Ship speed measuring device

Abstract

To provide a ship speed measuring device that can mitigate the risk of reduced measurement accuracy due to loss of ultrasonic waves. [Solution] Two of the three transceivers 21, 22, and 23 are arranged so that ultrasonic waves are transmitted symmetrically with respect to the axis (Y-axis) connecting the bow and stern. If the Doppler frequencies fd1, fd2, and fd3 of the reflected waves received by any one of the three transceivers 21, 22, and 23 cannot be obtained, the computing computer 4 calculates the ground speeds Ug in the port and starboard directions and Vg in the bow and stern directions, assuming that the elements of these Doppler frequencies fd1, fd2, and fd3 and the vertical ground speed Wg are absent.

Description

Technical Field

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[0001] The present invention relates to a ship speed measuring device that transmits ultrasonic waves from a ship into water and measures the ship speed of the own ship by utilizing the Doppler effect of the reflected wave (echo).

Background Art

[0002] In a conventional ship speed measuring device that utilizes the Doppler effect, mainly the pair beam method (Janus method) is used (see, for example, Patent Document 1). That is, in order to reduce the error given to the measured value by the heaving (vertical movement), pitching, and rolling of the hull, ultrasonic beams having a certain depression angle are radiated in a plurality of azimuth directions, and the ship speed is calculated from the Doppler shift amount of the reflected wave. For example, in a ship speed measuring device that measures the speed in the bow direction and the speed relative to water and relative to land in the side direction, two pairs of beams for one axis are provided to form ultrasonic beams in four different azimuth directions, or ultrasonic beams in three different azimuth directions are formed as a minimum configuration to calculate the ship speed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, due to accidental failures or the like, the ultrasonic beam in one direction may be lost and the Doppler shift amount may not be obtained. In such a case, the error given to the measured value by heaving, pitching, and rolling becomes large, and the measurement accuracy decreases. And such a decrease in measurement accuracy becomes a major obstacle in the operation of the ship. For example, if the speed relative to land in the side direction cannot be accurately measured, there is a risk that approaching or leaving the shore cannot be performed properly and safely.

[0005] Therefore, the present invention aims to provide a ship speed measuring device that can reduce the risk of decreased measurement accuracy due to the loss of ultrasonic waves. [Means for solving the problem]

[0006] To solve the above problems, the invention described in claim 1 is a ship speed measuring device comprising three transceivers, each arranged to transmit ultrasonic waves into the water from a ship and receive reflected waves from the seabed, so as to transmit ultrasonic waves in different declination directions, and a calculation means for calculating the ground speed in the bow-stern direction, port-starboard direction and vertical direction based on the Doppler frequencies of the reflected waves received by the three transceivers, wherein two of the three transceivers are arranged so as to transmit ultrasonic waves symmetrically with respect to an axis connecting the bow and stern, and if the Doppler frequency of the reflected wave received by any one of the three transceivers cannot be obtained, the calculation means calculates the ground speed in the bow-stern direction and port-starboard direction, assuming that the elements of the Doppler frequency and vertical ground speed do not exist.

[0007] The invention described in claim 2 is a ship speed measuring device comprising three transceivers, each arranged to transmit ultrasonic waves into the water from a ship and receive reflected waves from the water, so as to transmit ultrasonic waves in different declination directions, and a calculation means for calculating the water speed in the bow-stern direction, port-starboard direction and vertical direction based on the Doppler frequencies of the reflected waves received by the three transceivers, wherein two of the three transceivers are arranged so as to transmit ultrasonic waves symmetrically with respect to an axis connecting the port and starboard sides, and if the Doppler frequency of the reflected wave received by any one of the three transceivers cannot be obtained, the calculation means calculates the water speed in the bow-stern direction and port-starboard direction, assuming that the elements of the Doppler frequency and vertical water speed do not exist. [Effects of the Invention]

[0008] According to the invention described in claim 1, since two transceivers are arranged so that ultrasonic waves are transmitted symmetrically with respect to the axis connecting the bow and stern, the angular deflection direction of one transceiver can be expressed by the angular deflection direction of the other transceiver (reducing the number of parameters). Furthermore, if the Doppler frequency of one reflected wave cannot be obtained, the angular deflection direction of the bow-stern and port-starboard directions is calculated by omitting this Doppler frequency and the element of vertical ground speed, which generally has a small speed (and therefore a small impact on the measurement). In this way, the angular deflection direction of the bow-stern and port-starboard directions can be obtained using only the two obtained Doppler frequencies, thereby reducing the risk of reduced measurement accuracy due to the loss of ultrasonic waves and reflected waves.

[0009] According to the invention described in claim 2, since two transceivers are arranged so that ultrasonic waves are transmitted symmetrically with respect to the axis connecting the port and starboard sides, the angular deflection direction of one transceiver can be represented by the angular deflection direction of the other transceiver (reducing the number of parameters). Furthermore, if the Doppler frequency of one reflected wave cannot be obtained, the angular deflection direction of the water in the bow-stern direction and the port-starboard direction is calculated by assuming that this Doppler frequency and the vertical water velocity element, which generally has a small speed (and therefore a small impact on the measurement), are absent. In this way, the angular deflection direction of the water in the bow-stern direction and the port-starboard direction can be obtained using only the two obtained Doppler frequencies, thereby reducing the risk of reduced measurement accuracy due to the loss of ultrasonic waves and reflected waves. [Brief explanation of the drawing]

[0010] [Figure 1] These are a plan view (a) and a front view (b) showing a schematic configuration for measuring ground speed in a ship speed measuring device according to an embodiment of the present invention. [Figure 2] Figure 1 shows a plan view (a) and a side view (b) illustrating the schematic configuration for measuring the speed relative to the water in the ship speed measuring device. [Modes for carrying out the invention]

[0011] The present invention will be described below based on the illustrated embodiments.

[0012] Figures 1 and 2 show a schematic configuration for measuring ground speed and water speed in a ship speed measuring device 1 according to an embodiment of the present invention. This ship speed measuring device 1 transmits ultrasonic waves from a ship S to the water W1 and measures the ground speed and water speed of the ship S by utilizing the Doppler effect of the reflected waves (echoes).

[0013] Herein, this ship speed measuring device 1 differs from conventional ship speed measuring devices in that it can accurately measure speed even if ultrasonic Doppler frequencies are lost. A detailed explanation of the configuration equivalent to that of conventional ship speed measuring devices will be omitted, but the speed is calculated and measured in general as follows.

[0014] Specifically, for measuring ground speed, the vessel S is equipped with three ground transceivers 21, 22, and 23, which transmit ultrasonic waves to the underwater W1 at a predetermined deflection angle θg with respect to the Z axis in directions with different deflection angles Φ1g, Φ2g, and Φ3g, respectively, and receive reflected waves (ground echoes) from the seabed W2. Then, based on the Doppler frequencies (Doppler shift amounts) fd1, fd2, and fd3 of the reflected waves received by the three ground transceivers 21, 22, and 23, the computing computer (calculation means) 4 calculates the ground speed Vg in the bow-stern direction, the ground speed Ug in the port-starboard direction, and the ground speed Wg in the vertical direction.

[0015] Similarly, for measuring water velocity, the vessel S is equipped with three water-seeking transceivers 31, 32, and 33, which transmit ultrasonic waves to the underwater W1 at a predetermined deflection angle θw with respect to the Z axis in directions with different deflection angles Φ1w, Φ2w, and Φ3w, respectively, and receive reflected waves (water-seeking echoes from underwater targets such as plankton) from the underwater W1 at a predetermined depth. Then, based on the Doppler frequencies (Doppler shift amounts) fd1, fd2, and fd3 of the reflected waves received by the three water-seeking transceivers 31, 32, and 33, the computing computer 4 calculates the water-seeking velocity Vw in the bow-stern direction, the water-seeking velocity Uw in the port-starboard direction, and the water-seeking velocity Ww in the vertical direction relative to the current at that depth.

[0016] Here, the ground speed Vg and water speed Vw in the bow-stern direction (Y-axis direction) are defined as the Y-axis velocity V, the ground speed Ug and water speed Uw in the port-starboard direction (X-axis direction) are defined as the X-axis velocity U, and Let Wg be the ground velocity and Ww be the water velocity in the downward direction (Z-axis direction), and let θg and θw be predetermined angles of deviation with respect to the Z-axis, respectively. Let Φ1 be the deviation angle Φ1g and Φ1w, Φ2 be the deviation angle Φ2g and Φ2w, and Φ3 be the deviation angle Φ3g and Φ3w. Then the Y-axis velocity V, X-axis velocity U, and Z-axis velocity W can be calculated from the following equation 1. This means that by measuring the Doppler frequencies fd1, fd2, and fd3 in three directions, the velocities V, U, and W in each direction can be calculated and obtained.

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[0017] In addition to this basic configuration, as shown in Figure 1, in this ship speed measuring device 1, two of the three ground-to-ground transceivers 21, 22, and 23, 22 and 23, are arranged so that ultrasonic waves are transmitted symmetrically with respect to the axis connecting the bow and stern (Y-axis). That is, the first ground-to-ground transceiver 21 is arranged to transmit ultrasonic waves in the Y-axis direction, and the second and third ground-to-ground transceivers 22 and 23 are arranged so that their respective ultrasonic waves are transmitted symmetrically with respect to the Y-axis. Therefore, Declination angle Φ3g=π-Declination angle Φ2g It can be expressed as follows.

[0018] When the Doppler frequencies fd1, fd2, and fd3 of the reflected waves received by any one of the three ground transmitters / receivers 21, 22, and 23 cannot be obtained, the arithmetic computer 4 calculates the ground speed Ug (X-axis direction speed U) in the left and right directions and the ground speed Vg (Y-axis direction speed V) in the bow and stern directions, assuming that the non-obtainable Doppler frequencies fd1, fd2, and fd3 and the element of the ground speed Wg (Z-axis direction speed W) in the vertical direction are absent (excluded).

[0019] That is, when substituting the declination Φ3g = π - declination Φ2g into the above formula 1, formula 1 is expressed as the following formula 2.

Equation

[0020] When the first Doppler frequency fd1 cannot be obtained (in the case of a failure of the first ground transmitter / receiver 21, etc.), the element related to the non-obtained first Doppler frequency fd1 and the Z-axis direction speed W is removed, and the 3x3 matrix of formula 2 is reduced to the 2x2 matrix shown in the following formula 3. Then, by inverting this matrix, the ground speed Ug (U) in the left and right directions is calculated by the following formula 4, and the ground speed Vg (V) in the bow and stern directions is calculated by the following formula 5.

Equation

Equation

Equation

[0021] Thus, even if the first Doppler frequency fd1 cannot be obtained, the port and starboard ground speeds Ug(U), which are important for measuring ground speed during docking and undocking, can be acquired without being affected by the bow-stern ground speed Vg(V) or the vertical ground speed Wg(W). Furthermore, if the vertical ground speed Wg(W) is zero, the bow-stern ground speed Vg(V) can be acquired without error using equation 5. On the other hand, if the vertical ground speed Wg(W) is not zero, an error occurs, but generally, the heaving speed-ground speed Wg(W) for a ship S is small, so the influence of the ground speed Wg(W) is small and the error is also small.

[0022] Similarly, if the second Doppler frequency fd2 cannot be obtained (for example, due to a failure of the second ground transceiver 22), the elements relating to the unobtained second Doppler frequency fd2 and the Z-axis velocity W are removed, and the matrix in Equation 2 is reduced to the 2x2 matrix shown in Equation 6 below, in order to calculate the ground velocity Ug(U) in the port and starboard directions and the ground velocity Vg(V) in the bow and stern directions.

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[0023] Furthermore, if the third Doppler frequency fd3 cannot be obtained (for example, due to a failure of the third ground transceiver 23), the elements related to the unobtained third Doppler frequency fd3 and the Z-axis velocity W are removed, and the matrix in Equation 2 is reduced to the 2x2 matrix shown in Equation 7 below, in order to calculate the ground velocity Ug(U) in the port and starboard directions and the ground velocity Vg(V) in the bow and stern directions.

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[0024] Furthermore, in this ship speed measuring device 1, as shown in Figure 2, two of the three water-sensitive transceivers 31, 32, and 33 are connected to the axis (X-axis) connecting the port and starboard sides. The devices are arranged so that ultrasonic waves are transmitted symmetrically. That is, the second water-compatible transceiver 32 is arranged to transmit ultrasonic waves in the X-axis direction, and the first water-compatible transceiver 31 and the third The water-resistant transceiver 33 is arranged so that each ultrasonic wave is transmitted symmetrically with respect to the X-axis. Therefore, Declination angle Φ3w=-Declination angle Φ1w It can be expressed as follows.

[0025] Furthermore, if the Doppler frequencies fd1, fd2, and fd3 of the reflected waves received by any one of the three water-seeking transceivers 31, 32, and 33 cannot be obtained, the computing computer 4 assumes that the elements of the unobtainable Doppler frequencies fd1, fd2, and fd3 and the vertical water-seeking velocity Ww (Z-axis velocity W) do not exist (excludes them), and calculates the water-seeking velocity Vw (Y-axis velocity V) in the bow-stern direction and the water-seeking velocity Uw (X-axis velocity) in the port-starboard direction. Calculate the degree U.

[0026] That is, substitute the deflection angle Φ3w = -deflection angle Φ1w into equation 1 above. Then, if the second Doppler frequency fd2 cannot be obtained (for example, if the second transceiver 32 for water-to-water communication fails), remove the elements related to the second Doppler frequency fd2 that could not be obtained and the Z-axis velocity W in the same manner as above, reduce the matrix to a 2x2 matrix, and calculate the water-to-water velocity Vw(V) in the bow-stern direction using the following equation 8, which is the inverse matrix.

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[0027] Thus, even without obtaining the second Doppler frequency fd2, the water-to-water velocity Vw(V) in the bow-stern direction, which is important for measuring water-to-water velocity, can be obtained without being affected by the water-to-water velocity Uw (X-axis velocity U) in the port-starboard direction or the water-to-water velocity Ww (Z-axis velocity W) in the vertical direction. Similarly, the water-to-water velocity Uw(U) in the port-starboard direction can also be calculated from a matrix reduced to 2x2 in the same way, and can be obtained without error when the water-to-water velocity Ww(W) in the vertical direction is zero. If the water-to-water velocity Wg(W) in the vertical direction is not zero, an error will occur, but the influence of water-to-water velocity Ww(W) is small and the error is small. Furthermore, if the first Doppler frequency fd1 or the third Doppler frequency fd3 cannot be obtained, the elements related to the unobtained Doppler frequencies fd1 and fd3 and the Z-axis velocity W are removed in the same manner as described above, reducing the matrix to a 2x2 grid, and the water-to-water velocity Vw(V) in the bow-stern direction and the water-to-water velocity Uw(U) in the port-starboard direction are calculated.

[0028] In a ship speed measuring device 1 with this configuration, two ground-based transceivers 22 and 23 are arranged so that ultrasonic waves are transmitted symmetrically with respect to the axis connecting the bow and stern (Y-axis) when measuring ground speed. Therefore, the deflection angle Φ3g of the third ground-based transceiver 23 can be expressed by the deflection angle Φ2g of the second ground-based transceiver 22 (the number of parameters can be reduced). In other words, the deflection angle Φ3g can be expressed as π - deflection angle Φ2g.

[0029] Then, if the Doppler frequencies fd1, fd2, and fd3 of a single reflected wave cannot be obtained, the elements of the unobtainable Doppler frequencies fd1, fd2, and fd3, and the vertical ground velocity Wg(W), which is generally small (has little influence on the measurement), are excluded, and the ground velocity Ug(U) in the port and starboard directions and the ground velocity Vg(W) in the bow and stern directions are calculated. Thus, ground velocity Ug and Vg can be obtained using only the two Doppler frequencies fd1, fd2, and fd3, thereby reducing the risk of decreased measurement accuracy due to the loss of ultrasonic waves and reflected waves.

[0030] Furthermore, in measuring the velocity relative to water, ultrasonic waves are used symmetrically with respect to the axis connecting the port and starboard sides (X-axis). Since two water-compatible transceivers 31 and 33 are arranged so that the signal is transmitted, the deflection angle Φ3w of the third water-compatible transceiver 33 can be expressed by the deflection angle Φ1w of the first water-compatible transceiver 31 (the number of parameters can be reduced). In other words, the deflection angle Φ3w = -deflection angle Φ1w can be set.

[0031] Then, if the Doppler frequencies fd1, fd2, and fd3 of a single reflected wave cannot be obtained, the elements of the unobtained Doppler frequencies fd1, fd2, and fd3, and the vertical water-to-water velocity Ww(W), which generally has a small velocity (and therefore a small impact on the measurement), are excluded, and the water-to-water velocity Vw(V) in the bow-stern direction and the water-to-water velocity Uw(U) in the port-starboard direction are calculated. Thus, by using only the two obtained Doppler frequencies fd1, fd2, and fd3, the water velocity Vw and Uw can be acquired, reducing the risk of decreased measurement accuracy due to the loss of ultrasonic waves and reflected waves.

[0032] Although embodiments of this invention have been described above, the specific configuration is not limited to the embodiments described above, and any design changes, etc., that do not depart from the gist of this invention are also included. For example, in the embodiments described above, a case was described in which there are three ground-based transceivers 21, 22, and 23 and three water-based transceivers 31, 32, and 33, but four or more may be provided redundantly (as backup). Also, a case was described in which the ground speed and water speed of a ship S are measured with one ship speed measuring device 1, but depending on the type of ship S and the navigation environment, only one of them may be measured. [Explanation of symbols]

[0033] 1 Ship speed measuring device 21, 22, 23 Ground-to-ground transceivers (transceivers) 31, 32, 33 Water-resistant transceivers (transceivers) 4. Computational computer (computational means) S ship W1 underwater W2 Underwater Φ1g, Φ2g, Φ3g, Φ1w, Φ2w, Φ3w Declination θg, θw predetermined angle relative to the Z axis fd1, fd2, fd3 Doppler frequencies Vg: Ground speed in the bow-stern direction Ug: Ground speed in the port and starboard directions Wg: Vertical ground velocity Vw: Speed ​​relative to water in the bow-stern direction Uw: Speed ​​relative to water in the port and starboard directions Ww Vertical velocity relative to water

Claims

1. A ship speed measuring device comprising three transceivers, each arranged to transmit ultrasonic waves into the water from a ship and receive reflected waves from the seabed, and a calculation means for calculating the ground speed in the bow-stern direction, port-starboard direction, and vertical direction based on the Doppler frequencies of the reflected waves received by the three transceivers, Two of the three transceivers are arranged so that ultrasonic waves are transmitted symmetrically with respect to the axis connecting the bow and stern of the ship. If the Doppler frequency of the reflected wave received by any one of the three transceivers cannot be obtained, the calculation means calculates the ground speed in the bow-stern direction and the port-to-starboard direction, assuming that the elements of the Doppler frequency and the vertical ground speed are absent. A ship speed measuring device characterized by the following features.

2. A ship speed measuring device comprising three transceivers, each arranged to transmit ultrasonic waves into the water from a ship and receive reflected waves from the water, and a calculation means for calculating the water-relative speed in the bow-stern direction, port-starboard direction, and vertical direction based on the Doppler frequencies of the reflected waves received by the three transceivers, Two of the three transceivers are arranged so that ultrasonic waves are transmitted symmetrically with respect to the axis connecting the port and starboard sides. If the Doppler frequency of the reflected wave received by any one of the three transceivers cannot be obtained, the calculation means calculates the water velocity in the bow-stern direction and the port-to-starboard direction, assuming that the elements of the Doppler frequency and the vertical water velocity are absent. A ship speed measuring device characterized by the following features.

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