Reflection Rate Correction for ToF Ranging
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Solution Overview
Problem
Existing Time of Flight (ToF) ranging methods face accuracy issues due to the deviation of the histogram peak from the theoretical distance, caused by varying reflectivities of target objects and excessive intensity of reflected light pulses.
Innovation Solution
A reflection rate correction ToF ranging method that involves obtaining statistical results of photon flight time, determining the start time of detecting the light pulse, and calculating the distance based on this start time and the emission time of the light pulse, thereby reducing the impact of different reflectivities and light intensities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the peak position of the histogram is used to determine photon flight time, then the ranging process is simple, but the accuracy of distance measurement deteriorates due to histogram peak deviation caused by varying target reflectivities
Solution Approach 1:
The patent extracts the start time of detecting the light pulse from the histogram peak position. Instead of using the peak position which is affected by reflectivity, the invention identifies the start time as a separate parameter from photon flight time calculation, thereby eliminating the deviation caused by varying target reflectivities while maintaining simple ranging operation
Solution Approach 2:
The patent performs preliminary identification of the start time of detecting the light pulse before calculating photon flight time. By determining the start time first from statistical results and then subtracting it from the histogram peak position, the invention corrects the measurement accuracy issue while keeping the overall process straightforward
2Measurement precision
If multiple light pulses are emitted to generate large number of photon flight events, then statistical analysis becomes more reliable, but the time required for accurate ranging increases
Solution Approach 1:
The patent extracts and uses only the necessary portion of statistical data - specifically the start time of detecting the light pulse - rather than requiring complete statistical convergence of multiple pulses. This allows accurate ranging with fewer pulses by focusing on the critical start time parameter rather than waiting for full histogram stabilization
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 method improves the accuracy of determining the distance to a target object by isolating the start time of detecting the light pulse from the intensity of the reflected light, thus minimizing measurement errors caused by varying reflectivities and light intensities.
Implementation Method 1
A single-photon avalanche diode pixel, configured to respond to detected photons
Implementation Method 2
By using a timer to record the start time of the light pulse emission from the light pulse emitter and the end time when the photon detector detects the photons reflected by the target object, the photon flight time is determined
Data Source
AI summary
A reflection rate correction Time of Flight (ToF) ranging method including: obtaining statistical results of photon flight time of a light pulse reflected by a target object; where the statistical results include detection times of photons and photon quantities corresponding to the detection times; determining a start time of detecting the light pulse based on the statistical results; determining a distance to the target object based on the start time of detecting the light pulse and a start time of emitting the light pulse.