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United States Department of Agriculture

Agricultural Research Service

Research Project: NOVEL PRODUCTION SYSTEMS FOR SMALL FRUITS Title: A miniature instrumented sphere to understand impacts created by mechanical blueberry harvesting

Authors
item Li, Changying -
item Yu, Pengcheng -
item Takeda, Fumiomi
item Krewer, Gerard -

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 16, 2013
Publication Date: August 25, 2013
Citation: Li, C., Yu, P., Takeda, F., Krewer, G. 2013. A miniature instrumented sphere to understand impacts created by mechanical blueberry harvesting. HortTechnology. 23(4):425-429.

Interpretive Summary: The majority of US highbush blueberries for fresh market are hand harvested due to the high bruising damage to fruit caused by the machine harvesters. To reduce the bruising damage, we need to first understand how the machine parts interact with the berry fruit. To address this need, we developed a Smart Berry to mimic a berry fruit and to quantitatively measure mechanical impacts experienced by a real berry during the mechanical harvesting. The Smart Berry recorded impacts using tri-axis accelerometers with a maximum sampling every three milli-second, and measured mechanical impacts occurring in the rotary harvester. The data suggested that the catch plate created the largest single mechanical impacts. Reducing the drop height or padding the surface could be an effective approach to reduce potential bruising damages caused by the catch plates. The findings indicated that the rotary detaching mechanism created significantly less number and lower magnitude of impacts than the slapper mechanism. The Smart Berry proved to be useful in quantitatively measuring the mechanical impacts created by the harvesters. It should be useful in improving the design of the current machine harvesters and can also be used to identify impact points in the blueberry packing house.

Technical Abstract: The majority of US highbush blueberries for fresh market are hand harvested due to the high bruising damage to fruit caused by the machine harvesters. To reduce the bruising damage, we need to first understand how the machine parts interact with the berry fruit. To address this need, we developed a Smart Berry to mimic a berry fruit and to quantitatively measure mechanical impacts experienced by a real berry during the mechanical harvesting. The Smart Berry recorded impacts using tri-axis accelerometers with a maximum sampling frequency of 3 kHz, and plus or minus 500g (g equals gravitational acceleration) sensing range. Calibration tests showed that the maximum error of the measurement was 0.53 percent of the output span. The size of the sensor was only half of that for the current smallest instrumented sphere on the market. Used together with a close-up video, the fully calibrated sensors were used to identify and measure mechanical impacts occurring in the rotary harvester. The data suggested that the catch plate created the largest single mechanical impacts. Reducing the drop height or padding the surface could be effective measures to reduce potential bruising damages caused by the catch plates. The Smart Berry was also utilized to compare harvesters with two different detaching mechanisms. The findings indicated that the rotary detaching mechanism created significantly less number and lower magnitude of impacts than the slapper mechanism (P less than 0.05). The drop tests demonstrated that the impact data recorded by the Smart Berry can be correlated to the bruising rates of two blueberry genotypes. The miniature instrumented sphere developed from this project was proven to be useful in quantitatively measuring the mechanical impacts created by the harvesters. The data could be utilized to improve the design of the current machine harvesters for reduction of the bruising rate of blueberries for the fresh market, and potentially lead to enhanced blueberry production efficiency in the long run.

Last Modified: 11/28/2014
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