Apm Rover in tractor setup.

I want to use pixhawk with the apm rover firmware to operate an agricultural tractor. I need to set up my tractor as an rc vehicle.  My plan is as follows: any feedback I can get is appreciated.  I plan to order the parts in the next couple days but if there is something I've overlooked or my plan has no chance of success let me know.

Throttle control: Linear servo (https://www.servocity.com/html/25_lbs__thrust_linear_actuator.html#.VVOUCJNyP5U) I don't see too many problems here.

GPS: I plan to use the gps already installed in the tractor.  I am planning on buying a pololu 23201a to convert the serial nmea to something I can input to the pixhawk.

Steering: This is what I'm most worried about.  The tractor has an electric over hydraulic steering valve, so basically provide 12v to right side tractor turns right, provide 12v to left side tractor turns left. I am planning to put in a dual 12v relay controlled by pwm signals for the steering https://www.servocity.com/html/electronic_pwm_controlled_dual.html#.VVTFmZNyP5U  Anybody have a gut feel on whether this will work or not?  The problem is the steering output from pixhawk needs to reach a certain threshold before steering valve will operate this is quite a bit differnt than how it is set up on my rc car where each pwm value corresponds to a specific steering angle.

Clutch: Much testing has to be done with a person in the cab to operate the clutch and some sort of ignition failsafe installed before I get the tractor to be totally autonomous but I would like to start thinking about the clutch, and start testing some setups with a person in the cab.  I could get a linear actuator that releases the clutch when throttle pwm reaches some predefined threshold? But I would really like a system that if the power is cut or signal is lost clutch is automatically depressed which will stop the vehicle. I could set the clutch up to be always depressed and use a linear actuator to engage it. Connect the actuator to the clutch with an electric solenoid so if power is lost actuator releases and clutch disengages. Anyone else have some good ideas?

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  • To anyone still following this thread.  Here's Matt's year two modifications, main thing is panel PC implementation.  In this scenario where is the radio from the master?   I believe he was still using the 3DR radios so were they tied into the panel PC or is the RC remote (can't remember the model/brand) still in play?  I need to dig a little further into mavproxy and if/how that's running on the panel PC


  • Hi again Matthew, ignore the above post, I was able to find you Github info.  Back in the threads you provided a link to the Outback valve you used but that link no longer works due to Outback changing/updating their website.  Is this valve along the lines of what you put on your JD?  I know these are for Open Center systems and your JD was likely load sensing, closed center but I'm just trying to get an idea before I call Outback and look like a complete idiot.  I'm looking at doing an Open Center implementation TIA  (Thanks in Advance) 



    760-0007 Assy, Hyd. Valve Block - OC/HF Low Range
  • Hello Matthew, love what you have done here.  I can't seem to find any of the software up on Github that you mention.  Did you pull it off of there?  Cheers and congrats on some great work.

  • Hello, How did you create the custom mavlink message to send the tractor health data to the gsc? I know you used serial to write to Pixhawk from the Arduino and then using serial 4(uartE) to get the data but how does Pixhawk use mavlink to send it to the Microsoft surface and how do you modify the mavlink xml file for Pixhawk and Microsoft surface? I understand how the Arduino reads and writes to Pixhawk, I am just confused on the process of taking that information from Pixhawk to the gsc, hopeful you can shed some light in this area for me.

    Matthew Reimer said:

    Here's a very brief video showing the working prototype I have made for streaming engine data.  The code on the arduino is up on github. The code on the pixhawk and the modified mavlink libraries will be up eventually as well.

    Apm Rover in tractor setup.
    I want to use pixhawk with the apm rover firmware to operate an agricultural tractor. I need to set up my tractor as an rc vehicle.  My plan is as fo…

  • Grant, Any update on the geo fence for rover capabilities? I think the obstacle detection/avoidance feature would be very useful as well. 



    Grant Morphett said:

    A sonar on the front (or 2) will enable the vehicle to detect the object and it will make a decision regarding going left or right around it.  However, it wasn't designed for large vehicles with slow turn rates and the effect range of the sonar (7m to 10m) probably isn't far enough for your purposes.  We would need to test.

    The other alternative is LiDAR which goes much farther but again you would need to test.

    At the moment there is no way to specify an object in the driving area and tell the Rover to avoid it.  Rover doesn't currently support geo-fence's but its on my list.

    Thanks, Grant.

  • I'm amazed at the speed with which you were able to do this...especially considering it was in the middle of the growing season!

    • No one is more surprised than me how it all came together.  A lot of credit has to be given to the other guys I work with on the farm.  They had some good ideas as we were working and they really picked up the slack because as you can imagine I didn't work as much in the field last year as I normally would.

    • Matthew!

      What a nice job! awesome.

      I have plans to do the same and have ordered parts that is going to be used.

      Have you planned to use DIY RTK equipment?

      I plan to use Lattepanda with Arduino on the board and install RTKLIB in Lattepanda.

      I am not sure if i can send NMEA from Lattepanda to Pixhawk into GPS no.2 input.

      Have you tried this?

  • The final design is really starting to take form check out the latest video I posted with an overview of how things look in the cab.  If anyone with a JD7930 tractor is interested in doing the install themselves let me know.  I'm prepared to offer a kit for this model.

    • Hey Matt, we have a 7920 and are interested in a kit for sure.  Let me know what kind of price range it will be in when you figure that out and we'll go from there.  Very interested in your work!  Keep it up!

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