|Yu, P -|
|Li, C -|
|Krewers, G -|
|Rains, G -|
|Hamrita, T -|
Submitted to: Computers and Electronics in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 8, 2013
Publication Date: January 28, 2014
Citation: Yu, P., Li, C., Takeda, F., Krewers, G., Rains, G., Hamrita, T. 2014. Evaluation of rotary, slapper, and sway blueberry mechanical harvesters for potential fruit impact points using a miniature instrumented sphere. Computers and Electronics in Agriculture. 101:84-92. Interpretive Summary: The majority of the highbush blueberries in the United States are still hand-harvested because current mechanical harvesters create excessive bruise damage to the fruit. The development of sensing tools for quantitative evaluation of the blueberry harvesters can assist in refining the mechanical harvesting technology. A miniature, spherical instrumented sphere was built to quantitatively evaluate harvesters with a rotary, slapper, and sway mechanism for harvesting blueberries. The results indicated that the slapper and sway harvesters generated larger number of impacts and more severe impact to the fruit than the rotary harvester. The disparities in impact numbers and magnitude among the three harvesters were due to longer agitating periods, more violent shaking action, and higher drop distance between the conveyor belt and the collection box for the slapper and sway harvesters. The distribution of the impacts showed that 90 percent of all impacts were less than 190 g in the rotary and less than 250 g in the slapper and sway harvesters. These findings also suggested that the cumulative effects of high number of small impacts should not be ignored. The impact recording device located the impact points during the harvesting process in the rotary, slapper, and sway harvesters that could be used to improve the current mechanical harvesting technology.
Technical Abstract: Blueberry production in the United States has expanded to more than 63,000 acres, a 55 percent increase over the past decade. Blueberries are prone to bruise damages and the vast majority of the fruit destined for the fresh market is hand-harvested. Bruising leads to a rapid increase in the amount of decay. Hand-harvesting is labor intensive and costly. Recent changes in labor laws in many states are expected to create a major crisis in the fresh blueberry industry. The industry needs machine-harvestable fruit with fresh market quality to reduce harvest cost and improve production efficiency. The susceptibility of different highbush blueberry genotypes to bruise damages is usually evaluated by dropping the fruit from certain heights and assessing for tissue discoloration afterwards. In this study, the bruise susceptibility of three crisp-flesh and one conventional-flesh highbush blueberry genotypes was correlated with the data recorded by a berry impact recording device (BIRD) by dropping both the fruit and the BIRD sensor onto two types of contacting surfaces (hard plastic and cushioning material). The drop test confirmed that a conventional-flesh genotype (‘Scintilla’) was more susceptible to bruising than the semi-crisp or crisp-flesh genotypes (‘Farthing’, ‘Sweetcrisp’, and ‘FL 05-528’). Selection ‘FL 05-528’ was proven to be a promising machine harvestable genotype in terms of the resistance to bruising. Using both the impact and velocity change, we established bruising probability lines for each of the four highbush genotypes. This was useful in transforming the impact data recorded by the BIRD sensor into bruising probability of a blueberry genotype. The result of this study will provide decision support for blueberry farmers and breeders for selection of machine harvestable highbush blueberry genotypes. The correlation between the blueberry bruising incidents and BIRD data will help better interpret the impact data which can be used to improve blueberry mechanical harvesting technologies.