| Impact bruising of apples during harvesting, handling, and transportation, results in major damage and quality loss. A data acquisition system which can be configured as an instrumented sphere (IS) has been developed which permits automatic impact measurement and recording of vector accelerations along with the time of occurrence. The features of this device are as follows: (1) The data acquisition device is a miniaturized, totally integrated, portable, stand-alone system which can fit in a 15 cm cube. (2) The IS is calibrated to provide an accuracy of (+OR-)4.35 g over its full range in the measurement of impact experienced by fruit.; The present IS consists of a 15-cm cube containing a triaxial accelerometer, a NMOS 8097 micro-controller chip with A/D on board, 64 kbytes of RAM, a real time clock, and a rechargable power supply. The 8097 NMOS chip will be replaced by a CMOS version when this becomes available. A connector for serial communication is provided to permit program initialization and data transfer to an independent computer.; Impacts were applied simultaneously to Ida-Red apples and to the IS mounted on an impact table. Data were collected to relate the measured impacts and corresponding bruising. A predictive model was obtained by step-wise multiple linear regression which predicted bruise diameter to (+OR-)3 mm with 99 percent confidence. The model could account for 90.2 percent of the bruise diameter variations about the mean. This model was compared with both the Hertz theory and plastic theory, which at best could only account for 65.6 and 66.2 percent of the bruise diameter variation about the mean, respectively. An adjusted Hertz theory was developed which predicted 86.9 percent of the bruise diameter variation.; The IS data acquisition system appears to meet the design criteria. When further developed it should provide insight into bruise prediction and bruise prevention for fruits, vegetables, and damage reduction for fragile non-food articles. |
