Ag thoughts required for an automotive RTK product

BenM

Member
I work in automotive testing using GPS and wanted some thoughts on using some of our equipment in the agricultural area especially for RTK correction. My local farmer friend spends a fortune with John Deere and I think I may help him save some money. So I have a 10Hz RTK GPS receiver unit with a built in modem (data sim required) with a CAN and RS232 serial output and positional accuracy <2cm. This is happy to conect to pretty much all the regular RTK correction services and also NTRIP services provided through the SNIP software program. Where I need technical help is whether this would be suitable to replace a Starfire3 or indeed work with the JD system, how it would be connected etc.etc. Obviously the local JD man is not very helpful so I thought I would put a note on here to see what your collective thoughts are. This item is about £2000 depending on exactly what is required. If you want to see more about it search for VBOX Sigma using your favorite search engine. Thanks in advance.
 
Location
North
Competition is always welcome. Is that an auto-steer ready JD tractor that you are considering with the idea to replace the JD dome with a third party GNSS receiver? I wish you luck. No personal knowledge there but I'm sure JD has had more effort to excluded third party receivers than they've had implementing their system as such. :)

The VBOX specs were not complete or clear. Does the device include a gyro unit? Looks like a 200€ u-blox receiver with a cellular modem add-on board (u-blox provides those too).

You should refer your ideas to the AgOpenGPS approach (use your favourite search engine to find more). There we do the whole system at less than £1000, including the base, the screen and the steering system.

Many low cost commercial systems exits too, don't want to give names as I would forget many. You can find those too from this forum.
 

BenM

Member
Competition is always welcome. Is that an auto-steer ready JD tractor that you are considering with the idea to replace the JD dome with a third party GNSS receiver? I wish you luck. No personal knowledge there but I'm sure JD has had more effort to excluded third party receivers than they've had implementing their system as such. :)

The VBOX specs were not complete or clear. Does the device include a gyro unit? Looks like a 200€ u-blox receiver with a cellular modem add-on board (u-blox provides those too).

You should refer your ideas to the AgOpenGPS approach (use your favourite search engine to find more). There we do the whole system at less than £1000, including the base, the screen and the steering system.

Many low cost commercial systems exits too, don't want to give names as I would forget many. You can find those too from this forum.
Thank you for your reply. What I am trying to do is figure out whether the Sigma might be suitable to help my farming friend. I do not know about tractors but I do know about GPS.
I detect a slight agressive posture in a few of your comments! The Sigma spec is clear and is complete. If it had an IMU it would say so! I had a look at the AgopenGPS. The software looks useful but who am I to know? I am on here to find out what farmers do and want. But all the hardware pictures look like home made projects unless I am missing something? I am sure I will learn more in due course!
 
Location
North
I detect some aggressive posture in your comments (sorry if you did not like me quoting your text). You are the expert of the product, can you explain if heading is "only" NMEA VTG? I cannot remember any NMEA sentence providing longitudinal and lateral acceleration but it may just be that I've never used them.

On Ag applications the accurate position is not enough, we usually need tilt compensation and gyros too for higher performance, specifically at RTK accuracy.

You are right, AgOpenGPS is intended for DIY farmers. We most often do not have the £2000 for a GNSS receiver and buy a 200€ product and put it to a box of our own. The hardware is simple, the heart of AgOpenGPS is the software that a few geniuses have built and offer farmers for free.

Anyway, nothing here is really an apples-to-apples comparison. I'd be happy to see this VBOX Sigma in a complete precision Ag application to be able to compare it with a few DIY like products as well as low cost commercial products. I don't consider it competing with OEM products but I'd like to be wrong.
 

# Robin

Member
Location
Kent
I get your idea as your vbox has a receiver/correction and sends position signal … but to be honest I’m not sure it helps.

How I see it: Autosteer system comprise receiver and steer-control ecu. JD these are combined within the dome, others are separate.
Receiver sees satellites and can get a correction feed (base station / subscription signal).
Ecu uses the position data and internal accelerometer for heading to create steer curvature. It can send that on CAN or pwm a hydraulic valve.

id have thought could pick up a stand-alone receiver cheaper than your vbox if you want to play
 

BenM

Member
Thank you both for your responses. This is the kind of information I am looking for. Northern Farmer. Our channels are not taken from the NMEA messages. Please see here for a full explanation: https://en.racelogic.support/VBOX_A...nformation/Knowledge_Base/Channel_Definitions
I understand the desire for DIY products and indeed have made my own basestation which works with some but not all RTK enabled GPS engines. If the steer ECU is in the dome, this may prevent much further investigation. When JD enable RTK in their dome, is this a firmware upgrade or do they replace the dome with a new one with an RTK GPS engine?
 
Heya Ben - any chance you are interested in plodding some of the that tech inside an automated ploughing/sowing/weeding robot(s)? Open source obv, targeting "low return on labour"/"small holdings" farmers in India.... hopefully we can develop some findings that are transferable to UK farms as well (obv source is global!)

I'll draw up the cad designs cover the prototype costs, build up a large sample size of datapoints etc. Happy to work on the instruction docs together and load to GitHub/Open Source communities collectively.

I'll be working a few projects like this full time from May'22 onwards. Drop me a pm if your interested in figuring something out, if not - no worries. It's a bit of a weird one I know!
 

Adeptandy

Member
Arable Farmer
Location
PE15
Biggest problem with gps and mobile sims is connection in rural settings. The guys sorting mine are having a right headache with drop outs. I seem to be in a black hole for sim data. Nothing they can do about poor network coverage even when running multi network sim.
No way you’d run robots here currently.
 

BenM

Member
To get good RTK you must have a good number of satellites as well as 4G. Galilleo are exceptional in their resiliance particularly E5 frequency. And try EE data sim if you have not already done so. They seem better than most in my experience. I have never found multi sim to be advantageous in this country.
 

Adeptandy

Member
Arable Farmer
Location
PE15
To get good RTK you must have a good number of satellites as well as 4G. Galilleo are exceptional in their resiliance particularly E5 frequency. And try EE data sim if you have not already done so. They seem better than most in my experience. I have never found multi sim to be advantageous in this country.
Plenty of satellites, its the 4g that's lacking, tried all networks, even had 3 different sims connected the other day and it still kept dropping.
 

BenM

Member
If your area is fairly flat and not too large, you might get away using radio. Satel Easyline is my preferred choice. If you need to use repeaters, this could get quite expensive.
 

Adeptandy

Member
Arable Farmer
Location
PE15
If your area is fairly flat and not too large, you might get away using radio. Satel Easyline is my preferred choice. If you need to use repeaters, this could get quite expensive.
IMG_9943.jpg


Its that flat ;)
 

clbarclay

Member
Location
Worcestershire
And they can't get decent phone signal over that??

I have heard of people using mobile relays which get the correction data over the mobile network and broadcast it to the tractor receiver using low powered radio. However I thing that was more suited to hilly terrain where the relay can be placed on a nearby hill that can see the mobile network and broadcast to the field in a valley that is a mobile black spot.

I recall that one off the UK farmers using AgOpen has set up a wifi network around much of his farm.
 

Lofty

Member
Location
Worcs
I work in automotive testing using GPS and wanted some thoughts on using some of our equipment in the agricultural area especially for RTK correction. My local farmer friend spends a fortune with John Deere and I think I may help him save some money. So I have a 10Hz RTK GPS receiver unit with a built in modem (data sim required) with a CAN and RS232 serial output and positional accuracy <2cm. This is happy to conect to pretty much all the regular RTK correction services and also NTRIP services provided through the SNIP software program. Where I need technical help is whether this would be suitable to replace a Starfire3 or indeed work with the JD system, how it would be connected etc.etc. Obviously the local JD man is not very helpful so I thought I would put a note on here to see what your collective thoughts are. This item is about £2000 depending on exactly what is required. If you want to see more about it search for VBOX Sigma using your favorite search engine. Thanks in advance.
Starfire receivers communicate with the tractors steering controller via CANbus so the first problem is getting your reciever to talk the right JD language. Second problem is the the Starfire has inbuilt terrain compensation (yaw/roll) so your going to have to replicate that without the Starfire on the roof.
HTH
 

BenM

Member
Thanks Lofty. Thats useful information. My unit outputs position, heading etc. via configurable CAN messages so that should not be a problem. It is this element that is quite expensive if purchased via JD. Assuming JD are measuring pitch, roll and Yaw rate (rather than calculating it) those values should be I guess on the CAN bus for steering control to use. Its also possible that JD are integrating GPS and IMU together to improve the accuracy and robustness of the position and heading values as is the case in some of the equipment that I sell. I realise that this is all quite a long shot but if you don't try..... etc. And I am learning a bit more about the ag industry every day!
 

# Robin

Member
Location
Kent
No I think the autosteer ecu is making the curvature calculation itself using those inputs and based on deviation from wayline. On a CAN steer valve tractor it’s the sending 1939 protocol curvature message for the steervalve to pwm it’s proportional valves.
But Deere could well be proprietary message from dome to steer valve you’d have to sniff the bus.
Not sure how the waylines are stored either

Think hardware architecture of combining ecu into the receiver is more a commercial one

Probably be easier to pull a Deere dome apart and fit your Receiver inside of your wanting to bypass that aspect?
 

Dave645

Member
Plenty of satellites, its the 4g that's lacking, tried all networks, even had 3 different sims connected the other day and it still kept dropping.
Fieldbee base stations have a 2.5km Range radio mode, zero drops and full RTK. You do have to have fieldbee receivers that can use the radio mode.
The base station can also be setup in the field it has a good battery life, the only difference is repeatability, you can remove that problem with fixed locations as in fixed masts that you reuse, and the base station has a memory for locations so you just set it, once save and name the location and just reuse it when you reuse that mast location.
You don’t even need a SIM card if your using fieldbee stuff on the tractor.
it also can do it via SIM cards and has a 25km range, but as you said then your relying on mobile phone data signals, which in trees and in dead spots can be patchy.
I think mine was about £1000 for the base station they don’t tend to discount it.

as far as ongoing cost with fieldbee the app has a subscription of about £100 per year.

I am happy with mine.
 

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