LiDAR Sensor Reflectivity Measurement Using APD and SPAD
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Solution Overview
Problem
Existing LiDAR sensors for vehicles face challenges in accurately measuring reflectivity at both long and short distances without using high-end devices like high-speed analog-to-digital converters (ADC), which are costly and limit the implementation of low-cost sensors.
Innovation Solution
A LiDAR sensor system that includes a transmitter, receiver, and signal processor capable of detecting objects at both long and short distances by gradually reducing light intensity, using avalanche photodiodes (APD) or single photon avalanche diodes (SPAD) to determine reflectivity based on activation maintenance time or frequency, respectively, without relying on high-end ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-end devices such as high-speed ADC are used in LiDAR sensor, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent replaces expensive high-speed ADC devices with cheaper APD or SPAD devices that have different operational characteristics. By using these lower-cost photodetectors and measuring activation maintenance time or activation frequency, the system achieves reflectivity measurement without requiring high-end ADC hardware, thus reducing device cost while maintaining measurement capability.
Solution Approach 2:
The patent changes the measurement parameter from direct high-speed signal conversion (requiring high-speed ADC) to activation maintenance time or activation frequency measurement. This parameter transformation enables the use of slower, cheaper photodetectors like APD and SPAD while still achieving accurate reflectivity measurements through the temporal characteristics of photon detection.
2Length of stationary object
If high-output laser is used to measure long distance in LiDAR sensor, then detection range is improved, but activation time increases and reflectivity measurement capability deteriorates
Solution Approach 1:
The patent employs periodic or pulsed laser transmission instead of continuous high-output laser. By transmitting light in discrete pulses and measuring the activation maintenance time or activation frequency of photons returned from the object, the system achieves long-distance detection capability while maintaining short activation times and preserving reflectivity measurement accuracy through the temporal analysis of returned light signals.
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 measurement of reflectivity at various distances using cost-effective components, allowing for the implementation of low-cost LiDAR sensors for vehicle applications, including autonomous vehicles and advanced driver assistance systems.
Implementation Method 1
an avalanche photodiode (APD) or the like based on a method of measuring an activation maintenance time of a cell included in a sensor
Implementation Method 2
a single photon avalanche diode (SPAD) or a silicon photomultiplier (SiPM) based on a method of measuring an activation frequency
Implementation Method 3
a transmitter configured to generate light and transmit the light to an object
Implementation Method 4
a receiver configured to receive light reflected from the object
Data Source
AI summary
Provided are a light wave detection and ranging (LiDAR) sensor, an operating method thereof, and a vehicle including the LiDAR sensor. The LiDAR sensor is configured to detect surroundings of a vehicle, and includes a transmitter configured to generate light and transmit the light to an object, a receiver configured to receive light reflected from the object, and a signal processor configured to detect the object by processing a signal of the light received by the receiver, wherein the object is detectable both at a long distance and a short distance, and when the object is detected at the short distance, the transmitter outputs light while gradually reducing an intensity of the light, compared to when the object is detected at the long distance, and the signal processor determines reflectivity for a cell included in a sensor on the basis of an activation maintenance time or an activation frequency in the cell according to the signal while the intensity of the received signal of the light is reduced gradually.