Adaptive Pulse Counting in Laser Scanners for Accuracy and Resolution
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Solution Overview
Problem
Opto-electronic measuring devices with scanning functionality face challenges in achieving high measurement accuracy and signal-to-noise ratio, particularly when measuring targets with low reflectivity or in environments with high background noise, leading to inadequate data capture and reduced spatial resolution.
Innovation Solution
The device employs a pulsed radiation source with an adaptive emission rate and a control unit that automatically adjusts the number of light pulses used for distance measurement based on real-time target object-related measured values, such as distance or signal strength, to optimize the signal-to-noise ratio and maintain spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of light pulses is increased to improve signal-to-noise ratio, then measurement accuracy is improved, but spatial resolution deteriorates due to reduced point density
Solution Approach 1:
The patent implements dynamic adjustment of the number of light pulses based on real-time signal quality assessment. The system evaluates signal-to-noise ratio and adapts the pulse count per scan point accordingly, transitioning from static to dynamic measurement parameters. This resolves the contradiction by allowing high pulse counts for poor signals (maintaining accuracy) while using low pulse counts for strong signals (maintaining spatial resolution).
Solution Approach 2:
The system changes the measurement parameter (number of light pulses) based on the measured signal characteristics. By monitoring signal strength and noise levels, the control unit adjusts the pulse count parameter in real-time, enabling the system to optimize between accuracy and spatial resolution depending on current measurement conditions.
2Measurement precision
If a fixed high number of light pulses is used for all scan points, then measurement accuracy is improved, but scanning time increases and productivity decreases
Solution Approach 1:
The system applies partial accumulation of light pulses only where necessary based on signal quality requirements. Instead of uniformly applying excessive pulse counts across all scan points, the control unit selectively increases pulse counts only for scan points with poor signal-to-noise ratios, maintaining high accuracy where needed while preserving scanning speed elsewhere.
Solution Approach 2:
The measurement process dynamically adapts the number of pulses based on real-time signal assessment, enabling the system to optimize between accuracy and speed for each individual scan point rather than using a fixed conservative setting for all points.
3Reliability
If the emission power is increased to improve signal strength, then detection capability is improved, but eye safety is compromised in close-range measurements
Solution Approach 1:
The system dynamically adjusts emission power based on measured distance to the target. For close-range measurements, power is reduced to ensure eye safety while compensating with increased pulse accumulation. For distant targets, higher power is permitted to maintain detection capability. This resolves the safety-performance contradiction through real-time adaptation.
Solution Approach 2:
The emission power parameter is changed based on distance measurements and signal quality requirements. The system transitions from fixed high power to adaptive power levels, combining power reduction with pulse count increase to maintain detection reliability while ensuring safety.
4Measurement precision
If signal accumulation over multiple pulses is performed, then signal-to-noise ratio is improved, but temporal resolution deteriorates due to longer measurement time per point
Solution Approach 1:
The system performs partial signal accumulation only when signal quality metrics indicate poor signal-to-noise ratio. For scan points with strong signals, no accumulation is performed, maintaining temporal resolution. For weak signals, accumulation is applied selectively, improving signal quality without unnecessarily extending measurement time across all points.
Solution Approach 2:
The degree of signal accumulation dynamically adapts based on real-time signal quality assessment, enabling the system to optimize between temporal resolution and signal-to-noise ratio for each measurement point rather than using a fixed accumulation strategy.
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 enhances measurement accuracy and spatial resolution by dynamically adjusting the number of pulses for each scan point, improving data quality and maintaining a consistent point density across varying distances, while also ensuring eye safety by reducing power in close-range measurements.
Implementation Method 1
a control unit with evaluation functionality for measuring a distance value to a respective scan point of the target object according to the time-of-flight principle, based on a number n≥1 of detected light pulses
Data Source
Figure 1~2a
Figure 2b~3
Figure 4a~4b
AI summary
The invention relates to an optoelectronic surveying device (90) with scanning functionality, in particular a laser scanner, profiler, laser tracker or total station, comprising a pulsed radiation source, in particular a pulsed laser source, for generating a measuring beam (91) from light pulses (2, 2', L, L1-L4, La-Lc) with a light pulse emission rate, an optoelectronic detector for detecting light pulses (2, 2', L, L1-L4, La-Lc) reflected from a target object (100, 100'), and a control and evaluation unit configured for measuring a distance value (Z, Z', M1-M3) to a respective scan point (P, P', P1', P2', P1-P7) of the target object (100, 100') according to the time-of-flight principle, based on a number n>=1 of light pulses (2, 2', L, L1-L4, La-Lc), wherein the control and evaluation unit is designed to automatically adjust the number (n) depending on a target object-related measurement value (Z, Z', M1-M3, Iges) determined in real time by the surveying instrument (90).