Weighing Of Moving Vehicles Using Fiber Optic Polarimetric Sensor

Vehicular weight measurement while the vehicle is in motion has a significant application in traffic monitoring and weight regulation. While a conventional weighing scale requires vehicles to be sidetracked to a weighing scale, the current on-line system can provide a means of instantaneous measurement while the vehicle is moving. This would improve the throughput of heavily laden vehicles. The basis of this system is a Fiber Optic Polarimetric Sensor (FOPS) based on the principle of change in polarization of the light transmitting through the polarization maintaining (PM) fiber when subjected to external perturbation. The system is capable of static, transient and dynamic measurements. Circularly polarized laser light is coupled into the PM fiber, which is then subjected to the weight of the moving vehicle driven over it. The output from the photodetector is then displayed and analyzed using the software developed using LabView. The relationship between the weight of the moving vehicle and the wheel signature generated as vehicle passes over the pad is represented using a mathematical model. An accuracy of 86% in weight measurement of moving vehicles is achieved through this proposed system.