Thought I would write up a project on here to share my little project that I have been working on.
Have used Farmer GPS for many years on a tablet in my 6630 tractor, connected with serial to a SF3000 John Deere GPS receiver. No activations, just basic SF1 signal.
After changing our combine last season, and it already having autotrac on it, it changed my life forever, and not having it in the tractor was simply not an option any more!
But have always known that if I was going to get it on the tractor, I wanted RTK accuracy so i could go back to the same point year after year, or else I couldn’t really justify int he investment. But after looking into the cost of doing that, using OEM parts, and the biggest killer, activations…welll…thats where AOG comes in!
So started out just using AOG on the tablet in place of FarmerGPS, still driving the tractor myself, to get used to the software, then started my project of autosteer!
Due to awful weather, and tractor in constant use in the yard, The first thing I actually did was build the RTK base station, which I wouldn’t be using for some time, but just wanted it done / running and sorted, I already made a thread for that, which can be found here:
And a picture of it installed:
Ordered up the components, and PCB and set about building the PCB:
Connecting via UDP as want to use UDP for all elements of this system, I think its a nicer way to connect everything, and already have ethernet switch / network in the tractor, as well as a long range wifi link which keeps my online on 98% of my farm, and 4g failover from mobile teather if it fails.
Put it in an enclosure, used some Weipeu connectors, as recommended by @BrianTee_Admin (Thanks Brian there great!), to make it easy to remove if needed. Also some relays etc for various things, fuses etc also buried in there.
Also made a control panel for in the cab, main power (turns on PCB, and gives power to everything in the system via main relays. Also has two safety lock switches, one kills power to cytron , the other kills power to a hydraulic shutoff valve before my steering T’s to isolate system totally for on the road. As well as a work switch to map when implement isnt connected itself, and also the main autosteer button (momentary)
Made a bracket and mounted it in the cab:
Next up was wheel angle sensor, decided to use the landrover suspension sensor, mainly because it was easy to get hold of here (UK) and cheap / easy to replace in event of a failure, and thought if it was designed to be in muddy wheelarch, it should be fairly well protected…
Built a bracket first to mount it:
Painted it up and fitted to the tractor, also upgraded the plastic linkages to rose joints, mainly to give me fine adjustment, so i could set straight ahead at precisely 2.5v, and also as stronger / should last longer with zero slop.
Just picks up a factory bolt hole on the axle, and then clamps around the entire axle, super solid / didn’t want to weld / modify the axle at all.
Then for the hydraulic setup, ordered up the valves and fittings, Corona virus in full swing now, so having to order everything online, including the hoses, which found a cracking website for custom length hoses, with endless choice of fittings, and actually cheaper than my local hydro outlet!
Made up a bracket to mount everything on:
And got it mounted under the cab:
The tractor is a load compensated system, but fixed displacement (gear) pump, so basically works like a full CCLS, with LS line that brings tractor up from standby pressure to main pressure when pressure is applied to the LS line.
I T’ed the stock orbital output lines, and pulled my Pressure (P) tank / return (T) and Load Sense (LS) lines from the powerbeyond system on the back of the tractor, firstly because I didnt want to interfere with the stock orbital system for safety, and also because theres no bleed on the stock orbital LS line, so would require a orifice or else system pressure would stay up.
I have a power beyond block already on the tractor as it has a front loader, for which the valve block is mounted in the same place under the cab, So to save long pipe runs, I was able to T the P / T lines right there next to the block, and also the LS line, with a shuttle valve fitted so either valve can call for oil without back feeding each other.
Got it all wired up at this point and ready for first test, Eventual plan is to run dual F9P’s with @MTZ8302 's ESP dual antenna code, and so I can take advantage of RTK with the base station I made. But initially to prove the system, I will be using the existing SF3000 unit thats already connected via serial to the tablet.
Got it out field for its first test a few days ago:
This was planting veg at 0.4kph, holds the line just fine, however, I am still trying to get the valve control really sorted. It works well enough, but you can feel it jerk a bit in the cab as it makes corrections.
I am finding the valve varys alot at which point is starts to move, based on coil temp etc, which makes it tricky to setup so its always smooth, as the min PWM point (where its smooth) can move 5-6 pwm in a matter of minutes… I think a smaller valve would likely hide alot of the problems, but I cant seem to find anything suitable (load sensing 5 port proptional valve) other than this (Hydraforce SP10-57C…) Hydraforce also make a SP08 series, which is smaller and much more suitable flow, but only make it in a 58D model, which leaves steering lines open to tank in neutral, which isnt much good!
I am looking into introducing current monitoring on the valve wires, and a PID loop to use closed loop current control on the valve, as current is directly related to movement , unlike PWM which is effected by many things in the coil…ongoing project so will see where this goes, also possibly looking at using an external 12/16bit i2c DAC, to give me some more resolution on the output to aid smooth control…
If anyone has any input on any of these matters id love to here…as said, its working either way, and I guess i should just be happy, but im confident it could be alot better, so will be an interesting project!
So much thanks to @BrianTee_Admin for all his work, and also all his help on here / telegram group, and also all the other members I have been talking to / in discussion with regarding the hydro valve etc…so great to have a community like this, such a cracking project.
Cant wait to get out in the field and do some more fine tuning etc!
Hope it was an interseting read for some!
