Two-Step Lidar Return Calibration for Bright-Object Cross-Talk

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Solution Overview

Problem

High reflectivity objects cause significant cross-talk between neighboring lidar channels, complicating the production of high-quality point cloud data, especially in autonomous vehicles, due to the challenges of channel density and listening time, which existing mitigation strategies struggle to manage effectively.

Innovation Solution

A two-step, hardware-accelerated process involving an optical receiver with a hardware accelerator module that quickly identifies bright objects and triggers an interrupt for pulse calibration, allowing for high-quality point cloud data production by managing cross-talk through active mitigation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If channel density and listening time are increased to capture more lidar returns from distant objects, then the ability to detect distant objects is improved, but cross-talk from bright retroreflector objects worsens

Engineering Contradiction:

Improvedetection capability for distant objectsVSAvoidcross-talk from bright objects

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The system performs preliminary classification of lidar returns to identify bright objects before they cause significant cross-talk. The hardware accelerator detects bright returns in real-time and triggers mitigation actions proactively, preventing the cross-talk problem from escalating while maintaining high channel density and listening time for distant object detection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback loop where lidar returns are continuously monitored, bright objects are detected and classified, and mitigation actions are triggered based on this feedback. The system adjusts emission patterns dynamically in response to detected bright objects, creating a closed-loop control system that adapts to changing conditions while maintaining optimal detection performance

Inventive Principle:

Principle #23Feedback

2Measurement precision

If sophisticated calibration algorithms are applied to compensate for systematic artifacts, then data quality is improved, but the time available for cross-talk mitigation decisions decreases

Engineering Contradiction:

Improvepoint cloud data qualityVSAvoiddecision time for cross-talk mitigation

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The calibration and mitigation process is segmented into distinct phases: initial bright object detection by the hardware accelerator, preliminary classification of returns, triggering of mitigation actions, and subsequent sophisticated calibration algorithms. This segmentation allows time-critical detection to occur first, followed by computationally intensive calibration, ensuring both rapid response and high data quality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system replaces software-based detection with a hardware accelerator for initial bright object identification. This hardware implementation provides deterministic, real-time performance that software alone cannot achieve, freeing up processing time for sophisticated calibration algorithms while maintaining rapid mitigation response

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If hardware acceleration is used to rapidly identify bright objects, then mitigation response time is improved, but system complexity increases

Engineering Contradiction:

Improvebright object detection speedVSAvoidoptical receiver architecture

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The hardware accelerator serves as an intermediary component between the photodetectors and the main processing system. It performs specialized bright object detection functions and triggers mitigation actions without requiring full system complexity to be optimized for this specific task, providing rapid response while maintaining modular architecture

Inventive Principle:

Principle #24Intermediary (Mediator)

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 rapid decision-making to mitigate cross-talk from bright objects while maintaining high-quality lidar data, improving the reliability of autonomous vehicle navigation and object detection.

Implementation Method 1

An optical receiver includes a plurality of photodetectors and a shared memory

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS20250321325A1Two-Step Return Calibration for Lidar Cross-Talk Mitigation

Publication Date: 2025.10.16 WAYMO LLC

AI summary

An optical receiver includes a plurality of photodetectors, a shared memory, and a pulse calibration processing unit communicatively coupled to the shared memory. The optical receiver also includes a hardware accelerator module configured to accept input waveforms from the plurality of photodetectors and compare an amplitude of the respective input waveforms with a predetermined threshold. Based on the comparison, the hardware accelerator module could determine subsets of the input waveforms and determine information indicative of characteristic aspects of the subsets of the input waveforms. The optical receiver is additionally operable to store the determined information in the shared memory and trigger an interrupt for the pulse calibration processing unit to initiate a pulse calibration process on the determined information.