Rangefinder Signal Processing for Overlapping Reflections
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Solution Overview
Problem
Conventional scanning rangefinders face challenges in accurately calculating distances due to noise light from semi-transparent objects and weather conditions, leading to incorrect distance measurements when obstacles or contaminants are present between the rangefinder and the target object.
Innovation Solution
A signal processing apparatus with a differential processing unit, waveform determining unit, and arithmetic unit that differentiates and separates reflection signals using first and second-order differential processing to determine the presence of overlapping reflected beams, allowing for accurate distance calculation based on the barycentric position of the first-order-differential reflection signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional noise filter is used to eliminate reflected beams from semi-transparent objects, then noise light from distant objects can be removed, but reflected beams from multiple overlapping objects cannot be distinguished and noise light cannot be eliminated
Solution Approach 1:
The patent segments the reflected beam signal into multiple components by detecting multiple peak values and their corresponding time points. The arithmetic unit then calculates distances for each segment separately, allowing differentiation between reflected beams from multiple objects that would otherwise overlap into a single indistinguishable signal.
Solution Approach 2:
The patent introduces a temporal dimension analysis by examining the time points corresponding to peak values in the reflected beam signal. By analyzing the time distribution and intervals between peaks, the system can distinguish between overlapping reflected beams from different objects, adding a time-based dimension to the signal processing beyond simple intensity filtering.
2Reliability
If all reflected beams are processed for distance calculation, then no reflected beam information is lost, but distance calculation becomes inaccurate due to noise light from weather conditions and obstacles
Solution Approach 1:
The patent performs preliminary analysis of the reflected beam signal by detecting peak values and their time points before final distance calculation. The waveform determining unit identifies characteristics of the reflected beam waveform in advance, allowing the arithmetic unit to selectively process only valid reflected beams and exclude those from noise sources such as weather conditions or intermediate obstacles.
Solution Approach 2:
The patent implements a feedback mechanism where the detected peak values and time points are used to validate and verify the authenticity of reflected beams. The system continuously monitors the reflected beam signal characteristics and adjusts processing based on detected patterns, providing feedback control to distinguish genuine target reflections from noise light caused by weather or obstacles.
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
Enables accurate distance measurement to the target object even with overlapping reflected beams from multiple objects, and corrects for errors caused by weather conditions like fog and rain, ensuring reliable operation in various environmental scenarios.
Implementation Method 1
a light emitting unit to output a pulse measurement beam
Implementation Method 2
a light receiving unit to detect a reflected beam reflected from a measured object present in the measurement target space and output a corresponding reflection signal
Implementation Method 3
a differential processing unit to differentiate the reflection signal output from the light receiving unit
Implementation Method 4
a scanning unit to periodically scan the measurement beam output from the light emitting unit in a deflected manner to a measurement target space through an optical window
Data Source
AI summary
A signal processing apparatus includes a differential processing unit to differentiate a reflection signal corresponding to a pulse measurement beam that is periodically scanned in a polarized manner; an arithmetic unit to obtain, with a rising time of a first-order-differential reflection signal as a reference, a barycentric position of the first order differential reflection signal as a detection time of a reflected beam, and to calculate a distance to a measured object based on a time difference between an output time of the measurement beam and the detection time of the reflected beam; and a waveform determining unit to determine whether the reflected beam includes a plurality of overlapping reflected beams from a plurality of measured objects, based on rising and falling characteristics of the first-order-differential reflection signal and based on a rising characteristic of a second-order-differential reflection signal obtained by the second order differential of the reflection signal.