Coherent Range-Doppler LIDAR Odometry for Doppler Ambiguity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LIDAR systems struggle with resolving Doppler detection ambiguity and improving the reliability of optical range measurements for vehicle navigation, particularly in autonomous systems where multiple sensors may behave unreliably.
Innovation Solution
Implementing high-resolution range-Doppler LIDAR systems that utilize coherent processing to detect Doppler shifts and correct cross-correlation calculations, enabling accurate range and relative speed measurements, and integrating these systems with other sensors for reliable vehicle navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LIDAR systems are used for vehicle navigation, then the system structure is simple, but the measurement precision and reliability of range measurements deteriorate due to Doppler detection ambiguity
Solution Approach 1:
The patent implements dynamic scan direction switching where the LIDAR system alternates between unidirectional and bidirectional scanning modes. This dynamic adaptation allows the system to resolve Doppler ambiguity by comparing velocity measurements from different scan directions, thereby improving range measurement precision without requiring a fundamentally more complex system architecture
Solution Approach 2:
The system employs periodic bidirectional scanning interspersed with unidirectional scans. By periodically switching scan directions and using the returned signals from opposite directions to detect and correct Doppler shifts, the system achieves higher measurement precision through time-periodic measurement sequences rather than continuous complex processing
2Reliability
If unidirectional scanning is used, then the device complexity is reduced, but the reliability of velocity measurements deteriorates due to discontinuities in velocity data
Solution Approach 1:
The patent intentionally introduces asymmetry in the scanning pattern by alternating between unidirectional and bidirectional scans. This asymmetric scan sequence creates complementary velocity measurement data sets that, when combined, eliminate the discontinuities and reliability issues inherent in purely unidirectional scanning
Solution Approach 2:
The system uses feedback from bidirectional scan results to correct and validate velocity measurements obtained during unidirectional scans. By comparing velocity data from opposite scan directions and using the average velocity as a reference, the system continuously refines its velocity measurements, improving reliability through self-validation feedback loops
3Reliability
If bidirectional scanning is used, then the velocity measurement reliability is improved through average velocity calculation, but the loss of time increases due to additional scan operations
Solution Approach 1:
The patent implements a hybrid scanning strategy where bidirectional scans are performed only periodically rather than continuously. Unidirectional scans handle most of the mapping operations, while bidirectional scans are inserted at intervals to provide reliability calibration. This partial use of bidirectional scanning achieves velocity measurement reliability improvement with minimal additional time cost
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
Enhances the accuracy and reliability of vehicle navigation by resolving Doppler ambiguity and ensuring consistent performance of LIDAR systems, even when other sensors fail, thereby improving vehicle localization and control.
Implementation Method 1
chirped detection based on a frequency difference between a transmitted chirped optical signal and a returned signal scattered from an object
Implementation Method 2
direct ranging based on round trip travel time of an optical pulse to an object
Data Source
AI summary
A system and method for vehicle odometry using coherent range Doppler optical sensors. The system and method includes operating a Doppler light detection and ranging (LIDAR) system to collect raw point cloud data that indicates for a point a plurality of dimensions, wherein a dimension of the plurality of dimensions includes an inclination angle, an azimuthal angle, a range, or a relative speed between the point and the LIDAR system; determining a corrected velocity vector for the Doppler LIDAR system based on the raw point cloud data; and producing revised point cloud data that is corrected for the velocity of the Doppler LIDAR system.