Fiber Optic Sensor For Measuring Load Of Vehicle On Highway
This paper reveals from the investigation on a special optical fiber as a load sensor for application in Weigh-in-Motion (WIM) systems to measure wheel loads of vehicles traveling at normal speed on highways. The fiber used has a unique design with two concentric light guiding regions of different effective optical path lengths, which has the potential to enable direct measurement of magnitudes as well as locations of forces acting at multiple points along a single fiber. The optical characteristic of the fiber for intended sensing purpose was first assessed by a simple fiber bending experiment and by correlating the bend radii with the output light signal intensities. The device with the optical fiber was tested under a universal loading machine and an actual vehicle wheel in the laboratory. The test results showed a good relationship between the magnitude of the applied load and the output optical signal changes. The results also showed a good correlation between the time delay between the inner and outer core light pulses and the distance of the applied load as measured from the output end of the fiber. This paper reports on the WIM installation and calibration efforts and investigates the preliminary results of data analysis of two types of piezoelectric WIM sensors in the period after sensors’ calibration. An auto-calibration algorithm for the most effective piezoelectric WIM sensors will be provided in the future to supply calibration factors for Ontario’s climate and for high speed, high volume roads, while collection of WIM data will provide an opportunity for investigating the load spectra impacts on the pavement designs. Fiber optics sensor technology offers different parameter measurements such as strain, pressure, temperature, current and many more things. For that different type of sensors are used and these sensors converts these parameters to optical parameters like light intensity or phase or polarization of light. These converted parameters are transmitted using an optical link over a long distance.
Keywords- Weight-in-Motion, Intrinsic & Extrinsic optical sensor ,point-to-point protocol, FTDM Fiber.