Blueberries are an important and profitable crop in the United States. The United States has been the largest producer in the world for the last thirty years. Total blueberry production in the US has increased from 112 million pounds in 1991 to 531 million pounds in 2013 and is still growing every year (USDA, 1993, 2014). However, the blueberry is perishable fruit and can be damaged easily by machines. During harvesting and post-harvest handling, frequent mechanical impacts bruise the berries. Previous research has been conducted on identifying when and where impacts occur and quantifying impact magnitudes by using an instrumented sphere (IS). An IS, also known as a pseudo-fruit, is designed to measure mechanical impacts on agricultural products. The previous ISs were mainly designed for large fruits and vegetables and were unsuitable for usage with small fruits like blueberries due to a significant difference in size and weight. Therefore, we developed a miniature instrumented sphere, known as the Berry Impact Recording Device (BIRD), to measure the impacts on blueberries during harvesting and post-harvesting handling
Yu et al. designed the first generation of the Berry Impact Recording Device (BIRD I) sensing system (figure 1), consisting of a BIRD I sensor, an interface box and PC software [1, 2]. The circuit board of the BIRD I sensor consists of three single-axis accelerometers with ±500 g sensing range in each orthogonal axis, one eight-bit microcontroller, one 128KB memory chip, and other electronic components. The size of the BIRD sensor is 1 inch (25.4 mm) in diameter, similar to a large size blueberry (23 mm). Its weight (14 grams), however, is much greater than that of a normal blueberry (3-4 grams). The sensor has been successfully used in evaluating different types of blueberry machine harvesters [3, 4].
Figure 1: Schematic diagram of the Blueberry Impact Recording Device (BIRD) system. (1) = BIRD I Sensor, (2) = BIRD Interface box, (3) = i-BIRD computer software, (4) = DC Power supply for the interface box.
In order to better simulate a blueberry, the second generation of the Berry Impact Recording Device (BIRD II) was developed. The circuit board and battery of the BIRD II sensor was cast into a 21 mm sphere using silicon rubber (figure 2). The weight of the BIRD II sensor was 6.5 grams, which is 54% less than the BIRD I sensor. “The circuit board of the BIRD II sensor consists of three essential parts: a tri-axis accelerometer, a 1Mb Ferroelectric Random Access Memory (F-RAM) chip, and a microcontroller; and other electronic components.
Figure 2: BIRD II sensor. a) Structure of the sensor. b) Size comparison of penny, BIRD II sensor and BIRD I sensor.
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- Yu, P., et al., Development of the Berry Impact Recording Device sensing system: Hardware design and calibration. Computers and Electronics in Agriculture, 2011. 79(2): p. 103-111.
- Yu, P., et al., Development of the berry impact recording device sensing system: software. Computers and Electronics in Agriculture, 2011. 77(2): p. 195-203.
- Yu, P., et al., Quantitative evaluation of a rotary blueberry mechanical harvester using a miniature instrumented sphere. Computers and Electronics in Agriculture, 2012. 88: p. 25-31.
- Yu, P., et al., Measurement of mechanical impacts created by rotary, slapper, and sway blueberry mechanical harvesters. Computers and Electronics in Agriculture, 2014. 101: p. 84-92.