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

mx270a

To get the cross track error down to this level took some time. Part of it has to do with having a proportional hydraulic valve to get smooth slow steering when needed, and fast response when needed. Part of it has to do with how to get accurate heading data - couple the yaw sensor to the GPS data with a Kalman filter. A steering angle sensor helps, and the steering algorithms were critical to being able to keep the machine smooth. While a 2 inch average cross track error is sweet, my goal is to get that down to the 1/2 inch range.

There are several failsafes built in. The system will not engage or operate at speeds above 6 MPH, the system disengages if the steering wheel is moved, the arduino will close the valve if it doesn't receive any data from the computer for 200ms, and worst case, there is a power switch in the cab to kill the circuit that drives the solenoids on the hydraulic valve.

At the speeds we normally travel at, nothing serious will happen if the system freaks out. At 5 MPH you can stop, shut the system off, back up, and keep going. The critical part is when we're on the road at 20 MPH. While that isn't fast in a car, these machines with rear steering aren't very stable at 20 MPH. When on the road, we flip the lockout switch in the cab so the valve can't possibly open.

-Lance

Chorob

Nice project.  What computers are you using in the cab?

designer2k2

nice application! there are commercial things like this, but making it with a arduino is a lot smoother   :)

mx270a

There are two computers in the cab. One is designed specifically for monitoring the machine and recording data about what it does. The other is a Windows computer for the autosteer system. The motherboard is an Intel D945GCLF2 which has a dual core 1.6 GHz atom processor and 2GB of RAM.

Chorob

Is that a touchscreen monitor hooked to the computer or do you have a keyboard in mouse that you use?  I am looking for a good touchscreen solution for some automotive projects.

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