KR102144004B1 - Target Location Estimation Method for Distributed MIMO Radar using Ellipsoids Fitting - Google Patents

Abstract

A method of estimating a target position is disclosed. The target position estimation method includes (a) an ellipsoid with a bistatic range, which is a distance value from transmitters to receivers passing through a target, as a major axis, and a three-dimensional coordinate value of the transmitter and receiver as a focus. And (b) estimating the intersection of the modeled ellipsoids as the position of the target.

Description

Target Location Estimation Method for Distributed MIMO Radar using Ellipsoids Fitting}

The present invention relates to a method of estimating a target position, and more particularly, to a method of estimating a position of a target using an ellipsoid fitting technique in estimating a target position of a distributed MIMO radar.

Distributed MIMO (Multi-Input Multi-Output) radar system is a system in which omni-directional transceiver antennas are distributed with respect to the target. Due to the diversity of space obtained through distributed arrangement, the target detection and tracking performance can be improved. Much research is being conducted in the fields of military and civil affairs.

In particular, in relation to the research on estimating the position of the target, since the distributed MIMO radar system uses distributed omni-directional antennas, it is impossible to estimate the angle of arrival, so research using propagation delay time information instead.

In this regard, representative position estimation methods are the LS method of constructing a linear determinant using the difference in propagation delay time obtained from each transmitter, and estimating the position of the target through the linear least squares method, and inducing nonlinearity in propagation delay time information. There is a BRM technique that treats these terms as independent parameters to construct a linear determinant and estimates the position of a target through a linear least squares technique.

However, in the case of the above two techniques, the so-called ground antenna-based system in which the antennas have similar altitudes shows a problem that the altitude estimation performance of the target is significantly degraded. There is a problem that indicates failure in the process.

Korean Patent Registration KR 10-1615151 Korean Patent Registration KR 10-1150259

An object of the present invention is to provide a target position estimation method capable of accurately estimating the altitude of a target not only in a terrestrial antenna-based system, but also in a perfect terrestrial antenna-based system using an ellipsoid fitting technique, not the existing LS technique or BRM technique. have.

A method for estimating a target position according to an embodiment of the present invention includes (a) a bistatic range, which is a distance value from transmitters to receivers passing through a target, as a long axis, and the three-dimensional It may include modeling ellipsoids with a coordinate value as a focus, and (b) estimating an intersection point of the modeled ellipsoids as a position of the target.

According to an embodiment of the present invention, not only a terrestrial antenna based system but also a perfect terrestrial antenna based system may accurately estimate the altitude of a target.

1 illustrates a distributed MIMO radar system according to an embodiment of the present invention.
2 is a block diagram of a target position estimation apparatus according to an embodiment of the present invention.
3 shows modeled ellipsoids.
4 is a flowchart of a method for estimating a target position according to an embodiment of the present invention.
5A is a diagram illustrating a layout of transmitters and receivers to which a method for estimating a target position according to an embodiment of the present invention may be applied.
FIG. 5B shows the performance of each target position estimation method according to the standard deviation of altitude of the transmitter and receiver shown in FIG. 5A.

Specific structural or functional descriptions of embodiments according to the concept of the present invention disclosed in the present specification are exemplified only for the purpose of describing embodiments according to the concept of the present invention, and embodiments according to the concept of the present invention They may be implemented in various forms and are not limited to the embodiments described herein.

Since the embodiments according to the concept of the present invention can apply various changes and have various forms, the embodiments will be illustrated in the drawings and described in detail herein. However, this is not intended to limit the embodiments according to the concept of the present invention to specific disclosed forms, and includes changes, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first or second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are only for the purpose of distinguishing one component from other components, for example, without departing from the scope of the rights according to the concept of the present invention, the first component may be referred to as the second component, Similarly, the second component may also be referred to as a first component.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it is directly connected to or may be connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle. Expressions describing the relationship between components, for example, "between" and "just between" or "directly adjacent to" should be interpreted as well.

The terms used in the present specification are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprise" or "have" are intended to designate that the specified features, numbers, steps, actions, components, parts, or a combination thereof exist, but one or more other features or numbers, It is to be understood that the possibility of addition or presence of steps, actions, components, parts, or combinations thereof is not preliminarily excluded.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present specification. Does not. Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

1 illustrates a distributed MIMO radar system according to an embodiment of the present invention.

이고, 수신기들의 위치는

으로 나타내어질 수 있다.(여기서, m은 1, 2, ... , M이고, n은 1, 2, ... , N이다.)Referring to FIG. 1, a distributed multi-input multi-output (MIMO) radar system 1 according to an embodiment of the present invention includes M transmitters and N receivers (here, M and N is a natural number). In this case, each transmitter may refer to an antenna connected to the base station by wire or wireless, and each receiver may refer to an antenna connected to a terminal receiving signals from the base stations by wire or wireless. Meanwhile, the location of the transmitters on the 3D coordinates is

And the location of the receivers is

(Where m is 1, 2, ..., M, and n is 1, 2, ..., N.)

The antenna described in this specification may include an omni-directional antenna capable of transmitting a transmission signal even toward a terminal other than a target terminal.

A base station including a plurality of antennas manages a cell, which is a geographic area in which a communication service is provided, and supports wireless communication to a terminal in the cell. The base station performs a baseband signal processing function and can perform a radio resource allocation function for transmission and reception with a terminal in a cell.

On the other hand, the base station is an advanced base station (ABS), a high reliability base station (HR-BS), a node B (node B), an advanced node B (evolved node B, eNodeB), an access point ( access point, AP), radio access station (RAS), base transceiver station (BTS), mobile multihop relay (MMR)-BS, relay station (RS) that acts as a base station, base station A relay node (RN) that plays a role, an advanced relay station (ARS) that plays a role of a base station, a high reliability relay station (HR-RS) that plays a role of a base station, and a small base station And the like.

In addition, the terminal is a mobile terminal (MT), mobile station (mobile station, MS), advanced mobile station (advanced mobile station, AMS), high reliability mobile station (high reliability mobile station, HR-MS), subscription It may include a subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), user equipment (UE), and the like.

를 추정하기 위한 바이스태틱 거리(Bistatic Range, BR)에 대한 정보를 얻기 위하여 송신기들로부터 송출된 신호가 표적으로부터 반사된 반사 신호를 수신한다. 이때, 바이스태틱 거리란 도 1에 도시된 바와 같이 송신기들로부터 표적을 경유한 수신기들까지의 거리로서, 이에 대한 자세한 설명은 후술하기로 한다.Meanwhile, each receiver included in the distributed MIMO radar system 1 is the location of the target shown in FIG.

In order to obtain information on the bistatic range (BR) for estimating the signal, the signal transmitted from the transmitters receives the reflected signal reflected from the target. In this case, the bistatic distance is a distance from the transmitters to the receivers passing through the target as shown in FIG. 1, and a detailed description thereof will be described later.

2 is a block diagram of a target position estimation apparatus according to an embodiment of the present invention.

Referring to FIG. 2, a target position estimation apparatus 10 according to an embodiment of the present invention includes an input unit 100, a BR calculation unit 200, a modeling unit 300, and a position estimation unit 400.

The input unit 100 receives data on a reflected signal reflected from a target by a signal transmitted from the transmitters from the receivers.

The BR calculator 200 calculates a bistatic distance value by using data on reflected signals received from receivers. More specifically, the bistatic distance value is the distance from the transmitters to the receivers via the target as described above, and is the distance from the transmitters to the target and the distance from the target to the receivers as shown in Equation 1 below. It can be expressed as a sum.

은 제1 거리값,

는 송신기들로부터 표적까지의 거리값(이하, 제2 거리값),

은 표적으로부터 수신기들까지의 거리값이다.here,

Is the first distance value,

Is the distance value from the transmitters to the target (hereinafter, the second distance value),

Is the distance value from the target to the receivers.

The BR calculator 200 calculates the bistatic distance value by multiplying the propagation delay time of the received reflected signal by the propagation speed of the received reflected signal. Meanwhile, when noise is present in the received reflected signal, a bistatic distance value reflecting the noise may be calculated by Equation 2 below.

은 노이즈가 반영된 제1 거리값,

은 백색 잡음이다.here,

Is the first distance value reflecting the noise,

Is white noise.

As described above, the bistatic distance value calculated through the BR calculating unit 200 or the bistatic distance value reflecting the noise is used by the modeling unit 300 to model ellipsoids.

The modeling unit 300 models the ellipsoids by using the bistatic distance value calculated through the BR calculator 200. More specifically, the modeling unit 300 models the ellipsoids with the bistatic distance value as a major axis and the three-dimensional coordinate values of the transmitter and receiver as a focus by Equation 3 below.

이고,

이다.here,

ego,

to be.

Here, modeling the ellipsoids by the modeling unit may mean configuring an ellipsoid equation corresponding to Equation 3 above.

Referring to FIG. 3 showing the modeled ellipsoids, in a radar system 1 having one transmitter and two receivers, the bistatic distance value, which is the distance from the transmitter to the receiver via the target, is set as the long axis, and the transmitter/receiver It can be seen that two ellipsoids are modeled with their coordinate values as the focus. That is, the number of ellipsoids to be modeled is determined by the product of the number of transmitters and receivers (M x N).

Meanwhile, the modeling unit 300 may adjust the number of modeled ellipsoids according to a real-time change amount of the target position. The amount of change in the target position in real time may mean, for example, an amount of change in the target position per preset unit time interval. If the real-time variation of the target position is less than the preset threshold, it means that the variation of the target position is not large.Therefore, some transmitters and receivers are randomly selected from among all the transmitters and receivers included in the radar system (1). It is also possible to perform ellipsoid modeling only for receivers. (At this time, the number of ellipsoids to be modeled may be smaller than M x N.)

The position estimating unit 400 estimates the intersection point of the ellipsoids modeled through the modeling unit 300 as the position of the target. The intersection of the modeled ellipsoids can be obtained through solving a linear equation.

)들을 매개변수로 하는 선형 방정식으로 구성한다. 구성된 선형 방정식은 아래의 수학식 4와 같다.Referring to Equation 3 for the modeled ellipsoids, the position estimation unit 400 first uses Equation 3 as a variable related to the position of the target in order to obtain an intersection point (

) As parameters. The constructed linear equation is shown in Equation 4 below.

이고,here,

ego,

이고,

ego,

이다.

to be.

의 보조행렬

이고,At this time,

Auxiliary matrix of

ego,

이고,

ego,

이다.

to be.

Next, in order to obtain the solution of the linear equation defined by Equation 4, the least square method is used in which the square of the residual is minimized. Since the least-squares method is a generally well-known technique, a detailed description thereof will be omitted. The solution of the linear equation obtained by using the least squares method is shown in Equation 5 below.

의 네 번째 원소는 표적의 x 좌표값(

)이며, 다섯 번째 원소는 표적의 y 좌표값(

)이며, 여섯 번째 원소는 표적의 고도값인 z 좌표값(

)이다. 즉, 위치 추정부(400)는 상기 수학식 4에 의해 정의되는 선형 방정식 풀이를 통하여 타원체들의 교점을 표적의 3차원 좌표값으로서 산출하고, 상기 산출된 표적의 3차원 좌표값과 대응되는 값을 표적의 위치로 추정한다.Here, the solution of the linear equation

The fourth element of is the target's x coordinate value (

), and the fifth element is the target's y coordinate value (

), and the sixth element is the z coordinate value (

)to be. That is, the position estimating unit 400 calculates the intersection of the ellipsoids as a three-dimensional coordinate value of the target through solving a linear equation defined by Equation 4, and calculates a value corresponding to the calculated three-dimensional coordinate value of the target. It is estimated by the location of the target.

의 여섯 번째 원소인

) 대신에

의 세 번째 원소인

의 제곱근을 표적의 새로운 고도값으로 하여 표적의 위치를 추정할 수도 있다.On the other hand, the position estimating unit 400 is a z-coordinate value that is the altitude value of the target (that is, the solution of the linear equation

The sixth element of

) Instead of

The third element of

You can also estimate the position of the target by using the square root of as the new elevation value of the target.

More specifically, the specific condition may be determined according to a high standard deviation between transmitters and receivers. The high standard deviation between transmitters and receivers is defined by Equation 6 below.

는 송·수신기들의 평균 고도값이다.here,

Is the average altitude of the transmitter and receiver.

)을 표적위치로 추정하는 경우 앞서 언급한 종래의 기법(LS 기법 및 BRM 기법)이 가지는 고도값에 발생하는 오차에 대한 문제점을 보완할 수 없다.In this case, in the case of the distributed MIMO radar system 1 having a smaller altitude standard deviation, it can be regarded as a terrestrial antenna-based system or a complete terrestrial antenna-based system with little difference in altitude between the transmitter and receiver. In such a terrestrial antenna-based system or a complete terrestrial antenna-based system, the z coordinate value (

) Is estimated as the target position, the problem of the error occurring in the altitude value of the aforementioned conventional techniques (LS technique and BRM technique) cannot be compensated.

) 대신에 상기 선형 방정식의 해 중에서

의 제곱근을 표적의 새로운 고도값으로 하여 표적의 위치를 추정하고, 계산된 고도 표준편차가 기 설정된 임계값 이상이면 표적의 3차원 좌표값에 포함되는 표적의 고도값인 z 좌표값(

)을 이용하여 표적의 위치를 추정할 수 있다.Therefore, the positioning unit calculates the altitude standard deviation between the transmitters and receivers included in the distributed MIMO radar system 1, and is included in the 3D coordinate value of the target when the calculated altitude standard deviation is less than a preset threshold. The z coordinate value (

) Instead of

The square root of is used as the new altitude value of the target to estimate the position of the target, and if the calculated altitude standard deviation is greater than or equal to a preset threshold, the z-coordinate value (

) Can be used to estimate the position of the target.

Here, a storage unit (not shown) may be further included. The storage unit (not shown) includes data on the reflected signal reflected from the target by the signal transmitted from the transmitters, data on the transmitters and receivers (e.g., 3D coordinate values of transmitters and receivers) and a BR calculation unit. (200), the modeling unit 300 and the position estimation unit 400 to store the calculated result value.

4 is a flowchart of a method for estimating a target position according to an embodiment of the present invention. Hereinafter, a description of a part that overlaps with the previously described part will be omitted.

In step S510, the propagation delay time of the reflected signal is multiplied by the propagation speed of the reflected signal to calculate a bistatic distance value.

Step S520 is a step of modeling ellipsoids with the bistatic distance value calculated in step S510 as a major axis and the three-dimensional coordinate values of the transmitter and receiver as a focus. The number of ellipsoids modeled through step S520 is determined according to the number of transmitters and receivers. In addition, modeling may be performed by adjusting the number of modeled ellipsoids according to the amount of real-time change in the target position.

)들을 매개변수로 하는 선형 방정식을 구성하는 단계이다.In step S530, in order to find the intersection of the modeled ellipsoids, a variable related to the position of the target from the modeled ellipsoids (

This is the step of constructing a linear equation with parameters as parameters.

Step S540 is a step of obtaining a solution of a linear equation that is an intersection point of ellipsoids modeled using the least square method using the linear equation constructed in step S530.

Step S550 is a step of comparing a preset threshold value and an altitude standard deviation. To this end, it may further include the step of calculating the altitude standard deviation between the transmitters and receivers.

) 대신에 선형 방정식의 해 중에서

의 제곱근을 표적의 새로운 고도값으로 하여 표적의 위치를 추정할 수 있다.(S560a) 한편, 고도 표준편차가 기 설정된 임계값 이상이면 표적의 3차원 좌표값에 포함되는 표적의 고도값(

)을 이용하여 표적의 위치를 추정할 수 있다.(S560b)According to the comparison result, if the altitude standard deviation between the transmitters and the receivers is less than a preset threshold value, the altitude value of the target included in the three-dimensional coordinate value of the target from the solution of the linear equation obtained through step S540 (

) Instead of

The position of the target can be estimated by using the square root of as the new altitude value of the target (S560a). Meanwhile, if the altitude standard deviation is more than a preset threshold, the altitude value of the target included in the three-dimensional coordinate value of the target (

) Can be used to estimate the position of the target. (S560b)

5A is a diagram showing a layout diagram of transmitters and receivers to which a method for estimating a target position according to an embodiment of the present invention can be applied, and FIG. 5B is an estimation of each target position according to an elevation standard deviation of the transmitters and receivers shown in FIG. 5A. The performance of the method is shown.

5A and 5B, in a distributed MIMO radar system 1 including a transmitter and a receiver arranged as shown in FIG. 5A, the existing techniques (LS technique, BRM technique) and the present invention according to the high standard deviation of transmitters and receivers The altitude value of the target was calculated according to the method of estimating the target position according to an embodiment of the present invention, and performance was evaluated for the calculated altitude value. In the performance evaluation, the standard deviation of the measurement error of the bistatic distance (BR) was set to 10 m.

The index used in the performance evaluation is the average distance error, and is shown in Equation 7 below.

은 몬테카를로 시행 횟수이고,

는 i번째 몬테카를로 시행의 결과에서 얻어진 표적의 고도값을 의미한다.here,

Is the number of Monte Carlo trials,

Means the altitude value of the target obtained from the result of the ith Monte Carlo trial.

As can be seen from Fig. 5b, as the altitude standard deviation of the transmitter and receiver decreases (that is, the closer to a perfect terrestrial antenna-based system), the existing altitude estimation techniques, the LS technique and the BRM technique, have a distance error for the estimated altitude value. On the other hand, in the case of the method for estimating a target position according to an embodiment of the present invention, it can be seen that the method of estimating the target position shows stable estimation performance regardless of the standard deviation of altitude.

The apparatus described above may be implemented as a hardware component, a software component, and/or a combination of a hardware component and a software component. For example, the devices and components described in the embodiments include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA), It can be implemented using one or more general purpose computers or special purpose computers, such as a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications executed on the operating system. In addition, the processing device may access, store, manipulate, process, and generate data in response to the execution of software. For the convenience of understanding, although it is sometimes described that one processing device is used, one of ordinary skill in the art, the processing device is a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of these, configuring the processing unit to behave as desired or processed independently or collectively. You can command the device. Software and/or data may be interpreted by a processing device or to provide instructions or data to a processing device, of any type of machine, component, physical device, virtual equipment, computer storage medium or device. , Or may be permanently or temporarily embodyed in a transmitted signal wave. The software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable recording media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -A hardware device specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of the program instructions include not only machine language codes such as those produced by a compiler but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa.

As described above, although the embodiments have been described by the limited drawings, various modifications and variations are possible from the above description to those of ordinary skill in the art. For example, the described techniques are performed in an order different from the described method, and/or components such as a system, structure, device, circuit, etc. described are combined or combined in a form different from the described method, or other components Alternatively, even if substituted or substituted by an equivalent, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and claims and equivalents fall within the scope of the claims to be described later.

Claims (6)

(a) modeling ellipsoids with a bistatic range, which is a distance value from the transmitters to the receivers passing through the target, as a major axis and the three-dimensional coordinate values of the transmitters and receivers as a focus; And
(b) estimating the intersection of the modeled ellipsoids as the location of the target,
Step (b)
(b-1) Variables related to the position of the target from the modeled ellipsoids (

) Constructing a linear equation with parameters as parameters; And
(b-2) obtaining a solution of the constructed linear equation using the least square method, and estimating a value corresponding to the three-dimensional coordinate value of the target among the solutions of the linear equation as the position of the target Further comprising,
Target location estimation method.
The method of claim 1,
The bistatic distance value is calculated by multiplying a propagation delay time of a reflected signal, which is a signal reflected from the target, by a signal transmitted from the transmitters, by a propagation speed of the reflected signal.
delete The method of claim 1,
The step (b-2) is
If the altitude standard deviation between the transmitters and the receivers is less than or equal to a preset threshold value, in the solution of the linear equation instead of the altitude value of the target included in the three-dimensional coordinate value of the target

The target position is estimated by using the square root of as the new altitude value of the target, and if the altitude standard deviation is greater than or equal to a preset threshold value, the target altitude value included in the three-dimensional coordinate value of the target is used. Target position estimation method to estimate the position of
The method of claim 4,
The elevation standard deviation is a method of estimating a target location defined by Equation 1.
[Equation 1]

here,

Is the elevation standard deviation,

Is the number of transmitters,

Is the number of receivers,

Is the altitude value of the transmitter and receiver,

Is the average altitude value of the transmitter and receiver.
The method of claim 1,
Step (a)
A method for estimating a target position for controlling the number of the modeled ellipsoids according to the amount of change in the position of the target.

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