A Pressure Measuring Sphere for monitoring handling of fruit and vegetables

An ''artificial fruit'' was developed to detect damage sources for perishable fruit and vegetables during practical harvesting and handling. This Pressure Measuring Sphere (PMS) is designed robustly in order to tolerate usual mechanical loads under practical conditions. It consists of a liquid-filled rubber ball with a pressure data acquisition system embedded inside. The system contains a stand-alone microcomputer, a fluid pressure sensing unit and a battery. The PMS is capable to collect all load events touching its skin, if they exceed a preset threshold, and to store them together with time from an internal clock. Calibration tests confirmed that the PMS senses static as well as dynamic mechanical loads. Measured load data were nearly reproducible under static load conditions (variation coefficient about 4%). Under dynamic load conditions a minimum of 15 measuring runs provide for representative results (variation coefficient about 20%).