GNSS and Map-Matching Navigation Integrity Monitoring for Land Vehicles

In order to get an accurate location of a land vehicle in road networks in intelligent transportation systems (ITS), global navigation satellite systems (GNSS) and map-matching (MM) are essential components in the positioning system. Due to vulnerabilities of GNSS and fluctuating performance of map-matching in different scenarios, it is necessary to monitor the integrity of GNSS and map-matching. Especially in some mission-critical ITS applications such as route guidance, emergency management, electronic payment which are concerned with the safety of people and property. This research proposes a combined navigation integrity monitoring system to detect both positioning fault from GNSS and MM with the support of INS. To ensure that the receivers receive a sufficient navigation signal to carry out the integrity algorithm, this paper improves a multi-constellation GNSS integrity algorithm to detect GNSS faults. An integrity factor based on graph theory is designed to monitor the integrity of map-matching with the support of INS input. On the basis of previous reports, we improved the function of integrity factors through Euler number by considering the relationship between the quality and output of the navigation sensors. A multi-index comprehensive assessment method based on entropy weighting is proposed to measure the integrity of map-matching. The performance of the integrity method is evaluated using real map data in two scenarios. The simulation showed that the integrity method provided valid warnings 99.85% and 99.9% of the time for data collected in an urban area and a suburban area, respectively.