JP4515230B2 - Moving object position estimation detection method, apparatus, and moving object position estimation detection program - Google Patents

Description

  The present invention relates to a moving body position detection method for detecting a position of a moving body by detecting a signal representing a physical quantity in three dimensions. In particular, it is for estimating and detecting the position of a moving body that is performing a constant velocity linear motion using a signal by an electric field.

Conventionally, as a method for detecting the position of a moving body, for example, a three-axis magnetic sensor is used to detect an orthogonal three-axis component of a magnetic signal generated by the ship, and Is calculated using the method of least squares. In this case, when the ship which is a moving body is equipped with a demagnetizing device, the magnetic signal generated by the ship is reduced, and position detection becomes difficult. Therefore, there is a method of detecting the relative position of the moving target based on the orthogonal three-axis component of the signal generated by the electric field generated by the ship (see, for example, Patent Document 1).
Japanese Patent No. 3395136 (FIG. 1)

  When estimating the position by the method as described above, it is assumed that the source of the electric field is a dipole (dipole), and the formula based on the dipole moment is used for the calculation. Then, the parameter is adjusted and determined so that a value obtained by actual measurement (hereinafter referred to as an actual measurement value) matches and satisfies this equation as much as possible by the least square method. Here, the fact that the electric field is generated from a dipole is effective when the distance between the moving body and the sensor can be regarded as sufficiently large compared to the distance between the plurality of electrodes of the moving body.

  However, for example, because the distance between the moving body and the sensor (detector) is short (about 100 m or less), the moving body is large, and the distance between the electrodes is long, the distance between the moving body and the sensor is between the electrodes of the moving body. When the distance becomes shorter than the distance, the above-described formula does not follow the actual condition. Therefore, even if the actual measurement value is matched with the equation, the parameter value is different from the true value, and the accuracy of the estimated position detection is lowered. Further, the signal due to the electric field that is actually input to the sensor includes the signal that is input after the signal due to the electric field emitted from the hull is affected by various environmental conditions. Although some of them cannot be ignored, the above method treats the signal from the electric field generated from the hull as being directly input to the sensor.

  Therefore, the present invention solves the above-described problems, and can estimate and detect the position of the moving object with high accuracy even if the distance between the moving object and the sensor is short or the moving object is large. It aims at providing the method etc. which can be performed.

  According to the estimation and detection method for position and the like according to the present invention, an electric field generated by a moving body is measured in time series, and the estimation detection unit applies a least square method using a residual from the digitized electric field data. The parameter value is determined such that the data value satisfies the theoretical formula relating to the point current source, and at least the current and / or future position of the moving object is estimated and detected based on the determined parameter value.

  In addition, the position estimation estimation method according to the present invention includes a step of digitizing an electric field signal generated by a moving body received by the detection unit for each component in three axial directions, and collecting the collected data in time series as data. Applying a least-squares method using a residual to determine the parameter value so that the data value satisfies the theoretical formula for the point current source, and at least based on the determined parameter value, Estimating and detecting a current and / or future position of the mobile body.

  In addition, the estimated position detection method according to the present invention measures the electric field generated by a ship navigating the sea surface or the sea as a moving body in time series, and from the electric field data digitized, the estimation detection means is Determine the value of the parameter that satisfies the expression expressed as the sum of the electric field component directly emitted and the electric field component based on the mirror image electrode virtually set with the seawater surface and sea bottom as the boundary, and based on the determined parameter value And at least a current and / or future position of the moving object is estimated and detected.

  In addition, in the position and the like estimation detection method according to the present invention, values are further determined for parameters including the electrical conductivity of seawater and the seabed.

  Also, the Gauss-Newton method is applied to the least square method used in the position estimation estimation method according to the present invention.

  In addition, the estimated position detection method according to the present invention further detects and detects the closest position with respect to the speed of the moving body and the reception position of the electric field signal.

  In addition, the position and the like estimation detection method according to the present invention determines the moving object or its type based on the electric field strength or the parameter value.

  According to the present invention, there is provided an apparatus for detecting and estimating a position and the like, a detection means for detecting an electric field by each component in three axial directions, a data recording means for recording a signal detected by the detection means in time series as electric field data, Until the value of the data satisfies the theoretical formula of the electric field related to the point current source, the parameter value is determined by performing the iterative calculation by the least square method using the residual until the predetermined convergence condition is satisfied, And a detection means for estimating and detecting at least a current and / or future position of the moving body based on the determined parameter value.

According to the present invention, there is provided an estimation detection apparatus for position and the like, a detection means for detecting an electric field with each component in three axial directions, a data recording means for recording a signal detected by the detection means in time series as electric field data, and data The value of the electric field data stored in the recording means is the electric field component directly generated from the sea surface which is a moving body or a ship navigating in the sea and the electric field component based on the mirror image electrode virtually set with the sea surface and the sea bottom as a boundary. The value of the parameter that satisfies the expression expressed by the sum of and is determined by applying the least square method using the residual, and at least the current and / or future position of the moving object based on the determined parameter value And detecting means for estimating and detecting.

  Moreover, the detection means of the position estimation estimation device according to the present invention further estimates and detects the speed of the moving object and the closest approach position to the detection means based on the parameter values.

Moreover, the detection means of the position estimation estimation apparatus according to the present invention determines the moving body or its type based on the strength of the electric field or the value of the parameter.

  In addition, the position estimation detection method program according to the present invention quantifies the electric field signal generated by the moving body and received by the detection unit for each component in the three-axis direction, and the data collected in time series as data. Applying a least square method using a residual and determining a parameter value so that the data value satisfies a theoretical formula relating to the point current source; and at least the moving object based on the determined parameter value And causing the computer to perform a process of estimating and detecting current and / or future positions.

  In addition, the program of the position and the like estimation detection method according to the present invention measures the electric field generated by the ship navigating the sea surface or the sea as a moving object in time series, and is directly emitted from the ship from the digitized electric field data. A step of determining a parameter value satisfying an expression represented by the sum of the electric field component and the electric field component based on a mirror image electrode virtually set with the sea surface and the sea bottom as a boundary, and based on the determined parameter value , And causing the computer to perform at least a step of estimating and detecting a current position and / or a future position of the moving body.

  Moreover, the program of the position estimation estimation method according to the present invention further causes the computer to determine values for parameters including the electrical conductivity of the seawater and the seabed.

  Further, the program of the estimation detection method for position and the like according to the present invention further causes the computer to perform estimation detection of the closest position with respect to the speed of the moving body and the reception position of the electric field signal based on the parameter values.

  In addition, the program of the position and the like detection method according to the present invention causes the computer to further determine the moving object or its type based on the strength of the electric field or the value of the parameter.

  According to the present invention, the estimation detection means determines a parameter value satisfying the theoretical formula relating to the point current source from the electric field data obtained by measuring the electric field generated by the moving body in time series, and the determined parameter value Since at least the current and / or future position of the moving body is estimated and detected based on the above, the position and the like can be accurately estimated and detected.

  In addition, according to the present invention, the estimation detection unit determines a parameter value that satisfies the theoretical formula relating to the point current source from electric field data obtained by measuring the electric field generated by the moving body in time series in three axes. Since at least the current and / or future position of the moving body is estimated and detected based on the determined parameter value, the position and the like can be estimated and detected accurately. This is particularly effective for estimating and detecting the position and the like when the distance between the detection means and the moving body is short.

  Further, according to the present invention, the electric field component generated by the estimated detection means directly from the ship is measured in time series by measuring the electric field generated by the ship navigating the sea surface or the sea as a moving object. And the value of the parameter satisfying the equation expressed by the sum of the electric field component based on the mirror image electrode virtually set with the seawater surface and the seafloor as the boundary, and at least the moving body based on the determined parameter value Since the current and / or future position is estimated and detected, it is possible to obtain a result closer to reality and accurately estimate and detect the position and the like.

  In addition, according to the present invention, when setting the mirror image electrode with the seawater surface and the seafloor as a boundary, a parameter relating to the electrical conductivity of the seabed is added, and the value is determined. Based on the determined value The direction of the moving body can be corrected with certainty.

  In addition, according to the present invention, the Gauss-Newton method is applied to the least square method, so that the least square method with good convergence stability is applied and the estimation of position and the like is quickly performed while reducing the calculation time. It can be performed with high accuracy.

  Furthermore, according to the present invention, it is possible to further estimate and detect the closest position (minimum distance) between the speed of the moving object and the reception position of a signal having a physical quantity of 2 or more based on the determined parameter value.

  Further, according to the present invention, the size of the physical quantity or the parameter value and the moving object corresponding to the physical quantity or the characteristics of the type are stored in a database, for example, so that the moving object is obtained based on the obtained signal and parameter value. Alternatively, the type can also be determined.

  Further, according to the present invention, the parameter value that satisfies the theoretical formula related to the point current source is obtained from the electric field data obtained by measuring the electric field generated by the moving body in the three-axis direction. Since at least the current and / or future position of the moving body is estimated and detected based on the determined parameter value, the position and the like can be accurately estimated and detected. This is particularly effective for estimating and detecting the position and the like when the distance between the detection means and the moving body is short.

  In addition, according to the present invention, the electric field generated by the moving sea surface or the ship navigating the sea is measured by the detection means in time series, and the estimated detection means is directly emitted from the ship from the digitized electric field data. A parameter value that satisfies the expression expressed by the sum of the electric field component and the electric field component based on the mirror image electrode virtually set with the seawater surface and the seabed as a boundary, and at least based on the determined parameter value Since the current and / or future position of the mobile object is estimated and detected, a result closer to reality can be obtained, and the position and the like can be estimated and detected accurately.

  Further, according to the present invention, the detection means further estimates and detects the closest position (minimum distance) between the speed of the moving object and the reception position of the signal of the physical quantity of 2 or more based on the determined parameter value. Thus, information other than the position can be further obtained.

  Further, according to the present invention, if the detection means stores, for example, a physical quantity size or parameter value and a moving object corresponding to the physical quantity or characteristics of the type in a database, based on the obtained signal and parameter value. More detailed information such as the moving object or its type can be obtained.

  In addition, according to the present invention, the parameter value satisfying the theoretical formula relating to the point current source is determined from the electric field data obtained by measuring the electric field generated by the moving body in time series in the three axis directions, Since the computer is caused to execute a program that estimates and detects at least the current and / or future position of the moving body based on the value, the position and the like can be accurately estimated and detected. This is particularly effective for estimating and detecting the position and the like when the distance between the detection means and the moving body is short.

  Further, according to the present invention, the electric field generated by the moving sea surface or a ship navigating in the sea is measured in time series, and the electric field component directly generated from the ship, the sea surface and the sea floor are obtained from the digitized electric field data. Determine a parameter value that satisfies the expression expressed by the sum of the electric field component based on the mirror-image electrode virtually set with the plane as a boundary, and at least the present and / or future of the moving object based on the determined parameter value Since the computer is caused to execute a program for estimating and detecting the position, it is possible to obtain a result closer to reality and accurately estimate and detect the position and the like.

  Further, according to the present invention, when setting the mirror image electrode with the seawater surface and the seafloor as a boundary, a parameter relating to the electrical conductivity of the seabed is added, and the value is determined by the computer. Based on this, the direction of the moving body can be corrected with certainty.

  In addition, according to the present invention, the computer is further made to detect and detect the closest approach position with respect to the receiving position of the velocity and physical quantity of the moving object based on the parameter values, so that information other than the position can be obtained. it can.

  In addition, according to the present invention, the program of the estimation detection method of the moving object position and the like has caused the computer to further determine the moving object or its type based on the magnitude of the physical quantity or the parameter value. More detailed information can be obtained.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing the configuration of a moving body position detection device according to the first embodiment of the present invention. In FIG. 1, an electric field detector (electric field sensor) 1 detects (receives) electric field intensity as a signal and converts it into an electric signal (hereinafter referred to as an electric field signal) (in some cases, based on other detected electric physical quantities). An electric signal whose electric field strength is calculated based on the signal may be used as an electric field signal, or may be converted into an electric signal after being converted into an optical signal). Here, the electric field detector 1 is a detector having three detection means orthogonal to each other or a detector representing a three-axis sensor, and can detect in the three-axis direction of an orthogonal (relative) coordinate system. . Actually, the electric field signal detected by the electric field detector 1 is not only the electric field generated by the moving body, but the electric field strength generated by the moving body is the strongest, so here the received electric field signal is caused by the moving body. It explains as being.

  The A / D converter 3 performs processing such as sampling, for example, and converts each electric field signal detected by the electric field detector 1 into a digital signal. The data collector 5 includes a data processing unit 5A and a data recording unit 5B. The data calculation unit 5A is a so-called database management system (DBMS) that performs a process of associating a triaxial electric field signal converted into a digital signal with a detected time. The data recording unit 5B is configured by a recording device, and records at least a certain time or a certain number of data, each of which includes an electric field signal (a component in three axes) and the detected time. This data collector 5 serves as a so-called database.

  The position etc. estimation detector 6 estimates and detects the position of the moving body based on the data (data representing physical quantity (electric field strength)) recorded in the data collector 5. Here, the position etc. estimation detector 6 is usually composed of control arithmetic processing means such as a computer centering on a CPU (Central Processing Unit). Then, the control calculation processing means executes a program that preliminarily calculates the estimation calculation processing procedure for the position, etc., and performs processing based on the program to perform calculation such as addition / subtraction / multiplication / division based on each formula described later, and further calculation Estimating the position or the like is realized by judging convergence or the like based on the result.

  Further, although not essential means in the apparatus of the present embodiment, the proximity detector 7 and the movement detector 8 are provided to judge the approach and movement of the moving body. For example, the data collector 5 starts recording the electric field signal. Alternatively, termination or the like can be controlled. In this embodiment, the depth meter 9 is provided in the vicinity of the electric field detector 1. Thereby, in the case of a ship in which the moving body travels on the water surface, for example, a depth (height) that is a distance in the Z-axis direction can be measured and used as a known value. ) Can be reduced.

  Here, hereinafter, in the case of a mobile body, the present embodiment will be described assuming a ship traveling in the sea. Therefore, it is assumed that the medium that conducts electricity is seawater (the electric field detector 1 detects the electric field strength in the sea as a signal). In addition, it is assumed that the moving body is performing a uniform linear motion. In order to align the coordinate axes, in order to make the XY plane of the coordinate system having the electric field detector 1 as the origin parallel to the sea surface, for example, a gimbal mechanism (not shown) is used so that the Z axis and the sea surface intersect perpendicularly. Should be installed. Further, for example, when the installation location cannot use the gimbal mechanism due to unevenness, an inclinometer (not shown) is provided, and based on the inclination data of the electric field detector 1 (detecting device such as moving body position) obtained from the inclinometer. Then, the position etc. estimation detector 6 may correct the axial direction and perform the calculation.

  FIG. 2 is a diagram illustrating the relationship between the position of the moving body and the electric field signal. Since seawater is an electrolyte solution, if different metals exist in seawater, a potential difference is generated. In this case, a current flows from a metal having a high ionization tendency to a metal having a low ionization tendency, and the anode surface is corroded. In a ship, for example, a hull outer plate is an anode (steel) and a propeller is a cathode (aluminum / copper), and a current is returned to the hull outer plate via a propeller main shaft to form a closed circuit. This current is the corrosion current. Moreover, in order to prevent metal corrosion due to such a corrosion current, an anticorrosion current may be passed. Therefore, for example, an anode electrode such as protective zinc or platinum for supplying current to seawater is provided on the hull. Moreover, the propeller, rudder, etc. which are provided in the stern part function as a cathode electrode for an electric current to flow in through seawater (inhale an electric current). And these become a current source (henceforth a point current source) with respect to the electric current which flows through seawater.

  If the distance between the electric field detector 1 and the moving body is long or the distance between the anode electrode and the cathode electrode is short, the point current source can be regarded as a dipole and a theoretical formula based on a dipole moment can be used. If this is not the case, the actual condition will deviate from the formula, and the parameter value determined based on the actual measurement value will deviate significantly from the true value, making it impossible to accurately detect the position of the moving object (actually the distance In some cases, the closer to is, the more accurate estimation and detection of the position is required). Therefore, in the present embodiment, calculation according to the point current source which is a monopole is performed, so that the position of the moving body can be accurately detected based on a formula in accordance with reality. The least squares method (especially the nonlinear least squares method is used for detecting the position and the like. Hereinafter, the least squares method is simply used. Specifically, the residual of the value obtained from the theory and the value obtained from the measured signal is used. The position is calculated based on the value of the parameter when it is determined that the predetermined convergence condition is satisfied, so that the sum of squares is minimized.

FIG. 3 is a diagram illustrating the relationship between the moving body and the point current source. When the moving body moves in the immediate vicinity of the electric field detector 1 by a uniform linear motion, the three-axis components (E _X , E _Y , E _Z ) of the electric field signal by the point current source provided on the moving body are expressed by the following equations: It is represented by (1) to (3).

E _X = ΣI _{σ i} · X _i / (X _i ² + Y _i ² + Z _i ² ) ^3/2 (1)
E _y = ΣI _{σ i} · Y _i / (X _i ² + Y _i ² + Z _i ² ) ^3/2 (2)
E _z = ΣI _{σ i} · Z _i / (X _i ² + Y _i ² + Z _i ² ) ^3/2 (3)

Here, the positions X ₁ and Y ₁ of the _first point current source from the reference position are
X ₁ = X ₀ + V cos α · t (4)
Y ₁ = Y ₀ + Vsin α · t (5)
age,
X _i = X ₁ + d _i · cos α · t (6)
Y _i = Y ₁ + d _i · sin α · t (7)
And

However,
X _0, Y _0: reference position i: number of points the current sources (1, 2, ...)
I σi: I _i / 4πσ ₁
I _i : Current amount of each point current source σ ₁ : Electrical conductivity of seawater (conductivity)
t: time V: moving body speed d _i : distance in the hull length direction between the first point current source and each point current source (1, 2,..., i−1)
Z _i : The height of the moving body from the electric field detector 1 (almost the same as the water depth for a ship traveling on water)
α: An angle formed by the X-axis direction of the electric field detector 1 and the moving direction of the moving body. Here, when the point current source I is viewed as a point charge Q, the point current source I and the point charge Q have a relationship of I = σ · Q / ε. ε is the dielectric constant. Also, ΣI _i = 0, that is, the sum of the point current sources is zero.

In the theoretical formula of the electric field obtained as described above, the parameter (unknown) determined for matching with the value based on the actually measured electric field signal is set as the following formula (7A) .
_{a e = (I σi, d} i, X 0, Y 0, Z i, V, α) ... (7A)

Based on the data recorded in the data collector 5, the position estimation detector 6 adjusts each parameter by the least square method so that the value based on the electric field actually detected by the electric field detector 1 satisfies the theoretical formula. Then, the parameter value is determined, and the position of the moving body is estimated and detected based on the determined value. When applying the method of least squares, an initial value is given to a parameter and calculation is performed. For example, with respect to the reference positions X ₀ and Y ₀ , X ₀ = 0 and Y ₀ = 0 (directly above the electric field detector 1) are set as initial values. Here, although X ₀ = 0 and Y ₀ = 0 are estimated values, they are values close to actual X ₀ and Y ₀ , so that a favorable calculation result can be obtained. Although there are various methods for the least square method, the Gauss-Newton method is applied in this embodiment. Here, it is assumed that the calculation is performed using the Levenberg-Marquardt method based on the Gauss-Newton method after considering the balance between the calculation time and convergence stability, the relationship with the function, etc. However, other solutions based on the Gauss-Newton method, such as the damping method and the Powell method, may be used. Further, instead of the Gauss-Newton method, other nonlinear least squares methods such as the steepest descent method may be used. When applied to electric field signals (electric field signal data), the following equations (7B) to (7D) are established.

^{_{P e t P e · Δa e}} = -P e t r e ... (7B)
^{_{P e t P e = P ex}} t P ex + P ey t P ey + P ez t P ez ... (7C)
^{_{P e t r e = P ex}} t r ex + P ey t r ey + P ez t r ez ... (7D)

However,
P _ex : Matrix consisting of the first derivative of each parameter of the electric field signal in the x-axis direction P _ey : Matrix consisting of the first derivative of each parameter of the electric field signal in the y-axis direction P _ez : Each parameter of the electric field signal in the z-axis direction A matrix consisting of first-order derivatives: r _e : sum of squares of residual Δa _e : a parameter correction value.

The position estimation detector 6 then continues until the sum of squares of the residual in the equation (7D) satisfies a predetermined convergence condition (for example, the sum of squares of the residual becomes a predetermined value or less, or the change rate of the sum of squares decreases. Iterative calculation is performed (until the value becomes a predetermined value or less). Here, until it is determined that the moving object is closest, it is calculated based on the latest data obtained by converting the actual magnetic field signal and electric field signal into digital signals (sampling and quantization). Are used as initial values of X ₀ and Y ₀ when the next iterative calculation is performed. Then, CPA (Closest Point of Approach: closest approach position (position at t = 0)) is estimated and detected based on the parameters (X ₀ , Y ₀ ) that satisfy the convergence condition. Furthermore, by substituting the determined values of the parameters V and α into the equations (4), (5) or (6) and (7), the current position of the moving body and the position of each point current source (stern etc.) Can be estimated and detected. Further, since the moving body is treated as having a constant velocity linear motion, a future position can also be predicted (estimated or detected) based on the estimated and detected current position and speed.

  For example, if data such as electrical physical quantities and parameter values generated from a moving object are associated with data of the moving object or its type, the data is obtained from the obtained electric field signal data and the determined parameter value. The body or its type can also be specified.

  As described above, according to the first embodiment, based on the electric field signals in the three-axis (orthogonal coordinate axes) directions detected by the electric field detector 1, the position etc. estimation detector 6 produces a result closer to reality. Using the theoretical formula of the electric field generated by the current flowing from the point current source of the ship, the least square method is applied to determine the parameter value so as to satisfy the value based on the electric field signal, and to the determined value Since the present position and / or future position of the moving body is estimated and detected based on the position, the position and the like can be estimated and detected accurately. This is particularly effective for estimating and detecting the position and the like when the distance between the electric field detector 1 and the moving object is short.

  In addition to estimating and detecting the current and / or future position of the mobile object, detailed data on the mobile object can be obtained by estimating and detecting the closest approach position and speed based on the determined parameter values. Can be estimated and obtained. For example, if data such as electric field strength and parameter values by a moving object is associated with the moving object or its type data, the moving object or its type can be determined from the obtained electric field signal data and the determined parameter value. Can also be specified. Furthermore, since the propeller or the like serves as a point current source, the position of the stern can be specified. Then, for example, if the bow position can be specified based on a signal such as a magnetic field, the hull length can be estimated, and the moving object or its type can also be specified.

  Furthermore, since the Gauss-Newton method, particularly the Levenberg-Marquardt method or the modified Marquardt method, is used as the solution of the least square method, the least square method with good convergence stability is applied while reducing the calculation time. The position and the like can be detected quickly and with high accuracy.

Embodiment 2. FIG.
FIG. 4 is a diagram showing a mirror image point current source (mirror image electrode) for a point current source (electrode) in the hull. It is conceivable that the electric field generated in the sea water (which becomes an electric field signal) is most affected by the atmosphere and the boundary between the sea floor (sea water surface and sea bottom) having a different dielectric constant (electrical conductivity) from sea water. Therefore, using the mirror image theory, the mirror image point current source for the point current source in the hull is virtually assumed to be the electric field (electric field signal) generated in the seawater (the hull wall, seawater temperature) However, it is difficult to consider all the influences, and the influence is negligible, so it is omitted here).

  Here, mirror image theory means that, for example, when two different dielectric media (seawater and air, seawater and seabed) are in contact with each other at the interface (seawater surface, seafloor), the charge (dots) in one medium A method for obtaining an electric field by virtually providing an electric charge (point current source, electrode) in another medium having no electric charge, instead of directly solving an electric field generated by a current source or an electrode in consideration of boundary conditions. It is. In this case, the electric field can be obtained without disturbing the boundary condition.

  In the present embodiment, a mirror image point current source is virtually provided (placed) to calculate the theoretical value of the electric field, thereby reducing the deviation from the actual measurement value, and performing more accurate position detection and the like. Although the process of the position etc. estimation detector 6 is different, the configuration is the same as that of the moving body position detection apparatus of the first embodiment, so this embodiment will also be described with reference to FIG.

In this embodiment, (a) For each point current source A in the hull,
(B) A mirror image point current source (hereinafter referred to as mirror image point current source B) that is paired with the point current source of (a) across the sea floor.
(C) Mirror image point current source that is paired with the point current source of (a) across the seawater surface (hereinafter referred to as mirror image point current source C)
(D) A mirror image point current source (hereinafter referred to as a mirror image point current source D) paired with the mirror image point current source of (b) across the sea floor.
These three mirror image point current sources are virtually placed and the electric field relating to each point current source is calculated. Although a mirror image point current source based on other conditions is also conceivable, it is omitted here because it is negligibly small (the mirror image point current source D may be ignored in some cases).

Assuming that the current value at the point current source (electrode) provided on the hull is I _A (I _i in the first embodiment), the current value I _B of the virtual point current source is expressed by the following equation (8). . Similarly, the current value I _C current value I _D is expressed by the following equations (9) and (10). Here, in this embodiment, each component of the electric field represented by (1) to (3) described in the first embodiment is expressed as (E _Ax , E _Ay , E _Az ).
I _B = (σ ₁ −σ ₂ ) I _A / (σ ₁ + σ ₂ ) (8)
I _C = (σ ₁ −σ ₃ ) I _A / (σ ₁ + σ ₃ ) (9)
I _D = (σ ₁ −σ ₂ ) I _A / (σ ₁ + σ ₂ ) (10)

When considered based on the equations (8) to (10), the electric field generated by the mirror image point current source B is represented by the following equations (11) to (13).
E _Bx = {(σ ₁ −σ ₂ ) I _σi / (σ ₁ + σ ₂ ) } ・ X _i
/ {X _i ² + Y _i ² + (− Z _i ) ² } ^3/2 (11)
E _By = {(σ ₁ −σ ₂ ) I σ _i / (σ ₁ + σ ₂ )} · Y _i
/ {X _i ² + Y _i ² + (− Z _i ) ² } ^3/2 (12)
_{E BZ = {(σ 1 -σ} 2) I σi / (σ 1 + σ 2)} · (-Z i)
/ {X _i ² + Y _i ² + (− Z _i ) ² } ^3/2 (13)

Similarly, the electric field generated by the mirror image point current source C is expressed by the following equations (14) to (16).
E _Cx = {(σ ₁ −σ ₃ ) I σ _i / (σ ₁ + σ ₃ )} · X _i
/ {X _i ² + Y _i ² + (2Zs−Z _i ) ² } ^3/2 (14)
E _Cy = {(σ ₁ −σ ₃ ) I σ _i / (σ ₁ + σ ₃ )} · Y _i
/ {X _i ² + Y _i ² + (2Zs−Z _i ) ² } ^3/2 (15)
E _CZ = {(σ ₁ −σ ₃ ) I σ _i / (σ 1 + σ ₃ )} · (2Zs−Z _i )
/ {X _i ² + Y _i ² + (2Zs−Z _i ) ² } ^3/2 (16)

Further, the electric field generated by the mirror image point current source D is expressed by the following equations (17) to (19).
E _Dx = {(σ ₁ −σ ₂ ) I _σi / (σ ₁ + σ ₂ )} · X _i
/ {X _i ² + Y _i ² + (Z _i −2Zs) ² } ^3/2 (17)
E _Dy = {(σ ₁ −σ ₂ ) I σ _i / (σ ₁ + σ ₂ )} · Y _i
/ {X _i ² + Y _i ² + (Z _i −2Zs) ² } ^3/2 (18)
E _DZ = {(σ ₁ −σ ₂ ) I σ _i / (σ ₁ + σ ₂ )} · (Z _i −2Zs)
/ {X _i ² + Y _i ² + (Z _i −2Zs) ² } ^3/2 (19)

here,
σ ₁ : Electrical conductivity of seawater σ ₂ : Electrical conductivity of seabed σ ₃ : Electrical conductivity of air (= 0)
Zs: water depth.

The electric field (E _x , E _y , E _z ) is finally expressed by the sum of the point current sources (point current sources) as in the following equations (20) to (22), for example. Become. Here, depending on the environmental conditions and the like, it may be realistic not to consider all the mirror image point current sources, and the amount of calculation increases when all terms are added, so (20) to (22). In the formula, one or more terms may be omitted.
E _x = E _Ax + E _Bx + E _Cx + E _Dx (20)
E _y = E _Ay + E _By + E _Cy + E _Dy (21)
E _y = E _Az + E _Bz + E _Cz + E _Dz (22)

Based on (E _x , E _y , E _z ) calculated as described above, the parameter value is calculated and determined by the method of least squares, as in the first embodiment. Here, in the present embodiment, in addition to the parameters shown in the equation (8), for example, parameters including electrical conductivity σ ₂ of the seabed such as σ ₂ , σ ₁ −σ ₂ , σ ₁ + σ _2, etc. Is added. Here, in particular, σ ^* (conductivity ratio) where σ ^* = (σ ₁ −σ ₂ ) / (σ ₁ + σ ₂ ) is added as a parameter. Therefore, parameters for performing position estimation and the like are set as in the following equation (23).
_{a e = (I σi, d} i, X 0, Y 0, Z i, V, α, σ *) ... (23)

Here, it is verified whether there is a combination of similar parameters in the equations (20) to (22). The electric field signal forms a signal waveform by combining values of a plurality of parameters such as position and velocity. Similarity refers to the case where there are innumerable combinations of values even with the same electric field signal waveform. At this time, parameters such as position and speed estimated from the signal are not uniquely determined and become indefinite. Similar parameters are parameters determined by k and k ′ satisfying the equations (20) to (22) except for k = 1 and k ′ = 1 in the following equation (24). If there are similar parameters, k and k 'can take any value, so there are an infinite number of combinations, and the values of parameters such as moving body speed and initial position are determined as one set. It will not be possible.
a _e = (k′I σ _i , d _i , kX ₀ , kY ₀ , kZ _i , kV, α, σ ^* ) (24)

  Then, consider the identity of equations (20) to (22) based on the parameters of equation (23) and equations (20) to (22) based on the parameters of equation (24). The values of k and k ′ satisfying this identity are at most finite. Among these values, even if they exist mathematically, there are only k = 1 and k ′ = 1 that can be taken at least within the range of a realistic moving body (especially a ship). (This is the same even if the first or second term is omitted from the second to fourth terms in the equations (20) to (22).) Therefore, the moving object is derived from the equations (20) to (22). The parameters such as the speed and the initial position can be determined as one set. Thereby, the speed, position, etc. of the ship navigating on the water and the moving body in the sea can be estimated.

Here, in the determined parameter value, σ ^* > 1 may be satisfied. In this case, a value obtained by performing the following correction on the determined parameter value is newly determined as the parameter value. When σ ^* > 1, the moving direction of the moving body is reversed (the direction relation of the point current source is also reversed in accordance with the direction).
I _σi after correction: −I _σi (before correction) × σ ^* (before correction)
Α after correction: α (before correction) −180 ° σ ^* after correction: 1 / σ ^* (before correction)

FIG. 5 is a diagram showing the relationship between the true direct distance and the estimated direct distance in consideration of the mirror image electrode. Here, in order to verify the presence or absence of a similar parameter, the estimated direct distance is calculated using Z _i as a parameter. FIG. 5A shows a case where the moving body (ship) speed V is 3 m / s, and FIG. 5B shows a case where the moving body speed is 6 m / s. In addition, as other conditions, CPA (Closest Point of Approach) is 20 m, water depth Zs is 100 m, and the moving body has one anode electrode and one cathode electrode. ing. The cathode electrodes (stern) are X ₁ and Y ₁ .

In FIG. 5, a result is obtained in which the estimated linear distance and the true linear distance substantially coincide. Thereby, it can be confirmed that there is no similar parameter when the mirror image point current source (electrode) is considered. Accordingly, the reference positions X ₀ and Y ₀ , the moving body speed V, and the height Z _i of the moving body from the electric field detector 1 can be uniquely determined. Here, in order to simplify the model, the result is shown for a moving body in which one anode electrode and one cathode electrode are provided. For example, even if a plurality of anode electrodes (cathode electrodes) are provided, the moving body Within the range of values that can actually be taken as measurement results, there are at least no similar parameters (no k or k ′ such as such values exist), and a unique, highly accurate estimation of position, etc. Detection can be performed.

  As described above, according to the second embodiment, in consideration of boundary conditions on the sea surface and the sea bottom, a virtual mirror image point current source (electrode) is provided, and the electric field from the point current source on the ship is The equation is set as the electric field generated by the ship with the sum of the electric field generated by the mirror image point current source (electrode) and the position estimation detector 6 applies the least square method to satisfy the value based on the electric field signal. Since the value is uniquely determined and the current and / or future position of the moving body moving on the sea surface and the sea is estimated and detected based on the determined value, the result is more realistic and accurate. The position and the like can be estimated and detected. For ships navigating the surface of the sea, the depth of the point current source, such as screw, rudder, etc., changes depending on the size (weight) of the ship (basically, the heavier it is, the deeper the position from the sea surface). Based on the parameter of the height of the point current source (distance in the Z-axis direction with respect to the electric field detector 1), the size (weight) of the ship can be estimated.

Embodiment 3 FIG.
In the first embodiment described above, a description has been given assuming that a plurality of point current sources (electrodes) are arranged in a line in the hull length direction. Here, for example, consider a case where a plurality of point current sources (particularly anode point current sources) are considered in a ship arranged in two rows of port and starboard (in the width direction of the ship). In this case, not only d _i which is a parameter in the hull length direction but also the next parameter d _wi is added. As a result, the theoretical formula can be made closer to the actual one, and the position and the like can be accurately estimated and detected.
d _wi : Spacing in the width direction of each point current source

Embodiment 4 FIG.
In the second embodiment described above, the mirror image theory is applied to the theory based on the point current source and the theoretical formula is set. However, the present invention is not limited to this. For example, in the theory based on the dipole moment, as described in the second embodiment by applying the mirror image theory, the theoretical formula is obtained by using the sum of the electric field formulas of the mirror point current sources from the dielectric constant of each medium. Can be set. Also, in the case of detecting the magnetism as a signal and estimating and detecting the position or the like, the mirror image theory can be applied between media having different magnetic permeability to the theoretical formula for use in the method of least squares.

1 is a configuration block diagram of a moving body position detection device according to a first embodiment of the present invention. It is a figure showing the relationship between the position of a moving body and an electric field signal. It is a figure showing the relationship between a mobile body and a point current source. It is a figure showing the mirror image point current source (electrode) with respect to the point current source in a ship body. It is a figure showing the relationship between a true direct distance and the estimated direct distance which considered the mirror-image electrode.

Explanation of symbols

  1 electric field detector, 3 A / D converter, 5 data collector, 5A data processing unit, 5B data recording unit, 6 position estimation detector, 7 proximity detector, 8 movement detector, 9 depth meter

Claims (16)

Measure the electric field generated by the moving object in time series, and from the digitized electric field data,
The estimation detection means applies a least square method using a residual to determine a parameter value such that the value of the electric field data satisfies the theoretical formula relating to the point current source, and based on the determined value of the parameter And at least a current position and / or a future position of the moving body is estimated and detected. A step of digitizing a signal of an electric field generated by a moving body, which is received for each component in three axial directions by the detection means, and collecting the data as data in time series;
Applying a least square method using a residual to the collected data, and determining a parameter value so that the value of the data satisfies a theoretical formula relating to a point current source;
A method of estimating and detecting a moving object position and the like, comprising: estimating and detecting at least a current and / or future position of the moving object based on the determined parameter value. Measure the electric field generated by a moving sea surface or a ship navigating in the sea in time series. From the digitized electric field data,
The estimation detection means determines a parameter value that satisfies an expression represented by a sum of an electric field component directly emitted from the ship and an electric field component based on a mirror image electrode virtually set with the sea surface and the sea bottom as a boundary. A method for estimating and detecting a moving body position and the like, wherein at least a current and / or future position of the moving body is estimated and detected based on the determined value of the parameter.   4. The method for estimating and detecting the position of a moving body according to claim 3, wherein values are further determined for parameters including electrical conductivity of seawater and the seabed. The method for estimating and detecting the position of a moving body according to claim 1 or 2, wherein a Gauss-Newton method is applied to the least square method.   The method for estimating and detecting the position of a moving body according to claim 1, further comprising estimating and detecting a position closest to the speed of the moving body and a reception position of the signal of the electric field.   The method for estimating and detecting a moving object position or the like according to claim 1, wherein the moving object or the type thereof is determined based on the intensity of the electric field or the value of the parameter. Detecting means for detecting an electric field by each component in three axial directions;
Data recording means for recording the signal detected by the detecting means in time series as electric field data;
The parameter value is determined by iterative calculation using the least squares method using the residual until a predetermined convergence condition is satisfied so that the value of the electric field data satisfies the theoretical formula of the electric field related to the point current source. And a detecting means for estimating and detecting the position of the moving body based on the determined value of the parameter, and detecting means for estimating and detecting at least a current and / or future position of the moving body. Detecting means for detecting an electric field by each component in three axial directions;
Data recording means for recording the signal detected by the detecting means in time series as electric field data;
The data value of the data recording the field stored in the means, the mirror image electrode set virtually the sea or directly the emitted electric field component and sea level from ships sailing the sea and the seafloor is a mobile as a boundary A parameter value satisfying the expression expressed by the sum of the electric field component based on the value is determined by applying a least square method using a residual, and at least the current and current values of the moving object are determined based on the determined parameter value. And / or a detection means for estimating and detecting a future position.   10. The moving object position estimation detecting device according to claim 8 or 9, wherein the detecting means further estimates and detects a speed of the moving object and a closest approach position to the detecting means based on the parameter value. . 10. The apparatus according to claim 8, wherein the detecting unit determines the moving body or the type thereof based on the intensity of the electric field or the value of the parameter. The detection means digitizes the signal of the electric field generated by the moving body received for each component in the three-axis directions, applies a least square method using a residual to the data collected in time series as data, Determining the value of the parameter so that the value satisfies the theoretical formula for the point current source;
A program for an estimated detection method for a moving object position, for example, which causes a computer to perform at least a step of estimating and detecting a current and / or future position of the moving object based on the determined parameter value. The electric field generated by a moving sea surface or a ship navigating in the sea is measured in time series. Determining a value of a parameter that satisfies an expression represented by a sum of electric field components based on a set mirror image electrode;
A computer program for estimating and detecting a moving object position and the like, which causes a computer to perform at least a step of estimating and detecting a current and / or future position of the moving object based on the determined value of the parameter. 14. The program according to claim 13, wherein the computer further determines values of parameters including seawater and seabed electrical conductivity.   15. The computer according to claim 12, further causing the computer to perform estimation and detection of the closest position to the speed of the moving body and the reception position of the electric field signal based on the parameter value. A program for a method for detecting and detecting the position of a moving object. The mobile object position estimation detection method according to any one of claims 12 to 14, wherein the computer further makes a determination of the mobile object or its type based on the intensity of the electric field or the value of the parameter. program.

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