The calibration of weights aims to ensure the accuracy and traceability of measurement results. Currently, manual calibration of weights is still commonly performed, although it carries the risk of the weights falling during the transfer process. High demand also demands faster calibration completion time. Several studies have developed automatic calibration systems to reduce operator involvement. The systems developed include a movable table with an electric motor for calibrating weights ranging from 200 kg to 1000 kg, as well as a 3-axis robot system for 20 kg weights. Although effective, these systems are not capable of accommodating various dimensions of calibration weights and require high costs. Recent research has produced an automatic mass comparator for sub-milligram calibration weights of various shapes.
Based on these studies, the author has developed a prototype of an automatic calibration system based on the Internet of Things (IoT) using a conveyor scale. This system is equipped with temperature, humidity, and air pressure sensors, and is capable of automatically recording calibration data and environmental conditions to Google Sheets. The prototype uses a calibration method according to OIML R 111-1: 2004 with an STS weighing scheme. The resulting conveyor scale has good linearity with a measuring range of 20 g to 600 g. The scale readings show consistency with a standard deviation of 0.4 g and a maximum value of dynamic and static eccentricity differences of 0.1 g and 0.2 g. This prototype has been proven to reduce the standard deviation and calibration time by up to 52%. Data obtained from the calibration of 3 different shapes of calibration weights indicate that the shape differences do not affect the calibration process using this prototype.
Keyword: automation, calibration, conveyor scale, internet of things, weights