Rotary LiDAR Camera Synchronization via Trigger Timing
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Solution Overview
Problem
Existing methods for synchronizing rotary LiDAR and cameras in autonomous vehicle systems face challenges in achieving precise time synchronization, leading to data mismatch errors, which are critical in diverse outdoor environments.
Innovation Solution
A LiDAR-camera synchronization device that estimates a trigger timing for the LiDAR to rotate to a target position and outputs a trigger signal to the camera, ensuring synchronized data capture by calculating the average angular velocity and deriving a trigger timing based on the rotation angle differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time information from external devices is used for synchronization, then synchronization is achieved, but precise matching between rotary LiDAR and camera cannot be secured
Solution Approach 1:
The patent replaces the mechanical/physical synchronization approach (hardware switches) with a computational/software-based solution. The synchronization control unit calculates trigger timing by deriving average angular velocity from LiDAR rotation samples and computing the time required for the LiDAR to rotate from its current position to the trigger target position, thereby substituting mechanical synchronization with algorithmic timing calculation to achieve precise data matching.
Solution Approach 2:
The system performs preliminary calculations of average angular velocity and trigger timing in advance. The synchronization control unit continuously monitors LiDAR rotation samples and pre-calculates the timing information needed for future trigger events, allowing the camera to be triggered at the precise moment when the LiDAR reaches the target position, thus ensuring accurate spatial-temporal alignment between the two sensors.
2Reliability
If hardware switches are installed in rotary LiDAR to provide synchronization signals, then time synchronization problem is solved, but durability problems occur
Solution Approach 1:
The patent eliminates mechanical hardware switches by implementing a software-based synchronization control unit that calculates trigger timing based on LiDAR rotation samples. This computational approach replaces the mechanical contact system with an electronic/software system that has no moving parts, thereby solving the durability issue while maintaining synchronization reliability.
Solution Approach 2:
The synchronization control unit acts as an intermediary between the LiDAR and camera systems. Instead of using physical switches to directly trigger the camera, the control unit receives rotation samples from the LiDAR, calculates the appropriate trigger timing, and then generates the trigger signal for the camera, thereby mediating the synchronization through computational logic rather than mechanical contact.
3Measurement precision
If rotation angle differences are calculated to derive trigger timing, then precise synchronization is achieved, but calculation complexity increases
Solution Approach 1:
The system implements feedback by continuously monitoring LiDAR rotation samples and using the measured rotation data to calculate average angular velocity. This feedback loop allows the synchronization control unit to dynamically adjust trigger timing based on actual rotation performance, achieving high precision while keeping the algorithm relatively simple through iterative measurement and calculation.
Solution Approach 2:
The synchronization control unit performs preliminary calculations of average angular velocity based on collected rotation samples before generating trigger signals. By pre-calculating the timing parameters and storing them for future reference, the system reduces real-time computational complexity while maintaining high trigger timing accuracy through advance preparation of synchronization parameters.
Data Source
AI summary
Proposed are a method of synchronizing a rotary LiDAR and a camera, and a device thereof. The synchronization device may include a LiDAR, a camera, and a synchronization control unit. The method of synchronizing a LiDAR and a camera may comprise the steps of: outputting a sample at every predetermined output cycle while rotating, by the LiDAR; deriving a trigger timing that is a time estimated for the LiDAR to rotate from a current position to a trigger target on the basis of the sample, by the synchronization control unit; and outputting a trigger signal to the camera after a time indicated by the trigger timing elapses, by the synchronization control unit. The sample may include a rotation angle indicating the current position of the LiDAR, and the trigger target may indicate a virtual direction in which the center of the angle of view of the LiDAR matches that of the camera.