Research On Monitoring Bridges And Tunnels Runthrough Earth Cables Based On GSM And ZigBee Technology

ABSTRACT:Railway runthrough earth cables as the comprehensive earth cables of safety, shield and lightning, has been widely laid along each railway. However, due to the railway special runthrough earth cables are mainly made of copper wire with metal alloy or polymer material sheath, making it easily be stolen or damaged in tunnels or bridges where the cables can’t be buried. Once the railway runthrough earth cables got lost or damaged, it would lead great threats to the safety of railway traffic and workers. Therefore, it’s urgent to develop a runthrough earth cables’monitoring system, when the earth cables get lost or damaged, which could completes the functions of alarming and information transferring centralized, in order to facilitate the protection and maintenance workers’detecting and repairing the cables, thus to ensure the safety of train traffic.Given all of the above, firstly, the paper analyze defects of the existing monitoring schemes. Then, according to the rapid development of ZigBee and GSM technology as well as their applications in engineering monitoring, designs the runthrough earth cables single-point monitoring system based on GSM technology, and further develops the runthrough earth cables regional monitoring system based on ZigBee and GSM technology.The paper focuses on the single-point monitoring system’s design. After the determining of the overall scheme of the monitoring system, the author completes the system’s outdoor and indoor hardware design, software design, and low-power design. The single-point monitoring system software design is developed with C language on the platform of Keil uvison4, the hardware design is developed on the platform of Protel99SE, the low-power design includes the hardware low-power design and the software low-power design.The single-point monitoring system’s indoor simulation test and railway site actual test results show that the monitoring system could realize long-distance, real-time, stable monitoring on the runthrough earth cables’current and mechanical integrity status through ways of current and mechanical monitor at a bridge or tunnel. And it is suitable for long-term and long-distance monitoring with accurate measurement and low-power consumption.As to the regional monitoring system, after the determining of the overall scheme of the monitoring system, the author completes the system outdoor unit’s hardware configuration and software debugging, the system indoor unit’s hardware configuration and software design. Besides, the simulation optimization of ZigBee routing protocol is made. The regional monitoring system’s indoor simulation test results show that the system could realize real-time, remote region monitoring on a bridge or tunnel railroad equipments’ current status, including the runthrough earth cables.Finally, the paper summarizes and outlooks the two kinds of designed monitoring systems. The single-point monitoring system that requires to achieve one point to multi-point’s monitoring ultimately, which means one indoor unit to achieve real-time, remote monitoring of multiple bridges or tunnels’ runthrough earth cables. The regional monitoring system that requires to achieve self-development of the the outdoor unit software and hardware.