JP3004433B2 - Underwater acoustic signal transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting underwater acoustic signals.

[0002]

2. Description of the Related Art In a method of transmitting an underwater acoustic control signal from a mother ship to a cableless submersible or the like, conventionally, a transmission error is detected by a parity check, a checksum, or the like.
The previous control signal is continued.

Here, the parity check adds one bit to the n-bit information, adjusts the sum so that the sum is always odd (or even), and the receiving side is even (or odd).
In this case, the parity check is normally performed on the eighth bit in the case of 1 byte in the method of detecting an error.
Assuming that four types of 1-byte information are sent, for example, the checksum is sent one byte at a time in order, and after the fourth, a sum signal of four more, that is, a total of five signals is sent. When the sum signal is not equal to the sum of the four signals, the receiving side detects the error as an error.

[0004]

However, in such a conventional signal transmission method, even if an error is found, the previous control signal is continued without correction. However, even if there is only one error, if the frame is continuous, it may not be useful as a control signal, and the submersible may not be able to control.
In particular, the cableless underwater acoustic communication is easily affected by the reflected sound from the water surface and the sea floor, and the error rate cannot be reduced to zero.

[0005] The present invention has been proposed in view of such circumstances, and even if the received data contains a certain error,
It is an object of the present invention to provide a method of transmitting an underwater acoustic signal in which a correct control signal is estimated from obtained data and a submersible or the like is remotely operated so as not to fall into an uncontrolled state.

[0006]

For this purpose, the present invention relates to an underwater acoustic communication of a control signal sent from a mother ship to an unmanned submersible. In the underwater acoustic communication, the control signal is converted into a plurality or a single straight line indicating the control direction and the magnitude on the mother ship. Create on the screen, transmit this pixel signal from the transmitter, perform Hough transform of the pixel signal obtained by the receiver via the underwater medium and perform multiple or singular linear approximation,
The transmission error is corrected by obtaining a control signal to the unmanned underwater vehicle based on the vertical and horizontal positions with respect to the origin of the approximate straight line.

[0007]

According to this structure, the transmitting side converts the control signal into a group of straight lines with the origin (center of the image) as a reference point, and determines the direction and direction of the control signal based on the position and distance of the straight line with respect to the origin. Convert to represent degree. A binary signal (pixel signal) of the straight line is transmitted, and a group of straight lines is approximately reproduced on the receiving side based on the binary signal including a transmission error. By using the Hough transform for this linear approximation, multiple linear approximations are possible. The receiving side estimates the direction and degree of control based on the positional relationship and distance between the obtained approximate straight line and the origin,
Control can be performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall conceptual diagram, FIG. 2 is a block diagram showing a transmission / reception system on the mother ship side and the unmanned submersible side in FIG. 1, and FIG. 4, FIG. 4 is an explanatory diagram showing an example of the pixel decomposition of FIG. 3, FIG. 5A is an approximate linear diagram of the reception side in FIG. 2, and FIG. 5B shows an example of the pixel decomposition. FIG. 6 is an equation showing the relationship between ρ and θ of each pixel in FIG. 5B, FIG. 7 is a bilinearized diagram in FIG. 5A, and FIG.
It is an overall flowchart in the case of original control.

First, in FIG. 1, it is assumed that a control signal is given from the transmitter 3 from the mother ship 2 to the unmanned submersible 1 by the operator to move forward at a low speed. This transmission signal is linearized along the arrow in the block diagram of FIG.
The wave is transmitted from the transmitter 3 into the water through the K modulator and the amplifier.
At this time, the transmitting side first converts this into two orthogonal straight lines as shown in FIG. Here, the horizontal axis represents forward / backward movement, and the vertical axis represents left / right movement. Now, since the transmission signal is a forward movement at a low speed, the horizontal axis is slightly above the origin, and the vertical axis is on the origin. This straight line is divided into, for example, 64 × 64 pixels, and a binary signal corresponding to the pixel is PSK (Pha
5 by the “Shift Keying” method.
As shown in (A), a change in the phase of the longitudinal transmission is transmitted in accordance with a data sequence of "0" or "1". PSK
The system is capable of constrained data transmission. Then, on the receiving side, as shown in the block diagram in the lower half of FIG.
The SK signal is received, and the received signal first passes through a demodulator (correction of a signal due to phase distortion), and then performs a Hough transform based on the pixel signal to perform a linear approximation to obtain a reception signal as shown in FIG. Get an image.

For the sake of convenience, it is assumed that FIG. 3 is transmitted by dividing it into, for example, 13 pixels shown in FIG. By the way, on the receiving side due to disturbance, (−3, 2),
(−1,2), (1,2), (3,2), (0,1),
Assuming that only seven pixels (0, -1) and (0, -3) can be received, FIG. 5B is obtained as a received image. Each pixel is represented by the following formulas (1) to (3) by Hough transform, and when this is represented by θ as a variable, the diagram shown in FIG. 6 is obtained. ρ = −3 cos θ + 2 sin θ ρ = −1 cos θ + 2 sin θ ρ = cos θ + 2 sin θ ρ = 3 cos θ + 2 sin θ ρ = sin θ ρ = −sin θ ρ = −3 sin θ In FIG. Looking at the range of 0 ≦ θ <π, the point P ₁ (2,
There are four lines passing through (π / 2) and three lines passing through the point P ₂ (0,0). These two points P ₁ and P ₂ are the top two points of the line overlap, and the rest are two. There are 12 intersecting points. As a result, as shown in the equations, two straight lines converted into the x and y planes are obtained again. 2 = xcosπ / 2 + ysinπ / 2 and 0−xcos0 + ysin0... When these are arranged, two lines of y = 2 ← forward / backward traveling signals x = 0 ← left / right turning signals... This does not deviate from the diagram shown in FIG. 3 earlier, and thus, despite the disturbance, FIG. 3 is reproduced in the same form after being received.

[0011] Generally speaking, what has been described above is ρ-
Point P ₁ (ρ ₁ , θ ₁ ) where the curve in θ space intersects most
By finding a point P ₂ (ρ ₂ , θ ₂ ) that intersects with the following _two points, _two straight lines ρ ₁ = xcos θ ₁ + ysin θ ₁ ρ ₂ = xcos θ ₂ −ysin θ ₂ are obtained (FIG. 7). Since the slope of the straight line is determined on the transmitting side (in this case, parallel to the horizontal axis and the vertical axis), a case where the obtained approximate straight line cos θ ₁ or cos θ ₂ is close to zero is regarded as a forward / backward control signal, and cos (θ ₁ − △ θ ₁ ) by correcting the approximation line so that ρ ₁ / sin (θ− △ θ ₁ )
Similarly, ρ ₂ / cos (θ ₂ − △ θ ₂ ) can be used as the control amount.

In the above, the case of the dual control of the forward and the left and right control has been described.
As shown in FIG. Note that, in FIG. 1 described above, since no correction was necessary, this was omitted, but if the following two equations were obtained by Hough transform, 2 = xcos (1.70) + ysin (1. 70) (α) 0 = xcos (0.15) + ysin (0.15) (β) Since the transmitting side is transmitting a signal in which the x coefficient of the expression α is 0, cos (1 .70− △ θ ₁ ) = 0
₁ is obtained, from which Δθ ₁ ≒ 0.13 is obtained. Similarly, since the y coefficient of equation β is 0 and sin (0.15) = 0, the control signal is y = 2 / sin (1.70−0.13) ≒ 2 x = 0 since △ θ ₂ ≒ 0.15. /Cos(0.15-0.15)≒0.

When performing one-way control instead of two-way control,
For example, only the forward / reverse control signal is transmitted. In this case, Y = 2
Since only the signal of
From this, y = 2, and a forward / backward traveling signal at a medium speed is obtained.

[0014]

In general, in underwater acoustic communication, making the transmission error rate as close as possible to zero not only takes much transmission time, but also cannot make it completely zero. In the meantime, according to the present invention, the true value is estimated from the information including the transmission error by using the method of linear approximation and controlled, whereby the uncontrolled state of the cableless submersible can be prevented. The method of the present invention is also applicable to transmission of an output signal of an underwater camera mounted on a submerged ship to a mother ship.

In short, according to the present invention, in underwater acoustic communication of a control signal sent from a mother ship to an unmanned submersible vehicle, a control signal is created on the screen in a plurality or a single straight line indicating the control direction and the magnitude on the mother ship. This pixel signal is transmitted from the transmitter, and the pixel signal obtained by the receiver via the underwater medium is subjected to Hough transform to perform plural or singular linear approximation. By correcting the transmission error by obtaining the control signal to the unmanned submersible by the above, even if the received data contains errors to some extent, it estimates the correct control signal from the obtained data and controls the submersible etc. The present invention is extremely useful in industry because it provides a method for transmitting underwater acoustic signals that is remotely controlled so as not to fall into a state.

[Brief description of the drawings]

FIG. 1 is an overall conceptual diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram illustrating a transmission / reception system on the mother ship side and the unmanned submersible side in FIG.

FIG. 3 is a transmission signal diagram in FIG. 2;

FIG. 4 is an explanatory diagram showing an example of the pixel decomposition of FIG. 3;

5A is an approximate linear diagram on the receiving side in FIG. 2, and FIG. 5B is an explanatory diagram showing an example of pixel decomposition.

FIG. 6 is an equation showing a relationship between ρ and θ of each pixel in FIG. 5 (B).

FIG. 7 is a two-linearized diagram of FIG.

FIG. 8 is a flowchart in the case of binary control.

[Explanation of symbols]

 1 Unmanned submersible 2 Mother ship 3 Transmitter 4 Receiver

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B63C 11/00 G05D 1/00

Claims (1)

(57) [Claims] In underwater acoustic communication of a control signal transmitted from a mother ship to an unmanned submersible, a control signal is created on a screen in a plurality or a single straight line indicating a control direction and a magnitude on the mother ship,
Transmit this pixel signal from the transmitter, perform Hough transform on the pixel signal obtained by the receiver via the underwater medium, and perform multiple or single linear approximation. An underwater acoustic signal transmission method, wherein a transmission error is corrected by obtaining a control signal to the unmanned submersible.