CN105180943B - Ship-positioning system and method - Google Patents

Abstract

The invention discloses a kind of ship-positioning system, including: location information acquiring unit, for obtaining multiple positional informationes of boats and ships from multiple different positioning ends；Sequencing unit, for being ranked up the multiple positional informationes got according to priority, sends priority to integrated unit more than the multiple positional informationes setting threshold value；Integrated unit, merges priority more than the multiple positional informationes setting threshold value, draws unique boats and ships latitude and longitude coordinates；Monitoring unit, for obtaining ship monitor image according to boats and ships latitude and longitude coordinates.The present invention can realize being accurately positioned of boats and ships.

Description

Ship positioning system and method

Technical Field

The invention belongs to the field of traffic, and particularly relates to a ship positioning system and method.

Background

At present, many identity recognition systems are installed in maritime affairs for ships on inland waterway, such as ship-borne Automatic Identification System (AIS), Radio Frequency Identification (RFID), inter-site test signals (VITS), satellite positioning, radar, etc. Each system has a longitude and latitude position, which results in that the background system cannot judge which longitude and latitude position is accurate. In addition, since these systems exist alone, they cannot be linked to a closed circuit television camera (CCTV), which may result in the failure of the maritime department to confirm the identity of the ship by viewing the CCTV video. CCTV and positioning system are separated in current maritime affairs system, or can only look over the real-time video of boats and ships through CCTV, or can only look over the position of boats and ships on the map through positioning system, and this kind of mode has a very big shortcoming, and maritime affairs personnel can't pass through CCTV alone or the information of AIS accurate positioning boats and ships.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a ship positioning system and a ship positioning method.

A vessel locating system comprising: the positioning device comprises a position information acquisition unit, a positioning unit and a positioning unit, wherein the position information acquisition unit is used for acquiring a plurality of position information of a ship from a plurality of different positioning ends; the sorting unit is used for sorting the acquired position information according to priority and sending the position information with the priority greater than a set threshold value to the fusion unit; the fusion unit is used for fusing a plurality of position information with the priority level larger than a set threshold value to obtain a unique ship longitude and latitude coordinate; and the monitoring unit is used for acquiring a ship monitoring image according to the longitude and latitude coordinates of the ship.

Optionally, the position information includes the current longitude and latitude of the ship, the time of acquiring the position information, and the identifier of the positioning end.

Optionally, the sorting the acquired position information according to priority includes: subtracting the current time from the time of the ship position information acquired by each positioning end to obtain the time length of the position information sent by each positioning end from the current time, and sequencing the position information according to the priority sequence of the time lengths from small to large.

Optionally, the plurality of different positioning ends include: AIS, RFID, VITS, satellite positioning, and/or radar.

Optionally, the fusing the position information with the priority greater than the set threshold to obtain the unique ship longitude and latitude coordinate specifically includes: at the current moment t, the real position of the ship at the moment is set as P^tBefore time t, the position coordinates in the position information with the priority greater than the set threshold are Let A, V, G be the three coordinates corresponding to three points respectively, and the vector velocity beAnd are respectively distant from time tCalculating the reference position of the ship at the time t according to the coordinates and the vector speedWherein:

and (B) point A:

point V:

and point G:

using the earth as a reference system, calculating A, V, G reference center and earth coordinates corresponding to the three points as (B)_A，L_A，H_A)、(B_V，L_V，H_V)、(B_G，L_G，H_G) The coordinate system takes the center of a reference ellipsoid as a coordinate origin, and the short axis of the ellipsoid is superposed with the rotating axis of the reference ellipsoid; b is the geodetic latitude, which is the included angle between the normal of the ellipsoid passing through the ground point and the equatorial plane of the ellipsoid; l is the geodetic longitude, such thatAn included angle between the ellipsoid meridian plane passing through the ground point and the initial meridian plane; h is the height of the ground;

converting geodetic coordinates into space rectangular coordinates, wherein the conversion formula is as follows:

in a space rectangular coordinate system, 1) taking a reference center O as a coordinate origin; 2) the Z axis coincides with the short axis of the reference ellipsoid; 3) the X axis is superposed with the intersection line of the initial meridian plane and the equator; 4) the Y axis is vertical to the X axis on the equatorial plane to form a right-hand rectangular coordinate system O-XYZ; in the formula (4), N is the curvature radius of the ellipsoidal unitary-ground ring, e is the first eccentricity of the ellipsoid, the long and short radii of the ellipsoids a and b, and W is the first auxiliary coefficient; wherein: a is 6378.137 km; b is 6356.7523141 km;

$N=\frac{a}{W}---\left(5\right)$

the coordinates of the A, V, G points are substituted into the formulas (5) - (7), and the spatial rectangular coordinates corresponding to A, V, G are calculated to be (X)_A，Y_A，Z_A)、(X_V，Y_V，Z_V)、(X_G，Y_G，Z_G) (ii) a Fusing A, V, G points into one point, making the point be the S point, the algorithm is as follows:

$\left\{\begin{array}{c}{X}_s=\frac{X_A+X_V+X_G}{3}\\ Y_s=\frac{Y_A+Y_V+Y_G}{3}\\ Z_s=\frac{Z_A+Z_V+Z_G}{3}\end{array}\right.---\left(8\right)$

the coordinate of the S point is obtained as (X)_S，Y_S，Z_S) (ii) a In order to obtain longitude and latitude coordinates, the space rectangular coordinates are converted into geodetic coordinates, and the conversion formula is as follows:

after the processing of the fusion unit, the unique longitude and latitude coordinate S point is obtained as (B)_S，L_S，H_S)。

Optionally, the method for obtaining a ship monitoring image according to a ship longitude and latitude coordinate specifically includes: setting the obtained longitude and latitude coordinates of the ship as an S point, and obtaining the horizontal distance a between the camera and the S point₁Distance b between camera and ground₁As is known, according to the right-angled triangle pythagorean theorem:

$c=\sqrt{{a_1}^2+{b_1}^2}---\left(10\right)$

the distance c between the camera and the point S is obtained, so that the focal length of the camera is adjusted, and according to the right-angle surface, the depression angle alpha of the camera can be determined to be:

$\mathrm{\α}=\arcsin \frac{a_1}{c}---\left(11\right)$

then, the true azimuth angle of the point S relative to the camera is calculated, namely, the horizontal included angle between the line from the true north direction line of a certain point to the target direction line along the clockwise direction is calculated, and the true azimuth angle is calculated by adopting a station-centered horizontal coordinate system; assuming that the position of the camera is M point, the geodetic coordinate of the point is (B)_M，L_M，H_M) Converted into spatial rectangular coordinates, i.e. (X), by the coordinate conversion formula (4) described above_M，Y_M，Z_M) Taking a coordinate system where the M point is located as a station center rectangular coordinate system and recording as M-NEU, knowing spatial rectangular coordinates of the M point and the S point, and obtaining the following results according to the translation and rotation relationship between the two coordinate systems:

wherein,

$R_1=\left[\begin{array}{ccc}1& 0& 0\\ 0& -1& 0\\ 0& 0& 1\end{array}\right]---\left(16\right)$

thus, the coordinates (N, E, U) of point S in the station-centric horizontal coordinate system at point M are found:

$\left[\begin{array}{c}N\\ E\\ U\end{array}\right]=\left[\begin{array}{ccc}-{\mathrm{sinB}}_M{\mathrm{cosL}}_M& -{\mathrm{sinL}}_M{\mathrm{sinB}}_M& {\mathrm{cosB}}_M\\ -{\mathrm{sinL}}_M& {\mathrm{cosL}}_M& 0\\ {\mathrm{cosB}}_M{\mathrm{cosL}}_M& {\mathrm{cosB}}_M{\mathrm{sinL}}_M& {\mathrm{sinB}}_M\end{array}\right]*\left[\begin{array}{c}{X}_S-X_M\\ Y_S-Y_M\\ Z_S-Z_M\end{array}\right]---\left(17\right)$

the azimuth angle from point M to point S is: theta as arctan (E/N) (18)

And adjusting the position of the camera according to the true azimuth angle theta.

A method of locating a vessel, comprising the steps of: s100: acquiring a plurality of position information of a ship from a plurality of different positioning ends; s200: sequencing the acquired position information according to priority, and sending the position information with the priority greater than a set threshold to a fusion unit; s300: fusing a plurality of position information with the priority greater than a set threshold value to obtain a unique ship longitude and latitude coordinate; s400: and acquiring a ship monitoring image according to the longitude and latitude coordinates of the ship.

Optionally, the position information includes the current longitude and latitude of the ship, the time of acquiring the position information, and the identifier of the positioning end.

Optionally, step S200 specifically includes: subtracting the current time from the time of the ship position information acquired by each positioning end to obtain the time length of the position information sent by each positioning end from the current time, and sequencing the position information according to the priority sequence of the time lengths from small to large.

Optionally, the plurality of different positioning ends include: AIS, RFID, VITS, satellite positioning, and/or radar.

The invention has the beneficial effects that: according to the invention, the longitude and the latitude are obtained through the fusion algorithm of the longitude and latitude positions and then linked with the monitoring system, so that maritime personnel can accurately know the relevant information of the ship in the video, and the ship can be accurately positioned for video monitoring.

Drawings

FIG. 1 is a schematic diagram of the configuration of the vessel positioning system of the present invention;

FIG. 2 is a spatial geodetic coordinate system;

FIG. 3 is a rectangular spatial coordinate system;

FIG. 4 is a schematic diagram of the monitoring unit linked with the point S;

FIG. 5 is a schematic diagram of a isocenter rectangular coordinate system and a spatial rectangular coordinate system;

fig. 6 is a flow chart of the vessel positioning method of the present invention.

Detailed Description

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings. Like reference numerals refer to like parts throughout the drawings. The drawings are not intended to be to scale, emphasis instead being placed upon illustrating the principles of the invention.

Example 1

As shown in fig. 1, the ship positioning system of the present invention includes a position information acquiring unit, a sorting unit, a fusion unit, and a monitoring unit, which are connected in sequence. The system firstly collects ship position information uploaded by all positioning ends through a position information acquisition unit, and then a unique longitude and latitude information is obtained through judgment and calculation of a sorting unit and a fusion unit through related rules and is used for accurately representing the geographical position of a ship. The system sends the accurate geographic position to the monitoring unit, and the monitoring unit combines the uploaded geographic position according to the ship image in the video range thereof, and can design a floating window above the ship in the video for displaying the relevant information of the ship.

A position information acquiring unit for acquiring a plurality of position information of the ship from different positioning terminals, generally speaking, a plurality of positioning terminals are installed on the ship, such as a first positioning terminal (which may be AIS), a second positioning terminal (which may be RFID), a third positioning terminal (VITS), a fourth positioning terminal (which may be GPS), a fifth positioning terminal (which may be radar), etc., the position information acquiring unit receives ship position information transmitted by various positioning terminals, the ship position information may include the latitude and longitude of the current position of the ship, the time of acquiring the position information, and the positioning end identifier, etc., and it should be noted that the positioning end identifier in the present invention refers to an identifier indicating which positioning end the position information is acquired from, for example, for the fourth positioning end, the fourth positioning end obtains the position information (.t_GGPS) is: (31.203181, 121.505543), 20150910153008, GPS; the piece of information shows that the ship is currently at the north latitude N31 degrees 20 '31.81' east longitude E121 degrees 50 '55.43', the acquisition time of the position information is 2015, 9, 10, 15, 30 min and 08 sec, the position information is acquired from a GPS positioning end, the GPS in the information is a positioning mark, P_GRepresenting the position coordinates of the vessel. Different location terminals have different location identifications, for example, the location identification of AIS may be AIS, and the location identification of RFID may be RFID, etc.

The position information acquisition unit sends the acquired position information to the sequencing unit, and the sequencing unit is mainly used for sequencing the acquired position information according to the priority and sending the position information with the priority greater than a set threshold to the fusion unit. Specifically, the position information acquiring unit may acquire the position information sent by different positioning terminals at different times, in order to ensure that the ship obtained by the subsequent fusion algorithmThe accuracy of the ship position needs to sort the position information, the priority sorting is carried out according to the acquisition time of the positioning information, and the positioning information with the later priority is discarded after the sorting, so that the positioning information used by the fusion algorithm is the latest positioning information, and the positioning accuracy is improved. For example, before the current time t, the last position information provided by the first positioning end, the second positioning end, the third positioning end and the fourth positioning end is: (t_A、AIS)、(t_R、RFID)、(t_V、VITS)、(t_GGPS), whereinRespectively representing the position coordinates t of the ship obtained by the first positioning end, the second positioning end, the third positioning end and the fourth positioning end_A、t_R、t_V、t_GThe time of the ship position information acquired by the first positioning end, the second positioning end, the third positioning end and the fourth positioning end is respectively represented, and the AIS, the RFID, the VITS and the GPS respectively represent positioning marks of the first positioning end, the second positioning end, the third positioning end and the fourth positioning end. After the position information is obtained, the sequencing unit firstly reads the positioning identification in the information so as to determine which positioning end the position information comes from, and then the sequencing unit subtracts the time of the obtained ship position information from the current time t so as to obtain the time length of the position information sent by different positioning ends from the current time t, namely the time lengthIn the formulaRespectively showing the time length of the position information sent by the first positioning end, the second positioning end, the third positioning end and the fourth positioning end from the current moment. After acquiring the time lengths of the position information sent by different positioning ends from the current time t, the sorting unit compares the time lengths, and sorts the time lengths in a descending order, for example, the sorting result is as follows:this means that the positioning information obtained from the first positioning end has the shortest time length from the current time t, and the positioning information obtained from the fourth positioning end has the longest time length from the current time t. The sequencing unit sequences the acquired position information according to the priority, and the sequencing result is as follows: the first positioning end is larger than the third positioning end and larger than the fourth positioning end and larger than the second positioning end, if the first positioning end, the second positioning end, the third positioning end and the fourth positioning end respectively represent AIS, RFID, VITS and GPS, the priority of the position information obtained from the four positioning ends is as follows: AIS > VITS > GPS > RFID. That is, the priorities of the four systems are 1, 2, 3, and 4, respectively, and if the threshold set by the system is 2, the sorting unit sends the position information acquired from the first positioning terminal and the third positioning terminal to the merging unit, and if the threshold set by the system is 3, the sorting unit sends the position information acquired from the first positioning terminal, the third positioning terminal, and the fourth positioning terminal to the merging unit.

And the fusion unit is used for receiving the position information with the priority level larger than the set threshold value sent by the sorting unit and fusing the position information with the priority level larger than the set threshold value to obtain the unique ship longitude and latitude coordinates. Specifically, the sorting unit sends the position information obtained from the first positioning end, the third positioning end, and the fourth positioning end to the fusion unit. According to the sequence, a first positioning terminal, a third positioning terminal and a fourth positioning terminal (AI) are obtainedS, VITS, satellite positioning) are provided as position coordinates P_A、P_V、P_G. At a specific time t, the real position of the ship is set as P^t. Before time t, the AIS, VITS and satellite positioning provide the last position coordinates respectivelyLet A, V, G be the three coordinates corresponding to the three points, respectively. Vector velocity ofAnd are respectively distant from time tAccording to the coordinates and the vector speed, the reference position of the ship at the time t can be calculatedWherein:

and (B) point A:

point V:

and point G:

as shown in FIG. 2, using the earth as a reference system, the coordinates of the center of gravity corresponding to A, V, G are obtained from the reference position as (B)_A，L_A，H_A)、(B_V，L_V，H_V)、(B_G，L_G，H_G) The coordinate system takes the center of a reference ellipsoid as a coordinate origin, and the short axis of the ellipsoid is superposed with the rotating axis of the reference ellipsoid; b is the latitude of the earth, which is an ellipse passing through the ground pointThe included angle between the normal line of the sphere and the equatorial plane of the ellipsoid; l is the earth longitude, and is the included angle between the ellipsoid meridian plane passing through the ground point and the initial meridian plane; h is the geodetic height, and since the coordinates of the longitude and latitude of each point and the distance between each point are nonlinearly transformed, in order to obtain a unique longitude and latitude, the geodetic coordinates are converted into spatial rectangular coordinates, and the conversion formula is as follows:

as shown in fig. 3, in the rectangular spatial coordinate system, 1) the reference center O is used as the origin of coordinates; 2) the Z axis coincides with the minor axis (rotation axis) of the reference ellipsoid; 3) the X axis is superposed with the intersection line of the initial meridian plane and the equator; 4) the Y axis is vertical to the X axis on the equatorial plane to form a right-hand rectangular coordinate system O-XYZ; in the formula, N is the curvature radius of the ellipsoidal unitary-ground ring, e is the first eccentricity of an ellipsoid, the long and short radii of the ellipsoids a and b, and W is a first auxiliary coefficient; wherein: a is 6378.137 km; b is 6356.7523141 km;

$N=\frac{a}{W}---\left(5\right)$

the coordinates of A, V, G are substituted into the above formula to obtain A, V, G corresponding spatial rectangular coordinates (XA, YA, ZA), (XV, YV, ZV), (XG, YG, ZG), in order to obtain more accurate position information of the ship, A, V, G three points are merged into one point, which is the S point, here, the invention adopts the following algorithm:

$\left\{\begin{array}{c}{X}_s=\frac{X_A+X_V+X_G}{3}\\ Y_s=\frac{Y_A+Y_V+Y_G}{3}\\ Z_s=\frac{Z_A+Z_V+Z_G}{3}\end{array}\right.---\left(8\right)$

from this, the coordinate of the S point is (X)_S，Y_S，Z_S) (ii) a In order to obtain longitude and latitude coordinates, the spatial rectangular coordinates are also converted into geodetic coordinates, and the conversion formula is as follows:

after the processing of the fusion unit, the unique longitude and latitude coordinate S point (B) can be obtained_S，L_S，H_S). The algorithm effectively improves the accuracy of ship positioning.

After the longitude and latitude coordinates S point of the ship is obtained, the fusion unit sends the coordinates to the monitoring unit, the monitoring unit can be linked with the longitude and latitude coordinates of the ship, for example, the monitoring unit can open a monitoring probe of the longitude and latitude coordinate accessory, the ship is subjected to image capture through the monitoring probe, a video monitoring image of the ship can be obtained, a floating window can be arranged in a monitoring screen and used for displaying the ship image captured in real time, and the rest part of the screen can display the current position of the ship through a map, so that the linkage of the video monitoring and positioning end can be realized.

In order to make the monitoring probe catch the ship, as shown in fig. 4, after the position information of the S point is obtained, the horizontal distance a between the camera and the S point can be obtained₁Distance b between camera and ground₁As is known, according to the right-angled triangle pythagorean theorem:

$c=\sqrt{{a_1}^2+{b_1}^2}---\left(10\right)$

the distance c between the camera and the S point can be obtained, so that the CCTV can adjust the focal length of the camera according to the position information. According to the right-angle surface, the depression angle alpha of the camera can be determined as follows:

$\mathrm{\α}=\arcsin \frac{a_1}{c}---\left(11\right)$

for better positioning of the camera, the true Azimuth (Azimuth) of the point S relative to the camera, i.e. the horizontal angle from the true north line to the target line in the clockwise direction from the point, is also determined.

In order to obtain the true azimuth, the patent adopts a station center horizontal coordinate system to calculate the true azimuth. Setting the position of the camera as M point, the earth of the point is seatedIs marked as (B)_M，L_M，H_M) Converted into space rectangular coordinates, i.e. (X), by the coordinate conversion formula_M，Y_M，Z_M). As shown in fig. 5, the coordinate system of the M point is the station center rectangular coordinate system and is denoted as M-NEU. From the above, knowing the spatial rectangular coordinates of the M and S points, from the translational and rotational relationship between the two coordinate systems, we can obtain:

wherein,

$R_1=\left[\begin{array}{ccc}1& 0& 0\\ 0& -1& 0\\ 0& 0& 1\end{array}\right]---\left(16\right)$

the coordinates (N, E, U) of point S in the station-centric horizon coordinate system at point M can thus be found:

$\left[\begin{array}{c}N\\ E\\ U\end{array}\right]=\left[\begin{array}{ccc}-{\mathrm{sinB}}_M{\mathrm{cosL}}_M& -{\mathrm{sinL}}_M{\mathrm{sinB}}_M& {\mathrm{cosB}}_M\\ -{\mathrm{sinL}}_M& {\mathrm{cosL}}_M& 0\\ {\mathrm{cosB}}_M{\mathrm{cosL}}_M& {\mathrm{cosB}}_M{\mathrm{sinL}}_M& {\mathrm{sinB}}_M\end{array}\right]*\left[\begin{array}{c}{X}_S-X_M\\ Y_S-Y_M\\ Z_S-Z_M\end{array}\right]---\left(17\right)$

the azimuth angle from point M to point S is: theta as arctan (E/N) (18)

The azimuth is defined as the true azimuth. According to the true azimuth angle theta, the camera can adjust the position of the camera on the horizontal plane, and therefore the monitoring unit can accurately obtain relevant information of the ship.

Example 2

Referring to fig. 6, the present invention further provides a ship positioning method, which includes the following steps: s100: acquiring a plurality of position information of a ship from a plurality of different positioning ends; s200: sequencing the acquired position information according to priority, and sending the position information with the priority greater than a set threshold to a fusion unit; s300: fusing a plurality of position information with the priority greater than a set threshold value to obtain a unique ship longitude and latitude coordinate; s400: and acquiring a ship monitoring image according to the longitude and latitude coordinates of the ship.

Further, the position information includes the current longitude and latitude of the ship, the time of acquiring the position information, and the identifier of the positioning end. The sorting the acquired position information according to the priority includes: subtracting the current time from the time of the ship position information acquired by each positioning end to obtain the time length of the position information sent by each positioning end from the current time, and sequencing the position information according to the priority sequence of the time lengths from small to large.

In summary, in order to obtain accurate position information of a ship, the unique longitude and latitude of the ship are determined through a fusion algorithm, after the position information is obtained, a camera is adjusted, a depression angle α of the camera can be obtained through calculation, then a station center horizon coordinate system is established, and the purpose is to obtain a true azimuth angle θ of the ship relative to the camera, so that after the camera is adjusted through the depression angle α and the horizontal angle θ, relevant information of the ship can be accurately and efficiently obtained.

In the previous description, numerous specific details were set forth in order to provide a thorough understanding of the present invention. The foregoing description is only a preferred embodiment of the invention, which can be embodied in many different forms than described herein, and therefore the invention is not limited to the specific embodiments disclosed above. And that those skilled in the art may, using the methods and techniques disclosed above, make numerous possible variations and modifications to the disclosed embodiments, or modify equivalents thereof, without departing from the scope of the claimed embodiments. Any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims (8)

1. A vessel positioning system, comprising:

the positioning device comprises a position information acquisition unit, a positioning unit and a positioning unit, wherein the position information acquisition unit is used for acquiring a plurality of position information of a ship from a plurality of different positioning ends;

the sorting unit is used for sorting the acquired position information according to priority and sending the position information with the priority greater than a set threshold value to the fusion unit;

the fusion unit is used for fusing a plurality of position information with the priority level larger than a set threshold value to obtain a unique ship longitude and latitude coordinate;

the monitoring unit is used for acquiring a ship monitoring image according to the longitude and latitude coordinates of a ship;

the sorting of the acquired position information according to priority includes: subtracting the current time from the time of the ship position information acquired by each positioning end to obtain the time length of the position information sent by each positioning end from the current time, and sequencing the position information according to the priority sequence of the time lengths from small to large.

2. The system according to claim 1, wherein the position information includes a longitude and latitude where the ship is currently located, a time when the position information is obtained, and a positioning terminal identifier.

3. The vessel positioning system of claim 1, wherein the plurality of distinct positioning ends comprises: AIS, RFID, VITS, satellite positioning, and/or radar.

4. The system according to claim 1, wherein the fusing the plurality of position information with priorities greater than the set threshold to obtain the unique longitude and latitude coordinates of the ship comprises: at the current moment t, the real position of the ship at the moment is set as P^tBefore time t, the position coordinates in the position information with the priority greater than the set threshold areLet A, V, G be the three coordinates corresponding to three points respectively, and the vector velocity beAnd are respectively distant from time tCalculating the reference position of the ship at the time t according to the coordinates and the vector speedWherein:

and (B) point A:

point V:

and point G:

using the earth as a reference system, calculating A, V, G reference center and earth coordinates corresponding to the three points as (B)_A，L_A，H_A)、(B_V，L_V，H_V)、(B_G，L_G，H_G) The coordinate system takes the center of a reference ellipsoid as a coordinate origin, and the short axis of the ellipsoid is superposed with the rotating axis of the reference ellipsoid; b is the geodetic latitude, which is the included angle between the normal of the ellipsoid passing through the ground point and the equatorial plane of the ellipsoid; l is the earth longitude, and is the included angle between the ellipsoid meridian plane passing through the ground point and the initial meridian plane; h is the height of the ground;

converting geodetic coordinates into space rectangular coordinates, wherein the conversion formula is as follows:

in a space rectangular coordinate system, 1) taking a reference center O as a coordinate origin; 2) the Z axis coincides with the short axis of the reference ellipsoid; 3) the X axis is superposed with the intersection line of the initial meridian plane and the equator; 4) the Y axis is vertical to the X axis on the equatorial plane to form a right-hand rectangular coordinate system O-XYZ; in the formula (4), N is the curvature radius of the ellipsoidal unitary-ground ring, e is the first eccentricity of the ellipsoid, the long and short radii of the ellipsoids a and b, and W is the first auxiliary coefficient; wherein: a is 6378.137 km; b is 6356.7523141 km;

$N=\frac{a}{W}---\left(5\right)$

the coordinates of the A, V, G points are substituted into the formulas (5) - (7), and the spatial rectangular coordinates corresponding to A, V, G are calculated to be (X)_A，Y_A，Z_A)、(X_V，Y_V，Z_V)、(X_G，Y_G，Z_G) (ii) a Fusing A, V, G points into one point, making the point be the S point, the algorithm is as follows:

$\left\{\begin{array}{c}{X}_s=\frac{X_A+X_V+X_G}{3}\\ Y_s=\frac{Y_A+Y_V+Y_G}{3}\\ Z_s=\frac{Z_A+Z_V+Z_G}{3}\end{array}\right.---\left(8\right)$

thereby the device is provided withObtain the coordinate of the S point as (X)_S，Y_S，Z_S) (ii) a In order to obtain longitude and latitude coordinates, the space rectangular coordinates are converted into geodetic coordinates, and the conversion formula is as follows:

after the processing of the fusion unit, the unique longitude and latitude coordinate S point is obtained as (B)_S，L_S，H_S)。

5. The system according to claim 4, wherein the system for obtaining the ship monitoring image according to the longitude and latitude coordinates of the ship specifically comprises: setting the obtained longitude and latitude coordinates of the ship as an S point, and obtaining the horizontal distance a between the camera and the S point₁Distance b between camera and ground₁As is known, according to the right-angled triangle pythagorean theorem:

$c=\sqrt{{a_1}^2+{b_1}^2}---\left(10\right)$

the distance c between the camera and the point S is obtained, so that the focal length of the camera is adjusted, and according to the right-angle surface, the depression angle alpha of the camera can be determined to be:

$\mathrm{\α}=\arcsin \frac{a_1}{c}---\left(11\right)$

then, the true azimuth angle of the point S relative to the camera is calculated, namely, the horizontal included angle between the line from the true north direction line of a certain point to the target direction line along the clockwise direction is calculated, and the true azimuth angle is calculated by adopting a station-centered horizontal coordinate system; position of cameraIs M point, the geodetic coordinate of the point is (B)_M，L_M，H_M) Converted into spatial rectangular coordinates, i.e. (X), by the coordinate conversion formula (4) described above_M，Y_M，Z_M) Taking a coordinate system where the M point is located as a station center rectangular coordinate system and recording as M-NEU, knowing spatial rectangular coordinates of the M point and the S point, and obtaining the following results according to the translation and rotation relationship between the two coordinate systems:

wherein,

$R_1=\left[\begin{array}{ccc}1& 0& 0\\ 0& -1& 0\\ 0& 0& 1\end{array}\right]---\left(16\right)$

thus, the coordinates (N, E, U) of point S in the station-centric horizontal coordinate system at point M are found:

$\left[\begin{array}{c}N\\ E\\ U\end{array}\right]=\left[\begin{array}{ccc}-{\mathrm{sinB}}_M{\mathrm{cosL}}_M& -{\mathrm{sinL}}_M{\mathrm{sinB}}_M& {\mathrm{cosB}}_M\\ -{\mathrm{sinL}}_M& {\mathrm{cosL}}_M& 0\\ {\mathrm{cosB}}_M{\mathrm{cosL}}_M& {\mathrm{cosB}}_M{\mathrm{sinL}}_M& {\mathrm{sinB}}_M\end{array}\right]*\left[\begin{array}{c}{X}_S-X_M\\ Y_S-Y_M\\ Z_S-Z_M\end{array}\right]---\left(17\right)$

the azimuth angle from point M to point S is: theta as arctan (E/N) (18)

And adjusting the position of the camera according to the true azimuth angle theta.

6. A ship positioning method is characterized by comprising the following steps:

s100: acquiring a plurality of position information of a ship from a plurality of different positioning ends;

s200: sequencing the acquired position information according to priority, and sending the position information with the priority greater than a set threshold to a fusion unit;

s300: fusing a plurality of position information with the priority greater than a set threshold value to obtain a unique ship longitude and latitude coordinate;

s400: acquiring a ship monitoring image according to the longitude and latitude coordinates of a ship;

wherein, the step S200 specifically includes: subtracting the current time from the time of the ship position information acquired by each positioning end to obtain the time length of the position information sent by each positioning end from the current time, and sequencing the position information according to the priority sequence of the time lengths from small to large.

7. The ship positioning method according to claim 6, wherein the position information includes a longitude and latitude where the ship is currently located, a time when the position information is obtained, and a positioning terminal identifier.

8. The method of claim 6, wherein the plurality of different positioning ends comprises: AIS, RFID, VITS, satellite positioning, and/or radar.