Ship speed indicator and ship speed measurement method

Abstract

To find an accurate vessel speed.SOLUTION: A value of a momentary speed the acceleration of which is within a predetermined range among values of measured momentary speeds of a vessel is stored in a buffer for a predetermined period, and values of momentary speeds stored in the buffer are used to measure a vehicle speed value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a boat speed meter and a boat speed measurement method, and to a technique useful for measuring boat speed. [Background technology]

[0002] One known method of measuring ship speed is the acoustic method (also known as the "Doppler method"). Acoustic speed meters emit sound waves from the ship into the water, and calculate the ship's relative speed with respect to the water based on the difference between the frequency of the emitted sound waves and the frequency of the sound waves reflected by floating objects in the water (specifically, plankton, etc.) (i.e., the Doppler frequency corresponding to the relative speed) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 61-099868 Summary of the Invention [Problem to be solved by the invention]

[0004] However, ship speed measured by a speedometer can sometimes indicate an abnormal value. For example, an acoustic speedometer may indicate an abnormal Doppler frequency due to external noise or bubble entrapment. In this case, if the abnormal Doppler frequency is used to calculate ship speed, an incorrect ship speed value will be output and displayed, which is a problem. Ship speed meters using methods other than acoustic can also indicate an abnormal value due to noise being superimposed on the signals used for measurement, which can lead to the output and display of an incorrect ship speed value.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a boat speed meter and a boat speed measuring method that are capable of determining an accurate boat speed. [Means for solving the problem]

[0006] In order to solve the above problem, the boat speed meter according to the present invention comprises: A ship speed meter that calculates a ship speed value at a predetermined time interval, stores a predetermined number of the ship speed values ​​calculated before a previous process in a second buffer, calculates a reference acceleration at the predetermined time interval using the ship speed values ​​stored in the second buffer, and calculates a reference acceleration between the previous process and the current process. Measured The aforementioned The instantaneous speed of the ship , applicable The acceleration related to the instantaneous velocity is Centered on the reference acceleration Instantaneous speed values ​​within a predetermined range are stored in a buffer for a predetermined period of time, and the instantaneous speed values ​​stored in the buffer are used to calculate the speed. In this process Calculate ship speed death , The acceleration related to the instantaneous speed refers to the acceleration when the boat speed value calculated in the previous processing changes to the instantaneous speed value. It is characterized by:

[0008] The boat speed meter according to the present invention may be configured to calculate the acceleration used as a reference for the predetermined range only when the instantaneous speed value stored in the buffer is updated.

[0009] The boat speed meter according to the present invention may be configured to change the conditions defining the predetermined range when a predetermined condition is satisfied in a situation where the instantaneous speed value stored in the buffer has not been updated.

[0010] In the boat speed meter according to the present invention, the method for measuring the instantaneous speed may be an acoustic method.

[0011] The boat speed measurement method according to the present invention further comprises: A method for calculating a ship speed value at a predetermined time interval, the method comprising: storing a predetermined number of the ship speed values ​​calculated before a previous process in a second buffer; calculating a reference acceleration at the predetermined time interval using the ship speed values ​​stored in the second buffer; and The measured instantaneous speed of the vessel , applicable The acceleration related to the instantaneous velocity is Centered on the reference acceleration Instantaneous speed values ​​within a predetermined range are stored in a buffer for a predetermined period of time, and the instantaneous speed values ​​stored in the buffer are used to calculate the speed. In this process Calculate ship speed death , The acceleration related to the instantaneous speed refers to the acceleration when the boat speed value calculated in the previous processing changes to the instantaneous speed value. It is characterized by:

[0013] The boat speed measuring method according to the present invention may be configured to calculate the acceleration used as a reference for the predetermined range only when the instantaneous speed value stored in the buffer is updated.

[0014] The ship speed measurement method of the present invention may also be configured to change the conditions defining the specified range when a specified condition is met in a situation where the instantaneous speed value stored in the buffer has not been updated.

[0015] In the boat speed measuring method according to the present invention, the instantaneous speed may be measured by an acoustic method. [Effects of the Invention]

[0016] According to the speed meter and the speed measurement method of the present invention, the speed value is calculated using only the instantaneous speed value when the acceleration related to the instantaneous speed is within a predetermined range, so that the instantaneous speed value based on an abnormal Doppler frequency can be excluded when calculating the speed value, and an accurate speed can be obtained. Furthermore, according to the speed meter and the speed measurement method of the present invention, the acceleration is used as the judgment criterion, so the trend of the speed can be used as the judgment criterion, and a more natural speed value can be calculated.

[0017] According to the ship speed meter and ship speed measurement method of the present invention, the acceleration used as the basis for abnormality judgment is calculated based on the ship speed value calculated using a normal (in other words, within the acceptable range) instantaneous speed value, making it possible to determine the accurate ship speed. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a functional block diagram showing a schematic configuration of a boat speed meter according to an embodiment of the present invention; [Figure 2] 2 is a flowchart showing the processing procedure in the boat speed meter of FIG. 1 and also showing an outline of the processing procedure of the boat speed measuring method according to the embodiment of the present invention. [Figure 3] 2 is a diagram illustrating a reference acceleration calculated in the boat speed meter of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described below based on the illustrated embodiments.

[0020] Fig. 1 is a functional block diagram showing a schematic configuration of a boat speed meter 1 according to an embodiment of the present invention. Fig. 2 is a flowchart showing the processing procedure in the boat speed meter 1 and also showing an outline of the processing procedure of a boat speed measuring method according to an embodiment of the present invention.

[0021] The ship speed meter 1 has the configuration and function of an acoustic (also called "Doppler") ship speed meter, and is a mechanism that is installed on a ship to measure and output the ship's speed through the water (i.e., ship speed through the water [kn]), and mainly has a control unit 2, a memory unit 3, a sensor 4, a measurement unit 5, a ship speed calculation unit 6, an interface unit 7, and a display unit 8.

[0022] In the ship speed meter 1 of this embodiment, the abnormal value determination unit 62 stores in the instantaneous ship speed buffer 31 the instantaneous water speed values ​​of the ship measured and calculated by the sensor 4, the measurement unit 5, and the instantaneous ship speed calculation unit 61, of which the acceleration related to the instantaneous water speed is within a predetermined range, and the ship speed value calculation unit 63 calculates the ship speed value V using the instantaneous water speed values ​​for a predetermined period stored in the instantaneous ship speed buffer 31, and when the update determination unit 64 determines that the instantaneous water speed value stored in the instantaneous ship speed buffer 31 has been updated, the reference acceleration calculation unit 65 calculates the reference acceleration ar to be used as the reference for the predetermined range (see Figure 1).

[0023] In addition, the ship speed measurement method of the embodiment stores the instantaneous water speed values ​​of the measured ship, among which the acceleration related to the instantaneous water speed is within a predetermined range, in the instantaneous ship speed buffer 31 for a predetermined period (steps S1 to S4), calculates the ship speed value V using the instantaneous water speed values ​​stored in the instantaneous ship speed buffer 31 (step S5), and if the instantaneous water speed value stored in the instantaneous ship speed buffer 31 has been updated (step S7: Yes), calculates the reference acceleration ar used as the basis for the predetermined range (steps S9, S10) (see Figure 2).

[0024] The control unit 2 has the function of controlling the operation of each part that makes up the speed meter 1, and is configured as a mechanism that has, for example, a central processing unit (CPU: abbreviation for Central Processing Unit) that performs calculations related to measuring the ship's speed through water (ship speed through water).

[0025] The control unit 2 controls the start, content, and end of processing of each part that constitutes the speed meter 1 in accordance with a program (not shown) stored in the memory unit 3, by having the central processing unit execute the program for controlling the operation of the speed meter 1.

[0026] The memory unit 3 has a function of serving as a working area for temporarily storing data and information generated when the central processing unit performs calculations related to the measurement of the water speed of the ship (ship speed through water), and as a memory area for storing and storing various information, programs, and data, and may be, for example, a ROM (short for Read Only Memory), which is a readable memory device, a RAM (Random Access Memory), which is a readable and writable memory device, or the like. It is configured as a mechanism having at least one of the following: a hard disk drive (short for "hard disk drive memory"), and a hard disk.

[0027] The sensor 4 is installed, for example, on or near the bottom of the hull, and has the function of emitting (in other words, emitting or transmitting) pulsed sound waves at a predetermined frequency into the water at regular time intervals, and continuously receiving (in other words, detecting) the reflected waves of the sound waves from when the sound waves are emitted until the next sound wave is emitted. That is, the sensor 4 alternately repeats the emission of pulsed sound waves and the reception of the reflected waves of the sound waves. However, the measurement method of the sensor 4 is not limited to the above method, and for example, it may be configured to transmit a continuous signal and receive a reflected signal of the signal.

[0028] The sensor 4 then outputs at least the frequency of the received reflected wave. The sensor 4 may be configured by, for example, a transducer.

[0029] The fixed time interval at which the sensor 4 emits sound waves is called the "measurement time interval," and its value is denoted as Δt. The measurement time interval Δt [seconds] is not limited to a specific time length, but may be set to any time length within the range of approximately 20 to 80 milliseconds, for example.

[0030] That is, the sensor 4 outputs data on the frequency of the reflected wave (referred to as the "reflected wave frequency") at each measurement time interval Δt. Note that the sensor 4 may also output other information / data as necessary.

[0031] The measurement unit 5 has a function of controlling the operation of the sensor 4 to perform measurements using the sensor 4, and acquiring the measurement results output from the sensor 4. Specifically, the measurement unit 5 acquires data on the reflected wave frequency [Hz] at each measurement time interval Δt.

[0032] When the measurement unit 5 acquires data on the reflected wave frequency from the sensor 4, the measurement unit 5 associates the data with the elapsed time (tick [seconds]) from a predetermined point in time specified by a clock function (not shown) provided in the measurement unit 5.

[0033] Then, the measurement unit 5 outputs combined data of the elapsed time (tick [seconds]) and the reflected wave frequency (Hz) for each measurement time interval Δt.

[0034] The predetermined time point that serves as the reference for the elapsed time tick [seconds] is not limited to a specific time point, and may be, for example, the time point when the boat speed meter 1 is activated.

[0035] The ship speed calculation unit 6 has the function of calculating the ship speed through water using data acquired by the measurement unit 5, and includes an instantaneous ship speed calculation unit 61, an abnormal value determination unit 62, a ship speed value calculation unit 63, an update determination unit 64, and a reference acceleration calculation unit 65.

[0036] The instantaneous vessel speed calculation unit 61 calculates the vessel's instantaneous speed through the water (referred to as "instantaneous vessel speed") using data acquired by the measurement unit 5 (step S1).

[0037] The instantaneous ship speed calculation unit 61 receives combined data of elapsed time ticks and reflected wave frequencies output from the measurement unit 5, and uses the combined data to calculate the flow velocity component in the direction of sound wave emission by the sensor 4 (in other words, the flow velocity component in the measurement direction of the sensor 4) for each elapsed time tick, and calculates the flow velocity from the bow to the stern of the hull based on the flow velocity component, which is output as the instantaneous ship speed. Note that the instantaneous ship speed calculation unit 61 may also calculate the flow velocity in the left-right direction of the hull.

[0038] The frequency [Hz] of the sound waves emitted from the sensor 4 is known as a setting value of the sensor 4 or a control value by the measurement unit 5. Therefore, the difference between the frequency of the sound waves emitted from the sensor 4 and the frequency of the reflected waves of the sound waves reflected by floating objects in the water (specifically, plankton, etc.) (i.e., the Doppler frequency according to the relative speed) can be obtained.

[0039] The value of the instantaneous ship speed calculated using the combined data associated with the elapsed time tick [seconds], i.e., the value of the instantaneous ship speed at the elapsed time tick [seconds], is represented as "v_tick".

[0040] The specific method for calculating instantaneous ship speed is not limited to a specific method or procedure in this invention, and various known methods and procedures exist (see, for example, Patent Publication Nos. 61-099868, 2019-128219, and 2003-004846), so detailed explanation will be omitted here.

[0041] The instantaneous ship speed calculation unit 61 calculates the elapsed time (tick [seconds]) and the instantaneous ship speed (v) for each measurement time interval Δt. _ Outputs the combined data with tick[kn].

[0042] The abnormal value determination unit 62 determines the elapsed time (tick) and the instantaneous ship speed (value) output from the instantaneous ship speed calculation unit 61. v _ tick and the combined data are input, and the instantaneous ship speed value v _ It is determined whether the tick is abnormal or not (step S2).

[0043] Here, the time interval during which the boat speed value V [kn] is calculated in the processing of step S5 described later and the time interval during which the reference acceleration ar [kn / sec] is calculated in the processing of step S10 described later is called the "calculation time interval," and its value is represented as I. In the following explanation, the boat speed value V at the elapsed time "T+I" that is the calculation time interval I after a certain elapsed time T is _ An example will be described below in which T+I is calculated.

[0044] The calculation time interval I is not limited to a specific length of time, but is set to an appropriate length of time, taking into account, for example, the results obtained from a simulation that takes into account the type of ship speed meter 1 and various conditions related to the ship type and ship speed through water.

[0045] The calculation time interval I may be set to any time length within a range of, for example, about 0.5 to 5 seconds.

[0046] Specifically, the abnormal value determination unit 62 calculates the boat speed value V at the elapsed time T output from the boat speed value calculation unit 63. _ The reference acceleration ar_T for the elapsed time T output from the reference acceleration calculation unit 65 (the calculation of the ship speed value V and the reference acceleration ar will be described later) is input, and the elapsed time tick from the elapsed time "T+Δt" to "T+I" output from the instantaneous ship speed calculation unit 61 and the instantaneous ship speed value v _ The controller 100 receives input of data combined with the instantaneous boat speed v_tick and determines whether the instantaneous boat speed value v_tick is abnormal based on the boat speed value V_T and the reference acceleration ar_T.

[0047] The instantaneous boat speed value at the elapsed time "T+Δt×n" from the elapsed time "T+Δt" to "T+I" input to the abnormal value determination unit 62 is expressed as "v_T+nΔt", where n=1, 2, 3, . . . , k, and in this embodiment, Δt×k=I.

[0048] Regarding the processing of step S2, a threshold value for the upper limit of the change in acceleration from the reference acceleration ar [kn / sec] (referred to as the "upper acceleration threshold aut") and a threshold value for the lower limit of the change in acceleration from the reference acceleration ar (referred to as the "lower acceleration threshold alt") are set in advance.

[0049] The upper acceleration threshold aut [kn / sec] and the lower acceleration threshold alt [kn / sec] are not limited to specific values, but are set to appropriate values ​​taking into consideration the range of acceleration changes that are normally expected (in other words, normally possible) based on the type, performance, specifications, etc. The upper acceleration threshold aut and the lower acceleration threshold alt may be set to have the same absolute value, or may be set to have different absolute values.

[0050] Then, for each instantaneous ship speed value v_T+nΔt at elapsed time "T+Δt×n", the abnormal value determination unit 62 determines whether the acceleration (i.e., (v_T+nΔt-V_T) / (Δt×n; referred to as "acceleration related to instantaneous ship speed") at which the ship speed changes from the ship speed value V_T at elapsed time T to the instantaneous ship speed value v_T+nΔt at elapsed time "T+Δt×n" is within the range from the lower limit "ar_T-alt" of the change in acceleration from the reference acceleration to the upper limit "ar_T+aut" of the change in acceleration from the reference acceleration (see Figure 3).

[0051] That is, abnormal value determination section 62 determines whether or not the following mathematical expression 1 holds true. (Math 1) ar_T-alt≦(v_T+nΔt-V_T) / (Δt×n)≦ar_T+aut

[0052] The above equation 1 may be modified as shown in the following equation 2. (Number 2) V_T+(ar_T-alt)×(Δt×n)≦v_T+nΔt≦V_T+(ar_T+aut)×(Δt×n)

[0053] If the above formula 1 (or formula 2) does not hold (step S2: No), the abnormal value determination unit 62 determines that the instantaneous ship speed value v_T+nΔt is an abnormal value and excludes the instantaneous ship speed value v_T+nΔt from further processing (step S3).

[0054] On the other hand, if the above formula 1 (or formula 2) is true (step S2: Yes), the abnormal value determination unit 62 determines that the instantaneous ship speed value v_T+nΔt is a normal value (in other words, an acceptable value), and sets the instantaneous ship speed value v_T+nΔt as the value to be adopted in subsequent processing, and adds and stores the combined data of the elapsed time "T+Δt×n" and the instantaneous ship speed value v_T+nΔt at the beginning of the instantaneous ship speed buffer 31 (in other words, as the newest data in the chronological order) (step S4).

[0055] The instantaneous vessel speed buffer 31 is configured in the storage unit 3 and has the function of storing and accumulating combined data of elapsed time tick and instantaneous vessel speed value v_tick in chronological order (specifically, in descending order).

[0056] The instantaneous ship speed buffer 31 stores only the combination data of the elapsed time tick associated with the instantaneous ship speed value v_tick stored first (in other words, the newest in the chronological order) and the instantaneous ship speed value v for a predetermined period (in other words, a predetermined length of time), and the combination data prior to the predetermined period (in other words, older in the chronological order) is discarded.

[0057] The vessel speed value calculation unit 63 calculates the vessel speed value using the instantaneous vessel speed value stored in the instantaneous vessel speed buffer 31 (step S5).

[0058] The ship speed value calculation unit 63 reads the instantaneous ship speed values ​​v stored in the instantaneous ship speed buffer 31 at each calculation time interval I, calculates the average value of the instantaneous ship speed values ​​v, and outputs it as the ship speed value V[kn]. The ship speed value calculation unit 63 calculates the average value using the instantaneous ship speed values ​​v stored in the instantaneous ship speed buffer 31 at the point in time "T+I", for example, and sets this as the ship speed value V_T+I at the elapsed time "T+I". Note that the ship speed value calculation unit 63 may calculate, for example, a simple average value as the average value of the instantaneous ship speed values ​​v, or may calculate a weighted average value weighted by a value n representing the progress of elapsed time so that newer instantaneous ship speed values ​​v in the time series contribute more significantly.

[0059] As mentioned above, the instantaneous ship speed buffer 31 stores only the combined data of the elapsed time (in this embodiment, Δt×n) from the elapsed time tick associated with the instantaneous ship speed value v_tick stored first (in other words, the newest in the time series) for a predetermined period of time and the instantaneous ship speed value v, and the predetermined period is the time width (in other words, the averaging time) over which the instantaneous ship speed values ​​v are averaged when calculating the ship speed value V.

[0060] The time span for averaging the instantaneous ship speed values ​​v when calculating the ship speed value V (and also the time span for the instantaneous ship speed values ​​v stored in the instantaneous ship speed buffer 31) is not limited to a specific time span, but is appropriately set to an appropriate time span, taking into account, for example, the results obtained by a simulation that takes into account the method of the ship speed meter 1 and various conditions related to the ship type and ship speed through water.

[0061] The time span over which the instantaneous ship speed values ​​v are averaged when calculating the ship speed value V may be set to any time length within the range of, for example, about 1 to 60 seconds.

[0062] The vessel speed value calculation unit 63 outputs the data of the calculated vessel speed value V via the interface unit 7 for each calculation time interval I (step S6).

[0063] The interface unit 7 has the function of providing an input / output interface for the ship speed calculation unit 6, and for example, receives input data of the ship speed value V calculated by the ship speed value calculation unit 63, and displays and outputs the ship speed value V on the display unit 8.

[0064] The display unit 8 has a function of displaying various information including the boat speed value V output from the interface unit 7, and is configured as a mechanism including, for example, a liquid crystal display.

[0065] The update determination unit 64 determines whether or not the instantaneous vessel speed buffer 31 has been updated after the vessel speed value V was calculated in the previous processing (step S7).

[0066] For example, when the ship speed value V_T+I at elapsed time "T+I" is calculated, the update determination unit 64 determines that the instantaneous ship speed buffer 31 has not been updated if the combined data of the elapsed time tick and the instantaneous ship speed value v_tick stored at the beginning of the instantaneous ship speed buffer 31 at the elapsed time "T+I" (in other words, the newest in the chronological order) is the same as the combined data of the elapsed time tick and the instantaneous ship speed value v_tick stored at the beginning of the instantaneous ship speed buffer 31 at the elapsed time T (in other words, the newest in the chronological order), and determines that the instantaneous ship speed buffer 31 has been updated if they are different.

[0067] If the instantaneous vessel speed buffer 31 has not been updated (step S7: No), the update determination unit 64 excludes the vessel speed value calculated in this process (i.e., the vessel speed value V_T+I at elapsed time "T+I") from the target of subsequent processing (step S8).Then, the control unit 2 shifts the processing procedure for measuring the vessel's water speed (vessel speed through water) to the processing of step S1.

[0068] On the other hand, if the instantaneous ship speed buffer 31 has been updated (step S7: Yes), the update determination unit 64 sets the ship speed value calculated in this processing (i.e., the ship speed value V_T+I at elapsed time "T+I") as the value to be adopted in subsequent processing, and adds and stores the combined data of the elapsed time "T+I" and the ship speed value V_T+I at the beginning of the ship speed value buffer 32 (in other words, as the newest data in the chronological order) (step S9).

[0069] The ship speed value buffer 32 (which is a second buffer in that it is a different buffer from the instantaneous ship speed buffer 31) is configured within the memory unit 3 and has the function of storing and accumulating combined data of elapsed time and ship speed value V in chronological order (specifically, in descending order).

[0070] The boat speed value buffer 32 stores only a predetermined number of combinations of elapsed time and boat speed value V, and when the number of combinations exceeds the predetermined number, the oldest combinations are discarded in chronological order.

[0071] The reference acceleration calculation unit 65 calculates the reference acceleration ar using the boat speed value stored in the boat speed value buffer 32 (step S10).

[0072] The reference acceleration calculation unit 65 reads the combined data of the elapsed time and the ship speed value V stored in the ship speed value buffer 32 for each calculation time interval I, calculates the acceleration based on the range of the elapsed time (in other words, the time length) and the range of change in the ship speed value V, and outputs the calculated acceleration to the abnormal value determination unit 62 as the reference acceleration ar [kn / sec].

[0073] For example, after calculating the ship speed value V_T+I at the elapsed time "T+I", the reference acceleration calculation unit 65 calculates the acceleration using the combined data of the elapsed time and the ship speed value V stored in the ship speed value buffer 32 at that time, and sets the acceleration as the reference acceleration ar_T+I for the elapsed time "T+I".

[0074] In the example shown in Figure 3, the ship speed value V_T-I at elapsed time "TI" and the ship speed value V_T at elapsed time T are used to calculate the reference acceleration ar_T (= (V_T-V_T-I) / I) for the elapsed time T, and the reference acceleration ar_T for the elapsed time T is used to determine whether the instantaneous ship speed value v_T+nΔt at the elapsed time "T+Δt×n" from elapsed time "T+Δt" to "T+I" is abnormal, and then the ship speed value V_T+I at the elapsed time "T+I" is calculated.

[0075] Here, as mentioned above, only a predetermined number of combinations of elapsed time and ship speed value V are stored in the ship speed value buffer 32, and the predetermined number is not limited to a specific value, but is set to an appropriate value taking into consideration that a reasonable value can be calculated as the reference acceleration.

[0076] The number of combination data of elapsed time and boat speed value V stored in the boat speed value buffer 32 may be set to any value within the range of, for example, about two to four.

[0077] Then, the control unit 2 shifts the processing procedure for measuring the water speed of the vessel (ship speed through water) to the processing of step S1.

[0078] In addition, the control unit 2 repeats the processes from step S1 to step S10 and continues measuring and outputting the ship speed value V until it receives an instruction from the user via the interface unit 7 or a predetermined termination event occurs (for example, the ship stops).

[0079] According to the speed meter 1 and the speed measurement method of the embodiment, the speed value V is calculated using only the instantaneous speed value v for which the acceleration related to the instantaneous speed is within a predetermined range, so that the instantaneous speed value v based on an abnormal Doppler frequency can be eliminated when calculating the speed value V, and it becomes possible to obtain an accurate speed of the ship through the water. Furthermore, according to the speed meter 1 and the speed measurement method of the embodiment, since acceleration is used as the judgment criterion, the trend of the speed can be used as the judgment criterion, and it becomes possible to calculate the speed value V more naturally.

[0080] According to the ship speed meter 1 and ship speed measurement method of the embodiment, the reference acceleration ar is calculated based on the ship speed value V, which is calculated using the normal (in other words, within the acceptable range) instantaneous ship speed value v, making it possible to determine the accurate ship speed through water.

[0081] The above describes an embodiment of the present invention, but the specific configuration is not limited to the above embodiment, and even if there are design changes or the like within the scope of the gist of the present invention, they are included in the present invention.

[0082] For example, in the above embodiment, the speed meter 1 is configured to include the configuration and functions of an acoustic (Doppler) speed meter, but the type of speed meter to which this invention can be applied is not limited to the acoustic type, and this invention can be applied to various types of speed meter as long as they are a type of speed meter that can measure instantaneous speed as in the above embodiment.

[0083] Furthermore, in the above-described embodiment, the speed meter 1 measures the water speed of a ship, but the present invention can also be applied to measuring the ground speed (that is, the ground speed of a ship).

[0084] Furthermore, in the above embodiment, if the instantaneous vessel speed value v is deemed an abnormal value and is excluded from subsequent processing (step S2: No, step S3) repeatedly, the instantaneous vessel speed buffer 31 is not updated (step S7: No), and therefore the vessel speed value V calculated in the processing of step S5 will not change while the instantaneous vessel speed value v continues to be excluded and the instantaneous vessel speed buffer 31 is not updated. Therefore, as a countermeasure for when the instantaneous vessel speed value v continues to be excluded for a certain period of time, the lower limit "ar_T-alt" of the acceleration change from the reference acceleration may be set to 0 [kn / sec] (for example, when the vessel is moving forward), or the upper limit "ar_T+aut" of the acceleration change from the reference acceleration may be removed (i.e., no upper limit), or the lower limit "ar_T-alt" of the acceleration change from the reference acceleration may be removed (i.e., no lower limit) or the upper limit "ar_T+aut" of the acceleration change from the reference acceleration may be set to 0 [kn / sec] (for example, when the vessel is moving astern). In this case, for example, when a predetermined ship speed (which is not limited to a specific speed and may be set to a maximum speed based on the ship's performance and specifications or to 0) is reached when navigating at the last calculated reference acceleration ar, measures may be taken to deal with the situation where the instantaneous ship speed value v continues to be excluded. Alternatively, measures may be taken to deal with the situation where the instantaneous ship speed value v continues to be excluded when the instantaneous ship speed buffer 31 is not updated for a predetermined time (which is not limited to a specific time length and may be set to any time length in the range of approximately 5 to 15 seconds, for example). In other words, when the instantaneous ship speed value v stored in the instantaneous ship speed buffer 31 has not been updated and predetermined conditions are met, the conditions defining the range of acceleration related to the instantaneous ship speed (specifically, the lower limit of the change in acceleration from the reference acceleration "ar_T-alt" and the upper limit of the change in acceleration from the reference acceleration "ar_T+aut") may be changed.

[0085] Furthermore, in the above embodiment, when the instantaneous ship speed value v is determined to be a normal value (in other words, an acceptable value) and is to be adopted in subsequent processing (step S2: Yes), all of the instantaneous ship speed values ​​v are added to and stored in the instantaneous ship speed buffer 31 (step S4). However, the addition and storage to the instantaneous ship speed buffer 31 is not limited to this form. For example, the combined data of the average value of the instantaneous ship speed values ​​v adopted in the calculation time interval I (specifically, for example, from the elapsed time "T+Δt" to "T+I") and a representative value of the elapsed time (for example, T+I / 2) may be added to the beginning of the instantaneous ship speed buffer 31 and stored, or the combined data of the instantaneous ship speed value v adopted in the calculation time interval I (specifically, for example, from the elapsed time "T+Δt" to "T+I"), whose acceleration related to the instantaneous ship speed is closest to the reference acceleration, and a representative value of the elapsed time (for example, T+I / 2) may be added to the beginning of the instantaneous ship speed buffer 31 and stored. [Explanation of symbols]

[0086] 1 Speedometer 2. Control section 3 Storage section 31 Instantaneous ship speed buffer 32 Ship speed value buffer 4 sensors 5. Measurement section 6 Ship speed calculation section 61 Instantaneous ship speed calculation section 62 Abnormal value determination unit 63 Ship speed calculation unit 64 Update determination section 65 Reference acceleration calculation section 7 Interface section 8 Display

Claims

1. A ship speed meter that calculates the ship speed value at predetermined time intervals, a predetermined number of the ship speed values ​​calculated before the previous processing are stored in a second buffer, a reference acceleration is calculated at the predetermined time intervals using the ship speed values ​​stored in the second buffer, instantaneous speed values ​​of the ship measured between the previous processing and the current processing, whose accelerations related to the instantaneous speeds are within a predetermined range centered on the reference acceleration are stored in a buffer for a predetermined period, and a ship speed value in the current processing is calculated using the instantaneous speed values ​​stored in the buffer; The acceleration related to the instantaneous speed refers to the acceleration when the boat speed value calculated in the previous processing changes to the instantaneous speed value. A ship speed meter characterized by:

2. Only when the instantaneous velocity value stored in the buffer is updated, the acceleration to be used as a reference for the predetermined range is calculated.

2. A boat speed indicator according to claim 1.

3. changing the condition defining the predetermined range when a predetermined condition is satisfied in a situation where the instantaneous speed value stored in the buffer has not been updated; 3. A boat speed indicator according to claim 1 or 2.

4. The method for measuring the instantaneous velocity is an acoustic method.

4. A boat speed indicator according to claim 1.

5. A method for measuring ship speed, which calculates a ship speed value at predetermined time intervals, a predetermined number of the ship speed values ​​calculated before the previous processing are stored in a second buffer, a reference acceleration is calculated at the predetermined time intervals using the ship speed values ​​stored in the second buffer, instantaneous speed values ​​of the ship measured between the previous processing and the current processing, whose accelerations related to the instantaneous speeds are within a predetermined range centered on the reference acceleration are stored in a buffer for a predetermined period, and a ship speed value in the current processing is calculated using the instantaneous speed values ​​stored in the buffer; The acceleration related to the instantaneous speed refers to the acceleration when the boat speed value calculated in the previous processing changes to the instantaneous speed value. A method for measuring ship speed.

6. Only when the instantaneous velocity value stored in the buffer is updated, the acceleration to be used as a reference for the predetermined range is calculated.

6. A method for measuring boat speed according to claim 5.

7. changing the condition defining the predetermined range when a predetermined condition is satisfied in a situation where the instantaneous speed value stored in the buffer has not been updated; 7. A boat speed measuring method according to claim 5, wherein the speed of a boat is measured by the method.

8. The method for measuring the instantaneous velocity is an acoustic method.

8. A boat speed measuring method according to claim 5, wherein the speed of the boat is measured by the method.

Images