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hydraulic_steering:start

Hydraulic Steering

Steering Wheel Encoder

Also known as a rotary encoder or incremental encoder. It produces digital signals while turning the steering wheel.

The encoder is used with hydraulic valves only, it is not necessary to use with a steering motor.

It can be used with AGOpenGPS to disengage the autosteer; if you turn the steering wheel manually while using autosteer, the autosteer mode is switched off.

Most professional Systems are using it (e.g.John Deere)

Hollow shaft encoders like this ones from fiama could't be used:

http://www.fiama.it/en/trasduttori-rotativi-potenziometrici-e-incrementali/125/1.html

Typ e.g. EN25-100-TTL-LD2 (25mm diameter, 100impulses/turn, 5V supply, 5V Output)

Connected to a interrupt pin:

Sometimes they are using 12V supply, you have to prove if the outputs are delivering 5V impulses, otherwise a voltage divider must prefixed!

Prepared Sketch: Autosteer_AIO: http://github.com/Coffeetrac


PWM - Valve 2-Coil (CQuick)

You will need to know the type of hydraulic circuit your tractor uses. It is usually either Open Center or Closed Center Load Sensing (CCLS). you can tell by checking the Orbitrol unit at the front of the steering column. If it has 4 pipes, it is OC; else if 5 pipes, it is CCLS. The fifth pipe carries a signal to the pump whenever there is demand for flow. Some tractors pressurize the pipe, others depressurize it when demanding flow. You will need to know which style your machine uses. A workshop manual for your tractor is useful for these purposes.

If your tractor is OC, you will need a valve like this:

https://www.savery.co.uk/products/view/sp10-47c-spool-4-way-3-position-closed-center

If your tractor is CCLS, you will need a valve like this:

https://www.savery.co.uk/products/view/sp10-57c-spool-5-way-3-position

you will also need a driver module IBT_2 (if the Link fails search for “BTS7960 Module”)

https://www.amazon.com/s/ref=sr_qz_back?sf=fr&rh=i%3Aaps%2Ck%3Abts7960&keywords=bts7960&unfiltered=1&ie=UTF8&qid=1523798188

You will then need to tee into the Pressure (P), Tank return (T), A, B (to the steering ram) and LS ports of the orbitrol, and connect them to ports 5, 3, 4, 2 and 1 of the valve respectively. Swap 5 and 3 if the LS line is supposed to depressurise when flow is demanded.

Alternatively, you can use the Power Beyond functionality of your tractor (if fitted), or a spool valve set to constant pumping.

Schematics 2-Coil PWM Valve:

Prepared Sketch: Autosteer_AIO: https://github.com/Coffeetrac

When setting up the PIDs, be aware that the steering can be very sharp and fast with hydraulic. A good starting point is: P 200, I 20, D 30, O 1.


Danfoss Valve (weder)

danfoss valve is widely used and installed by john deere, fendt, trimble. novariant steering job computer (mueller) can handle it too.

Working types are PVEH / PVEA / PVEM, but since there are Canbus and Blackwhite ones you have to check carefully!

Danfoss valve always has following control head:

Block on picture could be manufacturer related e.g. john deere (Closed-Center, LS)

or block construction, there are Open-Center and Closed-Center available

or directly as substitute orbitol

this head is controlled analogously via simple potentiometer:

or via the arduino using PWM pin:

(in addition, supply voltage is switched off via another pin)

Complete Schematics Danfoss Valve using the IBT_2 module

Prepared Sketch: Autosteer_AIO: https://github.com/Coffeetrac


hydraulic_steering/start.txt · Last modified: 2018/10/08 08:35 by dokuwikiadmin