JP6412642B2 - Apparatus, system, method, and program for specifying ship speed against water - Google Patents

Description

  The present invention relates to a technique for specifying the speed of a watercraft.

  There has been proposed a technique for correcting the measured ship speed when the ship speed measured using the ship speedometer shows an abnormality. For example, Patent Document 1 discloses a first ship speed (ground ship speed or water ship speed) measured by a ship speedometer using ultrasonic waves and a navigation device using GPS (Global Positioning System) or the like. When the measured second ship speed (ground ship speed) deviates, a mechanism using an estimated value of the ship speed calculated from these two kinds of ship speeds instead of the first ship speed is proposed. ing. Specifically, a third boat speed obtained by exponentially smoothing the second boat speed using the average index calculated from the difference between the variance of the first boat speed and the variance of the second boat speed is calculated. When the difference between the first boat speed and the third boat speed exceeds the threshold value, the first boat speed is determined to be abnormal. When it is determined that the first boat speed is abnormal, the fourth boat speed calculated using the second boat speed is used instead of the first boat speed.

JP-A-5-72335

  As a ship speedometer for measuring the speed of water against water, an electromagnetic type, a rotor blade type, a pressure type, an acoustic type, and the like are known. For example, acoustic ship speedometers that have been widely used in recent years emit a sound wave from a ship toward the bottom of the water, and the difference between the frequency of the emitted sound wave and the frequency of the reflected wave of the sound wave reflected by a floating object in water. Based on this, calculate the relative speed of the ship to the water.

  The ship speed against water measured by the ship speedometer sometimes shows an abnormal value. For example, when an acoustic ship speedometer receives a reflected wave reflected by a bubble rising in water, it cannot calculate a correct water speed and outputs an abnormal value. Non-acoustic ship speedometers sometimes show abnormal values because of noise on signals used for each measurement.

  In the mechanism described in Patent Document 1, an abnormality in the ship speed against water measured by the ship speedometer is corrected using the ship speed measured by GPS or the like. In order for this correction to be meaningful, the measured values for water speed and ground speed need to follow the same statistical distribution. Therefore, if the ship speed is different from the ground speed for a long time due to reasons such as the ship riding in the ocean current, the speed of the water speed used when the measured value of the speed of water shows an abnormality. The correction value does not indicate actual water speed.

  In view of the above circumstances, an object of the present invention is to provide a means for specifying a reasonable speed of watercraft.

In order to solve the above problems, the present invention relates to a ship propeller rotation speed measured within a first period and an anti-ship of the ship measured within a second period different from the first period. The first and second propeller slips in the first period and the second period are substantially the same using the speed and the propeller rotation speed of the ship measured in the second period . An apparatus is provided that includes a specifying unit that specifies the speed of the ship against water within a period.

  In the above apparatus, a difference between a change in the propeller rotation speed of the ship measured within the first period and a change in the speed of the ship with respect to water measured during the first period is determined. A determination unit that determines whether or not the speed of the ship against the water measured within the first period is abnormal based on the index value indicated; and the ship measured during the first period When the determination unit determines that the speed of the watercraft is not abnormal, the speed of the watercraft of the ship measured within the first period is output, and the speed of the ship measured within the first period is output. A configuration in which, when the determination unit determines that the ship speed is abnormal, the output unit outputs the ship speed of the ship within the first period specified by the specifying unit. It may be adopted.

  In the above-described device, the determination unit may determine whether the determination unit has a predetermined time length preceding the first period or a predetermined time length following the first period. A configuration is adopted in which the time period when the measured water speed of the ship is not abnormal is determined as the second period, and the water speed of the ship within the first period is specified. May be.

  Further, in the above apparatus, the specifying unit is a period in which the ship encounters a weather or sea condition that is the same as or similar to a weather or sea condition that the ship has encountered in the first period, and the determination unit includes A configuration is adopted in which the time period when the measured water speed of the ship is not abnormal is determined as the second period, and the water speed of the ship within the first period is specified. May be.

Further, in the above apparatus, the measured ground using the ship's ground speed measured within the period for each of a plurality of periods and the ship's water speed measured during the period. The relationship between the ship speed and the measured water speed is specified, and the measured value of the ship's speed relative to the water so that the specified relation is a relationship indicated by a straight line with a slope passing through the origin. A configuration in which a correction unit that corrects the above is provided may be employed.

Further, in the above device, for each of a plurality of periods, the ground speed of the ship measured within the period and the weather or sea condition that the ship encountered within the period are estimated within the period. Using the estimated anti-water vessel speed that is the anti-water vessel speed of the vessel and the anti-water vessel speed of the vessel measured during the period, the estimated anti-water vessel speed and the measured anti-water vessel speed A configuration is adopted that includes a correction unit that corrects the measured value of the ship's speed against water so that the specified relationship becomes a relationship indicated by a straight line with a slope passing through the origin. May be.

Further, the present invention relates to the measured ground ship speed using the ship's ground speed measured during the period for each of the plurality of periods and the ship's water speed measured during the period. And the measured ship speed against water, and the measured relation of the ship's speed against water is corrected so that the identified relation is indicated by a straight line with a slope of 1 passing through the origin. There is provided an apparatus including a correcting unit.

Further, the present invention relates to each of a plurality of periods, and the ship in the period estimated based on the ship's ground speed measured in the period and the weather or sea condition encountered by the ship in the period. Using the estimated anti-watercraft speed that is the anti-watercraft speed of the ship and the anti-watercraft speed of the ship measured during the period, the relationship between the estimated anti-watercraft speed and the measured anti-watercraft speed And an apparatus including a correction unit that corrects the measured value of the speed of the ship against water so that the specified relationship is a relationship indicated by a straight line with a slope passing through the origin .

Further, the present invention includes a step of measuring the propeller rotation speed of the ship within a first period, and a step of measuring the propeller rotation speed of the ship within a second period different from the first period; The step of measuring the speed of the ship against water in the second period, the propeller rotation speed of the ship measured in the first period, and the second period were measured. The propeller slips of the first period and the second period are substantially the same using the propeller rotation speed of the ship and the speed of the ship with respect to water measured within the second period. Determining the speed of the vessel against water within the first time period in some cases .

Further, the present invention relates to each of a plurality of periods, a step of measuring a ship's ground speed within the period, a step of measuring a water speed of the ship within the period, and the measured ground ship The step of identifying the relationship between the speed and the measured speed of the watercraft, and the measurement of the speed of the watercraft for the watercraft so that the identified relationship is a relationship indicated by a straight line with an inclination passing through the origin. And correcting the value.

Further, the present invention relates to each of a plurality of periods, the step of measuring the ship's ground speed within the period, the measured ground speed, and the weather or sea condition encountered by the ship during the period. A step of estimating a water speed of the ship within the period, a step of measuring a water speed of the ship within the period, the estimated water speed and the measured water ship A step of specifying a relationship with speed, and a step of correcting a measured value of the vessel's speed against water so that the specified relationship becomes a relationship indicated by a straight line with a slope passing through the origin. Provide a method.

Further, the present invention provides a computer with a propeller rotation speed of a ship measured within a first period, a water speed of the ship measured within a second period different from the first period, and In the first period when the propeller slips in the first period and the second period are substantially the same, using the propeller rotation speed of the ship measured in the second period. A program for executing a process for specifying the speed of the ship with respect to water is provided.

In the present invention, the computer uses the ship's ground speed measured during the period for each of the plurality of periods and the ship's water speed measured during the period. The process of identifying the relationship between the ship speed against the ground and the measured speed of the watercraft , and the watercraft of the ship so that the identified relation is a relationship indicated by a straight line with a slope passing through the origin. A program for executing a process of correcting a measurement value of speed is provided.

Further, the present invention relates to a computer with respect to each of a plurality of periods, within the period estimated based on the ship's ground speed measured during the period and the weather or sea condition encountered by the ship during the period. The estimated anti-water vessel speed and the measured anti-water vessel speed using the estimated anti-water vessel speed that is the anti-water vessel speed of the vessel and the anti-water vessel speed of the vessel measured during the period. And a process of correcting the measured value of the ship's speed relative to the water so that the specified relation becomes a relation indicated by a straight line with a slope passing through the origin . A program is provided.

Further, the present invention provides a computer with a propeller rotation speed of a ship measured within a first period, a water speed of the ship measured within a second period different from the first period, and In the first period when the propeller slips in the first period and the second period are substantially the same, using the propeller rotation speed of the ship measured in the second period. The computer-readable recording medium which records continuously the program for performing the process which specifies the water-vessel speed of the said ship in is provided.

In the present invention, the computer uses the ship's ground speed measured during the period for each of the plurality of periods and the ship's water speed measured during the period. The process of identifying the relationship between the ship speed against the ground and the measured speed of the watercraft , and the watercraft of the ship so that the identified relation is a relationship indicated by a straight line with a slope passing through the origin. Provided is a computer-readable recording medium for continuously recording a program for executing processing for correcting a speed measurement value.

Further, the present invention relates to a computer with respect to each of a plurality of periods, within the period estimated based on the ship's ground speed measured during the period and the weather or sea condition encountered by the ship during the period. The estimated anti-water vessel speed and the measured anti-water vessel speed using the estimated anti-water vessel speed that is the anti-water vessel speed of the vessel and the anti-water vessel speed of the vessel measured during the period. And a process of correcting the measured value of the ship's speed relative to the water so that the specified relation becomes a relation indicated by a straight line with a slope passing through the origin . A computer-readable recording medium for continuously recording a program for the purpose is provided.

  According to the present invention, a reasonable water speed is specified.

It is a figure which shows the whole structure of the anti-watercraft speed specific system which concerns on one Embodiment. It is a figure which shows the hardware constitutions of the data processor which concerns on one Embodiment. It is a figure which shows the function structure of the data processor which concerns on one Embodiment. It is the graph which plotted the combination of the measurement ship water speed and ground ship speed utilized by the data processor which concerns on one Embodiment. It is the graph which plotted the combination of the measurement ship water speed and ground ship speed utilized by the data processor which concerns on one Embodiment. It is the figure which showed the flow of the process which the data processor which concerns on one Embodiment performs. It is the graph which showed the time series change of the data utilized by the data processor concerning one embodiment. It is a figure which shows the whole structure of the anti-watercraft speed specific system which concerns on one modification. It is a figure which shows the function structure of the data processor which concerns on one Embodiment. It is a figure which shows the function structure of the server apparatus which concerns on one Embodiment.

1. Configuration FIG. 1 is a diagram showing an overall configuration of a watercraft speed identification system 1 according to the present embodiment. The anti-water vessel speed specifying system 1 is a system for specifying the anti-water vessel speed of a vessel and is mounted on the vessel. The anti-water vessel speed specifying system 1 includes an anti-water vessel speed meter 11, an anti-water vessel speed meter 12, a tachometer 13, and a data processing device 14.

  The anti-ship speedometer 11 measures the speed of the ship against the water. The anti-ship speedometer 11 is an acoustic speedometer, for example, but the method is not limited to the acoustic type, and may be an electromagnetic type.

  The ground speedometer 12 measures the speed of the ship against the ground. The ground speedometer 12 measures the speed of the ground ship using a satellite positioning system such as GPS, but the method is not limited to that using the satellite positioning system, and may be a Doppler radar or the like.

  The tachometer 13 measures the propeller rotation speed per unit time of the ship (hereinafter simply referred to as “propeller rotation speed” in the present application). The tachometer 13 may measure the number of revolutions of the propeller shaft, or measure the number of revolutions of another member having a strong correlation with the number of revolutions of the propeller shaft (for example, the number of revolutions of the engine driving the propeller). The propeller rotational speed may be measured by The tachometer 13 is, for example, an electric tachometer. However, the method is not limited to an electric type, an optical type, a digital type, or an analog type, and a propeller rotation speed is measured using a counter that measures the rotation speed. May be measured.

  The data processing device 14 is a device that specifies the ship's speed against water using information acquired from each of the water speedometer 11, the ground speedometer 12, and the tachometer 13. The speed of the ship against the water is normally specified by the measurement of the speedometer 11 against the water. However, the anti-watercraft speed measured by the anti-watercraft speedometer 11 may be abnormal. The data processing device 14 specifies a watercraft speed with high validity in a period in which the watercraft speed measured by the watercraft speedometer 11 shows an abnormality. Further, if the watercraft speedometer 11 is not adjusted correctly, the waterspeed measured by the waterspeedometer 11 is biased with respect to the correct waterspeed. The data processing device 14 corrects the bias included in the speed of the watercraft measured by the speedometer 11 of the watercraft.

  FIG. 2 is a diagram illustrating a hardware configuration of the data processing device 14. The hardware of the data processing apparatus 14 is a general computer, and includes a control unit 101, a communication unit 102, a storage unit 103, an operation unit 104, and a display unit 105.

  The control unit 101 includes, for example, a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM). The CPU controls each unit of the data processing device 14 by executing a program stored in the ROM or the storage unit 103. Various programs executed by the CPU and various data are stored in the ROM in advance. The RAM is used as a work area when the CPU executes the program.

  The communication unit 102 is a communication interface connected to a communication line. The communication unit 102 performs data communication via a communication line. The storage unit 103 includes, for example, a hard disk. The storage unit 103 stores various programs executed by the CPU and various data. The operation unit 104 includes a keyboard and a mouse, for example. The operation unit 104 outputs a signal corresponding to a user operation to the control unit 101. The display unit 105 includes, for example, a liquid crystal display. The display unit 105 displays various information.

  FIG. 3 is a diagram illustrating a functional configuration of the data processing device 14. The data processing device 14 includes an acquisition unit 141, a determination unit 143, a correction unit 142, a specifying unit 144, and an output unit 145 as functional components. The acquisition unit 141, the determination unit 143, the correction unit 142, the specification unit 144, and the output unit 145 are realized by the control unit 101 executing processing according to the program according to the present embodiment.

  The acquisition unit 141 acquires the water speed of the ship measured by the water speedometer 11 from the water speedometer 11. Hereinafter, in order to distinguish the anti-water vessel speed measured by the anti-water vessel speed meter 11 from an alternative anti-water vessel speed described later, it is referred to as “measured anti-water vessel speed”. In addition, the acquisition unit 141 acquires the ground speed of the ship measured by the ground speedometer 12 from the ground speedometer 12. Further, the acquisition unit 141 acquires the rotation speed of the propeller measured by the tachometer 13 from the tachometer 13.

  Note that each of the water speedometer 11, the ground speedometer 12, and the tachometer 13 measures the physical quantity to be measured, and then transmits the measured physical quantity to the data processing device 14 immediately. Therefore, the physical quantity acquired from each of the anti-ship speedometer 11, the anti-ship speedometer 12, and the tachometer 13 by the acquisition unit 141 is specified by, for example, a time measuring unit (not shown in FIG. 3) provided in the data processing device 14. It is possible to specify in which period the physical quantity is measured by the current time. Therefore, the determination unit 143, the correction unit 142, and the specification unit 144 can perform temporal association of various types of information acquired by the acquisition unit 141.

  The correction unit 142 includes the measured anti-water vessel speed acquired from the anti-water vessel speed meter 11 via the acquisition unit 141 and the anti-ship vessel speed acquired from the anti-surface vessel speed meter 12 via the acquisition unit 141 within the same period. The measured measurement speed with respect to water and the speed with respect to the ground are associated with each other and stored for a long period of time. That is, the correction unit 142 stores a large number of combinations of the measured ship speed versus the ground ship speed corresponding in time. The correction unit 142 corrects the measured anti-water vessel speed newly delivered from the acquisition unit 141 by using the stored information, and generates the corrected anti-water vessel speed. The process in which the correction unit 142 generates the corrected watercraft speed will be described later.

  The determination unit 143 indicates the degree of deviation between the change in the rotation speed of the propeller measured by the tachometer 13 during a certain period and the change in the speed of the watercraft measured by the watercraft speedometer 11 during the same period. Based on the index value, it is determined whether or not the measured ship speed measured during the period is abnormal. Hereinafter, the period in which the determination unit 143 determines that the measured water speed is abnormal is referred to as an “abnormal measurement period”, and the period in which the determination unit 143 determines that the measurement water speed is not abnormal is the “normal measurement period”. Call it. The process in which the determination unit 143 determines whether or not there is an abnormality in the measured ship speed will be described later.

  When the abnormal measurement period occurs, the specifying unit 144 detects the number of propeller rotations measured by the tachometer 13 during the abnormal measurement period and the normal measurement period within a predetermined time length preceding the abnormal measurement period. The rotation speed of the propeller measured by the tachometer 13 and the anti-watercraft speed measured by the anti-watercraft speedometer 11 and corrected by the correction unit 142 within the normal measurement period, that is, the corrected anti-watercraft speed, are used. The ship speed against water during the abnormal measurement period is specified. Hereinafter, the anti-watercraft speed specified by the specifying unit 144 is referred to as “alternative anti-watercraft speed”. The process in which the specifying unit 144 specifies the alternative anti-watercraft speed will be described later.

  The output unit 145 includes a correction unit (for example, a storage unit) (not shown in FIG. 3) included in the data processing device 14, and a corrected anti-vessel speed for the normal measurement period and an alternative anti-vessel speed for the abnormal measurement period. The data is output to a device different from the data processing device 14 (for example, an external storage device, a display device, a printing device, a server device, etc.).

2. Operation 2.1. Generation of Correction Vessel Speed Below, processing performed by the correction unit 142 to generate correction Vessel speed will be described. As described above, the correction unit 142 determines the measured anti-water vessel speed acquired from the anti-water vessel speedometer 11 via the acquisition unit 141 over the past long term and the anti-ship vessel speed acquired from the anti-surface vessel speed meter 12. It is stored in association with time. FIG. 4 shows a number of combinations of the measured ship speed and the ground ship speed stored in the correction unit 142 of the data processing apparatus 14 mounted on the ship A. It is an example of the graph plotted on the coordinate system which makes speed a vertical axis | shaft. Further, FIG. 5 shows a combination of a number of measured ship speeds and ground ship speeds stored in the correction unit 142 of the data processing apparatus 14 mounted on the ship B different from the ship A. It is an example of the graph plotted on the coordinate system which makes a horizontal axis | shaft and measurement versus water ship speed a vertical axis | shaft.

  The ship speed is not necessarily the same as the ship speed because it is affected by the tidal current that the ship encounters during navigation. However, since the tide direction with respect to the navigation direction changes variously, a sample of a combination of the ground ship speed v [knot] and the water ship speed r [knot] corresponding to each other with respect to a certain ship's navigation is specified. If the samples are randomly obtained without biasing the influence of ocean currents or seasonal winds, and if the number of samples is sufficiently large, the relationship between v and r is r = v (the origin is A straight line with a slope of 1).

However, there is a measurement error between the watercraft speed measured by the watercraft speedometer and the groundcraft speed measured by the ground speedometer. And the bias (specific property that does not represent the population intruded into the sampling data) due to the measured value of the ground speed measured by the ground speedometer (for example, using a satellite positioning system) that is widely spread now Is usually small enough to be ignored. Accordingly, when the relationship between the ground ship speed v measured by the ground speedometer 12 and the measured water speed s measured by the water speedometer 11 is s = f (v), for example, f (v direction and magnitude of deviation from v _{1 1)} shows the bias direction and magnitude of the accompanying measuring ship's speed relative to the water s at v = v _1.

  In the following description, the bias with the measured water speed s measured by the water speed meter 11 is 0 when s = 0, and the measured speed with water increases as the measured speed s increases. It is assumed that it increases in proportion to s. In this case, s = f (v) is approximated by an expression represented by s = av (where a is a coefficient of a first-order term).

  The straight line L1 shown in FIG. 4 is a straight line passing through the origin that approximates the data plotted in FIG. 4, and is represented by s = 0.997902v. Also, the straight line L2 shown in FIG. 5 is a straight line passing through the origin that approximates the data plotted in FIG. 5, and is represented by s = 1.008660v. The correction unit 142 calculates these approximate expressions according to a known algorithm.

  In this case, it is understood that the anti-watercraft speedometer 11 mounted on the ship A measures a value that is about 0.21% smaller than the actual anti-watercraft speed. Moreover, it turns out that the anti-watercraft speedometer 11 mounted in the ship B measures a value about 0.87% larger than the actual anti-watercraft speed.

The correction unit 142 corrects by multiplying the measured ship speed measured by the ship speedometer 11 by the reciprocal (1 / a) of the coefficient a of the first-order term of the approximate expression specified as described above. Calculate ship speed against water. That is, the correction unit 142 calculates the corrected water speed σ according to the following equation 1, where σ is the corrected water speed.

2.2. Output of Water Vessel Speed Subsequently, processing performed by the determination unit 143, the specifying unit 144, and the output unit 145 for outputting the water vessel speed (corrected water vessel speed or alternative water vessel speed) will be described. . For the sake of explanation, the measurement speed measured by the anti-watercraft speedometer 11 within the period T _k (where k is an arbitrary integer) is measured by s _k [knot], and measured by the tachometer 13 within the period T _k . is _r k [rpm] of the propeller speed was, the measured ship's speed relative to the water _{s k} the correction unit 142 and then σ _k [knot] correction ship's speed relative to the water obtained by the correction. The period T _{k + 1} is a period immediately following the period T _k . Note that the period T _k , the period T _{k + 1} , the period T _{k + 2} ,... Have the same time length, for example, but the time lengths of these periods may be different from each other. When a plurality of measuring ship's speed relative to the water in the period T _k is measured, the measuring ship's speed relative to the water s _k representative value of the plurality of measurement ship's speed relative to the water (e.g., average value, the most recent value, etc.) It is.

FIG. 6 is a diagram showing a flow of processing performed by the data processing device 14 for outputting the ship speed. The processing according to the flow shown in FIG. 6 is performed for each of the period T _k , the period T _{k + 1} , the period T _{k + 2} ,.

  First, the determination unit 143 determines whether or not the measured anti-watercraft speed newly acquired from the anti-watercraft speedometer 11 is abnormal (step S1). The determination unit 143 is based on the index value indicating the degree of deviation between the change in the propeller rotation speed acquired from the tachometer 13 and the change in the measurement speed versus the water speed acquired from the speedometer 11. It is determined whether or not the speed is abnormal. Hereinafter, the reason why it is possible to determine whether or not there is an abnormality in the measurement versus water vessel speed based on an index value indicating the degree of deviation between the change in the propeller rotation speed and the change in the measurement vessel speed.

  In general, the main factor that changes the speed of the watercraft is the propeller speed. However, part of the propulsive force generated by the propeller is lost without being used to propel the ship. The loss rate of this propulsive force varies depending on the attitude of the ship, drafts, weather conditions, etc. Therefore, in addition to the rotation speed of the propeller, the attitude of the ship, drafts, weather conditions and the like are factors that change the speed of the watercraft.

  However, all of the factors that change the speed of the watercraft except for the propeller speed are generally slower than the propeller speed. Therefore, the loss rate of the propulsive force generated by the propeller can be regarded as constant within a short time. Therefore, within a short time, the ratio between the propeller rotation speed and the water vessel speed is substantially constant.

  Therefore, when the change in the propeller rotation speed measured during a certain period and the change in the measured ship speed are significantly different, the measured ship speed measured during the certain period is likely to be abnormal.

Based on the above reason, in the process of step S1, the determination unit 143 determines that the measured ship speed s _j measured in the period T _j (an example of the first period) is, for example, when the following Expression 2 is satisfied. When it is normal and Expression 2 is not satisfied, it is determined that the measured ship speed s _j is abnormal. However, i and j represent natural numbers (i <j) corresponding to different periods, and the period T _i (an example of the second period) is the last normal measurement period before the period T _j . Further, (1-e) is a lower limit threshold value for detecting an abnormality in the measurement versus water vessel speed, and (1 + e) is an upper limit threshold value for detecting an abnormality in the measurement vs. water vessel speed. (E is a positive number less than 1)

In this case, the ratio indicated by R _j in the above equation 2 (hereinafter referred to as “ratio R”) is an index value indicating the degree of deviation between the change in the propeller rotational speed and the change in the measurement speed versus the water speed in the period T _j . It is. FIG. 7 is a graph showing an example of the time series change of the ratio R. Within the period illustrated in FIG. 7, the ratio R regarding the period T _{k + 1} and the period T _{k + 2} is out of the range from the lower limit to the upper limit of the threshold (hereinafter referred to as “normal range”), and the ratio R regarding the other periods. Is within the normal range. In this case, the period _{T k +} measuring ship's speed relative to the water was measured in _{1 s k + 1,} the period _{T k +} measuring ship's speed relative to the water was measured _{2 s k + 2,} the period _{T k + 3} Measurement ship's speed relative to the water was measured in _{s k + 3} is abnormal There is a high probability that the measured speed versus water speed measured during other periods is likely to be normal.

In the case illustrated in FIG. 7, for example, in step S _< b> 1 regarding the period T _k , the last normal measurement period is the period T _k−1 . Therefore, the determination unit 143 performs determination according to Expression 2 with i = k−1 and j = k. In step S1 regarding the period T _{k + 1} , the last normal measurement period is the period T _k . Therefore, the determination unit 143 performs determination according to Expression 2 with i = k and j = k + 1. In step S1 for the period T _{k + 2} , the last normal measurement period is the period T _k . Therefore, the determination unit 143 performs determination according to Expression 2 with i = k and j = k + 2. Thus, in the determination of step S1 regarding the period following the abnormal measurement period, it is measured in the last normal measurement period, not in the propeller rotation speed and the measured speed against water speed measured in the immediately preceding period (abnormal measurement period). The propeller speed and the measured ship speed are used.

When the determination unit 143 determines that the measured ship speed is abnormal (step S1: “Yes”), the specifying unit 144 newly sets the abnormality measurement period and the determination unit 143 according to the following Expression 3, for example. identifying the ship's speed relative to the water in the determined time period T _j Alternatively ship's speed relative to the water S _j (step S2). Where Q _i is the propeller slip in the last normal measurement period T _i (no unit for the ratio), and P [m] is the propeller pitch (theoretical value of the distance traveled by the propeller per revolution, the ship or the same type of ship) Group-specific constant). The multiplier “1852” is a constant for converting the unit of the ship speed [knot] to [m / hour], and the multiplier “60” is the unit of the propeller revolution [rpm]. Constant for converting to a number. Also, σ _i [knot] is the corrected anti-watercraft speed generated by the correction unit 142 for the last normal measurement period T _i , and σ _j [knot] is the correction pair generated by the correction unit 142 for the abnormal measurement period T _j . It is a watercraft speed.

Note that Equation 3 above can be rewritten as Equation 4 below.

The specifying unit 144 delivers the alternative anti-watercraft speed _Sj specified in step S _< b> 2 to the output unit 145. The output unit 145 outputs the alternative anti-watercraft speed S _j delivered from the specifying unit 144 to, for example, a storage device, a display device, a printing device, or the like (step S3).

In step S <b> 1, when the determination unit 143 determines that the measured ship speed is normal (step S <b> 1: “No”), the correction unit 142 newly determines the normal measurement period by the determination unit 143. The corrected ship speed σ _j generated for T _{j is} delivered to the output unit 145. The output unit 145 outputs the corrected water speed σ _j delivered from the correction unit 142 to, for example, a storage device, a display device, a printing device, or the like (step S4).

  According to the anti-watercraft speed specifying system 1 described above, when the anti-watercraft speed measured by the anti-watercraft speedometer 11 indicates an abnormality, the data processing device 14 causes the anti-watercraft speed to be high. It is specified on the basis of the propeller slip during the normal measurement period, and is output instead of the measured speed of water vessel indicating an abnormality. Therefore, a device or a user who uses the speed of the watercraft output from the data processing device 14 is always highly valid even when the waterspeedometer 11 suddenly outputs an abnormal measurement value. Ship speed against water can be obtained.

  Further, according to the anti-watercraft speed specifying system 1 described above, the adjustment of the anti-watercraft speedometer 11 is incomplete, and when the anti-watercraft speedometer 11 is biased, The ship speed against water with the bias removed is output. Therefore, a device or a user who uses the anti-watercraft speed output from the data processing device 14 can obtain a highly accurate anti-watercraft speed even if the anti-watercraft speedometer 11 is not fully adjusted. .

3. Modifications The above-described anti-watercraft speed identification system 1 is an embodiment of the present invention, and may be variously modified within the scope of the technical idea of the present invention. Examples of these modifications are shown below. Two or more of the following modifications may be combined.

(1) In embodiment mentioned above, the specific | specification part 144 uses the measurement versus watercraft speed and propeller rotation speed of the last period among the past normal measurement periods, when specifying the alternative versus watercraft speed regarding an abnormal measurement period. Is adopted. The measurement anti-water vessel speed and the propeller rotational speed used when the specifying unit 144 specifies the alternative anti-water vessel speed relating to the abnormal measurement period are sufficiently close to the abnormal measurement period and the propeller slip of the target for specifying the alternative anti-water vessel speed. If it is a normal measurement period, the measurement versus water speed and propeller rotation speed of any normal measurement period may be used.

  For example, the measurement versus water speed and the propeller rotational speed in the normal measurement period arbitrarily selected from the normal measurement periods within the past predetermined time length among the past normal measurement periods may be used. Moreover, even if typical values (average value, median value, etc.) of the water speed and propeller rotation speed for each measurement in the normal measurement period within the past predetermined time length of the past normal measurement period are used. Good.

  In addition, when the real-time property of the speed of the water vessel output from the data processing device 14 is not required, the normal measurement closest to the abnormal measurement period in the normal measurement period within the predetermined time length following the abnormal measurement period. Period measurements versus watercraft speed and propeller speed may be used. Moreover, the measurement versus water speed and the propeller rotation speed in the normal measurement period arbitrarily selected among the normal measurement periods within the predetermined time length following the abnormal measurement period may be used. In addition, representative values (average value, median value, etc.) of the measured ship speed and the propeller rotation speed in each normal measurement period within a predetermined time length following the abnormal measurement period may be used.

  In addition, regardless of whether it is close in time to the abnormal measurement period of the target for specifying the alternative ship speed, the ship's attitude, draft, weather conditions (including wind direction, tide direction, wave direction, etc. to the course), etc. The measurement vs. watercraft speed and the propeller rotation speed in the normal measurement period that are the same or similar may be used to specify the alternative vs. watercraft speed. In this case, the data processing device 14 determines the attitude, draft, course, wind direction (wind direction) and speed (wind speed) encountered, direction (tide direction) and speed (tide speed) encountered, Information on weather or sea conditions such as the direction (wave direction) and height (wave height) of the generated waves from various measurement devices mounted on the ship, land server devices that can be accessed via communication satellites, etc. Acquire and store the information acquired in the past. And the specific | specification part 144 selects the normal measurement period in which the attitude | position of a ship, draft, a weather sea state, etc. are the same or similar in the abnormal measurement period of the object which specifies alternative anti-watercraft speed, and measurement of the selected normal measurement period Vessel speed and propeller speed are used to identify alternative Vessel speed. Note that the specifying unit 144 determines whether or not the postures, drafts, weather conditions, and the like of the ship in different periods are the same or similar, for example, the difference or ratio of the same parameter values in different periods is within a predetermined range. It is based on whether or not.

(2) In the embodiment described above, the correction unit 142 uses the ground speedometer 12 to measure a correction coefficient (1 / a) for correcting the measurement speed against water speed and calculating the corrected speed vs water speed in the past. It calculates by calculating | requiring the approximate expression which shows the relationship between the measured anti-ship speed and the anti-water ship speed measured by the anti-water speedometer 11 in the past. The correction unit 142 estimates the ship speed against water reflecting the influence of the tidal current that the ship has encountered on the ground ship speed measured by the ground ship speedometer 12 in the past. A correction coefficient (1 / a) for calculating the corrected anti-water vessel speed by obtaining an approximate expression indicating the relationship between the anti-water vessel speed (hereinafter referred to as “estimated anti-water vessel speed”) and the measured anti-water vessel speed. ) May be adopted.

  In this case, the data processing device 14 acquires the tide direction and tide speed (information indicating weather or sea conditions) encountered by the ship from, for example, a land server device accessible via a communication satellite. The correction unit 142 identifies the estimated watercraft speed by dividing the vector indicated by the tide and tide obtained from the server device from the groundcraft speed obtained from the groundcraft speedometer 12, and determines the watercraft speed. The data is stored in association with the measured ship speed obtained from the speedometer 11. The relationship between the estimated watercraft speed and the measured watercraft speed stored in the correction unit 142 is originally approximated to a straight line with a slope of 1 passing through the origin. That is, the sample of the combination of the estimated anti-watercraft speed and the measured anti-watercraft speed stored in the correction unit 142 is a randomly obtained sample that does not include biased effects of specific ocean currents, seasonal winds, etc. If the number of the samples is sufficiently large, the approximate curve of the scatter diagram in which the samples are plotted is a straight line having a slope of 1 through the origin. Therefore, the correction unit 142 obtains a straight line that passes through the origin that approximates the relationship between the estimated water speed and the measured water speed, and calculates the coefficient of the first-order term representing the straight line as the bias of the measured water speed. Specified as a value indicating. The correction unit 142 corrects the measured ship speed based on the coefficient of the first-order term of the identified approximate expression, and generates the corrected ship speed.

  In the case of the above-described embodiment, the ground speed is used as it is for specifying the correction coefficient. Therefore, when the direction of the tidal current is biased in a certain direction in the navigation route, in order to remove the bias, It is necessary to use data collected over a long period of time, such as using data. According to this modification, since the ship speed against water (estimated ship speed) in consideration of the influence of tide direction and tide speed is used to specify the correction coefficient, compared to the case where the ground ship speed is used as it is, It is easy to collect the required data.

(3) In the above-described embodiment or modification (2), the bias associated with the measured water speed s measured by the water speed meter 11 is 0 when s = 0, and the measured speed versus water speed It is assumed that as s increases, it increases in proportion to the measured speed vs. watercraft speed s. The characteristics of the bias associated with the measured water speed s vary depending on the method of the water speed meter 11 and the adjustment method. Therefore, the relationship between the ground ship speed v and the measured ship speed s is not limited to the relationship represented by s = av.

  For example, due to the influence of noise or the like, there may be a case where a steady bias component that is irrelevant to the magnitude of the measured ship speed s is accompanied in all speed regions. In this case, s = f (v), which is an expression showing the relationship between the ground ship speed v and the measured ship speed s, is as follows: s = av + b (where a is a coefficient of a primary term and b is a constant) In addition, s = f (v) is an expression including a constant b indicating a steady bias component.

  For example, when the increase rate of the bias increases as the measured speed vs. water speed s increases, s = f (v) is a polynomial or the like.

Therefore, a configuration in which the correction unit 142 calculates an approximate expression s = f (v) other than s = av may be employed according to the method of the anti-ship speedometer 11 or the like. In this case, the correction unit 142 calculates the corrected anti-water vessel speed σ according to the following equation 5 where σ is the corrected anti-water vessel speed. However, f ⁻¹ is an inverse function of f.

  Furthermore, the relationship between the ground ship speed v and the measured ship speed s specified by the correction unit 142 may not be expressed by a mathematical expression. For example, the correction unit 142 specifies the ratio between the representative value (average value or the like) of the ground ship speed v and the representative value (average value or the like) of the measured ship speed s for various ship speeds, and the specified ratio May be held in the form of a table. In this case, the correction unit 142 calculates a corrected water speed σ corresponding to the given measured water speed s based on the ratio held in the table.

(4) In the above-described embodiment, the specifying unit 144 specifies the alternative anti-watercraft speed only for the abnormal measurement period. Instead of this, a configuration may be adopted in which the specifying unit 144 specifies the alternative anti-watercraft speed regardless of whether or not it is an abnormal measurement period.

  In this case, the determination by the determination unit 143 may not be performed. And the output part 145 is good also as a structure which outputs the correction | amendment anti-watercraft speed produced | generated by the correction | amendment part 142, and the alternative anti-watercraft speed specified by the specific | specification part 144 regarding each of all the periods, for example. For example, when there is a large difference between the corrected anti-watercraft speed obtained from the output unit 145 and the alternative anti-watercraft speed, the device or user using the anti-watercraft speed output from the output unit 145 sets the alternative anti-watercraft speed. Select and use.

  In addition, the determination unit 143 determines a period in which a difference between the corrected anti-watercraft speed generated by the correction unit 142 and the alternative anti-watercraft speed generated by the specifying unit 144 is small as a normal measurement period, It is good also as a structure which determines a period with a big difference | error as an abnormal measurement period.

(5) A configuration in which the data processing device 14 does not include the correction unit 142 provided in the above-described embodiment may be employed. In this case, instead of the corrected watercraft speed generated by the correction unit 142, the measured watercraft speed acquired by the acquisition unit 141 from the watercraft speedometer 11 is used. If the watercraft speedometer 11 is adjusted correctly, the data processing device 14 can always output a watercraft speed with high validity without the correction unit 142.

(6) In the above-described embodiment, the determination unit 143 uses the measured water speed obtained from the water speedometer 11 for determination. Instead, a configuration in which the determination unit 143 uses the corrected anti-watercraft speed generated by the correction unit 142 for determination may be employed.

(7) In the above-described embodiment, the determination unit 143 determines the ratio R _j shown in Equation 2 in the period when determining whether the measured ship speed s _j measured in the period T _j shows an abnormal value. used as an index value indicating the degree of divergence of change of T _j in the measured measured in propeller speed of change and duration T _j was measured ship's speed relative to the water s _j. The index value used by the determination unit 143 in determining whether or not the measured ship speed s _j measured during the period T _j indicates an abnormal value is not limited to the ratio R _j . For example, the determination unit 143, in the process of step S1, instead of the equation 2 described above, if Equation 6 below is satisfied, the period T _j measured ship's speed relative to the water s _j which is measured is normal, the formula If 6 is not satisfied, a configuration may be adopted in which it is determined that the measured ship speed s _j is abnormal.

In this case, R _j shown in the above equation 6 is an index value indicating the degree of deviation between the change in the propeller rotation speed and the change in the measurement versus water speed in the period T _j .

The determination unit 143, in the process of step S1, instead of the equation 2 described above, if the expression 7 or Formula 8 below is satisfied, measured ship's speed relative to the water s _j which is measured in the period T _j is normal There may be adopted a configuration in which when the formula 7 or the formula 8 is not satisfied, it is determined that the measured ship speed s _j is abnormal. However, t _L is the lower threshold for the detection of measurement ship's speed relative to the water anomaly, t _U is the upper limit threshold value for the detection of measurement ship's speed relative to the water anomaly.

In this case, D _j shown in the above equation 7 or 8 is an index value indicating the degree of deviation between the change in the propeller rotational speed and the change in the measurement speed versus the water speed in the period T _j .

(8) In the embodiment described above, the data processing device 14 is realized by a general computer executing processing according to a program. Alternatively, the data processing device 14 may be realized as a dedicated device by a combination of, for example, integrated circuits.

(9) A program used for realizing the data processing apparatus 14 is downloaded to a computer via a network such as the Internet. The program continuously records data in a computer-readable state such as a magnetic recording medium (magnetic tape, magnetic disk, etc.), an optical recording medium (optical disk, etc.), a magneto-optical recording medium, and a semiconductor memory. You may provide in the state recorded on the recording medium.

(10) In the above-described embodiment, all the components of the anti-watercraft speed identification system 1 are mounted on the ship. Instead of this, a part of the components included in the anti-watercraft speed specifying system may be arranged outside the ship. FIG. 8 is a diagram illustrating an overall configuration of the anti-watercraft speed identification system 2 according to a modification in which a part of the configuration unit is disposed outside the ship. In FIG. 8, the same code | symbol is attached | subjected to the same part as the structural part with which the anti-watercraft speed specific system 1 concerning embodiment mentioned above among the structural parts with which the anti-watercraft speed specific system 2 is provided.

  The anti-watercraft speed specifying system 2 includes a server device 25 outside the ship (on land in the example of FIG. 8). The server device 25 performs processing performed by the data processing device 14 of the anti-watercraft speed identification system 1. The anti-watercraft speed specifying system 2 includes a data processing device 24 instead of the data processing device 14 of the anti-watercraft speed specifying system 1. The data processing device 24 is mounted on a ship and receives physical quantities measured by the anti-ship speedometer 11, the anti-ship speedometer 12, and the tachometer 13, and receives the received physical quantities and measurement time (for example, current time). The associated data is transmitted to the server device 25 via the communication satellite 9.

  The hardware configuration of the data processing device 24 is the same as the hardware configuration of the data processing device 14 (FIG. 2). However, the communication unit 102 of the data processing device 24 can communicate with the server device 25 via the communication satellite 9 in addition to the communication with the water speedometer 11, the ground speedometer 12, and the tachometer 13. is there.

  The hardware configuration of the server device 25 is the same as that of a general server device computer, for example. That is, the computer used to implement the server device 25 includes a storage unit that stores various data, a control unit that performs data processing according to a program stored in the storage unit, and a communication unit that performs data communication with an external device. Prepare. Note that the communication unit included in the computer used to implement the server device 25 can perform data communication with the data processing device 24 via the communication satellite 9.

  FIG. 9 is a diagram showing a functional configuration of the data processing device 24. The data processing device 24 includes an acquisition unit 241 that acquires data indicating physical quantities measured from each of the anti-ship speedometer 11, the anti-ship speedometer 12, and the tachometer 13, and the data (measurement time) acquired by the acquisition unit 241 The output unit 242 is transmitted to the server device 25. In addition, the data processing device 24 receives, for example, data indicating the corrected anti-watercraft speed and the alternative anti-watercraft speed transmitted from the server device 25 as a response to the data transmitted by the output unit 242; An output unit 244 that outputs data received by the acquisition unit 243 to a storage device, a display device, a printing device, or the like is provided.

  FIG. 10 is a diagram showing a functional configuration of the server device 25. The functional configuration of the server device 25 is substantially the same as the functional configuration of the data processing device 14 of the anti-watercraft speed identification system 1. That is, the server device 25 includes an acquisition unit 251 to an output unit 255 as components corresponding to each of the acquisition unit 141 to the output unit 145 included in the data processing device 14. The acquisition unit 251 receives data transmitted from the data processing device 24. The correction unit 252, the determination unit 253, and the specification unit 254 each perform processing performed by the correction unit 142, the determination unit 143, and the specification unit 144 of the data processing device 14 using the data received by the acquisition unit 251.

  For the normal measurement period, the output unit 255 includes data indicating the corrected anti-watercraft speed generated by the correction unit 142, and regarding the abnormal measurement period, data indicating the alternative anti-watercraft speed specified by the specifying unit 144, The data is transmitted to the processing device 24. When the computer used to implement the server device 25 has a built-in display device, or when an output device such as a display device or a printing device is connected to the computer, the output unit 255 may provide a corrected water speed or alternative You may output the data which show the ship speed to water to these output devices.

  The server device 25 receives data from each of the data processing devices 24 mounted on a plurality of ships, and generates and outputs data indicating the corrected water speed and the alternative water speed for each of these ships. A configuration may be employed.

  DESCRIPTION OF SYMBOLS 1 ... Watercraft speed specific system, 2 ... Watercraft speed specific system, 9 ... Communication satellite, 11 ... Watercraft speedometer, 12 ... Ground speedometer, 13 ... Tachometer, 14 ... Data processor, 24 Data processing device 25 ... Server device 101 ... Control unit 102 ... Communication unit 103 ... Storage unit 104 ... Operation unit 105 ... Display unit 141 ... Acquisition unit 142 ... Correction unit 143 ... Determination unit 144: identification unit, 145 ... output unit, 241 ... acquisition unit, 242 ... output unit, 243 ... acquisition unit, 244 ... output unit, 251 ... acquisition unit, 252 ... correction unit, 253 ... determination unit, 254 ... identification unit, 255: Output unit

Claims (17)

The propeller rotation speed of the ship measured within the first period, the speed of the ship against water measured within the second period different from the first period, and the second period are measured. Using the propeller rotational speed of the ship, the ship's speed against water in the first period when the propeller slips in the first period and the second period are substantially the same. A device with a specific part to identify. Based on an index value indicating the degree of deviation between the change in the propeller rotation speed of the ship measured during the first period and the change in the speed of the ship against water measured during the first period. A determination unit that determines whether or not the speed of the ship against water measured within the first period is abnormal;
When the determination unit determines that the ship's speed against water measured within the first period is not abnormal, outputs the ship's speed against water measured within the first period; When the determination unit determines that the water speed of the ship measured in the first period is abnormal, the anti-ship ship of the ship in the first period specified by the specifying unit The apparatus of Claim 1 provided with the output part which outputs a speed. In the predetermined time length period preceding the first period, or in the predetermined time length period subsequent to the first period, the specifying unit determines whether the determination unit has measured the ship. 3. The apparatus according to claim 2, wherein a period when it is determined that the ship's speed against water is not abnormal is set as the second period, and the ship's speed against water within the first period is specified. The specifying unit is a period in which the ship encounters a weather or sea condition that is the same as or similar to the weather or sea condition encountered by the ship within the first period, and the determination unit is configured to measure the measured ship 4. The apparatus according to claim 2, wherein the water speed of the ship in the first period is specified with the period when it is determined that the water speed of the ship is not abnormal as the second period. 5. Using the ship's ground speed measured within the period and the ship's water speed measured during the period for each of a plurality of periods, the measured ground speed and the measured A correction unit is provided that specifies a relationship with the speed of the watercraft, and corrects the measured value of the speed of the watercraft for the watercraft so that the identified relationship is a relationship indicated by a straight line with an inclination passing through the origin. Apparatus according to any one of claims 1 to 4. With respect to each of a plurality of periods, the ship's speed relative to the ground during the period estimated based on the ship's ground speed measured within the period and the weather or sea condition encountered by the ship during the period. The relationship between the estimated anti-watercraft speed and the measured anti-watercraft speed is identified and identified using the estimated anti-watercraft speed and the anti-watercraft speed of the ship measured during the period. The correction | amendment part which correct | amends the measured value of the water-vessel speed of the said ship so that the relationship which became the relationship shown by the straight line with the inclination which passes along an origin as 1 may be provided. Equipment. Using the ship's ground speed measured during the period and the ship's water speed measured during the period for each of a plurality of periods, the measured ground speed and the measured pair speed An apparatus comprising: a correction unit that specifies a relationship with water speed, and corrects the measured value of water speed of the vessel so that the specified relationship becomes a relationship indicated by a straight line with an inclination passing through the origin. . For each of a plurality of periods, the ship's speed relative to the ground during the period estimated based on the ship's ground speed measured during the period and the weather or sea condition encountered by the ship during the period. The relationship between the estimated anti-watercraft speed and the measured anti-watercraft speed was identified and specified using a certain anti-watercraft speed and the anti-watercraft speed of the ship measured within the period. An apparatus comprising: a correction unit that corrects the measured value of the ship's speed against water so that the relationship is a relationship indicated by a straight line with an inclination passing through the origin . Measuring the propeller rotation speed of the ship within the first period;
Measuring a propeller rotation speed of the ship within a second period different from the first period;
Measuring the speed of the vessel against water within the second period;
A pair of the propeller rotation speed of the ship measured within the first period, a propeller rotation speed of the ship measured within the second period, and a pair of the ship measured within the second period. Identifying a watercraft speed of the ship within the first period when the propeller slip of the first period and the second period is substantially the same using the watercraft speed; A method comprising: For each of the multiple periods,
Measuring the ship's ground speed during the period;
Measuring the speed of the ship against water during the period;
Identifying the relationship between the measured ground speed and the measured water speed;
Correcting the measured value of the vessel's speed against water so that the specified relationship becomes a relationship indicated by a straight line with an inclination passing through the origin . For each of the multiple periods,
Measuring the ship's ground speed during the period;
Estimating the ship's speed against water in the period based on the measured ship speed and the weather or sea condition encountered by the ship in the period;
Measuring the speed of the ship against water during the period;
Identifying a relationship between the estimated anti-watercraft speed and the measured anti-watercraft speed;
Correcting the measured value of the vessel's speed against water so that the specified relationship becomes a relationship indicated by a straight line with an inclination passing through the origin . On the computer,
The propeller rotation speed of the ship measured within the first period, the speed of the ship against water measured within the second period different from the first period, and the second period are measured. Using the propeller rotational speed of the ship, the ship's speed against water in the first period when the propeller slips in the first period and the second period are substantially the same. A program for executing the specified process. On the computer,
Using the ship's ground speed measured during the period and the ship's water speed measured during the period for each of a plurality of periods, the measured ground speed and the measured pair speed Processing to identify the relationship with the watercraft speed,
A program for executing a process of correcting the measured value of the ship's speed against water so that the specified relation becomes a relation indicated by a straight line with an inclination passing through the origin . On the computer,
For each of a plurality of periods, the ship's speed relative to the ground during the period estimated based on the ship's ground speed measured during the period and the weather or sea condition encountered by the ship during the period. A process for identifying a relationship between the estimated anti-watercraft speed and the measured anti-watercraft speed using a certain estimated anti-watercraft speed and the anti-watercraft speed of the ship measured within the period;
A program for executing a process of correcting the measured value of the ship's speed against water so that the specified relation becomes a relation indicated by a straight line with an inclination passing through the origin . On the computer,
The propeller rotation speed of the ship measured within the first period, the speed of the ship against water measured within the second period different from the first period, and the second period are measured. Using the propeller rotational speed of the ship, the ship's speed against water in the first period when the propeller slips in the first period and the second period are substantially the same. A computer-readable recording medium that continuously records a program for executing a specified process. On the computer,
Using the ship's ground speed measured during the period and the ship's water speed measured during the period for each of a plurality of periods, the measured ground speed and the measured pair speed Processing to identify the relationship with the watercraft speed,
A program for continuously executing the process of correcting the measured value of the ship's speed relative to water so that the specified relation becomes a relation indicated by a straight line with an inclination through the origin of 1 is recorded. Computer-readable recording medium. On the computer,
For each of a plurality of periods, the ship's speed relative to the ground during the period estimated based on the ship's ground speed measured during the period and the weather or sea condition encountered by the ship during the period. A process for identifying a relationship between the estimated anti-watercraft speed and the measured anti-watercraft speed using a certain estimated anti-watercraft speed and the anti-watercraft speed of the ship measured within the period;
A program for continuously executing the process of correcting the measured value of the ship's speed relative to water so that the specified relation becomes a relation indicated by a straight line with an inclination through the origin of 1 is recorded. Computer-readable recording medium.

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