feature in the future. I am very intressted into this topic, because i mainly drive Ab curves.
@stofficl you mean like drawn on the picture?
An additional Distance Air eT or maybe replace eP because the Tool is important to follow the line. For rigid Tools it should be possible. For not rigid Tools i guess the Problem is in the beginning when you dont know the exact Position, but after a while or some meters it should follow mathematicly,because its towed.
Very intressting topic.

@Bada absolutely!!! Thanks for the drawing!

In the last 5 years I drove with my Trimble-guided tractor I learnd the following:

  1. In case of eg seeding it is absolutly necassery that the Point eT follows the line. I agree that it is very hard to calculate for not rigid fixed tools. For rigid fixed tools I think it would be able to calculate.

  2. In case of eg a fixed sprayer it is important that the point eP is chosen. Because in this case we want to drive at the tramline.

I think the big advantage of using Point eT is that it replaces the side hill draft completly. I think in this case it is not needed any more.

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Excellent video @BrianTee_Admin !!

Very interesting, and looks like you have been extremely busy… Also looks like you have made huge progress on getting on top of the cross track / draft error issue, which is very exciting!

I cant wait for this new version to test!

Thanks Brian!! :slight_smile:


I know the video was already over 30 minutes, but yes. We know where the pivot is as, as well as where the tool “should” be. Even though the tractor will be showing straight forward, the curvature will help.

I am unsure until testing exactly what the real world effect is of a fused heading will be on this method, but it seemed to work pretty well “forcing” the heading error to try and compensate for the steer distance alone.

I’ll extend the pivot point back to a rigid tool position and give it a try, got really late last night so ran out time.

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I am glad to hear this! :+1::+1::+1:

I know: Sitting and coding for hours over hours feels like a few minutes :rofl:

Are you sure that Trimble screen actually steered the implement to the curved wayline? I thought Trimble did that only with their implement steering option (with one antenna at the implement?)?

The only single antenna steering setup that I know steering the implement to follow a curved wayline is the Fendt Varioguide. Fendt does it even with trailed implements, not only with rigid implements. Must be extremely complicated to make it steer like that. All other brands that I have tried or seen working, steer the tractor pivot point to follow the curved wayline.

Fendt nowadays even allows the operator to select between pivot point steering and implement point steering. A really nice feature but I think “pivot point based steering” is already quite sufficient. Any implement would anyway work best if tight turns are avoided and if tight turns are avoided, overlaps and skips appear small even if the implement is not following the wayline but the pivot point is.

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Yes, I am almost sure Trimble steers the implement to the line. I have got a lot of curved fields and it works fine.

But you’re right that there is an additional option with an antenna on the implement and a moving frame. I don’t have this option.

Pivot point steering is perhaps enough for fields on flat land but not for hilly regions!

How does the trimble system know where the implement is? We have a pro700 in the 4wd, it certainly does not do anything but try to keep the tractor on the line. Curved lines are a bit of disaster with it.

Unless it has an implement antenna, must be calculating it’s path.

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@BrianTee_Admin I don’t know exactly. And I don’t know if it also works fine with trailed implements too. In my case I only can speak about rigidly fixed machines. And in this case I think it is relatively easy…
(We don‘t care about moving of the lower links)

Perhaps too much off topic for this thread but how do you know if this Trimble keeps the tractor on the curved wayline or the implement? Up to some decent curves one would not notice from the coverage map on the screen, neither from the true coverage on the field. The implement would cut a bit corners but would do it about the same on the next run.

Create an imaginary trailed implement with wheels very far behind the tractor. On a relatively tight curve you would see the tractor driving metres off the wayline while the implement would follow the wayline (approximately).

I would call all related calculations very complex. I consider the current AgOpenGPS calculations very complex because myself I would not be able to implement any of these. But AOG equally as other screens do calculate the implement path for coverage mapping and they do it quite well, even for complex trailed implements. One could say Fendt “only takes the coverage calculations into the steering control algorithm”. Obviously I have no idea how they really do it.

The idea of creating a trailed tool I had a few minutes ago too. :wink: I will do this asap but now we have to much snow :snowflake: und no possibilities to test it, sry.

Yes, you are right: On nearly flat fields and decent curves it us nearly impossible to see the distance error. But seeding on hills with high side hill draft too (up and down AND left and right) you can see it perfectly after eg wheat is grown up.

You are also right: It is very complex to calculate! I don’t unterstand this too :wink: but Brian is the best ! :wink::wink::wink::+1::+1::+1:

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Just to reinforce the complexity of this subject. In the picture below, the black line is where you want to go, and the red line is where you have to drive to get there. A simple one direction curve is not to bad. Just shift the ABLine to the red line dots and drive. But it matters which way you are going. You can’t just shift all the lines the same amount. Each segment is different. A curve reversal is impossible to drive and stay on the line. When we pull long trailers, we “straighten the curves.” You start eliminating points you cannot drive to and recover from. Therefore, in the right hand drawing you can see that there is no way to drive and recover from the sharp corner mid route. Then you must eliminate that point and drive to the next accessible point. It is the same for the drawing on the left. You must drive toward the modified points only until that point becomes unrecoverable. If you had dual gps with an antenna on the following trailer, you can know how far off the line you are, but you may not be able to drive to the point of correction. I remember seeing video of the fire trucks in New York. They had drivers and steering mechanisms at both ends to turn the corners. This is great work @BrianTee_Admin . And great video.



Thank Brian for the video, very well explain and popularized.

Some questions: you speak only about Standley driving mode, is this new feature (heading error, pivot error, PID etc.) apply only for Standley or it’s also for PP ? Or perhaps I haven’t anderstand and PP mode doesn’t required this ?

Also, how it will work when driving on hill, even for the straight AB line ? On a straight AB line, AOG will align the heading with AB line heading (error converging to 0), pivot point and front axle point on the AB line (error converging to 0 too).
But in case we drive on a tilt following a straight line, we want that the pivot point is on the line (or as said, best is the tool point on the line): but to do that, in order to compensate the tilt, the tractor shouldn’t necessary have the front axle on the line and the heading not necessarry align to the AB line heading. Isn’t it ?

image image

It’s a long time that I haven’t drive our NH T7 with OEM Trimble autosteer, but if I remember well, when driving on a tilt, the autosteer “offset” the tractor of the AB line to keep the implement on the line (we only have rigidly fixed implements).

Thank for all your works,


Hello if I understand well @BrianTee_Admin is not explaining what is already existing but working on new algorithm? True? For the moment based only on Stanley? Pure pursuit forgotten?

Correct, on Stanley only. It may be able to apply to pure pursuit, but i really don’t see the need to have PP at all anymore. Stanley is so very much easier to set up and is self correcting - assuming no outside influence like draft etc. That is where the new stuff comes in. I really do not understand why some experience better results with pure pursuit.

Stanley has certainly been all I have used for a long time, pretty much set and forget i found…

I think PP is very forgiving when something else is not quite right basically.