Real-time speed, classification, and weigh-in-motion using a single, spatially distributed fiber-optic sensor

In this report a real time system that uses a microbend fiber optic sensor to estimate speed, classification, and weight of a moving vehicle is studied theoretically and experimentally. In the first chapter a historical review of the multiple facts and techniques used for vehicle classification and weigh in motion (WIM) is presented. This is followed, in chapters two and three, with the principles of spatially distributed sensors and sensor characteristics; as well as, other factors that affect the system's performance including tire inflation, load versus tire's contact length, environmental pavement changes, etc. Non real time classification and WIM data were analyzed with three different WIM techniques and two different classification techniques. The best method for classification was the fixed threshold. The method that gave the best WIM results was the area under the curve. Non real time hardware and software used to collect and analyze data are presented in the fourth chapter along with the non real time data analysis. The hardware that was designed to implement the real time analysis is addressed in the fifth chapter along with the basic algorithms of the embedded firmware of the microcontroller. The sixth chapter demonstrates the process of data collection cycle. The software receives the processed data from the hardware through a serial port, formats it, then displays and saves to files for further analysis. The real time data using the prototype hardware and software are presented in the seventh chapter along with statistical analysis of the system performance for separate classification and WIM. Finally, the conclusion and recommendations for further work are covered in the eighth chapter.; Appendix A presents the FHWA scheme F classification table, along with a brief description of the vehicle classes and definitions. Appendix B presents the vehicles used for testing the prototype classification and WIM system. Appendix C presents a number of footprints of a tire varying its air pressure. Appendix D presents the same tire's footprints while varying the load in the vehicle. Finally in Appendix E the derivation of the Area WIM method is presented.