JP2528973B2 - Underwater detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Use The present invention detects ultrasonic waves transmitted in a wide range of directions in water and reflected waves returning from each direction for each returning direction. The present invention relates to a device for detecting an underwater object, and more particularly to a device for detecting the arrival direction of a reflected wave of the seabed with high accuracy.

(B) Conventional Technology When forming a directional beam in an underwater detector, generally, after phase control of the received signal of each transducer of an ultrasonic transducer array in which a plurality of transducers are arranged in a straight line ,
By synthesizing the respective received signals, the received beam is formed by giving sensitivity only to the ultrasonic pulse incident from a specific one direction.

The phase control is performed by delaying the received signal by a phase equivalent time. Therefore, the delay time is determined by the underwater wavelength of the ultrasonic signal. When the frequency of the underwater wavelength of the ultrasonic signal is constant, it changes depending on the underwater sound velocity of the ultrasonic wave, and the underwater sound wave changes depending on the water temperature. Therefore, when the actual water temperature is different from the predetermined design temperature, the receiving beam formed in the water is formed in a direction slightly different from the design (calculation) pointing direction.

In order to solve such a problem, the underwater detection apparatus is configured to correct the arrival direction of the received signal in consideration of the actual water temperature and the designed water temperature, that is, the difference between the actual sound velocity and the designed sound velocity. The present applicant has disclosed an invention relating to
I am applying for No. 78.

(C) Problem to be Solved by the Invention However, the deviation of the direction of the received beam due to the difference between the design sound velocity and the actual sound velocity, that is, the sound ray refraction does not always occur only on the surface of the receiver. In general, the temperature of water shows a distribution in the depth direction, and the speed of sound changes not only by the water temperature but also by the pressure and the salinity concentration, and these show the distribution in the depth direction. Figure 10 shows a typical example of the change in sound velocity at each depth. At a water depth of 0 to 1000 m, the pressure increases as it gets deeper, but since the effect of lowering the water temperature is great, the sound velocity decreases as it gets deeper. Since the temperature is almost constant at a depth greater than about 1000 m, the sound speed increases with increasing pressure as the depth increases. In general, when performing seafloor exploration in a relatively deep sea area, sound ray refraction due to temperature changes in the depth range of 0 to 1000 m becomes large, and the surface temperature around the receiver is used as water temperature information. Even if the ray refraction on the surface of the vessel is corrected, the effect of the ray refraction in the middle remains.

Design (calculation) for deep seafloor exploration
Figure 11 shows an example of the received beam and the actual received beam. First
In Fig. 11, θa is the calculated directivity angle of the received beam, θ
b is the directivity angle of the equivalent received beam, and the broken line represents the actual sound ray. In such a case, it is considered that the reflected wave arrives from the point b in the direction of the angle θa, and thus it is considered that the object (sea bottom) at the point b exists at the point a.
In this way, the error in the pointing direction appears as the horizontal and vertical distance error of the detected object (seabed). When the seabed topographic map is created using the seabed signal with such distance error, the actual topography is A topographic map with a distortion different from that of the map is created.

To find the exact sound ray from the receiver to the detected object,
Usually, Snell's law is used to continuously calculate the refraction state of the sound ray at each minute water depth, and the propagation path of all sound waves may be obtained.
However, if this calculation is officially performed, a large amount of calculation is required. Therefore, if detection is performed every time a wave is transmitted or received in another direction, it cannot be processed in real time. After that, it must be performed as a post-treatment.

Further, since the wave receiver is usually mounted on the bottom of the ship, the actual direction of the received beam changes due to rolling of the ship as shown in FIG. Therefore, conventionally, the rolling angle is detected by using a vertical gyro, etc., and the actual pointing direction is obtained by correction, but the sound on the receiver surface due to the difference between the sound velocity on the receiver surface and the design sound velocity is corrected. Since there is line refraction, there is a problem that an error occurs in the rolling angle correction itself.

The object of the present invention is to enable real-time correction including the sound ray refraction from the detection object to the wave receiver, and to obtain detection information without graphic distortion due to sound ray refraction at the same time as transmission and reception of ultrasonic pulses. An object of the present invention is to provide an underwater detection device.

Another object of the present invention is to provide an underwater detection apparatus that corrects the received beam directivity angle due to the inclination of the wave receiver due to rolling of a ship or the like and eliminates the influence thereof.

(D) Means for Solving the Problem An underwater detection apparatus according to claim 1 of the present invention is an ultrasonic wave transmitting means for transmitting an ultrasonic pulse, and an ultrasonic wave receiving means for receiving a reflected wave of the transmitted ultrasonic pulse. When a receiver composed of an ultrasonic transducer array is used to synthesize the phases of the received signals of the transducers of this ultrasonic transducer array, the time difference at the design sound velocity is oscillated according to the designed receiving direction. In addition to giving the received signal of each transducer in the order of child arrangement,
Ultrasonic receiving means for synthesizing these received signals to obtain a received signal from the designed receiving direction, and the time from the transmission of the ultrasonic pulse to the reception of the reflected wave and the above The average sound velocity from the sensing object that reflected the ultrasonic pulse to the wave receiver or the design sound velocity determines the distance from the sensing object that reflected the ultrasonic pulse to the wave receiver, and this distance and the receiving In the underwater detection apparatus including a depth measuring unit that determines the depth of the detection object from the direction of the wave from the wave detector to the detection object, the water temperature at the water depth from the wave receiver to the detection object to which the ultrasonic pulse is reflected Average sound velocity setting means for reading the distribution data and obtaining the average sound velocity from the wave receiver to the detection object based on the water temperature distribution, or for reading the average sound velocity directly input from the outside. , The average speed of sound Ca, the design sound velocity Cd, when the reception directivity direction θ0 of the above ^{design, θ2 = sin -1 {(Ca} / Cd) sinθ0} equivalently reception expressed in relation Means for determining the pointing direction (θ2) as the pointing direction when the depth measuring means determines the depth.

An underwater detection apparatus according to claim 2 uses an ultrasonic wave transmitting means for transmitting an ultrasonic wave pulse, and a wave receiver including an ultrasonic wave transducer array for receiving a reflected wave of the transmitted ultrasonic wave pulse, When the received signals of each transducer of this ultrasonic transducer array are phase-synthesized, the received signal of each transducer is given a time difference in the design sound velocity in accordance with the designed receiving direction of the transducer. With
Ultrasonic receiving means for synthesizing these received signals to obtain a received signal from the designed receiving direction, and the time from the transmission of the ultrasonic pulse to the reception of the reflected wave and the above The average sound velocity from the sensing object that reflected the ultrasonic pulse to the wave receiver or the design sound velocity determines the distance from the sensing object that reflected the ultrasonic pulse to the wave receiver, and this distance and the receiving In the underwater detection device including a depth measuring means for obtaining the depth of the detection object from the direction of the wave from the wave detector to the detection object, the water temperature data on the surface of the wave receiver is read, and based on the water temperature data, From the wave receiver surface sound velocity setting means for obtaining the wave velocity of the wave receiver surface or directly reading the sound velocity of the wave receiver surface directly input from the outside, to the detection object from which the ultrasonic pulse is reflected An average sound velocity setting means for reading the data of the water temperature distribution in the water depth, obtaining the average sound velocity from the wave receiver to the detection object based on this water temperature distribution, or reading the average sound velocity directly input from the outside, When the sound velocity on the surface of the receiver is Cs, the design sound velocity is Cd, and the wave receiving direction in the design is θ0, the reception is expressed by the relationship of θ1 ′ = sin ⁻¹ {(Cs / Cd) sin θ0}. Means for obtaining the wave receiving direction (θ1 ′) after the refraction angle correction on the wave receiver surface, and wave receiver tilt angle for detecting the tilt angle (θr) of the wave receiver itself in the changing direction of the wave receiving direction. The detection means and the wave receiver itself by adding or subtracting the inclination angle (θr) of the wave receiver itself with respect to the wave receiving direction after correction of the refraction angle on the surface of the wave receiver (θ1 ′). Cancels changes in the receiving direction due to tilt angle changes Means for obtaining the wave-receiving direction after the tilt angle correction on the surface of the wave receiver, Ca for the average sound speed, Cs for the sound speed on the surface of the wave receiver, and θ1 for the wave-receiving direction after the tilt angle correction. Then, the equivalent wave receiving directivity (θ2) represented by the relationship of θ2 = sin ⁻¹ {(Ca / Cs) sin θ1} is obtained as the directivity when the depth measuring means obtains the depth. Is provided.

(E) Action The configuration of the underwater detection apparatus according to claim 1 of the present invention is
Shown in the figure.

In FIG. 1, reference numeral 1 is a receiver including an ultrasonic transducer array that receives a reflected wave of the transmitted ultrasonic pulse.
The receiving beam directing direction control means 2 synthesizes the receiving signals of the transducers of the ultrasonic transducer array to form a receiving beam directed in one direction, and sequentially changes the pointing direction.
Reference numeral 3 is a means for giving an average sound velocity in the detection depth range. For example, using a water temperature meter of the throwing type, the temperature distribution in the depth direction is measured, and the underwater sound velocity at the average temperature in the detection depth range is obtained. It is given to the correction means 4. The sound ray refraction correcting unit 4 corrects the pointing direction of the received beam by the amount of sound ray refraction from the detection object to the wave receiver according to the ratio of the design sound velocity to the average sound velocity. The relationship between each sound velocity and the ray refraction is shown in FIG. In FIG. 3 (A), θo is the designed directivity angle of the received beam, θ2 is the equivalent directivity angle of the received beam at the average sound velocity, and the sound ray refraction correction means 4 sets the equivalent directivity angle θ2 to θ2. = Sin ^-1 {(Ca / Cd)
sin θo} can be obtained. For example, RO
It is written in M or the like as a table, and the actual directivity angle θ2 is calculated each time according to the current (designed) directivity angle θo of the receiving beam directivity direction control means 2, and θ2 is a necessary unit. If the received signal is sampled at every angle, the underwater detection information can be obtained at equal intervals for θ2.

FIG. 4 shows the relationship between the temporal change of the directivity angle of the received beam directivity control means 2 shown in FIG. 1 and the equivalent directivity angle. As shown by the solid line in FIG. 4, the designed incident angle θ
o repeats in a fixed cycle from -45 degrees to +45 degrees in proportion to the passage of time. For example, at the time to, the designed directivity direction is θo, but the equivalent directivity angle θ2 takes a slightly different value. The change in θ2 with the passage of time shows non-linearity as indicated by a broken line in the figure, for example.

According to a second aspect of the present invention, the underwater detection device has a second configuration.
Shown in the figure. In FIG. 2, reference numeral 5 is a means for giving the speed of sound on the surface of the wave receiver. For example, the temperature of the sea surface is measured and the underwater sound speed at that water temperature is given to the surface refraction angle correcting means 7. 6 is a means for detecting the inclination angle of the wave receiver in the in-plane direction of the fan-shaped region to be detected. The surface refraction angle correction means 7 corrects the directivity angle of the received beam on the surface of the wave receiver by the amount of the ray refraction corresponding to the ratio of the design sound speed to the sound speed of the ultrasonic pulse returning to the wave receiver to obtain θ1 ′. The tilt angle correction means 8 corrects the directivity angle θ1 ′ of the received beam on the surface of the wave receiver by the tilt angle θr of the wave receiver to obtain θ1. The average refraction angle correction means 9 corrects the ray refraction from the detection object to the wave receiver according to the ratio of the surface acoustic velocity Cs to the average acoustic velocity Ca, and obtains an equivalent pointing angle θ2.

FIG. 3 (B) shows the relationship between each sound velocity and the directivity angle.
In FIG. 3 (B), θo is the designed directivity angle of the received beam, θ1 is the actual directivity angle on the surface of the receiver, and θ2 is the equivalent directivity angle. Because of such a relationship, the surface refraction angle correction means 7 has θ1 ′ = sin ⁻¹ {(Cs / Cd) sin θ.
correction is performed from the relationship of o}. Further, the inclination angle correction means 8 subtracts or adds θr from the direction θ1 ′ of the sound ray on the surface of the wave receiver so as to cancel the inclination angle θr of the wave receiver as shown in FIG. Thus, the direction θ1 of the sound ray on the surface of the wave receiver when the wave receiver has no inclination is obtained. The average refraction angle correcting means 9 obtains the equivalent directivity angle θ2 from the relationship of θ2 = sin ⁻¹ {(Ca / Cs) sin θ1}.

(F) Embodiments FIGS. 6 and 7 show an example of equipment of ultrasonic wave transmitters and receivers provided in the underwater detection apparatus according to an embodiment of the present invention, and the state of detection by a cross fan beam by them. . Both the wave transmitter and the wave receiver shown in FIG. 6 consist of an ultrasonic transducer array, and the wave receiver has a fan shape with a predetermined angle (for example, 120 degrees) width in the left-right direction of the ship as shown in FIG. The transmission beam of is transmitted. The wave receiver forms a fan-shaped received beam that spreads in the front-back direction of the ship, and the echo at the portion where the two fan-shaped beams intersect (hatched portion in FIG. 7) is received.
By scanning the receiving beam in the left-right direction, the contour (submarine contour) of the seabed topography in the entire range (120 degrees) of the transmitting beam is obtained. In addition, dead reckoning operation is calculated from the ship's speed information and course information, the detection position of the seabed contour (latitude / longitude of the ship) is obtained, and three-dimensional information of the seabed topography is obtained by simultaneously performing bathymetry and positioning. .

FIG. 8 shows a block diagram of the control unit of the entire underwater detection apparatus. In FIG. 8, a control circuit 31 is a circuit for controlling transmission / reception of ultrasonic waves, and a transmission control circuit 32 sends to a driver circuit 33 in accordance with a trigger signal given from the control circuit 31 and a signal for controlling the directivity direction of a transmission beam. Give a transmit pulse. The driver circuit 33 supplies the output pulse to the output amplifier 34 separately for all channels. The output amplifier 34 drives the wave transmitter 35 and outputs the fan-shaped transmission beam in a predetermined directivity direction. The preamplifier 37 amplifies the output of each transducer of the wave receiver 36, and the beam former 38 performs phase control or the like on the output signal of the preamplifier 37 to create a received signal of a received beam to be directed. The pointing direction correction circuit 12 performs rolling correction based on the signal from the control circuit 31, and obtains the received signal in each pointing direction at the timing when the equivalent pointing angle becomes equal. The interface circuit 13 outputs the received signal as a video signal. The contour detection circuit 14 obtains the integrated center of the reflection intensity from the video signal of the received signal as the seabed depth data.

In the figure, reference numeral 15 is an arithmetic unit, and the interface circuit 16 receives the seabed depth data. The graphic circuit 17 creates three-dimensional graphic data of seafloor topography, contour line graphic data, vertical cross-section graphic data, horizontal cross-section graphic data and the like from a plurality of seabed depth data, and writes the graphic data to the RGB signal buffer 26. Reference numeral 18 denotes a system, which performs post-processing such as distance correction based on the average sound velocity described later. Video processing circuit
19 receives the video signal of the received signal.

The interface circuit 20 has an XY plotter 21 that draws a topographic map of the sea bottom, and a navigation device 2 that measures the current position of the ship.
2. An acoustic navigation device 23 for measuring the ship speed of the ship and a gyro compass 24 for measuring the heading of the ship are connected. The CRT 25 displays various graphic displays and images of received signals according to the display signals provided from the RGB signal buffer 26. The vertical gyro 11 is a device for detecting the rolling and pitching angles of the ship, and the signal conversion circuit 10 converts the rolling angle and the pitching angle into signals of a predetermined format and gives them to the control circuit 31. The water temperature sensor 40 measures the temperature of the seawater surface, and the signal conversion circuit 39 gives the sound velocity data at the water temperature to the directivity direction correction circuit 12. Average sound velocity input device
41 is a device for inputting the average sound velocity in the detection range,
For example, the average sound velocity is obtained from the measurement result of a throw-in type thermometer, and this is input manually. Of course, it may be automatically given from an automatic measuring device.

FIG. 9 shows a concrete configuration example from the wave receiver 36 shown in FIG. 8 to the directivity correction circuit 12. Receiver in FIG. 9
The received signals of the respective vibrators of 36 are amplified by the preamplifier 37 and then guided to the mixing circuit 56 provided corresponding to each of them. Each of the mixing circuits 56 individually mixes with the rectangular wave train read from the ROM 54. The rectangular wave train is generated by reading the data of the address corresponding to the count value when the counter 53 counts the clock pulses output from the frequency dividing circuit 51 that divides the pulse train of the clock pulse source 50. This rectangular wave train data is also latched by the latch pulse output from the latch pulse generation circuit 52.
Latched to 55.

The mixed output of the mixing circuit 56 is added by the adding circuit 57, and then the specific frequency component is extracted by the filter 58.
The received signal in the specific direction is amplified by the amplifier circuit 59, and the signal level that attenuates with the passage of time from the transmission timing of the ultrasonic pulse is corrected. The configuration up to this point is the same as the example of the receiving beam directivity control device shown in Japanese Patent Publication No. 1-16392 filed previously by the applicant.

In FIG. 9, a ROM 62 stores ROM table data for correcting the ray refraction component based on the ratio of the design sound velocity to the sound velocity on the surface of the receiver, and 63 rolls from the pointing direction θ1 ′ where the surface refraction angle is corrected. A circuit that corrects the inclination of the wave receiver by reducing the angle θr, and 64 stores in advance table data for correcting the ray refraction from the detection object to the wave receiver based on the ratio of the surface acoustic velocity to the average acoustic velocity. It is a ROM. With these circuits, the equivalent directivity angle θ2 is finally obtained with respect to the content θo of the counter 53 corresponding to the designed directivity angle.
Is required. The sampling pulse generation circuit 65 has an angle θ
2 is a circuit that generates a sampling pulse each time a certain unit angle is reached, and can be composed of, for example, a circuit that generates a fine clock pulse and a latch circuit.
The sample hold circuit 60 holds the output signal of the amplifier circuit 59 with a sampling pulse. A-D converter
61 converts this into digital data.

As described above, the detection information in which the direction of the received beam is corrected can be obtained. However, this information is not corrected in the distance direction due to the change in sound velocity. That is, the design sound velocity is fixed at 1500 m / sec, for example, and the distance is obtained from the time difference from the transmission timing to the reception timing.
If you want to correct the distance direction by the average sound velocity,
When the average sound velocity is Ca and the round-trip time of the ultrasonic pulse in the θ2 direction is T, the depth D can be obtained from the relationship of D = Tcos θ2 / 2Ca.

Although the above embodiment is an example corresponding to claim 2, when the inclination angle correction of the wave receiver is not considered, the output θo of the counter 53 and the average sound velocity shown in FIG. 9 are equivalent. Pre-store table data for obtaining the directivity angle θ2
The sound ray refraction can be corrected by ROM.

Further, in the above-described embodiment, the table data is written in the ROM in advance for use, but the table data is created by function calculation or the like when the power is turned on or when the data such as the average sound velocity or the average water temperature is fixed. ,this
It is also possible to store it in RAM and use it as a table.

(G) Effect of the Invention According to the invention of claim 1, since the sound ray from the detection object to the wave receiver is originally gradually refracted is approximated to be refracted at once by the wave receiver, the arithmetic processing is performed. It is greatly reduced, and the correction can be performed in real time.

According to the second aspect of the present invention, the direction of the sound ray on the surface of the wave receiver is rigorously determined, and the inclination angle of the wave receiver is corrected with respect to the incident angle of the received beam with respect to the wave receiver. In other words, the inclination angle of the receiver is not corrected in a state that includes the refraction due to the difference between the sound velocity on the surface of the receiver and the design sound velocity. Can be done accurately.

[Brief description of drawings]

FIG. 1 is a block diagram of claim 1 of the present invention, and FIG. 2 is a block diagram of claim 2. FIGS. 3 (A) and 3 (B) are views for explaining the state of ray refraction according to claims 1 and 2, and FIG. 4 is a design direction angle of the receiving beam direction control means. The figure which shows the time change of an equivalent pointing angle, 5th
The figure is a diagram showing the change of the received beam due to the inclination of the receiver. FIG. 6 and FIG. 7 are views showing an example of the equipment of the ultrasonic wave transmitter / receiver and the relationship between the transmitted and received beams. 8th
FIG. 9 is a block diagram of a control unit of an underwater detection apparatus according to an embodiment of the present invention, and FIG. 9 is a configuration diagram of its main part. FIG. 10 is a diagram showing an example of change in sound velocity at each depth. Furthermore
FIG. 11 is a diagram showing an example of sound ray refraction.

Claims (2)

(57) [Claims] 1. An ultrasonic transducer using ultrasonic wave transmitting means for transmitting an ultrasonic wave pulse, and a receiver comprising an ultrasonic wave transducer array for receiving a reflected wave of the transmitted ultrasonic wave pulse. When the received signals of the transducers in the array are phase-combined, the received signals of the transducers are given the time difference in the design sound velocity according to the designed receiving direction, and the received signals of the transducers are also added. Ultrasonic wave receiving means for synthesizing wave signals to obtain a received wave signal from the designed receiving direction, and time from the transmission of the ultrasonic wave pulse to reception of the reflected wave and the ultrasonic wave pulse By the average sound velocity or the design sound velocity from the detection object that reflected the to the receiver, while determining the distance from the detection object that reflected the ultrasonic pulse to the receiver, from this distance and the receiver From above the direction of pointing to the detected object In the underwater detection apparatus including a depth measuring unit for determining the depth of the detection object, the data of the water temperature distribution in the water depth from the wave receiver to the detection object where the ultrasonic pulse is reflected is read, and based on this water temperature distribution An average sound velocity setting means for obtaining the average sound velocity from the wave receiver to the detected object or reading the average sound velocity directly input from the outside, the average sound velocity Ca, the design sound velocity Cd, the design reception Assuming that the wave directing direction is θ0, the equivalent receiving directivity (θ2) represented by the relationship of θ2 = sin ⁻¹ {(Ca / Cd) sin θ0} is the directivity when the depth measuring means obtains the depth. An underwater detection device comprising: 2. An ultrasonic transducer using ultrasonic wave transmitting means for transmitting an ultrasonic wave pulse, and a receiver comprising an ultrasonic wave transducer array for receiving a reflected wave of the transmitted ultrasonic wave pulse. When the received signals of the transducers in the array are phase-combined, the received signals of the transducers are given the time difference in the design sound velocity according to the designed receiving direction, and the received signals of the transducers are also added. Ultrasonic wave receiving means for synthesizing wave signals to obtain a received wave signal from the designed receiving direction, and time from the transmission of the ultrasonic wave pulse to reception of the reflected wave and the ultrasonic wave pulse By the average sound velocity or the design sound velocity from the detection object that reflected the to the receiver, while determining the distance from the detection object that reflected the ultrasonic pulse to the receiver, from this distance and the receiver From above the direction of pointing to the detected object In an underwater detector equipped with depth measuring means for determining the depth of a detected object, the water temperature data on the surface of the wave receiver is read, and the speed of sound on the surface of the wave receiver is obtained based on this water temperature data, or from the outside. The receiver surface sound velocity setting means for reading the sound velocity of the surface of the receiver directly input, and the data of the water temperature distribution in the water depth from the receiver to the detection object where the ultrasonic pulse is reflected are read, Average sound velocity from the receiver to the detected object based on the distribution, or average sound velocity setting means for reading the average sound velocity directly input from the outside, and the sound velocity on the surface of the receiver is Cs, the design sound velocity the Cd, when the reception directivity direction θ0 of the above ^{design, θ1 '= sin -1 {(} Cs / Cd) sinθ0} reception directivity after refraction angle correction in receivers surface represented by the relationship Direction (θ1 ' Means for determining the inclination angle (θr) of the wave receiver itself in the direction in which the direction of the wave reception is changed, and wave reception after correction of the refraction angle on the surface of the wave receiver. By adding or subtracting the tilt angle (θr) of the wave receiver itself to the pointing direction (θ1 ′), the change in the wave receiving direction due to the change in the tilt angle of the wave receiver itself is canceled out, and the wave receiver is received. A means for obtaining the wave-receiving direction after the inclination angle is corrected, the average sound velocity is Ca, the sound velocity on the surface of the wave receiver is Cs, and the wave-receiving direction after the inclination angle is corrected is θ1, and θ2 = Underwater detection comprising means for obtaining an equivalent receiving direction (θ2) represented by the relationship of sin ^-1 {(Ca / Cs) sin θ1} as the direction of the depth when the depth measuring means obtains the depth. apparatus.