A method for finely determining the state of ships of Pacific saury in the North Pacific by multi-threshold hybrid determination

Abstract

The present invention discloses a method for finely determining the state of vessels catching Pacific saury in the North Pacific by multi-threshold hybrid determination. The state of each vessel position is judged through a combination of VMS data, operation time, and marine environment. By multi-threshold hybrid determination of the vessel state of saury vessels, the vessel state can be more finely distinguished. The VMS data includes speed, course difference, and position difference; the operation time is the local time in the North Pacific; the marine environment is wind and wave data. Due to the adoption of the above technical solution, compared with the prior art, the present invention has the following advantages and positive effects: The present invention determines the vessel state of saury vessels by multi-threshold hybrid determination. Since the trajectory of saury vessels changes greatly during fishing operations, different from other fishing vessels, by mixing and determining with multiple thresholds, the vessel state can be more finely distinguished.

Description

Technical Field

[0001] The present invention relates to the technical field of the application of Pacific saury vessel data, and particularly to a method for finely determining the state of Pacific saury vessels with multiple thresholds mixed judgment. Background Art

[0002] The Vessel Monitoring System (VMS) is a comprehensive application system integrating Global Positioning System (GPS) technology, Electronic Map (GIS) technology, Electronic Chart Display and Information System (ECDIS) technology, computer communication network and database technology. Its main functions are to obtain and store positioning information with GPS records, and to collect and store the operation status information of fishing vessels in real time. Pacific saury is one of the important economic species in the North Pacific Ocean, widely distributed in the temperate and subtropical waters of the North Pacific. The main fishing method is the gillnet, which belongs to the floating light trap gillnet. Releasing the net, attracting fish and hauling the net are the three main processes of fishing operations. Pacific saury is a surface water fishing species, with fast swimming speed of fish schools and rapid fishing ground conversion. The large number of vessels makes fishing difficult. Fishing vessels will sail quickly during the process of searching for fish, up to more than 10 knots, and search for fish schools over a large range every day. The prediction of fishing grounds can refer to water temperature, ocean current, etc. Therefore, the prediction of Pacific saury fishing grounds mainly depends on indicators such as water temperature, sea surface height, and vessel position. Due to its special operation mode, the previous research methods for the state of trawling and gillnetting vessels with relatively simple operation modes based on VMS data are not applicable to the Pacific saury fishery. Accurately identifying the real-time state of Pacific saury vessels plays a very important role in the real-time prediction of fishing grounds.

[0003] In summary, a new method is needed to judge the fine operation state (fishing, normal navigation, sheltering from wind, sheltering from waves, drifting) of Pacific saury vessels based on the operation mode of Pacific saury vessels and VMS data. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a method for determining the state of Pacific saury vessels with multiple thresholds mixed judgment.

[0005] The technical solution adopted by the present invention to solve its technical problems is:

[0006] A method for finely determining the state of North Pacific saury vessels with multiple thresholds mixed judgment, which judges the state of each vessel position point through a combination of VMS data, operation time, and marine environment, and can more finely distinguish the vessel state through multiple thresholds mixed judgment. The VMS data is the speed, course difference, and position difference; the operation time is the local time in the North Pacific; the marine environment is the wind and wave data.

[0007] As a preferred embodiment, the states of the saury fishing vessel can be divided into five types: fishing operation I, drifting II, sailing III, sheltering IV, and sheltering V. When the course angle difference (C), the difference in longitude and latitude (l), the speed (v), the operation characteristics (local time (t) in the Northwest Pacific), and the marine environment (wind speed (F), sea waves (W)) are within their respective threshold ranges, it can be considered that the vessel is in the corresponding state.

[0008] The thresholds for the vessel position states are determined as follows:

[0009]

[0010]

[0011]

[0012]

[0013]

[0014] As a preferred embodiment, the vessel can then be in a subdivided stage state. The fishing operation I state can be divided into two stages: A, F, and G. In stage A, which is the fishing operation stage, the speed is maintained between 0.1 and 2 knots, the course difference changes significantly and can reach ±50°, and the time is between 0:00 and 1:00. In stage F, the speed increases, the course difference increases, and the time is at 17:00, which is for accelerating the adjustment of the vessel state and preparing to start the fishing operation. In stage G, the speed is maintained between 0.1 and 2 knots, the course difference changes very significantly and reaches ±60°, and the time is between 18:00 and 24:00, which is the fishing operation stage.

[0015] As a preferred embodiment, the sailing III state can be divided into three stages: B, C, and D. In stage B, the speed increases and the course difference begins to stabilize. The time is around 2:00, which is the end of the previous fishing stage and the stage of accelerating to search for the fishing ground. In stage C, the speed is maintained above 10 knots, and the course difference is stable between ±20°. The time is from 2:00 to 14:00, which is the stage of sailing to transfer to the fishing ground. In stage D, the speed is maintained above 10 knots, and the course difference suddenly increases. The time is around 14:45, which is the stage of discovering the fishing ground.

[0016] As a preferred embodiment, the drifting state II can be divided into stage E. In stage E, the speed is very low, the course difference remains basically unchanged, and the time is around 16:00, which is the drifting stage for searching for fish schools.

[0017] As a preferred embodiment, the unit-time state comparison method is adopted. The ship position state at a certain time can be arbitrarily selected. Taking 30 minutes as a unit time, the ship position states before and after are checked, and at the same time, the differences in longitude and latitude, speed, and course angle between the previous and subsequent states are compared. At the same time, according to the time of the ship's current state, wind speed and sea waves, it is determined which state the ship belongs to.

[0018] As a preferred embodiment, the threshold value of the longitude and latitude difference is obtained according to the position report form of the saury boat in the adjacent 30 minutes and the following discrimination formula:

[0019] L longitude = L moving distance × sin(|C|)

[0020] L latitude = L moving distance × cos(|C|)

[0021] As a preferred embodiment, the threshold value of the ship speed is obtained according to the 24-hour course and speed chart of the saury boat and the annual statistical analysis of multiple ships; the threshold value of the course difference is obtained according to the 24-hour course and speed chart of the saury boat and the annual statistical data analysis of multiple ships. The maximum value of the state course difference is 359°, and the minimum value is -359°.

[0022] As a preferred embodiment, the maximum value of the threshold of the time, which is the local time in the North Pacific, is 24 hours, and the minimum value is 0 hour. As a preferred embodiment, the threshold of the sea waves for the ship to operate safely is below 4m. Generally, the ship will receive a sea wave forecast and avoid it in advance. After the wind and waves, it also needs to return to the fishing ground again before it can start operating. Therefore, the time for two days before and after 4m sea waves is the wave avoidance state.

[0023] Beneficial effects:

[0024] Due to the adoption of the above technical solution, compared with the prior art, the present invention has the following advantages and positive effects: The present invention determines the ship state of the saury boat through multi-threshold mixing. Since the saury boat has a large range of trajectory changes during fishing operations, different from other fishing boats, by mixing multiple thresholds for determination, the ship state can be more finely distinguished. Description of the drawings

[0025] Figure 1 It is the chart of the speed and course change of the Zhanhai 002 ship on May 11, 2021.

[0026] Figure 2 It is the schematic diagram of the ship trajectory of the Zhanhai 002 saury boat on May 11.

[0027] Figure 3 It is the wind and wave value in the wave avoidance state.

[0028] Figure 4 It is the ship position trajectory of the Zhanhai 002 in the wind and wave state.

[0029] Figure 5 It is a schematic diagram of the moving position of a ship under wave shelter conditions. Specific implementation manner

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0031] As Figure 1 shown, a method for extracting the ship state of saury ships from AIS ship position data, the state of each ship position point is judged by combining speed, course difference, moving distance, local time and environmental conditions, and judged by formula (1). When each condition is within different condition threshold ranges, it is judged that the ship is in different states.

[0032] In formula (1), S is the state of the ship position point, its state Ⅰ is the fishing state, state Ⅱ is the drifting state, state Ⅲ is the sailing state, and states (Ⅳ, Ⅴ) are the wave shelter states.

[0033] Subsequently, the ship can be in a subdivided stage state. Stage A is the fishing operation. At this time, the speed is maintained between 0.1 and 2 knots, the course difference changes greatly and can reach ±50°, and the time is between 0:00 and 1:00, which is the fishing operation stage. In stage B, the speed increases, the course difference begins to stabilize, and the time is around 2:00, which is the end of the previous fishing stage and the stage of accelerating to find the fishing ground. In stage C, the speed is maintained above 10 knots, the course difference is stable between ±20°, and the time is from 2:00 to 14:00, which is the stage of sailing to transfer the fishing ground. In stage D, the speed is maintained above 10 knots, the course difference suddenly increases, and the time is around 14:45, which is the stage of discovering the fishing ground. In stage E, the speed is very low, the course difference remains basically unchanged, and the time is around 16:00, which is the drifting stage of looking for fish schools. In stage F, the speed increases and the course difference increases. The time is at 17:00, which is to accelerate the adjustment of the ship state and prepare to start the fishing operation. The speed in stage G is maintained between 0.1 and 2 knots, the course difference changes very greatly and reaches ±60°, and the time is between 18:00 and 24:00, which is the fishing operation stage. In the subdivided stage, stages A and G belong to state Ⅰ, stages B, C, and D are state Ⅱ, and stage F belongs to state Ⅲ. For details, see Figure 2 .

[0034] The position difference of a saury vessel refers to the distance between its previous and current positions within consecutive time units. Combining the position information of multiple vessels, this can be calculated within a thirty-minute interval. At maximum speed, a straight line travels 6.5 minutes in 30 minutes. At 0 knots, the vessel travels 0 minutes in 30 minutes. Therefore, the maximum position difference is 6.5 minutes, and the minimum is 0 minutes.

[0035] The speed of a saury boat refers to the speed at the time of reporting the location. Combining the speed capture values of multiple saury boats throughout the year, it can be concluded that the maximum value is 13 knots and the minimum value is 0 knots.

[0036] A saury boat's heading is the horizontal angle measured clockwise from the north-pointing line at the fishing boat's location to the target heading angle. The heading value ranges from 0 to 360°. When the boat's heading fluctuates around 360° or 0°, the heading value fluctuates significantly. To better determine the fluctuations in the heading angle, the heading angle between adjacent states is calculated to obtain the heading difference. The heading difference here refers to the difference between the headings of two states per unit time. A positive value indicates a clockwise heading change, while a negative value indicates a counterclockwise heading change. A saury boat's heading difference generally does not vary significantly during navigation, but can fluctuate significantly during fishing operations. A year-round analysis of the heading difference values for multiple saury boats reveals a maximum of 359° and a minimum of -359°.

[0037] The time of the saury boat refers to the local operating time. Because the saury boat uses light to lure fish, the operating time is concentrated from 16:00 in the evening to 4:00 in the morning of the next day. In order to facilitate the distinction of its status, we use one day as the discussion interval, set the maximum time to 24:00 local time in the North Pacific, and the minimum time to 0:00 local time in the North Pacific, to facilitate the distinction of its status.

[0038] A simultaneous multi-state test method is used for wind and wave values. In the wind and wave values of a time series every 30 minutes, if the wind and wave value of a point exceeds 4m in multiple time series, then it can be considered that the ship is in a sheltered state two days before and two days after the local time of that point. The judgment formula is as follows.

[0039]

[0040] Among them S n (IV, V) are the states of the ship at multiple points when taking shelter. When the nth point of the wind and wave state of the ship is greater than n-1 points and greater than 4m, it is considered that the ship is in the wave-avoiding state for two days before and after starting from this point.

[0041] Embodiment:

[0042] The present invention will be further described below with a specific embodiment.

[0043] Taking the Zhanhai 002 saury fishing boat on May 11, 2021 as an example for analysis, its state Ⅰ is the fishing state, state Ⅱ is the drifting state, state Ⅲ is the sailing state, and states (Ⅳ, Ⅴ) are the sheltering states. In the sub - phases, phases A and G belong to state Ⅰ, phases B, C, and D are in state Ⅱ, and phase F belongs to state Ⅲ. Phase A is the fishing operation. At this time, the ship speed is maintained between 0.1 - 2 knots, the course difference changes greatly and can reach ±50°, and the time is from 0:00 to 1:00, which is the fishing operation phase. In phase B, the ship speed increases, the course difference begins to stabilize, and the time is around 2:00. This is the end of the previous fishing phase and the stage of accelerating to find the fishing ground. In phase C, the ship speed is maintained above 10 knots, the course difference is stable between ±20°, and the time is from 2:00 to 14:00, which is the stage of sailing to transfer to the fishing ground. In phase D, the ship speed is maintained above 10 knots, the course difference suddenly increases, and the time is around 14:45, which is the stage of discovering the fishing ground. In phase E, the ship speed is very low, the course difference remains basically unchanged, and the time is around 16:00, which is the drifting stage of looking for fish schools. In phase F, the ship speed increases, the course difference increases, and the time is at 17:00, which is the stage of accelerating to adjust the ship state and preparing to start the fishing operation. The ship speed in phase G is maintained between 0.1 - 2 knots, the course difference changes very greatly up to ±60°, and the time is from 18:00 to 24:00, which is the fishing operation stage. The schematic diagram of the ship's movement state is as Figure 3 shown.

[0044] 1. Determine V

[0045] The ship speed of the saury fishing boat refers to the speed at the reporting point. By combining the speed capture values of multiple saury fishing boats throughout the year, its maximum value can be obtained as 13 knots and the minimum value as 0 knots. The ship speed of the Zhanhai 002 ship on May 11, 2021 is as Figure 2 shown.

[0046] 2. Determine C

[0047] The heading of a saury boat refers to the horizontal angle between the north direction line at that point and the target direction angle in a clockwise direction with the fishing boat as the center on the horizontal plane. The heading value is between 0 and 360°. When the heading of the fishing boat changes near 360° or 0°, the heading value will change greatly. In order to better confirm the change in the heading angle, the difference in the heading angles between adjacent states is calculated to obtain the heading difference. The heading difference referred to in this article is the difference between the headings of the latter state and the previous state before and after a unit of time. A positive value reflects a clockwise rotation of the heading, and a negative number reflects a counterclockwise rotation of the heading. The heading difference of a saury boat generally does not change much during navigation, but there will be large changes during fishing operations. Combining the heading differences of multiple saury boats throughout the year, it can be concluded that the maximum value is 359° and the minimum value is -359°. The heading difference of the ship on May 11, 2021 is as follows Figure 2 shown.

[0048] 3. Determine L

[0049] Between any two adjacent states, the distance difference between the two states is expressed as the difference in longitude and latitude. However, since ships usually do not travel in a straight line, the following formula is used to determine L

[0050] They are:

[0051] L 经度 =L 移动距离 ×sin(|C|)

[0052] L 纬度 =L 移动距离 ×cos(|C|)

[0053] In two adjacent states, if L 经度 or L 纬度 If the difference between the two scores does not exceed 1 point, the vessel is considered to be in a drifting or fishing state. If the difference exceeds 1 point, the vessel is considered to be in a sailing state.

[0054] 4. Determine W

[0055] Saury boats can operate safely within a certain range of wave values. When the wind and waves exceed this threshold, the ship will avoid the wind and waves for safety reasons. According to the 2021 North Pacific saury fishing log records and historical wind and wave values, and based on the ship position data, it is judged whether long-distance movement occurs. Combining multiple data, the final W min The wave avoidance period is from August 6 to August 12, 2021. The wind and wave values at that time are as follows: Figure 4 As shown, the ship's moving position under wave avoidance conditions is as follows Figure 5 shown.

[0056] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A method for finely determining the state of ships of Pacific saury in the North Pacific with multi-threshold mixing determination, characterized in that Judge the status of each ship position through the combination of VMS data, operation time, and marine environment. By using a multi-threshold hybrid method to determine the ship status of Pacific saury fishing vessels, the ship status can be more finely differentiated; the VMS data includes speed, course difference, and position difference; the operation time is the local time in the North Pacific; the marine environment is wind and wave data. The ship status of Pacific saury fishing vessels is divided into five types: fishing operation I, drifting II, sailing III, taking shelter IV, and taking shelter V. When the course angle difference C, longitude and latitude difference l, speed v, local time t in the Northwest Pacific, wind speed F, and wave height W are within their respective threshold ranges, it can be considered that the ship is in the corresponding status. The thresholds for ship position status are determined as follows: Subsequently, the ship enters a sub-stage status. The fishing operation I status is divided into two stages: A, F, and G. Stage A is the fishing operation stage. At this time, the speed is maintained between 0.1 and 2 knots, the course difference changes by up to ±50°, and the time is between 0:00 and 1:

00. Stage F is when the speed increases, the course difference increases, and the time is at 17:00, which is for accelerating the adjustment of the ship's status and preparing to start fishing operations. In stage G, the speed is maintained between 0.1 and 2 knots, the course difference changes by ±60°, and the time is between 18:00 and 24:00, which is the fishing operation stage. The sailing III status is divided into three stages: B, C, and D. In stage B, the speed increases and the course difference begins to stabilize. The time is around 2:00, which is the end of the previous fishing stage and the stage of accelerating to find the fishing ground. In stage C, the speed is maintained above 10 knots, and the course difference is stable between ±20°. The time is from 2:00 to 14:00, which is the stage of sailing to transfer the fishing ground. In stage D, the speed is maintained above 10 knots, and the course difference suddenly increases. The time is around 14:45, which is the stage of discovering the fishing ground. The drifting status II is divided into stage E. In stage E, the speed is very low and the course difference remains basically unchanged. The time is around 16:00, which is the drifting stage for searching for fish schools. Adopt the unit-time status comparison method. Arbitrarily select the ship position status at a certain time. Take 30 minutes as a unit time, check the ship position status before and after, and compare the longitude and latitude difference, speed difference, and course angle difference before and after. At the same time, judge the ship's status according to the time, wind speed, and waves in the state where the ship is located. The threshold of the longitude and latitude difference is obtained according to the position report form of the Pacific saury fishing vessel in the adjacent 30 minutes and the following discriminant formula: L longitude = L moving distance × sin(|C|) L latitude = L moving distance × cos(|C|); The threshold of the speed is obtained according to the 24-hour course and speed chart of the Pacific saury fishing vessel and the annual statistical analysis of multiple ships; the threshold of the course difference is obtained according to the maximum value of the course difference in the 24-hour course and speed chart of the Pacific saury fishing vessel and the annual statistical analysis of multiple ships, which is 359°, and the minimum value is -359°.

2. The method for finely determining the state of a ship of Pacific saury in the North Pacific by multi-threshold hybrid determination according to claim 1, wherein The local time in the North Pacific has a maximum threshold of 24 hours and a minimum threshold of 0 hours.

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