System makes precision farming practical

DN Staff

March 4, 1996

4 Min Read
System makes precision farming practical

Minnetonka, MN--Until recently, farmers applied agricultural chemicals to fields pretty uniformly--the entire field got the same dose, so to speak. Site-specific farming aims at changing all that. This technique seeks to maximize agricultural yield by spreading only the inputs (fertilizer, herbicide, etc.) actually needed by plants in a given part of a field. As soil characteristics vary in the field, so does the application of products to the field. In addition to improving yields, site-specific farming should enhance the environment, because farmers will use chemicals only where they must.

Users prepare for site-specific farming by establishing a grid in their fields and then sampling the soil in each grid. This information gets reduced to a digitized map. After consulting with an agronomist, the farmer then decides what products he needs to apply to the different soils in the field.

Robert Monson and his colleagues at Ag-Chem Equipment Co., Inc., have teamed up with engineers at Soil Teq, Inc., an Ag-Chem subsidiary, to develop hardware and software designed to make precision farming possible. The SOILECTION(TM) system's multi-bin application equipment allows users to spread as many as nine different products on a field simultaneously. Controlling this application process, and placing the products where they need to go in a field, requires an in-vehicle networking system and GPS information.

The Fertilizer Applicator Local Control Operating Network (FALCON(TM)) governs the company's SOILECTION spreader systems. A distributed network, FALCON is based on Motorola's Echelon chip. Each Echelon chip contains three microprocessors, two of which handle transmissions and communications on the network. The third processor carries out control system functions. All nodes are programmed in Neuron C(R), an Echelon proprietary language.

System commands originate with a cab-mounted host PC based on a 486-Series, 33 MHz microprocessor. It employs an Echelon Application Programming Interface (API) to communicate on the network--typically via a serial port or backplane. An industrial-grade system, the host comes with a mouse incorporated into the keyboard and an active matrix display. At each node on the network, the Echelon chip controls application using a metering system and a feedback device.

Each of these controlled points on the spreader represents a control loop. Because each node operates its control loop independently of the others, the overall system is quite robust and--most important--consistent. Firmware needed to operate each node remains resident in the node until it's loaded and executed at the node. It can be enhanced by downloading from the host system into an EEPROM on the node board.

Monson and his colleagues use Windows(TM) as an operator interface. However, Windows inherently cannot guarantee when any event will occur in a Windows application. Consequently all time-based control requirements reside on the network, rather than at the host.

To provide location data to the FALCON control system, the Ag-Chem engineering team entered into a partnership with engineers at Loral Defense Systems, Eagan, MN, to develop a proprietary GPS system called AgNav(TM). To use AgNav, the farmer goes to an external landmark, and synchronizes the GPS system to that location. From that point, as the farmer drives through the field, the host can track the vehicle's position within n3m and display a vehicle icon on 200-color maps--in real-time. These maps show the machine's location and the actual area spread. As the machine traverses the field, the FALCON control system uses map data to determine the proper formula to apply to each part of the field.

By employing a patented Ag-Chem process, users can load more than one map into the host from floppy disks, and the host can then stack the maps. These maps might contain information on areas that need a specific type of nutrient or herbicide. Maps can also be presented in a tiled format to cover larger areas. On the host's screen, the machine operator can see the digital map of the field, vehicle velocity, product bin status, and other pertinent spread data.

The SOILECTION application system isn't simply a new way to do an old job, according to Monson. "It will change the farming arts into farming sciences," he asserts.

Additional details...Contact Robert J. Monson, Ag-Chem Equipment Co., Inc., 5720 Smetana Dr., Minnetonka, MN 55343, (612) 933-9006.

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