Displaying in-vehicle augmented reality content in a globally referenced coordinate system requires exact knowledge of the car’s global (world-frame) pose at a reasonably high framerate (90 Hz or more). LPVR-POS achieves this using a combination of specialized sensor fusion algorithms. Internally LPVR-POS is based on our FusionHub sensor fusion operating system that integrates a vehicle odometery data, RTK-GPS, and IMU data.

There are three different localization algorithms that LPVR-POS uses to deliver the best vehicle tracking performance to users.

GNSS-IMU fusion: This sensor fusion combines 3D inertial measurement data with direction and pitch data from a dual-antenna RTK-GPS system. As the GNSS system only delivers data at relatively low frame rates (10Hz) we use data from the accelerometer of the IMU to fill in the frames inbetween the GNSS position measurements. In this way we reach frequencies of up to 500Hz for the localization data. Additionally, the high precision gyroscope built into the LPVR-POS hardware allows us to track 3D orientation of the car referenced by the GNSS system’s orientation measurements.

Odometry-IMU fusion: The GNSS-IMU fusion has a significant weakness; if an RTK-GPS fix can’t be achieved, then the prediction calculations from integrating accelerometer data will drift off very quickly leading to hinaccurate localization output. This is where odometry / wheel velocity measurements come into play. At times when reference measurements from RTK-GNS aren’t available, direction measurements from the IMU gyroscope and the vehicle speed can work to bridge the gap.

Full vehicle fusion: This method combines the strengths of the GNSS-IMU and odometry-IMU algorithms. The odometry-IMU fusion creates a virtual GNSS signal that’s forwarded to the GNSS-IMU fusion to calculate high-framerate, 3D vehicle position and orientation output. This result has the best of both worlds, it’s robust and continuous over RTK-GPS outages, while still maintaining calculation of 3D poses at frequencies suitable for augmented and mixed reality scenarios.

Applications

• VR/AR-based in-car guidance systems
• ADAS test systems
• In-vehicle entertainment systems

Documentation

LPVR-POS manual

Specifications

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