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Topic: Steering a combine via GPS (Read 12 times) previous topic - next topic

Capio West

Definitely must reiterate others' comments... it's great to see someone driven to apply these 'hobby-friendly' microcontrollers to a realworld application, especially a project so connected to your daily work/life. Kudos.

And of course, the scope of the effort speaks volumes too.

Saw your photos/webpage:
wanted to confirm that the driver circuit would work, that the solenoids work, and get a feel for how big the deadband is. Everything was successful. How many farmers do you know who have an oscilloscope in the shop? (pic)
Now I know what the expression "the Farmer and the Dell" means!


Hi Lance,
your project is pure inspiration.  On your site you make the statement:
  • "What is Lefebure.com GPS? This is a project to build an auto-steer system for agricultural use. More specifically, the system uses GPS data to create a coverage map, and also to steer the machine. The original goal was to build a system that is more intuitive and less expensive than anything else on the market."

The line I've underlined shows that you've achieved your goal.  And to think this is your 1st Arduino project!. Amazing.

It really show cases what Arduino is capable of.


You may want to look at the codes in the a programin[/url]g for some help in integrating the gps data and stearing into the arduino. the project is aimed at rc airplanes but it might give you some directions to consider. There are examples of gps parsing there too. I know there is a lot of ground based robots running the code.

I would love to see more details of your system, ie valve control interface etc.. :)



now maybe it will let men link.

Ardupilot [url]http://ardupilot.googlecode.com/files/ArduPilot_24.zip/url]


I've read a bit about the ArduPilot project, and it appears to be growing at a healthy pace. I'll look into it more deeply in February/March when I start prepping for spring planting. Working on some other projects currently.

I think it would be easier to couple GPS to IMU data on an airplane due to the high speed. The slower you go, the longer the time delay between when your heading changes and when you can pick that up in the GPS data. Even the big name companies are only able to make it work down to about 0.5 MPH. In addition, the location of the GPS antenna relative to the solid axle has an effect on how the GPS data can be used to correct the IMU data.

The valve controller is a pair of N-channel logic level mosfets that drive the two solenoids on my hydraulic valve. I think I even got the basic schematic off this forum, and adapted it for my load requirements.

Basically there is a Windows computer that gets NMEA data from a GPS receiver, determines how far offline it is from the target path, adds any tilt correction to that, and then determines what angle the steer axle should be at to get back to that desired line. Then a PI loop takes over and moves the steering valve left or right to get the steer axle angle to the desired position. The windows computer also keeps track of where the machine has been (coverage map) and shows that to the user as a 3d map in DirectX. The coverage map can also be used to turn things on and off to eliminate overlap of chemicals, seed, fertilizer, etc.


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