Time-of-Flight Distance Sensing Under Cluttered Reflections
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Solution Overview
Problem
Conventional distance measurement devices face inaccuracies in measuring distance due to clutter and multiple reflections, which affect the time of flight measurement, leading to reduced accuracy.
Innovation Solution
A distance measurement device that calculates object distance based on the time of flight of pulsed light, generates a histogram of received light intensity, determines the object's proximity based on the rising timing of the peak in the histogram, and acquires a feature value related to the number of reflections to reduce the impact of clutter and multiple reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time of flight measurement is used for distance calculation, then distance measurement can be performed, but measurement accuracy deteriorates due to clutter and multiple reflections
Solution Approach 1:
The patent segments the received light signal into multiple reflection components by generating histograms and identifying distinct peaks. Each peak corresponds to a different number of reflections (0 reflections, 1 reflection, 2 reflections, etc.), allowing the system to separate and analyze each component individually rather than treating the signal as a single aggregate measurement.
Solution Approach 2:
The patent extracts the primary reflection component (0 reflections) from the composite signal by identifying the first peak in the histogram. This extraction isolates the useful signal from harmful multiple reflections and clutter, enabling accurate distance measurement by considering only the direct light path between transmitter and object.
2Measurement precision
If histogram analysis with peak identification is implemented, then accuracy improves by reducing clutter impact, but device complexity increases
Solution Approach 1:
The system performs self-characterization by automatically identifying peaks and determining the number of reflections based on the temporal distribution of received light photons. The algorithm uses the inherent temporal structure of the reflected light signal to self-distinguish between multiple reflections without requiring external calibration or additional hardware components.
Solution Approach 2:
The patent employs periodic pulse emission and corresponding periodic histogram generation to capture the temporal structure of reflected light. By repeating the measurement process with periodic light pulses and accumulating photon arrival times in histogram bins, the system enhances signal-to-noise ratio and enables reliable peak identification through repeated sampling.
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 effectively reduces the measurement inaccuracies caused by clutter and multiple reflections, enhancing the accuracy of distance measurement, especially in short-distance ranges.
Implementation Method 1
calculate an object distance to the object using a time of flight of the pulsed light
Implementation Method 2
receives reflected light of the pulsed light reflected by an object
Data Source
AI summary
A distance measurement device includes a light emitter for transmitting pulsed light and a light receiver for detecting reflected light from an object, providing an output signal. The device has at least one of a circuit or a processor with memory storing executable computer program code. The circuit or processor calculates an object distance using the time of flight of the pulsed light. Additionally, a histogram representing received light intensity for each time of flight is generated from the output signal. The device determines whether the object is within a short-distance range based on the timing of a peak in the histogram, and calculates the object distance using both a feature value related to the number of light reflections and the timing of the peak's decline.