Prototype of Automatic Calibration System Based on IoT for Weights Using Conveyor Scale

Calibration of weight standards aims to ensure the accuracy and traceability of measurement results. In Indonesia, manual calibration of weight standards is still commonly used, which comes with risks such as the potential for weights to fall during the transfer process, damaging their physical and metrological characteristics. Additionally, large falling weights can injure calibration personnel. This study developed a prototype of an automated Internet of Things (IoT)-based calibration system using a conveyor scale. The prototype follows the calibration method outlined in OIML R 111-1: 2004. The system is equipped with BME280 sensor to read temperature, humidity, and air pressure to monitor environmental conditions. The system automatically records calibration data and environmental conditions to Google Sheets. Accuracy tests confirmed that the BME280 sensor is functioning properly. Reliability tests showed that it provided stable readings over an hour at different points. The conveyor scale can measure weights from 20 to 600 g, with a resolution of 0.1 g and a maximum error of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 1$</tex> g. Linearity tests indicated that the scale readings are very consistent, and repeatability tests showed a standard deviation of 0.4 g. The maximum differences from the eccentricity test were 0.1 g for dynamic measurements and 0.2 g for static measurements.