Application Spotlight: Force Sensor-based Grain Flow Sensor for Combine Harvesters

An automated monitoring system to measure the volume and weight of grain harvested in a specific area.

The challenge

Today’s farmers need advanced technologies to help them maximize production while minimizing resource consumption. For example, small changes in crop yield can indicate that the soil in a specific area is low in nutrients and needs extra fertilizer. Identifying those changes in real time can help farmers pinpoint areas that need fertilization to maximize crop growth. To achieve this, farmers need an effective way to accurately measure crop yield by specific area in real time.

The solution: A force sensor transducer designed for agriculture

In partnership with a distributor, VPG Transducers designed a solution that monitors the flow of grain into a combine harvester by measuring the force of the grain as it enters the grain lifter arm.

The solution is based on a heavily modified version of the Tedea-Huntleigh Model 355 Single-Ended Shear Beam force sensor. The Model 355’s remarkable design incorporates a bellows section into the main body of the force sensor. This provides additional protection to the strain gauges within the cell and makes the entire force sensor more flexible, reducing wear and tear.

An ordinary Model 355 is made entirely of stainless steel and is welded together to provide a hermetic seal. In this version, the stainless-steel bellows are replaced with rubber bellows to prevent grain from becoming trapped inside, as even a single seed can affect the accuracy of the load cell. Additionally, because a standard polyurethane cable would melt in the high temperatures inside the average combine harvester, the grain flow sensor has a far more resistant Teflon cable.

Model 355

To preserve the stability of the load cell while the combine harvester moves, the force sensor is mounted on a Tedea-Huntleigh Self-Aligning Mount within the combine harvester’s grain lifter arm. The Mount is made from the same high-quality stainless steel as the Model 355’s body, ensuring ongoing reliable operation even after a long time in wet, corrosive conditions.

Benefits

Correlating the highly accurate measurements provided by this customized Tedea-Hunteligh Model 355 force sensor module with positional data collected from a GPS unit on the combine enables precise calculation of the yield by farmed area. This innovative Grain Flow Sensor application provides farmers with an indication of yield changes in real time and helps them determine optimal utilization of fertilizers and other critical resources.

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Learn more about force sensor solutions for agriculture applications