GPS Precision Farming Accuracy

[Indian Territory]

I just asked this question on Reddit, but I probably should have come here first.

We're just a little berry farm using mostly mechanical tractors. Not a lot of electro hydraulic luxury, never mind computer controlled technology. What kind of accuracy do the big operators get with their gps precision farming setups. I mean my phone can't get within 10 feet of being right, but surely that's not close enough for row planning year after year. We'll never be big enough to need it, but I'm curious anyway.

 

[MapleLeafFarmer]

JD's starfire precision farming system accuracy less than an inch.

 

[Indian Territory]

JD's starfire precision farming system accuracy less than an inch.

Dang. Does that require multiple sensors and triangulation, or does it all happen right in the cab?

 

[deserteagle71]

JD's starfire precision farming system accuracy less than an inch.

Yup. I was watching a YouTube video not long ago...some big farmer in the Midwest with some pretty fancy equipment. His tractor cab looked like it belonged in the space shuttle, with all the screens and computers. Giant John Deere tractor, planting; the guy was not touching the steering wheel. Said the GPS system that came with the tractor was accurate to within one inch in one mile!

At the mines I worked at, they used professional Trimble brand GPS units in the ground engaging equipment. That enabled them to quickly level out a piece of ground so that for all practical purposes it was perfectly level.

 

[fc1]

Dang. Does that require multiple sensors and triangulation, or does it all happen right in the cab?

I believe top accuracy requires a calibrated (=location precisely determined) ground-based beacon in addition to the satellite cloud.

 

[mikester]

You have to look at all the quoted specs, sales people lie all the time - or maybe they don't understand what they are selling. No they just flat out lie to get the sale.

You can find some interesting stuff here

AgOpenGPS

Building designing and developing Agricultural Precision tools

discourse.agopengps.com

 

[oldnslo]

Deere has different levels of accuracy based on the system components. The system used for simple tillage vs planting can vary in accuracy from sub inch to several inches. I believe other companies have the same offering.

I have seen systems where there is GPS receiver on both the planter and tractor. Planter is master and tractor is slave for controlling planter position in rolling sidehill terrain.

I was told cost for high accuracy increases pretty significantly a couple of years ago but with advancing technology that may or may not be true today.

 

[dodge man]

I started using gps as a land surveyor in the early 90’s. The accuracy really hasn’t improved but the number of satellites and software has.

A single unit is almost useless for precision. They say 10 meters (33 feet) is the accuracy of a single unit although it does better usually. For surveying we had two units, a base and a rover. The base was setup on a known point and linked to the rover via a radio link. We still use that method but you can also use a cell phone to dial up corrections from multiple base gps units located throughout the state.

I think most precision ag uses some type of radio or satellite link to send corrections to the tractor. If it’s a high quality setup you can get accuracy of 1 inch. It’s also important to have a fairly clear sky to get this accuracy, as in not a lot of trees or other obstructions.

 

[ArlyA]

I asked a farming family member about this some years ago. He then said, something to the effect "GPS software doesn't do well compensating for tractor wheel slippage on hill sides. I don't like it". Maybe he's changed his mind since. I think I'll be seeing him when we go home for a funeral this spring.

 

[oldnslo]

I asked a farming family member about this some years ago. He then said, something to the effect "GPS software doesn't do well compensating for tractor wheel slippage on hill sides. I don't like it". Maybe he's changed his mind since. I think I'll be seeing him when we go home for a funeral this spring.

The wheel slippage is why they are now putting GPS on planter and tractor so planter is in correct position on sidehills.

 

[LHF2019]

I use GPS. No subscription. 100% more accurate than not using it. Use it for spraying fertilizing some planting and for running cultimulchers on no till ground because you can’t see where you been.

 

[Lineman North Florida]

I also use a Raven GPS system and it allows me to put out fertilizer or spray herbicides and pesticides and be +or- an inch or so, I think they are a very useful tool to minimize wasting expensive chemicals and fertilizers.

 

[dodge man]

Wheel slippage has nothing to do with the gps itself. It might be tied into to the system overall. In other words the computer might get info from gps and the tractor itself.

 

[number two]

And what happens when all this hi-tech stuff breaks down?

 

[zzvyb6]

And what happens when all this hi-tech stuff breaks down?

City folks are going to starve.

 

[LHF2019]

I use GPS. No subscription. 100% more accurate than not using it. Use it for spraying fertilizing some planting and for running cultimulchers on no till ground because you can’t see where you been. View attachment 871751

I will add that it does not compensate for side hills and even going over woodchuck holes makes it think your off. Go under trees and it loses signal then your lines are off. If using for planting I have to plan for that. Leaving the field to refill and come back 30 minutes later the lines have moved and need recalibrated. Those are some of the issues that buying the high tech systems take care of. What I can do now is relax while spreading or spraying. No more looking for wheel tracks questimating if I'm close. Spreader is a 40' spread width and sprayer is 30'. Sit back finger on steering wheel and just drive. Turn at the end and know you are right where you need to be. Also extends my day by working after dark.

 

[Lineman North Florida]

I will add that it does not compensate for side hills and even going over woodchuck holes makes it think your off. Go under trees and it loses signal then your lines are off. If using for planting I have to plan for that. Leaving the field to refill and come back 30 minutes later the lines have moved and need recalibrated. Those are some of the issues that buying the high tech systems take care of. What I can do know is relax while spreading or spraying. No more looking for wheel tracks questimating if I'm close. Spreader is a 40' spread width and sprayer is 30'. Sit back finger on steering wheel and just drive. Turn at the end and know you are right where you need to be. Also extends my day by working after dark.
View attachment 871817

Yep, I call it painting lines, and while it has many more features, painting lines is mostly what I use mine for.

 

[Lineman North Florida]

And what happens when all this hi-tech stuff breaks down?

I go back to doing it the old ways, just because you embrace some new technologies doesn't mean you forget how it was done before.

 

[oldnslo]

Wheel slippage has nothing to do with the gps itself. It might be tied into to the system overall. In other words the computer might get info from gps and the tractor itself.

I believe the concern was sidehill slippage and not wheel spin. The GPS does try to compensate for side hill slide or slippage.

On wheel spin - loosing speed I believe there is also compensation for rate control but not sure if this is GPS or some other speed sensor like radar.

I believe GPS is also used for variable rate control today for seeding, fertilizer application, spraying.

Lots of hi- tech when it works its great, when it doesn’t the work still needs to get done so you go from being a passenger to an actual driver again.

 

[Wood_Butcher_Dav]

I'll chime in on this thread as I work in the AG industry, as the company i work for builds many different sensors for Precision Planters.

Precision planting speed now is usually done by ground speed radar sensor. They also use a hall effect sensor looking at a wheel disk on the planter.

Planting also starts off in the office. There are several different PC software systems that tie all the information together. Each field is mapped using a GPS system.

The field 'prescription' is loaded into the tractors computer that communicates with the planter controller. Once the precision planter is in the field working it can then shut off or change rates to individual rows as it moves through the field. There is also a planter monitor that has seed population, target rates, %skips, %doubles for each row.

Some tractors are also equipped with 'Auto Steer' and auto turn on end row.

Dave