Nonlinear Chirp Linearization for Accurate FMCW LiDAR Range and Velocity
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Solution Overview
Problem
Existing LiDAR sensors face challenges in simultaneously determining the range and velocity of objects due to the use of non-linear chirp signals, which are costly and inaccurate, and are susceptible to interference from light sources like sunlight.
Innovation Solution
A LiDAR sensor system that includes a fiber optic ending, laser assembly, and processors to divert a portion of the non-linear chirp signal for profiling and best fit curve determination, allowing for linearization of the signal to accurately calculate range and velocity using a frequency offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-linear laser sources are used to produce chirp signals, then cost is reduced, but measurement precision and reliability deteriorate due to non-linear frequency variation
Solution Approach 1:
A linearization module is introduced as an intermediary component between the non-linear laser source and the FMCW LiDAR sensor system. This module processes the non-linear chirp signal to generate a linearized version, enabling the use of inexpensive non-linear laser sources while maintaining the measurement precision required for accurate range and velocity determination.
Solution Approach 2:
The patent transforms the frequency-time parameters of the chirp signal by applying linearization processing. The non-linear frequency variation characteristic of commercial laser sources is converted into a linear frequency variation pattern, allowing standard FMCW processing algorithms to function correctly and achieve accurate measurements.
2Device complexity
If time of flight LiDAR sensors are used, then device complexity is reduced, but functionality deteriorates as they cannot simultaneously determine range and velocity
Solution Approach 1:
The FMCW LiDAR sensor system is designed to perform multiple functions simultaneously: it can determine both range and velocity of objects using the same hardware platform. The linearized chirp signal enables the system to extract both distance information (through frequency offset) and velocity information (through Doppler effect), providing multi-functional capability that surpasses traditional time-of-flight LiDAR.
3Measurement precision
If FMCW LiDAR sensors are used with linear chirp signals, then measurement precision is improved, but device complexity and cost increase due to requiring specialized linear laser sources
Solution Approach 1:
The linearization module serves as an intermediary that bridges the gap between simple non-linear laser sources and the requirements for linear chirp signals in FMCW LiDAR. This intermediary component enables the system to achieve high measurement precision without requiring complex and expensive linear laser sources, thus reducing overall device complexity.
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 determination of range and velocity of objects by linearizing non-linear chirp signals, improving precision and reducing interference susceptibility.
Implementation Method 1
In time of flight principles, time differences between emitted laser pulses and returned laser pulses can be measured or determined. Ranges (e.g., distances) of objects in an environment can be determined based on these time differences.
Implementation Method 2
a velocity of the object can be simultaneously determined by the FMCW LiDAR sensors using doppler effect principles
Implementation Method 3
The fiber optic ending can comprise a fiber optic cable terminated by a reflector. The laser assembly can emit a chirp signal to detect an object in an environment. A portion of the chirp signal can be diverted to the fiber optic ending.
Implementation Method 4
The fiber optic ending can comprise a fiber optic cable terminated by a reflector
Data Source
AI summary
A light detection and ranging (LiDAR) sensor is described herein. The LiDAR sensor can comprise a fiber optic ending, a laser assembly, and one or more processors. The fiber optic ending can comprise a fiber optic cable terminated by a reflector. The laser assembly can emit a chirp signal to detect an object in an environment. A portion of the chirp signal can be diverted to the fiber optic ending. The one or more processors construct a profile of the chirp signal based on the diverted portion of the chirp signal. The one or more processors determine a best fit curve based on the profile of the chirp signal and one or more parameters associated with the best fit curve. A frequency offset between an emitted chirp signal and a returned chirp signal can be computed based on the best fit curve and the one or more parameters. Based on the frequency offset, the one or more processors can determine a range of the object.