DIY AutoSteer with AgOpenGPS - Page 2 - The Combine Forum
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post #11 of 2024 (permalink) Old 04-16-2017, 01:17 AM
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Originally Posted by MountainviewTruck View Post
You guys are brilliant. I am a total greenhorn when it comes to GPS and auto-steer. I know nothing about nothing, and would love to know more than that! I left the ag dealer back in 2000, when precision farming was in it's infancy. I don't want to hijack this thread, but can you point me in a direction of where I can start to learn?
Well, I know for a fact that my knowledge is just enough to be dangerous haha! However, I can build on the incredible work that Brian and a few others have been generous to open up to us. I am also excited to see the whole setup evolve as others join in and help refine everything!

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Last edited by Wedge; 04-16-2017 at 01:18 AM. Reason: wording
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post #12 of 2024 (permalink) Old 04-16-2017, 02:51 PM
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Originally Posted by Wedge View Post
Brian:
-Should we as a group decide on a specific output format(or two) from the control system? Maybe pwm? Range? Are we checking a steering sensor? Specifics help in design!
I'm using the PWM to drive a DC motor, the range would be an option for those who wish to try with servos?

For the steering sensor I'm planing to use an encoder attached to the autosteer motor + a reed relay for "zero" sensing.
Whe can always have a "low level layer", so we normalize the steering sensor input (be it encoder, potentiometer...) to the PID function.

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post #13 of 2024 (permalink) Old 04-16-2017, 09:09 PM Thread Starter
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Originally Posted by Wedge View Post
Brian:

Good idea with the new thread. Should keep the AOG thread cleaner since we are working on a slightly different stage now!

A couple questions for anyone:

-Will it hurt anything if, rather than computing the PID on a timing, we just ran it every time we got new information? Potentially a little more wild depending on data? This leads into filtering the output......

-What is everyone using to dial in their coefficients in the controller? I have put together a PID controller that I have just been running on the Ardunio w/AOG and watching the writeback values to AOG while steering. Gets a rough approximation, until I can put together a physical control system.

-Should we as a group decide on a specific output format(or two) from the control system? Maybe pwm? Range? Are we checking a steering sensor? Specifics help in design!

One more for Brian:

Is it necessary to have both a section control and an autosteer communication option in AOG if the section control is sent through the autosteer as well? Maybe wrap them into one? Or are we looking ahead to $$$$ unlocks here? Hahaha!
That's a lot of questions! I shall make a video and explain what i have done in regards to a lot of this. Fortunately this isn't all that new, i've been able to use experience gained from 2 wheel balancing robots to apply to this project.

I think since there are already 2 serial options, Relay and autosteer, send the relay info to both. That way it doesn't matter what you use.

The first post lists the output format from AgOpenGPS. It will be updated as things and ideas change - as they always do.

PID i feel should be calculated based on the timing of the rec'd information, it is accurate enough, consistent. And simple, there is no math required for timing at all, for example integration is just addition, derivative is just the difference between this and last or lastlast error, and Proportional, just is. Each then is just multiplied by its own respective gain.

Coefficients will be different for every motor/steering/vehicle combination. But with some experience, should have some good starting points. It really depends on the normal oscillation of the system and the length of time that is. It can be pretty tricky to adjust PID values, but that is what makes it fun.

I've built in a system in AgOpen to allow adjustment of PIDO values, i hope its acceptable. You can increase and decrease 7 values by sending a single 8 bit byte.
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Last edited by BrianTee; 04-16-2017 at 09:25 PM.
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post #14 of 2024 (permalink) Old 04-16-2017, 09:11 PM
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Originally Posted by MountainviewTruck View Post
You guys are brilliant. I am a total greenhorn when it comes to GPS and auto-steer. I know nothing about nothing, and would love to know more than that! I left the ag dealer back in 2000, when precision farming was in it's infancy. I don't want to hijack this thread, but can you point me in a direction of where I can start to learn?
What aspects are you wanting to learn? There is a vibrant beginner's community around the Arduino microcontroller. http://arduino.cc

That might be a good place to start for learning about robotics and sensors and control practices.
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post #15 of 2024 (permalink) Old 04-16-2017, 10:32 PM Thread Starter
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A not so short video on Autosteer. I noticed when i spoke of distance error = 32020 and 32000, I should be saying OR not AND. If the distance is 32020, the autosteer is off, if its 32000 that means there is no distance to calculate, as in there is no contour line within detection.

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Last edited by BrianTee; 04-17-2017 at 12:46 AM.
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post #16 of 2024 (permalink) Old 04-17-2017, 01:02 AM
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Nice video! I like the ability to adjust PID values in the fly. Much easier for tuning then using a serial console manually or reprogramming constantly. Would there be any usefulness with saving the PID values with the rest of the tractor config data? Maybe being able to send those values to the Arduino at the initial connection? I'm thinking ahead to when I'll have AOG in our fleet of tractors, Arduinos and tablets might get swapped around but I'd like the tractor config to stay with the tractor settings. I'm also thinking of using something like Dropbox to sync between tractors.
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post #17 of 2024 (permalink) Old 04-17-2017, 12:54 PM Thread Starter
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A video showing an actual steering motor hooked up and a quick look at the circuits. BTW, the steering position sensor will be used to limit the angular velocity of the turns. The faster you go the lower the amount of steering should be allowed. So if the PID loop wants to turn it more then that limit, you just zero it. Code not written yet, but that's pretty easy. Since there is a foot of snow on the ground, got some time to fiddle.

Video showing the setup.

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post #18 of 2024 (permalink) Old 04-17-2017, 05:46 PM
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Awesome videos Brian!
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post #19 of 2024 (permalink) Old 04-24-2017, 11:15 AM Thread Starter
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Does anyone know what is required for proportional valves for auto steer? Can you buy a steering block without going thru Outback or Raven etc?

Any hydraulic gurus out there?
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post #20 of 2024 (permalink) Old 04-24-2017, 11:22 AM
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As far as control goes, Matt Reimer used a standard PWM 12V motor controller to drive the two solenoids for his autonomous tractor. PWM on one solenoid to steer in one direction, and the other to steer in the other direction I'm presuming.

I can't remember what valve block Matt was using.

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