Tunnel Gauge Detection Study Based On Mobile Laser Scanning

The problems to be solved urgently in urban railway tunnel detection are how to capture the data of the tunnel cross section accurately and efficiently and how to make analyses and applications basd on the collected data. The laser scanning technology is able to solve tunnel gauge detection problems because of the properties of high resolution, high efficiency and high precision detection of special objects.Based on the comprehensive researches of tunnel detection techniques domestically and overseas, the effective cutting and functional improvement on the previous mobile laser scanning system which is developed on a demoboard is conducted in this dissertation. The improved mobile laser scanning system enables to provide the accurate digital information of the underground space, and is suitable for industrial production because of the properties of small size, low energy consumption and high efficiency. The gauge detection system utilizes the STM32 microprocessor as the central processing unit, collects the cross section information by Faro Focus3 D scanner, obtains the mileage information with the help of photoelectric encoder, and samples the real time attitude information by the 2D inclinometer. The system also uses the TTL synchronization method to control the scanning frequency of the laser based on the pulse of the photoelectric encoder. The samples of multiple sensors are processed off-line by the self-developed program based on Matlab, including the noise suppression and compression of the sampled data. The accuracy location of the diseases of tunnels could be obtained by comparing the results of the processed data and the established standard data of the tunnel gauge.The dissertation focuses on the research of the tunnel gauge detection system based on the mobile laser scanning, including designing the specialized circuit of this detection system to replace the previous demo board, designing the power modules supplied for each part of this system, constructing the simulation scenarios for testing, providing detection strategies for the tunnel gauge, preprocessing the sampled data and developing the relative applications. The testing results of the real tunnel in Shanghai Yishan road and the simulation cases evaluate the availability and efficiency of the tunnel gauge detection system, which reaches the expectation of researches.