Nový monitor dopravního provozu na bázi optovláknového interferometru

Abstract

The dissertation deals with the development of a new type of traffic sensor based on a fiber optic interferometer, which does not need to be embedded in the road or attached to the rail. The dissertation summarizes the properties of transport monitoring technologies including the fiber-optic currently in use. The individual interferometer configurations and their suitability for the intended application are evaluated. Methods of phase demodulation and the design of a new type of sensor are also discussed. Novel traffic sensor was then exposed to the external phenomena, especially day and night temperature cycles. Due to the significant fluctuations in the interference visibility resulting from the exposure, the design of the sensor was optimized and several solutions were proposed for the Mach-Zehnder interferometer using the polarization-maintaining fibers or by the utilization of unpolarized radiation source. An unpolarized radiation source greatly increases interference visibility stability, but it still needs to be compensated. One of the outputs is also the predictive visibility model for the sensor, which can predict visibility changes based on time, further reducing sensor’s measurement error. In the last part of the work, the sensor was experimentally verified as a rail vehicle detector and a road traffic monitor, and it proved to be fully functional in both areas.