LiDAR Time Window Adjustment for ToF Accuracy
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Solution Overview
Problem
Light detection and ranging (LiDAR) systems face accuracy issues and increased measurement errors due to the need for a large number of histograms and errors in time of flight (ToF) measurements, especially in environments with abundant sunlight or at long distances, when using a fixed pulse width.
Innovation Solution
A LiDAR device that varies the time window based on measurement conditions such as distance to the object and illuminance, using a processor to adjust the pulse width and apply either a first or second time bin, thereby improving measurement accuracy and reducing the number of measurement cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed pulse width is used for ToF measurement, then the device complexity is reduced, but the measurement precision deteriorates in environments with abundant sunlight or at long distances
Solution Approach 1:
The patent applies dynamics by making the time window variable rather than fixed. The processor dynamically adjusts the time window width based on measurement conditions (distance to object and illuminance levels). When the object is far or sunlight is abundant, a narrower time window is used; when the object is close or sunlight is low, a wider time window is used. This dynamic adaptation resolves the contradiction by maintaining measurement precision across varying conditions without requiring multiple fixed-width systems.
Solution Approach 2:
The patent changes the parameter of time window width based on measurement conditions. The processor monitors distance and illuminance levels, then adjusts the time window parameter accordingly. This parameter change allows the system to maintain high measurement precision in both bright sunlight and long-distance conditions without increasing overall device complexity, as it uses a single adjustable parameter rather than multiple fixed systems.
2Measurement precision
If the number of histograms is greatly increased to secure accuracy, then the measurement precision is improved, but the productivity decreases
Solution Approach 1:
The patent uses a dynamic time window that adapts to measurement conditions, which improves measurement precision without requiring a large number of histograms. By concentrating measurement resources within an optimized time window, the system achieves high accuracy with fewer measurement cycles, thereby maintaining high operation speed. This resolves the contradiction by making the measurement process efficient rather than relying on brute-force multiple histograms.
3Measurement precision
If a narrow time window is used to reduce measurement error in long distance or bright sunlight conditions, then the measurement precision is improved, but the loss of information increases
Solution Approach 1:
The patent dynamically adjusts the time window width based on real-time measurement conditions. When the object is far or sunlight is abundant, a narrower time window is used to reduce measurement error. When the object is close or sunlight is low, a wider time window is used to capture sufficient reflected light and avoid information loss. This dynamic adaptation resolves the contradiction by optimizing the time window for each specific condition rather than using a fixed narrow window that would always risk information loss.
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 enhances the accuracy of ToF measurements and increases the operational speed of the LiDAR system by adapting the time window to environmental conditions, reducing measurement errors and the number of cycles required for histogram calculation.
Implementation Method 1
a light receiver that includes at least one light receiving region, wherein the light receiving region including a plurality of sub-light receiving regions, each of the plurality of sub-light receiving regions including a light detection element configured to receive the light reflected from an object
Implementation Method 2
a light transmitter configured to transmit light
Data Source
AI summary
A light detection and ranging (LiDAR) device and a method of measuring a distance are provided. The LiDAR device includes: a light transmitter configured to transmit light to an object; a light receiver that includes a plurality of sub-light receiving regions that are included in one light receiving region corresponding to one pixel, each of the plurality of sub-light receiving regions including a light detection element configured to receive the light reflected from the object; and a processor configured to determine a time of flight (ToF) of the light that is transmitted to and then reflected from the object by varying a time window according to a measurement condition.