Multi-Scan LiDAR Offset Control for Uniform 3D Point Clouds
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Solution Overview
Problem
Existing laser scanning devices face limitations in achieving high spatial resolution and uniform distribution of sample points in 3D point clouds due to constraints on deflection period, pulse repetition rate, and blind ranges, leading to uneven sampling and reduced quality of the 3D point cloud.
Innovation Solution
The device employs multiple scanning units that emit and receive laser beams simultaneously, with controlled spatial and temporal offsets to ensure scan lines do not coincide, allowing for increased sampling points and uniform distribution across the environment, thereby enhancing resolution and quality of the 3D point cloud.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the deflection period is shortened to increase scanning speed, then the distance between consecutive scan lines decreases, but the resolution within a scan line reduces due to fewer sample points
Solution Approach 1:
The patent divides the scanning function into multiple independent scanning units, each capable of emitting laser beams and receiving reflections. This segmentation allows parallel processing of scanning tasks, effectively increasing the number of sample points without requiring shorter deflection periods, thus maintaining both scanning speed and resolution.
Solution Approach 2:
Multiple scanning units are combined to work simultaneously, with their scan lines arranged in parallel arrays. The control device coordinates these units to offset their scan line sets, creating a unified scanning system that achieves higher resolution through combined sampling points from multiple units.
2Measurement precision
If the pulse repetition rate is increased to improve sampling density, then the number of sampling points increases, but MTA zones expand causing blind ranges at edges
Solution Approach 1:
The patent segments the measurement task across multiple scanning units, each operating with its own pulse repetition rate and MTA zone. By distributing the sampling points across multiple units with offset scan lines, the system achieves high sampling density without expanding individual MTA zones, thus minimizing blind ranges.
Solution Approach 2:
The patent introduces a spatial dimension by arranging scan lines from multiple scanning units in parallel arrays with specific offsets. This dimensional arrangement allows the system to overcome the one-dimensional limitation of single-unit MTA zones, enabling continuous coverage across extended distance ranges.
3Measurement precision
If multiple scanning units are added to increase sampling points, then spatial resolution improves, but scan line coincidence occurs reducing measurement quality
Solution Approach 1:
The control device dynamically offsets the scan line sets of different scanning units based on their relative positions and scanning speeds. This dynamic coordination ensures that scan lines from multiple units are spatially separated to avoid coincidence, while maintaining uniform sampling distribution across the measurement area.
Solution Approach 2:
The control device receives information about the scanning units' positions and speeds, using this feedback to calculate and adjust the offsets between scan line sets. This feedback mechanism ensures optimal spacing between scan lines from different units, preventing coincidence and ensuring uniform sampling density.
4Productivity
If the relative speed is increased to improve productivity, then the number of scan lines per unit time increases, but the distance between scan lines increases reducing resolution
Solution Approach 1:
The patent merges multiple scanning units to work simultaneously at high speeds. Each unit maintains its own scan line generation capability, and by combining the output of multiple units with offset scan lines, the system achieves high productivity through parallel scanning while maintaining fine resolution through the distributed sampling points.
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
The solution enables rapid and high-quality generation of 3D point clouds with improved spatial resolution and uniform sampling, overcoming limitations of single-unit scanning devices by doubling the sampling points and ensuring consistent coverage.
Implementation Method 1
measuring the time of flight of laser beams reflected therefrom
Implementation Method 2
measuring the time of flight of laser beams reflected therefrom in a coordinate system
Data Source
Figure 1~2
Figure 3a~3c
Figure 4~5
AI summary
Device for measuring an environment (2) moving relative to the device (1) by measuring the time of flight of laser beams (4) reflected therefrom, comprising a first and at least one further scan unit (5k), each for emitting a laser beam (4k) over a sequence (Fk) of deflection periods (APk,p) with a respective deflection period duration (TAP), which passes through a scan fan (6k) in each deflection period (APk,p) and scans the environment (2) along a scan line (7k), wherein the scan lines (7k,p) of each scan unit (5k) form a set of scan lines (10k), and for receiving the associated laser beam (4k) reflected from the environment (2), and a control device (22) connected to the at least one further scan unit (5k), which is configured toto shift the scan line set (10k) of each further scan unit (5k) relative to the scan line set (10k) of an adjacent scan unit (5k-1) in the direction of movement (R) by a position offset (ΔSk,k-1) dependent on the relative velocity (v) and the deflection period (TAP) such that their sampling points (Pk,n) coincide.