Rotating Vehicle LiDAR Synchronization for Coherent Overlap Scans
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Solution Overview
Problem
Combining sensor data from multiple active sensors with partially overlapping fields of view (FOVs) can result in incoherent representations of the environment due to changes occurring between scans, such as object movements, making synchronization challenging.
Innovation Solution
Implementing a system with synchronized rotation of multiple LIDAR devices using a common timing signal and accounting for mounting positions to align yaw directions, ensuring simultaneous scanning of overlapping regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple LIDAR devices scan the environment independently, then each sensor can capture local environmental data, but the combined representation becomes incoherent due to changes occurring between scans
Solution Approach 1:
The system performs preliminary synchronization of multiple LIDAR devices before they begin scanning. A controller establishes a common timing signal and coordinates the scanning initiation of all LIDAR devices, ensuring they all start scanning at the same moment. This preliminary coordination prevents the coherence problem that would occur if devices scanned independently at different times.
Solution Approach 2:
The system uses feedback mechanisms where the controller receives status information from each LIDAR device and adjusts the timing signals accordingly. The controller monitors the scanning progress of each device and synchronizes their operation in real-time, ensuring that all devices are scanning simultaneously and their data remains coherent when combined.
2Area of stationary object
If LIDAR devices are mounted at different positions on the vehicle, then the system can cover a wider field of view, but parallax issues arise when combining data from overlapping regions
Solution Approach 1:
The controller performs preliminary calculations based on the known mounting positions of each LIDAR device. It pre-determines the appropriate timing offsets and synchronization parameters for each device based on their spatial arrangement. This preliminary preparation allows the system to compensate for parallax effects caused by different mounting positions while maintaining measurement precision.
Solution Approach 2:
The system adjusts various parameters including timing signals, scan rates, and data processing parameters based on the specific mounting positions of each LIDAR device. By changing these parameters dynamically according to the spatial configuration, the system maintains accurate environmental mapping even when devices are mounted at different locations.
3Reliability
If the system synchronizes multiple LIDAR devices, then coherent point cloud data can be produced, but the system complexity increases
Solution Approach 1:
The controller serves multiple functions: it manages the synchronization timing signals, coordinates the scanning operation of all LIDAR devices, processes the combined data, and compensates for parallax effects. By making the controller multi-functional, the system achieves reliable coherent data production without proportionally increasing overall system complexity.
Solution Approach 2:
The system merges the synchronization control functions into a single integrated controller that manages all LIDAR devices collectively. Rather than having separate synchronization mechanisms for each device, the controller consolidates all synchronization tasks into one unified system, reducing overall complexity while maintaining data coherence.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates the combination of data from multiple LIDARs into a coherent point cloud, mitigating parallax issues and enhancing environmental mapping accuracy.
Implementation Method 1
transmitting a laser pulse and detecting a returning pulse, if any, reflected from an object in the environment
Implementation Method 2
determining a distance to the object according to a time delay between the transmission of the pulse and the reception of the reflected pulse
Data Source
AI summary
One example system includes a first light detection and ranging (LIDAR) device that scans a first field-of-view defined by a first range of pointing directions associated with the first LIDAR device. The system also includes a second LIDAR device that scans a second FOV defined by a second range of pointing directions associated with the second LIDAR device. The second FOV at least partially overlaps the first FOV. The system also includes a first controller that adjusts a first pointing direction of the first LIDAR device. The system also includes a second controller that adjusts a second pointing direction of the second LIDAR device synchronously with the adjustment of the first pointing direction of the first LIDAR device.