Radar-Camera Image Synchronization for Timing Error Correction

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Solution Overview

Problem

Existing synchronization methods for radar sensors and external cameras in vehicles suffer from delays and errors in image signal timing due to path delays, leading to inaccurate synchronization.

Innovation Solution

A synchronization device and method that includes a synchronization prediction unit, change amount calculation unit, image estimation unit, and difference extraction unit to predict and correct synchronization errors by estimating a synchronization timing based on calculated change amounts and comparing radar and camera images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If synchronization is performed using path delay information, then synchronization can be achieved, but synchronization accuracy deteriorates due to delays and errors in image signal timing

Engineering Contradiction:
Improvesynchronization accuracyVSAvoidtiming accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the conventional method of using path delay information (mechanical/electrical signal timing) with an image-based synchronization method. By comparing actual image content between radar and camera sensors, the system determines synchronization status without relying on timing signals that are subject to delays and errors.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces image content as an intermediary to determine synchronization status. Instead of directly measuring timing relationships between sensors, the system uses the visual information captured in images as a mediator to infer whether sensors are synchronized, thereby avoiding the inaccuracies of direct timing measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If image-based synchronization is performed, then timing accuracy is improved, but device complexity increases due to additional processing units

Engineering Contradiction:
Improvesynchronization precisionVSAvoidprocessing system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the image processing system multi-functional by using the same image data for both the primary function (visual recognition) and the synchronization function. The image comparison process leverages existing image processing capabilities to simultaneously achieve visual analysis and timing synchronization, avoiding the need for entirely separate dedicated hardware.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system performs self-synchronization by automatically comparing its own captured images and adjusting timing based on the comparison results. The radar and camera sensors use their own image outputs to determine and correct their relative timing, eliminating the need for external synchronization equipment or complex control systems.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS12422552B2Synchronization device, synchronization method, and synchronization program
Publication Date: 2025.09.23 DENSO CORP
  • US12422552B2 patent drawing
  • US12422552B2 patent drawing
  • US12422552B2 patent drawing

AI summary

A synchronization device includes a synchronization prediction unit, a change amount calculation unit, an image estimation unit, a difference extraction unit, and a determination unit. The synchronization prediction unit is configured to predict a synchronization error time between a radar sensor and an external camera. The change amount calculation unit is configured to calculate a change amount of the reflected wave image in a shutter frame of the external camera. The image estimation unit is configured to estimate the reflected wave image for a synchronization timing that is shifted from a start timing of the shutter frame by the synchronization error time. The difference extraction unit is configured to extract a difference by comparing the reflected wave image for the synchronization timing with the outside light image. The determination unit configured is to determine, based on the difference, whether to return to a step of predicting the synchronization error time.