JP2002107449A - Probe radar and probing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a probe radar and a probing method while considering the directivity of an antenna. SOLUTION: This probe radar 1 is provided with a means 11 for computing a predicted micro line segment by using a predicted parameter based on one end of a precise micro line segment showing a part of the shape of a target, a means 12 for computing the predicted time to be required for going and returning of the probe wave between the predicted micro line segment and an observation point, a means 13 for computing a predicted amplitude value to be observed at the observation point when the prove wave is reflected by the predicted micro line segment, a means 14 for outputting the amplitude value of the received reflected wave as an observation amplitude value, a means 15 for computing a first navigation mark showing a coincidence of the observation amplitude value obtained by using the predicted parameter with the predicted amplitude value, and a means 16 for discriminating a predicted micro line segment showing the highest coincidence from among the first navigation mark computed in relation to plural predicted parameters and for using this predicted micro line segment as a precise micro line segment showing a part of the shape of the target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a search radar and a search method for searching for a target, and more particularly, to an underground radar and a search method using the underground radar for searching for a target buried in the ground.

[0002]

2. Description of the Related Art Underground radars utilizing search waves such as microwaves are widely used to search for objects buried underground. Such an underground radar has the advantage of being able to probe underground at high speed without contact and without destruction. On the other hand, reflection loss due to the ground surface of the exploration wave and propagation loss in the ground are large, and the exploration beam is spread and poor in directivity, so that the horizontal resolution is poor and the maximum detection distance is disadvantageously limited. Therefore, advances in signal processing methods have become important along with hardware ideas.

[0003]

The search results obtained by the underground radar are displayed as an underground radar image. At this time, the underground radar image is created ignoring the directivity characteristics of the microwave antenna. In other words, ignoring the directional characteristics of each antenna, an image relating only to the direction directly below the search radar is created for each observation point using the amplitude value of the reflected wave, and these images are arranged side by side to create an underground radar image as a whole. , Poor horizontal resolution. Therefore, in order to improve the horizontal resolution of the underground radar image, signal processing such as synthetic aperture processing, zero-cross synthetic aperture processing, migration processing, or pulse compression processing has been studied.

[0004] However, the horizontal resolution of such signal processing is not yet satisfactory, and it is difficult to grasp the shape of the buried object from the obtained underground radar image, even if it is possible. There is a problem that there is. In the method of creating an underground radar image ignoring the directional characteristics of the antenna, it is necessary to perform continuous measurement because the transmitting and receiving antennas must be located close enough and must be observed linearly. There is a problem that it is not suitable for difficult terrain.

Accordingly, an object of the present invention is to solve the above problems,
It is an object of the present invention to provide a search radar and a search method that can improve the horizontal resolution and easily adapt to the surrounding environment of an observation point.

[0006]

In order to achieve the above object, according to a first aspect of the present invention, at a plurality of observation points, a search wave is transmitted toward a search area and reflected by a target object. An exploration radar that searches for a target object by observing a wave uses a predetermined minute line segment that represents a part of the shape of the target object as a reference point, and uses the prediction minute line segment using an arbitrary prediction parameter. A predicted minute line segment calculating means for calculating the estimated minute line segment, a predicted time calculating unit for calculating a predicted time required for the exploration wave to reciprocate between the predicted minute line segment and the observation point, and a search wave using the predicted time. Corresponds to the predicted amplitude value calculation means that calculates the predicted amplitude value that is predicted to be observed at the observation point when the light is reflected by the predicted minute line segment, and the reception time from the transmission start time of the exploration wave To read the expected time When the value is obtained, the observation amplitude value output unit that outputs the amplitude value of the reflected wave received at the prediction time as the observation amplitude value indicates the coincidence between the observation amplitude value and the prediction amplitude value obtained using the prediction parameter. A first index calculating unit that calculates a first index, and a first index that shows the highest consistency among the first indexes calculated for the plurality of prediction parameters, and discriminates the first index. A determined minute line segment output means for outputting a predicted minute line segment calculated using the prediction parameter corresponding to the index as a further determined minute line segment representing a part of the shape of the target object.

In this search radar, one end of the determined minute line segment output by the determined minute line segment output unit is used as a further reference point in the predicted minute line segment calculation unit in order to reproduce an image of the shape of the inspection object. Further, there is further provided image forming means for forming an image of the shape of the target using a series of determined minute line segments obtained when the process of obtaining further determined minute line segments is repeated.

In a second aspect of the present invention, a search radar for searching for a target by transmitting a search wave toward a search area and observing a reflected wave reflected from the target at a plurality of observation points. A predicted minute line segment calculating means for calculating a predicted minute line segment using an arbitrary prediction parameter, using one end of an already determined confirmed minute line segment representing a part of the shape of the target object as a reference point, Prediction time calculation means for calculating a prediction time required for the exploration wave to reciprocate between the minute and the observation point, and the prediction time when the exploration wave is reflected by the predicted minute line segment using the prediction time. Predicted amplitude value calculating means for calculating an amplitude value predicted to be observed as a predicted amplitude value, and when the reception time from the transmission start time of the exploration wave is replaced with the corresponding predicted time, the received value is received at the predicted time. Was Indicates the coincidence between the observation amplitude value output means for outputting the amplitude value of the emission wave as the observation amplitude value and the predicted amplitude value obtained by using the prediction parameter and multiplied by the observation amplitude value and an arbitrary matching parameter. A second index calculating unit that calculates a second index; and a second index that shows the highest consistency among the second indexes calculated for the plurality of prediction parameters, and discriminates the second index. A predicted minute line segment calculated using the prediction parameter corresponding to the index, a provisional minute line segment output means for outputting as a provisional minute line segment, and one end of the provisional minute line segment output by the provisional minute line segment output means. When the process of obtaining a further provisional minute line segment by setting it as a further reference point in the predicted minute line segment calculation means is repeated,
Provisional amplitude value sequence output means for outputting a sequence of predicted amplitude values corresponding to the obtained sequence of provisional minute line segments as a provisional amplitude value sequence, and a sequence obtained by using a received reflection wave amplitude value sequence and a matching parameter. A third index calculating means for calculating a third index indicating a match with the determined provisional amplitude value series, and indicating the highest match among the third indexes calculated for the plurality of matching parameters A determined minute line that discriminates the third index and outputs a series of provisional minute lines calculated using the matching parameter corresponding to the third index as a series of determined minute lines representing the shape of the target. Segment output means.

In order to reproduce an image of the shape of the object to be inspected, this search radar uses the sequence of determined minute line segments output by the defined minute line segment sequence output means to form the image of the shape of the target object. Means are further provided. According to the present invention, in consideration of the directional characteristics of the transmitting and receiving antennas of the search radar,
Since an image of the shape of the target is formed, a more reliable image with improved horizontal resolution can be obtained as a search result.

Further, according to the present invention, since an image is formed using a specular reflection model taking into account the directional characteristics of the transmitting and receiving antennas, the number of observation points can be increased to shorten the installation interval of each observation point. The more you do, the more adaptive your search radar will be to the surrounding environment of the station.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic principle of a search radar according to the present invention will be described. Here, a case will be described in which a target buried in the ground is searched from a plurality of observation points on the ground using an exploration radar that is an observation device and an image is formed. It is also applicable when present.

In general, a search radar transmits a search wave such as a microwave toward a search area at a plurality of observation points on the ground, and observes an amplitude value of a reflected wave reflected by a target. Data relating to the amplitude values of observation waves at a plurality of observation points is recorded in advance, and the position and shape of the target are estimated based on the observed amplitude values. The exploration radar according to the present invention, among a plurality of amplitude values that can be predicted and calculated using a predetermined prediction model when it is assumed that the exploration wave has reflected on a minute line segment, By discriminating the one having the highest coincidence, the minute line segment at this time is regarded as being closest to a part of the shape of the target object, and the minute line segments thus obtained are joined to form the shape of the target object. It is characterized by constituting an image. For the calculation of the predicted amplitude value, a specular reflection model, which will be described later, taking into account the directivity and the like of the transmitting / receiving antenna is used. In the present invention, for example, a microwave is used as a search wave.

In the first embodiment of the present invention, first, an amplitude value expected to be observed at the observation point when a search wave is reflected by a certain minute line segment is calculated as a predicted amplitude value. . A plurality of these minute line segments are assumed, and the corresponding predicted amplitude values are calculated. Next, from among the predicted amplitude values calculated for each minute line segment, the predicted amplitude value having the highest matching with the observed amplitude value that is the actually observed amplitude value is discriminated. Then, it is determined that the minute line segment corresponding to the predicted amplitude value having the highest matching is a part of the shape of the target. A plurality of minute line segments determined in this way are obtained, and these are joined to form an image of the shape of the target.

The second embodiment of the present invention is a further extension of the first embodiment. First, substantially in the same manner as in the first embodiment, a plurality of determined minute line segments are connected to each other to obtain a plurality of provisional minute line segment sequences of a target. A plurality of provisional minute line segment sequences are calculated, and a corresponding predicted amplitude value sequence is calculated. Next, from the series of predicted amplitude values calculated for each minute line segment, the one that shows the highest overall consistency with the actually observed series of observed amplitude values is discriminated. Then, it is assumed that the provisional minute line segment sequence corresponding to the sequence of the predicted amplitude values indicating the highest coincidence is closest to the shape of the actual target. In the second embodiment, this is used to construct an image of the shape of the target.

First, a search radar according to a first embodiment of the present invention will be described. FIG. 1 is an explanatory view of the operation principle of the search radar according to the present invention, FIG. 2 is a block diagram of the search radar according to the first embodiment of the present invention, and FIG. 3 is a search according to the first embodiment of the present invention. It is a flowchart of operation | movement of a radar. For the sake of simplicity, a two-dimensional problem as shown in FIG. 1 is dealt with here, but a three-dimensional problem can be similarly discussed.

As shown in FIG. 2, in the search radar 1 according to the first embodiment of the present invention, one end of an already-determined determined minute line representing a part of the shape of a target is set as a reference point, and an arbitrary prediction is performed. A predicted minute line segment calculating means 11 for calculating a predicted minute line segment using parameters, and a predicted time calculating means 12 for calculating a predicted time required for a search wave to reciprocate between the predicted minute line segment and the observation point. A predicted amplitude value calculating means 13 for calculating, as a predicted amplitude value, an amplitude value predicted to be observed at the observation point when the exploration wave is reflected by a predicted minute line segment using the predicted time; When the reception time from the transmission start time of the wave is replaced with the corresponding prediction time, the observation amplitude value output means 14 that outputs the amplitude value of the reflected wave received at the prediction time as the observation amplitude value; for Observed amplitude values obtained Te and and a first index calculating means 15 for calculating a first index indicating the consistency of the predicted amplitude values.

As will be described later, a predicted minute line segment is calculated for each of a plurality of prediction parameters. However, the search radar 1 according to the first embodiment further includes a second calculation unit for each of the plurality of prediction parameters. The first index indicating the highest consistency is discriminated from among the one index, and a predicted minute line segment calculated using the prediction parameter corresponding to the first index is defined as:
Fixed minute line segment output means 16 for outputting as a further fixed minute line segment representing a part of the shape of the target, and one end of the determined minute line segment output by the fixed minute line segment output means 16 The image forming unit 17 that forms an image of the shape of the target using the series of determined minute line segments obtained by repeating the process of obtaining a further determined minute line segment by using the reference point as a further reference point in FIG. Prepare.

Each of these means is realized by using an arithmetic processing device such as a computer. Next, the operation of the search radar according to the first embodiment of the present invention will be described. Also in the first embodiment of the present invention, a search wave is transmitted from a search radar at a plurality of observation points and a reflected wave is observed. The number of observation points is defined as N. Further, the number of minute line segments for forming an image of the entire shape of the target is M. Specific examples of the respective numbers include N = 400, M = 100000, etc., but these numbers do not limit the present invention.
However, the greater the number, the higher the accuracy of image composition. Data relating to the amplitude value of the observation wave at each observation point i (i = 1 to N) is observed in advance before the image formation processing. Specifically, the amplitude value of the reflected wave observed by the receiving antenna is recorded in a table in correspondence with the reception time from the transmission start time of the search wave. This table is created for each observation point.

In step S101 of FIG. 3, first,
Set a reference point for image composition. This reference point is referred to herein as a reconstruction reference point. The reconstruction reference point is one of the points at both ends of a minute line segment that has already been determined to represent a part of the shape of the target (hereinafter, referred to as a determined minute line segment). (Referred to as a fixed point). The determined minute line segment will be described later. At the start of image processing when there is no fixed point on the target, the reconstruction reference point may be appropriately determined with reference to the already observed observation amplitude value data.

Next, in step S102, a prediction parameter φ is set. In the present invention, the other point (hereinafter, referred to as a predicted point) of a predicted minute line segment (hereinafter, referred to as a predicted minute line segment) having the reconstruction reference point as one point.
Predict the position of. The prediction parameter φ is a parameter used for this prediction. When the determined point of the determined minute line segment is set as the reconstruction reference point (x _k , z _k ) on the two-dimensional plane coordinates as described above, The direction on the coordinate plane (that is, the angle on the xz plane in FIG. 1) of the predicted minute line segment having the length Δ, which is a predicted minute line segment that can be predicted from the reconstruction reference point (x _k , z _k ) Parameters. Therefore, it can be said that the candidate of the prediction point is on the circumference of the radius Δ centered on the reconstruction reference point (x _k , z _k ), and if one prediction parameter φ is set, one prediction point is obtained. Will be decided. Although the two-dimensional problem is dealt with here, in the case of three-dimensional, the prediction point candidate is on a spherical surface having a radius Δ centered on the reconstruction reference point (x _k , z _k ).

Next, in step S103, a predicted point is calculated. When dealing with a two-dimensional problem, prediction points (x _{k + 1} , z _{k + 1} ) that can be predicted from the reconstruction reference points (x _k , z _k )
Is expressed by the following equation using the above-described prediction parameter φ.

[0022]

(Equation 9)

Thus, a predicted minute line segment is defined between the reconstruction reference point (x _k , z _k ) and the prediction point (x _{k + 1} , z _{k + 1} ). Next, in step S104, a predicted time required for the search wave to reciprocate between the observation point and the predicted minute line segment is calculated. This estimated time corresponds to the time from the start of the transmission of the search wave to the reception of the reflected wave by the receiving antenna, assuming that the search wave is reflected by the predicted minute line segment.

In FIG. 1, the estimated time can be calculated, for example, as follows. The reflection of the exploration wave at the predicted minute line segment is based on the reconstruction reference point (x _k , z _k ) and the predicted point (x _{k + 1} ,
z _{k + 1} ) and the midpoint (x _p ,
z _p ).

[0025]

(Equation 10)

The coordinates of the transmitting antenna at observation point i are represented by T (x _Ti , 0), and the coordinates of the receiving antenna are represented by R (x _Ri ,
0), assuming that the propagation speed of the microwave in the ground is V, the predicted time τ is represented by Expression (11).

[0027]

[Equation 11]

Next, a predicted amplitude value is calculated in step S105. The predicted amplitude value is an amplitude value expected to be observed at the observation point when it is assumed that the exploration wave is reflected at a certain predicted minute line segment. Generally, an exploration wave transmitted from a transmission antenna of an exploration radar is reflected by a target and observed by a reception antenna. The amplitude value of the reflected wave depends on the shape of the target, the transmission antenna on the observation point, and It is affected by various effects such as the position and directional characteristics of the receiving antenna, the relative dielectric constants of the underground and the target, the propagation speed and wavelength of the search wave, and the attenuation characteristics of the search wave to the ground.

In the present invention, therefore, based on the above fact,
As a prediction model for calculating the amplitude value, for example,
The so-called mirror surface reflection taking into account the directional characteristics of the antenna
Use the injection model. FIG. 4 is a diagram illustrating a specular reflection model.
It is. As shown in FIG.
(X_T, 0) and the coordinates of the receiving antenna are R (x_R, 0), Ma
The attenuation rate of microwaves in the ground is λ,
Is a function representing the attenuation characteristic with respect to the distance l at f
(L), θ from transmitting antenna _TObject 10 in the direction of
The upper point P (x_P, Z_PConsidering the microwave reflected by)
The function representing the directional characteristic of the transmitting antenna
(Θ_T), A function representing the directional characteristic of the receiving antenna is g
(Θ_R), A function that indicates the directional characteristics of the target that reflects the
Let g (θ_P), The reflection coefficient of the target is γ,
The electric power is ε_O, The relative permittivity underground is ε_O, And specular reflection
Amplitude predicted by model u_i(Τ) is expressed by equation (12).
Is done.

[0030]

(Equation 12)

Next, in step S106, the reception time from the transmission start time of the search wave is replaced with the predicted time τ obtained in step S104, and the amplitude value of the reflected wave received in the predicted time τ is related to the observation point. It is read from the table and output as the observed amplitude value Fi (τ). When an impulse-like microwave is transmitted as a search wave, for example, the observed reflected wave is ideally an impulse-like waveform delayed by the time required for the microwave to reciprocate between the observation point and the target. It is. But in fact,
The shape of the target, the position and directivity of the transmitting and receiving antennas at the observation point, the relative permittivity of the ground and the target, the propagation speed and wavelength of the exploration wave, and the attenuation characteristics of the exploration wave to the ground Under the various conditions described above, even if an impulse-like search wave is transmitted, the amplitude value of the reflected wave observed by the receiving antenna has a distribution having a certain temporal width.
Therefore, in the present invention, in order to extract the amplitude value of the observation wave to be compared with the predicted amplitude value, the predicted time obtained in step S104 is used. Note that the observed amplitude value s _i (τ) output in step S106 is usually an amplitude value near the peak value in the amplitude value sequence recorded in the table.

In step S107, all observation points i
(I = 1 to N), a predicted time τ and a predicted amplitude value u
_It is determined whether _i (τ) and the observed amplitude value s _i (τ) have been determined. Steps S104 to S1 until obtained
06 is repeated. In the present invention, one prediction point determined by one prediction parameter φ, in other words, one predicted minute line segment is obtained for a plurality of observation points. Therefore, if there are N observation points, the predicted time τ and the predicted amplitude value u _i
(Τ) and N observation amplitude values s _i (τ) are obtained.

In step S108, all observation points i
A first index I for evaluating the consistency between the predicted amplitude value u _i (τ) and the observed amplitude value s _i (τ) at the predicted time τ over (i = 1 to N) is calculated. This first index I
Is, in the first embodiment,

[0034]

(Equation 13)

The other evaluation function may be defined as long as it can determine the coincidence. Equation (13)
As can be seen from the prediction in the prediction time τ amplitude value u _i
The value of the first index I decreases as the agreement between (τ) and the observed amplitude value s _i (τ) increases. In other words, as the first index I is smaller, the predicted amplitude value u _i (τ) and the observed amplitude value s _i
The agreement with (τ) is high, that is, the predicted minute line segment at this time is closer to a part of the actual shape of the target.

Steps S102 to S108 described above
Is calculated using a certain prediction parameter φ.
One predicted point, that is, one predicted minute line segment
The first index for assessing gender is to be determined.
You. In the present invention, each prediction for a plurality of prediction parameters φ is
Predicted amplitude value u of the minute line segment _iFind (τ) respectively
However, step S109 is a determination step for this purpose.
And a prediction for a given number of prediction parameters φ
Amplitude value u_iStep S1 until all (τ) are obtained.
02 to S108 are repeated. Number of prediction parameters φ
The greater the number, the greater the discrimination in step S110 described below.
Since the population at the time of processing becomes large, the accuracy of image composition
improves. For a given number of prediction parameters φ,
The measured amplitude value is obtained, and each predicted amplitude value and the corresponding observed amplitude
The first index I indicating the agreement with the value over each observation point is
After the calculation, the process proceeds to step S110.

In step S110, the first index I obtained as described above is evaluated. Therefore, the first index I calculated for a plurality of prediction parameters is discriminated from the first index I having the highest degree of coincidence.
When the first index is defined by Expression (13), it is determined that the coincidence between the predicted amplitude value and the observed amplitude value is the highest when the first index I is the minimum.

Next, in step S111, the predicted point determined to have the highest coincidence is output as a further fixed point. In other words, the predicted minute line segment defined between the fixed point and the reconstruction reference point used as the reference for obtaining the fixed point becomes a further minute line segment. Step S112 is a determination step for the purpose of obtaining a plurality of confirmed minute line segments, and a predetermined number (here, M)
Steps S101 to S111 are repeated until the determined minute line segment is obtained. Here, step S
If the determined point output at 111 is used as a new reconstruction reference point set at step S101, a plurality of mutually adjacent determined minute line segments can be obtained. When a predetermined number of determined minute line segments are obtained, the process proceeds to step S113.

In step S113, a plurality of determined minute line segments obtained as described above are connected to form an image of the shape of the target. The image of the configured shape of the target may be displayed on a display screen or on paper. As described above, according to the first embodiment of the present invention, a plurality of amplitude values that can be predicted and calculated using a predetermined prediction model when it is assumed that a search wave is reflected by a minute line segment are obtained. From the above, discriminating the one having the highest agreement with the actually observed amplitude value, and considering the minute line segment at this time as being closest to a part of the shape of the target object, a plurality of minute line segments obtained by Since the image of the shape of the target is formed by joining, the smaller the minute line segment is, the more reliable the image with improved horizontal resolution can be obtained as a search result.

Further, according to the present invention, since an image is formed using a specular reflection model in which the directivity characteristics of the transmitting and receiving antennas of the search radar are taken into account, the number of observation points is increased and the installation interval of each observation point is increased. The shorter the is, the more adaptive the search radar will be to the surrounding environment of the station. Next, a search radar according to a second embodiment of the present invention will be described.

FIG. 5 is a block diagram of the search radar according to the second embodiment of the present invention, and FIG. 6 is a flowchart of the operation of the search radar according to the second embodiment of the present invention. For the sake of simplicity, the two-dimensional problem is handled in the same manner as in the first embodiment, but the three-dimensional problem can be discussed in the same manner. The second embodiment of the present invention is the first embodiment.
Is a further extension of the embodiment of FIG. That is, in the first embodiment, the minute line segment closest to a part of the shape of the target is obtained, and the shape of the entire target is estimated by connecting a plurality of these. In the second embodiment, A plurality of tentative minute line segments of the target obtained by connecting a plurality of these minute line segments are further obtained, and the one closest to the actual shape of the target is determined to be the shape of the target. I do.

As shown in FIG. 5, the search radar 1 according to the second embodiment of the present invention uses an end point of an already-determined determined minute line representing a part of the shape of a target as a reference point, and performs arbitrary prediction. A predicted minute line segment calculating means 11 for calculating a predicted minute line segment using parameters, and a predicted time calculating means 12 for calculating a predicted time required for a search wave to reciprocate between the predicted minute line segment and the observation point. A predicted amplitude value calculating means 13 for calculating, as a predicted amplitude value, an amplitude value predicted to be observed at the observation point when the exploration wave is reflected by a predicted minute line segment using the predicted time; When the reception time from the transmission start time of the wave is replaced with the corresponding prediction time, the observation amplitude value output means 14 that outputs the amplitude value of the reflected wave received at the prediction time as the observation amplitude value; for It was collected using, and a second index calculating means 21 for calculating the predicted amplitude values obtained by multiplying the observed amplitude and an arbitrary alignment parameter, a second index indicating the consistency of.

As in the first embodiment, predicted minute line segments are calculated for a plurality of prediction parameters, respectively. However, the search radar 1 according to the second embodiment is calculated for a plurality of prediction parameters. The second index indicating the highest consistency is discriminated from the second indexes, and a predicted minute line segment calculated using the prediction parameter corresponding to the second index is defined as:
Provisional minute line segment output means 22 for outputting as a provisional minute line segment
And when the process of obtaining a further provisional minute line segment by using one end of the provisional minute line segment output by the provisional minute line segment output unit 22 as a further reference point in the predicted minute line segment calculation unit 11 is repeated. Using a provisional amplitude value sequence output unit 23 that outputs a sequence of predicted amplitude values corresponding to the obtained sequence of provisional minute line segments as a provisional amplitude value sequence, and a sequence of amplitude values of the received reflected wave and matching parameters. And a third index calculating means 24 for calculating a third index indicating the coincidence with the provisional amplitude value sequence obtained as described above.

As will be described later, a predicted minute line segment is calculated for each of a plurality of prediction parameters. The search radar 1 according to the second embodiment calculates the third minute line segment calculated for a plurality of matching parameters. A third index indicating the highest agreement is discriminated from the indexes, and a series of provisional minute line segments calculated using the matching parameter corresponding to the third index is
A determined minute line segment output unit 25 that outputs the determined minute line segment sequence representing the shape of the target, and a shape of the target object using the determined minute line sequence output by the determined minute line segment output unit 25 Is further provided with an image forming means 17 for forming an image.

Each of these means is realized by using an arithmetic processing device such as a computer. In FIGS. 5 and 6, means and steps for executing substantially the same processing as in FIGS. 2 and 3 are denoted by the same reference numerals, and these means and steps are already described in the first embodiment. Therefore, detailed description is omitted.

Next, the operation of the search radar according to the second embodiment of the present invention will be described. In the second embodiment of the present invention, as in the first embodiment, data relating to the amplitude value of the observation wave at each observation point i (i = 1 to N) is observed before the image forming process. . That is, the amplitude value of the reflected wave observed by the receiving antenna is recorded in the table in correspondence with the reception time from the start of the transmission of the search wave. This table is created for each observation point.

In step S201 of FIG. 6, first,
Set matching parameters. In the first embodiment, the predicted amplitude value u at the predicted time τ at all observation points i
_{Although the} evaluation function represented by Expression (13) is defined as a first index for evaluating the coincidence between _i (τ) and the observed amplitude value s _i (τ), in the second embodiment, further matching is performed. Parameter ρ
To expand equation (13),

[0048]

[Equation 14]

Is calculated as a second index. The details will be described later. Next, step S1
At 01, a reconstruction reference point is set as a reference point for image composition. The reconstruction reference point is a provisional point which is one of the two ends of a provisional minute line segment described later. Next, in step S102, a prediction parameter φ is set.

Next, in step S103, a predicted point is calculated. As described above, this predicted point is another point for forming the predicted minute line segment when the reconstruction reference point set in step S101 is set as one point of the predicted minute line segment. Next, in step S104, a predicted time required for the search wave to reciprocate between the observation point and the predicted minute line segment is calculated. As described above, the predicted time corresponds to the time from the start of the transmission of the search wave to the reception of the reflected wave by the receiving antenna, assuming that the search wave is reflected by the predicted minute line segment. It is. Also in the second embodiment, as in the first embodiment, the reflection of the search wave at the predicted minute line segment approximates to that occurring at the midpoint between the reconstruction reference point and the predicted point.

Next, in step S105, a predicted amplitude value is calculated. For the calculation of the predicted amplitude value, a specular reflection model represented by Expression (12) is used as in the first embodiment.
Next, in step S106, the reception time from the transmission start time of the search wave is replaced with the predicted time τ obtained in step S104, and the amplitude value of the reflected wave received at the predicted time τ is read from the table relating to the observation point. , And output as the observed amplitude value s _i (τ).

Next, in step S107, it is determined whether the predicted time τ, the predicted amplitude value u _i (τ), and the observed amplitude value s _i (τ) have been obtained for all the observation points i. Steps S104 to S106 are repeated until all are obtained. Therefore, if there are N observation points, the prediction time τ and the prediction amplitude value u for one prediction parameter φ
_i (tau) and observed amplitude value s _{i (τ)} is obtained by N each.

In step S202, all observation points i
, A second value for evaluating the coincidence between the predicted amplitude value u _i (τ) and the observed amplitude value s _i (τ) at the predicted time τ.
Is calculated. This second index Iρ is calculated by the equation (1)
As defined in 4), the higher the matching between the observed amplitude value s _i (τ) at the predicted time τ and the predicted amplitude value u _i (τ) obtained by multiplying the matching parameter ρ, the higher the value of the second index Iρ Becomes smaller.

Step S109 is a determination step for obtaining a predicted amplitude value u _i (τ) of each predicted minute line segment for a plurality of predicted parameters φ. Steps S102 to S202 are repeated until a predicted amplitude value u _i (τ) for a predetermined number of prediction parameters φ is obtained.
The larger the number of prediction parameters φ, the larger the set of prediction parameters φ indicating the highest consistency between the predicted minute line segments over the entire observation point in the discrimination processing in step S203 described later. The accuracy is improved.

When the predicted amplitude values for a predetermined number of prediction parameters φ are obtained, and the second index Iρ indicating the consistency between each predicted amplitude value and the corresponding observed amplitude value is calculated,
Proceed to step S203. In step S203, the evaluation regarding the second index Iρ obtained as described above is performed. That is, the second index Iρ calculated for the plurality of prediction parameters φ is discriminated from the second index Iρ having the highest coincidence. Specifically, when the second index Iρ defined by Expression (14) is the minimum, it is determined that the coincidence between the predicted amplitude value and the observed amplitude value is the highest.

In step S204, the predicted point determined to have the highest coincidence is output as a provisional point. A predicted minute line segment defined between the provisional point and the reconstruction reference point used as a reference for obtaining the provisional point is a further provisional minute line segment. Step S112 is a determination step for the purpose of obtaining a plurality of provisional minute line segments. Steps S101 to S204 are repeated until a predetermined number (here, M) of provisional minute line segments are obtained. Here, if the provisional point output in step S204 is used as the new reconstruction reference point set in step S101, a plurality of provisional minute line segments adjacent to each other can be obtained. When a predetermined number of provisional minute line segments are obtained, the process proceeds to step S205.

In step S205, a plurality of temporary minute line segments obtained as described above are connected to form a temporary minute line sequence of a target (hereinafter, referred to as a temporary minute line sequence). I do. Next, in step S206, a third index indicating the matching between the provisional minute line segment sequence obtained using the matching parameters and the actual actual shape is calculated.

As described above, a search radar generally estimates the shape and position of a target object based on data relating to the amplitude values of reflected waves from the target object observed at a plurality of observation points. That is, the data obtained at the observation point is only the amplitude value of the reflected wave distributed over time. Therefore, in the third index, a sequence of predicted amplitude values corresponding to the provisional minute line segment sequence (hereinafter, referred to as a provisional amplitude value sequence),
The function indicates the coincidence with the series of observation amplitude values over the observation time during which the reflected wave can be observed at each observation point. Specifically, the third index indicates that the observation point is i = 1,
2,..., N, the observation time at which the reflected wave can be observed at each observation point i is T _i , the sequence of the observed amplitude values over the observation time T _i is S _i (t), and the provisional amplitude value sequence is U _i ( t),

[0059]

(Equation 15)

E is defined as By the above-described steps S101 to S206, one provisional minute line segment sequence, in other words, a provisional amplitude value sequence is determined for a certain matching parameter ρ, and a third index for evaluating the validity is determined. Is determined. In the second embodiment, a plurality of such provisional minute line segment sequences are obtained. Step S2
Reference numeral 07 denotes a determination step for this purpose, in which a provisional amplitude value series for a predetermined number of matching parameters ρ is obtained, and a third index corresponding thereto is obtained. The greater the number of matching parameters ρ, the more step S208 described later
Since the population at the time of classifying the matching parameter ρ showing the highest matching in the above becomes large, it leads to improvement in the accuracy of the image configuration.

In step S208, the third index E is evaluated. That is, the third index E calculated for the plurality of matching parameters ρ is discriminated from the third index E having the highest matching. When the third index E is the minimum, it is determined that the consistency between the sequence of the amplitude values of the received reflected wave and the provisional amplitude value sequence is the highest. Then step S
In 209, the provisional minute line segment sequence calculated using the matching parameter ρ when it is determined that the coincidence is the highest is output as the final minute line segment sequence closest to the actual shape of the target.

In step S113, an image of the shape of the target is formed using the determined minute line segment sequence obtained as described above. The image of the configured shape of the target may be displayed on a display screen or on paper. As described above, according to the second embodiment of the present invention, a plurality of provisional overall shapes of the target are calculated by connecting the minute line segments obtained using the second index, and Among them, the one that shows the highest agreement with the actually observed amplitude value over the entire shape is discriminated using the third index, and it is regarded as the entire shape of the target, so that higher accuracy is achieved. Image can be obtained.

[0063]

According to the present invention, since the image of the shape of the target is formed in consideration of the directional characteristics of the transmitting and receiving antennas of the search radar, a more reliable image with improved horizontal resolution is obtained as the search result. be able to. In addition, according to the present invention, since the image is configured using a specular reflection model that takes into account the directional characteristics of the transmitting and receiving antennas, the more the number of observation points is increased and the shorter the installation interval of each observation point is, the more the image is configured. In addition, the applicability of the exploration radar to the surrounding environment of the observation point is improved.

In the second embodiment of the present invention, a plurality of provisional overall shapes of the target are calculated by connecting the minute line segments obtained using the second index, and the actual shape of the target is calculated. The one that shows the highest agreement over the entire observed shape with the observed amplitude value is discriminated using the third index, and it is regarded as the entire shape of the target object. Further, a highly accurate image can be obtained.

The search radar according to the present invention can be applied not only to the search for a target buried in the ground but also to the search for a target existing in the air or underwater.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an operation principle of a search radar according to the present invention.

FIG. 2 is a block diagram of a search radar according to the first embodiment of the present invention.

FIG. 3 is a flowchart of an operation of the search radar according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a specular reflection model.

FIG. 5 is a block diagram of a search radar according to a second embodiment of the present invention.

FIG. 6 is a flowchart of the operation of the search radar according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exploration radar 11 ... Predicted minute line segment calculating means 12 ... Predicted time calculating unit 13 ... Predicted amplitude value calculating unit 14 ... Observed amplitude value calculating unit 15 ... First index calculating unit 16 ... Definite minute line segment calculating unit 17 ... Image construction means 21 Second index calculation means 22 Temporary minute line segment output means 23 Temporary amplitude value series output means 24 Third index calculation means 25 ... Confirmed minute series output means

Claims (18)

[Claims] An exploration radar for exploring the target by transmitting an exploration wave toward an exploration area and observing a reflected wave reflected by the target at a plurality of observation points, A predicted minute line segment calculating means for calculating a predicted minute line segment using an arbitrary prediction parameter, using one end of the already determined confirmed minute line segment representing a part of the shape as a reference point, Prediction time calculation means for calculating a prediction time required for the search wave to reciprocate between the observation point and the prediction time, and using the prediction time, when the search wave is reflected by the predicted minute line segment, the observation is performed. Predicted amplitude value calculation means for calculating an amplitude value predicted to be observed at a point as a predicted amplitude value, and when the reception time from the transmission start time of the exploration wave is replaced with the corresponding predicted time, the predicted time To An amplitude output means for outputting the amplitude value of the reflected wave received as an observed amplitude value, and a first value indicating the coincidence between the observed amplitude value and the predicted amplitude value obtained using the prediction parameter. First index calculating means for calculating an index; and the first index calculated for a plurality of the prediction parameters.
Among the indices, discriminating a first index having the highest coincidence, and calculating the predicted minute line segment calculated using the predicted parameter corresponding to the first index as a part of the shape of the target object And a definite minute line segment output means for outputting as the definite minute line segment representing the following. 2. A further determined minute line segment is obtained by setting one end of the determined minute line segment output by the determined minute line segment output unit as the further reference point in the predicted minute line segment calculating unit. The search radar according to claim 1, further comprising: an image forming unit configured to form an image of the shape of the target using the obtained sequence of the determined minute line segments when the processing is repeated. 3. The first index calculating means, wherein the observation point is i = 1, 2,..., N, the prediction time is τ, and the observation time is observed at each observation point i at the prediction time τ. Assuming that the amplitude value is s _i (τ) and the predicted amplitude value obtained from each observation point i at the predicted time τ is u _i (τ), as the first index, 3. The method according to claim 1, wherein the confirmed minute line segment output unit determines that the coincidence between the observed amplitude value and the predicted amplitude value is the highest when the first index is minimum. 4. Exploration radar. 4. An exploration radar for exploring the target by transmitting an exploration wave toward an inside of an exploration area and observing a reflected wave reflected by the target at a plurality of observation points, A predicted minute line segment calculating means for calculating a predicted minute line segment using an arbitrary prediction parameter, using one end of the already determined confirmed minute line segment representing a part of the shape as a reference point, Prediction time calculation means for calculating a prediction time required for the search wave to reciprocate between the observation point and the prediction time, and using the prediction time, when the search wave is reflected by the prediction minute line segment, Predicted amplitude value calculation means for calculating an amplitude value predicted to be observed at a point as a predicted amplitude value, and when the reception time from the transmission start time of the exploration wave is replaced with the corresponding predicted time, the predicted time To Observation amplitude value output means for outputting an amplitude value of the received reflected wave as an observation amplitude value, and the predicted amplitude value obtained by multiplying the observation amplitude value and any matching parameter obtained using the prediction parameter When,
A second index calculating means for calculating a second index indicating the coincidence of the second parameter; and the second index calculated for a plurality of the prediction parameters.
And discriminating a second index indicating the highest coincidence from the indexes, and outputting the predicted minute line segment calculated using the prediction parameter corresponding to the second index as a provisional minute line segment. Provisional minute line segment output means, and the provisional minute line segment output by the provisional minute line segment output means is used as the further reference point in the predicted minute line segment calculation means to further provide the provisional minute line. When the process of obtaining the minute is repeated, a provisional amplitude value sequence output means for outputting the sequence of the predicted amplitude values corresponding to the obtained sequence of the provisional minute line segments as a provisional amplitude value sequence; Third index calculating means for calculating a third index indicating a match between a sequence of wave amplitude values and the provisional amplitude value sequence obtained using the matching parameters; Calculated for The third
Among the indices, the third index indicating the highest coincidence is discriminated, and the series of the provisional minute line segments calculated using the matching parameter corresponding to the third index is converted into the shape of the target object. And a definite minute line segment sequence output means for outputting as a definite minute line sequence representing the following. 5. The exploration radar according to claim 4, further comprising image forming means for forming an image of the shape of the target using the determined minute line sequence output by the determined minute line sequence output means. . 6. The second index calculating means, wherein the observation point is i = 1, 2,..., N, the predicted time is τ, and the observation time is observed at each observation point i at the predicted time τ. When the amplitude value is s _i (τ), the predicted time value τ is the predicted amplitude value obtained from each of the observation points i at u _i (τ), and the matching parameter is ρ, as the second index, Equation 2 The tentative minute line segment output unit determines that the coincidence between the observed amplitude value and the predicted amplitude value is the highest when the first index is minimum, according to claim 4 or 5, Exploration radar. 7. The third index calculating means sets the observation point to i = 1, 2,..., N, and sets an observation time at which the reflected wave can be observed at each observation point i to T _i , The sequence of the observed amplitude values over the observation time is represented by S _i (t),
When the provisional amplitude value sequence is U _i (t), the third
As an index of The confirmed minute line segment sequence output means, when the second index is minimum, the highest consistency between the received sequence of amplitude values of the reflected wave and the provisional reflection amplitude value sequence The exploration radar according to claim 6, wherein: 8. The predictive amplitude value calculating means, wherein the distance that the probe wave reciprocates between the observation point and the predicted minute line segment is l, the attenuation rate of the probe wave in the ground is λ, the target The reflection coefficient of the object is γ, the function representing the directivity of the transmitting antenna of the search radar is g _T , the function representing the directivity of the receive antenna of the search radar is g _R , the directivity of the target reflecting the search wave. When the function representing the characteristic is g _P ,
As the predicted amplitude value, The search radar according to any one of claims 1 to 7, which calculates 9. The search radar according to claim 1, wherein a reflection point on the predicted minute line segment of the search wave is set at a midpoint between the reference point and the predicted point. 10. An exploration method for exploring the target at a plurality of observation points by transmitting an exploration wave toward an exploration area and observing a reflected wave reflected by the target, A first step of calculating a predicted minute line segment using an arbitrary prediction parameter using one end of a determined minute line segment that has already been determined and representing a part of the shape, and calculating the predicted minute line segment and the observation point A second step of calculating a predicted time required for the exploration wave to reciprocate between and, using the predicted time, when the exploration wave is reflected at the predicted minute line segment, at the observation point A third step of calculating an amplitude value predicted to be observed as a predicted amplitude value; and, when a reception time from the transmission start time of the exploration wave is replaced with a corresponding prediction time, the reception time is calculated at the prediction time. A fourth step of outputting the amplitude value of the reflected wave as the observed amplitude value, and calculating a first index indicating the consistency between the observed amplitude value and the predicted amplitude value obtained using the prediction parameter. A fifth step; and the first step calculated for a plurality of the prediction parameters.
Among the indices, discriminating a first index having the highest coincidence, and calculating the predicted minute line segment calculated using the predicted parameter corresponding to the first index as a part of the shape of the target object A sixth step of outputting as the determined minute line segment representing the following. 11. A process for obtaining a further determined minute line segment by using one end of the determined minute line segment output in the sixth step as the further reference point in the first step is repeated. The search method according to claim 10, further comprising a seventh step of forming an image of the shape of the target object using the obtained series of the determined minute line segments. 12. The fifth step comprises the following steps: i = 1, 2,..., N for the observation point, τ for the prediction time, and the observation amplitude value observed at each observation point i at the prediction time τ. S
_i (τ), when the predicted amplitude value obtained from each observation point i at the predicted time τ is u _i (τ), the first
As an index of The exploration method according to claim 10 or 11, wherein the sixth step determines that the coincidence between the observed amplitude value and the predicted amplitude value is the highest when the first index is the minimum. . 13. An exploration method for exploring the target by transmitting an exploration wave toward an exploration area and observing a reflected wave reflected by the target at a plurality of observation points, wherein: An eighth step of calculating a predicted minute line segment using an arbitrary prediction parameter using one end of a determined minute line segment that has already been determined and representing a part of the shape, and calculating the predicted minute line segment and the observation point A ninth step of calculating a predicted time required for the search wave to reciprocate between and, using the predicted time, when the search wave is reflected by the predicted minute line segment, at the observation point A tenth step of calculating an amplitude value predicted to be observed as a predicted amplitude value, and when the reception time from the transmission start time of the search wave is replaced with the corresponding prediction time, reception at the prediction time is performed. Wherein an eleventh step of outputting the amplitude value of the reflected wave as observed amplitude values, the obtained with the prediction parameters, said prediction amplitude values obtained by multiplying the observed amplitude and arbitrary matching parameters,
A twelfth step of calculating a second index indicating a match between the second parameter and the second parameter calculated for a plurality of the prediction parameters.
And discriminating a second index indicating the highest coincidence from the indexes, and outputting the predicted minute line segment calculated using the prediction parameter corresponding to the second index as a provisional minute line segment. A thirteenth step and a process of obtaining a further provisional minute line segment by using one end of the provisional minute line segment output in the thirteenth step as the further reference point in the eighth step; A 14th step of outputting a sequence of the predicted amplitude values corresponding to the obtained sequence of the provisional minute line segment as a provisional amplitude value sequence, and a sequence of the amplitude values of the received reflected waves; A fifteenth step of calculating a third index indicating a match between the provisional amplitude value sequence obtained using the matching parameters and the third index calculated for a plurality of the matching parameters;
Among the indices, the third index indicating the highest coincidence is discriminated, and the series of the provisional minute line segments calculated using the matching parameter corresponding to the third index is converted into the shape of the target object. Output as a series of determined minute line segments representing
An exploration method comprising the steps of: 14. The apparatus according to claim 1, further comprising a seventeenth step of forming an image of the shape of the target object using the sequence of the determined minute line segments output in the sixteenth step.
3. The exploration method according to 3. 15. The twelfth step comprises the steps of: i = 1, 2,..., N, the observation time, the prediction time τ, and the observation amplitude value observed at each observation point i at the prediction time τ. Where s _i (τ), the predicted amplitude value obtained from each observation point i at the predicted time τ is u _i (τ), and the matching parameter is ρ, as the second index, ] The search method according to claim 13 or 14, wherein the thirteenth step determines that the coincidence between the observed amplitude value and the predicted amplitude value is the highest when the first index is minimum. . 16. The fifteenth step is that the observation points are i = 1, 2,..., N, the observation time at which the reflected wave can be observed at each observation point i is T _i , and the observation time is Is a sequence of the observed amplitude values over S _i (t),
When the provisional amplitude value sequence is U _i (t), the third
As an index of The sixteenth step determines that when the second index is the minimum, the consistency between the received sequence of amplitude values of the reflected wave and the provisional reflection amplitude value sequence is the highest. Claim 1
5. The exploration method according to 5. 17. The method according to claim 17, wherein the third step and the tenth step are performed by setting a distance that the search wave reciprocates between the observation point and the predicted minute line segment to 1, and an attenuation rate of the search wave in the ground. Λ, the reflection coefficient of the target object is γ, a function representing the directivity of the search wave transmitting antenna is g _T , a function representing the directivity of the search wave receiving antenna is g _R , and the search wave is reflected. A function representing the directional characteristic of the target is g
_{When P} is used, the predicted amplitude value is given by: The exploration method according to any one of claims 13 to 16, which calculates 18. The search method according to claim 13, wherein a reflection point on the predicted minute line segment of the search wave is set at a midpoint between the reference point and the predicted point.