SPAD Distance Measurement Using Statistical Peak Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional distance measuring devices using single photon avalanche diodes (SPADs) face challenges in accurately determining peak times in histograms due to the lack of theoretical validity in threshold settings, leading to potential erroneous measurements.
Innovation Solution
A distance measuring device that includes a histogram acquisition unit, a detection unit performing statistical processing on the histogram to detect active light components, and a measurement unit that measures distance based on the distribution of these components, with optional noise removal and adaptive weighted addition processing to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a threshold-based method is used to determine peak time in the histogram, then the distance measurement can be performed, but the peak detection may be erroneous due to lack of theoretical validity in threshold settings
Solution Approach 1:
The patent changes the parameter used for peak detection from a fixed threshold value to a statistically-derived value based on the standard deviation of the histogram data. Specifically, the peak time is detected when the histogram value exceeds the average value plus a predetermined multiple of the standard deviation, providing theoretical validity and improving both accuracy and reliability
Solution Approach 2:
The patent implements feedback by using the statistical properties (average and standard deviation) of the histogram data itself to determine the peak detection threshold, rather than using an externally-set fixed threshold. This adaptive approach allows the system to adjust to varying signal conditions and improves measurement reliability
2Measurement precision
If light is emitted and received multiple times to obtain superior data, then the measurement accuracy improves, but the measurement time increases
Solution Approach 1:
The patent performs a predetermined number of light emission and reception operations (excessive action) to accumulate sufficient histogram data for accurate statistical analysis. By performing more measurements than the absolute minimum, the system ensures high measurement accuracy while keeping the total number of operations predetermined and controlled
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 and reliable distance measurement by appropriately identifying peak times and reducing noise, thereby improving the precision of distance calculations to a target object.
Implementation Method 1
a time-of-flight (ToF) method using a SPAD is known. In this ToF method, distance measurement is performed by emitting pulsed light from a light emitting unit and receiving the light reflected from a target object with a SPAD sensor
Implementation Method 2
distance measurement is performed by emitting pulsed light from a light emitting unit and receiving the light reflected from a target object
Data Source
AI summary
An appropriate peak detection is performed on the basis of a histogram indicating a frequency of reception of reflected light to measure a distance to a target object. A histogram acquisition unit acquires a histogram indicating the frequency of reception of reflected light including active light components that are active light emitted from a light emitting unit and reflected by the target object and ambient light components that are ambient light reflected by the target object. A detection unit detects a distribution of the active light components by performing predetermined statistical processing on the histogram. A measurement unit measures the distance to the target object as distance information on the basis of the distribution of the active light components.