ASABE Technical Library - Abstract

Abstract. The determination of yield distribution within a farm field is crucial to more efficient and cost effective precision management. Obtaining yield map data is not an established procedure for most hand-harvested crops. Efforts to produce such data for fruit trees work either at the bin-level, use expensive technology, or require changes in workers’ harvesting activities. We propose to convert the carts used for picking strawberries, which in California represent a 2 billion dollar crop, into affordable and easy to operate yield monitoring devices. A prototype cart was built and instrumented with an Arduino microcontroller, and load cells to measure the weight of the harvested strawberries as the tray filled up with fruits in real-time. Additionally, an attitude and heading reference system (AHRS) was included to compensate the weight when the load cells were tilted. An off-the-shelf GPS module was added to collect location data, as well as a relatively inexpensive real-time kinematic (RTK) GPS module to provide ground truth location data. A field experiment was carried out and as a worker picked and placed the fruits in the cart, the weight data was measured and stored in a solid-state (SD) memory card, along with GPS position data. After harvest, a yield map was generated for an approximately 0.12 ha area plot of the field. Load cell measurements showed a mean absolute percentage error of 2.6% compared to the weights recorded by a digital scale. This error was reduced to 1.6% by employing a correction factor to the load cell data.