Grain Yield Monitor Flow Sensor Accuracy for Simulated Varying Field Slopes

Abstract

Yield monitors have become vital reference tools for grain growers in making informed management decisions in their cropping operations. The cornerstone of a yield monitor system is the mass flow sensor, used to calculate the mass flow rate of clean grain through a combine. This investigation was initiated to examine the influence of varying field slopes (both roll and pitch) on accuracy levels of a mass flow sensor for a commercially available yield monitor system. A laboratory test stand consisting of a combine clean grain elevator mounted on a gimbal fixture was used to simulate varying field slopes normally experienced during field operation of a combine. Results indicated that slope affected mass flow sensor response. Combine pitch had a greater effect than roll on mass flow measurements. While errors were observed during roll tests (-3.45% to 3.46%), they were considered small and were impractical to correct using predictive approaches. Pitch tests generated higher errors (-6.41% to 5.50%) with discernable linear trends indicating that mass flow was underestimated during aft operating conditions and overestimated during forward rotations. This trend suggests gravitational acceleration of the mass flow sensor during combine pitch may cause these errors. The use of a predictive linear model, to correct flow rates for slope, greatly decreased the overall error for the pitch results.