A Novel Self-Powered Wireless Rollers' Rotational Speed Monitoring System

In this article, a novel energy harvesting-based, self-powered wireless speed monitoring system has been developed for monitoring the rotational speed of rollers without any modifications to existing rollers and conveyor systems. This innovative solution comprises multiple wireless sensor nodes, a Zigbee coordinator, a 4G module, and an Ali Cloud Computing-based visualization interface. Each compact wireless sensor node is housed within a 68× 52× 25 mm plastic box. It is equipped with an energy harvester, a power management unit, and a wireless sensing module. The energy harvester converts the rollers' kinetic energy into electrical energy. A comprehensive transient model has been developed to precisely predict the harvester's performance. The power management unit ensures reliable rectification, storage, and regulation of the electrical power generated. The optimized energy harvester achieves an output power of 23.5 mW at 800 and 1.8 mW at 100 r/min. Under laboratory conditions, the energy harvester can charge a 0.1-F supercapacitor to 5 V in 85 s at 600 r/min, corresponding to a power level of 14.7 mW. The wireless sensing module collects speed information from rollers and transmits it to a base station connected to the cloud via a 4G telecommunication network. Ultimately, the real-time rotational speeds of all rollers are visualized using a custom-designed user interface. Finally, the effectiveness of the self-powered wireless roller speed monitoring system is successfully demonstrated in a test bed.