Solar Wireless Sensor Nodes for Condition Monitoring of Freight Trains

The objective of this work is to present the design and testing of a Wireless Sensor Network, powered by solar energy, to be installed on freight trains with the purpose of performing on-board monitoring operations. A complete Wireless Sensor Network requires a certain number of Wireless Sensor Nodes, installed in significant points of a vehicle, provided with sensors and capable of elaborating raw data, transmitting them via wireless network as synthesis information to an on-board control unit. The on-board control unit periodically communicates the data gathered from different sensors to a ground central control unit through the Internet. Each Wireless Sensor Node needs to be powered independently. To achieve this purpose a small solar panel was used to provide the Wireless Sensor Node with the necessary amount of energy. Integrated circuits were designed for power management, acquisition, elaboration and wireless transmission of data and analyzed in terms of performances and energy consumption. The communication protocol between the Wireless Sensor Node and the control unit was first laboratory-tested and finally the whole system was installed on a real wagon, and on-field tests were conducted for a period of almost one year.