On-board Camera Water Droplet Detection and 3D Object Tracking

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Solution Overview

Problem

Existing on-board monitoring devices for vehicles that use CCD cameras face a challenge in detecting rain droplets and three-dimensional objects simultaneously, as switching focal points leads to periods of non-detection.

Innovation Solution

A water droplet detection device that identifies and controls vehicle systems based on the attachment of water droplets on the camera's optical system, allowing for continuous detection of three-dimensional objects without false positives due to rain droplets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the focal point distance of the lens is switched to detect rain droplets, then water droplet detection capability is improved, but detection continuity deteriorates due to switching periods

Engineering Contradiction:
Improvewater droplet detection capabilityVSAvoiddetection continuity
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent divides the detection function into two separate camera units: one dedicated to water droplet detection with a first focal point distance, and another for three-dimensional object detection with a second focal point distance. This segmentation allows each camera to operate continuously at its optimal focal setting without requiring switching, thereby resolving the contradiction between detection precision and detection continuity.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If the lens focal point is switched between near and far distances, then both rain droplet and periphery detection are enabled, but object detection reliability deteriorates during switching

Engineering Contradiction:
Improvedetection rangeVSAvoidobject detection reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent creates two independent detection systems with dedicated cameras for different functions: water droplet detection and three-dimensional object detection. Each system maintains its own focal point setting continuously, eliminating the reliability issues caused by focal switching while preserving the ability to detect both rain droplets and peripheral objects.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a single imaging device (camera system) that performs multiple detection functions simultaneously through the use of two camera units with different focal point distances. This multi-functionality allows the system to detect both water droplets and three-dimensional objects continuously without compromising reliability in either function.

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

3Device complexity

If a single camera is used for both water droplet and three-dimensional object detection, then device complexity is reduced, but detection precision deteriorates due to focal switching requirements

Engineering Contradiction:
Improvecamera system structureVSAvoiddetection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the imaging function into two separate camera units, each optimized for a specific detection task. This segmentation increases device complexity slightly but significantly improves detection precision by eliminating the need for focal switching, as each camera operates continuously at its dedicated focal point distance.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2879369B1Water droplet detection device and three-dimensional object detection device using water droplet detection device
Publication Date: 2018.10.31 NISSAN MOTOR CO LTD
  • EP2879369B1 patent drawingFigure 1
  • EP2879369B1 patent drawingFigure 2
  • EP2879369B1 patent drawingFigure 3

AI summary

The present invention is provided with: an image capturing means (10) having an photographic optical system (11) and adapted for capturing an image of a predetermined area, an image conversion means (31) for viewpoint-converting an image obtained by the image capturing means to create a bird's-eye-view image; a water droplet detection means (40) for setting an arbitrary attention point in the image, a plurality of first reference points inside an imaginary circle of a predetermined radius having the attention point as the center thereof, and a plurality of second reference points corresponding to the first reference points outside the imaginary circle, detecting edge information between the first reference points and second reference points, and assessing the circularity strength of these edge information, thereby detecting water droplets attached to the photographic optical system; a first three-dimensional object detection means (33) for generating differential waveform information from the differential image of the bird's-eye-view images at different points in time obtained by the image conversion means and detecting a three-dimensional object based on the differential waveform information; a three-dimensional object assessment means (38) for assessing whether the three-dimensional object that has been detected by the first three-dimensional object detection means is another vehicle; a water droplet removal device (41) for removing water droplets attached to the photographic optical system; and a control unit (39) for operating the water droplet removal means in accordance with the water droplet attachment state detected by the water droplet detection means.