KR20180061823A - System and Method for Estimating Road condition using GPS Signal - Google Patents

Abstract

Provided are a method and system for notifying a road user of a real-time detection result by dividing a road state into ice, snow, wet, dry, and the like using reflectivity of a GPS microwave signal and a refractive index of a material. The present invention can prevent human loss and property loss due to traffic accidents by predicting and predicting major causes of winter traffic accidents such as black ice. In addition, the present invention can be used as weather observation information by detecting a snowy area and more accurately detecting a sea ice point by dividing the road state into snow, ice, and water.

Description

Technical Field [0001] The present invention relates to a method and system for estimating a ground state using a GPS signal,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present disclosure relates to a method and system for estimating a ground state, and more particularly, to a technique for estimating a road state using a GPS signal.

Unless otherwise indicated herein, the contents set forth in this section are not prior art to the claims of this application and are not to be construed as prior art to be included in this section.

The 'black ice' phenomenon, which occurs every winter, creates an invisible ice road on the road, causing a very dangerous traffic accident. Black ice is a phenomenon in which transparent ice covers over asphalt as if it were coated, and the driver's eyes appear dry without ice on the road. The rain falls from the image temperature, but when the surface temperature falls below zero and the surface temperature of the road falls below zero, it freezes on the floor as it rains. Black ice occurs frequently on shady roads at dawn or in the morning with low temperatures in the winter, and is often seen in a way similar to or slightly wetted by road colors, causing many drivers to make mistakes. Recently, the National Police Agency has investigated 706 traffic accidents in the past five years, out of 7,236 deaths. Among the 892 deaths, 706 people died from black ice (NewSis, Dec. 11, 2014).

1. Korean Patent Publication No. 10-2014-0169747 (December 1, 2014) 2. Korean Patent Publication No. 10-2014-0009744 (Apr. 21, 2014)

Real-time detection results are obtained by dividing the road state into ice, snow, wet, dry, and the like using the reflectivity of the GPS microwave signal and the refractive index of the material. A method and system for informing users is provided.

The ground state estimating apparatus using the GPS signal according to the embodiment includes GPS observation information including GPS signals and right hand circular polarization (RHCP) and left hand circular polarization (LHCP) observed at a target observation point, A satellite data collection module for receiving a signal; A GPS signal processing module for processing a GPS signal and a reflection signal for each GPS polarized light to calculate a normalized polarization reflection index (NPRI), which is a normalized polarized reflection signal; And a ground state determination module for comparing the calculated NPRI with the previously stored reference NPRI and determining the ground state as ice, snow, wet, or dry according to the comparison result; .

(A) a satellite data collection module for collecting satellite observation information including a GPS signal and a right hand circular polarization (RHCP), a left hand circular Receiving a reflection signal by GPS polarized light including a polarization; (B) calculating a normalized polarization reflection index (NPRI), which is a normalized polarized reflection signal, by processing a GPS signal and a reflection signal for each GPS polarized light in a GPS signal processing module; And (C) comparing the calculated NPRI with the previously stored reference NPRI and determining the ground state as ice, snow, wet or dry according to the comparison result; .

Through this disclosure, it is possible to prevent loss of lives and property loss caused by traffic accidents by predicting and predicting black ice, which is the main cause of traffic accidents in winter, Also, by dividing the ground state into snow, ice, water, etc., it is possible to detect the snowy area and to detect the sea ice point more precisely and use it as weather observation information.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a block diagram showing a configuration of a ground state estimating apparatus using GPS signals according to an embodiment
2 is a block diagram of a satellite data collection module 110 according to an embodiment.
3 is a block diagram of the GPS signal processing module 130 according to the embodiment.
FIG. 4 is a graph showing the index of refraction index
5 is a flowchart illustrating a ground state estimation method using a GPS signal according to an embodiment.
6 is a flowchart for explaining a detailed process of the signal processing step S120 according to the embodiment
7A is a graph showing NPRI calculated theoretically for each of water, ice, snow, and soil according to the embodiment by the incidence angle of the GPS signal
FIG. 7B is a graph showing the results of measurement of NPRI by soil condition using GPS signals according to the embodiment
FIG. 7c is a graph showing the NPRI values obtained by using GPS signals in the process of spraying water on the asphalt road and changing the state with ice
8 is a software implementation example of a ground state determination system using a GPS signal according to an embodiment

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like numbers refer to like elements throughout.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

     1 is a block diagram showing the configuration of a ground state estimating apparatus using a GPS signal according to an embodiment.

     Referring to FIG. 1, the ground state estimating apparatus may include a satellite data collecting module 110, a GPS signal processing module 130, and a ground state determining module 150. In addition, the ground state estimation system using the GPS signal according to the embodiment may include a satellite data collection device for collecting GPS signals and a signal processing device for processing collected GPS signals.

The term " module " as used herein should be interpreted to include software, hardware, or a combination thereof, depending on the context in which it is used. For example, the software may be machine language, firmware, embedded code, and application software. As another example, the hardware may be a circuit, a processor, a computer, an integrated circuit, an integrated circuit core, a sensor, a micro-electro-mechanical system (MEMS), a passive device, or a combination thereof.

The satellite data collection module 110 receives and collects satellite observation information including GPS signals.

The GPS signal processing module 130 processes the GPS polarized reflection signal to calculate a Normalized Polarization Reflectance Index (NPRI). According to an embodiment, the GPS polarized reflection signal includes Right Hand Circular Polarization (RHCP) and Left Hand Circular Polarization (LHCP) observed at the object observation point. RHCP and LHCP are various reflection signals of GPS signals and are polarization signals that periodically rotate within a cross section perpendicular to the traveling direction of the electromagnetic wave radiated from the antenna. If we combine horizontal and vertical polarizations with the same size and phase difference of 90 degrees, the resultant circular vector will form a circle, so that when it rotates clockwise, it will be Right Hand Circular Polarization, Left Hand Circular Polarization). In the embodiment, RHCP and LHCP are various polarized signals including a right-handed circularly polarized wave and a left-handed circularly polarized wave which are transmitted while the polarization plane changes horizontally, vertically and horizontally into a spiral shape like time and distance. Specifically, the RHCP and the LHCP are designed so that the oscillation direction of the electric displacement vector (or the magnetic field displacement vector) of the light wave is circularly polarized in the cross section perpendicular to the traveling direction of the electromagnetic wave radiated from the antenna, A rotating circular polarized signal, and a circular polarized signal in which the deflecting surface of the linear polarized light rotates at a constant angular velocity about the traveling direction of the light.

The ground state determination module 150 compares the NPRI, which is the normalized polarized reflection signal calculated by the reflection signal of the GPS signal, with the previously stored reference NPRI, and compares the ground state with ice, snow, (Wet), dry (dry) state, and the like. The ground state determination module 150 extracts the reference NPRI according to the ground state using the material-specific refractive index shown in FIG. 4, and compares the extracted NPRI with the extracted NPRI through the real-time GPS satellite reflectivity observation value And the ground state can be determined based on the comparison result.

FIG. 2 is a diagram illustrating a configuration of a satellite data collection module 110 according to an embodiment.

2, the satellite data collection module 110 according to the embodiment includes a hardware platform 131 (see FIG. 1) in which polarized signals (reflected signals) and GPS signals (direct signals) such as RHCP and LHCP receiving reflected polarized signals are input. And a signal processing unit 133. [0031] In the ground state determination system using the GPS signal according to the embodiment, the satellite data collection module can be implemented as a satellite data collection device. As shown in FIG. 2, the satellite data collecting apparatus 110 may include a reflected signal collecting unit 111 and a signal collecting unit 113.

In the embodiment, the signal collecting unit 113 collects a GPS signal (directed signal). Global Positioning System (GPS) is a global satellite navigation system that is used around the world for various purposes such as weapon guidance, navigation, surveying, cartography, geodesy, and time synchronization. In the GPS, the GPS receiver receives the microwave from several satellites traveling at about 20,1832 km and determines the position vector of the receiver. Each GPS satellite passes a point on the ground once a day and the GPS orbit is arranged to observe at least six GPS satellites on the ground. The GPS receiver processes the received signal using an antenna tuned to the frequency transmitted from the GPS satellite, a crystal oscillator, etc., calculates the coordinates and velocity vector of the receiver position in the signal processing unit, and outputs the calculated result. In the embodiment, the GPS signal observed by the GPS receiver receiving the GPS signal including the microwave is processed as input information, so that the ground state can be distinguished by water, ice, iced state, or the like.

A reflected signal collection unit 111 collects the polarized reflection signal of the GPS signal. The polarized reflection signal may include Right Hand Circular Polarization (RHCP) and Left Hand Circular Polarization (LHCP) observed at the object observation point. RHCP and LHCP are polarized signals that periodically rotate within a cross section orthogonal to the traveling direction of electromagnetic waves radiated from the antenna as various reflection signals of the GPS signal. RHCP is a right-handed circularly polarized signal rotating clockwise, and LHCP is a left-handed circularly polarized signal rotating counterclockwise. 3 is a block diagram of the GPS signal processing module 130 according to the embodiment.

3, the GPS signal processing module 130 includes a SNR (Signal to Noise Ratio) conversion unit 131, a reflectivity calculation unit 133, and a NPRI (Normalized Polarization Reflectance Index) calculation unit 135 .

The SNR converter 131 converts the carrier to a SNR (Carrier to Noise Density), which is a noise ratio, using the GPS signal received from the satellite data collecting unit using Equation 1 below.

(Equation 1)

,

)를 각각 산출한다.The reflectivity calculator 133 then calculates the SNR converted by the SNR converter using the left hand circular polarization (LHCP) and right hand circular polarization (RHCP)

,

Respectively.

(Equation 2)

(for LHCP)

(for LHCP)

(Equation 3)

(for RHCP)

(for RHCP)

The NPRI calculation unit 135 calculates an NPRI (Normalized Polarization Reflectance Index), which is an index representing the ground surface reflectivity relationship of the polarized light using the GPS satellite calculated through the equation (4).

(Equation 4)

In the present disclosure, the NPRI calculated using the GPS signal is compared with the NPRI according to the stored ground state, and the ground state can be determined by water, ice, drying, wetting, etc. according to the comparison result.

Hereinafter, a ground state determination method using GPS signals will be described in turn. Since the function (function) of the ground state determination method is essentially the same as that of the data display apparatus and the system, a description overlapping with those of FIGS. 1 to 4 will be omitted.

5 is a flowchart illustrating a ground state estimation method using a GPS signal according to an embodiment.

In step S110, the satellite data collection module 110 receives the satellite observation information including the microwave of the GPS signal. Thereafter, in step S120, the GPS signal processing module 130 processes the reflection signal for each GPS polarized light including RHCP (Right Hand Circular Polarization) and LHCP (LHCP) observed at a target observation point and outputs a Normalized Polarization Reflectance In step S130, the calculated NPRI is compared with the previously stored reference NPRI, and the ground state is classified into ice, snow, wet, dry, and the like according to the comparison result. .

6 is a flowchart illustrating a detailed process of the signal processing step S120 according to the embodiment.

In step S121, the SNR converting unit 131 converts the GPS signal into an SNR signal.

The GPS receiver receives Carrier to Noise Density (C / No), and C / No is defined by Equation 1.

(Equation 1)

Here, the SNR means a signal to noise ratio and the bandwidth means an observed microwave band width. The unit of C / No is dB (decibel).

In step S123, the reflectivity calculating unit 133 calculates the RHCP and the LHCP polarized SNR.

Equation 2 and Equation 3 show SNR information for RHCP and LHCP of the GPS signal observed in FIG.

(Equation 2)

(for LHCP)

(for LHCP)

(Equation 3)

(for RHCP)

(for RHCP)

When the GPS receiver observes the RHCP and the LHCP polarized light, the respective SNRs are calculated. In step S125, the NPRI calculating unit 135 calculates the normalized polarized reflectance ratio.

Equation 4 defines the polarization reflectance ratio in this disclosure. In the present disclosure, Equation 4 is defined as Normalized Polarization Reflectance Index (NPRI).

(Equation 4)

과

은 수식 2 와 수식 3에서 관측된 편광 별 반사도 이다. 본 개시에서 제안하는 NPRI를 사용함으로써 수식 2와 수식 3에 나타나는 안테나 별 특성정보 없이도, SNR 비율을 반사도 비율로 전환 할 수 있다. 또한 수식 4 에 의해 산출되는 NPRI 값은 입사각이 0도에서 90도로 변하는 동안 -1에서 1사이의 값으로 변환된다. 이 때문에 수식 4를 이용하여 반사율 데이터를 NPRI 값으로 정규화 할 수 있다. here

and

Is the reflectance per polarization observed in Eqs. (2) and (3). By using the NPRI proposed in the present disclosure, the SNR ratio can be converted to the reflectivity ratio without the antenna-specific characteristic information shown in Equation 2 and Equation 3. Also, the NPRI value calculated by the equation (4) is converted to a value between -1 and 1 while the incident angle varies from 0 to 90 degrees. Therefore, the reflectance data can be normalized to the NPRI value using Equation 4.

In step S130, the ground state determination module compares the stored standard NPRI with the calculated NPRI to determine the ground state. The standard NPRI is the data that the NPRI condition table is theoretically calculated and stored in advance for each water, ice, snow, and soil (Soil) as shown in FIG. In the embodiment, when the GPS signal is received, the stored standard NPRI value is compared with the NPRI value calculated through the GPS signal, and the road surface state is determined as the material state corresponding to the most similar NPRI value as the comparison result. The standard NPRI can be viewed as reference data for ground state determination.

FIGS. 7A to 7C are graphs showing standard NPRI graphs of standard and soil, and NPRI changes according to ground and water conditions. FIG.

7A is a graph showing NPRI calculated theoretically for water, ice, snow, and soil, respectively, according to the GPS signal incident angle according to the embodiment. As shown in FIG. 7A, it can be seen that NPRI exhibits different values depending on the GPS signal incident angle for each ground state.

FIG. 7B shows the result of measuring the NPRI according to the soil condition using the GPS signal according to the embodiment. The purple graph shown in FIG. 7B is the NPRI value of water according to the satellite incidence angle, and the blue graph is the NPRI graph of the dry soil. Referring to FIG. 7B, it can be seen that the NPRI graph according to the incidence angle is different in dry soil and wet soil condition. As shown in the left graph of FIG. 7B, it can be seen that the NPRI of the dried soil is close to the sky blue graph of the NPRI of the soil. The graph on the right side of FIG. 7B is a data obtained by observing the change of the GPS signal by spraying water on the soil. It can be seen that the GPS reflection signal observed in the watered soil represents the median value of the values in the purple and light blue graphs. This shows both the water and soil properties at the same time, and it can be seen from FIG. 7b that the soil condition can be determined through the NPRI numerical value.

 FIG. 7C is a graph showing the NPRI value obtained by using the GPS signal in a process in which water is sprayed on the asphalt road and the state changes to ice. The blue graph represents the NPRI for the water of the GPS satellites theoretically obtained and the sky blue graph represents the NPRI for the ice of the altitude of the GPS satellites. After the start of the experiment, the observed NPRI value changes, and it can be seen that the NPRI value changes according to the state of ice after 1 hour time elapses from the water state.

7A to 7C, the NPRI value obtained by normalizing the reflection signal of the GPS signal shows different values depending on the soil condition and the water condition, so that the drawing state and black ice can be detected using the NPRI value.

Through the present disclosure, real-time detection using the reflectivity of the GPS microwave signal and the refractive index of the material, which distinguishes road conditions as ice, snow, wet, dry, By informing road users in advance of the results, it is possible to prevent loss of life and property loss caused by traffic accidents by predicting and predicting main causes of winter traffic accidents such as black ice.

It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It is not limited to the embodiment.

110: satellite data acquisition module
130: GPS signal processing module
131: SNR converter
133: Reflectivity calculation unit
135: NPRI calculation unit
150: ground state determination module

Claims (6)

A ground state estimating apparatus using a GPS signal,
A satellite data collection module for receiving satellite observation information including a GPS signal and reflection signals for GPS polarized light including Right Hand Circular Polarization (RHCP) and Left Hand Circular Polarization (LHCP) observed at a target observation point;
A GPS signal processing module for processing a GPS signal and a reflection signal for each of the GPS polarized lights to calculate a normalized polarization reflection index (NPRI), which is a normalized polarized reflection signal; And
A ground state determination module that compares the calculated NPRI with the previously stored reference NPRI and determines the ground state as ice, snow, wet, or dry according to the comparison result; And a GPS receiver for receiving the GPS signal.
The GPS receiver according to claim 1, wherein the GPS signal processing module comprises:
The C / N (Carrier to Noise Density), which is the ratio of the carrier to the noise, is calculated using Equation 1

To SNR,
The transformed SNR is calculated using Equation 2

(for LHCP) and
Equation 3

(for RHCP) at a ratio of SNR

,

),
Equation 4

And a normalized polarization reflection index (NPRI), which is an index indicating a relation of ground surface reflectivity of each GPS polarized light calculated through the GPS signal, is calculated.
The method of claim 1, wherein the ground state determination module
The reference NPRI according to the ground state is extracted by using the refractive index of each material, the extracted NPRI is compared with the NPRI value extracted from the real time GPS satellite reflectance observation value, and the ground state is determined according to the comparison result A ground state estimating apparatus using GPS signals.
A method for estimating a ground state using a GPS signal,
(A) receiving satellite reflection information including GPS signals and right hand circular polarization (LHCP) and left hand circular polarization (LHCP) observed at a target observation point in a satellite data collection module ;
(B) processing a GPS signal and a reflection signal for each of the GPS polarized lights in a GPS signal processing module to calculate a normalized polarization reflection index (NPRI), which is a normalized polarized reflection signal; And
(C) comparing the calculated NPRI with the previously stored reference NPRI and determining the ground state as ice, snow, wet or dry according to the comparison result; And estimating the ground state using the GPS signal.
5. The method of claim 4, further comprising: (B) calculating the Normalized Polarization Reflectance Index (NPRI); The
(C / N), which is a noise ratio, from the GPS signal received from the satellite data collecting unit to Equation 1

To an SNR using the SNR;
The transformed SNR is calculated using Equation 2

(for LHCP) and
Equation 3

(for RHCP) at a ratio of SNR

,

); And
Equation 4

Calculating an NPRI (Normalized Polarization Reflectance Index), which is an index indicating a relation of ground surface reflectance of the polarized light using the GPS satellite calculated through the calculation; And estimating a ground state using the GPS signal.
5. The method of claim 4, further comprising: (C) determining the ground state as ice, snow, wet, or dry; The
The reference NPRI according to the ground state is extracted by using the refractive index of each material, the extracted NPRI is compared with the NPRI value extracted from the real time GPS satellite reflectance observation value, and the ground state is determined according to the comparison result Estimation of Ground Condition Using GPS Signal.

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