Utilize a Virtual Network Differential Global Navigation Satellite System to Achieve a Meter-Level Accuracy of 86.1 Percent for Lane Matching Applications.
Lane Matching Applications with a Virtual Network Differential Global Navigation Satellite System and a Single Point Positioning Approach Were Evaluated in California.
California, United States
Network Differential GNSS Corrections for Connected and Autonomous Vehicles
Summary Information
A Virtual Network Differential Global Navigation Satellite System (VN-DGNSS) and Single Point Positioning (SPP) approach were tested for how well they achieved the Society of Automotive Engineering (SAE)’s specifications. SAE specifications require 68 percent of horizontal positioning error to be less than 1.5 meters and 68 percent of vertical positioning error to be less than three meters. This study evaluated the implementation of a VN-DGNSS for connected and automated vehicles (CAV) with field tests occurring from March to November 2020. A VN-DGNSS is an enhancement to a primary GNSS system to improve the accuracy of position by using a network of reference stations that broadcast differential information to the user via a client-server architecture. When testing system and lane matching accuracy on a moving vehicle, three receivers were connected to one antenna. One receiver communicated with the VN-DGNSS server to receive real-time correction information. The second receiver operated in SPP mode, without external corrections. The third one was used to support real-time kinematic (RTK) fixed solution to achieve centimeter level accuracy. Researchers drove a vehicle 12 times on a testbed in a parking lot to evaluate positioning performance in the receivers.
Lessons learned in this project include:
- Employ a VN-DGNSS approach instead of an SPP approach for lane matching CAV applications. A VN-DGNSS approach achieved an accuracy of 99.2 percent when compared to the SAE standard of 1.5 meters (4.9 feet) from the center of the lane. When assessed for meter-level accuracy, this approach achieved an accuracy of 86.1 percent. The SPP approach instead achieved an accuracy of 88.6 percent (SAE standard) and 18.0 percent (meter-level standard).
- Employ a VN-DGNSS approach to accurately calculate the vertical position of a moving vehicle. Although both the N-DGNSS and SPP approaches surpassed the SAE specifications in horizontal positioning accuracy, the SPP approach did not achieve the SAE 3-meter vertical accuracy specification while the VN-DGNSS achieved a significantly higher accuracy than the SPP approach. The calculated error was expected to be within 3.0 meters (9.8 feet) of the vehicle’s actual position. VN-DGNSS achieved an accuracy of 99 .7 percent while SPP approach achieved an accuracy of 0 percent.
- Predict vehicle trajectories using a VN-DGNSS to accurately calculate RTK solutions. This approach achieved 90 percent accuracy when calculating solutions when the vehicle is within the following range: 1.4 meters (4.6 feet) from the center of the lane to 0.4 meters (1.3 feet) from the edge of the lane. Utilizing SPP-oriented solutions caused the accuracy to drop below 90 percent once the vehicle was more than 0.7 meters (2.3 feet) from the lane center or 1.1 meters (3.6 feet) from its edge. Accuracy for both systems was high when vehicles were less than 0.6 meters (2.0 feet) from the lane center.
