Laser Scanner Dynamic Pulse Repetition Rate for Uniform Point Density
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Solution Overview
Problem
Conventional laser scanners face challenges in achieving uniform scanning point density due to distance-dependent scanning point distribution, leading to inefficiencies in generating reliable 3D point models, especially when scanning varying terrains, and are prone to 'blind ranges' due to pulse repetition rate limitations.
Innovation Solution
A laser scanner that adjusts its pulse repetition rate based on measured distance values from previous scan lines to ensure uniform scanning point distribution and avoid blind ranges by varying the pulse repetition rate across scan lines, using techniques such as sectioning the scan line into subsections and adapting the pulse repetition rate to match changing terrain and distance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant pulse repetition rate is used, then the device complexity is reduced, but the scanning point density becomes non-uniform across different distances
Solution Approach 1:
The pulse repetition rate is made dynamic rather than constant, adjusting automatically based on measured distance values from previous scan lines. This allows the system to maintain uniform scanning point density across varying distances without requiring complex manual control or preprocessing, as the adaptation happens in real-time during operation.
Solution Approach 2:
The system uses distance measurement values from previous scan lines as feedback to control the pulse repetition rate for current scan lines. This feedback mechanism enables automatic adjustment of scanning parameters to compensate for distance variations, achieving uniform point density while keeping the control system relatively simple.
2Productivity
If the pulse repetition rate is increased to improve scanning speed, then productivity increases, but blind ranges occur due to pulse overlap
Solution Approach 1:
The pulse repetition rate is dynamically adjusted based on distance measurements rather than using a fixed high rate. This allows the system to operate at high speeds when appropriate while avoiding pulse overlap conditions that cause blind ranges, thereby maintaining both productivity and measurement reliability.
Solution Approach 2:
The system changes the pulse repetition rate parameter adaptively based on measured distance values. By modifying this critical parameter in response to actual scanning conditions, the system optimizes scanning speed while preventing the occurrence of blind ranges that would compromise measurement reliability.
3Reliability
If the pulse repetition rate is reduced to avoid blind ranges, then measurement reliability improves, but scanning speed decreases
Solution Approach 1:
Rather than using a uniformly low pulse repetition rate, the system dynamically adjusts the rate based on actual distance measurements. This enables the system to achieve high scanning speeds when conditions permit while maintaining measurement reliability by reducing the rate only when necessary to avoid blind ranges.
Solution Approach 2:
The pulse repetition rate parameter is adaptively changed based on distance feedback, allowing the system to optimize between reliability and speed in real-time rather than being constrained by a fixed conservative setting.
4Measurement precision
If adjacent scan strips with overlapping regions are used to ensure sufficient scan point density, then measurement precision improves, but the quantity of measurements increases
Solution Approach 1:
The pulse repetition rate is locally adapted to distance conditions in different regions of the scanning field. This allows the system to achieve sufficient scan point density throughout the environment without requiring excessive overlapping scan strips, as the local adjustment of pulse rates compensates for distance-dependent density variations.
Solution Approach 2:
Rather than uniformly increasing scan line density through extensive overlapping strips, the system applies partial adjustment of the pulse repetition rate where needed. This achieves the necessary measurement precision with fewer total measurements by targeting adjustments to specific distance conditions rather than uniformly increasing overall scan density.
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
This approach enables the creation of 3D point models with uniform resolution and avoids blind ranges, reducing the complexity and cost of measurement tasks by dynamically adjusting the scanning parameters to match terrain changes and ensuring consistent scanning point density.
Implementation Method 1
determine a distance measurement value to the laser scanner for each sampling point by measuring the time of flight of the laser pulse reflected therefrom
Data Source
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Figure 3~5
Figure 6~7
AI summary
The invention relates to a laser scanner and a method for measuring an environment (4) in which laser pulses (Si,k) are emitted as a measuring beam (5) guided line by line at an angular velocity (ω) over the environment (4) with a variable pulse repetition rate (PRR) in order to generate successive scan lines (Li) of scan points (Pi,k) and to determine a distance measurement value (di,k) to the laser scanner (1) for each scan point (Pi,k) by measuring the time of flight of the laser pulse (Si,k) reflected thereon, wherein the pulse repetition rate (PRRn) in at least a subsection (An) of a current scan line (Li) depends on at least one distance measurement value (di,k) of at least one previous scan line (Li).