The tractor in this story is a Kubota M5091. At the beginning it all started with completing the parts - standard PCB from the author AGopen from JLCPCB, ordering electronics from digikey, the rest here locally in Poland. Of course the RTK kit from Ardusimple (1 base and 1 rover).
And Rtk mount base:
DC Motor:
At the local auction site (Allegro) I was able to buy a DC motor with a planetary gear (unfortunately the downside was that the motor was 7-8rpm and the output was max 150rpm, so the motor often became warm due to a quick change of direction). Mount I designed in Fusion360 and print by my 3d printer:
Minuses? You need to “unscrew” the engine to be able to turn the steering wheel.
Second version - small stepper motors
The second version was based on two small stepper motors connected by a strap GT2 to the steering wheel. However, these engines would have too little power to turn the steering wheel. Previously I test many of clutch from printers but no one has enough torque to transmit it from motor to steering wheel (the clutch plates were skipping). But the big plus was that with the engines off (when agopen disengages the steering), you can turn the steering wheel with the motors without any problems (no need to remove the belt, etc.). :
Third version:
The third version already uses a more powerful engine - it turns the steering wheel without any problems - when AutoSteer is off, you can turn it alone with the engine connected without removing the GT2 belt:
Mounting the GPS antenna
The GPS antenna is mounted in the center of the tractor, flush with the cab - currently it is also testing the installation of the antenna above the steering axle at the front of the tractor - the effects are a bit better but still not perfect;)
Sensors?
I use BNO080 for heading and roll.
Current Effects?
In the meantime, the tablet is better mounted so that it is stable;):
Current problems?
The tractor runs fine, however:
• Has trouble detecting field inclination - often does not follow the line
• The system does not want to follow the line - the bars run away, indicate for example -5 and the tractor does not turn right, but goes straight ahead. Only a few line shifts help him
• May be adding hydraulics in the future;)
Additionally:
Bravo 300S interface to AGOPENGPS
The interface is my own project - it is the ESP32 which mediates between the Bravo computer and the switches. The system can operate autonomously or in the mode with AGOPEN. I removed the original board with switches, did a reverse engineering and designed my own PCB - matching plug and play in place of the original PCB:
Oryg PCB:
My PCB:
Additionally - RTK relay.
By default, around the farm (max 3-4km) I use RTK with fields, which is transmitted via SX868 RF modules. However, the base station sends the correction over the RF but simultaneously to its own NTRIP server. When driving outside the RF coverage area of my home, I take a retrasmitter with me that downloads RTK from my server and transmits RTCM to tractors in a given field - it simply imitates an RTK station.
This makes work easier because we turn on such a ready set and in 2 minutes RTK is already working - you do not need to run a hotspot for a computer or switch the RTCM source in ublox ucenter as a COM port;)
This is the end of my story - if you have questions, here I am. If someone would also like to help, I would like to listen to people who know more about this system because I have only been interested in it for a year 
