Direction detection problems (With Dual as IMU)

Thought I would post on here rather than the chat group as easier to keep track!

After finally sorting out my V5 problems which I have been fighting for the best part of a year, I finally have a stable GPS position on V5 and things working much much better, which is great as its had me scratching my head for a long while!

One problem though, that is becoming increasingly annoying now that im into the silage season is the direction detection playing up…and I am wondering if the fact im using dual (or specifically, the fact the position antenna is offset to one side…) is exagerating the problem hugely, as many I speak to dont seem to have any issues…

So my setup is Dual GPS, using Tony’s basic code over UDP, which is super stable and fast I am finding… I use “Dual as IMU” as this prevents the typical Dual heading vs direction problem, which helps massively on a sidehill, or with any side draft in regard to keeping on the line… Because of this, direction detection is then a thing (which when using pure dual, never has been, and just works perfectly as you only use the true dual heading, which is obviosuly always instantly correct)…

What I am finding it probably 80% of the time, when turning on the headland, it will get mixed up, and be going the wrong direction when entering work again… This in itself is a bit annoying as you have to keep and eye and hit the tractor icon every time to correct it…but the REAL problem, is the fact that this then obviously hugely winds up the IMU fusion…so when you hit the tractor, it will take a fair distance for it to get “back in sync” again and drive correctly… This is obviosuly impossible when turning on the headland as you have no space to drive fowards enough for this to correct, which results in having to steering manualy for the first 20feet of every pass until its settled down again to hit autosteer…Which happens more often than it dosnt, so is getting rather annoying to say the least!

If you take long turns it generally works ok, its nearly always when you have to back up you get the problems, it seem to be if you back up at full lock, and then go fowards at full lock, this will almost always confuse it… And as I said before, I wonder if this is hugely influenced by the offset position antenna in a dual setup, meaning you are “driving around” the position antenna when at full lock, which makes it much harder for AOG to detect direction?

@BrianTee_Admin @BrianTee any thoughts on this? A workaround would be that hitting the tractor resets the imu fusion so that at least it would work once you hit that icon each time… But going fowards, how much work would it be to code in direction detection which is only calculated using the incoming heading from the DUAL, not the fix-fix… As this heading is always 100% correct, no delay, its just right, even if stationary… This would essentially fix all the issues I think?

At which value have you set your start speed? Try with something above 2-3 km/h

I did try mesing with this (I need 1kph as we plant veg at very slow speed) but changing it to 3kph for other jobs makes zero difference anyway…

In my experience, the direction detection works better when the antenna is closer to the rear axle. The farther it is away from the rear axle, the more often it is wrong.

I read so many messages about this antenna position that I was in a dilemma. The number of people who put the antenna in the front and say it’s perfect is the same as the number of people who are satisfied with the axle. But commercial systems always mount it above the cabinet.

I thought that with dual antennas, direction is always perfect since it’s always readily apparent which way the tractor is facing regardless of whether the tractor is moving forward or reversing. Direction detection is used with single antenna, isn’t it? Why is AOG getting confused with a dual antenna at any speed?

Dual antenna is good in normal driving. The problem with normal dual mode is on hills when the tractor is sliding sideways the heading the tractor is moving is wrong.

In the early days of this problem Brian just made a quick mod to use single fix/fix mode to calculate the true driving heading then use dual data as the IMU. That fixed the heading error when sliding but I don’t think anyone has had time to go back and write some code to use the best of both options.

Dual for direction, antenna correction, pivot point calculation etc and then fix/fix heading to determine the sliding angle and add that to the mix and drive to the line.

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I think you are nearly on the money with that…

When using V4 (and i imagine v5 would be the same) in true dual mode (the only option) the tractor is always pointing fowards in AOG…there was no “reverse” mode, as it didnt do reverse guidance… BUT when using dual it just happened to work perfectly in reverse also (by luck more than anything I think?), but meant that you could just shunt foward / back at any angle, in any position, and you wouldnt even have to dissengage autosteer as it just “worked”…


As above, the dissadvantage of true dual is that the “heading” from dual is actually the direction the tractor is pointing, not travelling…therefore if you get any drift / side crabbing, which is always going to happen on a hill / with side mounted implements, you then have big trouble staying on the line…

The fix was “Dual as IMU” which I can confirm works super well, with a fusion between the dual heading and a fix2fix heading, you get the best of both worlds, and I can confirm this season its almost faultless, even with a 10ft side mounted single mower, I was completing entire fields, even in hills without touching the steering wheel… So that is super!

However now get the problem in original post with direction detection…

There must be a way :slight_smile:


Just seen this after posting on telegram. 5.6 is epically worse on reverse detection for me. To the point of being unusable. Even long fix settings make no difference. U turns are very poor too. 5.2 is miles better. Ended up back on that today. Jut sure why this is the case?

I strongly suspect agIO personally. It seems less stable. NTRIP issues , ie difficulty receiving a mount point list hang agIO very easily.

I’ve had ro force close agIO several times.

Increasing tractor turning radius improved u turns for me. They work very good now.