JPH11202042A - Underwater positioning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring the position of a transmitter by two receivers and depth data and to simplify a device by transmitting the depth data as pulse intervals. SOLUTION: A signal being transmitted from a transmitter 5 of an underwater object 2 is received by first and second receivers, an angle θx formed by a straight line L and a straight line (m) is obtained by a distance L between the transmitter 5 and the second receiver, a distance (m) between the first receiver and the second receiver, and a phase difference Δt of that signal from the transmitter 5 which the first and second receivers have received, a depth meter 4 is mounted on the underwater object 2 and a depth D is transmitted by the above signal, and the depth D received at least by one receiver 3 is found a surface that includes the straight line (m) and orthogonally crosses a depth direction is set to an XY plane, and the X and Y coordinates of the transmitter 5 are calculated by using the distance L, the angle θx, and the depth D are calculated in the X and Y coordinates with the position of the second receiver as a zero point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an underwater positioning system for measuring the position of an underwater object from a signal transmitted from the underwater object.

[0002]

2. Description of the Related Art An ultrasonic signal transmitted from a transmitter of an underwater object is received by three receivers arranged on the same plane, and the phase difference between a and b, c and b shown in FIG. The depth of the underwater object and the position on the horizontal plane, that is, the three-dimensional position are calculated. However, in this method, the calculation is complicated, so that the operation circuit is complicated and the calculation time is long. Further, when the underwater object is at a shallow depth, the depth error increases.

Japanese Patent Application Laid-Open No. 57-46171 discloses a method in which a depth gauge is mounted on an underwater object, the measured depth is frequency-modulated, transmitted as an ultrasonic wave, and a position on a horizontal plane is obtained based on data received by three receivers. Is calculated, and data received by one receiver is demodulated to obtain depth data. Thereby, the three-dimensional position of the underwater object is calculated. Since the data of the depth can be used as it is and the calculation on the horizontal plane is simplified, the calculation is short and the error of the depth is eliminated.

[0004]

The apparatus disclosed in the above publication requires three receivers, which complicates the apparatus. In addition, a method is employed in which depth data is frequency-modulated, propagated in water as ultrasonic waves, frequency-demodulated on the receiving side, and depth is extracted, and the apparatus is complicated.

The present invention has been made in view of the above problems, and has as its object to provide a method of measuring the position of a transmitter using two receivers and data of depth. Another object of the present invention is to simplify the apparatus by transmitting depth data as pulse intervals.

[0006]

According to a first aspect of the present invention, a signal transmitted from a transmitter of an underwater object is received by a first receiver and a second receiver. A straight line is obtained by using the distance L to the second receiver, the distance m between the first receiver and the second receiver, and the phase difference Δt of the signals received by the first and second receivers from the transmitter. The angle θx between L and the straight line m is obtained, a depth gauge is mounted on the underwater object, the depth D is transmitted by the signal, and the depth D received by at least one of the receivers is obtained. X, with the plane orthogonal to the depth direction as the XY plane and the position of the second receiver as the origin
In the Y coordinate, the X and Y coordinates of the transmitter are calculated using the distance L, the angle θx, and the depth D.

As shown in FIG. 6, when the first receiver a and the second receiver b are apart from each other by a distance m and the sound source (transmitter) is an extension of the straight line m, the reception signals of both receivers are as shown in FIG. Δt as shown
Δt · v obtained by multiplying this deviation by the sound velocity v is m (m = Δ
tv). When the sound source intersects the straight line m at an angle θx as shown in FIG. 6, the distance between a and b with respect to the sound source is n, and n = Δt · v. Thus, COS θx = n
/ M can be determined. In FIG. 5, when the intersection of the vertical line from the sound source O and the XY plane is P, a straight line OP represents a vertical distance d between the sound source O and the receiving unit 3 derived from the depth D, and a straight line Ob represents the sound source O and the second reception line. Represents the distance L from the container b. The XY coordinates of the point P are represented by the following equation. X = L · COS θx (1) Y = √ (h ² −X ² ) = √ ((L ² −d ² ) −X ² )) (2)

According to a second aspect of the present invention, in the first aspect of the present invention, a third receiver is provided on a line orthogonal to the straight line m on the XY plane and passing through a position of the second receiver, and together with the second receiver. The X and Y coordinates of the transmitter are calculated.

[0009] XY only in the first receiver a and the second receiver b
Since all the quadrants of the coordinates cannot be specified, the third receiver c is provided on a straight line that passes through b and is orthogonal to the straight line m in FIG.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the signal for transmitting the depth D includes two pulses, and the pulse interval represents the depth D.

A signal corresponding to the measured value of the depth gauge corresponding to the interval between two pulses is generated, and this signal is transmitted by the transmitter.
Each receiver receives this signal, but obtains a depth D from the received data of one of the receivers.

According to a fourth aspect of the present invention, in the first or second aspect of the invention, the signal for receiving the distance L is provided with a timer which operates at the same timing in any one of the receiver and the transmitter, and the transmitter transmits the signal at a predetermined time. The receiver calculates the signal propagation time from the difference between the predetermined time and the time at which the signal was received, and calculates the distance L from the propagation time.

When the signal propagation time is obtained by the above method, the distance L can be obtained by multiplying the propagation time by the speed of sound in water.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of the present embodiment. A receiving unit 3 is provided so as to protrude from the bottom of the marine vessel 1, and a depth gauge 4 and a depth D measured by the depth gauge 4 are converted into a pulse and transmitted by ultrasonic waves to an underwater object 2 moving underwater. A transmission unit 5 is provided. The depth D indicates the vertical distance between the water surface and the depth gauge 4,
The vertical distance d between the receiving unit 3 and the transmitting unit 5 is represented by the following equation. d = D−Δd1−Δd2 (3) Δd1: vertical distance between the water surface and the receiving unit 3 Δd2: vertical distance between the transmitting unit 5 and the depth gauge 4

FIG. 2 is a block diagram showing the configuration of the transmitting section 5. The depth display pulse generator 20 converts a voltage or current value representing the depth D obtained from the depth meter 4 into a depth pulse 22 representing the depth D in accordance with the timing from the first timer 21. The depth pulse 22 is composed of two pulses as shown in the figure, and is converted so that the interval k between them has a fixed relationship with the depth D. The depth pulse 22 is generated at a constant cycle T. FIG. 3 shows the interval k of the depth pulse 22 and the depth D.
In this example, the interval k and the depth D are in a proportional relationship.

The preamplifier 23 amplifies the voltage of the depth pulse 22, and the power amplifier 24 further amplifies the power. The transmitter 25 is composed of an oscillator such as a crystal oscillator, converts the power-amplified depth pulse 22 into an ultrasonic wave, and transmits the ultrasonic wave into water.

FIG. 4 is a block diagram showing the configuration of the receiving section 3. As shown in FIG. Reference numeral 30 denotes three first receivers a, second receivers b,
FIG. 6 is a diagram showing the arrangement of the receiver c, on the horizontal plane (XY plane), the second receiver b at the origin, the first receiver a at a distance of m from the origin on the X axis, and the first receiver a at a distance m1 from the origin on the Y axis. 3 receivers c are arranged.

Each of the receivers ac receives the ultrasonic wave from the transmitter 25, converts the ultrasonic wave into an electric signal, and demodulates the depth pulse 22 shown in FIG. The COS θx calculator 31 calculates COS θx from the outputs of the first receiver a and the second receiver b or the outputs of the second receiver b and the third receiver c. θx is sound source O
A straight line L representing the distance L between the (transmitter 5) and the second receiver b
And an intersection angle of a straight line m representing a distance m between the first receiver a and the second receiver b, or a straight line L, and a straight line m1 representing a distance m1 between the second receiver b and the third receiver c. Is the intersection angle with

The depth calculator 32 is connected to one of the receivers (FIG. 4)
Then, the depth D is calculated from the pulse interval k of the received signal of the first receiver a). The second timer 33 is the first timer 2 of the transmitting unit.
It has the same timing function as 1 and is synchronized before the start of measurement. The distance calculator 34 calculates the second receiver b from the transmission time preset in the first timer 21 and the second timer 33.
Calculates the sound wave propagation time up to the time of reception, and multiplies this time by the speed of sound in water to calculate the distance L between the sound source O and the second receiver b. The three-dimensional coordinate calculation unit 35 substitutes the vertical distance d between the receiving unit 3 and the transmitting unit 5 derived from COS θx, distance L, and depth D into the above equations (1) and (2), and
Calculate the Y coordinate. The X and Y coordinates are coordinates provided on a horizontal plane with the second receiver b as the origin. By adding the depth D as the Z coordinate to the X and Y coordinates, the sound source O (transmitting unit 5)
Are obtained. The position display unit 36 displays the sound source O calculated by the three-dimensional coordinate calculation unit 35, that is, the three-dimensional position of the underwater object 2 on the screen.

FIG. 5 is an explanatory diagram showing the position of the sound source O in three-dimensional coordinates. FIG. 6 shows an intersection angle θ between a straight line m representing a straight line distance m between the first receiver a and the second receiver b and a straight line from the sound source O.
FIG. 9 is an explanatory diagram for obtaining x. FIG. 7 shows the phase difference between the received signals from the sound source O received by the first receiver a and the second receiver b. Hereinafter, a method of displaying the position of the sound source O in three dimensions will be described with reference to FIGS.

In FIG. 5, receivers a, b, and c are arranged on a horizontal plane (these planes are defined as X and Y planes), and a is arranged at a distance m on the X axis with b as the origin and on the Y axis. To distance m1
C is located away. The coordinates orthogonal to the X and Y planes and passing through the origin are defined as Z coordinates. Vertical line passing through sound source O and X, Y
Assuming that the intersection point with the plane is P, the distance OP represents d shown in Expression (3). The intersection of the perpendicular drawn from the point P to the X axis and the X axis represents the X coordinate of the sound source O, and the intersection of the perpendicular drawn to the Y axis and the Y axis represents the Y coordinate of the sound source O. The distance between the diagonal lines bP is h. The distance between the sound sources O and b is L. The intersection angle between the straight line L and the straight line m is defined as θx. Note that, depending on the position of the sound source O, the intersection angle between the straight line L and the straight line m1 is θx. As described above, the distance L is determined by the first timer 21 and the second timer 33.
Is calculated from the transmission time set in advance to the time when the second receiver b receives the sound wave, and this time is multiplied by the sound speed in water. d is obtained by equation (3),
m and m1 are constants.

A method for obtaining θx will be described with reference to FIGS. Sound waves are transmitted from the sound source O to the first receiver a and the second receiver b almost in parallel. A straight line is drawn from the point b to the sound source O, and a point at which the vertical line from the point a intersects this straight line is e,
Assuming that the distance of the straight line be is n, the angle abe is the intersection angle θx
Becomes Therefore, COS θx = n / m. Here, n is the difference in the distance between a and b from the sound source O, and this difference is calculated from the phase shift of the signals received by the first receiver a and the second receiver b. As shown in FIG. 7, a phase shift of Δt occurs between the waveforms of the received signals of the first receiver a and the second receiver b.
The value obtained by multiplying the phase shift Δt by the sound velocity v in water is n (n = Δt · v). As a result, COS θx and θx can be obtained, and X, Y of the sound source O can be obtained using the equations (1) and (2).
The coordinates can be calculated. Further, by taking d as the Z coordinate, the three-dimensional coordinates of the sound source O can be obtained.
In the above description, the case where the sound source O is on the X axis side has been described.
If it is on the Y-axis side, COS θx is calculated using the distance m1 between the second receiver b and the third receiver c. Sound source O is X axis and Y
When it is at the middle of the axis, either m or m1 may be used.

[0023]

As is clear from the above description, according to the present invention, an ultrasonic wave indicating the depth of an underwater object is transmitted and transmitted.
The three-dimensional position of the underwater object can be calculated by obtaining the position on the horizontal plane received by the receiver and adding depth data to the position. In addition, by displaying the depth at intervals of two pulses, it is possible to easily generate a depth signal, convert to an ultrasonic wave, and convert the ultrasonic wave to a pulse signal.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a transmission unit.

FIG. 3 is a diagram showing a relationship between a pulse interval k and a depth D.

FIG. 4 is a block diagram illustrating a configuration of a receiving unit.

FIG. 5 is an explanatory diagram for calculating a position of a sound source O;

FIG. 6 is an explanatory diagram for obtaining an intersection angle θx between a straight line m connecting a first receiver a and a second receiver b and a path of a sound wave from a sound source O;

FIG. 7 is a diagram for explaining a phase shift between received signals of a first receiver a and a second receiver b.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ship 2 Underwater object 3 Receiving part 4 Depth gauge 5 Transmitting part 20 Depth display pulse generator 21 First timer 22 Depth pulse 23 Preamplifier 24 Power amplifier 25 Transmitter 30 Receiver arrangement 31 COSθx calculating part 32 Depth calculating part 33 2 timer 34 distance calculation unit 35 three-dimensional coordinate calculation unit 36 position display unit a first receiver b second receiver c third receiver O sound source

Claims (4)

[Claims] 1. A signal transmitted from a transmitter of an underwater object is received by a first receiver and a second receiver, a distance L between the transmitter and the second receiver, a first receiver, and a second receiver. Distance m and the first
The angle θx between the straight line L and the straight line m is obtained by using the phase difference Δt of the signal from the transmitter received by the receiver and the second receiver, and a depth gauge is mounted on the underwater object, and the depth D is obtained. An X, Y coordinate transmitted by the above-mentioned signal and obtained by at least one of the receivers to obtain a depth D, a plane including the straight line m and orthogonal to the depth direction is defined as an XY plane, and the position of the second receiver is set as an origin. , The X of the transmitter using the distance L, the angle θx, and the depth D,
An underwater positioning method characterized by calculating a Y coordinate. A second line orthogonal to the straight line m on the XY plane;
Providing a third receiver on a line passing through the position of the receiver;
The underwater positioning system according to claim 1, wherein the X and Y coordinates of the transmitter and the receiver are calculated. 3. The underwater positioning system according to claim 1, wherein the signal for transmitting the depth D includes two pulses, and the pulse interval indicates the depth. 4. A signal which receives the distance L is provided with a timer which operates at the same timing in one of the receiver and the transmitter, the transmitter transmits the signal at a predetermined time, and the receiver receives the signal at the predetermined time. 3. The underwater positioning system according to claim 1, wherein a signal propagation time is obtained from a difference between the times, and the distance L is calculated from the propagation time.