Distance Measurement via Histogram Shape Correction
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Solution Overview
Problem
Existing distance measuring technologies using Time-of-Flight systems fail to accurately measure distances to objects that cause subsurface scattering, as they do not account for the time attributed to light scattering within the object, leading to measurement errors.
Innovation Solution
A distance measuring apparatus and method that include a light-receiving unit, a histogram acquiring unit, and an operation unit, where the histogram acquiring unit detects the time of flight and produces a histogram of the reflected light, and the operation unit calculates the distance based on the histogram peak, correcting for the shape and environment light components to account for subsurface scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the time of flight is measured directly from light emission to reception, then the measurement process is simple, but the distance measurement accuracy deteriorates when the target causes subsurface scattering
Solution Approach 1:
The patent performs preliminary action by acquiring multiple histogram data sets at different time periods before final distance calculation. The operation unit stores multiple histogram data in a memory unit, each representing light reception frequencies at different time intervals. This preliminary data collection allows the system to identify and separate subsurface scattering components from surface reflection components, thereby improving measurement accuracy without significantly increasing device complexity.
Solution Approach 2:
The patent applies segmentation by dividing the histogram data into multiple time-period segments. Each histogram data corresponds to a specific time period, allowing the operation unit to analyze light reception frequencies separately for different time intervals. This segmentation enables the identification of subsurface scattering effects that occur at different times than surface reflections, resolving the accuracy issue while maintaining relatively simple processing.
2Measurement precision
If the histogram shape is used to correct the distance calculation, then the distance measurement accuracy improves for subsurface scattering objects, but the calculation complexity increases
Solution Approach 1:
The patent implements feedback by using the operation unit to analyze the shapes of multiple histogram data sets and use this analysis to correct the distance calculation. The system feeds back the histogram shape information into the distance calculation process, allowing automatic adjustment for subsurface scattering effects. This feedback mechanism improves accuracy while keeping the calculation complexity manageable through algorithmic processing rather than additional hardware.
Solution Approach 2:
The patent introduces histogram data as an intermediary between light reception and final distance calculation. The operation unit uses the histogram shape information as a mediator to indirectly account for subsurface scattering effects without requiring direct measurement of scattering time. This intermediary approach improves accuracy while avoiding the complexity of directly measuring and compensating for scattering delays.
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 objects that cause subsurface scattering by accounting for the time attributed to light scattering, improving measurement precision and reliability.
Implementation Method 1
receives reflected light from a distance measurement target, the reflected light being based on irradiation light from a light-emitting unit
Implementation Method 2
a device (a sensor) using a Time-of-Flight (ToF) system is known as a distance measuring apparatus that measures a distance to a distance measurement target (an object) by detecting the time of flight of light from emission of irradiation light from a light-emitting unit to the distance measurement target to reception of the irradiation light reflected from the distance measurement target
Implementation Method 3
some distance measurement targets cause so-called subsurface scattering, which is a phenomenon in which light incident on the surface of an object scatters inside the object and is then discharged to the outside
Data Source
AI summary
A distance measuring apparatus according to an embodiment of the present disclosure includes a light-receiving unit, a histogram acquiring unit, and an operation unit. The light-receiving unit receives reflected light from a distance measurement target. The reflected light is based on irradiation light from a light-emitting unit. The histogram acquiring unit acquires a histogram indicating the frequency of reception of the reflected light at the light-receiving unit. The operation unit calculates a distance to the distance measurement target on the basis of a time corresponding to a peak of the histogram acquired by the histogram acquiring unit. The operation unit corrects the distance calculated on the basis of the time corresponding to the peak of the histogram on the basis of the shape of the histogram acquired by the histogram acquiring unit.