WO2015165448A1

WO2015165448A1 - Device for detecting precipitation for a motor vehicle

Info

Publication number: WO2015165448A1
Application number: PCT/DE2015/200212
Authority: WO
Inventors: Christopher Kosubek
Original assignee: Conti Temic Microelectronic Gmbh
Priority date: 2014-04-29
Filing date: 2015-03-31
Publication date: 2015-11-05
Also published as: DE102014207994A1; DE112015000652A5

Abstract

The invention relates to a device and to a method for detecting precipitation for a motor vehicle. The device comprises a camera device which is arranged behind a windscreen and is configured to record a first image of the surroundings of the motor vehicle and a second image, chronologically following the first image, of the surroundings of the motor vehicle; and an evaluation device which is configured to determine, on the basis of a comparison of the first image with the second image, a change in brightness in at least a partial region of the second image, and to detect precipitation adhering to the windscreen on the basis of the determined change in brightness.

Description

Device for detecting precipitation for a motor vehicle

Technical area

The present invention relates to a rain sensor for a motor vehicle. In particular, the present invention relates to an apparatus and a method for detecting precipitation for a motor vehicle.

Technical background

Objects or particles on the windshield of a

Motor vehicles are difficult to recognize in the camera image of a built-in motor vehicle optical camera due to the focus of the long-range.

Accordingly, a raindrop adhering to the windshield with almost transparent properties can hardly be extracted from the image taken by the camera by means of image processing.

Summary of the invention

It can be regarded as an object of the present invention to increase the efficiency of a precipitation or rain detection for the motor vehicle. This task is governed by the objects of the independent

Claims solved. Embodiments and further developments can be taken from the dependent claims, the description and the figures. A first aspect of the invention relates to a device for detecting precipitation for a motor vehicle.

The device comprises: a camera device which is arranged behind a pane and which is designed to display a first image of the surroundings of the motor vehicle and a second image of the surroundings of the surroundings of the first image temporally following

Motor vehicle record; and an evaluation device which is designed to determine a change in brightness in at least one subregion of the second image based on a comparison of the first image with the second image and to detect precipitation adhering to the disk based on the determined brightness change.

In other words, at least two temporally successive images of the surroundings of the motor vehicle are taken by the camera device.

According to a second aspect of the present invention, a method for detecting precipitation for a motor vehicle is provided. The method comprises the following steps: taking a first image of the surroundings of the motor vehicle and a second image temporally following the first image with the aid of a camera device; Determining a brightness change in at least a portion of the second image based on comparing the first image with the second image; and detecting the precipitate adhering to the disc based on the determined brightness change.

Advantageous embodiments of the invention are in the

Subclaims characterized. The present invention is characterized by the fact that raindrop detection can be carried out directly from the recorded camera image, ie passively or without an additional illumination source.

The method of the present invention utilizes the effect of the brightness increases that are caused by drops on the windshield. These brightness and intensity increases are distributed almost uniformly on all pixels of the recorded image.

The idea underlying the present invention lies in the separation of the brightness and color changes in the

recorded image. This separation of the brightness changes from the color changes advantageously enables raindrops and moving background objects to be separated in image analysis.

Another advantage of the present invention is the raindrop recognition derived directly from the image. According to the present invention, lighting is the

Windshield about by light emitting diodes, short LED of English light-emitting diode, German light-emitting diode, even luminescent diode, or other additional light source not required.

Another advantage of the present invention is that the detection area used for rain detection is increased many times.

In other words, a core idea of the present invention can be seen in modeling a raindrop as a lens on the windshield. This lens bundles the light from a lens covered by the lens

Partial area, where the focused light falls on the camera and causes the brightness or intensity increases.

Therefore, it is possible to determine only the brightness change within this subarea and to ignore any color changes or color changes in this area.

The raindrops primarily cause a change in brightness (dL *), but also the color change (da *, db *) is considered to find out whether there is also a color change in addition to the brightness change caused by the raindrop.

If so, the subregion in the image is marked as a colored background object and discarded as a possible drop, since the color change does not correspond to the drop model. Ie. A coincident brightness and color change has another cause and does not correspond to any one on the

Windshield deposited raindrops.

In other words, the consideration of the color change is used to verify the drop model if there is no color change in the partial area, or to discard if there is a color change in the partial area.

Under the vehicle, for example, a passenger car or a truck can be understood. The camera device can be designed as an infrared camera or another camera. The camera device can also be designed to record a plurality of images, a video and / or an image sequence of the surroundings of the vehicle. Under the environment of the vehicle, for example, an area of the environment of the vehicle, which lies in the direction of travel of the vehicle can be understood. The camera device can be understood, for example, as a camera for traffic sign recognition or blind spot monitoring or a camera of another driver assistance system. By the evaluation device, for example, a digital signal processor, English, digital signal processor, DSP, understood, which is adapted to a

continuous processing of digital signals z. To allow as audio or video signals ^¬.

In an advantageous embodiment of the present invention

The invention provides that the camera device has a color-sensitive area sensor. The term "color-sensitive" here means that the

Surface sensor has a spectral resolution, which characterizes a number of spectral channels, such as red, green, blue, of the sensor. As a surface sensor, a CCD sensor or a CMOS sensor can be used.

This advantageously enables a broad spectral sensitivity to be achieved, as well as a high dynamic range (ie the ability to be very powerful at the same time)

faint and very bright areas of an image to capture) and the image information is generated digitally.

In an advantageous embodiment it is provided that the color-sensitive area sensor a Bayer matrix or a having another color filter arrangement.

In a further advantageous embodiment of the present invention, it is provided that the evaluation device is designed to perform a color space transformation of the first image and the second image before comparing the first image with the second image and then to the transformed first image with the transformed second image to compare.

This allows a simple way to differentiate between color model and color space.

In an advantageous embodiment of the present invention

The invention provides for the evaluation device to be designed as the color space transformation

Transformation into a L * a * b * color space or in a

LCh color space or in another color space.

This allows in a simple way, an approximation of

Color differences in the color space to make the perception.

In an advantageous embodiment of the present invention

The invention provides that the evaluation device is designed to change the brightness in the at least one subregion of the second image on the basis of a

To verify the absence of a color valence change in the at least one portion of the second image.

Advantageously, viewing the color change allows discarding the drop model if there is a color change in the portion. In an advantageous embodiment of the present invention

The invention provides that the camera device is designed to receive a third image of the surroundings of the motor vehicle.

This advantageously increases the temporal resolving power of the precipitation detection and the detection threshold of

Device with regard to the lowest ever detectable precipitation intensity.

In an advantageous embodiment of the present invention

The invention provides that the evaluation device is designed to check or confirm the determined brightness change in at least one subregion of the second image on the basis of the third image.

This advantageously increases the reliability, i. the formal accuracy or the reliability of the measurements of

Device and helps to avoid measurement errors or measurement errors.

The described embodiments and developments can be combined with each other as desired. Other possible embodiments, developments and

Implementations of the invention also include not explicitly mentioned combinations of features of the invention described above or below with respect to the exemplary embodiments.

Brief description of the figures

The accompanying drawings are intended to provide further understanding of the embodiments of the invention. The enclosed Drawings illustrate embodiments and, together with the description, serve to explain concepts of the invention.

Other embodiments and many of the stated advantages will become apparent with reference to the drawings. The illustrated elements of the drawings are not necessarily

shown to scale to each other.

Show it:

Fig. 1 is a schematic representation of an apparatus for

Detecting liquid precipitation for a motor vehicle according to an embodiment of the

Invention; a schematic representation of a flowchart of a method for detecting liquid precipitation for a motor vehicle according to another embodiment of the invention;

Fig. 2b is a schematic representation of a

Functional block diagram of a method for detecting liquid precipitation according to yet another embodiment of the invention;

Fig. 3a a of a camera device of the device

recorded image of the environment of the motor vehicle to explain the invention;

Fig. 3b shows a camera device of the device

recorded image of the environment of the motor vehicle to explain the invention; 4a shows an image of the surroundings of the motor vehicle taken by a camera device of the device, for explanation of the explanation of the invention;

Fig. 4b shows a camera device of the device

recorded image of the environment of the motor vehicle to explain the explanation of the invention; 5a shows a representation of a color component of an image of the surroundings of the motor vehicle after a color space transformation to explain the invention;

Fig. 5b is a representation of a color component of an image of the environment of the motor vehicle after a

Color space transformation to explain the invention;

5c shows a representation of a color component of an image of the surroundings of the motor vehicle after a color space transformation in order to explain the invention;

6a shows a representation of a color component of an image of the surroundings of the motor vehicle after a color space transformation in order to explain the invention;

6b shows a representation of a color component of an image of the surroundings of the motor vehicle after a color space transformation in order to explain the invention; and

Fig. 6c is a representation of a color component of an image of the environment of the motor vehicle after a color space transformation to explain the invention. Detailed description of embodiments

In the figures of the drawings, like reference characters designate like or functionally identical elements, components, components or method steps, unless indicated otherwise.

The term "precipitation" can refer to any form of rain or water that falls to the earth after condensation of water vapor due to gravity.

The term "precipitation" includes, for example, rain or liquid precipitation, dust and aerosols that have risen into the atmosphere and on the windshield as quasi-transparent, because outside the depth of field of the camera, deposit or precipitate.

Furthermore, solid precipitate, for. As hail, sleet or snow, be included, which occurs mixed with rain or liquid only after the decline on the windshield.

1 shows a schematic representation of a device for detecting liquid precipitate for a motor vehicle according to an embodiment of the invention.

A device 100 for detecting liquid precipitation for a motor vehicle comprises, for example, a camera device 10 arranged behind a pane and an evaluation device 20 coupled to the camera device 10.

The camera device 10 may be designed to have a first image of the surroundings of the motor vehicle and a first image temporally following second image of the surroundings of the motor vehicle record.

The camera device 10 is designed to record images of the surroundings of the motor vehicle within a specific image angle which defines the field of view 11.

The evaluation device 20 may be designed to change the brightness in at least one of the first image and the second image based on a comparison of the first image

Determine part of the second image and to capture on the basis of the determined change in brightness adhering to the disc, liquid precipitate. Furthermore, the evaluation device 20 can also be realized in the form of an application-specific integrated circuit or in the form of a "Field Programmable Gate Array" (FPGA), ie, for example in the form of an integrated circuit (IC) of digital technology into which a logic circuit is programmed The English name can be translated as: in the (application) field programmable (logic) gate arrangement.

FIG. 2a shows a method for detecting liquid precipitation for a motor vehicle.

The method for detecting liquid precipitation comprises the following steps: A first image of the environment of the motor vehicle and a second image temporally following the first image with the aid of a camera device are taken as a first step of the method. As a second step of the method, a determination S2 of a brightness change takes place in at least a partial area of the second image based on a comparison of the first image with the second image.

As a third step of the method, a detection S3 of the liquid precipitate adhering to the pane takes place on the basis of the ascertained change in brightness.

FIG. 2b shows a schematic representation of a

Functional block diagram of a method for detecting liquid precipitation according to yet another embodiment of the invention.

A first image II and a second image 12 are taken by the chamber device 10, wherein the second image 12 was taken in time to the first image II. In a first functional block S21, a

Color space transformation, for example in the form of a

Transformation into a L * a * b * color space or in a

LCh color space or in another color space. In a second functional block S22, the images are separated into color space components, for example into a dL * channel, into a da * channel and into a db * channel in the event of a transformation into the L * a * b * color space. A representation or image analysis of the dL * channel is performed in a function block S31, a representation or image analysis of the da * channel in a function block S32 and a representation or image analysis of the db * channel in a function block S33. FIG. 3 a shows an image of the surroundings of the motor vehicle taken by a camera device of the device to explain the invention.

The image shown in FIG. 3a is a first image of the surroundings of the motor vehicle. The first image has a partial region 5, three raindrops falling down from above, but not yet falling down on the windshield in FIGS. 3a and 3b.

FIG. 3b shows an image of the surroundings of the motor vehicle taken by a camera device of the device to explain the invention.

The image shown in FIG. 3b is a second image of the surroundings of the motor vehicle. The second image has a subregion 5. In the embodiments of Figures 3a and 3b, there is no raindrop on the windshield.

These embodiments serve to illustrate the color changes that are represented by moving objects (here: barrier moves upwards) in all three channels (dL *, da * and db *). The raindrop, as in the

Embodiments of Figures 4a and 4b shown, however, is noticeable by the sole change in brightness only in dL *. FIG. 4a shows an image of the surroundings of the motor vehicle taken by a camera device of the device, for explanation of the explanation of the invention. The image shown in FIG. 4a is a first image of the surroundings of the motor vehicle. The first image has a subregion 5. FIG. 4b shows an image of the surroundings of the motor vehicle taken by a camera device of the device for explaining the invention.

The image shown in FIG. 4b shows a raindrop adhering to the windshield.

Figures 3a and 3b and 4a and 4b show two independent events: Figures 3a and 3b show only background change by moving objects, such as an opening barrier of a parking garage or a railroad crossing without raindrops.

Figures 4a and 4b, in contrast, show no

Background change, i. no moving objects, but in the time offset between the figures 4a and 4b, a rain drops in the field of view of the camera, such as the windshield of the motor vehicle. FIG. 5a shows a representation of a color component of an image of the surroundings of the motor vehicle according to FIG

Color space transformation to explain the invention.

FIG. 5a shows a dL * channel of the first image as shown in FIGS. 3a and 3b. Here, the absolute difference between the transform (LI *) of the first image of Figure 3a and the transform (L2 *) of the second image of Figure 3b is shown. In short: dL * = | LI * - L2 * | ,

The same applies to a * and b *: da * = I al * - a2 * | , db * = | bl * - b2 * | , FIG. 5b shows a representation of a color component of an image of the surroundings of the motor vehicle according to FIG

Color space transformation to explain the invention.

FIG. 5b shows a da * channel of the first image as shown in FIGS. 3a and 3b.

FIG. 5 c shows a representation of a color component of an image of the surroundings of the motor vehicle according to FIG

Color space transformation to explain the invention.

FIG. 5c shows a db * channel of the first image as shown in FIGS. 3a and 3b.

FIG. 6a shows a representation of a color component of an image of the surroundings of the motor vehicle according to FIG

Color space transformation to explain the invention.

FIG. 6a shows a dL * channel of the second image as shown in FIGS. 4a and 4b.

FIG. 6b shows a representation of a color component of an image of the surroundings of the motor vehicle according to FIG

Color space transformation to explain the invention. FIG. 6b shows a da * channel of the second image, as shown in FIGS. 4a and 4b. FIG. 6c shows a representation of a color component of an image of the surroundings of the motor vehicle according to FIG

Color space transformation to explain the invention.

FIG. 6c shows a db * channel of the second image as shown in FIGS. 4a and 4b.

Although the present invention is based on preferred

Embodiments described above, it is not limited thereto, but modifiable in a variety of ways. In particular, the invention can be varied or modified in many ways without deviating from the gist of the invention.

In addition, it should be noted that "comprising" and "having" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. It should also be appreciated that features or steps described with reference to any of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations.

Claims

claims

1. A device for detecting precipitation for a

Motor vehicle, the device comprising:

a camera device (10) arranged behind a pane, which is designed to produce a first image of the surroundings of the motor vehicle and a second image of the surroundings of the environment which follows the first image in temporal succession

Motor vehicle record; and

- An evaluation device (20) which is adapted to determine based on a comparison of the first image with the second image, a brightness change in at least a portion of the second image and to detect based on the determined change in brightness adhering to the disc precipitation.

2. Device according to claim 1, wherein the camera device (10) comprises a color-sensitive area sensor.

3. Device according to claim 2, wherein the color-sensitive area sensor is a Bayer matrix or another

Having color filter assembly.

4. Device according to one of the preceding claims, wherein the evaluation device (20) is adapted to perform before comparing the first image with the second image, a color space transformation of the first image and the second image and then the transformed first image with the transformed second image to compare.

5. Apparatus according to claim 4, wherein the

Evaluation device (20) is designed as the

Color space transformation a transformation into one

L * a * b * color space or in an LCh color space or in another color space.

6. Device according to one of the preceding claims, wherein the evaluation device (20) is adapted to the

Brightness change in the at least a portion of the second image based on a nonexistence of a

Color change in the at least a portion of the second image to verify.

7. Device according to one of the preceding claims, wherein the camera device (10) is adapted to receive a third image of the environment of the motor vehicle.

8. Apparatus according to claim 7, wherein the

Evaluation device (20) is adapted to confirm based on the third image, the determined brightness change in at least a portion of the second image.

9. Method for detecting precipitation for a

Motor vehicle, the method comprising the steps of:

Picking up (Sl) a first image of the surroundings of the motor vehicle and a second image temporally following the first image with the aid of a first image

Camera device (10); - determining (S2) a brightness change in at least a partial area of the second image based on a comparison of the first image with the second image; and - detecting (S3) the adhering to the disc

Precipitation based on the determined brightness change.

10. The method of claim 9, wherein prior to comparing the first image with the second image

Color space transformation of the first image and the second

Image is performed and then the transformed first image is compared with the transformed second image.