Traffic flow basic chart drawing method and device based on ship displacement and medium

Abstract

The application relates to a traffic flow basic map drawing method and device based on ship displacement and a medium. After initial data is acquired and preprocessed, ship feature data is extracted, the ship displacement is calculated, and the driving distance and time of different ships are corrected; based on the driving distance of different ships and the corresponding ship displacement in a selected period, the ship traffic flow rate in a full space-time region is calculated; based on the driving time of different ships and the corresponding ship displacement in a selected voyage section, the ship traffic flow density in the full space-time region is calculated; based on the ship traffic flow rate and the ship traffic flow density, the ship traffic flow speed is calculated; based on the ship traffic flow rate, the density and the speed, the ship traffic flow basic map is drawn; and the full space-time region is determined by the selected period and the selected voyage section. Compared with the prior art, the application has the advantages of improving the accuracy of key parameters of ship traffic flow, the authenticity of the traffic flow basic map and the like.

Description

Technical Field

[0001] This invention relates to the field of ship traffic flow technology, and in particular to a method, apparatus and medium for drawing basic traffic flow diagrams based on ship displacement. Background Technology

[0002] Maritime transport has become the main mode of freight transport in my country. The development of maritime transport has also promoted innovation and progress in shipbuilding technology, with a significant trend towards specialization, larger size, higher speed, and greater intelligence in vessels. Changes in the number, type, size, and speed of vessels have led to greater complexity in maritime traffic flows. Under these circumstances, the limited navigable water resources inevitably lead to increased maritime traffic risks and more maritime accidents. Therefore, how to balance navigation safety and efficiency, and maximize the utilization of navigable water resources, is a key issue for the sustainable development of waterway transportation. This requires effective methods to collect maritime traffic data and to conduct statistical and theoretical research on this data to understand the basic characteristics and general patterns of maritime traffic flows from both macroscopic and microscopic perspectives.

[0003] Currently, there is a wealth of research on the measurement, definition, solution, and fundamental relationships of basic traffic flow parameters (flow rate q, density k, and speed v) in road traffic, and this field has reached a relatively mature stage. Among these, Edie's definition constructs a spatiotemporal region, providing a common foundation for q, k, and v, and ensuring the existence of the fundamental relationship q = k × v among the basic characteristics of traffic flow. This model is widely used. q = k × v is also known as the Edie model and is used to describe ship traffic flow. In ship traffic flow, the solutions for q, k, and v are often based on methods used in road traffic. When solving for the basic characteristic parameters of ship traffic flow—flow rate, density, and speed—statistical analysis of the number of ships is essential. However, due to the extremely complex composition of waterway traffic, the diverse types and sizes of ships, the varying water space occupied by different ships, and the significant impact of large ships, statistical analysis of ship traffic cannot be merely quantitative. It must be conducted through a conversion standard to perform a unified qualitative and quantitative analysis of ship traffic. In maritime traffic research, ships within a certain scale range are often selected as "standard ships" for conversion. The conversion factors are mostly based on ship length or gross tonnage, and different conversion factors are assigned to ship types of other scales to calculate the equivalent traffic volume of the ship. The conversion factors are determined using a combination of quantitative and qualitative methods. Therefore, the conversion result is not "equal to" but only "equivalent to".

[0004] A search revealed that Chinese patent CN 112967526B discloses a method for drawing a basic maritime traffic flow map based on AIS data. This method involves selecting a study channel and establishing a channel coordinate system, acquiring and cleaning AIS data, converting the ship's latitude and longitude coordinates to determine the average ship length and beam in the channel, statistically analyzing the initial abscissa values ​​of ships entering the channel, subdividing the channel, drawing the spatiotemporal trajectory of ships within the channel, calculating maritime traffic flow characteristic parameters, and determining its key characteristic parameters to draw a basic maritime traffic flow map. This method extracts the free-flow velocity and congestion density of maritime traffic flow from historical AIS data, enabling the creation of a relatively complete basic traffic flow map. However, it does not consider the scale differences between ships when calculating the maritime traffic flow characteristic parameters, resulting in deviations between the drawn basic maritime traffic flow map and the actual situation. Therefore, improving the accuracy and realism of the drawn basic maritime traffic flow map is a problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art in terms of low accuracy and realism when drawing basic traffic flow maps, and to provide a method, apparatus and medium for drawing basic traffic flow maps based on ship displacement.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] According to a first aspect of the present invention, a method for drawing a basic traffic flow diagram based on ship displacement is provided, the method comprising the following steps:

[0008] S1. Acquire and preprocess initial data, extract ship characteristic data, and calculate ship displacement based on ship characteristic data. The ship displacement is used to correct the travel distance and travel time of different ships.

[0009] S2, based on different ship travel distances and corresponding ship displacements within a selected time period, calculates the ship traffic flow rate in the entire time and space area;

[0010] S3, based on different ship travel times and corresponding ship displacements within the selected waterway segment, calculates the ship traffic flow density in the entire time and space area;

[0011] S4, based on the ship traffic flow rate and ship traffic flow density, calculates the ship traffic flow velocity;

[0012] S5. Based on the calculation results of ship traffic flow rate, ship traffic flow density and ship traffic flow speed, draw the basic ship traffic flow map;

[0013] The full-time and space-time region is determined by selecting a time period and a flight segment.

[0014] As a preferred technical solution, the process of calculating the ship's displacement includes the following: the displacement of a single ship is the product of water density and the ship's displacement volume, the displacement volume is the product of the ship's hull coefficient and its hull displacement volume, and the hull displacement volume is the product of the ship's block coefficient, length, beam, and draft.

[0015] As a preferred technical solution, the ship traffic flow rate within the entire time and space area is a first characteristic value within a unit of the entire time and space area, where the first characteristic value is the ship travel distance corrected by the ship displacement; the ship traffic flow density within the entire time and space area is a second characteristic value within a unit of the entire time and space area, where the second characteristic value is the ship travel time corrected by the ship displacement.

[0016] As a preferred technical solution, the full-time and space-time region includes multiple sub-time and space-time regions. In the sub-time and space-time regions where the time period is determined, the travel distance of different ships is different, and in the sub-time and space-time regions where the voyage segment is determined, the travel time of different ships is different.

[0017] As a preferred technical solution, the ship's trajectory is reconstructed using the preprocessed initial data, and a spatiotemporal trajectory map of the ship is drawn to obtain the travel distance and travel time of each ship in each sub-spatiotemporal region.

[0018] As a preferred technical solution, the process of preprocessing the initial data includes data filtering and data cleaning. The data filtering includes extracting the corresponding latitude and longitude information from the initial data and determining whether it meets the storage conditions. The data cleaning includes removing duplicate data and filling in missing data, and finally obtaining the preprocessed data. The initial data is obtained through the AIS system.

[0019] As a preferred technical solution, the latitude and longitude information is converted into the corresponding position of the ship in the rectangular coordinate system based on the transformation of the rectangular coordinate system, so as to solve the ship's travel distance from the preprocessed data.

[0020] As a preferred technical solution, the basic traffic flow map includes a speed-density submap, a speed-flow rate submap, and a flow rate-density submap.

[0021] According to a second aspect of the present invention, a traffic flow basic map drawing apparatus based on ship displacement is provided, comprising a memory, a processor, and a program stored in the memory, wherein the processor executes the program to implement the method described herein.

[0022] According to a third aspect of the present invention, a storage medium is provided having a program stored thereon, which, when executed, implements the method described thereon.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. In the process of redefining and solving traffic flow parameters, this invention considers the differences in ship dimensions and introduces ship displacement as the unit of measurement instead of the number of ships. It then defines the flow rate, density, and speed of ship traffic flow. This not only restricts the three parameters to a spatiotemporal region and ensures the basic relationship between the parameters, but also avoids the problems of selecting a "standard ship" and determining conversion coefficients. This simplifies the solution process and improves the accuracy of calculating key parameters of ship traffic flow and the accuracy of drawing basic traffic flow maps.

[0025] 2. In redefining traffic flow rate and density, this invention determines the entire time and space area based on the selected time period and route, and considers the traffic conditions of the sea lanes in the entire time and space area based on the different travel time and distance of each ship, effectively improving the completeness and authenticity of the basic map of maritime traffic flow. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the implementation process of the method in this embodiment of the invention;

[0028] Figure 3 This is a schematic diagram of the waterway rectangular coordinate system in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram illustrating the principle of latitude and longitude coordinate transformation in an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the spatiotemporal trajectory of a ship within a single sub-spatiotemporal region in an embodiment of the present invention;

[0031] Figure 6 This is a basic traffic flow diagram drawn in an embodiment of the present invention. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0033] like Figure 1 As shown, this embodiment provides a method for drawing a basic traffic flow map based on ship displacement. It redefines the basic characteristic parameters of ship traffic flow based on the Edie model, providing support for drawing a basic maritime traffic flow map and facilitating the understanding of the basic characteristics and general patterns of the waters of interest. For example... Figure 2 As shown, the implementation of this method in this embodiment specifically includes the following steps:

[0034] Step S1: Acquire and preprocess initial data, extract ship characteristic data, and calculate the ship displacement based on the ship characteristic data. This ship displacement is used to correct the travel distance and travel time for different ships. Specific steps include:

[0035] S11, Selecting the data source. In this embodiment, a section of the Nancao Channel in Shanghai Port is selected as the data source, and initial data is obtained through AIS (Automatic Identification System). The geographical location information of the selected channel is shown in Table 1. The time range of the selected data is from January 1, 2021 to January 15, 2021.

[0036] Table 1. Geographical location information of a certain section of the Nancao Channel in Shanghai Port

[0037]

[0038]

[0039] S12, Preprocessing the initial data, specifically including data filtering and data cleaning. During data filtering, a Python program was used to extract AIS data from January 2021, extracting the latitude and longitude information from each AIS record and determining whether it falls within the selected latitude and longitude range of the Nancao waterway. If so, the data record was saved. During data cleaning, duplicate data was removed, missing data was filled in, and the necessary AIS data types, such as ship MMSI code, time, ship length, beam, draft, longitude, and latitude, were saved.

[0040] Step S2: Based on the different ship travel distances and corresponding ship displacements within the selected time period T, calculate the ship traffic flow rate q for the entire time and space region. 船 Ship traffic flow rate q 船 These are redefined maritime traffic flow parameters. The redefinition process involves referencing the method used in road traffic to calculate traffic flow using data from fixed-point detectors, and redefining it based on ship displacement. Specifically, in road traffic, road traffic flow is defined as the number of vehicles passing through a road observation point per unit time, i.e.

[0041]

[0042] Where, q 车 Let N0 be the road traffic flow rate, T0 be the number of vehicles passing through the road observation point within the observation period, and N0 be the observation time. Based on this, in maritime traffic, ship displacement is used instead of the number of ships as the unit of measurement, and the ship traffic flow rate is initially defined as:

[0043]

[0044] At this point, the ship traffic flow rate represents the ship displacement passing through the channel observation point per unit time. In the above formula, q 船 Let N be the vessel traffic flow rate, and D be the number of vessels passing through the entire time and space area. i Let be the displacement of the i-th ship. D is the sum of the displacements of N ships; i =ρ 水 ×V i , ρ 水 V is the density of water. i Let be the displacement volume of the i-th ship; k i Let be the hull coefficient of the i-th ship. Let be the displacement volume of the i-th ship; c i Let l be the block coefficient of the i-th ship. i Let w be the captain of the i-th ship. i Let d be the width of the i-th ship. i Let be the draft of the i-th ship.

[0045] Based on the ship traffic flow rate q 船 The initial definition involves constructing a sub-spacetime region |A| using infinitesimally small distances. q Specifically, for the ship traffic flow rate q 船 Multiply both the numerator and denominator by dx, where dx represents an infinitesimal distance for q. 船 The deformation is shown below:

[0046]

[0047] Where, the denominator |A| q The area of ​​the rectangle bounded by time interval T and an infinitesimal distance dx can be considered as a sub-spacetime region; molecule Indicates that in the sub-spacetime region |A| q Within the sub-spacetime region |A|, the sum of the distances traveled by all ships with a certain displacement, with the ship displacement used as a coefficient to correct the distance traveled by each ship; q In this context, each ship travels the same distance, which is dx.

[0048] Sub-spacetime region |A| q Expanding to the entire time and space region |A|, we obtain the ship traffic flow rate q considering the displacement of each ship. 船 The final definition. Specifically, expanding the infinitesimal distance dx to the flight segment L, we obtain the entire spacetime region |A|=L×T, then:

[0049]

[0050] Where, the denominator |A| represents the area of ​​the rectangle enclosed by time period T and flight segment L, which is a spatiotemporal region; the numerator This represents the total distance traveled by all ships with a certain displacement within the entire spatiotemporal region |A|, with the ship displacement serving as a coefficient to correct the travel distance of each ship. Within the entire spatiotemporal region |A|, the travel distance of each ship is not necessarily the same; that is, for the multiple sub-spatiotemporal regions contained within the entire spatiotemporal region, the travel distance of ships in each sub-spatiotemporal region is not necessarily the same within the time period T.

[0051] Step S3: Based on the different ship travel times and corresponding ship displacements within the selected waterway segment L, calculate the ship traffic flow density k in the entire time and space region. 船 Ship traffic flow density k 船 These are redefined maritime traffic flow parameters. The redefinition process involves referencing methods used in road traffic to calculate traffic density using spatial detector data, and redefining them based on ship displacement. Specifically, in road traffic, road traffic flow density is defined as the number of vehicles observed per unit length of a lane at a given instant.

[0052]

[0053] Where, k 车 To represent road traffic flow density, N0′ is the number of vehicles passing through the observed length in a given instant, and L0 is the observed length. Based on this, in maritime traffic, ship displacement is used instead of the number of ships as the unit of measurement, and ship traffic flow density is initially defined as:

[0054]

[0055] At this point, the ship traffic flow density represents the ship displacement observed per unit length of a waterway at a given instant. In the above formula, k... 船 For ship and road traffic flow density, N and D i , The meaning is the same as the meaning in the preliminary definition of ship traffic flow rate in step S2.

[0056] Based on the preliminary definition of ship traffic flow density, an infinitesimally small time period is used to construct a sub-spatial region |A|. k Specifically, for ship traffic flow density, the numerator and denominator are multiplied by dt, where dt represents an infinitesimally small time interval for k. 船 The deformation is shown below:

[0057]

[0058] Where, the denominator |A| kThe area of ​​the rectangle bounded by flight segment L and an infinitesimally small time interval dt can be considered as a sub-spacetime region; molecule Indicates that in the sub-spacetime region |A| k Within this region, the total travel time of all ships with a certain displacement is calculated, with displacement used as a coefficient to correct for each ship's travel time. In the sub-spacetime region |A| k In this context, each ship travels for the same amount of time, dt.

[0059] Sub-spacetime region |A| k Expanding to the entire time and space region |A|, we obtain the ship traffic flow density k considering the displacement of each ship. 船 The final definition. Specifically, expanding the infinitesimal time dt to a time interval T, we obtain the entire spatiotemporal region |A|=L×T, then:

[0060]

[0061] Where, the denominator |A| represents the area of ​​the rectangle enclosed by time period T and flight segment L, which is a spatiotemporal region; the numerator This represents the total travel time of all ships with a certain displacement within the entire spatiotemporal region |A|, with the ship displacement serving as a coefficient to correct the travel time of each ship. Within the entire spatiotemporal region |A|, the travel time of each ship is not necessarily the same. That is, for the multiple sub-spatiotemporal regions contained within the entire spatiotemporal region, the travel time of ships in each sub-spatiotemporal region within the navigation segment L is not necessarily the same.

[0062] Step S4, based on the ship traffic flow rate q 船 and ship traffic flow density k 船 The ship traffic flow velocity v was calculated. 船 .

[0063] Based on the identity q = k × v in the Edie model, the ship traffic flow velocity v is obtained. 船 The final definition is:

[0064]

[0065] In steps S2 to S4, in order to calculate the flow rate, density, and speed of ship traffic using the actual acquired data, it is first necessary to establish a Cartesian coordinate system for the waterway. This is because the ship travel distance required to solve for the basic characteristic parameters of traffic flow cannot be directly obtained from AIS data; therefore, a Cartesian coordinate system needs to be established on the selected waterway segment as the basis for coordinate transformation. For example... Figure 3 As shown, a rectangular coordinate system is established with point 1 as the origin, and the positive direction of the x-axis is set to the same direction as the waterway. Next, a latitude and longitude coordinate transformation is performed. For example... Figure 4As shown, point 1 is selected as the reference point for coordinate transformation, with latitude and longitude of (31.373°N, 121.612°E), denoted as . Point P represents the real-time position of the ship in the waterway, and its latitude and longitude are denoted as follows: Using the Mercator method of navigation, the real-time distance S between the ship and the origin (reference point) can be calculated using the ship's real-time latitude and longitude provided by AIS data. Then, based on... Figure 4 The trigonometric relationships in the equation can be used to calculate the ordinate (X) of the real-time position of ship P. i This value is necessary for solving the basic characteristic parameters of traffic flow. The relevant calculation formula is as follows:

[0066] X i =S cosθ (1)

[0067]

[0068]

[0069]

[0070] D λ =λ i -λ0 (5)

[0071] DMP = MP2 - MP1 (6)

[0072]

[0073] Among them, X i θ is the vertical coordinate of the ship in the rectangular coordinate system of the waterway; θ is the angle between the straight line connecting the ship's position point and the origin and the direction of the waterway; S is the straight-line distance between the ship and the origin of the coordinate system, i.e., the voyage. C is the latitude difference; D is the heading angle; λ DMP represents the difference in longitude; MP2 represents the difference in latitude gradient; MP1 represents the latitude gradient of the real-time position of the ship; and MP1 represents the latitude gradient of the reference point.

[0074] Step S5, based on the ship traffic flow rate q 船 Ship traffic flow density k 船 and ship traffic flow speed v 船 Based on the calculation results, a basic diagram of ship traffic flow is drawn. The specific steps are as follows:

[0075] S51, Determine the spatiotemporal region: The spatial range of a single spatiotemporal region is the length of the selected flight segment, denoted as L; the time range is one hour as a time window, denoted as T.

[0076] S52, Draw a ship's spatiotemporal trajectory diagram: (e.g.) Figure 5As shown, taking the data of a selected section of the Nancao Channel in Shanghai Port as an example, a spatiotemporal trajectory of a ship within a spatiotemporal region is constructed. In the figure, time is the horizontal axis and the distance traveled by the ship in the X direction is the vertical axis.

[0077] S53, Calculate the travel distance and time of each ship in each spatiotemporal region: Use Python to write a program to divide the spatiotemporal region sequentially within the selected data source range and calculate the start and end points of the ship trajectory on the target spatiotemporal boundary, and determine the travel distance Δx and travel time Δt of each ship in the target spatiotemporal region.

[0078] S54, Remove reverse traffic flow data: (e.g.) Figure 5 As shown, there may be ships traveling in the opposite direction (against the X direction) within the spatiotemporal region. Such data needs to be removed before calculating the basic characteristic parameters of ship traffic flow.

[0079] S55, Solving for basic traffic flow characteristic parameters: After data processing, the travel distance and time of each ship within the target spatiotemporal region are obtained. Combined with the ship length, beam, and draft data from the AIS data, the displacement is calculated. Substituting these values ​​into the formula yields the ship traffic flow rate, density, and speed. The parameter calculation is based on the definition method of basic ship traffic flow characteristics based on the Edie model, as shown below:

[0080]

[0081]

[0082]

[0083] Where |A|=L×T is a spatiotemporal region; D i Let Δx be the displacement of the i-th ship within the spacetime region; i Let Δt be the distance traveled by the i-th ship within the spatiotemporal region; i Let be the travel time of the i-th ship within the spatiotemporal region.

[0084] S56, Draw a basic traffic flow map based on the solution results. For example... Figure 6 As shown, this basic traffic flow map includes three sub-maps. Figure 6 (a) is the velocity-density subplot. Figure 6 (b) is the velocity-flow rate subplot. Figure 6 (c) is the flow rate-density subplot. The basic maritime traffic flow map obtained by using the redefined traffic flow parameters can provide researchers with a more accurate method for analyzing and managing maritime traffic.

[0085] The method provided in this embodiment does not perform a statistical analysis of the number of ships, but instead introduces ship displacement to calculate the basic characteristic parameters of traffic flow: flow rate, density, and speed. This method directly reflects ship displacement in the definition of basic characteristics of road traffic flow based on the Edie model. This not only confines the three parameters of ship traffic flow to a spatiotemporal region, ensuring fundamental relationships, but also avoids the problems of selecting a "standard ship" and determining conversion coefficients. It considers differences in ship scale when solving for ship traffic flow rate, density, and speed, enriching the research on the macroscopic characteristics of ship traffic flow. Specifically, this method adjusts the generalized definition of basic characteristics of road traffic flow in the Edie model and applies it to maritime traffic flow, avoiding the standard ship conversion problem, considering ship scale, and completing a redefinition of ship traffic flow characteristics, thus enriching the theory of ship traffic flow.

[0086] Furthermore, this embodiment provides a traffic flow basic map drawing device based on ship displacement, including a memory, a processor, and a program stored in the memory, which executes the program to implement the aforementioned method. The device includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or loaded from the memory unit into a random access memory (RAM). The RAM can also store various programs and data required for device operation. The CPU, ROM, and RAM are interconnected via a bus. An input / output (I / O) interface is also connected to the bus. Multiple components in the device are connected to the I / O interface, including: input units, such as a keyboard, mouse, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as disks, optical disks, etc.; and communication units, such as network interface cards, modems, wireless transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks. The processor executes the various methods and processes described above, such as steps S1 to S5. For example, in some embodiments, steps S1 to S5 may be implemented as a computer software program tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps S1 to S5 described above may be performed. In other embodiments, the CPU may be configured to execute methods S1 to S5 by any other suitable means (e.g., by means of firmware). The functions described above may be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that may be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SOCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0087] Furthermore, this embodiment also provides a storage medium on which a program is stored, which, when executed, implements the aforementioned method. The program code for implementing the method can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0088] In the context of this invention, a computer-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0089] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for drawing a basic traffic flow map based on ship displacement, characterized in that, Includes the following steps: S1. Acquire and preprocess initial data, extract ship characteristic data, and calculate ship displacement based on ship characteristic data. The ship displacement is used to correct the travel distance and travel time of different ships. S2, based on different ship travel distances and corresponding ship displacements within a selected time period, calculates the ship traffic flow rate in the entire time and space area; S3, based on different ship travel times and corresponding ship displacements within the selected waterway segment, calculates the ship traffic flow density in the entire time and space area; S4, based on the ship traffic flow rate and ship traffic flow density, calculates the ship traffic flow velocity; S5. Based on the calculation results of ship traffic flow rate, ship traffic flow density and ship traffic flow speed, draw the basic ship traffic flow map; The full-time and space-time area is determined by selecting a time period and a flight segment; The ship traffic flow rate within the entire time and space area is the first characteristic value within a unit of the entire time and space area, where the first characteristic value is the ship travel distance corrected for ship displacement; the ship traffic flow density within the entire time and space area is the second characteristic value within a unit of the entire time and space area, where the second characteristic value is the ship travel time corrected for ship displacement. The full-time-space region includes multiple sub-time-space regions. Within a sub-time-space region where the time period is defined, the travel distance of different ships is different. Within a sub-time-space region where the route segment is defined, the travel time of different ships is different.

2. The method for drawing a basic traffic flow map based on ship displacement according to claim 1, characterized in that, The process of calculating the ship's displacement includes the following: the displacement of a single ship is the product of the water density and the ship's displacement volume, the displacement volume is the product of the ship's hull coefficient and the hull form displacement volume, and the hull form displacement volume is the product of the ship's block coefficient, length, beam, and draft.

3. The method for drawing a basic traffic flow map based on ship displacement according to claim 1, characterized in that, Using the preprocessed initial data, the ship's trajectory is reconstructed, and a spatiotemporal trajectory map of the ship is drawn to calculate the travel distance and travel time of each ship in each sub-spatiotemporal region.

4. The method for drawing a basic traffic flow map based on ship displacement according to claim 1, characterized in that, The process of preprocessing the initial data includes data filtering and data cleaning. Data filtering includes extracting the corresponding latitude and longitude information from the initial data and determining whether it meets the storage conditions. Data cleaning includes removing duplicate data and filling in missing data, and finally obtaining the preprocessed data. The initial data is obtained through the AIS system.

5. The method for drawing a basic traffic flow map based on ship displacement according to claim 4, characterized in that, Using a Cartesian coordinate system as the basis for transformation, the latitude and longitude information is converted into the corresponding position of the ship in the Cartesian coordinate system, which is used to solve the ship's travel distance from the preprocessed data.

6. The method for drawing a basic traffic flow map based on ship displacement according to any one of claims 1-5, characterized in that, The basic traffic flow graph includes a velocity-density subgraph, a velocity-flow rate subgraph, and a flow rate-density subgraph.

7. A device for drawing a basic traffic flow map based on ship displacement, comprising a memory, a processor, and a program stored in the memory, characterized in that, When the processor executes the program, it implements the method as described in any one of claims 1-6.

8. A storage medium having a program stored thereon, characterized in that, When the program is executed, it implements the method as described in any one of claims 1-6.

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