LIDAR Pulse Dithering for Range Aliasing Disambiguation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LIDAR devices face range aliasing issues, where they cannot disambiguate between signals scattered from different ranges, leading to ambiguous echoes and incorrect object detection, particularly when objects are outside the nominal unambiguous detection range.
Innovation Solution
The implementation of a computing system that operates LIDAR devices to emit light pulses with a time-varying dither sequence, generating multiple range hypotheses to disambiguate return signals and accurately determine the range of objects, including those beyond the nominal detection range by selecting between close and far range hypotheses based on similarity and recognition of known objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LIDAR device uses a fixed detection period for each emitted light pulse, then the device operation is simple and straightforward, but range aliasing occurs causing ambiguous echoes when objects are outside the nominal unambiguous detection range
Solution Approach 1:
The patent applies dynamics by making the detection period variable rather than fixed. The detection period is dynamically adjusted based on the emitted light pulse timing, creating a time-varying detection scheme that resolves range aliasing ambiguity while maintaining system reliability
Solution Approach 2:
The patent changes the detection period parameter over time to disambiguate range measurements. By varying the detection period according to the emitted light pulse timing, the system can distinguish between objects at different ranges that would otherwise produce ambiguous echoes with a fixed detection period
2Reliability
If LIDAR device assumes each return signal corresponds to the most recently emitted pulse, then processing is simplified, but objects outside the maximum unambiguous detection range cannot be detected
Solution Approach 1:
The patent segments the range detection problem by generating multiple discrete range hypotheses (e.g., first range hypothesis, second range hypothesis) instead of assuming a single correspondence between return signals and emitted pulses. This segmentation allows the system to evaluate multiple possible origins for each return signal
Solution Approach 2:
The patent uses feedback by evaluating multiple range hypotheses and selecting the most likely one based on consistency checks. The system generates hypotheses about which emitted pulse corresponds to each return signal, then uses feedback from the detection results to refine and select the correct range interpretation
3Reliability
If LIDAR device uses a single detection period per pulse, then the system operates efficiently with minimal processing, but range aliasing causes false object detection
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple range hypotheses before actual detection and measurement occur. The system prepares multiple possible interpretations of range data in advance, allowing for efficient processing during actual operation without requiring complex real-time calculations
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 approach effectively resolves range aliasing, enabling accurate detection of objects within and outside the nominal detection range, improving the reliability of LIDAR systems in autonomous vehicle navigation by reducing false object detection and enhancing object recognition.
Implementation Method 1
detecting a returning pulse, if any, reflected from an object in the environment
Implementation Method 2
determining the distance to the object according to the time delay between the transmitted pulse and the reception of the reflected pulse
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.