Is there anyway we could get a list of what each setting in the Steering Config does for someone who is new to the project? For example (Min PWM essentially does this). I’m having trouble getting settings setup even after watching Brian’s Video I still feel like I can’t comprehend what each value does. Its like my motor either does not have enough oomph to get to the set value or it slams so hard it about throws me out of the cab. Just thought having a list would help new comers! Thanks alot !
3 Likes
This is a VERY good question and documenting this would help a huge ammount. I’ve played around with mine a lot to tame it but most has been more luck than judgement!
I’ll list mine, not that they are in any way optimal, but they work reasonably well for me on my 716.
GAIN
Proportional Gain =16
Output gain = 15
Minimum PWM = 25
Sidehill = 0
STEER
Wheel Angle Sensor Zero = obviously machine specific
Counts per degree = 39, but to a degree, as above
Max Steer angle = 38 but as above also
Integral gain = 1
Max Integral = 20
PURE P
I’ve not set these up really because I use Stanley
STANLEY
Agressiveness = 1
Overshoot - 1
Thank You !! Yes I think if I had a list of what each value does I could figure it out a little easier. Plus i’m in a 4 wheel drive Center articulate tractor which makes the concepts seem harder to grasp for me. I have the 24v Phidgets motor to a gear setup on the steering wheel and can’t seem to get the Actual to meet the Setpoint value with out slamming the motor with huge amounts of gain which in turn launches me into the next solar system !
1 Like
Mine is a little too aggressive at time now I’m running my Gimson Robotics motor at a higher voltage but I still want to play with voltages a bit before I alter too much. It’s way too wet here to play with anything on a field!! We had our 936 stuck on sunday, first load with a relatively light tanker!! 
I either have to wait for the ground to freeze solid or wait 6 weeks for it to quit raining…Cant seem to get a good testing day. With the 4wds I have found that setting the tractor up for turning while sitting still can be deceiving because while moving the steering resistance is a lot less. And as far as Pure Pursuit goes … it just turns me in a circle so i’m sticking with Stanlee for now.
hi,
I have the same questions about the steer settings.
After viewing brian’s video about steer settings, i can’t find the right settings. In the video, in steer wizard behind the drive windows is a text that explain all these part of the program but in the newer versions those comments are gone. And i can’t find the older versions of aog.
So is it possible to find all this explanations elsewhere?
The fine tune of the steering is very important to use all the possibility of AOG
Thanks!
1 Like
Hi everyone,
i just started and build up a simple guidiance system with AgOpenGPS.
In the vehicle files I found values for PID.
My Question:
Is it possible to use those values for calibrating the steering behavior?
In earlier Versions i saw (in pictures) a PID Formular in AgOpenGPS.
Thank you and sorry for my bad grammatics.
Yes the steer settings are used for exactly that ! We are trying to get a compiled list of what each setting does and how it affects steering behavior.
Sounds good. I have a few problems to find the right settings.
Thank you.
By the way, i think its a great software 
For now…
The difference between the steering angle requested by AgOpenGPS minus the actual steer angle of the vehicle is the “Error”. This error is used to determine how much and how quickly the steer motor or valve should be controlled.
The error times the different gains set will generate a number from 0 to 255 and be converted to a variable pulse width signal to control the steering. 0 is off and 255 is fully on. Minimum PWM value is used to apply a minimum amount of power to overcome friction of the valve/motor so if a steering adjustment is required, it will occur immediately.
The proportional gain and output gain are multiplied by the error then added to the minimum PWM value to generate the final output value. The higher this value the faster the motor will correct the steering. However if it is too high, the steering will overshoot the line and then oversteer the other way again. Too low of a value and it will either take too long or never get to the guidance line.
PID is Proportional, Integral Derivative type control. P is the error that is right now, I is the error that was, and D is the error of the future. The Integral is an accumulation of the error over time. When it gets big enough a correction will try to eliminate it. The Derivative is the rate of change of the error. A high derivative value suggests we are really zooming towards the line. All we are using is the proportional value since pure pursuit solves many of the oversteer issues of a traditional pid loop control system.
Draft compensation uses the roll of the vehicle to help turn up hills. As you drive on a steeper and steeper sidehill, it takes more steering angle to hold the line. Turning forced higher then the line helps to remove some of the sideways draft of a piece of equipment.
Look Ahead is the value that sets the response of how quickly and sharply the vehicle will steer back towards the line. The faster you go the farther out the look ahead point will be. A very small (1 second) look ahead will make the steering turn very quickyl Like too high of a proportional gain, a very short look ahead value will make the vehicle turn abruptly to the line and may overshoot it and oscillate a few times across the line. A very high value will make very small steering adjustments and take a long time to get back to the guidance line. The correct value is of course somehwere in between.
The steer angle sensor zero is used to make sure the steering value when driving straight forward shows a steering angle of zero. This is very important to be correct. You can watch the heading slowly change to determine if you are slowly turning one way or the other. You can also use “Drive” set to zero and then adjust the steering zero until the heading remains constant.
Counts per degree takes the raw value of the Arduino measuring the steer angle sensor and turns that number into degrees. Example, if the wheels are at 10 degrees and the raw value is 90, then the counts per degree is 9.
The chart at the bottom shows the actual (the value of the steer sensor of the vehicle) is in Red and the desired generated steer angle (the setpoint by AOG) is green. It is quite helpful, if the steering should wildly go back and forth across the setpoint - gain is too high, or if it should take forever to get to the line - gains are set too low. It really demonstrates what is going on since constantly changing numbers are impossible to show anything useful.
7 Likes
Thank you for your very extensively answer, this should help to find the correct settings. Perfect. I will report after i found the right settings. 
1 Like
Its working now, the video was helping
1 Like
This is great ! …One question though …How crucial are the Integral settings they aren’t mentioned much in the video.
They aren’t used. So not crucial at all…
Evening gents, I didn’t want to start another steering thread so I guessed here is a good spot.
Did my first run with the system today, t7.250 New Holland with AoG controlling the valves and using the tractors own WAS. Antenna on original plate around 30cm in front of rear axle.
All in all it works very well but had a few snags. After a lot of changing settings it was running nice, little oscillation left and right over the line, but at 2 points in the field on each run the tractor would turn very sharp to the left drifting out around 1.5m then return to the line, when this happens the AoG screen spins the opposite direction then settles down. I did Ab line and Ab curve but it happened on both, even started a new field. I swapped between Stanley and Pure Pursuit but was the same. Field was flat and level. Amy ideas where I might be gone wrong?
You are using CMPS14?
Yes that’s screwed to the roof of the cabin.
That happened to me in only one field with the CMPS14, you can change field and try again.
Unfortunately the solution I took was to change to the BNO085, and I didn’t try to move the CMPS14.
1 Like
There is 2 speakers to the left and right of it around 30cm away, maybe getting interference from those? I will try move it somewhere else in the cabin today.