# Portable Optical Fiber Bragg Grating Sensor for Monitoring Traffic Density
## 4 Conclusions  
This paper examines the design, production and experimental verification of the functionality of a portable measuring sensor created from a combination of silicone rubber and a fiber Bragg grating placed inside a carbon tube. The selected encasing method did not affect the functionality of the Bragg gratings. Due to the silicone rubber curing, the Bragg wavelength was shifted 608 pm higher. The rubber material alone caused an increase in temperature sensitivity to 13.3 pm/\({}^{\circ}\)C.  
The sensor was created and designed to measure selected parameters in traffic. Experimental measurements were conducted in real traffic. Initial measurements were conducted in a quiet suburban part of Ostrava over 7 h. A total of 140 cars passed during this experiment and resulted in a successful detection rate of 99.286% (139 cars). A second, comprehensive experiment was conducted at the main entrance to the VSB-TUO campus over 12 h (from 06:00 to 18:00). During this set of measurements, 1502 vehicles were successfully detected from a total of 1518 (detection success rate of 98.946%). The sensor's high sensitivity and success rate in detecting cars is a good prerequisite for expanding research and development into this portable sensor for monitoring automotive traffic. Follow-up research will be done to improve the design in order to achieve a more stable sensitivity in the sensor over its entire active length. This should increase the sensor's success rate in detecting vehicles. Another objective is to extend the detection capabilities of the sensor, as driving direction and vehicle speed are important parameters in monitoring traffic density. The team of authors are also striving to design the sensor for year-round use. Any follow-up research will therefore also focus on verifying functionality during winter climatic conditions with a continuous layer of snow. [PERSON]. ([PERSON]), and [PERSON] ([PERSON]) proposed the systems idea and edited the manuscript. [PERSON]. ([PERSON]), [PERSON] ([PERSON]), [PERSON], [PERSON], [PERSON], and [PERSON] developed, tested and validated data. [PERSON]. ([PERSON]), [PERSON] ([PERSON]), [PERSON] and [PERSON] wrote the manuscript. [PERSON]. ([PERSON]), [PERSON] ([PERSON]), and [PERSON] critically evaluated the quality of the research data and experimental methods used to generate/acquire them as well as the soundness/validity of the scientific and engineering techniques, wrote the manuscript, and performed its final edits. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Local Road** & **Campus VSB-TUO** \\ \hline N & 140 & 1518 \\ TP & 139 & 1502 \\ FP & 5 & 40 \\ FN & 1 & 16 \\ SE (\%) & 99.286 & 98.946 \\ ACC (\%) & 95.862 & 96.405 \\ PPV (\%) & 96.528 & 97.406 \\ F1 (\%) & 97.887 & 98.170 \\ FNR (\%) & 0.714 & 1.054 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Classification analysis of detected car passes. **Funding:** The paper was funded with support of conceptual development of science, research and innovation in 2018, assigned to VSB-Technical University of Ostrava, The Ministry of Education, Youth and Sports in the Czech Republic. This article was supported by the Ministry of Education of the Czech Republic (Project No. SP2019/79). This article was also supported by the European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project, project number CZ.02.1.01/0.0/0.0/16_019/0000867 within the Operational Programme Research, Development and Education. This work was supported by the European Regional Development Fund in Research Platform focused on Industry 4.0 and Robotics in Ostrava project, CZ.02.1.01/0.0/0.0/17_049/0008425 within the Operational Programme Research, Development and Education. This research was partially supported by the Ministry of Education, Youth and Sports of the Czech Republic through the grant project No. CZ.1.07/2.3.00/20.0217 within the frame of the operation program Education for Competitiveness financed by the European Structural Funds and from the state budget of the Czech Republic.