Alanco's 4-wheel steer

While I was making my Aeon GT3, I was looking at Aeon's sister company's crop sprayer. It has a control which allows it to switch between 2-wheel steer and 4-wheel steer. Keith asked me if I could make the controllers for him, since the person who was previously making them had left the scene.

He gave me one to have a look at. It was a tangle of wires and relays - and the "circuit diagram" wasn't really as such.

So I redesigned it using a microcontroller to do the work. It's functionality is to basically trigger a relay at the right point in time based on two sensors - one in each wheel.

• If you want to go from 2-wheel steer to 4-wheel steer, then you can only do this when both wheels are straight.
• If you want to go from 4-wheel steer to 2-wheel steer, then the rear axle needs to be straight.

Since you don't know what state the wheels are when you start up, there is an initialisation phase where it'll be in 4-wheel steer and then you wiggle the steering wheel until it locks the rear axle straight, and then you wiggle the steering wheel until the front axle is straight. From that point in time, it'll be in 4-wheel steer until you select 2-wheel steer.

The circuit has gone through a number of modifications - mainly to reduce its size, and to make it easier to make.

With the 3D printer, I can now make a case for it which fits directly into the dashboard that Keith is using.

In order to align the two boards, I also made a mounting bracket that holds them in the right place so I can solder the connector: