Swather steering without WAS

Would it be possible, or has anyone setup a swather to steer without using WAS. Maybe use feedback from dual antennas?

Check out this topic. I think you guys are talking about almost the same thing.

Yes and no. I would be thinking of steering with steering wheel motor. I wish I knew how to code because i think it would be a fun challenge. I think quite a few people would end up using it if someone could just write the code.

Swather steering is quite a challenge. Obviously it is done by commercial units. The hard part for the current algorithms in AOG is that swather steering dynamics change based on speed. Turning the wheel the same amount give very different turns at different speeds. Perhaps instead of a WAS, going by yaw rate would be best. Zero yaw is straight of course. A dual receiver setup could probably get you a fairly good yaw rate, especially at 10 hz update.

I suspect it would be very easy to get into oscillations the way a swather steers(even a novice driver can have problems driving manually). PID tuning would be quite a challenge.

Actually this is the very thing they are talking about on the other thread. Think it still applies to using a steering motor wheel. However tuning would be way harder with how the swather steering is inputted vs the differential cart in the other thread.

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While this isn’t a swather, and I’m not 100% sure what the company is that makes the system installed, this commercial system uses a gyro to determine “wheel angle” on an articulating tractor:

Perhaps something along those lines would be usable on a swather.

I realize the amount of data in the video is moot, but just knowing that is how other persons in the industry do it shows that we are heading in the right direction with this idea.



Pro 700 - one of the many reasons i continued to write AgOpenGPS!


It’s called an AutoSense and it’s made by Trimble. Many CaseIH machines with factory auto steer use it. Someone took one apart: Viewing a thread - Inside a Trimble AutoSense (Pics). The main sensor seems to be a single-axis Gyro from Silicon Sensing Systems. I’m not sure if there’s a magnetometer in there. Also not sure how it calculates the steering angle but we can make some guesses. The manual talks about how you must be moving for it to work.

Seems like another simple way would be to have a speed sensor on each drive wheel and calculate a steering angle based on the differential speed.

Personally I don’t mind the Pro 700. Guess I’m used to it since we have it on four different machines.

I have one of those gyros CRS43, which is the newer version sitting on my workbench. Also a BNO080 i should hook up some time.