JP2019090645A - Log speed estimation device, log speed display device, periodic current measuring device, automatic navigation device, and method for estimating log speed - Google Patents

Abstract

To provide a log speed estimation device that can accurately estimate a log speed when a mobile body is in a transient state.SOLUTION: A log speed estimation device 8 includes: a log speed estimation unit 80 and an operational characteristics filter 81. The log speed estimation unit 80 estimates the log speed of the mobile body on water based on at least one parameter, and outputs the estimated log speed as an estimated log speed. The operational characteristics filter 81 corrects the estimated log speed input from the log speed estimation unit 80 by a calculation based on the operational characteristics of the mobile body, and outputs the estimated log speed having been corrected.SELECTED DRAWING: Figure 2

Description

  The present invention relates mainly to an apparatus for estimating the water velocity, which is the velocity of a moving body on water relative to water.

  Conventionally, a configuration for obtaining the water velocity using ultrasonic waves is known. For example, the tidal current measurement device disclosed in Patent Document 1 is configured to transmit an ultrasonic wave from a ship into water, and acquire the watercraft speed using the Doppler effect of the reflected wave. This tidal current measurement device calculates tidal current from the difference between the obtained ship-to-water ship speed and the absolute ship speed output by the navigation device using GPS or the like.

  Patent Document 2 points out the problem that the acoustic type water speedometer requires a large-scale mounting operation such as drilling a hole in the bottom of the ship in order to equip the ship with it. In order to solve this problem, the water velocity estimation device proposed by Patent Document 2 copes with conditions specified by a combination of information on propeller speed, wind direction, wind velocity, etc. that affect the water velocity vector of the ship. These values are estimated to be the ship's water velocity vector and output.

  The estimator of Patent Document 2 is configured using a neural network, and the coupling coefficient of the neural network is updated as needed so that the error between the output and the ground speed calculated using GNSS is reduced. Ground speed is affected by surface flow, which is the flow in the shallow part of water, but the size and direction of surface flow vary, so any size and direction of ground speed can be used for the same water speed. Contains surface flow velocity components. Therefore, when the coupling coefficient is repeatedly updated using the ground speed as the teacher signal, the influence of the surface flow becomes small at the stage where learning has sufficiently progressed, and the output of the estimator converges on the water speed.

JP, 2009-092578, A International Publication No. 2015/129337

  In the case of actually operating a ship, there are more steady states traveling at a constant ship speed than transient states in which acceleration / deceleration occurs. Therefore, when using the device for estimating the water velocity of Patent Document 2, the estimator is a steady state The case of learning at becomes dominant. Therefore, as learning progresses, the estimator outputs a value close to the steady state water velocity (i.e., the end water velocity) as an estimated value. On the other hand, since inertia acts on the ship, when the propeller speed is changed for acceleration / deceleration, the change in actual water velocity is usually delayed with respect to the change in propeller speed. Therefore, the water velocity estimation device of Patent Document 2 has room for improvement in that the estimation error of the water velocity increases in the transient state in which acceleration and deceleration are performed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a water velocity estimation device capable of accurately estimating the water velocity in the transient state of a moving object.

Means and effect for solving the problem

  The problem to be solved by the present invention is as described above, and next, means for solving the problem and its effect will be described.

  According to a first aspect of the present invention, an apparatus for estimating water velocity is provided as follows. That is, the water velocity estimation device includes a water velocity estimation unit and a motion characteristic filter. The water velocity estimation unit estimates the water velocity of the moving body on the water based on at least one parameter and outputs the estimated water velocity. The motion characteristic filter corrects the estimated water velocity input from the water velocity estimation unit by calculation based on the motion characteristics of the moving body, and outputs the corrected velocity as a corrected estimated water velocity.

  Thus, even if the water velocity estimation unit outputs the end velocity or a value close thereto as the estimated water velocity in the transitional condition where the moving object accelerates or decelerates, the mobile object in the transient condition is corrected by the correction of the motion characteristic filter. It is possible to properly reflect the influence of the movement characteristics of Therefore, it is possible to estimate the water velocity accurately, especially in transient conditions.

  In the above-described water velocity estimating apparatus, it is preferable that the calculation for the correction is performed by an equation including the mass of the moving body and a proportional coefficient which determines the magnitude of the water resistance.

  In this way, it is possible to estimate the water velocity by properly considering the mass and the water resistance.

  It is preferable to set it as the following structures in said water speed estimation apparatus. That is, the motion characteristic filter corrects the estimated water velocity by calculating based on an equation derived from an equation of motion. The equation of motion includes a term of force proportional to the square or cube of the velocity of water, as a term of resistance of water.

  This makes it possible to estimate the water velocity by properly considering the water resistance.

  In the above-described water velocity estimation device, it is preferable to include a parameter setting unit capable of setting the calculation parameter for the correction.

  As a result, even if the mass of the moving body changes due to, for example, loading and unloading of the cargo from the ship, the parameter can be changed according to the change, so that the water speed can be estimated accurately.

  In the above-described water velocity estimation device, it is preferable that the rotational velocity of the driving member included in the moving body is included in the parameter for the water velocity estimation unit to estimate the water velocity.

  Thereby, the water velocity can be appropriately estimated.

  In the above-described water velocity estimation device, the motion characteristic filter determines whether the moving body is in the acceleration state or the deceleration state based on the magnitude of the correction amount obtained by correcting the estimated water velocity. It is preferable to include a deceleration determination unit.

  As a result, whether or not the moving body is in the acceleration state or the deceleration state can be obtained with a simple configuration and can be used in various ways.

  In the water velocity estimating device, the moving object is accelerated or decelerated based on at least one of the ground velocity of the moving object and the corrected estimated water velocity output from the motion characteristic filter. It is preferable to include an acceleration / deceleration determination unit that determines whether or not there is an error.

  As a result, whether or not the moving body is in the acceleration state or the deceleration state can be obtained with a simple configuration and can be used in various ways.

  According to a second aspect of the present invention, a water velocity display apparatus having the following configuration is provided. That is, the water velocity display device includes a water velocity estimation device and a display unit. The display unit displays the corrected estimated water velocity.

  This can provide accurate water velocity information.

  According to a third aspect of the present invention, there is provided a tidal current measurement apparatus having the following configuration. That is, this tidal current measurement device includes the above-described water velocity estimation device, a ground velocity calculation unit, a tidal current measurement unit, and a tidal current measurement control unit. The ground speed calculation unit calculates the ground speed of the mobile unit. The tidal current measurement unit measures tidal current. The tidal current measurement control unit stops the measurement of tidal current by the tidal current measurement unit when the acceleration / deceleration determination unit determines that the moving body is in the acceleration state or the deceleration state.

  That is, when the moving body is in the acceleration state or the deceleration state, an error is likely to occur in the measurement result of the tidal current. Therefore, by stopping the measurement of the tidal current when the moving body accelerates or decelerates, it is possible to prevent the decrease in the tidal current measurement accuracy.

  It is preferable to set it as the following structures in said tidal current measurement apparatus. That is, the tidal current measurement device includes the drive member acceleration / deceleration determination unit. The drive member acceleration / deceleration determination unit determines whether the rotation of the drive member is in an acceleration state or a deceleration state based on a change in rotational speed of the drive member provided for propulsion by the movable body. The tidal current measurement control unit stops the measurement of the tidal current by the tidal current measurement unit when the drive member acceleration / deceleration determination unit determines that the rotation of the drive member is in the acceleration state or the deceleration state.

  Thereby, it can be simply determined based on the change of the rotational speed of the drive member whether or not the measurement of the tidal current should be stopped.

  It is preferable to set it as the following structures in said tidal current measurement apparatus. That is, the tidal current measurement device includes an azimuth detection unit and a turning state determination unit. The azimuth detection unit detects an azimuth in which the moving body is directed. The turning state determination unit determines, based on the change in the direction detected by the direction detection unit, whether the moving body is in the turning state. The tidal current measurement control unit stops the measurement of the tidal current by the tidal current measurement unit when the turning state determination unit determines that the moving body is in the turning state.

  Thus, it can be appropriately determined based on the change in the direction in which the moving body is facing whether or not the measurement of the tidal current should be stopped.

  According to a fourth aspect of the present invention, there is provided an automatic navigation apparatus having the following configuration. That is, this automatic navigation system includes the above-described water speed estimation device and a propulsion control unit. The propulsion control unit controls driving of a driving member provided in the moving body based on the corrected estimated water velocity.

  This enables automatic navigation of the mobile unit to be performed accurately.

  According to a fifth aspect of the present invention, the following method for estimating water velocity is provided. That is, based on at least one parameter, the velocity of the mobile on the water is estimated. The estimated water velocity is corrected by calculation based on the movement characteristic of the moving body.

  In this way, in the transitional state where the moving body accelerates and decelerates, the influence of the movement characteristic of the moving body in the transitional state is appropriately applied even when the water speed estimation unit outputs the terminal speed or a value close thereto as the estimated water speed. It is possible to make corrections reflected in Therefore, it is possible to estimate the water velocity accurately, especially in transient conditions.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the structure of the automatic navigation apparatus which concerns on one Embodiment of this invention. The block diagram which shows the structure of a tidal current measurement apparatus. The graph which shows the result of the experiment which used the movement characteristic filter.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an automatic navigation device 100 according to an embodiment of the present invention.

  The automatic navigation device 100 shown in FIG. 1 is mounted on a not-shown vessel (mobile on water), and can perform control to automatically navigate the vessel. The automatic navigation device 100 includes a GNSS positioning unit 1, a propeller rotation speed detection unit 2, a wind direction / speed detection unit 3, a direction detection unit 12, a propulsion control unit 5, a tidal current measurement device 6, and a ground speed calculation unit 7. , A water velocity estimation device 8, and a tidal current measurement unit 9.

  The ship is provided with a display unit 4, and the display unit 4 is electrically connected to a computer described later provided in the automatic navigation device 100. A water speed display device 15 is configured by the water speed estimation device 8 and the display unit 4. The water speed display device 15 can obtain the water speed of the ship and display it on the display unit 4.

  Ground velocity calculation unit 7, water velocity estimation device 8, tidal current measurement unit 9, propeller acceleration / deceleration determination unit (drive member acceleration / deceleration determination unit) 10, turning state determination unit 13, tidal current measurement control unit 11 , The tidal current measurement device 6 is configured. The tidal current measurement device 6 can measure the tidal current, and can output the measurement result to, for example, the display unit 4 for display.

  The GNSS positioning unit 1 is configured of, for example, a GNSS receiver. The GNSS positioning unit 1 can perform positioning by receiving a positioning signal transmitted from a satellite (not shown). GNSS (Global Navigation Satellite System) is a generic term for positioning systems using satellites. Examples of GNSS include satellite positioning systems established by respective countries and regions, such as GPS in the United States, GLONASS in Russia, Galileo in Europe, BeiDou in China, QZSS in Japan, Gagan in India, and the like.

  Since the method of GNSS positioning is known, the description is omitted. Due to the nature of GNSS positioning, the position output by the GNSS positioning unit 1 indicates an absolute position relative to the earth.

  The propeller rotation number detection unit 2 is configured of, for example, a pulse type, electromagnetic type, optical type rotation sensor (sensor capable of detecting the number of rotations). The propeller rotation number detection unit 2 can detect the number of rotations per unit time of the propeller (drive member) 20 that generates the propulsion force of its own ship, in other words, the rotation speed.

  The wind direction and wind speed detection unit 3 includes, for example, a wind direction and anemometer in which a vertical tail and a propeller are attached to a rotatable main body. When the vertical tail receives a wind, the main body rotates so that the propeller points upwind. Therefore, the wind direction can be detected from the direction of the main body at this time, and the wind speed can be detected from the rotational speed of the propeller.

  Since the anemometer is installed on the ship, the output wind direction and wind speed are relative to the own ship. In this respect, the wind direction and wind speed detection unit 3 is provided with a not-illustrated calculation device, which calculates the wind direction wind speed (true wind direction wind speed) based on the earth based on the wind direction and wind speed input from the wind direction anemometer. calculate. This conversion can be performed using a known method by inputting the information on the heading of the own ship relative to the earth and the information on the velocity into the calculation device. The heading information can be obtained by an appropriate orientation sensor (eg, a gyro compass or a GNSS compass). Information on the speed of the ship (speed based on the earth, which may hereinafter be referred to as ground speed) can be obtained, for example, by calculating the change in position obtained by the above GNSS positioning. .

  The azimuth detecting unit 12 includes a plurality of GNSS antennas fixed to the ship, and detects an azimuth (heading direction) in which the ship is facing based on the relative positional relationship of the GNSS antennas. In addition, the azimuth | direction detection part 12 is not limited to said structure, For example, a magnetic sensor, a gyro compass, etc. can also be used.

  The display unit 4 is configured of, for example, a liquid crystal display, and displays various pieces of information regarding boat maneuvering. As information displayed on the said display part 4, ground speed, water speed, tidal current value etc. can be mentioned, for example. The above information displayed on the display unit 4 is updated according to the information data input every predetermined time.

  The propulsion control unit 5 controls the rotation (drive) of the propeller 20 in accordance with the boat speed instructed by the boat operator, the corrected estimated water velocity output from the water velocity estimation device 8 described later, and the like. The propulsion control unit 5 can be realized, for example, by executing a program stored in advance.

  The tidal current measurement device 6 measures the tidal current at the own ship position every predetermined time based on the information input from the GNSS positioning unit 1, the propeller rotation speed detection unit 2, and the wind direction / speed detection unit 3.

  The ground speed calculation unit 7 calculates the ground speed of the own ship based on the change in the position of the own ship output by the GNSS positioning unit 1. The ground speed calculation unit 7 outputs the calculated ground speed to the water speed estimation device 8 and the tidal current measurement unit 9.

  The water speed estimation device 8 estimates the water speed of the ship on the basis of the propeller rotation speed input from the propeller rotation speed detection unit 2 and the true wind direction wind speed input from the wind direction and wind speed detection unit 3. In addition, in the process of performing the above estimation, the anti-water velocity estimating device 8 can determine whether the ship is accelerating or decelerating.

  The to-water velocity estimating device 8 is configured to estimate the to-water velocity by machine learning. For this learning, the to-the-ground velocity is input from the to-the-ground velocity calculating unit 7 to the to-the-water velocity estimating device 8.

  Although the details will be described later, the water velocity estimated by the water velocity estimating device 8 by machine learning is always close to the terminal velocity. Therefore, the water velocity estimation device 8 corrects the estimated water velocity so as to reduce the estimation error in the transient state in which the ship accelerates and decelerates. In the following description, the water velocity before correction may be referred to as estimated water velocity, and the water velocity after correction may be referred to as corrected estimated water velocity.

  The water velocity estimation device 8 outputs the estimated water velocity to the tidal current measurement unit 9 and outputs the corrected estimated water velocity to the display unit 4. Further, the anti-water velocity estimation device 8 outputs the determination result of the acceleration / deceleration of the ship to the tidal current measurement control unit 11.

  The tidal current measurement unit 9 calculates the tidal current by calculation based on the ground velocity input from the ground velocity calculation unit 7 and the estimated water velocity input from the water velocity estimation device 8.

  Tidal current means the speed at which the water in the area where the ship floats moves relative to the earth. The ground speed is expressed by the sum of the tidal current and the water speed, when the tidal current, the ship's water speed, and the ground speed are respectively represented by vectors. Therefore, the tidal current can be obtained by subtracting the estimated water velocity from the ground velocity. The tidal current acquired by the tidal current measurement unit 9 is output to the display unit 4. However, the tidal current acquired by the tidal current measurement unit 9 is based on the bow direction. Therefore, for example, when displaying the tidal current based on the north direction on the display unit 4, the tidal current measurement unit 9 determines the tidal current obtained based on the heading detected from the direction detection unit 12 as a reference for the north direction. Convert to

  The propeller acceleration / deceleration determination unit 10 increases the rotational speed of the propeller 20 based on whether or not the magnitude of the change in the rotational speed of the propeller 20 detected by the propeller rotational speed detection unit 2 is equal to or greater than a predetermined threshold. It can be determined whether the vehicle is in the accelerating state or the decelerating state in the decreasing state. It is to be noted that while the above-described water velocity estimation device 8 (in other words, the acceleration / deceleration determination unit 82 described later) determines the acceleration / deceleration at which the ship actually moves, the propeller acceleration / deceleration determination unit 10 The difference is that the acceleration / deceleration of the rotation is determined. The magnitude of the change in rotational speed of the propeller 20 can be obtained, for example, by differentiating the rotational speed or calculating the difference between the current rotational speed and the rotational speed before a predetermined time. The propeller acceleration / deceleration determination unit 10 outputs the obtained determination result to the tidal current measurement control unit 11.

  It is determined whether or not the vessel is in the turning state based on whether or not the magnitude of the change in the heading detected by the heading detection unit 12 is equal to or greater than a predetermined threshold. it can. The magnitude of the change in the heading can be obtained, for example, by differentiating the heading angle or calculating the difference between the current heading angle and the heading angle a predetermined time ago. The turning state determination unit 13 outputs the obtained determination result to the tidal current measurement control unit 11.

  The tidal current measurement control unit 11 is a motion state of the ship input from the water velocity estimation device 8 (specifically, a steady state in which a constant speed navigation or stop is being performed, or a transient in which acceleration or deceleration is performed). Depending on whether it is in the state, execution / stop of measurement of the tidal current in the tidal current measurement unit 9 is switched. Specifically, the tidal current measurement control unit 11 stops the measurement of the tidal current by the tidal current measurement unit 9 in the acceleration / deceleration state of the ship in which the measurement error of the tidal current tends to occur.

  Further, the tidal current measurement control unit 11 switches between the execution / stop of the measurement of the tidal current by the tidal current measurement unit 9 according to the state related to the acceleration / deceleration of the propeller 20 input from the propeller acceleration / deceleration determination unit 10. That is, when the propeller 20 is in the acceleration / deceleration state, the tidal current measurement control unit 11 stops the measurement of the tidal current by the tidal current measurement unit 9.

  Then, the tidal current measurement control unit 11 stops the measurement of the tidal current by the tidal current measurement unit 9 even in a turning state of the ship in which a tidal current measurement error easily occurs. That is, the tidal current measurement control unit 11 switches the measurement execution / stop of the tidal current by the tidal current measurement unit 9 according to the state related to the turning received from the turning state determination unit 13.

  As described above, since the tidal current measurement control unit 11 stops the measurement of the tidal current by the tidal current measurement unit 9 in the transient state in which the ship is accelerating or decelerating or the like, the fall of the tidal current measurement accuracy is prevented. can do.

  The propulsion control unit 5, the ground speed calculation unit 7, the water speed estimation device 8, the tidal current measurement unit 9, the propeller acceleration / deceleration determination unit 10, and the tidal current measurement control unit 11 are realized by a computer included in the automatic navigation device 100. There is. Specifically, the computer has a known configuration including a CPU, a ROM, a RAM, and the like, and the above-mentioned ROM stores a program for realizing the water speed estimation method and the like of the present invention. By the cooperation of the hardware and software, the automatic navigation device 100 includes the propulsion control unit 5, the ground speed calculation unit 7, the water speed estimation device 8, the power flow measurement unit 9, the propeller acceleration / deceleration determination unit 10, and the power flow measurement. It can function as the control unit 11 or the like.

  Subsequently, the water velocity estimation device 8 will be described in detail with reference to FIG. FIG. 2 is a block diagram showing the configuration of the tidal current measurement device 6 according to the embodiment of the present invention.

  As shown in FIG. 2, the water velocity estimation device 8 includes a water velocity estimation unit 80, a motion characteristic filter 81, an acceleration / deceleration determination unit 82, and a parameter setting unit 83.

  The water velocity estimation unit 80 is configured using a neural network. The water velocity estimation unit 80 has a configuration similar to that of the estimator disclosed in Patent Document 2 and thus will not be described in detail, but is a general configuration having an input layer, a hidden layer, and an output layer. In each layer, a plurality of units simulating brain cells are arranged.

  There are three input units constituting the input layer, and the rotational speed of the propeller, the component in the bow direction of the true wind direction velocity, and the component in the direction perpendicular to the bow direction are input. There are two output units constituting the output layer, which output a component in the bow direction of the water velocity and a component in the direction perpendicular to the bow direction, respectively. A hidden layer is disposed between the input layer and the output layer, and the hidden layer is constituted by an appropriate number of intermediate units. Information flows in the order of the input layer, the hidden layer, and the output layer.

  Each input unit and each intermediate unit are coupled by a path through which information flows, and each intermediate unit and each output unit are coupled by a path through which information flows. In each path, the influence (weight) that the information of the upstream unit gives to the information of the downstream unit is set.

  The ground speed is input to the ground speed estimation unit 80 from the ground speed calculation unit 7. The to-water velocity estimation unit 80 decomposes the input ground velocity into a component in the bow direction and a component in the direction perpendicular to the bow direction, based on the information on the heading of the own ship acquired separately.

  The water velocity output by the output layer in response to each information being input to the input layer is the ground velocity as a teacher signal input from the ground velocity calculating unit 7 and for each output unit (in other words, for each component) ) Are compared to determine the error. The water velocity estimation unit 80 updates the above weights by an error back propagation method which is a known algorithm so as to reduce this error. Learning can be realized by continuously performing the above processing.

  As described in Patent Document 2, the ground speed when the water speed is the same includes tidal current components of all magnitudes and directions. Therefore, by continuing the supervised learning with the ground signal as the correct answer, the influence of the tidal current component included in the ground speed gradually decreases, and the output of the water speed estimation unit 80 converges on the water speed. Therefore, it can be said that the to-water velocity estimation unit 80 substantially learns to-water velocity while using the to-ground velocity as a teacher signal.

  As described above, the parameters input to the water velocity estimation unit 80 to estimate the water velocity include the rotational velocity of the propeller 20 provided in the ship. Thereby, the water velocity can be appropriately estimated.

  The motion characteristic filter 81 is configured to correct the estimated water velocity input from the water velocity estimation unit 80 by performing a calculation based on the motion characteristics of the ship. The motion characteristic filter 81 outputs the corrected estimated water velocity (the above-described corrected estimated water velocity) to the acceleration / deceleration determination unit 82, the display unit 4, and the propulsion control unit 5.

  In general, when a ship is to be navigated, there are more states (steady state) at a constant speed than in a state in which acceleration / deceleration is being performed (transient state). Therefore, since the water velocity estimation unit 80 virtually learns only the relationship between the propeller speed and the water velocity in the steady state, the water velocity in the steady state, that is, the terminal velocity is estimated. Will be output as In this sense, it can be said that the water velocity estimation unit 80 is a water end velocity estimation unit. On the other hand, in the case of a ship under navigation, for example, when the propeller speed is changed to accelerate or decelerate, the timing at which the water velocity of the ship actually changes and reaches the terminal speed changes the propeller speed. Delay with respect to timing.

  In this respect, in the present embodiment, the motion characteristic filter 81 appropriately corrects the influence of the motion characteristic of the ship on the basis of the equation of motion with respect to the water velocity output by the water velocity estimation unit 80. Do. As a result, the anti-water velocity estimation device 8 can estimate the anti-water velocity in a manner that appropriately reflects the inertia and the like at the time of acceleration and deceleration. The specific calculation performed by the motion characteristic filter 81 will be described later.

  The acceleration / deceleration determination unit 82 causes the ship to accelerate or decelerate based on the estimated water velocity estimated by the water velocity estimation unit 80 and the corrected estimated water velocity corrected by the motion characteristic filter 81. Determine if there is. Specifically, the acceleration / deceleration determination unit 82 determines that the ship is accelerating or decelerating when the difference between the estimated water velocity and the corrected estimated water velocity is equal to or greater than a predetermined threshold. . The acceleration / deceleration determination unit 82 outputs the obtained determination result to the tidal current measurement control unit 11.

  The parameter setting unit 83 is configured to be able to set parameters of an equation of motion used for the motion characteristic filter 81. This parameter can be, for example, a value (k / M) obtained by dividing the proportionality coefficient k which determines the magnitude of the resistance of water by the hull mass M according to a formula described later. However, the parameter setting unit 83 may be configured to set the proportionality coefficient k and the hull mass M as parameters.

  In ship kinematics, when an object on water moves, it is known that an effect occurs as if the mass of the object increased more than the actual amount (added mass effect). The above-mentioned hull mass M means that including the mass thus apparently added (apparent mass).

  Subsequently, the correction in the motion characteristic filter 81 will be described in detail.

  The motion characteristic filter 81 performs calculation based on an equation of motion that holds true for a ship traveling at a ship speed v by assuming that the force by the resistance of water is proportional to the square or cube of v. This makes it possible to estimate the water velocity by properly considering the water resistance.

  Whether the force due to the resistance of water is proportional to the square of the boat speed v or the cube can be determined mainly in consideration of the size of the hull. For example, in a large tanker or the like, it may be considered to be proportional to the cube of the ship speed v, and to be proportional to the square of the ship speed v otherwise. In addition, based on the magnitude | size of said hull mass M, the motion equation to be used can also be selected and used from said 2 types.

ただし、
Ｍ：船体質量
Ｆ：船体に加える外力（プロペラ２０による推進力及び風による推力又は抵抗力）
ｖ：対水速度
ｔ：時刻
ｋ：比例係数
である。 The equation of motion in the bow direction when it is assumed that the force due to water resistance is proportional to the square of the boat speed v is expressed by the following equation (1). In the case where the ship is traveling forward at the ship speed v by the propulsive force of the propeller 20, the front of the ship is made positive.

However,
M: hull mass F: external force applied to the hull (propulsive force by propeller 20 and thrust or resistance by wind)
v: Water velocity t: Time k: Proportional coefficient.

ただし、ｖ≧０である。また、上記の条件より、Ｆ≧０であることから、ｖ_ter≧０である。 In the above equation (1), if t → 定 常, a steady state is obtained. _Assuming that the terminal velocity of the ship in this steady state is v _ter , by setting dv / dt = 0 in the above equation (1), it is represented by the following equation (2).

However, v ≧ 0. Further, according to the above condition, since _V00 , v _{ter 00} .

Further, when equation (1) is modified, equation (3) below is obtained.

The following equation (4) is obtained from the above equations (2) and (3).

The direction of the current water velocity v and the direction of the terminal velocity v _ter can be variously considered. Considering the case of v ≧ 0 and v _ter <0, v <0 and v _ter 0,0, v <0 and v _ter <0, equation (4) becomes equation (5) below.

This equation (5) is a differential equation with k / M as a ship-specific parameter. Since v _ter is obtained by the estimation of the water velocity estimation unit 80, if k / M is determined, the equation (5) is used to calculate the water velocity during acceleration / deceleration (corrected estimation relative to water velocity). can do.

ただし、Δｔはサンプリングの時間間隔である。 There are various methods for solving the equation (5) numerically, but for example, the explicit Euler method can be used. In the Euler method, the following approximate expression (6) is used.

However, Δt is a time interval of sampling.

The following equation (7) is obtained from the above equation (5) and equation (6).

This equation (7) indicates that the ship speed v _t at time t can be calculated by the ship speed v _t -Δt at time _t-Δt and the terminal speed v _ter . Although the equation of motion described above is in the bow direction, this equation (7) holds not only in the bow direction but also in the direction perpendicular to the bow direction.

The motion characteristic filter 81 is configured as an IIR filter that performs the calculation of the equation (7) derived in this way. The motion characteristic filter 81 substitutes the estimated water velocity into the terminal velocity v _ter of equation (7) every time the estimated water velocity is input from the water velocity estimator 80, and calculates the boat velocity v _t I do. This makes it possible to obtain a corrected estimated water velocity.

For example, in the equation at the top of Equation (7), in the steady state, v _ter and v _{t −Δt} substantially match, so the second term (correction term) on the right side becomes almost zero. On the other hand, in the transient state in which acceleration and deceleration are being performed, the difference between v _ter and v _{t -Δt} becomes large, so the second term (correction term) on the right side becomes large. Therefore, the motion characteristic filter 81 can perform necessary correction when the ship is in a transitional state in which acceleration and deceleration are performed.

  The equation (7) includes the hull mass M and a proportionality coefficient k representing the magnitude of the resistance of water. Therefore, it is possible to estimate the water velocity by properly considering the ship's mass and the water resistance.

  The value of k / M in Expression (7) can be obtained from the parameter set by the parameter setting unit 83. For example, k / M can be determined in an appropriate conversion formula from the hull length, the hull width, and the like of the target vessel, and can be set in the parameter setting unit 83. In addition, it is possible to measure the actual speed transition at the time of acceleration / deceleration of the ship with a boat speed meter, and to obtain the value of k / M by so-called fitting on the basis of this speed transition.

  The set value of the parameter setting unit 83 is configured to be changeable at an appropriate timing. Therefore, even if the mass of the ship changes due to, for example, unloading of cargo in a cargo ship, it is possible to accurately estimate the speed against water according to the situation by changing the parameter according to the change.

  The aforementioned acceleration / deceleration determination unit 82 accelerates or decelerates the ship based on the difference between the estimated water velocity output from the water velocity estimation unit 80 and the corrected estimated water velocity output from the motion characteristic filter 81. It is determined whether or not it is a state. In other words, the acceleration / deceleration determination unit 82 performs the above-described determination based on the magnitude of the correction amount obtained by correcting the estimated water velocity by the motion characteristic filter 81. This makes it possible to obtain with a simple configuration whether or not the hull is accelerating or decelerating.

  Subsequently, various experiments performed using the above-described motion characteristic filter 81 will be described with reference to FIG. FIG. 3 is a graph showing the results of an experiment using the motion characteristic filter 81.

  In the graph of FIG. 3A, the estimated water velocity (terminal velocity) input to the motion characteristic filter 81 is 0 knot from 0 seconds to 150 seconds, but approximately 16 from 150 seconds to 350 seconds. A change in the output value of the motion characteristic filter 81 is shown in the case where simulated data that becomes knots and becomes 0 knots again after 350 seconds is input. The value of k / M in the above equation (7) is about 0.017.

  From FIG. 3 (a), it is confirmed that the change in the water velocity (corrected estimated water velocity) output by the motion characteristic filter 81 is delayed compared to the input at both acceleration and deceleration. it can. Further, in the output value of the motion characteristic filter 81, the time until the boat speed reaches the terminal velocity after deceleration is longer than the time until the boat velocity reaches the terminal velocity after acceleration, which is It is a good representation of the ship's real motion characteristics.

  The graph in FIG. 3 (b) shows the output value of the water velocity estimation unit 80 and the ground velocity obtained by the GNSS positioning when the fishing boat is actually made to travel in an area where there is almost no tidal current and an experiment is conducted. Changes in the output value of the motion characteristic filter 81 are shown. The fishing boat was advanced at about 21 knots from 0 seconds to 190 seconds, then rapidly decelerated at the border of 190 seconds and finally stopped almost. Since there was almost no tidal current, the water velocity can be regarded as equal to the ground velocity shown in the graph. In this experiment, the value of k / M was about 0.027.

  As shown in FIG. 3B, the output value of the water velocity estimation unit 80 changes at an earlier timing relative to the change of the ground velocity, particularly in a portion surrounded by a dashed line. On the other hand, it can be seen that the output value of the motion characteristic filter 81 shows a value closer to the ground speed (in other words, the water speed).

  In the graph of FIG. 3 (c), the case where the same experiment as that of FIG. 3 (b) is performed by another ship is shown. In this experiment, the ship alternated forward navigation and stop while increasing the target speed each time. This experiment is also conducted in the sea area where there is almost no tidal flow. In this experiment, the value of k / M was about 0.071.

  As shown in the graph of FIG. 3 (c), the output value of the motion characteristic filter 81 is closer to the ground than the output value of the water velocity estimation unit 80, which is the value before correction, in both acceleration and deceleration. It is close to the velocity (water velocity). This confirms that the correction by the motion characteristic filter 81 is advantageous for improving the estimation accuracy of the water velocity.

  As described above, the water velocity estimation device 8 according to this embodiment includes the water velocity estimation unit 80 and the motion characteristic filter 81. The water speed estimation unit 80 estimates the water speed of the ship based on at least one parameter and outputs the estimated water speed. The motion characteristic filter 81 corrects the estimated water velocity input from the water velocity estimation unit 80 by calculation based on the ship motion characteristics, and outputs the corrected velocity as a corrected estimated water velocity.

  Thus, even if the water velocity estimation unit 80 outputs the terminal velocity or a value close thereto as the estimated water velocity in the transient condition where the ship accelerates or decelerates, the ship in the transient condition is corrected by the correction of the motion characteristic filter 81. It is possible to properly reflect the influence of the movement characteristics of Therefore, it is possible to estimate the water velocity accurately, especially in transient conditions.

  Further, the water velocity display device 15 according to the present embodiment includes the water velocity estimation device 8 and the display unit 4. The display unit 4 displays the corrected estimated water velocity.

  This allows, for example, the operator to be provided with an accurately estimated water velocity.

  Further, the tidal current measurement device 6 of the present embodiment includes a to-water velocity estimation device 8, a ground velocity calculating unit 7, a tidal current measuring unit 9, and a tidal current measurement control unit 11. The ground speed calculation unit 7 calculates the ground speed of the ship. The tidal current measurement unit 9 measures tidal current. The tidal current measurement control unit 11 stops the measurement of tidal current by the tidal current measurement unit 9 when the acceleration / deceleration determination unit 82 determines that the ship is in the acceleration state or the deceleration state.

  That is, when the ship is in the acceleration state or the deceleration state, an error is likely to occur in the measurement result of the tidal current. Therefore, when the ship accelerates or decelerates, the measurement accuracy of the tidal current can be prevented from being lowered by stopping the measurement of the tidal current.

  In addition, the automatic navigation device 100 of the present embodiment includes a water velocity estimation device 8 and a propulsion control unit 5. The propulsion control unit 5 controls the drive of the propeller 20 provided in the ship based on the corrected estimated water velocity.

  As a result, regardless of the transient state and the steady state of the ship, it is possible to appropriately estimate the water velocity and perform the automatic navigation properly.

  The preferred embodiment of the present invention has been described above, but the above-described configuration can be modified, for example, as follows.

  The water velocity estimation device 8 can also output a corrected estimated water velocity to the tidal current measurement unit 9 instead of the estimated water velocity. In this case, the tidal current measurement unit 9 measures the tidal current based on the corrected estimated water velocity. As described above, when the difference between the estimated water velocity and the corrected estimated water velocity is equal to or greater than a predetermined threshold, the tidal current measurement unit 9 stops the measurement. Therefore, while the tidal current measurement unit 9 executes the tidal current measurement, the measurement result does not change much regardless of which one is used.

  The tidal current measurement control unit 11 may be configured to stop the measurement of the tidal current not only in the acceleration / deceleration state but also in a state in which the heading is changing.

  The tidal current measurement control unit 11 may be omitted, and the tidal current measurement unit 9 may be configured to measure the tidal current based on the estimated water velocity or the corrected estimated water velocity in any of the steady state and the transient state.

  The determination result of the acceleration / deceleration determination unit 82 can be used not only for switching the measurement execution / stop of the tidal current measurement unit 9 but also for various other purposes. For example, it is possible to use the determination result of the acceleration / deceleration determination unit 82 in order to cause only the learning in the steady state to be performed by the water velocity estimation unit 80 after learning by the water velocity estimation unit 80 has progressed to a certain extent.

  The acceleration / deceleration determination unit 82 may make the determination based on the correction amount input from the motion characteristic filter 81 instead of the estimated and corrected water velocity input from the motion characteristic filter 81. This correction amount can be, for example, a value corresponding to the second term of the right side of the above-mentioned equation (7).

  The acceleration / deceleration determination unit 82 can also determine whether or not the vehicle is in the acceleration state or the deceleration state based on, for example, the ground speed or the corrected estimated water speed output from the motion characteristic filter 81.

  The water speed estimation unit 80 is not limited to the configuration using a neural network. For example, the water speed estimation unit 80 associates the combination of the input propeller rotation speed and the true wind direction and the wind speed with the input ground speed and stores them in an appropriate storage unit, and corresponds to the above combination. It may be configured to output an average value of a plurality of ground speeds stored in advance. Also according to this configuration, as the learning progresses, the influence of the tidal current component gradually decreases due to the averaging of the ground speed, and the output value substantially converges to the water speed.

  Further, the water velocity estimation unit 80 may be configured to estimate the water termination velocity based on, for example, a mathematical model without performing learning.

  Other parameters may be input to the water velocity estimation unit 80 instead of or in addition to the propeller speed and the true wind direction velocity.

DESCRIPTION OF SYMBOLS 4 Display part 5 Propulsion control part 6 Tidal current measurement apparatus 8 Water speed estimation apparatus 9 Tidal current measurement part 11 Tidal current measurement control part 15 Water speed display apparatus 20 Propeller (drive member)
80 Water speed estimation unit 81 Motion characteristic filter 100 Automatic navigation system

Claims (13)

A water velocity estimation unit that estimates the water velocity of the moving object on the water based on at least one parameter and outputs it as the estimated water velocity;
A motion characteristic filter that corrects the estimated water velocity input from the water velocity estimating unit by calculation based on the motion characteristic of the moving body and outputs the corrected velocity as a corrected estimated water velocity;
An apparatus for estimating water velocity, comprising: The water velocity estimation device according to claim 1, wherein
The motion characteristic filter according to claim 1, wherein the motion characteristic filter performs the calculation for the correction according to an equation including a mass of a moving body and a proportional coefficient which determines a magnitude of resistance of water. The water velocity estimation device according to claim 1 or 2, wherein
The motion characteristic filter corrects the estimated water velocity by calculating based on an equation derived from an equation of motion,
The apparatus for estimating water velocity according to claim 1, wherein the equation of motion includes a term of force proportional to a square or cube of the velocity of water as a term of resistance of water. The water velocity estimation device according to any one of claims 1 to 3, wherein
A water velocity estimation device comprising a parameter setting unit capable of setting parameters of the motion characteristic. The water velocity estimation device according to any one of claims 1 to 4, wherein
The apparatus according to any one of the preceding claims, wherein the parameter for the water speed estimation unit to estimate the water speed includes the rotational speed of the drive member provided in the moving body. The water velocity estimation device according to any one of claims 1 to 5, wherein
The motion characteristic filter further includes an acceleration / deceleration determination unit that determines whether the moving body is in an acceleration state or a deceleration state based on the magnitude of the correction amount obtained by correcting the estimated water velocity. Water velocity estimation device. The water velocity estimation device according to any one of claims 1 to 5, wherein
The vehicle control apparatus further comprises an acceleration / deceleration determination unit that determines whether the mobile unit is in an acceleration state or a deceleration state based on at least one of the ground speed of the mobile unit and the corrected estimated water velocity. Water velocity estimation device. The water velocity estimation device according to any one of claims 1 to 7,
A display unit for displaying the corrected estimated water velocity;
A water velocity display device comprising: The water velocity estimation device according to claim 6 or 7;
A ground speed calculation unit that calculates the ground speed of the moving body;
A tidal current measurement unit that measures tidal current,
A tidal current measurement control unit for stopping the measurement of tidal current by the tidal current measurement unit when the acceleration / deceleration determination unit determines that the moving body is in the acceleration state or the deceleration state;
A tidal current measuring apparatus comprising: The tidal current measuring apparatus according to claim 9,
And a drive member acceleration / deceleration determination unit that determines whether the rotation of the drive member is in an acceleration state or a deceleration state based on a change in rotation speed of the drive member provided for propulsion by the movable body.
The tidal current measurement control unit stops measurement of tidal current by the tidal current measurement unit when the drive member acceleration / deceleration determination unit determines that the rotation of the drive member is in an acceleration state or a deceleration state. Tidal current measuring device. The tidal current measuring apparatus according to claim 9 or 10, wherein
An azimuth detection unit that detects an azimuth in which the moving body faces;
A turning state determination unit that determines whether the mobile unit is in a turning state based on a change in the direction output from the direction detection unit;
Equipped with
The tidal current measurement device, wherein the tidal current measurement control unit stops the measurement of tidal current by the tidal current measurement unit when the pivot state determination unit determines that the movable body is in the pivot state. The water velocity estimation device according to any one of claims 1 to 7,
A propulsion control unit that controls driving of a drive member provided in the moving body based on the corrected estimated water velocity;
An automatic navigation device comprising: Estimate the water velocity of the mobile on the water based on at least one parameter,
A method of estimating water velocity characterized by correcting the estimated water velocity by calculation based on the motion characteristic of the moving body.

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