Safety Monitoring System of CAVs Considering the Trade-Off between Sampling Interval and Data Reliability

• Published in: Sensors (Basel, Switzerland) Vol. 22; no. 10; p. 3611
• Main Authors: Tak, Sehyun, Choi, Seongjin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 10.05.2022; MDPI
• Subjects: Automation; Communication; Communication networks; Communications systems; Compression ratio; connected and automated vehicles; cooperative intelligent transportation system; Data acquisition; Data collection; Data entry; Data processing; data reliability; Data transmission; Deceleration; Efficiency; Field tests; Health aspects; Indicators; Intelligent transportation systems; Local transit; Middleware; Monitoring; Monitoring systems; Position indicators; Public health; safety monitoring system; Sampling; Sensors; Tradeoffs; Traffic control; Traffic flow; Urban transportation; Vehicles; South Korea; data reliability; connected and automated vehicles; safety monitoring system; cooperative intelligent transportation system
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s22103611

The safety of urban transportation systems is considered a public health issue worldwide, and many researchers have contributed to improving it. Connected automated vehicles (CAVs) and cooperative intelligent transportation systems (C-ITSs) are considered solutions to ensure the safety of urban transportation systems using various sensors and communication devices. However, realizing a data flow framework, including data collection, data transmission, and data processing, in South Korea is challenging, as CAVs produce a massive amount of data every minute, which cannot be transmitted via existing communication networks. Thus, raw data must be sampled and transmitted to the server for further processing. The data acquired must be highly accurate to ensure the safety of the different agents in C-ITS. On the other hand, raw data must be reduced through sampling to ensure transmission using existing communication systems. Thus, in this study, C-ITS architecture and data flow are designed, including messages and protocols for the safety monitoring system of CAVs, and the optimal sampling interval determined for data transmission while considering the trade-off between communication efficiency and accuracy of the safety performance indicators. Three safety performance indicators were introduced: severe deceleration, lateral position variance, and inverse time to collision. A field test was conducted to collect data from various sensors installed in the CAV, determining the optimal sampling interval. In addition, the Kolmogorov-Smirnov test was conducted to ensure statistical consistency between the sampled and raw datasets. The effects of the sampling interval on message delay, data accuracy, and communication efficiency in terms of the data compression ratio were analyzed. Consequently, a sampling interval of 0.2 s is recommended for optimizing the system's overall efficiency.