Optical Distance Measurement Timing for Multi-Object Range Accuracy
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Solution Overview
Problem
Existing optical distance measurement systems using pulsed light face challenges in accurately distinguishing distances to multiple objects when the light emission interval is too short, leading to erroneous calculations due to overlapping time bins in the histogram, which results in the same distance value being assigned to objects at different distances.
Innovation Solution
The system adjusts the light emission interval and accumulation start period for pulsed light emissions, distributing the response signals across different time bins by varying the light emission intervals and using multiple histogram generation units, allowing for accurate distance calculations to objects within and beyond the maximum reachable distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light emission interval is shortened to increase measurement speed, then productivity is improved, but measurement precision deteriorates due to overlapping time bins causing erroneous distance calculations
Solution Approach 1:
The patent applies dynamics by making the light emission interval variable rather than fixed. The control unit dynamically adjusts the light emission interval based on the distance to the measurement target, using shorter intervals for nearby objects and longer intervals for distant objects. This dynamic adaptation allows the system to maintain high measurement speed while avoiding time bin overlap that causes precision errors.
Solution Approach 2:
The patent changes the temporal parameter (light emission interval) adaptively based on measurement conditions. By modifying the emission interval parameter according to target distance and histogram accumulation requirements, the system resolves the contradiction between fast measurement and accurate distance discrimination, preventing the same distance value from being assigned to objects at different distances.
2Productivity
If the light emission interval is too short, then the number of measurements per unit time increases, but reliability deteriorates due to overlapping response signals from different emission cycles
Solution Approach 1:
The system dynamically adjusts the light emission interval based on real-time measurement conditions and histogram accumulation progress. When objects are detected at different distances, the control unit extends the emission interval to prevent response signal overlap, ensuring reliable distance calculations while maintaining high measurement throughput through adaptive timing control.
Solution Approach 2:
The control unit uses feedback from the histogram generation process to adjust the light emission interval. By monitoring the accumulation of response signals and detecting potential overlaps, the system automatically modifies the emission timing to maintain measurement reliability, ensuring that each distance measurement corresponds to a unique object.
3Adaptability or versatility
If multiple objects at different distances are measured simultaneously, then adaptability is improved, but measurement precision deteriorates when response signals overlap in the same time bin
Solution Approach 1:
The patent implements dynamic adjustment of the light emission interval based on the distribution of objects at different distances. When multiple objects are detected, the control unit adapts the timing to spread response signals across different time bins, enabling simultaneous measurement of multiple objects while maintaining precise distance discrimination for each object.
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 approach reduces the likelihood of erroneous distance calculations by ensuring that response signals from objects at different distances are properly distinguished, expanding the measurable range and improving the signal-to-noise ratio.
Implementation Method 1
a light receiving element which receives the pulsed light reflected from a first object and is configured to output a response signal in accordance with received light intensity of the pulsed light
Implementation Method 2
generate a histogram by accumulating and recording the response signal output from the light receiving unit, corresponding to the number of times, in a time bin in accordance with time of flight of the pulsed light and calculate a distance to the first object on a basis of the histogram
Data Source
AI summary
An optical distance measurement apparatus includes a light source unit configured to emit pulsed light in units of the number of times determined in advance, a light receiving unit including a light receiving element which receives pulsed light reflected from a first object and configured to output a response signal in accordance with received light intensity of the pulsed light, and a control unit configured to generate a histogram by accumulating and recording the response signal output from the light receiving unit, corresponding to the number of times, in a time bin in accordance with time of flight of the pulsed light and calculate a distance to the object on the basis of the histogram. The control unit changes a light emission interval of the pulsed light by the light source unit within a unit of the number of times.