Ship fleet satellite communication network system with single ship as main node

Abstract

The invention relates to the technical field of satellite communication networks, and discloses a fleet satellite communication network system taking a single ship as a main node, and the system comprises a data collection and preprocessing module which is used for collecting ship feature data at each ship end in a fleet, and carrying out the preprocessing and feature extraction, and obtaining first feature data; the centralized management and relay module is used for selecting one ship from the fleet as a main node according to the first feature data; the dynamic resource allocation module is used for calculating priority scores of the ships through a priority scoring formula according to the first feature data, and then dynamically allocating the total bandwidth of the fleet; and the fault recovery and network reconstruction module is used for triggering a main node switching mechanism and reconstructing the network when the main node fails. According to the method, a single ship is selected as a main node, centralized communication management is achieved, main node selection is optimized based on main node scores, priority scoring and a dynamic bandwidth allocation strategy are adopted, and the communication stability, the bandwidth utilization rate and the system reliability are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite communication networks, and in particular relates to a fleet satellite communication network system with a single ship as a main node. Background Art

[0002] With the rapid development of global ocean transportation, fishing operations and ocean scientific research, efficient communication between ships has become an important technical support for ensuring safe navigation and improving operational efficiency. Traditional fleet communication methods usually adopt a decentralized satellite communication architecture, that is, each ship is independently equipped with a satellite terminal and communicates directly with the satellite. However, this architecture has the following problems in practical applications: 1. Waste of resources: Each ship needs to be independently equipped with a satellite terminal, which has high equipment costs and leads to a large amount of redundant investment, especially in large-scale fleets, which increases the operational burden; 2. Low communication efficiency: In a decentralized communication mode, multiple ships are connected to the satellite communication network at the same time, resulting in intensified competition for channel resources and data transmission is susceptible to interference, especially in high-concurrency or dense sea environments, with increased delays and low bandwidth utilization; 3. Coverage blind spots: Due to antenna power limitations, small ships suffer from severe signal attenuation in bad weather or offshore environments, which may lead to communication interruptions and affect remote monitoring and dispatching commands. Summary of the invention

[0003] The present invention provides a fleet satellite communication network system with a single ship as a main node, which solves the technical problems of resource waste, low communication efficiency and coverage blind spots in related technologies.

[0004] The present invention provides a fleet satellite communication network system with a single ship as a main node, comprising:

[0005] The data collection and preprocessing module is used to collect ship characteristic data from each ship in the fleet, and perform preprocessing and feature extraction to obtain first characteristic data;

[0006] Ship characteristic data include: ship latitude and longitude, heading, speed, signal strength, bit error rate, amount of data to be transmitted and mission type;

[0007] The centralized management and relay module is used to select a ship from the fleet as a master node according to the first characteristic data. The master node is equipped with a high-performance satellite communication terminal and is responsible for centralized aggregation and relay transmission of data within the fleet.

[0008] A dynamic resource allocation module, used to calculate the priority score of the ship through a priority scoring formula according to the first characteristic data, and then dynamically allocate the total bandwidth of the fleet;

[0009] The fault recovery and network reconstruction module is used to trigger the master node switching mechanism and rebuild the network when the master node fails.

[0010] Furthermore, the latitude and longitude of the ship are represented by two-dimensional coordinate codes. The task types include: ordinary data transmission, navigation command transmission, real-time monitoring data transmission, emergency event notification, and the task urgency is set according to the task type. The task type and task urgency are both represented by real number codes.

[0011] Furthermore, the specific steps of the pretreatment include:

[0012] S201, using a rule verification method to identify abnormal values ​​in each data field of the ship characteristic data, and using the mean of the data other than the abnormal values ​​for replacement processing;

[0013] S202, using a first-order exponential smoothing filter to process the signal strength;

[0014] S203, converting each data field of the ship characteristic data into a unified digital format and adding a timestamp.

[0015] Furthermore, the specific steps of feature extraction include:

[0016] S301, extracting communication quality features according to ship feature data, wherein a first intermediate feature is obtained by dividing the difference between the signal strength of the ship and the lowest signal strength in the fleet by the difference between the highest and lowest signal strengths in the fleet, a second intermediate feature is obtained by the logarithmic ratio of the bit error rate of the ship and the highest bit error rate in the fleet, a third intermediate feature is obtained by the absolute value of the difference between the ship's heading and the average heading of the fleet, and the first intermediate feature, the second intermediate feature and the third intermediate feature are combined to obtain a communication quality feature;

[0017] S302, extracting a position stability feature according to the ship feature data, wherein a fourth intermediate feature is obtained by the ratio of the difference between the speed of the ship and the average speed of the fleet and the difference between the maximum speed and the minimum speed in the fleet, and the position stability feature is obtained by combining the Euclidean distance between the ship and the center point of the fleet, the fourth intermediate feature and the third intermediate feature;

[0018] S303, extracting motion stability features according to the ship feature data, wherein a fifth intermediate feature is obtained by the difference between the ship's heading and the ship's heading at the last moment, a sixth intermediate feature is obtained by the ratio of the absolute value of the difference between the ship's speed and the ship's speed at the last moment and the difference between the maximum speed and the minimum speed in the fleet, a seventh intermediate feature is obtained by the ratio of the absolute value of the ship's acceleration and the maximum acceleration of the ship, and the fifth intermediate feature, the sixth intermediate feature and the seventh intermediate feature are combined to obtain a motion stability feature;

[0019] S304, normalizing the communication quality features, the position stability features, and the motion stability features using a z-score normalization method.

[0020] Furthermore, the communication quality characteristics, position stability characteristics, and motion stability characteristics extracted from the ship feature data are used to obtain the ship master node score through the first ship scoring formula, and the ship with the highest master node score is selected as the master node, and the ship with the second highest master node score is selected as the backup master node, wherein the ship master node score is obtained by performing power operations on the communication quality characteristics, position stability characteristics, and motion stability characteristics, respectively, and performing product operations.

[0021] Furthermore, the variances of the communication quality feature, position stability feature, and motion stability feature are calculated respectively, and the weight coefficient of each feature is calculated based on the ratio of the variance of each feature to the sum of the variances of all features. The weight coefficient of each feature includes: communication quality weight coefficient, position stability weight coefficient, and motion stability weight coefficient.

[0022] Further, the priority score of the ship is calculated according to the first characteristic data by a priority score formula, and then the total bandwidth of the fleet is allocated, wherein the priority score is obtained by combining the ratio of the amount of data to be transmitted of the ship to the maximum amount of data to be transmitted in the fleet, the signal strength of the ship to the highest signal strength in the fleet, the logarithm of the bit error rate of the ship, and the urgency of the task of the ship;

[0023] The total bandwidth of the fleet is allocated according to the priority score, and the calculation formula for the allocatable bandwidth of the ship is: ,in, represents the allocatable bandwidth of ship i, represents the total bandwidth of the fleet, represents the priority score of ship i, n represents the number of ships in the fleet, and j represents the ship index.

[0024] Furthermore, when the master node meets one of the following conditions, the master node is determined to be invalid:

[0025] The signal strength of the master node is lower than a first preset threshold and lasts longer than a first preset time interval;

[0026] The bit error rate of the master node is higher than a second preset threshold and lasts longer than a second preset time interval;

[0027] The heading deviation of the master node exceeds a third threshold value and lasts for a period of time exceeding a third preset time interval;

[0028] After determining that the master node fails, the master node switching mechanism is executed, and the switching mechanism includes:

[0029] First priority switch: enable the backup master node to replace the current master node;

[0030] Second priority switching: When the backup master node fails, the master node score is recalculated based on the current fleet status, and the ship with the highest master node score is selected as the new master node.

[0031] The beneficial effects of the present invention are as follows: by selecting a single ship as the master node, the present invention reduces the need for each ship to be independently equipped with a satellite communication terminal, thereby reducing equipment procurement and maintenance costs and avoiding redundant investment in a traditional distributed communication architecture;

[0032] Based on the three core features of communication quality, position stability and motion stability, the present invention selects the best ship as the master node through the master node scoring algorithm, and selects the suboptimal node as the backup master node in advance; this mechanism ensures that the master node has good signal quality, reasonable fleet position and stable motion state, avoids the problem of frequent switching of the master node, and improves the reliability and stability of the fleet communication network;

[0033] The present invention adopts a priority scoring formula to calculate the priority according to the ship's data transmission requirements, link quality and task urgency, and ensures that high-priority tasks get bandwidth first through a dynamic bandwidth allocation strategy. Compared with the traditional fixed bandwidth allocation method, this method can adjust resource allocation according to the real-time needs of the ship, improve bandwidth utilization, reduce channel competition, and improve the stability and response speed of data transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a module schematic diagram of a fleet satellite communication network system with a single ship as a main node according to the present invention. DETAILED DESCRIPTION

[0035] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that the discussion of these embodiments is only to enable those skilled in the art to better understand and implement the subject matter described herein, and the functions and arrangements of the elements discussed may be changed without departing from the scope of protection of the contents of this specification. Each example may omit, replace or add various processes or components as needed. In addition, the features described relative to some examples may also be combined in other examples.

[0036] like Figure 1 As shown, a fleet satellite communication network system with a single ship as the main node includes:

[0037] The data collection and preprocessing module 101 is used to collect ship characteristic data from each ship in the fleet, and perform preprocessing and feature extraction to obtain first characteristic data;

[0038] Ship characteristic data include: ship latitude and longitude, heading, speed, signal strength, bit error rate, amount of data to be transmitted and mission type;

[0039] The centralized management and relay module 102 is used to select a ship from the fleet as a master node according to the first characteristic data. The master node is equipped with a high-performance satellite communication terminal and is responsible for centralized aggregation and relay transmission of data within the fleet.

[0040] A dynamic resource allocation module 103, configured to calculate the priority score of the ship through a priority scoring formula according to the first characteristic data, and then dynamically allocate the total bandwidth of the fleet;

[0041] The fault recovery and network reconstruction module 104 is used to trigger the master node switching mechanism and rebuild the network when the master node fails.

[0042] In one embodiment of the present invention, the data acquisition and preprocessing module deploys sensors, communication equipment and data processing units at each ship end to realize data acquisition and preprocessing; wherein, the Beidou satellite navigation system is used to obtain the longitude and latitude of the ship, the inertial navigation system is used to obtain the current heading of the ship, the ship speed is obtained through the speed measurement function of the global navigation satellite system, the radio receiving module is used to obtain the ship signal strength, the test data is transmitted between the ship and the main node, the bit error rate is calculated, the shipboard computer monitors the data buffer area, the amount of data to be transmitted is obtained, and the task type is obtained through the shipboard task management system.

[0043] In one embodiment of the present invention, the latitude and longitude of the ship are represented by two-dimensional coordinate coding, and the task types include: normal data transmission, navigation command transmission, real-time monitoring data transmission, and emergency event notification. The task urgency is set according to the task type. The task type and the task urgency are both represented by real number coding. For example, the task type and the task urgency are represented by 1 to 4. When the task type is navigation command transmission, the task urgency is 2.

[0044] In one embodiment of the present invention, the specific steps of the pre-processing include:

[0045] S201, using a rule verification method to identify abnormal values ​​in each data field of the ship characteristic data, and use the mean value of the data other than the abnormal value for replacement processing, for example, the ship's longitude and latitude data is verified for legitimacy, and the latitude range is set to: , the range of longitude is: If the longitude and latitude data of a ship exceeds the range, it is regarded as an outlier and replaced with the average longitude and latitude of other ships in the fleet; physical constraints are judged on the heading and speed data, and the value range of the heading is set to: If the heading exceeds the value range, it is regarded as an abnormal value and the average heading of other ships in the fleet is used for replacement. The speed value range is set to: If the speed exceeds the range, the average speed of other ships in the fleet is used for replacement;

[0046] S202, using a first-order exponential smoothing filter to process the signal strength. Specifically, the calculation formula of the first-order exponential smoothing filter is: ,in, Indicates the signal strength after processing at the current time t, represents the signal strength at the current time t, represents the smoothing coefficient, represents the signal strength after processing at time t-1, where t represents the index of the time;

[0047] S203, converting each data field of the ship characteristic data into a unified digital format and adding a timestamp. Specifically, the unit of the ship's latitude and longitude is unified as degrees, the unit of the speed is unified as knots, and the unit of the heading is unified as degrees. The range is , the unit of signal strength is dBm, and the range of bit error rate is , the unit of the amount of data to be transmitted is unified as bytes.

[0048] In one embodiment of the present invention, the specific steps of feature extraction include:

[0049] S301, extracting communication quality features according to the ship feature data, the calculation formula of the communication quality features is: ,in, Indicates the communication quality characteristics, used to evaluate the communication link quality of the ship, , and denote the first weight coefficient, the second weight coefficient and the third weight coefficient respectively, and , and The sum is 1. The first weight coefficient is used to measure the impact of the ship's signal strength on the communication quality characteristics. The second weight coefficient is used to adjust the contribution of the bit error rate in the communication quality characteristics. The third weight coefficient is used to evaluate the impact of the ship's heading consistency on the communication quality. represents the signal strength of ship i, and Respectively represent the lowest signal strength and the highest signal strength in the fleet, represents the bit error rate of ship i, represents the highest bit error rate in the fleet, represents a minimum value between 0 and 1, preferably, Set to , represents the heading of ship i, represents the average heading of the fleet, represents the absolute value of the difference between the heading of ship i and the average heading of the fleet;

[0050] S302, extracting position stability characteristics according to the ship characteristic data, the calculation formula of the position stability characteristics is: ,in, It represents the position stability feature, which is used to evaluate the relative position of the ship in the fleet, ensure that the master node is in the center area of ​​the fleet, reduce the overall communication overhead, and improve the link stability. and denote the longitude and latitude of ship i, respectively. and They represent the longitude and latitude of the center point of the fleet respectively. The center point of the fleet is obtained by taking the average longitude and latitude of all ships in the fleet. and denote the fourth weight coefficient and the fifth weight coefficient respectively, and and The sum is 1, the fourth weight coefficient is used to measure the importance of the ship's position relative to the center of the fleet, and the fifth weight coefficient is used to adjust the influence weight of the heading in the position stability feature. represents the speed of ship i, represents the average speed of the fleet, represents the maximum speed of ship i, represents the minimum speed of ship i;

[0051] S303, extracting motion stability features according to the ship characteristic data, the motion stability features are calculated as follows: ,in, Indicates the motion stability feature, which is used to quantify the smoothness of the ship's navigation, ensure the stability of the motion state of the main node, and avoid excessive heading deviation affecting communication. , and denote the sixth weight coefficient, the seventh weight coefficient and the eighth weight coefficient respectively, and , and The sum is 1, the sixth weight coefficient is used to measure the importance of ship heading stability, the seventh weight coefficient is used to evaluate the role of ship speed stability in motion stability characteristics, and the eighth weight coefficient is used to adjust the weight of ship acceleration in motion stability characteristics. represents the heading of ship i at the previous moment, represents the speed of ship i at the previous moment, It represents the acceleration of ship i, which is calculated by dividing the absolute value of the difference between the current speed of ship i and the previous speed by the time interval between the current time and the previous time. represents the maximum acceleration of ship i;

[0052] S304, normalizing the communication quality features, the position stability features, and the motion stability features using a z-score normalization method.

[0053] In one embodiment of the present invention, the ship master node score is obtained by a first ship scoring formula according to the communication quality feature, position stability feature, and motion stability feature extracted from the ship feature data, and the ship with the highest master node score is selected as the master node, and the ship with the second highest master node score is selected as the backup master node, wherein the first ship scoring formula is: , represents the master node score of ship i, , and denote the communication quality weight coefficient, the position stability weight coefficient and the motion stability weight coefficient, respectively, and , and The sum is 1. The communication quality weight coefficient is used to reflect the influence of communication quality characteristics on the selection of the master node. The position stability weight coefficient is used to reflect the importance of the ship in the center of the formation. The motion stability weight coefficient is used to reflect the influence of the ship's navigation stability on the selection of the master node.

[0054] In one embodiment of the present invention, the variances of the communication quality feature, the position stability feature, and the motion stability feature are calculated respectively, and the weight coefficient of each feature is calculated according to the ratio of the variance of each feature to the sum of the variances of all features. The weight coefficient of each feature includes: a communication quality weight coefficient, a position stability weight coefficient, and a motion stability weight coefficient; specifically, the calculation formula of the communication quality weight coefficient is: , the calculation formula of the position stability weight coefficient is: , the calculation formula of motion stability weight coefficient is: ,in, represents the variance of the communication quality characteristics, represents the variance of the positional stability, The variance representing the stability of the motion.

[0055] In one embodiment of the present invention, by calculating the variance of communication quality characteristics, position stability characteristics, and motion stability characteristics, the influence on the selection of the main node is adjusted according to the degree of dispersion of the characteristics in the fleet, so that the system can adapt to different marine environments and fleet distribution conditions.

[0056] In one embodiment of the present invention, the priority score of the ship is calculated by a priority score formula according to the first feature data, and then the total bandwidth of the fleet is allocated, wherein the priority score formula is: , represents the priority score of ship i, , and represent the data transmission weight coefficient, link quality weight coefficient and task urgency weight coefficient respectively, and , and The sum is 1, represents the amount of data to be transmitted by ship i, Indicates the maximum amount of data to be transmitted within the fleet, Indicates the mission urgency of ship i;

[0057] The total bandwidth of the fleet is allocated according to the priority score, and the calculation formula for the allocatable bandwidth of the ship is: ,in, represents the allocatable bandwidth of ship i, represents the total bandwidth of the fleet, represents the priority score of ship i, n represents the number of ships in the fleet, and j represents the ship index.

[0058] In one embodiment of the present invention, the bandwidth is dynamically adjusted according to the current amount of data to be transmitted, link quality and task urgency of the ship, ensuring that high-priority tasks obtain bandwidth first and improving communication efficiency; the master node score is not affected by short-term task requirements, ensuring long-term network stability, and the priority score focuses on immediate bandwidth requirements, so that the system can maintain stability and quickly adjust resource allocation strategies under instantaneous high load conditions to improve network status performance.

[0059] In one embodiment of the present invention, when the master node meets one of the following conditions, it is determined that the master node is invalid:

[0060] 1. The signal strength of the master node is lower than the first preset threshold and the duration exceeds the first preset time interval;

[0061] 2. The bit error rate of the master node is higher than the second preset threshold and the duration exceeds the second preset time interval;

[0062] 3. The heading deviation of the master node exceeds the third threshold value and lasts for longer than the third preset time interval;

[0063] After determining that the master node fails, the master node switching mechanism is executed, and the switching mechanism includes:

[0064] First priority switch: enable the backup master node to replace the current master node;

[0065] Second priority switching: When the backup master node fails, the master node score is recalculated based on the current fleet status, and the ship with the highest master node score is selected as the new master node.

[0066] In one embodiment of the present invention, by judging the status of the master node based on three angles: signal strength, bit error rate and heading deviation, the possibility of misjudgment or missed judgment is reduced, and a two-layer strategy of first-priority standby master node switching and second-priority dynamic reselection of the master node is adopted to ensure that the network can recover quickly under any circumstances.

[0067] The embodiments of the present invention are described above, but the present invention is not limited to the above-mentioned specific implementation modes. The above-mentioned specific implementation modes are merely illustrative and not restrictive. Under the guidance of the present embodiment, ordinary technicians in this field can also make many forms, which are all within the protection of the present embodiment.

Claims

1. A fleet satellite communication network system with a single ship as the main node, characterized in that: include: The data collection and preprocessing module is used to collect ship characteristic data from each ship in the fleet, and perform preprocessing and feature extraction to obtain first characteristic data; Ship characteristic data include: ship latitude and longitude, heading, speed, signal strength, bit error rate, amount of data to be transmitted and mission type; The centralized management and relay module is used to select a ship from the fleet as a master node according to the first characteristic data. The master node is equipped with a high-performance satellite communication terminal and is responsible for centralized aggregation and relay transmission of data within the fleet. A dynamic resource allocation module, used to calculate the priority score of the ship through a priority scoring formula according to the first characteristic data, and then dynamically allocate the total bandwidth of the fleet; The fault recovery and network reconstruction module is used to trigger the master node switching mechanism and rebuild the network when the master node fails.

2. A fleet satellite communication network system with a single ship as the main node according to claim 1, characterized in that: The latitude and longitude of the ship are represented by two-dimensional coordinate codes. The task types include: ordinary data transmission, navigation command transmission, real-time monitoring data transmission, emergency event notification, and the task urgency is set according to the task type. The task type and task urgency are both represented by real number codes.

3. A fleet satellite communication network system with a single ship as the main node according to claim 1, characterized in that: The specific steps of the pretreatment include: S201, using a rule verification method to identify abnormal values ​​in each data field of the ship characteristic data, and using the mean of the data other than the abnormal values ​​for replacement processing; S202, using a first-order exponential smoothing filter to process the signal strength; S203, converting each data field of the ship characteristic data into a unified digital format and adding a timestamp.

4. A fleet satellite communication network system with a single ship as the main node according to claim 2, characterized in that: The specific steps of feature extraction include: S301, extracting communication quality features according to ship feature data, wherein a first intermediate feature is obtained by dividing the difference between the signal strength of the ship and the lowest signal strength in the fleet by the difference between the highest and lowest signal strengths in the fleet, a second intermediate feature is obtained by the logarithmic ratio of the bit error rate of the ship and the highest bit error rate in the fleet, a third intermediate feature is obtained by the absolute value of the difference between the ship's heading and the average heading of the fleet, and the first intermediate feature, the second intermediate feature and the third intermediate feature are combined to obtain a communication quality feature; S302, extracting a position stability feature according to the ship feature data, wherein a fourth intermediate feature is obtained by the ratio of the difference between the speed of the ship and the average speed of the fleet and the difference between the maximum speed and the minimum speed in the fleet, and the position stability feature is obtained by combining the Euclidean distance between the ship and the center point of the fleet, the fourth intermediate feature and the third intermediate feature; S303, extracting motion stability features according to the ship feature data, wherein a fifth intermediate feature is obtained by the difference between the ship's heading and the ship's heading at the last moment, a sixth intermediate feature is obtained by the ratio of the absolute value of the difference between the ship's speed and the ship's speed at the last moment and the difference between the maximum speed and the minimum speed in the fleet, a seventh intermediate feature is obtained by the ratio of the absolute value of the ship's acceleration and the maximum acceleration of the ship, and the fifth intermediate feature, the sixth intermediate feature and the seventh intermediate feature are combined to obtain a motion stability feature; S304, normalizing the communication quality features, the position stability features, and the motion stability features using a z-score normalization method.

5. A fleet satellite communication network system with a single ship as the main node according to claim 4, characterized in that: The communication quality characteristics, position stability characteristics, and motion stability characteristics extracted from the ship feature data are used to obtain the ship master node score through the first ship scoring formula, and the ship with the highest master node score is selected as the master node, and the ship with the second highest master node score is selected as the backup master node. The ship master node score is obtained by performing power operations on the communication quality characteristics, position stability characteristics, and motion stability characteristics, and performing product operations.

6. A fleet satellite communication network system with a single ship as the main node according to claim 5, characterized in that: The variances of the communication quality feature, position stability feature, and motion stability feature are calculated respectively, and the weight coefficient of each feature is calculated according to the ratio of the variance of each feature to the sum of the variances of all features. The weight coefficients of each feature include: communication quality weight coefficient, position stability weight coefficient, and motion stability weight coefficient.

7. A fleet satellite communication network system with a single ship as the main node according to claim 4, characterized in that: Calculate the priority score of the ship through the priority scoring formula according to the first characteristic data, and then allocate the total bandwidth of the fleet, wherein the priority score is obtained by combining the ratio of the amount of data to be transmitted of the ship to the maximum amount of data to be transmitted in the fleet, the signal strength of the ship to the highest signal strength in the fleet, the logarithm of the bit error rate of the ship, and the urgency of the mission of the ship; The total bandwidth of the fleet is allocated according to the priority score, and the calculation formula for the allocatable bandwidth of the ship is: ,in, represents the allocatable bandwidth of ship i, represents the total bandwidth of the fleet, represents the priority score of ship i, n represents the number of ships in the fleet, and j represents the ship index.

8. A fleet satellite communication network system with a single ship as the main node according to claim 5, characterized in that: When the master node meets one of the following conditions, the master node is considered invalid: The signal strength of the master node is lower than a first preset threshold and lasts longer than a first preset time interval; The bit error rate of the master node is higher than a second preset threshold and lasts longer than a second preset time interval; The heading deviation of the master node exceeds a third threshold value and lasts for a period of time exceeding a third preset time interval; After determining that the master node fails, the master node switching mechanism is executed, and the switching mechanism includes: First priority switch: enable the backup master node to replace the current master node; Second priority switching: When the backup master node fails, the master node score is recalculated based on the current fleet status, and the ship with the highest master node score is selected as the new master node.

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