The Research And Realization Of A Vehicle Weight-in-Motion Detecting System Based On Optical Fiber Sensor

With the high-speed development of the traffic, over-loading is coming from bad to worse. Over-loading not only destroys traffic infrastructures, but also causes traffic accidents frequently. So, Weight-in-motion (WIM) systems in the traffic system are becoming more and more important!In order to detect the traffics' weight in motion in real time, sensors to capture the signal of traffics should be designed first. At present, there are some kinds of sensors used in WIM system such as piezoelectricity sensor, capacitance sensor, bend plant sensor and so on. But in practice these sensors have many disadvantages because of the bad conditions in the investments. For example, their measuring results shift along with the changes of temperature and time. They have low electromagnetism anti-jamming quality and complicated equipment of instruments, etc.In recent years, DSP technology develops at very fast speed and optical fiber sensor technology is widely used in control and measurement domain. All of these provide technical convince for optical fiber sensor's application in WIM. In this paper, a new WIM system is proposed based on Mach-Zehnder optical fiber interferometer. Comparing with the traditional WIM systems mentioned above, this system has high measuring precision, good electromagnetism anti-jamming ability, faster response qualities. Further more, it is easy for working on the network conditions!The hardware of this WIM system is mainly made up of four parts: optic fiber sensor, analog circuit, digital circuit and the . The first part consists of lamp-house, Mach-Zehnder interferometer, PIN detector;the second part consists of the band-pass filter, amplifier circuit of analog signal. Digital circuit is based on DSP, produced by Texas Instrument Corporation, using Complex Programmable Logic Device (CPLD) produced by ALTERAL company to control the coding-schedule circuit of the whole system. The forth part is used for storing the data, making grids or fingers.Finally, this paper offers detailed discuss on every part of the system along withtraffic WIM theory, and achieves the realization of the system through software including data's collection and process and drawing the measurement curve. In further, this paper brings up amendatory scheme after analyzing the system's capacity and deficiency.