RTK and PPK GNSS Positioning Accuracy Assessment for UAVs Using a PPS-Synchronized Robotic Total Station

Area of Science:

• Geomatics Engineering
• Robotics
• Geodetic Surveying

Background:

• Accurate drone positioning is critical for photogrammetry and environmental monitoring.
• Real-Time Kinematic (RTK) and Post-Processed Kinematic (PPK) are key differential GNSS techniques for high-accuracy drone navigation.
• Existing performance assessments often lack direct comparison with independent ground-truth data under dynamic flight conditions.

Purpose of the Study:

• To directly compare the positioning performance of RTK and PPK for drone applications.
• To evaluate accuracy using an independent robotic Total Station (TS) as a ground-truth reference.
• To analyze the behavior of RTK and PPK during GNSS signal degradation in dynamic flight scenarios.

Main Methods:

• Developed a Versatile External Synchronization and Telemetry Architecture (VESTA) platform integrating GNSS, IMU, and synchronized data logging.
• Implemented a synchronization method using the GNSS Pulse-Per-Second (PPS) signal and TS prism motion.
• Conducted flight experiments comparing RTK and PPK positioning against TS measurements.

Main Results:

• RTK and PPK demonstrated comparable accuracy under optimal GNSS conditions.
• PPK solutions experienced longer float/degraded states and larger transient errors than real-time RTK (u-blox) after GNSS degradation with the RTKLIB-EX configuration.
• The choice between RTK and PPK depends on dynamic performance and reconvergence, not just nominal accuracy.

Conclusions:

• Direct comparison using a TS reveals dynamic performance differences between RTK and PPK.
• PPK's reconvergence behavior after GNSS disruptions is a critical factor for drone applications.
• RTK may offer more robust real-time positioning during dynamic flight with intermittent GNSS signal loss.