JPH04315082A - Object locating method - Google Patents

Abstract

PURPOSE:To obtain equivalent direction resolution by connecting each wave reception array and receiving wave with a hypothetical long array even when a ship carrying the array is rolling and is unable to move on a straight line. CONSTITUTION:To realize a higher resolution than one obtained with the length of an array 2, a system is constituted of an input/output device 5 to transfer the data from each wave accepter on the array 2 to a data signal processing device 4 a memory device to store the output data, a central processing unit(CPU) 6, a position detector 10 to detect the position of a ship and an indicator 9 to indicate the results of the calculation. Therefore, even in the case the ship carrying the array is rolling and is unable to move on a straight line, a direction resolution equivalent to connecting each reception array and receiving with a hypothetical long array can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the direction of arrival of sound waves, electromagnetic waves, etc., and more particularly to a method for detecting the position of an object suitable for obtaining high azimuth resolution during wave reception.

0002

2. Description of the Related Art As a conventional object position detecting device, a synthetic aperture radar that achieves high azimuth resolution has been put into practical use. In addition, in the field of sonar, a method using the synthetic aperture method is described in J.A.S.A. Vol. 54, No. 3 (1973), Paragraphs 799 to 802 (The Journal o
f Acoustical Society of A
merica Vol. 54 No. 3 (1973) p.
p799-802). This uses the same principle as synthetic aperture radar; in order to detect the position of an object, an array of sensors of a predetermined length must be accurately moved in a straight line.

0003

[Problem to be solved by the invention] In the conventional synthetic aperture method, it is necessary to move the array accurately in a straight line, but in the case of underwater sonar, because the ship shakes due to the influence of waves, etc., it is necessary to move the array accurately in a straight line. I couldn't move it.

The first object of the present invention is to receive waves with a virtual array length that is approximately equivalent to the distance traveled by the array, even if the array in which the sensors are lined up moves away from the straight line. The object of the present invention is to provide a method for detecting the position of an object that achieves a similar azimuth resolution.

[0005] The second object of the present invention is that even if the array in which the sensors are lined up moves away from the straight line, the result of receiving waves in a virtual array whose length is approximately equivalent to the distance the array has moved is An object of the present invention is to provide a method for detecting the position of an object that achieves azimuth resolution similar to that of the present invention.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the object position detection method of the present invention includes mounting an array of a predetermined length in which transducers are arranged on a moving body, and moving the array. In the method of detecting an object by repeatedly transmitting and receiving waves, and receiving the reflected waves from the object, the receiving array is moved so as to overlap a part of the previous receiving array, and its receiving position is is obtained from a position detection device mounted on a mobile object, the corresponding overlap range is determined, the spectrum is calculated from the received signal of each overlap part, the phase difference between the arrays is determined from the spectrum, and finally the received signal is The spectrum obtained in the non-overlapping part is corrected by multiplying it by the phase difference, and the spectrum obtained by receiving the wave at the previous array is
The object position detection method is characterized in that the object is visualized with high resolution by adding the corrected spectra.

Furthermore, an array of a predetermined length in which transducers are arranged is mounted on a moving object, and the array is moved to repeatedly send and receive waves, and receives the reflected waves from the object. In this method, the wave receiving array is moved so as to overlap a part of the previous wave receiving array, and the corresponding overlap range is determined by obtaining the wave receiving position from a position detection device mounted on the moving body. A spectrum is calculated from the received signal in the overlapped area, the phase difference between the arrays is determined from the spectrum, and the spectrum obtained in the non-overlapping area received last time is multiplied by the phase difference to correct it. The object position detection method is characterized in that the object is visualized with high resolution by adding this corrected spectrum to the spectrum obtained by receiving the wave at the last received array.

[0008] Furthermore, in a method of detecting an object by mounting an array of transducers of a predetermined length on a moving body and receiving waves emitted from an object that can be considered to be stationary,
Move the receiving array so that it overlaps a part of the previous receiving array, obtain the receiving position from a position detection device mounted on the moving body, find the corresponding overlap range, and calculate the receiving signal of each overlapped area. Calculate the spectrum from , find the phase difference between the arrays from that spectrum, multiply the spectrum found in the last non-overlapping area received by the phase difference to correct it, and then calculate the phase difference between the arrays. The object position detection method is characterized in that the object is visualized with high resolution by adding the corrected spectrum to the obtained spectrum.

[0009] Furthermore, in a method of detecting an object by mounting an array of transducers of a predetermined length on a moving body and receiving waves emitted from an object that can be considered to be stationary,
The wave receiving array is moved so that it overlaps a part of the previous wave receiving array, and the wave receiving position is obtained from a position detection device mounted on the moving object to determine the corresponding overlap range, and the wave receiving array of each overlapped area is determined. Calculate the spectrum from the signal, find the phase difference between the arrays from that spectrum, multiply the spectrum found in the non-overlapping area received last time by the phase difference to correct it, and then calculate the phase difference in the last received array. The object position detection method is characterized in that the object is visualized with high resolution by adding this corrected spectrum to the spectrum obtained by receiving the wave.

Furthermore, when transmitting a burst sine wave of a certain frequency is repeated two or more times, the received signal of the array that received the reflected wave first and the part of the array that receives the reflected wave from the second time onwards are different from the previous one. Overlap with the array to receive reflected waves,
In an object position detection method for detecting direction and distance,
A signal processing device including a storage device that takes in the received signal and stores the signal and the position of the array, and a central processing unit that processes the signal, and input/output between the received signal and the signal processing device. The signal processing device stores the signals received by the array, and then overlaps a part of the array to display the signal. The device is characterized by having a means for storing signals received after moving the moving body at least once and position information from a position detection device, and repeating these movements, transmitting waves, and receiving waves to improve resolution. shall be.

Furthermore, in a method for detecting the position of an object in which the direction and distance are detected by repeatedly transmitting a burst sine wave of a certain frequency twice or more, the received signal is captured and the signal and the position of the array are memorized. a signal processing device comprising a storage device for processing the signal and a central processing unit for processing the signal;
It consists of an input/output device that inputs and outputs the received signal to and from the signal processing device, and a display device that displays the result of signal processing, and the signal processing device stores the signal received by the array. Then, after moving the movable body at least once, the received signal and the position information from the position detection device are stored, and these movements, wave transmissions, and wave receptions are repeated to improve the resolution. It is characterized by having

0012

[Operation] In the present invention, an array fixedly mounted on a moving object repeatedly transmits sound waves while the moving object is moving, and receives reflected waves from objects in the direction. However, reception is performed by partially overlapping the previous array. The wave reception position is determined from devices such as a speedometer and a gyroscope. At this time, the phase difference between the arrays is determined from the spatial spectrum of the overlap, the spatial spectrum of the non-overlapping part is multiplied by this phase difference to correct it, and it is added to the spatial spectrum obtained from the previous array to obtain high resolution. get. In addition, the phase difference obtained in the overlap section is multiplied by the spatial spectrum obtained in the previous array to correct it.
It may be added to the spatial spectrum obtained in the last array.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 7. In the present invention, as shown in FIG. 1, an array of receivers having a predetermined length u is mounted on a moving body such as a ship, and a burst sine wave of a certain frequency is transmitted multiple times. In the method of visualizing an object by receiving the reflected waves, the processing results of each received wave data can be superimposed on the display screen of the output device, and as a result, the object can be displayed with high resolution. has been done.

[0014] Then, an array of a predetermined length u in which the receivers are arranged is mounted on a moving body, and a storage device that captures the received signal, stores this signal, and a central processing unit (CPU) that processes the signal. The signal processing device includes a signal processing device, an input/output device that inputs and outputs received signals to and from the signal processing device, and a display device that displays the results of signal processing.

FIG. 1 is a block diagram of the entire apparatus for implementing the method of the present invention. In the present invention, in order to achieve a resolution higher than that obtained by the array length, the input/output device 5 transfers the data of the output of each receiver on the array to the signal processing device 4, and the storage device stores the output data. , a central processing unit (CPU) 6 that performs calculations such as spectra, a position detection device 10 that detects the position of the ship, and a display device 9 that displays the calculation results.

The principle of this method will be explained. Assume that an array of length L in which elements are arranged for every half wavelength first receives waves at a position P1 on the coordinates shown in FIG. 2, and then the same array moves to a position P2. Here, P1
The waves received at P2 are assumed to be array A, those received at P2 are assumed to be array B, and the overlapped portions are assumed to be OA and OB, respectively. Let C be a hypothetical long array that includes array A. Further, it is assumed that the same sound waves are received at P1 and P2. The range of OA and OB in the overlap portion can be determined by a position detection device. Since the same sound waves are received in this overlapped portion, it is considered that the difference here is mostly a phase difference corresponding to the distance m between the two arrays. Furthermore, this phase difference relationship can also be applied to the relationship between arrays A and B. Because array A and array B
This is because they receive the same sound waves. The feature of this method is that the phase difference obtained between OA and OB is corrected by this phase difference against the image information (spatial spectrum) created in the non-overlapping part of array B, and it is stopped at array A. Add to image information. In this way, the data of array A and the image information obtained by array B are corrected to create the same image information as the data received by long array C.

If the direction of the sound wave is θ, the receiving position is x, and its function is f(x), X=sinθ, then the image created from f(x) can be Fourier transformed.

[
0018

[Math 1]

[0019] Here, the information on the image plane of OB is

[
0020

[Math 2]

The integral on the right side of equation (2) is the image information itself obtained by OA. Therefore, the correction amount exp(-m/λ) of array B can be determined from the images of OA and OB. If the non-overlapping portion of array B is multiplied by this correction amount and added, an image equivalent to that obtained with array C will be obtained. This is because the image information obtained by array C can be written as follows.

[0022]

[Math 3]

The first term on the right side of equation (3) is information obtained from array A, and the second term is information obtained by correcting array B.

A specific example of the above operation will be given below.

Assume that sound waves are uniformly arriving from a certain range of directions. In this case, if the wave is received by array A and the amplitude and phase are observed, the result will be as shown in FIG. In FIG. 3, the upper part shows the amplitude, and the lower part shows the phase. Similarly, the received signal at array B is shown in FIG. Since array B is located in front of array A, it can be seen from these two figures that a phase difference occurs accordingly. A diagram of the amplitude and phase of the received signal obtained by array C is shown in FIG.

Next, this phase difference is determined from the overlapping portion. OA image information Fa(X), OB
If the image information of is Fb(x), then Equation (4) and Equation (5)
It can be written as Using these, the phase difference ψ can be calculated using the formula (
6).

[0027]

[Math 4]

[0028]

[Math 5]

[0029]

[Math 6]

The phase difference ψ obtained in this way is
By multiplying the non-overlapping part of , the result is as shown in FIG. If FIG. 3 and FIG. 6 are added, FIG. 7 is obtained. Comparing FIG. 7 and FIG. 5 obtained in this way, it can be seen that there is almost no difference and correct beamforming is performed.

In this operation, there are several methods for detecting the phase difference. For example, the definition of phase is -1
Assume that the angle is from 80 degrees to +180 degrees. At this time, it is assumed that the result of calculating the phase difference ψ is around +180 degrees. At this time, there is a possibility that phase data wrap-around occurs. In other words, a value that should normally be calculated as +190 degrees is instead calculated as -170 degrees. To avoid such a phenomenon, +1
When the value is close to 80 degrees, the phase definition is changed, that is, from 0 degrees to 360 degrees, and the calculation is performed again. By using such a procedure, it is possible to prevent the phase data from collapsing.

On the other hand, as a method for detecting the receiving position,
There are the following methods.

(1) Method using only the accelerometer mounted on the moving body By integrating the information from the accelerometer twice, the distance traveled can be determined. Therefore, by calculating the moving distance based on the position where wave transmission is started, the wave transmission and wave reception positions can be determined.

(2) Method using only the speedometer mounted on the moving body By integrating the information from the speedometer, the distance traveled can be determined. Therefore, by calculating the moving distance based on the position where wave transmission is started, the wave transmission and wave reception positions can be determined.

(3) Method using a speedometer and gyroscope mounted on a moving body By integrating the information from the speedometer, the distance traveled can be determined. Furthermore, by using a gyroscope, the attitude of a moving object can be determined. Therefore, if the moving distance is calculated based on the position where the wave transmission started, the wave transmission and wave reception positions can be determined from the accelerometer information and the gyroscope information.

(4) Method using an accelerometer and gyroscope mounted on a moving body By integrating the information from the accelerometer twice, the distance traveled can be determined. Furthermore, by using a gyroscope, the attitude of a moving object can be determined. Therefore, if the moving distance is calculated based on the position where the wave transmission started, the wave transmission and wave reception positions can be determined from the accelerometer information and the gyroscope information.

(5) GPS (Global Position)
Methods (1) to (3) of obtaining the position of a moving object by monitoring it from a satellite such as the ioning system are position detection methods using inertial navigation, but it is also possible to determine the position using satellite navigation. . For example, there is a method in which a mobile body is constantly monitored from a plurality of satellites and the position information of the mobile body is provided to the mobile body.

When obtaining the current position of a moving object using the methods (1) to (4), it may be an absolute position or a relative position from the position where wave transmission was first started.

Although the case of a sonar mounted on a ship has been described above, the same can be said for the case of a radar mounted on a flying object.

[0040]

[Effects of the Invention] According to the present invention, even when a ship equipped with an array cannot move in an accurate straight line and the synthetic aperture method cannot be used, high resolution can be achieved using information from the position detection device and the isochronous convergence method. images of objects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing wave receiving positions.

FIG. 3 is a waveform diagram when waves are received by array A and beamforming is performed.

FIG. 4 is a waveform diagram when waves are received by array B and beamforming is performed.

FIG. 5 is a waveform diagram when waves are received by array C and beamforming is performed.

FIG. 6 is a waveform diagram in which a phase difference is corrected by receiving waves in a non-overlapping portion of array B and performing beam forming.

FIG. 7 is a high-resolution waveform diagram obtained by the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Mobile body, 2... Array, 3... Receiver, 4... Signal processing device, 5... Input/output device, 6... Central processing unit, 7... Image memory, 8... ROM, 9... RAM, 10... Display device , 11...
Position detection device.

Claims (1)

[Claims] Claim 1: An array of a predetermined length in which transducers are arranged is mounted on a moving body, and the array is moved to repeatedly transmit and receive waves, and to detect reflections from an object that can be considered stationary. In a method of detecting objects by receiving waves, the wave receiving array is moved so as to overlap a part of the previous wave receiving array, and the wave receiving position is obtained from a position detection device mounted on a moving body. calculate the spectrum from the received signal of each overlapped part, calculate the phase difference between the arrays from the spectrum, and calculate the spectrum for the spectrum obtained in the last received non-overlapping part. A method for detecting the position of an object, characterized in that the corrected spectrum is multiplied by a phase difference, and the corrected spectrum is added to the spectrum obtained by the previous wave received by the array.