In November 2017 we have made the first independent test of FieldBee at Inagro government research centre in Belgium. Inagro is supporting agricultural and horticultural businesses in the areas of innovation and sustainability. Read their report on FieldBee navigation system below. (Original article is here https://leden.inagro.be/Artikel/guid/3702
Alternative GPS system is promising for simple applications
Many farmers see potential in use of RTK-GPS, but they are turned off because of the high-cost and the unknown returns. In early November, eFarmer, a Dutch start-up, came to the Inagro bio farm to present their alternative FieldBee system and to compare it with a commercial RTK-GPS system.
GPS uses satellites in combination with correction signals from reference stations. These reference stations can come from the FLEPOS network that is freely accessible to everyone (in Belgium) or from a dealer network. The position of these reference stations is known exactly and they transmit a correction signal to the GPS receiver on the tractor or machine. When these RTK (Real Time Kinematic) corrections are used, accurate corrections can be made up to 3 cm and this accuracy can also be repeated over time. This is important to make straight tracks, to avoid overlap between operations, to work with fixed tracks or to hoe. Classic RTK-GPS systems consist of an antenna for reception of the satellite and correction signal, a gyroscope to correct the slope, a terminal, and an integrated hydraulic steering module. Depending on the version and the tractor, the total costs 15,000 to 20,000 € for the entire system. Entry-level models for GPS control without RTK correction are much cheaper but are usually only 20 cm accurate. These are sufficient for spraying and spreading fertiliser and can result in savings of up to 10% due to overlap.
eFarmer has developed an RTK-GPS system with a highly simplified and much cheaper approach. The FieldBee (this is their satellite receiver) is installed on the roof of the tractor and wirelessly connects to an app on the smartphone or tablet of the user. They take the RTK correction signal from the FLEPOS network. The cost of this system is a subscription fee of 100 €/year for the application and a one-time purchase of the FieldBee GPS receiver of 600 €. In addition, the user must have mobile internet on his smartphone or tablet to make the connection with FLEPOS (normal consumption estimated at 300 to 500 Mb per month). In comparison with classic entry-level models for GPS control, this is a lot cheaper. The FieldBee still has no autopilot. It needs to be manually controlled in the direction the FieldBee app shows on the screen of the smartphone or tablet. But it can be upgraded to the automatic steering, an external control module that is currently being developed for this purpose.
The FieldBee antenna is simply placed on the roof of the tractor with a magnet. The software is user-friendly and easy to install on the tablet or smartphone. No additional wiring was required for the installation. At the start of the test, the system needed a few minutes to achieve RTK precision. eFarmer indicates that the coverage of the FLEPOS antennas is not perfect everywhere. If the closest antenna is at some distance, it may take some time for the system to stabilise. Once the system stabilised, an average accuracy of less than 5 cm could be maintained during the test without additional correction. For this, several times the same paths were driven. We saw an average accuracy of less than 4 cm with a standard deviation of 2 cm and a maximum deviation of 10 cm.
If necessary, an additional accuracy (0-4 cm) can be obtained by using a base station (cost € 1100). This fixed station will amplify the correction signals and send them to the receiver on the tractor.
Possibilities and limits
The system is certainly suitable for rough GPS work (eg tillage, fertiliser spreading, splitting plot, …) and is an alternative to be considered here for the classic entry models. Keep in mind that you always have to have your smartphone or tablet on the tractor. The system also appears to be of interest to smaller companies that work on beds and are now ‘driving in rail’. Because inaccuracies do not accumulate, the system probably keeps the beds to a sufficient extent during the preparatory fieldwork.
For the time being, the FieldBee is still insufficiently accurate for precision work (eg straight driving, hoeing, fixed tracks, …) but could also be used for this with an extra base station. A disadvantage of the system is the lack of tilt compensation, which means that inaccuracies can occur on steeply sloping plots or at high speeds on rough terrain. It is also not yet possible to make the connection with automatic steering units on the tractor or machines, with section control or with machines that allow variable dosing. eFarmer has the ambition to develop these applications in the future. In the short term, the classic RTK-GPS systems for these applications remain a must.
Do you want to know more? On Thursday, December 14 from 11 to 15 hours, a FieldBee demonstration will be organised at the Proefhoeve Bottelare (Diepestraat 1, 9820 Merelbeke). You can register via firstname.lastname@example.org
Do you want to know more about precision agriculture? Contact Jonathan Van Beek, email@example.com