LIDAR Pulse Dithering for Range Aliasing Disambiguation
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Solution Overview
Problem
Range aliasing in LIDAR devices leads to ambiguous echoes, making it difficult to distinguish between signals scattered from within and outside the maximum unambiguous range, particularly when detecting objects beyond the nominal detection range.
Innovation Solution
Implementing a time-varying dither in the emission sequence of LIDAR pulses and generating multiple range hypotheses to disambiguate return signals, allowing the system to select the most likely range hypothesis for object detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a LIDAR device uses a fixed maximum unambiguous range for detection, then the device complexity is reduced and operation is simplified, but range aliasing occurs making it impossible to distinguish objects inside versus outside the maximum unambiguous range
Solution Approach 1:
The patent applies dynamics by making the maximum unambiguous range variable rather than fixed. The system dynamically adjusts the maximum unambiguous range based on detected objects and environmental conditions, allowing the LIDAR to adapt its detection parameters in real-time. This resolves the contradiction by enabling accurate range detection for both near and far objects without requiring a completely complex multi-range system, as the parameters are adjusted dynamically based on operational needs.
Solution Approach 2:
The patent changes the parameter of maximum unambiguous range from a fixed value to a variable parameter that can be adjusted based on detection requirements. By modifying this key parameter dynamically, the system can accurately detect objects at different ranges without suffering from range aliasing, while avoiding the need for a completely complex multi-range detection architecture.
2Adaptability or versatility
If the LIDAR detection range is extended beyond the maximum unambiguous range, then the detection capability is improved, but range aliasing causes ambiguous echoes that reduce measurement precision
Solution Approach 1:
The system dynamically adjusts the maximum unambiguous range parameter based on the detection scenario. When objects are detected beyond the current maximum unambiguous range, the system modifies the parameter to extend the effective detection range while maintaining measurement precision by avoiding range aliasing through coordinated parameter changes.
Solution Approach 2:
The patent extends detection capability by changing the maximum unambiguous range parameter from a fixed limit to an adjustable value. This allows the LIDAR to detect objects beyond the original maximum range while maintaining measurement precision by dynamically setting the parameter appropriate for each detection scenario, thereby eliminating range aliasing issues.
3Measurement precision
If multiple range hypotheses are generated and evaluated, then object detection accuracy beyond nominal range is improved, but the processing time and computational complexity increase
Solution Approach 1:
The system performs preliminary actions by pre-establishing multiple range hypotheses before final object detection and classification. These hypotheses are prepared in advance based on the detected return signals, allowing the system to quickly evaluate and select the most likely range without extensive real-time computation, thereby reducing processing time while maintaining high detection accuracy.
Solution Approach 2:
The patent segments the range detection process into multiple discrete hypotheses (e.g., first range hypothesis, second range hypothesis). Each hypothesis represents a distinct range interpretation, allowing the system to evaluate them separately and efficiently. This segmentation enables parallel or sequential processing of range possibilities without requiring exhaustive analysis of all potential ranges, thus reducing computational complexity and processing time.
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
Resolves range ambiguity by accurately detecting objects outside the nominal detection range and disambiguating multiple return signals, enhancing the accuracy of LIDAR systems in autonomous vehicles.
Implementation Method 1
determining the distance to the object according to the time delay between the transmitted pulse and the reception of the reflected pulse
Implementation Method 2
detecting a returning pulse, if any, reflected from an object in the environment
Data Source
AI summary
A computing system may operate a LIDAR device to emit light pulses in accordance with a time sequence including a time-varying dither. The system may then determine that the LIDAR detected return light pulses during corresponding detection periods for each of two or more emitted light pulses. Responsively, the system may determine that the detected return light pulses have (i) detection times relative to corresponding emission times of a plurality of first emitted light pulses that are indicative of a first set of ranges and (ii) detection times relative to corresponding emission times of a plurality of second emitted light pulses that are indicative of a second set of ranges. Given this, the system may select between using the first set of ranges as a basis for object detection and using the second set of ranges as a basis for object detection, and may then engage in object detection accordingly.