Multi-Scan LiDAR Fan Overlap for Uniform 3D Sampling
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Solution Overview
Problem
Existing laser scanning devices face limitations in achieving high spatial resolution and uniform distribution of scan points due to multiple time-around (MTA) zones and blind ranges, which restrict the pulse repetition rate and result in uneven sampling of the environment.
Innovation Solution
A laser scanning device with multiple scanning units emitting overlapping scan fans, controlled by a control unit to pivot scan compartments relative to each other based on the pulse repetition rate and angular velocity profile, ensuring geometric separation of laser pulses and uniform sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pulse repetition rate is increased to improve scanning speed and resolution, then productivity is improved, but the multiple time around problem occurs causing measurement errors
Solution Approach 1:
The patent divides the single scanning function into multiple scanning units (first scanning unit, second scanning unit, etc.), each operating at high pulse repetition rates. By segmenting the scanning task across multiple units with different timing, the system achieves high overall productivity while each unit maintains measurement precision within its operational window.
Solution Approach 2:
The patent employs periodic scanning cycles where multiple scanning units operate in alternating or coordinated sequences. Each scanning unit operates periodically with its own pulse train, allowing the system to maintain high average productivity while each individual unit adheres to timing constraints that prevent multiple time around problems.
2Quantity of substance
If the pulse repetition rate is increased to improve sampling density, then the number of scanning points increases, but blind ranges occur at MTA zone edges due to receiver saturation
Solution Approach 1:
The patent segments the reception function into multiple receiving units, each associated with a specific scanning unit. This segmentation allows each receiver to handle only the pulses from its corresponding scanner, distributing the reception load and preventing saturation while maintaining high scanning point density across the entire field of view.
Solution Approach 2:
The control device acts as an intermediary that coordinates the operation of multiple scanning units and their associated receiving units. It manages the timing and synchronization to ensure that reflections from different scanning units do not simultaneously saturate the receiving electronics, thereby maintaining reception reliability.
3Productivity
If multiple scanning units are used to increase scanning points, then productivity is improved, but the complexity of positioning and coordinating the scan fans increases
Solution Approach 1:
The patent merges the control functions of multiple scanning units into a single centralized control device. This control device coordinates all scanning units and receiving units, managing their timing and positioning to eliminate coincidence of scanning points. By combining control functions, the system achieves high productivity while keeping the coordination mechanism manageable.
4Duration of action of moving object
If the pulse repetition rate is increased to reduce measurement time, then duration of action is reduced, but the maximum measurable distance range decreases due to MTA zone limitations
Solution Approach 1:
The patent extends the measurement capability from a single distance range (limited by MTA zone of one scanner) to multiple overlapping distance ranges by introducing multiple scanning units. Each scanner covers a specific angular sector with its own MTA zone, and the combination of multiple scanners effectively extends the measurable distance range across the entire field of view while maintaining high pulse repetition rates.
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 device achieves a significantly higher resolution and uniform distribution of sampling points across the environment by allowing multiple scan fields to overlap and rescan areas, enhancing the quality and speed of 3D point cloud generation.
Implementation Method 1
a laser transmitter (12) for emitting a pulse train (4) of laser pulses (5)
Implementation Method 2
a deflection device (14) with rotating mirror surfaces (17) for fanning out the laser pulses (5) in scan directions (R)
Implementation Method 3
the target distances are derived from transit time measurements of the target reflections
Data Source
Figure 1~2
Figure 3a~3d
Figure 4~5
AI summary
Device (1) for measuring an environment (2), comprising a first and at least one further scan unit (6k), each for emitting a pulse train (4k) of laser pulses (5k,n) over successive deflection periods (APk,p) with a pulse repetition rate (PRR), wherein the laser pulses (5k,n) falling within each deflection period (APk,p) form a scan fan (8k) per deflection period (APk,p), which they traverse with a predefinable angular velocity profile (ω), and for receiving the associated laser pulses (5k,n) reflected from the environment (2), wherein all scan fans (8k) overlap in the direction of one of the scan axes (7k), and a control device (29) connected to the at least one further scan unit (6k), which is configured toto pivot the scan compartments (8k) of each additional scan unit (6k) relative to the scan compartments (8k-1) of an adjacent scan unit (6k-1) by a swivel angle (λk,k-1) dependent on the pulse repetition rate (PRR) and the angular velocity profile (ω) such that their scanning points (Pk,n) do not coincide.