Research On Fiber Optical Weigh-in-motion Technology

Speeding and overloading of vehicles are two illegal acts that seriously threaten traffic safety.The problem of vehicle overspeed has been solved by speed measuring radar and video technology.However,due to the lack of effective means,overloading is still a high incidence of illegal acts.In addition,high-speed accurate toll collection and intelligent transportation real-time monitoring have practical needs for accurate acquisition of vehicle load.Although the existing static weight measurement methods such as weighbridge have high measurement accuracy and good accuracy,but the measurement time is long and the traffic efficiency is low,which seriously affects the speed of vehicle flow,so the weight in motion(WIM)emerges as the times require.In this paper,in view of the shortcomings of the current dynamic weighing sensor,the micro bending optical fiber pressure sensor array technology is used to carry out the research of vehicle dynamic weighing technology.First of all,the response process of the vehicle passing through the weigh in motion system is studied theoretically.The simulation of the step response and impulse response of the second-order system provides a theoretical reference for the sensor design.The micro bend optical fiber with sandwich structure of deformer-fiber and elastomer-deformer is designed and developed.The signal of micro bend optical fiber pressure sensor is realized by pulse self-reference demodulation technology.The influence of light source intensity fluctuation,system noise and power on repeatability on measurement is analyzed.Finally,the dynamic weighing principle experiment based on the fiber optic pressure sensor array is carried out.The static and dynamic characteristics of the pressure sensor are measured.And the vehicle speed measurement is studied.The static sensitivity of the pressure sensor is-0.0087/N.The research results show that the highway dynamic weight measurement system based on optical fiber pressure sensor has the advantages of simple structure,easy demodulation,low cost and high measurement accuracy,and has potential application value.