JP2554803B2 - Abnormal ship speed detection method and device - 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 and an apparatus for detecting whether or not the ship speed measured by a speedometer is abnormal.

[0002]

2. Description of the Related Art Ship speed information for ship tides (water speed), sea speed for seabed (ground speed), and ship speed information such as tides obtained from the difference between water speed and ground speed are widely used. Dead reckoning with a compass, for example,
NNS for adjusting engine output of ships and detecting positioning position
Input to navigation instruments such as S, correction of heading error of gyro compass, calculation of ship mileage by process integration distance meter, speed information to collision prevention device (ALPA), fin stabilizer angle adjustment, and chimney It is used for adjusting the opening area, etc. and is essential information for the ship operator.

As a method for detecting the water speed, a device that emits ultrasonic waves into the water from a ship and detects the water speed at the depth based on the Doppler shift amount of the reflected wave returning from the set depth (Doppler log). ), Or a device (electromagnetic log) that projects the sensor from the hull and obtains the water speed from the magnitude of the electromotive force generated between the electrodes facing each other due to the water flow. Can be detected based on the reflected waves returning from the sea bottom.

[0004]

However, since the Doppler log uses ultrasonic waves, erroneous detection is likely to occur when bubbles occur, and the reflection signal to water originally has a low S / N ratio. Therefore, the generation of air bubbles makes detection more difficult. Further, in the electromagnetic log, if air bubbles or wakes occur, an error will occur in the electromotive force.

If it is possible to identify a state where an accurate ship speed signal cannot be received due to the bubble generation or the like, the signal detected at this time may be removed, but the bubble generation occurs suddenly and intermittently. However, such identification is impossible, and as a result of capturing an abnormal ship speed signal, the operation of each device systematically configured on the ship is immeasurablely hindered. For example, it may happen that the engine output is judged to be abnormal even though it is normal, and an alarm is output, or the fin stabilizer suddenly changes its angle while the vessel is traveling at a constant speed and the hull leans abnormally. There was a risk that it would lead to a serious accident.

The present invention has been made in order to solve the above-mentioned problems, and determines whether or not the measured ship speed is normal, and outputs an alarm if abnormal, or another measurement system. It is an object of the present invention to provide an abnormal ship speed detection method and device that can be backed up by the signal obtained in step 1.

[0007]

A method for detecting abnormal ship speed according to the first aspect of the present invention (claim 1) is a method for detecting whether the ship speed measured by a speedometer is abnormal or not. The variances K ₁ and K ₂ showing the respective response characteristics of the ship speed (D ₁ ) measured by the meter and the ship speed (D ₂ ) obtained by another measurement system are obtained, and the ratio of the two dispersions is used to determine one ship By making the response characteristics of both ship speeds uniform by exponentially smoothing the speed (D ₂ ), the ship speed difference between them is obtained, and when the ship speed difference exceeds a predetermined threshold value, the ship speed is (D ₁ )
Is determined to be abnormal.

As shown in FIG. 1, the abnormal ship speed detecting device (claim 2) relating to the method for detecting abnormal ship speed according to the first aspect of the present invention determines whether the ship speed measured by the speedometer is abnormal, as shown in FIG. An abnormal ship speed detection device capable of detection, comprising a ship speed signal input section (1) for receiving a ship speed signal measured by the speedometer and a ship speed signal for receiving a ship speed signal obtained by another measuring system. Vessel speed input to the input section (2) and the vessel speed signal input sections (1) and (2) respectively
Dispersion detectors (3) and (4) for detecting dispersions K ₁ and K ₂ showing respective response characteristics of (D ₁ ) and ship speed (D ₂ ),
An average exponent operation for obtaining an average exponent R ₁ used for exponential smoothing for approximating _one ship speed (D ₂ ) to the response characteristic of the other ship speed (D ₁ ) from the ratio of the variances K ₁ and K _2. Part (7),
An exponential smoothing section (8) for exponentially smoothing the ship speed (D ₂ ) using the average exponent R ₁ to obtain the ship speed (D ₃ ), a ship speed (D ₁ ) and a ship speed
A ship speed difference calculation unit (9) for obtaining a ship speed difference (DD) from (D ₃ ),
When the ship speed difference (DD) is less than or equal to the threshold value, the ship speed (D ₁ ) is normal, and when the ship speed difference (DD) exceeds the threshold value, the ship speed is
It is characterized by including a signal determination section (12) for determining (D ₁ ) as abnormal.

The method for detecting an abnormal ship speed according to the second aspect of the present invention (claim 5) is a method for detecting whether the ship speed measured by a speedometer is abnormal or not, and the dispersion K measured by the speedometer is used. boat speed with ₁ (D _1), in order to approximate the signal system having a different dispersion K _3, and exponential smoothing with K ₁ / K ₃ values, boat speed with variance K ₂ obtained by another measuring system In order to approximate (D ₂ ) to a signal system having the dispersion K ₃ , the response characteristics of both ship speeds are made uniform by exponentially smoothing with the K ₂ / K ₃ value, and the ship speed difference between them is calculated. When the ship speed difference exceeds a predetermined threshold value, the ship speed (D ₁ ) is determined to be abnormal.

As shown in FIG. 3, the abnormal ship speed detecting device (according to claim 6) relating to the method for detecting abnormal ship speed according to the second aspect of the present invention, as shown in FIG. An abnormal ship speed detection device capable of detection, comprising a ship speed signal input section (21) for receiving a ship speed (D ₁ ) signal having a dispersion K ₁ measured by the speedometer, and a separate measurement system. Vessel speed with dispersion K ₂ obtained
Ship speed signal input section (22) for receiving the signal of (D ₂ ) and dispersion K ₁
Of boat speed to (D _1), in order to exponential smoothing the signal system having a different dispersion K _3, boat speed by exponential smoothing with an average index _{S 2 (= K 1 / K} 3) (D 1 ' ) Output exponential smoothing part (23)
If, boat speed by exponential smoothing with a boat speed of dispersion K ₂ a (D _2), in order to exponential smoothing the signal system with the dispersion K _3, the average index _{S 3 (= K 2 / K} 3) (D ₂ ') exponential smoothing unit for outputting (24), boat speed (D _1' boat speed difference between) Funesoku and (D ₂ ')
The ship speed difference calculation unit (25) for obtaining (DD) and the ship speed difference (D
When D) is less than or equal to the threshold value, the ship speed (D ₁ ) is normal, and when the ship speed difference (DD) exceeds the threshold value, the ship speed (D ₁ ) is abnormal. (26) is provided.

As shown in FIG. 5 (claim 8), the ship speed (D ₁ ') from the exponential smoothing section (23) is latched and output, or the ship speed (D ₁ ') is output. By further including the latch / through switching unit (29) for outputting as it is, the latch / through switching unit (29) determines that the ship speed (D ₁ ) is normal by the signal determination unit (26). At this time, the ship speed (D ₁ ') from the exponential smoothing section (23) is output as it is,
When (D ₁ ) is determined to be abnormal, the normal ship speed (Dh ′) latched last time can be output.

[0012]

In order to judge whether the ship speed detected by the speedometer is normal or not and to make a backup when it is judged to be abnormal, two measuring systems are required. In the above-mentioned Doppler log, there are erroneous detections due to the measurement environment (bubble generation, S / N ratio and motion of the ship), and in order to back up this, it is necessary to prepare another measurement system (the same measurement system is used). If both are provided, false detections will occur on both sides.)

FIG. 9 shows the ship speeds D ₁ (solid line) and D ₂ (thin line) measured by the ship speedometer 1 and another kind of speedometer 2 when the ship speed changes stepwise. In this way, if the types of ship speedometers are different, the response characteristics differ between the two due to variations in the detected speed and the difference in the detected response time, so it is not possible to determine an abnormality in the ship speed only by comparing the ship speeds of the two. . In order to do this, the ship speed D ₂ must be approximated to the ship speed D ₁ (actually, a response approximation curve (broken line) of this ship speed D ₁ ) before the two can be compared.

FIG. 10 is a diagram showing the variations in the ship speeds D ₁ and D ₂ in FIG. 9, and FIG. 11 is a diagram showing the variations (dispersion) in FIG. 9 as a frequency distribution. This FIG.
As can be seen from the above, the characteristics of the ship speeds D ₁ and D ₂ in FIG. 9 can be expressed by dispersion. Therefore, in the present invention, both ship speeds D
By unifying (smoothing) the dispersion values for ₁ and D ₂ , the response characteristics of both ship speeds are approximately equalized.

In the first aspect of the present invention (claim 1), the dispersion K ₁ showing the respective response characteristics of the ship speed (D ₁ ) measured by the ship speed meter and the ship speed (D ₂ ) obtained by another measuring system. , K ₂ are obtained, and one ship speed (D ₂ ) is exponentially smoothed by using the ratio of both variances (this exponential smoothing will be described in detail in an embodiment), so that the response characteristics of both ship speeds are made uniform. Then, the ship speed difference is obtained, and when the ship speed difference exceeds a predetermined threshold value, the ship speed (D ₁ ) is determined to be abnormal.

According to the second aspect of the present invention (claim 6), the ship speed (D ₁ ) measured by a speedometer with known dispersion K ₁ is exponentially smoothed to a signal system having another dispersion K ₃ to obtain the dispersion K 1. _The ship speed (D ₂ ) obtained by another measurement system of which ₂ is known is exponentially smoothed to the signal system having the dispersion K ₃ to make the response characteristics of both ship speeds uniform.

[0017]

FIG. 2 is a control block diagram showing an embodiment of the abnormal ship speed detection device of the present invention. Numerals 1 and 2 are ship speed signal input parts. A ground speed signal obtained by a speedometer using ultrasonic waves, for example, is inputted to the input part 1 as a ship speed D _1, and the input part 2 is supplied with a ship speed signal. As D ₂ , a ground speed signal from a navigation device, which is a measurement system different from the ultrasonic system, is input. The navigation device is a device that obtains position information and ground speed based on information from navigation devices such as GPS (Global Positioning System) and Loran C.

[0018] 3 samples the data of a predetermined number from the signal of the boat speed D _1, a dispersion detecting unit for determining the variance K ₁ from those data representing the signal characteristics of the ship speed D _1, 4
Is a dispersion detecting unit for determining the variance K ₂ representing the signal characteristics of the ship speed D ₂ in the same manner from the signals of the boat speed D _2, each of the dispersion K _1, K ₂ is stored in the memory 5 and 6 . 7 is the ratio (K ₁ / K ₂ ) of the variances K ₁ and K ₂ , and the exponential smoothing unit 8 averages the variations at the ship speed D _{2 into} the variations at the ship speed D ₁ (here, exponential smoothing is used). ) Is an average exponent calculation unit for obtaining an average exponent R ₁ used when
, By exponential smoothing variations in ship speed D ₂ with this average index R _1, obtaining the boat speed D ₃ which approximates the response characteristic of the ship speed D _1.

The averaging method is, for example, a simple moving average. If the K ₁ / K ₂ ratio is 0.5, boat speed D ₂
In order to suppress the variation in 2 to 1/2, the variation is reduced to 1/2 by taking the average of the past two data (the average of the variations in the past two data).
And get the data. This will be described in detail. If the initial ship speed data is 10 knots and the next input data is 5 knots, then there will be 10−5 = 5 knots between them. On the other hand, the average of these two ship speeds is 7.5 knots. Based on these 7.5 knots, there is a difference of -2.5 knots from the first ship speed and a difference of +2.5 knots from the next ship speed. Therefore, this addition average value (7.5 The knots are those in which the above variation (5 knots) is suppressed to 1/2. With this method, K ₁ / K ₂
When the ratio is 1 / N, a memory for storing N pieces of data is required, and since the N value must be an integer,
It is difficult to deal with the characteristics of variations that change from time to time.

Therefore, in the present invention, the above exponential smoothing method is used. In this exponential smoothing method, the average index R (≦ 1) which is the K ₁ / K ₂ ratio for the sampling data d of the ship speed D ₂
Data dn output from the exponential smoothing unit 8 when
Calculates data dn based on dn = dn _-1 * R + d * (1-R). dn _-1 is the previously calculated data.

The exponentially smoothed ship speed D ₃ consisting of the data dn thus calculated comes to be approximately similar to the response characteristic of the ship speed D ₁ . 9 is a ship speed difference calculator for calculating the ship speed D ₁ and Funesoku D ₃ and the ship speed difference _{DD (= D 1 -D 3)} .

A latch circuit 10 latches the boat speed difference DD from the boat speed difference calculation unit 9 while the boat speed difference DD is determined to be normal according to the determination result of the signal determination unit 12 described later. . 11 is a ship speed difference D latched by the latch circuit 10.
This is a ship speed calculation unit that calculates a ship speed difference D ₄ between D and the ship speed D ₃ . The signal determination unit 12 determines that the ship speed difference DD is the threshold value S ₁
It is determined whether the ship speed D ₁ is normal or abnormal depending on whether or not the speed is less than. Reference numeral 13 denotes a changeover switch, which switches the signal supplied to the exponential smoothing unit 14 from the ship speed D ₁ to the ship speed difference D ₄ calculated by the ship speed calculation unit 11 when it is determined that the ship speed D ₁ is abnormal. . The exponential smoothing unit 14 exponentially smoothes the input value using a fixed average exponent, and supplies the input value to the ship speed output unit 15. Reference numeral 16 is an alarm device, which outputs an alarm when it is determined that the ship speed D ₁ is abnormal.

The operation of the apparatus having the above configuration will be described below. The ship speeds D ₁ and D ₂ input to the ship speed signal input units 1 and ₂ are
The variance detectors 3 and 4 detect the variances K ₁ and K _{2 in} order to know the signal characteristics of those signals, and store them in the memories 5 and 6, respectively. In the average index calculation unit 7, the average index R ₁ is obtained from the ratio of the variances K ₁ and K ₂ , and in the index smoothing unit 8, the ship speed D ₂ is index smoothed based on this average index R _1. , A ship speed D _{3 which} is approximately similar to the response characteristic of the ship speed D ₂ is obtained.

The ship speed difference calculating unit 9 obtains the ship speed D ₁ , the ship speed D ₃ and the ship speed difference DD, and the ship speed difference DD is less than the threshold value S ₁ in the signal judging unit 12. It is determined whether or not there is, and if DD ≦ S ₁ , it is determined that the boat speed D ₁ is normal, and this boat speed D ₁ is supplied to the exponential smoothing unit 14 via the changeover switch 13. On the other hand, DD> S ₁ ,
If it is determined that the boat speed D ₁ is abnormal, the changeover switch 13 is switched and the alarm sound is output from the alarm device 16. Further, since the latch circuit 10 stops taking in the ship speed difference DD from the ship speed difference 9, the latch circuit 10 latches the normal ship speed difference (referred to as DD ') immediately before the abnormality. It will be. In the ship speed calculation unit 11, the ship speed difference DD ′ under normal conditions is calculated from the exponentially smoothed ship speed D ₃ described above.
And the ship speed D ₄ is calculated. The boat speed D ₄ is supplied to the exponential smoothing unit 14 via the changeover switch 13, where it is exponentially smoothed by a fixed average exponent and supplied to the boat speed output unit 15.

After that, in the signal judging section 12, DD <
When it is determined to be S _1, and the ship speed D ₁ returns to normal, the changeover switch 13 is immediately switched, and the exponential smoothing unit 14 is supplied with the ship speed D ₁ . Thus, when the ship speed D ₁ becomes an abnormal value or is missing, the ship speed D ₄ created based on the ship speed D ₂ from the navigation device instead of the ship speed D ₁
Is supplied as a backup signal.

In the above embodiment, the ground speed is input to the ship speed signal input unit 1 as the ship speed D ₁ , but it may be the water speed, or the ship speed D ₂ to the ship speed signal input unit ₂ may be used. Although the ground speed from the navigation device was input, even if it is the ground speed or the water speed obtained by another ultrasonic speedometer, by matching the response characteristics of both signals, one signal Can be backed up with the other signal as well.

Further, in the above embodiment, the dispersion of the signals detected by the ship speedometer and the navigation device, that is, the response characteristic is unknown, but the ship speedometer is a specific Doppler speedometer, The device is also specific, and when the response characteristics of those detection signals are known, the dispersion detection units 3 and 4 in FIG. 2 are not necessary, and the ship speed abnormality detection device in this case is a second invention. It is shown in FIG.

In order to approximate the ship speed signal D ₁ having a known dispersion (K ₁ ) input to the ship speed signal input unit 21 to a signal system having another dispersion K ₃ , the exponential smoothing unit 23. , Average exponent S ₂ (= K ₁ / K ₃ ) is used for exponential smoothing. On the other hand,
In order to approximate the ship speed signal D ₂ having a known dispersion (K ₂ ) input to the ship speed signal input unit 22 to a signal system having the dispersion K ₃ , the exponent smoothing unit 24 uses the average exponent S. ₃ (= K
Exponential smoothing with ₂ / K ₃ ). The ship speeds D ₁ ′ and D ₂ ′ whose response characteristics are aligned in this way are calculated by the ship speed difference calculation unit 2
5 in boat speed difference _{DD (= D 1 '-D 2} ') is determined, boat speed D ₁ on whether the boat speed difference DD exceeds this or threshold S ₁ or less'
Is determined to be normal or abnormal, and as shown in FIG. 7, when it is normal (when D ₁ '≧ D ₂ ' -S ₁ ), the changeover switch 2
7 outputs the normal ship speed D ₁ ′, but when the ship speed D ₁ ′ is abnormal (when D ₁ ′ <D ₂ ′ −S ₁ ), the ship speed D ₁ ′ is replaced with the ship speed D ₁ ′. D ₂ 'is output. If the ship speed D ₁ 'returns to normal,
This ship speed D ₁ 'is output again.

FIG. 6 shows another embodiment of the second aspect of the invention, which is different from FIG. 4 in that a latch / through switching section 29 is provided instead of the changeover switch 27, and the ship speed D ₁ ' When the ship speed D ₁ 'is normal, the ship speed D ₁ ' is output in real time, but when the ship speed D ₁ 'is abnormal, as shown in FIG.
Outputs "boat speed Dh during normal 'latched have the boat speed D ₁ immediately before.

A circuit example of the latch / through switching unit 29 is shown in FIG. This is composed of a shift register 51 and a changeover switch 52.
Register 51 for latching the ship speed D ₁ ′ by the shift clock output every time the ship speed D ₁ is determined to be normal by
A and a register 51B for receiving the data latched in the register 51A. The changeover switch 52 is
While the ship speed D ₁ is determined to be normal, the ship speed D ₁ 'is output in real time. On the other hand, when the ship speed D ₁ is determined to be abnormal, the previous latch stored in the register 51B is stored. Outputs data, that is, normal data.

In the apparatus of FIGS. 4 and 6, both ship speed signals D ₁ and D ₂ are exponentially smoothed and converted into a signal system having a common response characteristic, but one ship speed (for example, D ₁ ) May be exponentially smoothed with a predetermined average exponent only for the ship speed D ₁ so that the response characteristic of) matches the other ship speed D ₂ .

[0032]

As described above, according to the present invention, the ship speed D
Separately from ₁ , input the ship speed D ₂ from the navigation system, etc., determine the difference between both ship speeds after aligning the response characteristics of both ship speeds, and determine whether the ship speed difference falls below the threshold value. It is possible to determine whether D ₁ is normal or abnormal. Therefore,
According to the present invention, it is possible to eliminate an abnormal ship speed, so that it is possible to eliminate a problem that an abnormal ship speed signal is taken in, which hinders navigation of a ship. Further, when an abnormality is detected in the boat speed D _1, can be backed up by another ship speed at the normal time of the previous measurement boat speed is created based on the ship speed D ₂ obtained in system D ₄ or boat speed D ₁ Therefore, even if the detection of the ship speed D ₁ is temporarily interrupted, the accurate ship speed can be continuously output.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of an abnormal ship speed detection device according to a first invention.

FIG. 2 is a control block diagram showing an embodiment of the first invention.

FIG. 3 is a diagram corresponding to claims of the abnormal ship speed detection device of the second invention.

FIG. 4 is a control block diagram showing an embodiment of a second invention.

FIG. 5 is a diagram corresponding to claims of the abnormal ship speed detection device according to claim 8;

FIG. 6 is a control block diagram showing another embodiment of the second invention.

7 is a time chart showing an output signal in the device of FIG.

8 is a time chart showing an output signal in the device of FIG.

FIG. 9 is a diagram showing the difference in response characteristics at the detected ship speed due to the difference in the speedometer.

FIG. 10 is a diagram illustrating variations in ship speed in FIG.

FIG. 11 is a diagram showing the variation of FIG. 10 with a frequency distribution.

FIG. 12 is a detailed view of a latch / through switching unit in FIG.

[Explanation of symbols]

 1 Ship Speed Signal Input Section 2 Ship Speed Signal Input Section 3 Variance Detection Section 4 Variance Detection Section 5 Memory 6 Memory 7 Mean Index Calculation Section 8 Exponential Smoothing Section 9 Ship Speed Difference Calculation Section 10 Latch Circuit 11 Ship Speed Calculation Section 12 Signal Judgment Part 13 Changeover switch 14 Exponential smoothing part 15 Ship speed output part 16 Alarm device 23 Exponential smoothing part 24 Exponential smoothing part 29 Latch / through switching part

Claims (10)

(57) [Claims] 1. A method for detecting whether or not the ship speed measured by the ship speed meter is abnormal, which comprises measuring the ship speed (D ₁ ) measured by the ship speed meter,
The variances K ₁ and K ₂ showing the respective response characteristics of the ship speed (D ₂ ) obtained by another measurement system are obtained, and one ship speed is calculated using the ratio of both dispersions.
By exponentially smoothing (D ₂ ), the response characteristics of both ship speeds are made uniform, and the ship speed difference between them is calculated. When the ship speed difference exceeds a predetermined threshold value, the ship speed ( A method for detecting an abnormal ship speed, characterized in that D ₁ ) is judged to be abnormal. 2. An abnormal ship speed detecting device capable of detecting whether or not the ship speed measured by the ship speed meter is abnormal, the ship speed signal input unit receiving a ship speed signal measured by the ship speed meter.
(1) and the ship speed signal input section that receives the ship speed signal obtained by another measurement system (2)
If, boat speed signal input portion (1) and the boat speed, which is input to the (2) (D ₁₎ and Funesoku (D ₂₎ of each detected dispersing detecting dispersion K ₁ and K ₂ which shows the response characteristics Parts (3) and (4)
And an average index R ₁ used for exponential smoothing for approximating _one ship speed (D ₂ ) to the response characteristics of the other ship speed (D ₁ ) from the ratio of the variances K ₁ and K _2. An exponent calculation unit (7), an exponential smoothing unit (8) for exponentially smoothing the ship speed (D ₂ ) using the average exponent R ₁ to obtain a ship speed (D ₃ ), and a ship speed (D ₁ ). A ship speed difference calculation unit (9) for obtaining a ship speed difference (DD) from the ship speed (D ₃ ), and when the ship speed difference (DD) is less than or equal to a threshold value, the ship speed (D ₁ ) is normal, When the ship speed difference (DD) exceeds the threshold value, the ship speed
An abnormal ship speed detection device, comprising: a signal determination unit (12) for determining (D ₁ ) as abnormal. 3. A latch for latching the ship speed difference (DD) output from the ship speed difference calculation unit (9) while the signal judging unit (12) judges that the ship speed (D ₁ ) is normal. A circuit (10) and a ship speed calculator for calculating the ship speed (D ₄ ) by subtracting the ship speed difference (DD ′) latched by the latch circuit (10) from the ship speed (D ₃ ).
(11) and the ship speed (D ₁ ) based on the judgment result of the signal judging unit (12).
If the ship speed is normal, this ship speed (D ₁ ) is output. If the ship speed (D ₁ ) is abnormal, the changeover switch (1) that outputs the ship speed (D ₄ ) is output.
The abnormal ship speed detection device according to claim 2, further comprising: 3). 4. An alarm device (16) for outputting an alarm, and when the signal determination unit (12) determines that the ship speed (D ₁ ) is abnormal, the alarm device (16) outputs an alarm. The abnormal ship speed detection device according to claim 2 or claim 3. 5. A method for detecting whether or not the ship speed measured by the ship speed meter is abnormal, wherein the ship speed (D ₁ ) having the dispersion K ₁ measured by the ship speed meter is replaced by another dispersion K ₃ . In order to approximate the signal system having the same, the ship speed (D ₂ ) having the variance K ₂ obtained by another measurement system is exponentially smoothed by the K ₁ / K ₃ value and approximated to the signal system having the variance K ₃ . Therefore, after the response characteristics of both ship speeds are made uniform by exponentially smoothing the K ₂ / K ₃ value, the ship speed difference between them is obtained, and when the ship speed difference exceeds a predetermined threshold value, the ship speed is A method for detecting an abnormal ship speed, characterized in that (D ₁ ) is judged to be abnormal. 6. An abnormal ship speed detecting device capable of detecting whether or not the ship speed measured by a ship speed meter is abnormal, wherein a ship speed (D ₁ ) having a dispersion K ₁ measured by the ship speed meter is detected. A ship speed signal input section (21) for receiving a signal, a ship speed signal input section (22) for receiving a ship speed (D ₂ ) signal having a dispersion K ₂ obtained by another measurement system, and a ship with a dispersion K ₁ fast the (D _1), in order to approximate the signal system having a different dispersion K _3, and outputs the exponential smoothing with an average index _{S 2 (= K 1 / K} 3) ship speed a (D ₁ ') index smoothing unit (23), boat speed of dispersion K ₂ a (D _2), so as to approximate the signal system with the dispersion K _3, and exponential smoothing with an average index _{S 3 (= K 2 / K} 3) boat speed (D ₂ ') exponential smoothing unit for outputting (24) and boat speed (D _1') and Funesoku (D ₂ ') boat speed difference between obtaining the (DD) boat speed difference calculation unit (25 ), And if the ship speed difference (DD) is less than or equal to the threshold value,
(D ₁ ) is normal, and when the ship speed difference (DD) exceeds a threshold value, a signal determination unit (26) for determining the ship speed (D ₁ ) as abnormal is provided. Ship speed detection device. 7. When the ship speed (D ₁ ) is normal based on the judgment result of the signal judging unit (26), the ship speed (D ₁ ') is outputted from the exponential smoothing unit (23), The abnormal ship speed detecting device according to claim 6, further comprising a changeover switch (27) for outputting the ship speed (D ₂ ') from the exponential smoothing section (24) when the speed (D ₁ ) is abnormal. 8. A latch / through switching unit (29) for latching and outputting the ship speed (D ₁ ') from the exponential smoothing unit (23) or for outputting the ship speed (D ₁ ') as it is. Further, the latch / through switching section (29) is provided with the signal judging section (2).
According to 6), when the ship speed (D ₁ ) is determined to be normal, the ship speed (D ₁ ') from the exponential smoothing section (23) is directly output,
7. The abnormal ship speed detection device according to claim 6, wherein when the ship speed (D ₁ ) is determined to be abnormal, the previously latched normal ship speed (Dh ') is output. 9. An alarm device (16) for outputting an alarm, and when the signal determination unit (26) determines that the ship speed (D ₁ ) is abnormal, the alarm device (16) outputs an alarm. The abnormal ship speed detection device according to any one of claims 6 to 8. 10. A boat speed measuring system comprising two types of boat speed gauges and the abnormal boat speed detecting device according to any one of claims 2 to 4 or 6 to 9.