Characterisation of a Potato-shaped Instrumented Device

Instrumented spheres are used worldwide in food processing chains to locate bruising risk zones and to prevent quality loss of commodity. Risk zone location and optimisation of machine settings can be executed with a satisfying accuracy by comparing test results mutually, but measurement data are often hard to interpret, especially if predictions are desired on real damage. An extensive knowledge of the instrumented device and indications on the bruise susceptibility of a product are two indispensable conditions for successful damage prevention and reduction. As data acquisition techniques become more sophisticated and the autonomy of the measurement equipment tends to be better, the new generation of electronic potatoes, such as the Danish made PTR 200, seems promising for bruise prevention purposes. This is mainly due to improved memory capacity and more accurate data acquisition techniques. The main topic of this research was to determine the properties of the recently developed tool PTR 200 and to expand the knowledge of the device for a good use in practice. The research work was focussed on four important device characteristics: (1) the sensitivity of sensor zones; (2) the impact force—signal output relationship; (3) the consistency and reproducibility of measuring results; and (4) the signal transmission range. Under laboratory conditions, the sensitivity of sensor zones, the relationship between impact force and signal output, and the consistency and the reproducibility of measuring results were examined. One on-field procedure was executed to determine the signal transmission range. Laboratory characterisations were conducted with a pendulum impactor and revealed a varying impact force on 22 impact zones in case of application of an equal energy amount of 0·3525 J. A distinct relationship was found between impact force and signal response. Measurement results were consistent and reproducible; high standard deviations emphasise the importance of repetitive measurements to obtain relevant mean values. The maximum signal transmission range was identified as between 10 and 15 m. However, if there was an obstacle between the receiver and the transmitter the signal was immediately lost.