| Rail safety is an important factor that affects driving security in railway transportation. To monitor it effectively is a prerequisite to ensure the security and patency of railway. Wireless Sensor Network is composed of a large number of sensor nodes that deployed in monitoring areas in a self-organization topology structure, those nodes are able to collect and transmit the information of monitoring objects within the coverage area collaboratively. As the data communication centre between the wireless sensor network and the external network, wireless sensor network gateway is responsible for data aggregation, processing and forwarding tasks and is a key component of the entire sensor monitoring system. Based on the background of wireless sensor network technology, the wireless sensor network gateway used in rail monitoring system is designed for the requirement of rail safety monitoring, and the major work undertaken are as follows:Aiming at the hardware requirements of wireless sensor network gateway, the core processor module, sink module which faces the wireless sensor network, data communication module that faces the external network and power supply unit module are selected and designed. The block diagram and mechanical structure diagram are designed, and the platform of gateway hardware is developed.According to the data control software functions of gateway, serial and internet data communication interface parts are designed, the communication protocols for two different networks are developed respectively and the protocol-conversion is realized. The performance of application software is optimized in respect of data transmission integrity and data forwarding efficiency, in addition, a remote upgrade method for application software is designed and implemented.Aiming at the specific requirements of site commissioning for rail monitoring sensor network, a type of gateway for site commissioning is developed. Structure and composition of its hardware are designed. Online debugging software applied to the host computer is developed, which could realize multi-node monitoring, node parameters setting as well as the update of nodes’software, is convenient for technicians to manage quick commissioning and maintenance in work site.The WSN remote monitoring gateway and site commission gateway are applied in some rail stress monitoring system for long-term test. The results show that:the WSN gateway hardware platform and its application software could meet the basic requirements of outdoor work, the effective communication distance between gateway and node is more than200meters and the data transfer performance is favorable. The data control software is stable with a low data loss rate and is good in real-time performance. The WSN gateway has important practical significance for the using of wireless sensor network in rail safety monitoring system. |
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