Open-Source LiDAR Time Synchronization System by Mimicking GNSS-clock

TL;DR

This paper presents an open-source hardware-software system that emulates a GNSS-clock for highly accurate LiDAR sensor synchronization, achieving microsecond precision without needing a physical GNSS receiver.

Contribution

The authors introduce a flexible, open-source synchronization system using a microcontroller to emulate GNSS-clock signals, improving timing accuracy over existing software and internal clock methods.

Findings

Achieved 1 microsecond synchronization accuracy and precision.

Outperformed ROS software timestamping and LiDAR internal clocking schemes.

Demonstrated system adaptability for various sensors like cameras and IMUs.

Abstract

Data fusion algorithms that employ LiDAR measurements, such as Visual-LiDAR, LiDAR-Inertial, or Multiple LiDAR Odometry and simultaneous localization and mapping (SLAM) rely on precise timestamping schemes that grant synchronicity to data from LiDAR and other sensors. Poor synchronization performance, due to incorrect timestamping procedure, may negatively affect the algorithms' state estimation results. To provide highly accurate and precise synchronization between the sensors, we introduce an open-source hardware-software LiDAR to other sensors time synchronization system that exploits a dedicated hardware LiDAR time synchronization interface by providing emulated GNSS-clock to this interface, no physical GNSS-receiver is needed. The emulator is based on a general-purpose microcontroller and, due to concise hardware and software architecture, can be easily modified or extended for synchronization of sets of different sensors such as cameras, inertial measurement units (IMUs), wheel encoders, other LiDARs, etc. In the paper, we provide an example of such a system with synchronized LiDAR and IMU sensors. We conducted an evaluation of the sensors synchronization accuracy and precision, and state 1 microsecond performance. We compared our results with timestamping provided by ROS software and by a LiDAR inner clocking scheme to underline clear advantages over these two baseline methods.