| The last two decades have witnessed the rapid growth of optical fiber sensing technology. As one of optical fiber components, Fiber Bragg Grating (FBG) sensors have been widely applied in sensing fields, such as Weigh-In-Motion (WIM) systems. WIM system has important value in traffic administration, pavement and bridge design, etc. With incomparable merits such as light weight, small size and immunity to electromagnetic interference (EMI), WIM technology based on FBGs has been regarded as the most promising method to replace traditional electric sensing technologies.;In this dissertation, starting from the fundamental theory of FBG sensing, we discuss our research of a portable, high-speed (>15mph) WIM system based on FBG technology. A prototype of the WIM system was designed to capture and record the total weights and the distribution of the weights of vehicles. Specifically, as an important role in this WIM system, a high-speed, multi-channel demodulator is described in detail. The control system and signal analysis are included herein. Based on strain analysis, the sensor heads were designed with Carbon Fiber Laminate Composites (CFLCs) to improve the sensitivity, repeatability and reliability of the WIM system. Software was developed by Visual Basic in .Net platform. This system can be further developed into an advanced vehicle intelligent recognition system.;We also discuss the applications of WIM systems in other fields. One example is monitoring railway systems. This WIM system can be employed to weigh the axle loads of train cars, detect flat wheels and monitor the gaps between Platform Screen Doors (PSDs) and the doors of train cars. Moreover, such a high speed demodulator can be combined with a Photonic Crystal Fiber/Long Period Grating (PCF/LPG) sensor system to detect the concentration of gas and liquid or real-time monitor chemical reaction in extreme conditions, such as high temperature.;In addition, during the research on the WIM system, some related fundamental problems, such as the problem of mechanics of variable cross section beams, have also been extensively studied. |
