LiDAR Range Estimation Using Intensity Ratio Analysis
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Solution Overview
Problem
Range estimation in LiDAR systems is impaired by the use of low sampling rate ADCs, which fail to accurately determine the arrival time of laser pulses due to insufficient waveform reconstruction, leading to inaccurate distance measurements.
Innovation Solution
The system employs a processor to calculate an intensity ratio between data points from multiple specifically timed laser pulses, determining the arrival time and estimating the range using a low sampling rate ADC, thereby improving accuracy and reducing system costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-speed ADC is used to sample the returned laser pulse at a high frequency, then the waveform reconstruction accuracy is improved, but the system cost and noise increase substantially
Solution Approach 1:
The patent segments the waveform reconstruction process by using multiple specifically timed laser pulses instead of relying on a single high-frequency sampled waveform. Each pulse provides discrete timing information that, when combined, enables accurate arrival time determination without requiring high-speed ADC sampling for each individual pulse.
Solution Approach 2:
The system performs preliminary timing measurements by emitting multiple laser pulses at known time intervals and recording their return times. This preliminary data collection enables the processor to calculate arrival times and determine range without requiring the ADC to capture every detail of the waveform at high speed, thus reducing the ADC sampling rate requirement.
2Device complexity
If a low sampling rate ADC is used, then the system cost is reduced, but the waveform reconstruction accuracy deteriorates
Solution Approach 1:
The patent employs periodic action by emitting multiple laser pulses at regular time intervals and using the periodic sampling of these pulses to reconstruct timing information. The ADC samples the return signals at these periodic intervals, and the processor uses the known time differences between pulses to accurately determine arrival times, compensating for the low sampling rate through the periodic structure of the measurements.
Solution Approach 2:
The patent introduces the processed digital signal as an intermediary that bridges the gap between low-speed ADC sampling and accurate arrival time determination. The processor analyzes the digital signal containing multiple pulse return times and calculates the arrival time by comparing the timing information across different pulses, thereby mediating between the limited sampling capability and the required measurement precision.
3Measurement precision
If multiple specifically timed laser pulses are used to determine arrival time, then range estimation accuracy is improved, but the computational processing requirements increase
Solution Approach 1:
The patent applies self-service by having the system use its own emitted pulse timing information to aid in the measurement process. The known time intervals between emitted pulses and the recorded return times are combined by the processor to self-determine accurate arrival times, eliminating the need for complex external timing systems or high-speed sampling, thus reducing overall computational burden despite using multiple pulses.
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 method enhances the accuracy of range estimation in LiDAR systems while using a low-cost ADC, reducing computational power and enabling applications in autonomous driving and high-definition mapping.
Implementation Method 1
The LiDAR receiver typically includes a detector to convert the returned laser pulse into an electrical signal
Implementation Method 2
a LiDAR system measures the distance to a target by illuminating the target with pulsed laser light beams and measuring the reflected pulses
Implementation Method 3
The laser pulse is backscattered and returned by the object
Implementation Method 4
The distance to the object (also referred to as the 'range') can be estimated based on a time difference between an emitting time of the laser pulse and an arrival time of the returned laser pulse
Data Source
AI summary
Embodiments of the disclosure provide an optical sensing system, a range estimation system for the optical sensing system, and a method for the optical sensing system. The exemplary optical sensing system includes a transmitter configured to emit a plurality of laser pulses towards an object. The optical sensing system further includes a range estimation system configured to estimate a range between the object and the optical sensing system. The range estimation system includes an analog to digital converter (ADC) configured to convert a plurality of laser pulses returned from an object to a digital signal. The ADC has a predetermined sampling period. The exemplary system further includes a processor. The processor is configured to calculate an intensity ratio between two data points selected from the digital signal. The processor is further configured to determine an arrival time of the first returned laser pulse based on the intensity ratio and a time difference between respective sample times of the two data points. The processor is also configured to estimate a range between the object and the optical sensing system based on the arrival time of the first returned laser pulse.