What does 2.5 cm accuracy actually mean in agricultural navigation?
This is one of the most frequently asked questions by farmers buying agricultural navigation. Does a tractor with an automatic guidance system always drive with a 2.5 cm deviation? And why do two machines with the same navigation drive with slightly different accuracy? It's worth clarifying this issue because GNSS positioning accuracy and actual accuracy are not exactly the same.
Where does RTK accuracy come from?
The receiver on the tractor's roof determines the machine's position based on signals coming from satellite systems. For many field tasks, this accuracy is sufficient, but in precision farming, we need much higher accuracy, which the RTK signal provides. It uses correction data that allows precise determination of the machine's position. Our PWL NanoSteer 210 system, using the RTK signal, provides accuracy up to 2.5 cm.
Does 2.5 cm always mean the same accuracy?
Not exactly. The accuracy of the positioning system isn’t the only factor that determines how precisely our tractor moves. Navigation first has to determine the machine's position, then set the width of the driving path, and finally properly control the steering system.
The actual accuracy of the pass can be affected by things like:
- the quality and stability of RTK
- proper system calibration
- play in the steering system
- driving speed
- bumps and slopes in the terrain
- antenna placement
- type of machine
What about play in an older tractor?
This is especially interesting for owners of older tractors.
As it's already known, the navigation system isn't just for the newest tractors. It can be installed on any tractor with power steering. You have to remember that the navigation system controls the actual steering mechanism. So if there's a lot of play between the steering wheel and the response of the front wheels, the system has to compensate for it. The better the technical condition of the steering system, the easier it is to achieve stable handling.
Does speed affect accuracy?
At higher speeds, the system has less time to make steering corrections. Every turn of the wheel changes the position of the machine. On the other hand, at very low speeds, the system has to determine the driving direction and the tractor's reaction extremely precisely, even with minimal movement. That's why the NanoSteer system doesn't rely solely on precise GPS. It's a combination of GNSS positioning, RTK correction, sensors, and a well-calibrated steering system.
What level of navigation accuracy is good?
Of course, the higher the better, but not all fieldwork needs millimeter precision. For some tasks, a difference of a few or several centimeters might not matter much. However, the more precision a task requires, the more value accurate automatic guidance provides. That’s why, when choosing agricultural navigation, it’s worth looking beyond just one number listed in the specs. The best way is to test in practice how the navigation setup handles the terrain and whether the accuracy is really as stated in the device description.
The whole system matters, meaning positioning accuracy, guidance stability, terrain compensation, proper calibration, and the way the navigation actually controls the tractor.