There is a growing demand for high precision positioning and navigation technologies for land vehicles, especially with the fast-emerging autonomous operation. Developing a robust vehicle navigation system that works well in all environments is still a challenging problem for automated level 2 driving. Global Navigation Satellite System (GNSS) receivers, Inertial Measurement Units (IMUs), and wheel odometers have been widely used to tackle this problem.
GNSS Precise Point Positioning (PPP) has become an attractive high precision alternative that can provide sub-meter level accuracy in favorable environments with no need for reference stations. Yet, such an accuracy degrades in challenging environments where the GNSS signals are attenuated or completely blocked. To reach robust and continuous navigation performance, PPP can be integrated with other navigation systems such as the Inertial Navigation System (INS).
This paper demonstrates the performance of Profound-IP3/DR, a low-cost PPP/INS integrated navigation system, recently developed by Profound Positioning Inc (PPI). The system is primarily targeting high precision vehicular navigation that requires continuous sub-meter level positioning accuracy along highways, even while driving along bridges and overpasses. Profound-IP3/DR also provides robust and competitive performance in suburban and urban environments. The integration with inertial sensors relies on Micro-Electro-Mechanical System (MEMS) grade IMU to maintain the system’s low-cost for wide adoption. Profound Positioning Inc. distributes the integrated navigation module to its customers as a software library or a turnkey system to be easily integrated for various automated driving applications.
Profound-IP3/DR was tested and validated through various road tests that cover good line-of-sight (LOS) GNSS environments, suburban, short GNSS outages, and complete GNSS outages. The test results indicate that the system can maintain sub-meter positioning accuracy in open-sky and suburban areas. For complete GNSS outage scenarios (e.g., an underground parking lot) and downtown scenarios with severe multipath, it shows robust long-term performance with meter-level accuracy. Based on the results, Profound-IP3/DR is expected to benefit low-cost, continuous, and precise land vehicular navigation and is ready for utilization in automated level 2 driving applications.
The test results indicate that
• In the open-sky environment, benefiting from the favorable GNSS LOS conditions, the Profound-IP3/DR solution mostly follows the IP3 solution with sub-meter level accuracy.
• During highway driving with several overhead bridges crossed, the Profound-IP3/DR solution smooths the spikes/jumps from the IP3 solutions due to the limited visible number of satellites and cycle slips when driving under the overpasses. Moreover, the proposed IP3/DR could bridge the transitory GNSS blockages by keeping sub-meter level accuracy and maintains continuous performance.
• For a typical downtown environment, Profound-IP3/DR outperforms the standalone IP3 solution and improves its degraded performance due to the challenges of severe multipath, poor satellite geometry, and signal blockage, etc. The system recognizes the GNSS environment and automatically weights the GNSS updates accurately. The smart combination of GNSS updates and inertial sensor measurements result in continuous meter-lever accuracy in such challenging environments.
• In a typical underground parking scenario, when GNSS is not available, and there is no PPP solution, Profound-IP3/DR could continuously provide a reliable navigation solution with meter-level accuracy.
Profound-IP3/DR has the advantage of providing a reliable and continuous positioning solution in all environments while utilizing low-end consumer-level inertial sensors and GNSS receivers. The high positioning accuracy opens the door for Profound-IP3/DR to be a key player in continuous and precise vehicular navigation applications such as asset tracking and safety assurance. The continuous sub-meter level positioning accuracy along highways makes Profound-IP3/DR ideal for automated level 2 driving applications.