KR102473347B1 - System and Method for Detecting Black Ice - Google Patents

Abstract

In the present invention, a plurality of lidars each mounted at different predetermined positions of a vehicle, emitting light of different predetermined wavelengths, and receiving reflected light to obtain object positions and reflectances, obtained from each of the plurality of lidars. A normalization unit that normalizes the reflectance of light for each wavelength, a pattern analyzer that analyzes the reflectance pattern according to the change in the reflectance of light for each normalized wavelength, and a plurality of lidars match each detected object location to a location on a common space region, and It includes a black ice detection unit that determines whether the detected object is black ice by determining whether the reflectance pattern analyzed for light corresponds to a preset black ice pattern, so as to accurately detect black ice present on the driving route in advance. Provided is a black ice detection system and method capable of preventing accidents caused by black ice in advance by detecting and notifying a driver.

Description

Black ice detection system and method {System and Method for Detecting Black Ice}

The present invention relates to a black ice detection system and method, and relates to a black ice detection system and method capable of accurately detecting black ice using lidar.

Black ice refers to a sheet of thin ice formed on a road by this process, when the temperature drops again after the snow melts, the melted snow freezes again and becomes ice. At this time, the ice is thin and transparent, so the black asphalt color of the road can be seen through, so it is called black ice.

Such black ice is one of the main causes of many traffic accidents in winter because it is almost indistinguishable from asphalt with the naked eye of the driver, and even if it is distinguished, it is easy to think that the road is simply a little wet. In particular, in the case of a traffic accident caused by black ice, the driver is often unaware of the situation until the moment the accident occurs, resulting in a more serious accident than other accidents.

Therefore, there is a demand for a system capable of detecting black ice while driving and notifying the driver.

Korean Registered Patent No. 10-2039487 (registered on October 28, 2019)

An object of the present invention is to provide a black ice detection system and method capable of accurately detecting black ice that is difficult for a driver to visually recognize.

Another object of the present invention is to provide a black ice detection system and method capable of preventing an accident by detecting black ice in advance and notifying a driver.

In order to achieve the above object, a black ice detection system according to an embodiment of the present invention is mounted at different predetermined locations of a vehicle, emits light of different predetermined wavelengths, and receives reflected light to determine the position of an object and reflectance. A plurality of lidar to obtain; a normalization unit normalizing the reflectance of light for each wavelength obtained from each of the plurality of lidars; a pattern analyzer for analyzing a reflectance pattern according to a change in reflectance of light for each normalized wavelength; And matching object positions detected by the plurality of lidars with positions on a common space region, and determining whether the reflectance pattern analyzed for each wavelength of light corresponds to a preset black ice pattern, so that the detected object is black. It includes a black ice detection unit that determines whether it is ice.

Each of the plurality of lidars emits light in a predetermined range to detect an object to obtain an object position and reflectance. Ranges in which the plurality of lidars emit light may partially overlap each other.

The black ice detection unit may detect, as a black ice area, a black ice pattern in which the magnitudes of reflectances of at least two or more of the plurality of lidars are reversed from each other in an area where the plurality of lidars overlap and detect.

The normalization unit may normalize the reflectance of light for each wavelength on a dry road surface to have the same reference reflectance.

The plurality of LiDARs may emit light of designated wavelengths in a Near InfraRed (NIR) range and a Middle InfraRed (MIR) range, respectively, or may emit lights of different wavelengths in the NIR range.

The black ice detection system may further include a warning output unit for visually or audibly notifying the vehicle driver of the detected black ice area when the black ice area is detected.

A method for detecting black ice according to another embodiment of the present invention for achieving the above object uses a plurality of lidars mounted at different predetermined locations of a vehicle and emitting light of different predetermined wavelengths, respectively. In the detection method, the step of obtaining the object position and reflectance by receiving the reflected light of the light of the corresponding wavelength, each of the plurality of lidar; Normalizing the reflectance of light for each wavelength obtained from each of the plurality of LiDARs; Analyzing a reflectance pattern according to a change in reflectance of light for each normalized wavelength; matching object positions detected by the plurality of lidars with positions on a common space region; and determining whether the detected object is black ice by determining whether the reflectance pattern analyzed for each wavelength of light corresponds to a predetermined black ice pattern.

Therefore, the black ice detection system and method according to an embodiment of the present invention allows a plurality of lidars pre-installed in a vehicle to emit light of different wavelengths and analyzes the reflected light to detect black ice existing on a driving route in advance. Accidents due to black ice can be prevented in advance by accurately detecting and notifying the driver.

1 shows a schematic configuration of lidar.
2 shows a change in reflectance for each environment according to wavelength.
3 shows a schematic structure of a black ice detection system according to an embodiment of the present invention.
FIG. 4 shows an example of a vehicle having the black ice detection system of FIG. 3 .
5 and 6 are diagrams for explaining areas in which the black ice detection system detects black ice.
7 shows a black ice detection method according to an embodiment of the present invention.

In order to fully understand the present invention and its operational advantages and objectives achieved by the practice of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the described embodiments. And, in order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals in the drawings indicate the same members.

Throughout the specification, when a part "includes" a certain component, it means that it may further include other components, not excluding other components unless otherwise stated. In addition, terms such as "... unit", "... unit", "module", and "block" described in the specification mean a unit that processes at least one function or operation, which is hardware, software, or hardware. And it can be implemented as a combination of software.

1 shows a schematic configuration of lidar, and FIG. 2 shows a change in reflectance for each environment according to wavelength.

The black ice detection system according to the present invention detects black ice using lidar, and will first be described with reference to FIGS. 1 and 2 in which lidar operation and lidar can detect black ice.

Referring to FIG. 1 , lidar 10 may schematically include a control calculation unit 11 , a laser output unit 12 and a light receiving unit 13 . The control operation unit 11 first controls the laser output unit 12 so that the laser output unit 12 emits laser light of a predetermined wavelength. The control operation unit 11 analyzes the detection signal applied from the light receiving unit 13 to determine the position of the object 20 .

The laser output unit 12 outputs light of a designated wavelength in a predetermined waveform according to the control of the control calculation unit 11 . At this time, the laser output unit 12 may output light within the vertical and horizontal ranges designated by the control operation unit 11 . The laser output unit 12 may include a single or multiple light sources, and when including a single light source, one light source may emit light while rotating in vertical and horizontal directions within a predetermined range. In addition, when a plurality of light sources are included, laser light may be emitted while rotating in a horizontal direction within a predetermined rotational angle range.

The light receiving unit 13 generates a detection signal by detecting reflected light emitted from the laser output unit 12 and reflected on the object 20 to generate a detection signal, and transfers the generated detection signal to the control operation unit 11 .

The control operation unit 11 may control the laser output unit 12 to emit light of a pulse wave according to a method of detecting an object, and may control the laser output unit 12 to emit light of a phase shift waveform in some cases. When the light of the pulse wave is emitted, the control operation unit 11 determines the direction in which the light is emitted from the laser output unit 12 and the time until the reflected light pulse is detected according to the Time of Flight (ToF) method. It can be used to determine the position of an object. In addition, when the light of the phase shift waveform is emitted, the position of the object can be determined using the direction in which the light is emitted and the amount of phase change of the reflected laser signal. That is, the location information of the object may be acquired.

The control operation unit 11 may obtain a depth map in the form of a point cloud so that a rough outline of an object is displayed based on distance information according to a direction in which light is emitted. In particular, in the present embodiment, the control operation unit 11 may obtain a reflectance indicating a ratio of incident reflected light to emitted light.

Although not shown, the lidar 10 further includes at least one lens for focusing the light output from the laser output unit 12 and the reflected light incident on the light receiving unit 13 depending on the structure, or to refract the path of the light. A structure such as a mirror may be further included.

As such, the lidar 10 generally uses infrared light and may emit light of various predetermined wavelengths. And as shown in Figure 2, the light emitted from the lidar 10 exhibits different reflectance depending on the wavelength of the light and the reflective object.

Figure 2 shows the results of comparing the reflectance of three different wavelengths of light radiated to roads with different wavelengths of 1310 nm, 1430 nm, and 1550 nm, respectively, and reflected and incident. However, there is a basic difference in reflectance depending on the wavelength. Therefore, it is difficult to confirm the change according to each wavelength that appears when reflected from objects in different states with only simple reflectance. Accordingly, the change in reflectance according to the condition of the road surface was confirmed by normalizing the reflectance for each wavelength so that all reflectances in the dry state had the same value of 1.

Referring to FIG. 2 , reflectances for light of three wavelengths appear to be the same value on a dry road surface (Dry) due to normalization. However, on a wet road (water), reflectance for all three wavelengths is lowered, but higher reflectances are shown in the order of 1310nm, 1430nm, and 1550nm wavelengths. In addition, it can be seen that the light of 1310 nm wavelength still shows the highest reflectance on the black ice road, but the reflectance of the light of 1430 nm and 1550 nm wavelengths are reversed. In addition, reflectance is greatly reduced on the road surface (Ice) in a frozen state, and reflectance at 1430 nm and 1550 nm wavelengths is almost lost. That is, it represents a state in which no reflected light is substantially incident. Finally, it can be seen that the reflectance increases significantly on the snow-covered road surface (Snow) than on the dry road surface.

Therefore, according to FIG. 2, it can be seen that the reflectance pattern for each wavelength changes according to the reflective object or the state of the reflective object, in other words, using the change in the normalized reflectance pattern for light of different wavelengths, In particular, it means that black ice can be accurately detected.

3 shows a schematic structure of a black ice detection system according to an embodiment of the present invention, FIG. 4 shows an example of a vehicle equipped with the black ice detection system of FIG. 3, and FIGS. 5 and 6 show black ice detection. It is a diagram for explaining the area where the system detects black ice.

3 to 6, the black ice detection system according to the present embodiment includes a lidar unit 110, a normalization unit 120, a pattern analysis unit 130, a black ice detection unit 140, and a warning output unit 150. ) may be included.

The lidar unit 110 includes a plurality of lidars, and each of the plurality of lidars emits light of a different wavelength having a predetermined pattern, and the light emitted at each wavelength is reflected on an object to generate the incident reflected light. By sensing, the position information of the object and the reflectance of the emitted light are acquired. Here, the light emitted from the plurality of lidars may be designated to have wavelengths respectively corresponding to the NIR (Near InfraRed) range and the MIR (Middle InfraRed) range, or may be designated to have different wavelengths in the NIR range. Here, as an example, as shown in FIGS. 5 and 6, two lidas 111 and 112 or three lidas 113 to 115 each have a different wavelength of 1310 nm, 1430 nm, and 1550 nm. Assume.

Since the black ice detection system according to the present embodiment should be able to detect black ice and notify the driver, it is provided in the vehicle as shown in FIG. 4 . In particular, as shown in FIGS. 5 and 6 , the plurality of lidars 111 to 115 of the lidar unit 110 may be disposed at predetermined locations (eg, the front of the vehicle), and overlap each other. It can be arranged to have a detection area.

LiDAR is an essential trend for self-driving vehicles that have been actively researched recently. The lidar is configured to detect an object by rotating a single radar in all directions of 360 degrees, so that only one lidar may be provided in the vehicle, but in this case, there is a problem that the mounting position of the lidar in the vehicle is limited, and in various environments There is a limitation that it is difficult to obtain object location information with high reliability.

Therefore, in order to accurately recognize the surrounding situation, a plurality of lidars must be installed in the vehicle, and the plurality of lidars must use light of different wavelengths so that object misrecognition does not occur due to light emitted from other lidars.

That is, in the future autonomous vehicles may be provided with a plurality of lidars that use light of different wavelengths. And, in the black ice detection system of the present invention, the lidar unit 110 may be configured to detect black ice using a plurality of lidars already provided in an autonomous vehicle or the like.

However, in the case of the existing LIDAR, most of the information from reflected light reflected from the road was ignored as it was set to mainly detect obstacles while driving the vehicle. However, in the case of the present invention, since black ice formed on the road should be detectable, all location information obtained from reflected light reflected from the road is utilized. In particular, the reflectance of the reflected light with respect to the emitted light for each location is obtained.

The normalization unit 120 normalizes the reflectance obtained from the lidar unit 110 according to a predetermined method. As the plurality of lidars 111 to 115 of the lidar unit 110 are configured to emit light of different wavelengths, as described above, even if light is reflected from the same object, the reflectance is different from each other according to the wavelength.

Accordingly, in order to accurately detect black ice, as shown in FIG. 2, reflectances for light of different wavelengths need to be normalized, and here, reflectances for each wavelength also have the same reference reflectances as reflectances in dry conditions. normalize Since various normalization techniques are already known, detailed descriptions are omitted here.

The pattern analysis unit 130 analyzes the reflectance pattern for each wavelength normalized by the normalization unit 120 . That is, the pattern analyzer 130 analyzes the change pattern of the reflectance for each wavelength that varies according to the road surface condition, and transmits it to the black ice detector 140 .

The black ice detection unit 140 determines an area where black ice has occurred on the road surface based on the object position obtained from the lidar unit 110 and the reflectance pattern change obtained from the pattern analysis unit 130 . That is, it is determined whether an object existing at an object position obtained from a plurality of lidars is black ice. At this time, the black ice detection unit 140 matches the location information that is detected by the plurality of lidars 111 to 115 disposed in different locations of the vehicle and appears in different virtual space areas to become location information of the same space area, Positional information of an object may be obtained. In addition, the black ice detection unit 140 changes the reflectance of the reflected light according to the light of each wavelength in the area where the plurality of lidars 111 to 115 of the lidar unit 110 overlap and detect each other, that is, the reflectance pattern is black ice. Black ice is detected by analyzing whether it corresponds to black ice, and an area showing a reflectance pattern corresponding to black ice is identified and detected as a black ice area.

When the black ice detection unit 140 detects an area where black ice exists, the warning output unit 150 notifies the driver of the detected black ice generating area according to a predetermined method. Here, when black ice is detected, the warning output unit 150 not only outputs a warning to the driver audibly using a speaker, etc., but also allows the driver to visually display an area where black ice is detected using a display device or the like. make it possible to check

As a result, the black ice detection system according to the present embodiment can accurately detect whether and where black ice has occurred using a plurality of lidars provided in the vehicle and notify the driver of the occurrence of black ice while the driver is driving. area can be avoided. In addition, even if it is difficult to avoid the area where black ice has occurred, the driver can recognize the existence of black ice in advance, so the possibility of an accident can be greatly reduced by taking precautionary measures such as slowing down, and it is possible to prevent it from expanding into a large-scale accident. can

In particular, in the case of a self-driving vehicle, it is possible to prevent accidents in the self-driving vehicle itself by notifying the autonomous driving system of the black ice area, and by sharing the black ice area with surrounding vehicles through the network, even the occurrence of accidents in other vehicles It can be prevented.

7 shows a black ice detection method according to an embodiment of the present invention.

Referring to FIGS. 1 to 6 , the black ice detection method of FIG. 7 will be described. First, a plurality of LiDARs 111 to 115 disposed at different predetermined locations of the vehicle 100 have different predetermined wavelengths. Emitting light and detecting the reflected light (S10). In addition, each of the plurality of lidars 111 to 115 analyzes reflected light of a corresponding wavelength to obtain a relative position and reflectance of an object that reflects the emitted light based on each lidar (S20).

When the relative position and reflectance of an object are obtained from the plurality of lidars 111 to 115, the reflectance obtained according to light of different wavelengths is normalized according to a predetermined method, and a pattern of changes in the normalized reflectance is analyzed. (S30).

On the other hand, since the object position detected by each of the plurality of lidars 111 to 115 is a relative position in space based on the corresponding lidar, the lidar arranges the object position detected by each lidar 111 to 115 Based on the position difference, matching is performed in a common space (S40).

Then, the black ice pattern is confirmed based on the reflectance change pattern analyzed for a plurality of lights of different wavelengths (S50). At this time, the black ice pattern may be detected in an area where at least two or more lidars of the plurality of lidars 111 to 115 overlap and sense. This is because, as shown in FIG. 2 , it is difficult to accurately detect a wet road surface or an icy road surface and black ice only with reflectance of light of a single wavelength.

Meanwhile, it is determined whether black ice is detected as a result of the check (S60). That is, it is determined whether the object detected by lidar is black ice. If black ice is detected, an area where black ice is detected is checked and a warning is output (S70). At this time, the area where the black ice is detected may be output as an auditory warning to the driver or visually displayed.

The method according to the present invention may be implemented as a computer program stored in a medium for execution on a computer. Here, computer readable media may be any available media that can be accessed by a computer, and may also include all computer storage media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, including read-only memory (ROM) dedicated memory), random access memory (RAM), compact disk (CD)-ROM, digital video disk (DVD)-ROM, magnetic tape, floppy disk, optical data storage device, and the like.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is only exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

10: lidar 11: laser output unit
12: laser output unit 13: light receiving unit
20: object 100: vehicle
110: lidar unit 120: normalization unit
130: pattern analysis unit 140: black ice detection unit
150: warning output unit 200: black ice

Claims (12)

a plurality of lidars mounted at different predetermined locations of the vehicle, respectively emitting light of different predetermined wavelengths and receiving reflected light to obtain an object position and reflectance;
a normalization unit normalizing the reflectance of light for each wavelength obtained from each of the plurality of lidars;
a pattern analyzer for analyzing a reflectance pattern according to a change in reflectance of light for each normalized wavelength; and
The plurality of lidars match each detected object position to a position on a common space region, and determine whether or not the reflectance pattern analyzed for each wavelength of light corresponds to a preset black ice pattern, so that the detected object is black ice. Including a black ice detection unit for determining whether or not
The plurality of lidas
Each detects an object by emitting light in a predetermined range to obtain an object position and reflectance, and the ranges in which the plurality of lidars emit light partially overlap each other,
The black ice detector
A black ice detection system for detecting, as a black ice area, an area appearing as a black ice pattern in which the magnitudes of reflectances of at least two or more of the plurality of lidars are reversed from each other in an area overlapped and sensed by the plurality of lidars.
delete delete The method of claim 1, wherein the normalization unit
A black ice detection system that normalizes the reflectance of light for each wavelength on a dry road surface to the same reference reflectance. The method of claim 1, wherein the plurality of lidar
A black ice detection system that emits light of a specified wavelength in each of the NIR (Near InfraRed) range and MIR (Middle InfraRed) range, or emits light of different wavelengths in the NIR range. The method of claim 1, wherein the black ice detection system
The black ice detection system further comprising a warning output unit for visually or audibly notifying a vehicle driver of the detected black ice area when a black ice area is detected. A black ice detection method using a plurality of lidars mounted at different predetermined locations of a vehicle and emitting light of different predetermined wavelengths, respectively, comprising:
obtaining an object position and reflectance by receiving reflected light of light of a corresponding wavelength by each of the plurality of lidars;
Normalizing the reflectance of light for each wavelength obtained from each of the plurality of LiDARs;
Analyzing a reflectance pattern according to a change in reflectance of light for each normalized wavelength;
matching object positions detected by the plurality of lidars with positions on a common space region; and
Determining whether the detected object is black ice by determining whether the reflectance pattern analyzed for each wavelength of light corresponds to a preset black ice pattern,
Obtaining the object position and reflectance
Obtaining an object position and reflectance from the reflected light by emitting light in a predetermined range in which the plurality of lidars overlap each other in part,
The step of determining whether the black ice is
The black ice detection method of detecting, as a black ice area, an area appearing as a black ice pattern in which the magnitudes of reflectance of at least two or more of the plurality of lidars are reversed from each other in an area where the plurality of lidars overlap and detect.
delete delete The method of claim 7, wherein the normalizing step
Black ice detection method for normalizing the reflectance of light for each wavelength on a dry road surface to be the same reference reflectance. The method of claim 7, wherein the plurality of lidar
A black ice detection method that emits light of a specified wavelength in each of the NIR (Near InfraRed) range and MIR (Middle InfraRed) range, or emits light of different wavelengths in the NIR range. The method of claim 7, wherein the black ice detection method
The black ice detection method further comprising notifying a vehicle driver of the detected black ice area in a visual or auditory manner when the black ice area is detected.

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