Lidar Intensity Calibration for Uniform Multi-Channel Reflectivity
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Solution Overview
Problem
Lidar intensity values in autonomous vehicles are non-uniform due to signal noise and other factors, leading to inaccuracies in localization, perception, and motion planning.
Innovation Solution
A method for off-line calibration of Lidar intensity values using a data collection stage to gather point data at various angles and power levels, with a linear model to compute calibration multipliers and bias values for each channel, allowing for the derivation of calibrated intensity values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Lidar intensity values are used directly from multiple channels, then the system provides comprehensive environmental data, but the intensity values are non-uniform due to signal noise and alignment variations
Solution Approach 1:
The patent applies preliminary action by performing calibration computations before actual Lidar operation. Calibration multipliers and bias values are pre-computed for each channel based on manufacturer specifications and stored in memory. During operation, these pre-computed values are automatically applied to correct intensity measurements, eliminating the need for real-time calibration complexity while ensuring uniform intensity values across all channels.
2Measurement precision
If calibration multipliers and bias values are computed for each channel, then intensity uniformity across channels is improved, but the data collection and processing complexity increases
Solution Approach 1:
The patent applies universality by creating a standardized calibration framework that works across all channels simultaneously. A single linear model (Equation 1) is used for all channels, with calibration multipliers and bias values computed based on universal manufacturer specifications. This universal approach simplifies the calibration process while achieving uniform intensity values across all channels, as the same methodology applies to every channel without requiring channel-specific complex procedures.
3Measurement precision
If offline calibration is performed with multiple targets at various distances and angles, then calibration accuracy is improved, but the calibration time and resource requirements increase
Solution Approach 1:
The patent applies preliminary action by performing the comprehensive calibration process during manufacturing or initial setup, before the Lidar system enters normal operation. The calibration data collection involving multiple targets at various distances and angles is completed in advance, and the resulting calibration multipliers and bias values are stored for reuse. This eliminates the need for repeated calibration during operation, reducing calibration time loss while maintaining high calibration accuracy.
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 calibration method aligns Lidar intensity returns with reflectivity, providing more accurate information for improved vehicle localization, perception, and motion planning.
Implementation Method 1
each channel emits a laser signal into the environment that is reflected off of the surrounding environment back to the detector
Implementation Method 2
circuitry to measure the time of flight—i.e., the elapsed time from emitting the laser signal to detecting the return signal
Data Source
AI summary
Aspects of the present disclosure involve a vehicle computer system comprising a computer-readable storage medium storing a set of instructions, and a method for light detection and ranging (Lidar) intensity calibration. The method includes collecting a data set comprising a plurality of raw intensity values output by a channel of a Lidar unit at a particular power level from among multiple power levels at which the channel is capable of operating. The method further includes using a linear model to compute a calibration multiplier and a bias value for the particular power level of the channel. During operation of the vehicle, calibrated intensity values are determined by applying the linear model to subsequent raw intensity values output by the channel at the particular power using the determined calibration multiplier and bias value.