JPH0375832B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention involves reciprocating scanning of an ultrasonic transducer along a cross section perpendicular to the sea surface, emitting narrow beam ultrasonic waves to the seabed, and detecting the reflected waves. This invention relates to a scanning control device for a seafloor topography detection sonar that obtains seafloor cross-sectional shape data.

<Conventional technology> Conventionally, this type of device drives an ultrasonic transducer at a constant angular velocity, irradiates ultrasonic waves toward the seabed at regular intervals, and sends the reflected waves as appropriate along the depth direction. The cross-sectional shape of the ocean floor is detected by sampling. That is, as shown in Fig. 9, each time the ultrasonic transducer P is driven at a certain angle (θ shown in the figure), an ultrasonic beam is irradiated toward the seabed, and the reflected waves are emitted at a certain period. By sampling, detection data in the depth direction is obtained sequentially. By repeatedly collecting such data, the cross-sectional shape of the seafloor at the points irradiated with the ultrasonic beam (points 1 to 8 in the figure) can be sequentially observed.

<Problems to be Solved by the Invention> However, if the ultrasonic beam is irradiated every time the ultrasonic transducer P is driven at a fixed angle in this way, the distance between the beam irradiation points on the seabed (L shown in Fig. 9) ₁₂ to L ₇₈ ) spreads farther away from directly below the ultrasonic transducer P, so the seafloor topography can be accurately grasped near the area directly below the ultrasonic transducer P, but the seafloor topography becomes more difficult as you go further away. It becomes difficult to understand.

The present invention has been made in view of the above circumstances, and provides a scanning control device for a seafloor topography detection sonar that can accurately grasp the seafloor topography even at a point far away from directly beneath an ultrasonic transducer. The purpose is to

<Means for solving the problems> In order to achieve such an object, the present invention has the following features:
The configuration shown in FIG. 1 is adopted.

That is, the scanning control device 10 of the submarine topography detection sonar according to the present invention, which is shown surrounded by a chain line in the figure, includes a depth data output means 11 that provides data related to the depth of the seabed, and a depth data output means 11 that provides data related to the depth of the seabed. Reference pulse generating means 1 for generating reference pulses at a period determined based on depth data
2, and a reference pulse counting means 13 for counting the reference pulses given from the reference pulse generating means 12.
and an ultrasonic beam irradiation angle storage means 14 in which is written ultrasonic beam irradiation angle data such that ultrasonic beam irradiation points are equidistant with respect to a horizontal seabed.

Then, based on being given the count output of the reference pulse counting means 13, the ultrasonic beam irradiation angle storage means 14 stores the ultrasonic beam irradiation angle data written in the address corresponding to the count output. , to the ultrasonic beam irradiation means 20. As a result, the ultrasonic beam irradiation means 20
The ultrasound beam is scanned at an irradiation angle such that the ultrasound beam irradiation points are equally spaced.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 2 is a block diagram schematically showing the configuration of a submarine topography detection sonar using a control device according to an embodiment of the present invention.

In the figure, reference numeral 30 indicates an ultrasonic beam irradiation unit corresponding to the ultrasonic beam irradiation means 20 shown in FIG.
This is a scan control section corresponding to the .

In the ultrasonic beam irradiation unit 30, 31 is an ultrasonic transducer that emits ultrasonic waves of a predetermined frequency towards the seabed and detects the reflected waves.
The ultrasonic transducer 31 is driven by a motor 32 so as to swing on a cross section perpendicular to the sea surface.
The irradiation angle of the ultrasonic beam, that is, the ultrasonic transducer 3
The swing angle of 1 is detected by the potentiometer 33, and its detection signal is given as one input of the differential amplifier 34. Further, the differential amplifier 34 is supplied with an angle command voltage for commanding the irradiation angle of the ultrasonic beam from the scan control section 40 as the other input. The differential output of the differential amplifier 34 is connected to the motor 32
is applied to the drive circuit 35 of. Therefore, the above-mentioned ultrasonic vibrator 31, motor 32, potentiometer 33, differential amplifier 34 and vibration circuit 35
constitutes a servo system that controls the irradiation angle of the ultrasonic beam.

A part of the output of the differential amplifier 34 is given to an H→L detection circuit 36. The H→L detection circuit 36 detects a change in the output of the differential amplifier 34 (H→L). H
→The detection output of the L detection circuit 36 is given to the transmission trigger generation circuit 37. Transmission trigger generation circuit 37
receives the detection output, and outputs a transmission trigger for causing the ultrasonic transducer 31 to irradiate an ultrasonic beam.

On the other hand, in the scan control section 40, the range setting device 41 is connected to the depth data output means 11 shown in FIG.
The depth range is set appropriately depending on the depth of the seabed to be detected. In this embodiment, for example, depth ranges of 12.5 m, 25 m, and 50 m are provided. The output of the range setter 41 is given to a reference pulse generation circuit 42. The reference pulse generation circuit 42 corresponds to the reference pulse generation means 12 shown in FIG. The period of this reference pulse is determined in accordance with the time it takes for the ultrasonic beam irradiated from the ultrasonic transducer 31 toward the ocean floor at the farthest point to be reflected on the ocean floor and return.
In this example, when the depth range is 12.5 m, 18
msec, 37msec on 25m range, 55m on 50m range
sec respectively. The output of the reference pulse generation circuit 42 is applied to a counter 43 as the reference pulse counting means 13 shown in FIG.
The count output of the counter 43 is given to the table ROM 44 as address data.

The table ROM 44 corresponds to the harmonic beam irradiation angle storage means 14 shown in FIG.
The ultrasonic beam irradiation angle data is written so that the ultrasonic beam irradiation points are equidistant with respect to the horizontal seabed. The arrangement of angle data in the table will be specifically explained below. As shown in FIG. 3, the depth of the horizontal seabed is D, and the interval between ultrasonic beam irradiation points (0 to 10 shown in the figure) on this seabed is d. Then, any ultrasound beam irradiation point n
The irradiation angle θn of the ultrasonic beam when irradiating the ultrasonic beam (n=1 to 10) is expressed as θn=tan ⁻¹ (nd/D).
Therefore, the ultrasonic beam irradiation point n is made to correspond to an address, and the value calculated using the angle calculation formula described above is written to each address as angle data. FIG. 4 shows a layout diagram of the data written in this manner. As is clear from FIG. 3, as the ultrasonic beam irradiation angle θ increases, the step angle of the ultrasonic beam becomes smaller.
That is, as the ultrasonic transducer 31 approaches the horizontal direction, its rotation speed becomes infinitely slow, so it is not practical to calculate the angle of the ultrasonic beam in the range of 0° to 90°. . Therefore, in this embodiment, the scanning control range of the ultrasonic beam so that the ultrasonic beam irradiation points are equally spaced is in the range of 0° to ±60°, and for the angle range exceeding this, the ultrasonic transducer 31 Angular data is written so that the motor is driven at a constant rotational speed.

The angle command data read from the table ROM 44 in which the ultrasonic beam irradiation angle data is written in this way is converted into an angle command voltage by the D/A converter 45, and then Amplifier 34 is provided.

By the way, the reflection detection signal detected by the ultrasonic transducer 31 is transmitted to the RAM 5 via the amplifier 51.
given to 2. The RAM 52 has a capacity to store a predetermined number of depth data obtained by emitting one ultrasonic beam, and addresses are set corresponding to the depth direction. The reflected wave detection signals are sequentially written to addresses specified by the write address setting circuit 53. The write address setting circuit 53 is
It is composed of a clock pulse generation circuit, a clock pulse counting circuit, a frequency dividing circuit, etc. (not shown), and starts counting clock pulses when it receives a transmission trigger output from the transmission trigger generation circuit 37. Therefore, the counted value corresponds to the depth, and this counted value (hereinafter referred to as the distance clock) is used as the write address data.
It is given to RAM52.

Note that, due to the storage capacity of the RAM 52, it is necessary to keep the number of samples of the reflected wave detection signal constant. Therefore, when the depth of the ocean floor increases, the number of samples of the reflection detection signal becomes constant by dividing the clock pulse.
52 overflow is prevented. For this purpose, the output of the range setter 41 is provided to a write address setting circuit 53 in order to vary the frequency division ratio according to the seabed depth.

On the other hand, the detection data written in the RAM 52 is repeatedly read out at high speed sequentially from the address specified by the read address setting circuit 54, so that the detection data written in the RAM 52 is read out repeatedly at high speed starting from the address specified by the read address setting circuit 54.
Indication) 55 is used to prevent flickering on the screen and to interpolate each sampled data in the detection direction. Note that the output of the potentiometer 33 is also given to the deflection circuit 56, and the output from the deflection circuit 56 is
It is configured such that a deflection voltage is applied to the PPI 55 according to the ultrasonic beam irradiation angle.

Next, the operation of the embodiment having the above-described configuration will be explained.

When a depth range is designated by the range setter 41, a reference pulse having a cycle corresponding to the depth range is outputted from the reference pulse generation circuit 42. counter 43
counts the reference pulses and stores them in the table ROM
44 addresses are specified. As a result, each time the reference pulse is output, the ultrasonic beam irradiation angle command data is read from the table ROM 44 and provided to the D/A converter 45. D/A converter 4
At 5, the angle command data is converted into an angle command voltage and applied to the differential amplifier 34. Then, the servo system consisting of the ultrasonic vibrator 31, differential amplifier 34, drive circuit 35, motor 32, and potentiometer 33 operates, and the ultrasonic vibrator 31 emits radiation corresponding to the command voltage. set at an angle. When the H→L detection circuit 36 detects that the ultrasonic transducer 31 is set at a predetermined irradiation angle, the transmission trigger generation circuit 37 outputs a transmission trigger to the ultrasonic transducer 31. Thereby, the ultrasonic beam is irradiated from the ultrasonic transducer 31 in the direction in which the angle is set.

The reflected waves of the ultrasonic beam thus irradiated are detected by the ultrasonic transducer 31. Then, the reflected wave detection signal of the ultrasonic transducer 31 is sampled in the depth direction and sequentially written into the RAM 52 addressed by the write address setting circuit 53. The detection data written in this way is stored in the read address setting circuit 5.
4 and are sequentially read out, one scanning line image in the detection direction is displayed on the PPI 55.

Then, whenever the reference pulse is output from the reference pulse generation circuit 42 within the range of the ultrasonic beam irradiation angle from 0° to ±60°, the same operation as described above is performed, and the ultrasonic beam The irradiation angle of the ultrasonic beam is controlled so that the irradiation points are equally spaced, and detection in each direction is performed. On the other hand, a range in which the ultrasonic beam irradiation angle exceeds the above angle range is detected by driving the ultrasonic transducer 31 at a constant speed. When the scanning of the angle range determined in this manner is completed, the count value of the counter 43 is cleared. Then, at the start of the next scan, the counter 43 newly counts the reference pulse, and the angle setting of the ultrasonic transducer 31 is sequentially performed.

Next, other embodiments of the present invention will be described. In the above embodiment, the emission period of the reference pulse is uniquely determined by the depth range set by the range setter 41 as depth data output means. That is, because it is necessary to irradiate the next ultrasonic beam after detecting the reflected waves that have returned from the seabed, the period of the reference pulse is set to the distance from the ultrasonic transducer 31 to the farthest point within the detection range. It has been decided accordingly. For example, as shown in FIG. 5, when detecting the ultrasonic beam irradiation angle within a range of 60 degrees, R=D/cos 60 degrees=2D. Therefore, when the reference pulse is irradiated at a period determined by the farthest point distance 2D, the distance shown by the broken line in Fig. 6, that is, the distance between the farthest point distance R (=2D) and each ultrasonic beam irradiation point. Only the time corresponding to the distance difference,
This results in detection with unnecessary waiting time.

In this embodiment, the ultrasonic beam irradiation points are equally spaced, the unnecessary waiting time as mentioned above is reduced, and the ultrasonic beam is irradiated with the minimum necessary waiting time to efficiently examine the submarine topography. It is what you are trying to detect. Therefore, in this embodiment, the seventh
The period of the reference pulse is determined by the depth data output means as shown in the figure. Note that the configuration other than the components shown in FIG. 7 is the same as the embodiment shown in FIG. 2, and therefore is omitted in FIG. 7.

In the same figure, the detection depth calculator 46 receives the ultrasonic beam irradiation angle command data from the table ROM 44 and the distance clock from the write address setting circuit 53, calculates r _o · sin θ, and calculates the detection point ( (sampling point). That is, as shown in FIG. 8, θ in the above equation is determined from the ultrasonic beam irradiation angle command data. Furthermore, since the distance clock gives the distances r ₁ to _{r o} to the detection points 1 to n shown in the figure, the depths d ₁ to d _o of each detection point can be determined from the above equation. When the depth of the detection point is calculated by the detection depth calculator 46, the calculation result is given as one input to the comparator 47. Comparator 47
compares the calculation result with the depth range set value D appropriately predicted and set by the range setter 41, and provides a match output to the reference pulse generation circuit 48 when the two match. Thereby, the reference pulse generation circuit 48 outputs the reference pulse to the counter 43. If the configuration is configured so that the reference pulse is output when the depth of the detection point matches the depth range setting value in this way, if the distance from the ultrasound transducer 31 to the ultrasound beam irradiation point is short, Correspondingly, the period of the reference pulse is also shortened, eliminating unnecessary waiting time. Therefore, in addition to the effects of the embodiments described above, this embodiment also has the unique effect of being able to efficiently perform seabed detection.

<Effects of the Invention> As is clear from the above description, according to the scanning control device for a submarine topography detection sonar according to the present invention, ultrasonic waves are emitted so that the ultrasonic beam irradiation points are equally spaced on the horizontal seabed. Since beam scanning can be performed, it is possible to accurately grasp not only the area directly below the ultrasonic transducer, but also the long-distance seabed topography directly below the ultrasonic transducer.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing the configuration of the present invention, and FIG. 2 is a block diagram schematically showing the configuration of a submarine topography detection sonar using an embodiment of the present invention.
FIG. 3 is an explanatory diagram of ultrasonic beam irradiation angle calculation in the embodiment, FIG. 4 is a data arrangement diagram of the table ROM 44, and FIGS. 5 and 6 are diagrams for explaining the unique purpose of the second embodiment. , FIG. 7 is a block diagram schematically showing the constituent parts of the second embodiment, FIG. 8 is an explanatory diagram of the operation of the second embodiment, and FIG. 9 is an explanatory diagram of ultrasonic beam scanning by a conventional apparatus. 10...Scanning control device, 11...Depth data output means, 12...Reference pulse generation circuit, 13...
Reference pulse counting means, 14... Ultrasonic beam irradiation angle storage means, 20... Ultrasonic beam irradiation means.

Claims (1)

[Scope of Claims] 1. A scanning control device for a submarine topography detection sonar that scans an ultrasonic beam in a fan shape toward the ocean floor based on sequentially giving ultrasonic beam irradiation angle command data to an ultrasonic beam irradiation means. Depth data output means for providing depth data related to the depth of the seabed; Reference pulse generation means for generating reference pulses at a period determined based on the depth data provided from the depth data output means; A reference pulse counting means for counting the reference pulses given from the reference pulse generating means, and an ultrasonic beam irradiation angle in which ultrasonic beam irradiation angle data is written so that the ultrasonic beam irradiation points are equidistant with respect to the horizontal seabed. and storage means, the ultrasonic beam irradiation angle storage means receives the counting output of the reference pulse counting means and stores the ultrasonic beam irradiation angle data written in the address corresponding to the counting output. What is claimed is: 1. A scanning control device for a submarine topography detection sonar, characterized in that the scanning control device applies the following to an ultrasonic beam irradiation means.