Development and Experiment of a Smart Scale to Improve Packaging of Flower Cuttings

The actual quantity of product units in prepacked packages is an issue that concerns both the consumer and the producer. The consumer has the right to expect packages to bear accurate net content information, and the producer aims to pack the specified nominal quantities at minimum cost. Accurate weight-based packing of 'packages labelled by count' necessitate very low 'coefficients of variation (CVs) of unit weight. For agricultural products, with relatively high CVs, the usual weighing methods are therefore not suitable. The present study suggests a methodology that supports the count-to-weight transform of prepacked packages of products with wide variability of characteristics. We developed innovative weighing algorithms to produce 'packages labelled by count' and a prototype of a smart scale. The prototype consists of a digital scale; a controller; and, a visual and sound interface. The algorithms were embedded into the controller to facilitate accurate number of counts in a package. The prototype is able to work in two states: 1) calibration – to calculate the critical weight according to the cultivar and package type; and, 2) weighing – loading cuttings on the scale until the critical weight is reached. An experiment to examine the two states was conducted and the results indicate that in the calibration state, the calibration time increased linearly with the package size. In the weighing state, the average packing time per cutting unit was reduced from 1.2 s per unit for a 10-unit package to 0.2 s per unit for a 50 unit's package. The actual number of units in a package was higher than the nominal number but the variability between the different packages was low indicating that the algorithm, the methodology and the prototype succeeded to decrease the variability but need to be calibrated and refined so that the number of actual units per package will be similar to the nominal number.