KR20190019753A - Method and apparatus for determining factors of fault in satelite - Google Patents

Abstract

Disclosed is a method for determining a cause of a failure in a satellite. The method comprises the following steps: selecting a satellite to be tested; selecting two surrounding satellites included in a surrounding satellite group for detecting whether a satellite to be tested has a failure; determining whether the satellite to be tested has the failure using information of the satellite to be tested and information of two surrounding satellites; analyzing changing trend of test statistic calculated from the information of the satellite to be tested and information of the surrounding satellite group If it is determined that the satellite to be tested has the failure; and determining the cause of the failure of the satellite to be tested based on an analysis result.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for determining a cause of a failure of a satellite,

The present disclosure provides an apparatus and method for determining the cause of failure of a satellite.

A satellite navigation system is a system that calculates the position of a user through trilateration using the knowledge of the position of four or more satellites and users and the distance between them. The position of the user can not be calculated accurately if there is a large error or a problem in the satellite position or distance measurement. Therefore, satellite navigation system is applied to monitor satellite position and distance measurement.

In general, a number of terrestrial reference stations are used to monitor the status of satellite orbits and satellite clocks. Considering the geometric concept of DOP (Dilution of Precision), which is mainly used in the satellite navigation system, the range of the ground reference station is important because it is advantageous to measure the position of the satellite as the distribution of the ground reference station becomes farther away. However, due to the limitations of the size of the earth, land - based stations can not be distributed widely enough. Furthermore, ground - based stations are required to be installed on the ground, Therefore, the measurement of the distance from the ground reference station to the satellite obtained from the ground reference station is inaccurate.

Also, in the satellite navigation system, an error occurs due to the difference between the satellite orbit calculated by the broadcasting ephemeris and the position where the actual satellite is located, so that the status of the satellite orbit is monitored. In addition, in the satellite navigation system, the atomic clock is used as the satellite 's view, and the abnormal state of the atomic clock may occur due to various factors. On the other hand, general satellite orbit and satellite watch status monitoring is performed by measuring the distance from the ground reference station to the satellite. In this case, the measured distance value may have errors due to various factors, such as ionospheric delay, convective layer delay, elevation angle error. Therefore, it is necessary to remove the above errors in order to monitor the status of satellite orbit and satellite clock. When eliminating the error, the methods using the dual frequency method and the error model are mainly used, but the above methods can not eliminate all of the above errors. In particular, measurements from low elevation satellites are inaccurate because the noise is large.

Therefore, in order to detect the failure of the satellite, the position of the satellite must be determined in a more accurate manner. In addition, since the resolution method of the cause of the failure of the satellite is different, it is important to accurately grasp the cause of the failure of the satellite.

And an apparatus and method for determining the cause of the failure of the satellite. The technical problem to be solved by this embodiment is not limited to the above-mentioned technical problems, and other technical problems can be deduced from the following embodiments.

As a technical means for achieving the above technical object, a first aspect of the present disclosure provides a method for controlling a satellite, comprising: selecting a satellite to be inspected; Selecting two surrounding satellites included in a peripheral satellite group for detecting the failure of the satellite to be inspected; Determining whether the satellite to be inspected is faulty using information of the satellite to be inspected and information of the two surrounding satellites; Analyzing a change trend of a test statistic calculated from information of the satellite to be surveyed and information of the peripheral satellite group when it is determined that the satellite to be tested is broken; And determining a cause of the failure of the satellite to be inspected based on the analysis result.

Forming a plurality of triangles having one vertex of the satellite to be inspected and the remaining vertices of two neighboring satellites included in the neighboring satellite group as the remaining vertices; Obtaining a measurement of a distance between two surrounding satellites constituting each of the plurality of triangles, and calculating an estimate; Calculating a test statistic for a distance between two adjacent satellites constituting each of the plurality of triangles by using the difference between the obtained measured value and the calculated estimated value; And analyzing a change trend of the calculated test statistic for each of the plurality of triangles.

If the trends of the change of the test statistic for each of the plurality of triangles are all the same, the cause of the failure of the test target satellite is determined as a satellite clock failure, and the test statistic for each of the plurality of triangles When the direction of the change trend is only partially the same, the cause of the failure of the satellite to be inspected can be determined as a satellite orbit failure.

Forming a triangle having one vertex of the satellite to be inspected and the other vertices of the two surrounding satellites included in the peripheral satellite group as the remaining vertices; Obtaining a measurement of the distance between the two surrounding satellites constituting the triangle, and calculating an estimate; Calculating a test statistic for the distance between the two nearby satellites using the obtained measurements and the difference of the calculated estimates; And comparing the calculated test statistic with a threshold value to determine whether or not the test target satellite is faulty.

(여기서,

는 검정통계량의 평균,

는 임계값의 조정변수,

는 검정통계량의 표준편차를 나타낸다)에 의해 산출되는 것일 수 있다.Further, the threshold value may be expressed by Equation

(here,

Is the mean of the test statistic,

Is the adjustment variable of the threshold value,

Is the standard deviation of the test statistic).

(여기서,

및

는 주변 위성들에 대한 검사대상 위성의 방위각을 나타낸다)을 이용하여 결정되는 것일 수 있다.The sensitivity, which indicates the performance of the test statistic,

(here,

And

Represents the azimuth angle of the target satellite with respect to the surrounding satellites).

The estimation value may be calculated by calculating the subtended angle of the inspection target satellite determined by the two surrounding satellites and applying the subtended angle to the trigonometric law.

According to a second aspect of the present disclosure, there is provided a satellite-to-be-monitored system for selecting a satellite to be inspected, selecting a group of surrounding satellites for detecting the failure of the satellite to be inspected, Wherein the control unit determines whether or not the satellite to be inspected is faulty and analyzes the change trend of the test statistic calculated from the information of the satellite to be surveyed and the information of the surrounding satellite group when the satellite to be tested is determined to be broken, And a controller for determining a cause of the failure of the satellite to be inspected based on the determination result.

The third aspect of the present disclosure can provide a computer-readable recording medium on which a program for causing a computer to execute the method of the first aspect is recorded.

FIGS. 1A and 1B are diagrams illustrating exemplary triangular geometric and physical parameters of a plurality of satellites according to an embodiment.
2 is a diagram illustrating an example of a histogram and a standard normal distribution of a test statistic according to an embodiment.
3A and 3B are diagrams illustrating an example of the physical parameters used to calculate the sensitivity of a test statistic according to one embodiment.
4A to 4C are views for explaining a sensitivity measurement result according to an embodiment.
5 is a diagram for explaining a range in which a failure of a satellite can be detected according to an embodiment.
5 is a diagram illustrating an example of processing correction information in a central processing device and a user device according to one embodiment.
6 is a flowchart of a method for determining a cause of a failure of an inspection target satellite according to an embodiment.
7 is a flowchart of a method for analyzing a change trend of a test statistic according to an embodiment.
8A and 8B are diagrams illustrating an example of a satellite failure cause according to an embodiment.
FIG. 9 is a diagram for explaining an example of a change in a test statistic according to a cause of a satellite failure according to an embodiment.
10 is a block diagram of a satellite fault cause determination device according to one embodiment.

The phrases " in some embodiments " or " in one embodiment " appearing in various places in this specification are not necessarily all referring to the same embodiment.

Some embodiments of the present disclosure may be represented by functional block configurations and various processing steps. Some or all of these functional blocks may be implemented with various numbers of hardware and / or software configurations that perform particular functions. For example, the functional blocks of the present disclosure may be implemented by one or more microprocessors, or by circuit configurations for a given function. Also, for example, the functional blocks of the present disclosure may be implemented in various programming or scripting languages. The functional blocks may be implemented with algorithms running on one or more processors. In addition, the present disclosure may employ conventional techniques for electronic configuration, signal processing, and / or data processing, and the like. Terms such as " mechanism, " " element, " " means, " and " configuration " and the like are widely used and are not limited to mechanical and physical configurations. In addition, the term " "... Module " or the like means a unit for processing at least one function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

Also, the connection lines or connection members between the components shown in the figures are merely illustrative of functional connections and / or physical or circuit connections. In practical devices, connections between components can be represented by various functional connections, physical connections, or circuit connections that can be replaced or added.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1A and 1B are diagrams illustrating exemplary triangular geometric and physical parameters of a plurality of satellites according to an embodiment.

는 ISL(inter-satellite links)을 이용하여 산출되는 값이며, ISL을 이용하여 산출된 값은 우주공간상에서 신호의 송수신이 이뤄지므로 이온층, 대류층, 다중 경로에는 영향을 받지 않는다. Referring to Figs. 1A and 1B,

Is calculated using inter-satellite links (ISL), and the values calculated using ISL are not affected by ionosphere, convection, and multipath because signals are transmitted and received in space.

는 방송궤도력 정보를 이용하여 산출되는 값이다. 또한, 삼각형 각 꼭지점의 각도

는, 방송궤도력 정보를 이용한 위성 좌표(

)를 내적하여 산출될 수 있다.Also,

Is a value calculated using broadcast ephemeris information. Further, the angle of each triangle corner point

Satellite coordinates using the broadcasting ephemeris information (

) Can be calculated internally.

와, 아래 수학식 1 또는 수학식 2를 통해 산출된 두 주변 위성(20, 30) 간의 거리에 대한 추정치인

의 차이가 매우 작다.Since both the satellite 10 to be inspected and the two surrounding satellites 20 and 30 constituting the triangle in FIG. 1A are in a normal state, a measurement value of the distance between two adjacent satellites 20 and 30 obtained using the ISL

And an estimated value of the distance between two adjacent satellites 20 and 30 calculated by the following equation (1) or (2)

Is very small.

On the other hand, FIG. 1B is a view for explaining an example of a case where a failure occurs in a satellite to be inspected constituting a triangle in FIG. 1B. The position 11a in the case where the satellite to be inspected is in the normal state and the position 11b in the case where the failure occurs may be different.

In one embodiment, a triangle may be formed with one vertex of the satellite to be inspected and the remaining vertices of two adjacent satellites included in the neighboring satellite group. Further, it is also possible to obtain the measured values of the distances between the target satellites constituting the triangle and the two surrounding satellites 21 and 31, and to calculate the estimated value.

와, 위 수학식 1 또는 수학식 2를 통해 산출된 두 주변 위성(21, 31) 간의 거리에 대한 추정치

의 차이가 발생할 수 있다.For example, when a failure occurs in the satellite to be inspected, a measurement of the distance between two adjacent satellites 20 and 30 obtained using the ISL

And an estimated value of the distance between two adjacent satellites 21 and 31 calculated through the above equation (1) or (2)

May occur.

와 추정치

의 차이를 이용하여 검정통계량을 산출할 수 있으며, 산출된 검정통계량과 임계값을 비교함으로써 검사대상 위성의 고장여부를 결정할 수 있다. 이에 대해서는 도 2에서 자세히 설명하기로 한다.On the other hand,

And estimate

The test statistic can be calculated using the difference between the test statistic and the threshold, and the failure of the test target satellite can be determined by comparing the calculated test statistic with the threshold value. This will be described in detail with reference to FIG.

2 is a diagram illustrating an example of a histogram and a standard normal distribution of a test statistic according to an embodiment.

와 추정치

의 차이를 이용하여 검정통계량을 산출할 수 있다. 검정통계량

는 아래 수학식 3으로 표현될 수 있다.As described above with reference to FIG. 1, a measurement of the distance between two adjacent satellites

And estimate

Can be used to calculate the test statistic. Test statistic

Can be expressed by the following equation (3).

The size of the test statistic can be large if the satellite to be tested is out of order compared to when the satellite under test is in a normal state.

The failure of the target satellite can be determined by comparing the test statistic calculated through Equation (3) with the threshold value.

Referring to FIG. 2, a test statistic 210 and a standard normal distribution 220 are shown. The test statistic 210 may not follow the standard normal distribution 220 and both tail sides may deviate from the standard normal distribution 220. This phenomenon is referred to as Sigma Inflation phenomenon. It can compensate for the occurrence of Sigma Inflation phenomenon and can calculate the threshold value by using the overbidden distribution.

을 임계값과 비교하여 검사대상 위성의 고장여부를 결정할 수 있다. 일 실시예에서 정상상태일 때의 검정통계량

는 아래 수학식 4와 같이 영평균, 가우시안 분포를 갖는다.The test statistic of equation (3)

Is compared with the threshold value, it is possible to determine whether the satellite to be inspected is faulty or not. In one embodiment, the test statistic at steady state

Has a zero mean and Gaussian distribution as shown in Equation (4) below.

는 검정통계량의 평균,

는 검정통계량의 표준편차이며,

는 임계값의 조정변수로서 3-sigma를 기준으로 산출된 값이다.Finally, the threshold value can be expressed by the following equation (5). In Equation (5)

Is the mean of the test statistic,

Is the standard deviation of the test statistic,

Is a value calculated based on 3-sigma as an adjustment parameter of the threshold value.

가 임계값

보다 큰 경우 검사대상 위성이 고장난 것으로 결정할 수 있다.In one embodiment, the test statistic

Lt; / RTI >

It can be determined that the satellite to be inspected has failed.

On the other hand, the steady-state data for the statistical analysis used in the threshold calculation may be the weekly matching data from February 13th to 19th, 2011. The data used in the RINEX file provided by the Geographical Information Service can be used as the reference country. GPS can also be used for analysis. On the other hand, the ISL measurement can be used as the ISL measurement, considering the final product provided by the IGS as the actual position of the satellite and the distance value based on this position. Since the IGS is provided on a 15-minute basis, satellite coordinates can be calculated using broadcast ephemeris to match this period. The IGS can also be used as the actual position value of the satellite. To use many samples, all satellites visible at the source station at each time point are available. The above procedure can be performed for all three triangles that can be configured as visible satellites, and one satellite for each satellite in a triangle.

3A and 3B are diagrams illustrating an example of the physical parameters used to calculate the sensitivity of a test statistic according to one embodiment.

Referring to FIGS. 3A and 3B, a target satellite 310 and two surrounding satellites 320 and 330 are shown.

)가 발생한다. 단위 벡터 차이(

)는 아래 수학식 6으로 표현될 수 있다.On the other hand, due to the orbital force failure of the satellite 310 to be inspected,

). Unit vector difference (

Can be expressed by Equation (6) below.

In addition, the unit vectors shown in FIG. 3A can be expressed by Equation (7) below.

If the test statistic is derived using Equations (6) and (7), the following Equation (8) can be derived.

를 제외한 나머지는 고정 값이다. 검정통계량은 에 의해 결정될 수 있다.On the other hand, when the local coordinate system is set as shown in FIG. 3B,

The rest are fixed values. The test statistic is Lt; / RTI >

및

는 주변 위성들(320, 330) 각각에 대한 검사대상 위성(310)의 방위각일 수 있다.Referring to FIG. 3B, the unit vector can be expressed by Equation (9) below. In Equation (9)

And

May be an azimuth angle of the target satellite 310 with respect to each of the nearby satellites 320 and 330.

는 최종적으로 아래 수학식 10과 같이 표현될 수 있다.Also, depending on the coordinate system setting

Can be finally expressed as the following Equation (10).

The sensitivity of the test statistic can be determined using Equation (10). The sensitivity of the test statistic may have different sensitivities depending on the arrangement of the test target satellite 310 and the two nearby satellites 320 and 330.

4A to 4C are views for explaining a sensitivity measurement result according to an embodiment.

Referring to FIG. 4A, there is shown a sensitivity measurement result of a method using a ground-based augmentation system (GBAS) and a method using a ground measurement between two antennas.

Referring to FIG. 4B, the sensitivity measurement result of the method using two reference stations on the ground instead of the two surrounding satellites in the triangle method described in FIG. 1 is shown.

Referring to FIG. 4C, the results of the sensitivity measurement according to the method of FIGS. 1 to 3 are shown.

Referring to FIGS. 4A to 4C, it can be seen that the sensitivity measurement result of FIG. 4C is the largest. The larger the sensitivity, the smaller the detectable error, one of the performances of the fault detection technique, can be. Thus, the method according to Figs. 1 to 3 can have better fault detection performance than other methods.

5 is a diagram for explaining a range in which a failure of a satellite can be detected according to an embodiment.

Referring to FIG. 5, in order to simulate a range in which a failure of a satellite can be detected, a failure location of the satellite to be tested is set to 5 m for each coordinate axis. As a result of the simulation, when the failure of the target satellite is detected by using the two reference stations on the ground, it is possible to detect a failure of about several km, while the failure of the target satellite can be detected by the method of FIGS. A fault of several meters can be detected.

6 is a flowchart of a method for determining a cause of a failure of an inspection target satellite according to an embodiment.

Referring to FIG. 6, in step 610, a target satellite can be selected. In addition, in step 620, two nearby satellites included in the peripheral satellite group for detecting the failure of the target satellite can be selected.

In step 630, it is possible to determine whether the satellite to be inspected is faulty. In one embodiment, the information of the selected satellite to be inspected in step 610 and the failure of the target satellite can be determined using the two nearby satellites selected in step 620.

In one embodiment, the information of the satellite to be inspected and the information of the surrounding satellite group may include, but are not limited to, the major axis length of the elliptical orbits, the eccentricity, the direction of the perihelion, the passing point of the perihelion, the orbit inclination,

In one embodiment, the failure of the satellite to be inspected can be determined by applying the information of the satellite to be inspected and the information of the two surrounding satellites to the method of FIG. In order to determine whether the satellite to be inspected is faulty, a triangle may be formed in which one satellite is a vertex and the other two surrounding satellites included in the satellite are the remaining vertices. It is also possible to obtain a measure of the distance between two nearby satellites constituting the triangle and to calculate an estimate. In addition, a test statistic for the distance between two nearby satellites can be calculated using the obtained measurement value and the difference between the calculated estimates. Also, by comparing the calculated test statistic with the threshold value, it is possible to determine whether the satellite to be tested is faulty or not.

In one embodiment, measurements of the distance between satellites can be obtained from inter-satellite links (ISL). In addition, an estimate of the distance between satellites can be calculated using broadcast ephemerides. For example, the estimated value of the distance between satellites can be calculated by calculating the subtended angle of the target satellite determined by the two surrounding satellites, and applying the calculated subtracted angle to the trigonometric law.

If it is determined in step 630 that the target satellite does not fail, the status of the target satellite can be continuously monitored. On the other hand, if it is determined in step 630 that the satellite to be tested has failed, the process proceeds to step 640.

If it is determined in step 640 that the satellite to be tested has failed, the change trend of the test statistic calculated from the information of the satellite to be tested and the information of the surrounding satellite group can be analyzed.

In satellite navigation systems, satellite information can be provided in a variety of ways. For example, satellite information can be provided by the Almanac and Ephemeris methods, and both methods provide satellite information with the Kepler 6 parameters.

The details of analyzing the change trend of the test statistic calculated from the information of the satellite to be tested and the information of the surrounding satellite group will be described later with reference to FIG.

In step 650, the cause of the failure of the satellite to be inspected can be determined based on the analysis result. The cause of the satellite failure may include, but is not limited to, a satellite clock failure, a satellite orbital failure, and the like.

Details of determining the cause of the failure of the satellite to be inspected will be described later with reference to FIGS. 8 and 9. FIG.

7 is a flowchart of a method for analyzing a change trend of a test statistic according to an embodiment.

Referring to FIG. 7, in step 710, a plurality of triangles may be formed with one satellite as a vertex and the other two surrounding satellites included in the satellite as a remaining vertex. In one embodiment, the peripheral satellite group may include satellites distributed around the target satellite, but the distribution of the peripheral satellite group is not limited thereto.

In step 720, a measure of the distance between two nearby satellites constituting each of the plurality of triangles may be obtained and an estimate may be calculated. In one embodiment, the method of FIG. 1 may be used to obtain measurements and calculate an estimate.

The test statistic for the distance between two adjacent satellites constituting each of the plurality of triangles can be calculated using the difference between the measured value and the calculated estimated value obtained in step 730. In one embodiment, the method of Figure 1 may be used to calculate a test statistic for the distances between the satellites

In step 740, a change trend of the test statistic calculated for each of the plurality of triangles may be analyzed. In one embodiment, the change trends of the test statistic calculated according to the cause of the failure of the target satellite may be the same or different.

For example, the distance between satellites can be calculated using the difference between the time of the satellite with respect to the radio transmission time and the time of the receiver. The time of the satellite uses an atomic clock. Although the atomic clock is stable, an abnormal state may occur due to various factors, which may cause an error in the position calculation. If the cause of the failure of the satellite to be tested is a satellite clock failure, the same trend change can be detected in the test statistic calculated in step 740. For example, the calculated test statistics may all increase or decrease.

In addition, if the cause of the failure of the target satellite is a satellite orbital failure, the test statistic calculated in step 740 may change in different directions. The terrestrial reference station estimates the orbit of the satellite and transmits information about the estimated orbit of the satellite to the satellite and the satellite can broadcast this information to the user. An error may occur due to the difference between the satellite orbit calculated by the broadcasting ephemeris and the position where the actual satellite is located. If the cause of the failure of the satellite to be surveyed is a satellite orbit failure, a change in the trends different from each other can be detected in the test statistic calculated in step 740. For example, some of the calculated test statistic may be increased and some of the test statistic may be decreased.

8A and 8B are diagrams illustrating an example of a satellite failure cause according to an embodiment.

The change trend of the test statistic calculated from the information of the satellites 810 and 820 and the information of the surrounding satellites 811 to 815 and 821 to 825 when the satellites 810 and 820 to be inspected are broken, It is possible to determine the cause of failure of the satellites 810 and 820 to be inspected.

Referring to FIG. 8A, the distribution of satellites according to satellite orbital failure is shown. When a failure occurs in the trajectory of the satellite 810 to be inspected, the variation of the ISL measurement values varies according to the distribution of the nearby satellites 811 to 815, so that some of the calculated test statistic values are increased, Some can be reduced.

Referring to FIG. 8B, a distribution of satellites according to a satellite clock failure is shown. Regardless of the distribution of the surrounding satellites 821 to 825 of the satellite 820 to be inspected, the variation of the ISL measurement values all decrease or increase equally, so that the calculated test statistic values may all decrease or increase.

FIG. 9 is a diagram for explaining an example of a change in a test statistic according to a cause of a satellite failure according to an embodiment.

Referring to FIG. 9, in the case of satellite orbital failure, there may be no directionality in the trend of change of the test statistic. In one embodiment, some of the test statistics may increase and some of the test statistics may decrease.

On the other hand, in the case of satellite clock failure, there may be a certain direction in the change trend of the test statistic. In one embodiment, all of the test statistics can be reduced or increased.

If the satellite fails, the cause of the failure of the satellite must be determined in order to take appropriate measures. The cause of the failure of the satellite can be determined easily and quickly based on the result of the test statistic change as shown in FIG.

10 is a block diagram of a satellite fault cause determination device according to one embodiment.

Referring to FIG. 10, the satellite failure determination device 100 may include a control unit 110, a communication unit 120, and a memory 130. Only the components associated with the embodiment are shown in the device 100 shown in Fig. Therefore, it will be understood by those of ordinary skill in the art that other general-purpose components other than the components shown in FIG. 10 may be further included.

The control unit 110 can detect a failure of the satellite described in Figs. 1 to 9 and control a series of processes for determining the cause of failure of the satellite.

In one embodiment, a peripheral satellite group for detecting the failure of the satellite to be inspected by the controller 110 can be selected. In addition, the controller 110 can determine whether the target satellite is in failure by using the information of the satellite to be inspected and the information of the surrounding satellite group. Also, when it is determined that the satellite to be tested has failed, the controller 110 can analyze the change trend of the test statistic calculated from the information of the satellite to be tested and the information of the surrounding satellite group. Also, the controller 110 can determine the cause of the failure of the target satellite based on the analysis result.

In one embodiment, the communication unit 120 may receive information of the satellite to be inspected and the surrounding satellite group. For example, satellite information receiver can receive satellite information generated by Almanac and Ephemeris method.

In one embodiment, the memory 130 may store a satellite fault detection method and a satellite fault cause determination method.

On the other hand, the control unit 110 of the satellite failure determining device 100 may be manufactured in at least one hardware chip form and mounted on the determination device 100 as a satellite failure cause. For example, the control unit 110 may detect the failure of the satellite and may be fabricated in the form of a dedicated hardware chip for determining the cause of the failure of the satellite, or a conventional general purpose processor (e.g., a CPU or an application processor) May be fabricated as part of a dedicated processor (e.g., a GPU) and loaded into the central processing device 10 described above.

The embodiments may also be embodied in the form of a recording medium including instructions executable by a computer, such as program modules, being executed by a computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium may include both computer storage media and communication 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. Communication media typically comprise any information delivery media, including computer readable instructions, data structures, other data of a modulated data signal such as program modules, or other transport mechanisms.

Also, in this specification, the term " part " may be a hardware component such as a processor or a circuit, and / or a software component executed by a hardware component such as a processor.

It will be understood by those skilled in the art that the foregoing description of the specification is for illustrative purposes only and that those skilled in the art will readily understand that various changes in form and details may be made therein without departing from the spirit and scope of the invention. It will be possible. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as including the claims.

Claims (10)

A method for determining a cause of a failure of a satellite,
Selecting a satellite to be inspected;
Selecting two surrounding satellites included in a peripheral satellite group for detecting the failure of the satellite to be inspected;
Determining whether the satellite to be tested is faulty using the information of the selected satellite to be inspected and the information of the two selected nearby satellites;
Analyzing a change trend of a test statistic calculated from information of the satellite to be surveyed and information of the peripheral satellite group when it is determined that the satellite to be tested is broken;
Determining a cause of the failure of the target satellite based on the analysis result;
/ RTI > The method according to claim 1,
The step of analyzing the change trend of the test statistic may include:
Forming a plurality of triangles having the vertex of the inspection target satellite as one vertex and the vertices of the two surrounding nearby satellites included in the peripheral satellite group as the rest vertices;
Obtaining a measurement of a distance between two surrounding satellites constituting each of the plurality of triangles, and calculating an estimate;
Calculating a test statistic for a distance between two adjacent satellites constituting each of the plurality of triangles by using the difference between the obtained measured value and the calculated estimated value; And
Analyzing a change trend of the calculated test statistic for each of the plurality of triangles;
/ RTI > 3. The method of claim 2,
Wherein the step of determining the cause of the failure of the target satellite comprises:
Determining a cause of the failure of the satellite to be tested as a satellite clock failure when the trends of the change of the test statistic for each of the plurality of triangles are all the same,
Wherein if the directions of change in the test statistic for each of the plurality of triangles are only partially identical, the cause of the failure of the target satellite is determined as a satellite orbit failure. The method according to claim 1,
Wherein the step of determining whether the satellite to be inspected is faulty comprises:
Forming a triangle having one vertex of the satellite to be inspected and the other vertices of the two surrounding satellites;
Obtaining a measurement of the distance between the two surrounding satellites constituting the triangle, and calculating an estimate;
Calculating a test statistic for the distance between the two nearby satellites using the obtained measurements and the difference of the calculated estimates; And
Determining whether the satellite to be tested is faulty by comparing the calculated test statistic with a threshold value;
≪ / RTI > 3. The method of claim 2,
Wherein the measurements are obtained from inter-satellite links (ISL), and the estimates are calculated using broadcast ephemeris. 5. The method of claim 4,
The threshold value may be expressed by Equation

(here,

Is the mean of the test statistic,

Is the adjustment variable of the threshold value,

Is the standard deviation of the test statistic). The method according to claim 1,
The sensitivity, which indicates the performance of the test statistic,

(here,

And

Is an azimuth angle of the satellite to be inspected relative to nearby satellites. 6. The method of claim 5,
The estimator may further comprise:
Calculating a subtended angle of the satellite to be inspected determined by the two surrounding satellites, and applying the subtended angle to the trigonometric law. A device for determining a cause of a fault in a satellite,
The target satellite is selected,
A group of nearby satellites for detecting the failure of the target satellite,
Determining whether the satellite to be inspected is faulty using the information of the satellite to be inspected and the information of the surrounding satellite group,
Analyzing the change trend of the test statistic calculated from the information of the satellite to be surveyed and the information of the peripheral satellite group when it is determined that the test target satellite has failed,
A controller for determining a cause of the failure of the target satellite based on the analysis result;
. A computer-readable recording medium having recorded thereon a program for causing a computer to execute the method according to any one of claims 1 to 8.

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