Precise positioning drives lane-level accuracy in automotive industry

GNSS positioning algorithms combined with automotive-grade GNSS chipsets, inertial measurements and GNSS corrections services from a ground network of reference stations can deliver instant lane-level accuracy.

By Tasha Wong Ken and Sara Masterson, Hexagon Positioning Intelligence

Autonomous technology is reshaping the future of the automotive industry and Hexagon’s Positioning Intelligence Division (Hexagon PI) is developing cutting-edge positioning solutions to support the growth of this rapidly changing industry.

Hexagon PI is working with GNSS chipset manufacturers like STMicroelectronics to deliver automotive-grade, multi-frequency GNSS chipsets that combine our positioning algorithms with automotive-grade GNSS hardware to deliver solutions for connected cars, advanced driver-assistance systems (ADAS) and autonomous driving applications.

In June, Hexagon PI introduced TerraStar X GNSS correction technology, which enables lane-level vehicle positioning in under a minute, using automotive-grade chipsets and the Hexagon PI positioning engine. Built on the company’s latest precise point positioning (PPP) algorithms, TerraStar X leverages existing Hexagon capabilities in ground network infrastructure, correction data generation, and data packaging for delivery.

FIGURE 1. TerraStar X correction data generation and delivery to the vehicle. (Image: Hexagon PI)

By combining Hexagon PI’s software positioning engine with GNSS measurements from automotive-grade chipsets and inertial measurement unit (IMU) data, TerraStar X GNSS correction services can deliver instant lane-level accuracy positioning.

TerraStar X combines existing TerraStar global clock and orbit data with regional ionospheric correction data from Hexagon’s vast network of SmartNet reference stations. This forms the technology foundation for future correction services on connected cars, ADAS and autonomous driving markets, including integrity and authentication for safety-critical applications.

FIGURE 2. The Hexagon PI positioning engine achieves seamless position accuracy by taking GNSS measurements from the Teseo V GNSS receiver, combining it with their positioning algorithms, GNSS+INS coupling, and TerraStar X correction technology. (Image: Hexagon PI)

TABLE 1. Cumulative distribution of horizontal errors from testing on German roads. (Table: T. W. Ken and S. Masterson)

HxGN SmartNet consists of a large operational reference station network, consisting of more than 4,500 stations with continuous quality monitoring and support. Correction data generation takes place at Hexagon processing centers where service reliability, redundancy and 99.999% guaranteed service uptime ensure corrections are available for users 24/7/365.

While TerraStar X utilizes the stations already available, the algorithms are flexible and will accommodate the rollout of new service areas with increased station separation, enabling continental-scale coverage.

TerraStar X technology will deliver correction data to vehicles and end users through hybrid delivery channels, including both cellular network and satellite. Combining TerraStar X technology with multiple delivery channels ensures that vehicles, UAVs, industrial vehicles, trains, and more will operate safely, securely, reliably, and efficiently.

TerraStar X testbeds are being utilized for several advanced automotive development programs in North America and Europe, TerraStar X commercial services will be available in 2019. Interested customers can request access to any of the testbeds through Hexagon PI.

Positioning Engine. Hexagon PI’s positioning engine architecture enables a flexible integration with different GNSS receiver chipsets, augmentation sensors and processor environments, providing automotive manufacturers with additional flexibility when it comes to sourcing components and subsystems of ADAS and autonomous driving solutions.

The positioning engine is being developed to Automotive Safety Integrity Level (ASIL)-B standards and will include a proprietary GNSS integrity solution to ensure safe positioning within defined protection limits tailored to the customer’s application requirements.

Recent test results

Hexagon PI conducted demonstrations in Michigan and Germany using an automotive platform that combined automotive-grade GNSS hardware with TerraStar X technology and the software positioning engine to demonstrate instant lane-level accuracy with correction data delivered over the cellular network to test vehicles.

The results are from the most recent demonstration performed in urban conditions in Germany. The route consisted of a mix of controlled-access highway and light urban roads in the city. In this case, the positioning engine using TerraStar X and GNSS+INS coupling deliver 1-meter accuracy through 95% of the dataset.

FIGURE 3. Cumulative distribution of horizontal errors from tests on German roads. (Figure: T. W. Ken and S. Masterson)

Throughout the data collection, position accuracy improves by almost 70% when TerraStar X and the positioning engine is used. In some areas, it was found that the position solution can improve up to 95% with the Hexagon PI positioning solution over the standalone Teseo V, an automotive-grade GNSS receiver from STMicroelectronics.

FIGURE 4. Horizontal position errors from testing on German roads. (Figure: T. W. Ken and S. Masterson)

Looking ahead in automotive

Hexagon PI continues to demonstrate the benefits of precise positioning on automotive-grade chipsets using augmentation sensors, our positioning engine, and TerraStar X technology in a variety of environments worldwide. Our goal is to develop a solution for mass-production that provides accurate and functionally safe positioning to enable the advancement of autonomy in the automotive industry.