RU2281529C1 - Method of visualization of navigational situation in ship handling - Google Patents

Abstract

FIELD: ship handling.

SUBSTANCE: proposed method includes storage of electronic radar chart of terrain, determination of radar antenna position, correlation of specific features of terrain and points of interest; electronic radar chart of terrain is formed during processing radar information and is stored in form of sequence of radar images recorded during test run of ship equipped with surveillance radar, personal computer, equipment for tie-in of surveillance radar with personal computer and equipment of satellite navigational system. Then, present radar image is compared with electronic radar chart to estimate deviation of ship from preset route and reliability of information received from satellite navigational system and surveillance radar. Position of surveillance radar antenna, coordinates of radar image centers used for forming electronic radar chart of terrain and center of present radar image are determined by tie-in of surveillance radar with personal computer and satellite navigational system, with display of ship's position, her coordinates, heading and speed at superposition of present radar image whose center is tied-in to geographic coordinates determined by satellite navigational system, registration of image with navigational electronic chart on geospatial information carrier where visualization of change of actual depth in fixed point of water basin in time is carried out, isolines of maximum tide fluctuations and surface of tide fluctuations, height of tide are plotted. Some areas of water basin where actual depth is lesser than permissible magnitude (draft plus safe depth) are determined. Structure of storage of geospatial information includes conversion of flat scanning of Earth to multilevel embedded squares each of which is indexed by code which is just longer Guilbert's curve for this square. Index thus found is used for finding objects having index with prefix equal to index of preset area.

EFFECT: enhanced efficiency.

Description

The invention relates to the field of navigation and can be used in the development of autopilot, during hydrographic work, to improve the safety of tankers.

Known visual navigation devices in which the assessment of the navigation situation is carried out by comparing the current radar image with a radar map [1], which requires a lot of personal experience of the skipper, as in the radar hack and in the radar image there is no exact reference to the coordinates.

A known method of visualizing the navigation environment, in which the current radar image is combined with an approximated electronic navigation map, the original information of which is stored on a magnetic or hard medium [2]. The use of these maps is fraught with certain difficulties, since they are made by the developer of the navigation complex for each specific navigation area according to preliminary applications.

There is also known a method of visualizing the navigation environment, in which the current radar image is superimposed on a traditional navigation map, the image of which is captured using a television camera [3]. The method is time-consuming, since it is burdened with manual operations associated with the replacement of cards, it requires the alignment of the television camera to be fulfilled and, when the navigation situation is changed promptly, does not provide corrective input.

In the known method for visualizing the navigation environment by means of a device containing a radar antenna, a block for storing a location map, a compass, a block for determining the position of a radar antenna, an indicator, an input unit for determining the point of interest, and a controller that creates a radar scan on the indicator screen and image of a map of the area and places the point of interest on the radar scan at the corresponding point on the map of the area, resulting in a radar These goals, the characteristic features of the terrain, and the point of interest can be correlated [4].

The disadvantage of this technical solution is the need to compare the information obtained in various systems, since the characteristic point on the ground is compared with the radar image, while the characteristic point may be in the center of the radar image.

There are also a number of technical solutions for visualizing the navigation environment, based on the pairing of electronic cartographic navigation systems with a radar image, as well as autopilot, and external (radio navigation and satellite navigation systems) and autonomous navigation tools (direction indicator, log, echo sounder) [5, 6]. Due to the fact that these technical solutions use the overlay of the current radar image, the center of which is tied to geographic coordinates determined by external navigation systems, the information content of navigation parameters is significantly increased on the navigation electronic map and graphical display of the ship's trajectory, as well as movement in advance selected route (programmed swimming).

However, existing electronic navigation charts are usually recorded at the factory of the equipment and stored on ROM disks. No more than seven electronic charts can be stored on one diskette [7], which makes it possible to use well-known systems for visualizing the navigation situation mainly in navigation areas not burdened by numerous navigation dangers on a traditional navigation map. As rightly emphasized in [8, p.2], “currently available navigation electronic maps cover a small part of the territory of the Russian Federation”, which limits the use of these systems, despite their higher information content compared to the radar image of the area.

There is also known a method for visualizing the navigational situation during navigation [8], in which the visualization of the navigational situation during navigation is carried out by creating, at a control passage of the vessel along a given path, an electronic radar map of the area, in the form of a sequence of radar images, the coordinates of the centers of which are determined using the satellite navigation system, overlay on it of the current radar images obtained during the passage of the vessel along a given trajectory, coordinates the centers of which are also received from the satellite navigation system, and the subsequent assessment of the coincidence of the current radar image and the electronic radar map of the area, which is used to judge the deviation of the vessel from the given route and the reliability of the information received from the satellite navigation system and the radar all-round, the position of the radar antenna circular view, the coordinates of the centers of radar images used to create an electronic radar map of the area, and the center of the current radar image defined by conjugation circular scanning radar apparatus PC and SNA. Moreover, the achieved technical result of the invention is to increase the accuracy and reliability of the displayed navigation information.

Using the known method for visualizing the navigational situation during navigation for vessels of small displacement really gives a positive effect. However, when using it on ships of large displacement due to the presence of "dead zones" during the operation of the radar all-round visibility, due to the height of the antenna, as well as interference arising from the construction of deck superstructures, especially when navigating in navigational constraints, the probability of obtaining reliable radar information is significantly reduced.

In addition, this method allows to achieve a technical result when using it when navigating a vessel in the coastal zone, since a radar map of the area can be created with the confident capture of a radar with a circular view of coastal navigation aids or at least a coastline. In the open sea, the creation of an electronic map of the area using radar information by means of a control pass of the vessel is practically not feasible, due to the lack of coastal landmarks.

For vessels of large displacement, and especially for vessels carrying dangerous goods, when passing narrow places, fairways and when approaching remote devices of gas and oil terminals, the amount of output information characterizing the navigation safety of navigation in these areas should be redundant and continuous to make the only right decision for ensure navigational safety of navigation.

The objective of the proposed technical solution is to increase the reliability of the displayed navigation information by expanding the functionality of the method.

The problem is solved due to the fact that in the method of visualizing the navigational situation during navigation, which includes storing an electronic radar map of the area, determining the position of the antenna of a radar station (radar) of a circular view, correlation of the characteristic features of the area and points of interest, when applying the current radar image to an electronic radar a map of the area, taking into account the position of the radar antenna of the all-round view, while the electronic radar map of the area provide radar information during processing and save it as a sequence of radar images recorded during the control passage of a given trajectory by a vessel equipped with a radar for all-around viewing, a personal computer, equipment for interfacing radar for all-round viewing with a personal computer and equipment for satellite navigation system (SNA), while the coordinates of the centers of radar images used to build an electronic radar map of the area, get from the SNA, and when applying the current radar image to the electronic the radar radar map, the center of the current radar image is also obtained from the SNA and placed at the point with the corresponding coordinates on the electronic terrain map, after which the coincidence of the current radar image and the electronic radar map of the area is judged by which the deviation of the vessel from the given route and reliability are judged information received from the SNA and the radar all-around, and the position of the antenna radar all-round, the coordinates of the centers of the radar image n, used to create an electronic map of the area, and the center of the current radar image is determined by pairing the radar of a circular view with a personal computer and SNA equipment, displaying the position of the vessel, its coordinates, speed, course when superimposing the current radar image, the center of which is tied to geographical coordinates defined SNA, combining a radar image with a navigation electronic map recorded on a geospatial information medium in which the change is visualized in time of the actual depth at a fixed point in the water area, the construction and visualization of isolines of the largest range of tidal oscillations and the surface of tidal waves, tidal heights according to astronomical conditions, the definition and visualization of areas of the water area for a certain point in time at which the actual depth is less than permissible (draft plus safe depth ), and the storage structure of geospatial information includes the transformation of a flat surface of the Earth into hierarchical nested squares, each of which s is indexed code being the Hilbert curve for a length of the square, determination index on the minimum square area that completely contains the specified area, and based on the found index find objects having the prefix index equal to the index of the predetermined area.

Distinctive features, in comparison with the known methods for visualizing the navigational situation, are that they visualize changes in time of the actual depth at a fixed point in the water area, construct and visualize contours of the largest in terms of astronomical magnitude range of tidal oscillations and the surface of tidal oscillations, the height of the tide in time, the determination and visualization of areas of the water area for a certain point in time, at which the actual depth is less than permissible, and the storage structure is geo spatial information includes the conversion of a flat scan of the Earth's surface into hierarchical nested squares, each of which is indexed by a code that is the length of the Hilbert curve for this square, determining the index of the minimum square area that completely contains a given area, and objects that have an index with prefix equal to the index of a given area, which allows you to store a significant amount of cartographic information with the ability to quickly enter the necessary rrektury due to change navigation situation, to perform a procedure of automatic natural generalization of objects defined by the geographic coordinates at their visualization software with the possibility of switching from one card to another scale to estimate the margin of error for a particular scale.

In the known methods for visualizing the navigational situation during navigation, in order to achieve a technical result consisting in increasing the accuracy and reliability, it is necessary to store a large amount of data on a permanent medium. The problem of data storage is that to solve the visualization problem, geospatial information needs to be loaded into RAM. In the general case, the large amount of geospatial information does not allow downloading it completely in the operational case, in the particular case, if it can be done in ship conditions, then the time required for downloading exceeds the permissible value. In addition, it should be borne in mind that large volumes of geospatial information loaded into RAM dramatically slow down the operation of a PC. The solution to this problem is associated with the organization of a special structure for storing geospatial information on an external medium, and special algorithms for searching and selecting in this storage structure only that set of geospatial data that is necessary to solve a specific current navigation problem.

Traditional ways of presenting information in a relational form are not effective, since geospatial information is multidimensional. Existing representations of multidimensional data in the form of multidimensional information trees (for example, a k-d-B-tree) are also not effective in terms of time spent searching and selecting for output to visualization.

In the claimed technical solution, the presentation of vector geospatial information is based on the form of the mapping of points of multidimensional space to points of a one-dimensional segment-Hilbert curve. This mapping allows you to build an effective structure for storing multidimensional information on an external medium and query procedure algorithms with the fulfillment of requirements to minimize memory and time.

In addition, for large vessels carrying dangerous goods, the actual navigational depth and tide height are essential navigation parameters to ensure safe navigation, especially in conditions that are difficult to navigate. In the known methods for visualizing the navigational situation during navigation, if tidal fluctuations can be taken into account, then only for individual coastal points for which harmonic constants are known. The extrapolation of the point values of the tide in open waters is illegal, since tidal fluctuations in the open waters of the seas have a complex spatiotemporal distribution.

The method is implemented as follows.

When the vessel moves along the route, as in the known method [8], they compare the information about the current position and the electronic radar map obtained by determining the parameters by means of radar all-round visibility and SNA equipment.

Combine on the screen of the visualization device a radar map of the area with an electronic navigation map, which is stored on an external medium such as a CD or hard drive. Storage on an external medium is carried out using a B-tree, based on the hierarchical principle of storage, which consists in the following:

- a flat scan of the Earth’s surface is divided into hierarchical nested squares, similar to the construction of the Hilbert curve. Each square is indexed by a code that is the length of the Hilbert curve for that square;

- geospatial objects are scanned and the index of the minimum quadrant in area, which completely contains the object, is determined. The object is assigned the index of the found quadrant.

To search in a given spatial region, the search principle is as follows:

- the index of the smallest quadrant in area is determined, which completely contains the given area;

- the found index contains objects that have an index with a prefix equal to the index of a given area.

In this case, only objects intersecting with a given area are loaded and each quadrant has a certain resolution level (visualization scale), which allows for large areas to not load small objects by setting a limit on the length of the index suffix.

When changing the positioning of a given area (scanning the viewing window), the set of small quadrants first of all changes, while the set of large quadrants remains unchanged. Therefore, large objects do not need to be overloaded, but only relatively small objects for the current scale are searched and loaded. The same is true when zooming in the visualization window. At the same time, loading only the minimum necessary set of objects can support several different scales of visualization of one area. Since the location of the indices in the index file is sequential, accessing the external memory is a one-time process for reading the index search.

The structure of storing geospatial data on an external medium includes a metadata file, an index file (links between objects and hierarchical quadrants of partition), a file describing objects in quadrants), a file with geospatial data (coordinates and attributes), both of the original objects and generalized, which allows increase the amount of memory and build a flexible query processing system that takes into account the current available RAM size and the realized speed of operations that provide query processing.

The structure of the layer metadata file includes the minimum fragmentation index, the range of hierarchical storage indices in RAM, the number of layers, layer serial number, layer code, layer name, layer type (point, linear, polygon), initial scale, number of storage files, serial number, scale , names (path) of the storage file, the maximum diameter of the object, the minimum distance, the number of gradations of scales, the number of cartographic signs, serial number, upper scale, lower scale link to the cartographic sign.

The structure of the index file (for all layers) includes a hierarchical square index (start index 0), the initial data offset in the object description file squared, the final data offset in the object description file squared.

The description file of objects in quadrants includes a hierarchical index of the square, a data code (there are objects, no objects in the square), and if there are objects, then the number of layers, the serial number of the layer, the code of the layer, the number of objects commensurate with the size of the square, ordinal object number, object code in the layer. object type (the entire object, part of the object, the square completely falls into the polygon, code of the underlying polygon, fill value, number of scales, scale ordinal number, scale value, initial offset of data about the object in the data storage file for the entire object or serial number of the starting point for a partial object, the final offset of data about the object in the data storage file for the entire object, links to objects are lower in level.

Information about geophysical objects, in addition to spatio-temporal coordinates, includes a vector of characteristics that describe the geophysical entity of the object itself. In the general case, each object has its own set of these characteristics, which are both a digital and text data type. Since the search for an object by a given vector (exact match problem) or subvector (exact match search problem) is a complex algorithmic problem, to solve it, a suffix tree is constructed with the vector of characteristics represented as a string.

The procedure for automatic generalization of natural linear objects is implemented in the MatLab language.

Linear objects on the navigation map are represented by ordered sets of geographical coordinates. The number of coordinate pairs in the set corresponds to the original map scale. When moving to a smaller map scale, it is necessary to reduce, according to the scale of generalization, the number of pairs of geographical coordinates that describe the object. For this, a procedure for eliminating the number of points is provided, which allows you to save the visible structure of the tortuosity of the line, and for area objects - the area. A procedure that satisfies these requirements is a concept of arranging points for representativeness in the formation of a graphic image of an object and consists in the following.

Each linear object (line or polygon) occupies an area corresponding to the area of its convex hull. A set of points of the convex hull of an object is that minimal set of points that represents an object at a minimum scale. This set can be visualized only if the area in pixels of the convex hull is greater than a certain given value (free parameter). When increasing the scale from the scale corresponding to the visualization of the convex hull to the original map scale, the number of approximation points should increase, so that new points replenish the list of already visualized ones, which is carried out as follows.

When zooming in for each rendered pair of points, there is a point farthest from the line connecting this pair of points. If this distance is greater than the permissible error on this scale, then the point is visualized, otherwise not. This procedure is a modification of the algorithm for estimating the global fractal dimension of a curve. Therefore, the power law of changing the length of the line remains invariant by construction, and therefore, for polygons the area will change little, since the area of the triangles that are “randomly” added or “subtracted” at each step is quite small. At the same time, the number of points describing the curve changes dramatically. This procedure can be performed at the preprocessing stage, and at each iteration step, save the distance from the added point to the corresponding straight line. Since the implementation of this procedure can lead to intersection of lines, then after it is completed, intersections are checked and corrected by assigning to points forming intersecting sections such a large distance value that does not lead to intersection. If the distances for the points are known, then the generalization procedure itself is reduced to estimating the permissible error for the visualization scale, choosing points for which the distance is greater than or equal to the error value, and visualizing the curve based on these points.

During automatic generalization of artificial objects (fenced special training grounds and recommended swimming routes), due to the fact that there are not many such objects, they are classified according to their importance, according to which their visualization is regulated by scale. In this case, the preprocessing procedure is reduced to calculating its length for each object and creating a list of object indices in increasing order of lengths. In addition, for the entire layer of objects, the total area of objects is calculated, equal to the sum of the products of the length of each object and the surface area of the Earth corresponding to one pixel in the original map scale.

The visualization procedure consists in the fact that for the entire layer the total area of objects is calculated, equal to the sum of the products of the length of each object and the surface area of the Earth corresponding to one pixel in the current map scale. Only those objects are visualized whose total area is equal to the area for the original map scale. For this, a list of indices obtained at the pre-processing stage is used.

In addition to visualizing the cartographic information on the navigational chart, the actual depth is also determined, visualized and stored in a file on a given ship trajectory by predicting tides using a numerical method for calculating the spatio-temporal distribution of tidal fluctuations in an open water area by harmonic constants at coast observation posts above sea level, which makes it possible to pre-calculate the actual depth of the sea as the sum of tidal fluctuations and navigation (cartographic) depth at any point in the sea at any time. This ensures the calculation of the actual depth of the sea at any point at any time; identification and mapping of areas of the water area where the actual depth for any tidal situation will be less than permissible, always more than acceptable and areas occupying an intermediate position (in these areas, actual depths may be less and more than acceptable depth depending on the phase of the tide); identification and mapping of areas of the water area for a certain point in time at which the actual depth is less than permissible (draft plus safe depth); determination and visualization of changes in time of actual depth at a fixed point in the water area; construction of isolines of the largest in terms of astronomical magnitude range of tidal fluctuations in the water area, isolines of tidal fluctuations; construction and visualization of the surface of tidal fluctuations in the water area; animation of the position of isolines and the surface of the tide height over time in the water area.

In contrast to the known methods for visualizing the navigational situation during navigation, the claimed method provides the possibility of visualizing not only a radar map of the area, but also a practically un simplified navigation map with their combination, as well as visualization of tidal fluctuations in the waters of the seas, which increases the reliability of navigation. The application of this method is especially relevant for ships carrying dangerous goods. The method can also be used during hydrographic work. Practical implementation of the method was carried out in the waters of the North Sea.

Information sources

1. Sazonov A.E., Rodionov A.I. Navigation automation. M., Transport, 1977, p.194-196.

2. Pirogov NN, Chernyavets VV Navigation complex for hydrofoil boats / Foreign Military Review, No. 4, 1986, p. 58-59.

3. Solntsev A.N., Pirogov N.N. ANKN-94 Automated Navigation System / Notes on hydrography. L., GUNIO MO RF №244, 1988, p.29-33.

4. US Patent No. 5,179,385.

5. EX-NAVI-SAILOR, CJSC TRANSAS, E-mail: tel@transas.ru.

6. The current state and development trends of foreign means and navigation systems of moving objects of military and civil purposes. / Aleksandrov AS, Arno G.R., Vasilieva T.E. et al. L., GUNIO MO RF, 1994, p. 92-100.

7. Receiver indicator GP-1500. Prospectus of the company "Decca Radar", 1989.

8. RF patent No. 2207585.

Claims (1)

A method for visualizing the navigational situation during navigation, including storing an electronic radar map of the area, determining the position of the antenna of the radar station (radar) of the all-round view, correlating characteristic features of the area and points of interest, when overlaying the current radar image on the electronic radar map of the terrain taking into account the position of the antenna of the radar all-around while an electronic radar map of the area is created when processing radar information and save in the form of a sequence of radar images recorded during the control passage of a given trajectory by a vessel equipped with a circular viewing radar, a personal computer, equipment for pairing a circular viewing radar with a personal computer and satellite navigation system (SNA) equipment, while the coordinates of the centers of the radar images used to construct the electronic radar maps of the area are received from the SNA, and when the current radar image is superimposed on an electronic radar map of the area, the center of of the current radar image is also obtained from the SNA and placed at a point with the corresponding coordinates on the electronic terrain map, after which the coincidence of the current radar image and the electronic radar map of the area is judged by which the deviation of the vessel from the given route and the reliability of the information received from the SNA are judged and Radar circular view, and the position of the antenna radar circular view, the coordinates of the centers of the radar images used to create electronic radar of the terrain map, and the center of the current radar image is determined by pairing the all-round radar with a personal computer and SNA equipment, displaying the position of the vessel, its coordinates, course, speed when applying the current radar image, the center of which is tied to the geographical coordinates determined by the SNA, the combination of the radar image with a navigation electronic map recorded on an external carrier of geospatial information, characterized in that when the vessel moves along the route it is combined on the visualization device’s crane using a radar all-around radar and SNA equipment with a navigation electronic map stored on an external medium visualizes the time changes in the actual depth at a fixed point in the water area, constructs and visualizes contours of the largest tidal range in astronomical conditions and surface of tidal fluctuations, tidal heights in time, definition and visualization of areas of the water area for a certain time nor at which the actual depth is less than acceptable, while the representation of geospatial information on a navigation electronic map of the area stored on an external medium is based on the display of points of multidimensional space of a given spatial region of the vessel’s route in the form of points of a one-dimensional segment representing a Hilbert curve by dividing a flat surface Earth into hierarchical nested squares, with each square being indexed by a code corresponding to the length of the Hilbert curve for this square drata, and the range of hierarchical indices is stored in the random access memory of an external medium of geospatial information, to search for a given spatial area of geospatial and geophysical objects, look at the available objects on the screen of the visualization device and determine the index of a minimum square area that completely contains a given spatial region from the found the index find objects having an index equal to the index of a given spatial area.