# Uturn or 8Turn V5.6.2

hello
i see a strange U turn or probably more an 8Turn

do you already see that ?

V5.6.2 a basic AB line not realiy perpendicular …

depend of the speed but he can catch Uturn or 8Turn

i attach the field ( remove .txt) to try
ligne.zip.txt (52,5 Ko)

1 Like

The 8 turn appears when you have turn radius set at exactly same as uturn.
Eg uturn at 6m(perhaps it’s 12m)set radius at 599 cm
The 8 turn also happens in AOG ver 4

Thanks for explanation

I m surprised when i see that because never see before since 2 years

It did not happen every time, but have seen it on two different ver 4 setups. I also think it was only to one side.
Have not seen in v5.5 but maybe because I already set turn radius different

Turning radius set the same as distance from boundary? which setting in uturn? I do not fully understand?

Distance from boarder: if implement is in hitch, then half implement width will do.
If towed implement, you can set much closer to the boarder without hitting boarder.

I recheck this and not so easy to resee again

If i increase turning radius it is ok but if i reduce its appears around 2.5meter

It is not a major bug that i never see before so that why i m surprised

If you want to resimulate with the field that i send find the tractor config

test tractor .XML.txt (19,8 Ko)
remove “.txt”

but it looks working correctly at 0,7,8… but not for 1 2 3 4 5 6 …

0

1

6

7

The 2.5 m is the lower limit turning right, when turning left you can go lower. Has always been there. Not a u-turn thing.
When driving faster, limit is higher.
Watch steer chart turning right and left, you see jumps out of circle when turning right. In my opinion it is the math behind. Like negative times negative gives positive.

I discover this with the simulator it means the perfect steering

If you go fast it sometimes folow the U but in low speed the 8
by the way the Math generate this and the screen show this 8 and it can be a confusion

it is appears only one side …

it is an 0.0001% problem

It’s a calculating error in the dubins path generation.

It only appears when the youturn offset / turn radius is a whole number.

Easy fix is too increase the minimal turn radius with 1 cm.

1 Like

Thank you to danielP for the simple solution.
bricbric we were discussing this long ago, maybe some of the explanations can help you to not choose “bad settings”
I know some of the issues has been solved, there even was a Narrow tractor version of AOG once. And I cant make sim tractor go out of circle as it did in 2019!

Different problem. This was driving through the turn. I’ve seen the figure 8 from time to time. This is a dubins error. Probably easy to check for now that we know the problem. The sharp turn problem is fixed by more points closer together in the uturn. I believe this has been fixed already.

1 Like

You are absolutely right.
And as you seem to know how to do the programming, maybe my observation here helps to sort the bug:
Sorry bricbric but my AOG on stationary computer stalled because I have no steer-board connected and only running ver. 5.4! (had to delete user.config to continue, after loading test tractor.xml)

In figure 6 the u-turn go 90 degree right and “must” stay between yellow and green lines therefore does a circle to hit the correct track on line.

But in 7 the U-turn follow the boarder and can still turn down correct track on line.
I remember at some time “months ago” the program was improved, so following the boarder was possible, maybe this improvement is not implemented at all types of skips?
(Maybe if distance between yellow and green was bigger, or a different angle between boarder and AB line would change the behavior)
I know that my 8 shape in ver4 happened at 1 skip, coming to a boarder at an angle of around 45 degree.