Performance Analysis of Single-Frequency Single-Epoch GNSS/INS Integrated Navigation in Typical Urban Environments

With the rapid development of multi-constellation GNSS, GNSS positioning has been widely applied in several fields. In urban environment, GNSS signals are vulnerable to external interference, and the centimeter-level accuracy of GNSS positioning cannot be obtained to extent the required for automatic driving. To improve the accuracy of position estimation in urban environments, the integration of GNSS and inertial navigation system was examined in this study, and the single-frequency, single-epoch positioning performance of single GNSS and GNSS/INS integrated navigation was analyzed through dynamic GNSS and IMU data collected from a vehicle. The experimental results showed that the efficiency ratio of GNSS data was 99.80% even when the GPS, GLONASS and BDS were used in an urban environment; moreover, the utilization rate of the GNSS data was only 97.37% because of low-accuracy observations caused by the complex urban environment. In the urban environment, the positioning accuracy of a single GNSS was reduced, and the integration of GNSS and inertial navigation system could improve the performance of single GNSS positioning. The results indicated that the performance of loosely coupled of GNSS/INS is affected if the positioning solution has severe bias because of incorrectly fixed ambiguity. Compared with other methods, the tightly coupled of GNSS/INS can obtain the optimal position solution in typical urban environments.