Dual Threshold Binarization for LiDAR Distance Measurement Precision
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Solution Overview
Problem
Conventional stereo cameras face challenges in achieving good distance resolution at far distant regions due to fluctuations in disparity calculation results, and struggle to detect weak reflection signals amidst noise, particularly in the context of autonomous driving where improved range finding performance is demanded.
Innovation Solution
A light signal detection device incorporating a light receiving optical system, first and second binarization units, and a time measurement unit to enhance the detection of reflection signals by setting threshold values and measuring time differences, integrated with a stereo image processing unit to improve range finding accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single threshold value is used for binarizing the reflection signal, then the detection process is simple, but weak reflection signals from distant objects cannot be distinguished from noise
Solution Approach 1:
The single threshold value is segmented into multiple threshold values (first threshold value and second threshold value) to handle different signal strength scenarios. The first threshold value is used for strong reflection signals while the second threshold value is used for weak reflection signals from distant objects, enabling the system to distinguish weak signals from noise without excessive complexity
Solution Approach 2:
The system applies partial binarization by selectively using different threshold values based on signal characteristics. Instead of applying a complex multi-threshold analysis to all signals, it uses a second threshold value specifically for weak signals that need enhanced detection, avoiding unnecessary processing complexity for already detectable signals
2Measurement precision
If the second threshold value is set too low to detect weak signals, then distant objects can be detected, but noise signals are also detected as valid signals
Solution Approach 1:
The system uses feedback through histogram analysis of binarized signal distributions to dynamically determine appropriate threshold values. By analyzing the distribution of signal intensities and identifying peaks in the histogram, the system can set the second threshold value to distinguish weak valid signals from noise while maintaining high detection accuracy for distant objects
Solution Approach 2:
The system performs preliminary binarization using a first threshold value before applying the second threshold value. This preliminary action filters out obvious noise and strong signals, allowing the second threshold value to focus specifically on detecting weak reflection signals from distant objects without being overwhelmed by noise
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 enhances the accuracy of range finding by effectively distinguishing weak reflection signals from noise, even at distant objects, thereby improving the overall range finding performance and distance measurement precision.
Implementation Method 1
a light receiving optical system configured to receive a reflection signal reflected from an object when irradiation light emitted from an irradiation unit hits the object and reflects from the object
Implementation Method 2
a time measurement unit configured to measure a time difference between a time of emitting the irradiation light from the irradiation unit and a time of receiving a reflection signal
Data Source
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AI summary
A light signal detection device (44) includes a light receiving optical system (30) configured to receive a reflection signal reflected from an object when irradiation light emitted from an irradiation unit (10) hits the object and reflects from the object; a first binarization unit (44c1) configured to binarize the reflection signal received by the light receiving optical system (30) using a first threshold value, based on a determination of whether the reflection signal is equal to or greater than the first threshold value; a second binarization unit (44c2) configured to binarize the reflection signal received by the light receiving optical system (30) using a second threshold value set with a given value similar to a noise signal value, based on a determination of whether the reflection signal is equal to or greater than the second threshold value; and a time measurement unit (45) configured to measure a time difference between a time of emitting the irradiation light from the irradiation unit (10) and a time of receiving a reflection signal equal to or greater than the first threshold value or the second threshold value.