Asymmetrical Lidar Pulses for Multipath Reflection Filtering

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Solution Overview

Problem

Lidar systems face inaccuracies in object detection due to multipath reflections, leading to unsafe operating conditions in environments with complex structures.

Innovation Solution

Employing spatially asymmetrical lidar pulses with varying properties across their cross-sections to differentiate between single and multipath reflections by analyzing intensity, power, polarization, phase, coherence, spectral content, and temporal shape, allowing for accurate object detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional lidar pulses are used for object detection, then the system is simple and easy to operate, but measurement precision deteriorates due to multipath reflections

Engineering Contradiction:

Improveobject detection accuracyVSAvoidpulse structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by transmitting lidar pulses with non-uniform intensity distributions across their cross-sections, such as skewed or asymmetric intensity patterns. This asymmetric structure serves as a fingerprint that remains recognizable after single reflections, enabling the system to distinguish true single-bounce reflections from multipath reflections, thereby improving measurement precision without requiring complex processing

Inventive Principle:

Principle #4Asymmetry

2Reliability

If multipath reflections are not filtered, then the lidar system operates simply, but reliability deteriorates leading to unsafe operating conditions

Engineering Contradiction:

Improveobject detection reliabilityVSAvoidsignal processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses feedback by comparing the intensity distribution pattern of the returned pulse against the known asymmetric pattern of the transmitted pulse. By analyzing whether the returned pulse maintains the characteristic asymmetric intensity distribution, the system can reliably identify single-bounce reflections and filter out multipath reflections, significantly improving detection reliability

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent substitutes complex mechanical or algorithmic filtering systems with a simpler approach based on the physical property of light intensity distribution patterns. Instead of using complex signal processing or multiple sensors, the system leverages the inherent asymmetric intensity pattern of the lidar pulse itself as a discrimination mechanism, reducing processing complexity while maintaining high reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If spatially asymmetrical pulses are used to differentiate single and multipath reflections, then object detection accuracy improves, but device complexity increases

Engineering Contradiction:

Improvereflection type differentiation accuracyVSAvoidpulse generation and detection complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating different intensity characteristics at different locations within the pulse cross-section. Specifically, the transmitted pulse has a non-uniform intensity distribution where certain spatial regions have higher or lower intensities in a consistent asymmetric pattern. This local variation in intensity quality serves as an intrinsic identifier that survives single reflections, enabling accurate differentiation without requiring additional sensors or complex processing

Inventive Principle:

Principle #3Local quality

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 object detection by filtering out multipath reflections, improving safety and efficiency in autonomous vehicle navigation.

Implementation Method 1

lidar systems that use lasers to emit pulses into an environment and sensors to detect pulses that are reflected back from the surfaces of objects in the environment

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

employing spatially asymmetrical lidar pulses with varying properties across their cross-sections to differentiate between single and multipath reflections

Methodology Applied

Scientific EffectLIDAR: LIDAR

Data Source

PatentUS12517221B1Lidar multipath identification using spatially asymmetrical pulses

Publication Date: 2026.01.06 ZOOX INC

AI summary

Techniques for determining whether a reflected lidar pulse has been subject to multipath reflection effects are disclosed. An initially emitted lidar pulse is generated having a property that varies across the pulse (either spatially in cross-section and/or temporally). Detected reflected pulses are analyzed to determine if they have similar or different properties. If the properties of both pulses are similar, the reflected pulse was likely not affected by multipath reflection. If the properties are similar, the reflected pulse likely was affected by multipath reflection. Pulses having a high likelihood of multipath reflections may be discarded (or disregarded) for subsequent processing.