LIDAR Time-Windowing for Precise Long-Range Distance Sensing
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Solution Overview
Problem
Existing LIDAR devices face challenges in achieving high precision distance measurements over a broad range of distances, particularly beyond 100 meters, while also requiring a large number of frames to maintain spatial accuracy, which increases response time and reduces the number of measurable points.
Innovation Solution
The method involves determining a pulse width for pulsed laser light that is smaller than the maximum time of flight associated with the maximum distance, and dividing the detection time period into consecutive detection time windows, allowing for distance measurements with improved temporal precision and reduced number of frames required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pulse width is reduced to improve temporal precision, then measurement precision is improved, but the detection time period becomes insufficient for broad distance ranges
Solution Approach 1:
The detection time period is divided into multiple consecutive detection time windows, each window corresponding to a specific distance range. This segmentation allows the system to use short pulse widths for high temporal precision while covering broad distance ranges by distributing detection across multiple windows.
Solution Approach 2:
The system dynamically adjusts which detection time windows are active based on the expected distance range. By making the detection scheme adaptive and dynamic, the system can optimize for both precision and range coverage depending on operational conditions.
2Measurement precision
If multiple frames are taken to maintain spatial accuracy, then measurement precision is improved, but response time increases
Solution Approach 1:
The patent replaces the mechanical/frame-based accumulation approach with a temporal windowing approach. Instead of requiring multiple frames to accumulate sufficient signal, the system uses multiple detection time windows within a single frame to achieve the same measurement precision, thereby reducing response time.
3Loss of time
If the pulse width is reduced to enable single-frame measurements, then response time is improved, but the number of measurable points decreases
Solution Approach 1:
The patent adds the dimension of temporal windowing to the measurement process. By dividing the detection time period into multiple consecutive windows and assigning each window to measure specific points, the system can maintain a high number of measurable points while using short pulse widths for fast response.
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 enables high precision distance measurements over a broad range of distances with a reduced number of frames, improving the overall response time of the LIDAR device and allowing for single-frame measurements with acceptable accuracy.
Implementation Method 1
the time interval between the emission of the laser light and the detection of reflected laser light is proportional with twice the distance to an object of the scene
Implementation Method 2
detecting reflected laser light in a detector generally located near the laser source that emitted the laser light
Data Source
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AI summary
The present disclosure relates to a method and device for determining distances to a scene. The method comprises steps of determining a laser light pulse width PW that is smaller a maximum time of flight TOFmax corresponding to a maximum distance Dmax by using a pulse width reduction factor N such that PW = (TOFmax – TDL) /N wherein TDL is a predefined delay window, determining a pulse frequency FP such that FP ≤ 1/((N+1) x PW + TDL), illuminating the scene with an illuminating pattern comprising a plurality of spatially separated pulsed laser beams having the determined pulse width and frequency, performing the detection as function of time during a detection time period TD divided in M = α x (N+1) consecutive detection time windows, with α ≥ 1, such that TD = M x (PW/α), identifying in what detection time windows reflected laser light is detected and calculating a distance to the scene based on this identification.