A method and system for calculating a speed index

Abstract

The application provides a kind of speed index calculation method and system, the method is based on ship AIS data, when the state of ship is navigation state, sequentially carry out sequence correlation processing to all adjacent AIS data, obtain the current time, current speed, previous time and previous speed of each correlated AIS data, then calculate the time difference and navigation distance of each correlated AIS data respectively, when the current time of adjacent first AIS data point and second AIS data point in correlated AIS data point spans a certain time whole point, calculate the first time difference and navigation distance, and correct the second AIS data, obtain the corrected second AIS data, finally, calculate the average speed of ship per hour according to the total time difference and total navigation distance of all correlated AIS data points per hour, and then obtain the speed index of ship per hour, which can intuitively reflect the navigation speed in corresponding time period, and has certain reference significance for navigation planning and analysis.

Description

Technical Field

[0001] This invention relates to the fields of shipping information and intelligent technology, specifically to a method and system for calculating a speed index. Background Technology

[0002] AIS information is an important basis and information source for the study of shipping data. The Automatic Identification System (AIS) works in conjunction with the Global Positioning System (GPS) and Beidou system to broadcast ship dynamics such as position, speed, rate of change of course, and course, along with ship static data such as name, call sign, draft, and dangerous goods, via VHF channels to nearby vessels and shore stations.

[0003] A ship's speed refers to the distance it travels relative to the seabed per unit of time. It affects a ship's transportation cycle, operating costs, and competitiveness in the shipping industry, and is a crucial technical performance characteristic of transport vessels. Normal ship navigation generally refers to navigation between ports, which may include both sailing and intermediate anchorage. The speed during navigation consists of an initial starting phase, a high-speed, stable sailing phase in the middle, and a deceleration phase at the end of the voyage. Navigation speed depends on factors such as the type of ship, its power source, the amount of cargo, weather conditions, and waterway conditions.

[0004] The speed index is calculated based on information such as the ship's AIS time point, speed, and navigation status. By calculating the speed index, daily, monthly, or yearly navigation indices can be generated, intuitively reflecting the navigation speed within the corresponding time period. By comparing specific ships over time, changes in navigation efficiency can be studied, providing valuable insights for navigation planning and analysis.

[0005] Currently, the monitoring of ship speed mainly relies on manual monitoring by maritime law enforcement personnel. These personnel check the ship speed from time to time and determine if the speed is abnormal. This method cannot intuitively reflect the speed within a certain time period, and it is both time-consuming and labor-intensive, with relatively large errors. Therefore, its efficiency and accuracy are both very low. Summary of the Invention

[0006] To address the problems of current speed monitoring methods, such as the inability to intuitively reflect speed within a given time period, large errors, and low efficiency, this invention provides a speed index calculation method. Based on ship AIS data, this method processes and analyzes the AIS data using specific calculation and correction methods to obtain the ship's hourly speed index, which can intuitively reflect the ship's speed within a given time period. This invention also relates to a speed index calculation system.

[0007] The technical solution of the present invention is as follows:

[0008] A method for calculating a speed index, characterized by comprising the following steps:

[0009] Data acquisition steps: Collect the ship's AIS data and preprocess it. The AIS data includes the ship's status, speed, and sailing time.

[0010] Sailing distance calculation steps: When the ship is in a sailing state, perform sequence association processing on all adjacent AIS data points in sequence to obtain the current time, current speed, previous time and previous speed of each associated AIS data point. Calculate the time difference of each associated AIS data point based on the previous time and current time, and calculate the sailing distance of each associated AIS data point based on the time difference and previous speed.

[0011] Calculation steps for the hour parameter: When the current time of the first AIS data point and the second AIS data point that are adjacent in the associated AIS data points crosses a certain hour, the first time difference is calculated based on the hour and the current time of the first AIS data point, and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point is calculated based on the first time difference and the preceding speed of the second AIS data point.

[0012] Parameter correction steps: Correct the second AIS data point based on the hourly time, the current time of the second AIS data point, and the preceding airspeed to obtain the corrected second AIS data point;

[0013] Speed ​​index calculation steps: The first time difference and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point are included in the calculation of the average speed of the hour before the hour. The corrected second AIS data point is included in the calculation of the average speed of the hour after the hour. The average speed of the ship per hour is calculated based on the total time difference and total navigation distance of all associated AIS data points per hour. The speed index of the ship per hour is obtained based on the average speed.

[0014] Preferably, after the speed index calculation step, a speed comparison step is also included: the speed index for each day, week, month and year is calculated based on the hourly speed index of the ship, thereby obtaining the speed index curve for the corresponding time, and the speed of different ships and different fleets is compared based on the speed index curve.

[0015] Preferably, in the flight distance calculation step, the sequence association processing involves merging the parameters of the previous AIS data and the next AIS data in adjacent AIS data to obtain associated AIS data, and using the current time in the previous AIS data as the preceding time of the associated AIS data, and using the current speed in the previous AIS data as the preceding speed of the associated AIS data.

[0016] Preferably, in the step of calculating the hourly parameter, if the current time of the first AIS data point and the second AIS data point that are adjacent in the associated AIS data points spans more than two hourly times, the flight time is divided into each hourly time according to the proportion, and each hourly time is included in the average calculation of each hourly time.

[0017] Preferably, the parameter correction step, in which the second AIS data point is corrected, includes:

[0018] The second time difference is calculated based on the current time of the hour and the current time of the second AIS data point. The distance between the hour and the second AIS data point is then calculated based on the second time difference and the preceding speed of the second AIS data point.

[0019] Preferably, in the data acquisition step, the AIS data further includes the ship mobile service identification code, ship type, deadweight tonnage, and ship latitude and longitude location information. The ship type includes passenger ships, container ships, liquid bulk carriers, dry bulk carriers, general cargo ships, and special-purpose ships.

[0020] A speed index calculation system, characterized in that it comprises a data acquisition module, a navigation distance calculation module, an hourly parameter calculation module, a parameter correction module, and a speed index calculation module connected in sequence.

[0021] The data acquisition module collects and preprocesses the ship's AIS data, which includes the ship's status, speed, and sailing time.

[0022] The navigation distance calculation module performs sequential association processing on all adjacent AIS data points when the ship is in navigation state. It obtains the current time, current speed, previous time and previous speed of each associated AIS data point, calculates the time difference of each associated AIS data point based on the previous time and current time, and calculates the navigation distance of each associated AIS data point based on the time difference and previous speed.

[0023] The hour parameter calculation module calculates the first time difference based on the first time and the current time of the first AIS data point and the second AIS data point in the associated AIS data points when the current time of the first AIS data point and the second AIS data point crosses a certain hour. Then, it calculates the navigation distance between the AIS data point and the first AIS data point corresponding to the hour based on the first time difference and the preceding speed of the second AIS data point.

[0024] The parameter correction module corrects the second AIS data point based on the hourly time, the current time of the second AIS data point, and the preceding airspeed, to obtain the corrected second AIS data point.

[0025] The speed index calculation module incorporates the first time difference and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point into the calculation of the average speed for the hour preceding the hour. It also incorporates the corrected second AIS data point into the calculation of the average speed for the hour following the hour. Based on the total time difference and total navigation distance of all associated AIS data points per hour, the average speed of the ship per hour is calculated, and the speed index of the ship per hour is obtained based on the average speed.

[0026] Preferably, after the speed index calculation module, a speed comparison module is also included, which calculates the daily, weekly, monthly and yearly speed indices based on the hourly speed index of the ship, thereby obtaining the speed index curves for the corresponding time periods, and comparing the speeds of different ships and different fleets based on the speed index curves.

[0027] Preferably, in the flight distance calculation module, the sequence association processing is to merge the parameters in the previous AIS data and the next AIS data in adjacent AIS data to obtain the associated AIS data, and use the current time in the previous AIS data as the preceding time in the associated AIS data, and use the current speed in the previous AIS data as the preceding speed in the associated AIS data.

[0028] And / or, in the hourly parameter calculation module, if the current time of the first AIS data point and the second AIS data point that are adjacent in the associated AIS data points spans more than two hourly times, the flight time is divided into each hourly time according to the proportion, and each of them participates in the average calculation of each hourly time.

[0029] Preferably, in the parameter correction module, correcting the second AIS data point includes:

[0030] The second time difference is calculated based on the current time of the hour and the current time of the second AIS data point. The distance between the hour and the second AIS data point is then calculated based on the second time difference and the preceding speed of the second AIS data point.

[0031] The beneficial effects of this invention are as follows:

[0032] This invention provides a method for calculating a speed index. First, it collects the ship's AIS data, which consists of historical, authentic navigation data, ensuring the accuracy of subsequent parameter calculations. When the ship is in navigation mode, it sequentially performs sequence association processing on all adjacent AIS data points. This involves staggering the AIS data lines, performing sequence association, and defining the preceding point of each AIS data point as its predecessor point. This yields the current time, current speed, predecessor time, and predecessor speed for each associated AIS data point. Then, it calculates the time difference and navigation distance for each associated AIS data point. When the associated AIS data point is adjacent to the next... When the current time of an AIS data point and a second AIS data point crosses a certain hour, that hour is used to calculate the average parameters for the hour preceding and following that hour, respectively. The first time difference and navigation distance are calculated, and then the second AIS data point is corrected based on these calculated time differences and navigation distances to obtain the corrected second AIS data point. Finally, the average speed of the ship per hour is calculated based on the total time difference and total navigation distance of all associated AIS data points per hour. The ship's hourly speed index is then derived from the average speed, providing a clear representation of the navigation speed within the corresponding time period. This invention, through data processing and analysis of ship AIS data, provides a method for defining and implementing a ship speed index, allowing for the calculation of speed indices for individual ships or routes. Calculating the speed index for a single ship allows for comparative analysis of its operational efficiency. Calculating the speed index for specific types of ships between ports establishes navigation speed standards for those types, providing a basis for further research on the operational status of ships on that route. This invention, by comparing specific ships over time, can study changes in the ship's navigation efficiency, which has certain reference value for navigation planning and analysis.

[0033] This invention also relates to a speed index calculation system, which corresponds to the aforementioned speed index calculation method. This system can be understood as a system that implements the aforementioned speed index calculation method. It includes a data acquisition module, a navigation distance calculation module, an hourly parameter calculation module, a parameter correction module, and a speed index calculation module connected in sequence. These modules work collaboratively, using specific calculation and correction methods to process and analyze the AIS data to obtain the ship's hourly speed index. The speed index calculation involved in this invention is based on information such as the ship's AIS time point, speed, and navigation status. By calculating the hourly speed index, daily, monthly, or yearly navigation indices can be further generated, which can intuitively reflect the ship's navigation speed within the corresponding time period. Attached Figure Description

[0034] Figure 1 This is a flowchart of the speed index calculation method of the present invention.

[0035] Figure 2 This is a schematic diagram comparing the speed index of the same ship according to the present invention.

[0036] Figure 3 This is a schematic diagram comparing the speed index of similar ships according to the present invention.

[0037] Figure 4 This is a preferred structural block diagram of the speed index calculation system of the present invention. Detailed Implementation

[0038] The present invention will now be described with reference to the accompanying drawings.

[0039] This invention relates to a method for calculating the speed index, the flowchart of which is shown below. Figure 1 As shown, the steps are as follows:

[0040] The data acquisition step, or more specifically, the data acquisition and preprocessing step, involves acquiring and preprocessing the ship's AIS data. The AIS data includes the ship's status, speed, and sailing time. Specifically, the psycopg2 language in Python (a PostgreSQL database interface for Python) is used to connect to a MySQL database to retrieve the ship's AIS data. After obtaining this data, it is cleaned by deleting abnormal and duplicate data, filling in missing data, removing noise, and standardizing the data. Preferably, the AIS data also includes the ship's mobile service identification code, ship type, deadweight tonnage, and ship latitude and longitude location information. The ship type includes passenger ships, container ships, liquid bulk carriers, dry bulk carriers, general cargo ships, and special-purpose ships.

[0041] It should be noted that users can add several vessels to their fleet as needed, or classify them according to vessel type such as passenger ships, container ships, liquid bulk carriers, dry bulk carriers, general cargo ships, and special-purpose vessels, to facilitate comparative analysis between vessels in the same batch. Furthermore, based on business needs, several vessels can be tagged and categorized, such as dual-fuel vessels, wind power installation vessels, coastal dry bulk carriers, and vessels that also operate as dry bulk carriers, to enable comparative analysis of vessels operating for a specific business type.

[0042] Sailing distance calculation steps: When the ship is in a sailing state, perform sequence association processing on all adjacent AIS data points in sequence to obtain the current time, current speed, previous time and previous speed of each associated AIS data point. Calculate the time difference of each associated AIS data point based on the previous time and current time, and calculate the sailing distance of each associated AIS data point based on the time difference and previous speed.

[0043] Specifically, the time points in AIS data are discrete sampling times, and the ship's speed is also a discrete sampling time at that time. When AIS data is uploaded stably, the time interval varies from 2 minutes to one hour, with most ships having a time interval of 5 minutes. It is generally assumed that the ship's navigation data between two adjacent AIS data points is at a constant speed.

[0044] Taking Table 1 as an example, the ship with MMSI of 414777000 uploads an AIS data point approximately every 3 minutes. Assuming that between 2022-06-01 00:01:35 and 2022-06-01 00:05:04, the ship is sailing at a constant speed of 12.1 knots per hour.

[0045] Ship status is generally categorized into many types. First, ship status is classified and merged. After data classification, it is mainly divided into four types, and their meanings are as follows:

[0046] Status = 0 indicates navigation.

[0047] Status = 1 indicates anchoring

[0048] Status = 5 indicates berthing.

[0049] Status = 6 indicates stranding, operational restrictions, or other situations.

[0050] When calculating the speed index, the calculation is mainly performed on data where Status = 0, i.e., the navigation status.

[0051] Table 1

[0052]

[0053] The underlying calculation granularity of the speed index is based on hours, that is, calculating the average speed of navigation every hour. First, we perform staggered mapping of AIS data and perform sequence association. The previous point of each AIS point is defined as its predecessor point. Then, the navigation distance between two points is calculated based on the navigation speed.

[0054] When the ship is in navigation mode, all adjacent AIS data points are first sequentially associated. This involves merging the parameters of the preceding and following AIS data points, using the current time from the preceding AIS data point as the preceding time and the current speed from the preceding AIS data point as the preceding speed of the associated AIS data point. This yields the current time, current speed, preceding time, and preceding speed of each associated AIS data point. Then, the time difference for each associated AIS data point is calculated based on the preceding and current times, and the navigation distance for each associated AIS data point is calculated based on the time difference and preceding speed. The associated AIS data is shown in Table 2.

[0055] Table 2

[0056]

[0057] Calculation steps for the hour parameter: When the current time of the first AIS data point and the second AIS data point that are adjacent in the associated AIS data points crosses a certain hour, the first time difference is calculated based on the hour and the current time of the first AIS data point, and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point is calculated based on the first time difference and the preceding speed of the second AIS data point.

[0058] Specifically, when the current times of adjacent first and second AIS data points in the associated AIS data points cross a certain hour, as shown in Table 2, when calculating the average speed at the hour on June 1, 2022, the third and fourth points cross a certain hour. Therefore, it participates in both the average speed at 0:00 and the average speed at 1:00 simultaneously. This participation is achieved by splitting the AIS data of the fourth point according to the time ratio, considering both time and flight distance. Let's assume the time when two AIS points cross a certain hour is t. X Let the current time of the first AIS data point be t1, the current time of the second AIS data point be t2, the airspeed be s2, and the time difference be... Distance difference is

[0059] Then the parameters of an AIS data point at the hour X of that time are:

[0060]

[0061]

[0062] s x =s2

[0063] The AIS data point at point X on the hour needs to be included in the calculation of speed and distance for the hour preceding that hour.

[0064] Parameter correction steps: Based on the calculated first time difference and the navigation distance between the AIS data point corresponding to the hour of that time and the first AIS data point, the second AIS data point is corrected to obtain the corrected second AIS data point.

[0065] The second AIS data point is corrected to:

[0066]

[0067]

[0068] s2=s2

[0069] The corrected second AIS data point needs to be included in the speed and distance calculations for the hour following the hour at that time.

[0070] Speed ​​index calculation steps: The first time difference and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point are included in the calculation of the average speed of the hour before the hour. The corrected second AIS data point is included in the calculation of the average speed of the hour after the hour. The average speed of the ship per hour is calculated based on the total time difference and total navigation distance of all associated AIS data points per hour. The speed index of the ship per hour is obtained based on the average speed.

[0071] Suppose that at time X, there are Y AIS data points, of which N AIS data points have a Status of 0 (i.e., the ship is sailing). Excluding those not sailing, only N AIS data points are used for calculation. Therefore, the average speed at time X is... avg Calculate according to the following formula:

[0072]

[0073] In the above formula, N is the number of AIS data points at the hour X.

[0074] This invention employs data processing and analysis of ship AIS (Air Signal System) to define and implement a method for calculating ship speed indices, enabling the calculation of speed indices for individual ships or routes. Calculating the speed index for a single ship allows for comparative analysis to study its operational efficiency. Specifically:

[0075] The horizontal axis, defined by time, represents the coordinate system implemented in this invention. Because the smallest granularity of data is the hour, the speed index can be expressed on a weekly, monthly, or yearly basis. Generally, for comparing ship speeds, monthly data is the most meaningful. The monthly speed index reflects the impact of monthly operations or weather conditions on speed.

[0076] Definition of the vertical axis speed index: The vertical axis implemented in this invention is the speed index, which is the average speed during navigation within a corresponding time period. The basic data is the average speed per hour. If a certain AIS spans two hours, the navigation time is proportionally divided into two hourly segments, each participating in the hourly average calculation.

[0077] like Figure 2 The comparison of the same ship speed index and Figure 3 The annual speed index comparison of the 12000-14999TEU subtypes of container ships shown is obtained by formula (1). The speed index for each hour can be obtained by summing and averaging the speed index for each hour. Then, the speed index curve for the corresponding time (i.e., the corresponding day, week, month and year) can be obtained. The speed index curves of different ships and different fleets can be compared. In this process, it is not necessary to split the AIS points.

[0078] This invention also relates to a speed index calculation system, which corresponds to the aforementioned speed index calculation method and can be understood as a system that implements the aforementioned method, such as... Figure 4 The preferred structure shown includes a data acquisition module, a navigation distance calculation module, an hourly parameter calculation module, a parameter correction module, and a speed index calculation module connected in sequence. Specifically,

[0079] The data acquisition module collects and preprocesses the ship's AIS data, which includes the ship's status, speed, and sailing time.

[0080] The navigation distance calculation module performs sequential association processing on all adjacent AIS data points when the ship is in navigation state. It obtains the current time, current speed, previous time and previous speed of each associated AIS data point, calculates the time difference of each associated AIS data point based on the previous time and current time, and calculates the navigation distance of each associated AIS data point based on the time difference and previous speed.

[0081] The hour parameter calculation module calculates the first time difference based on the first time and the current time of the first AIS data point and the second AIS data point in the associated AIS data points when the current time of the first AIS data point and the second AIS data point crosses a certain hour. Then, it calculates the navigation distance between the AIS data point and the first AIS data point corresponding to the hour based on the first time difference and the preceding speed of the second AIS data point.

[0082] The parameter correction module corrects the second AIS data point based on the hourly time, the current time of the second AIS data point, and the preceding airspeed, to obtain the corrected second AIS data point.

[0083] The speed index calculation module incorporates the first time difference and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point into the calculation of the average speed for the hour preceding the hour. It also incorporates the corrected second AIS data point into the calculation of the average speed for the hour following the hour. Based on the total time difference and total navigation distance of all associated AIS data points per hour, the average speed of the ship per hour is calculated, and the speed index of the ship per hour is obtained based on the average speed.

[0084] Preferably, in the flight distance calculation module, the sequence association processing involves merging the parameters of the previous AIS data and the next AIS data in adjacent AIS data to obtain associated AIS data, and using the current time in the previous AIS data as the preceding time in the associated AIS data, and using the current speed in the previous AIS data as the preceding speed in the associated AIS data.

[0085] Preferably, in the hourly parameter calculation module, if the current time of adjacent first and second AIS data points in the associated AIS data points spans more than two hourly times, the flight time is proportionally divided into each hourly time point, and all of them participate in the average calculation of each hourly time point.

[0086] Preferably, after the speed index calculation module, a speed comparison module is also included, which calculates the daily, weekly, monthly and yearly speed indices based on the hourly speed index of the ship, thereby obtaining the speed index curves for the corresponding time periods, and comparing the speeds of different ships and different fleets based on the speed index curves.

[0087] Preferably, in the parameter correction module, correcting the second AIS data point includes:

[0088] The second time difference is calculated based on the current time of the hour and the current time of the second AIS data point. The distance between the hour and the second AIS data point is then calculated based on the second time difference and the preceding speed of the second AIS data point.

[0089] Preferably, the AIS data also includes the vessel's mobile service identification code, vessel type, deadweight tonnage, and vessel latitude and longitude location information, wherein the vessel type includes passenger ships, container ships, liquid bulk carriers, dry bulk carriers, general cargo ships, and special-purpose ships.

[0090] This invention provides an objective and scientific method and system for calculating ship speed index. Based on ship AIS data, it uses specific calculation and correction methods to process and analyze the AIS data to obtain the ship's hourly speed index, which can intuitively reflect the ship's sailing speed within the corresponding time period.

[0091] It should be noted that the specific embodiments described above enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. Therefore, although the present invention has been described in detail with reference to the accompanying drawings and embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. In short, all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention patent.

Claims

1. A method for calculating a speed index, characterized in that, Includes the following steps: Data acquisition steps: Collect the ship's AIS data and preprocess it. The AIS data includes the ship's status, speed, and sailing time. Sailing distance calculation steps: When the ship is in a sailing state, sequential association processing is performed on all adjacent AIS data points to obtain the current time, current speed, previous time, and previous speed of each associated AIS data point. The sequential association processing involves merging the parameters of the previous AIS data with the next AIS data to obtain associated AIS data. The current time in the previous AIS data is used as the previous time of the associated AIS data, and the current speed in the previous AIS data is used as the previous speed of the associated AIS data. The time difference of each associated AIS data point is calculated based on the previous time and the current time, and the sailing distance of each associated AIS data point is calculated based on the time difference and the previous speed. Calculation steps for the hour parameter: When the current time of the first AIS data point and the second AIS data point that are adjacent in the associated AIS data points crosses a certain hour, the first time difference is calculated based on the hour and the current time of the first AIS data point, and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point is calculated based on the first time difference and the preceding speed of the second AIS data point. Parameter correction steps: Correct the second AIS data point based on the hourly time, the current time of the second AIS data point, and the preceding airspeed to obtain the corrected second AIS data point; Speed ​​index calculation steps: The first time difference and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point are included in the calculation of the average speed of the hour before the hour. The corrected second AIS data point is included in the calculation of the average speed of the hour after the hour. The average speed of the ship per hour is calculated based on the total time difference and total navigation distance of all associated AIS data points per hour. The speed index of the ship per hour is obtained based on the average speed.

2. The method for calculating the speed index according to claim 1, characterized in that, Following the speed index calculation step, there is also a speed comparison step: the speed index for each day, week, month and year is calculated based on the hourly speed index of the ship, thereby obtaining the speed index curve for the corresponding time, and the speed of different ships and different fleets is compared based on the speed index curve.

3. The method for calculating the speed index according to claim 1, characterized in that, In the step of calculating the hourly parameter, if the current time of the first AIS data point and the second AIS data point that are adjacent after association spans more than two hourly times, the flight time is divided into each hourly time according to the proportion, and each of them participates in the average calculation of each hourly time.

4. The method for calculating the speed index according to any one of claims 1 to 3, characterized in that, The parameter correction step includes correcting the second AIS data point as follows: The second time difference is calculated based on the current time of the hour and the current time of the second AIS data point. The distance between the hour and the second AIS data point is then calculated based on the second time difference and the preceding speed of the second AIS data point.

5. The method for calculating the speed index according to claim 1, characterized in that, In the data acquisition step, the AIS data also includes the ship mobile service identification code, ship type, deadweight tonnage and ship latitude and longitude location information. The ship type includes passenger ships, container ships, liquid bulk carriers, dry bulk carriers, general cargo ships and special ships.

6. A speed index calculation system, characterized in that, It includes a data acquisition module, a navigation distance calculation module, an hourly parameter calculation module, a parameter correction module, and a speed index calculation module connected in sequence. The data acquisition module collects and preprocesses the ship's AIS data, which includes the ship's status, speed, and sailing time. The navigation distance calculation module, when the ship is in navigation mode, sequentially performs sequence association processing on all adjacent AIS data points to obtain the current time, current speed, previous time, and previous speed of each associated AIS data point. The sequence association processing involves merging the parameters of the preceding and following AIS data points to obtain associated AIS data. The current time of the preceding AIS data is used as the previous time in the associated AIS data, and the current speed of the preceding AIS data is used as the previous speed in the associated AIS data. The time difference between each associated AIS data point is calculated based on the previous time and the current time, and the navigation distance of each associated AIS data point is calculated based on the time difference and the previous speed. The hour parameter calculation module calculates the first time difference based on the first time and the current time of the first AIS data point and the second AIS data point in the associated AIS data points when the current time of the first AIS data point and the second AIS data point crosses a certain hour. Then, it calculates the navigation distance between the AIS data point and the first AIS data point corresponding to the hour based on the first time difference and the preceding speed of the second AIS data point. The parameter correction module corrects the second AIS data point based on the hourly time, the current time of the second AIS data point, and the preceding airspeed, to obtain the corrected second AIS data point. The speed index calculation module incorporates the first time difference and the navigation distance between the AIS data point corresponding to the hour and the first AIS data point into the calculation of the average speed for the hour preceding the hour. It also incorporates the corrected second AIS data point into the calculation of the average speed for the hour following the hour. Based on the total time difference and total navigation distance of all associated AIS data points per hour, the average speed of the ship per hour is calculated, and the speed index of the ship per hour is obtained based on the average speed.

7. The speed index calculation system according to claim 6, characterized in that, Following the speed index calculation module, there is also a speed comparison module, which calculates the daily, weekly, monthly and yearly speed indices based on the hourly speed index of the ship, thereby obtaining the speed index curve for the corresponding time, and comparing the speeds of different ships and different fleets based on the speed index curve.

8. The speed index calculation system according to claim 6, characterized in that, In the hourly parameter calculation module, if the current time of the first and second adjacent AIS data points in the associated AIS data points spans more than two hourly times, the flight time is proportionally divided into each hourly time point, and each of them participates in the average calculation of each hourly time point.

9. The speed index calculation system according to any one of claims 6 to 8, characterized in that, The parameter correction module includes the following steps for correcting the second AIS data point: The second time difference is calculated based on the current time of the hour and the current time of the second AIS data point. The distance between the hour and the second AIS data point is then calculated based on the second time difference and the preceding speed of the second AIS data point.

Images