Rotating LiDAR-Camera Synchronization Using Angle-Based Multi-Trigger Control
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Solution Overview
Problem
Existing methods for synchronizing rotating LiDAR and cameras in autonomous vehicle systems face challenges in achieving precise time synchronization, leading to data matching errors and underutilization of high-performance cameras, particularly in outdoor environments.
Innovation Solution
A method and device that utilize a synchronization control unit to transmit trigger signals to cameras based on the rotational angular velocity of the LiDAR, ensuring alignment and maximizing camera performance by adjusting trigger timing and signal transmission according to the cameras' operating frequencies and angles of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hardware switch is installed on a rotating LiDAR to physically provide a synchronization signal to the camera, then time synchronization precision is improved, but device reliability deteriorates due to durability problems of the physical switch
Solution Approach 1:
The patent replaces the mechanical hardware switch with an electronic solution. The LiDAR transmits rotation angle information electronically to the synchronization control unit, which then generates trigger signals for the cameras based on this data. This eliminates the need for physical switches while maintaining synchronization precision, thereby improving reliability.
Solution Approach 2:
The synchronization control unit acts as an intermediary between the LiDAR and cameras. It receives rotation angle information from the LiDAR, processes this data to determine appropriate trigger timing, and generates trigger signals for the cameras. This intermediary approach enables precise synchronization without requiring direct physical connection or hardware switches.
2Adaptability or versatility
If synchronization is accomplished on the basis of a camera having the lowest sampling rate, then synchronization compatibility is improved, but camera performance utilization deteriorates by wasting the performance of cameras with higher sampling rates
Solution Approach 1:
The patent implements dynamic trigger signal generation where the synchronization control unit adjusts trigger timing and frequency based on each camera's specific sampling rate and the LiDAR's rotation speed. Instead of forcing all cameras to the lowest sampling rate, the system dynamically adapts trigger signals to match each camera's capabilities, enabling all cameras to operate at their optimal performance levels.
Solution Approach 2:
The patent applies different trigger signal characteristics to different cameras based on their individual properties. Each camera receives trigger signals tailored to its specific sampling rate and performance characteristics, rather than using a uniform synchronization approach. This localized optimization allows each camera to fully utilize its performance while maintaining system-wide synchronization.
3Ease of operation
If time information from external devices is used for synchronization, then ease of operation is improved, but synchronization precision deteriorates making it difficult to secure precise synchronization between rotating LiDAR and camera
Solution Approach 1:
The patent implements a feedback mechanism where the LiDAR continuously provides rotation angle information to the synchronization control unit. This feedback enables the system to accurately track the LiDAR's real-time position and generate trigger signals that precisely correspond to the camera's field of view alignment, achieving high synchronization precision while maintaining ease of operation through automatic control.
Solution Approach 2:
The synchronization control unit pre-calculates and determines trigger timing based on the LiDAR's rotation angle information and the camera's field of view parameters. By performing this preliminary calculation of when the LiDAR will align with the camera's view direction, the system ensures precise synchronization without requiring complex real-time adjustments during operation.
Data Source
AI summary
A synchronization device according to an embodiment may include a Light Detection and Ranging (LiDAR), a plurality of cameras, and a synchronization control unit, and a method of synchronizing a rotating LiDAR and a camera according to an embodiment may include the steps of: outputting a sample according to a predetermined output period while rotating, by the LiDAR; acquiring the output sample, and deriving a trigger timing, which is an expected time for the LiDAR to rotate from a current position to a trigger target on the basis of the sample, by the synchronization control unit; transmitting a first trigger signal to the first camera and the second camera after a time of the trigger timing elapses, by the synchronization control unit; and additionally transmitting a second trigger signal only to the second camera after transmitting the first trigger signal, by the synchronization control unit.