BeiDou-3 based ship navigation monitoring and early warning method, system and computer-readable storage medium

Abstract

The present application relates to the field of ship navigation monitoring and control technology, and specifically to a ship navigation monitoring and early warning method, system and computer-readable storage medium based on Beidou-3, the method comprising: collecting various environmental parameter data at each moment when the ship is sailing; determining abnormal moments and change moments among all collected moments; determining the environmental impact index at each moment based on the distribution of abnormal moments and change moments, and the difference between the environmental parameter data at the change moment and its average level; analyzing the difference between the local minimum value and its adjacent maximum value in the environmental parameter data at all moments before each moment, combining the time interval between the adjacent maximum values ​​and the environmental impact index, to obtain the flight change risk index at each moment; adjusting the control parameters in the PID controller in real time based on the flight change risk index, and monitoring and early warning the ship's navigation. Thereby improving the accuracy of ship navigation control.

Description

Technical Field

[0001] The present application relates to the field of ship navigation monitoring and control technology, and specifically to a ship navigation monitoring and early warning method, system and computer-readable storage medium based on BeiDou-3. Background Art

[0002] Ship navigation monitoring refers to real-time monitoring of the ship's position, speed, heading and other information, and the assessment and early warning of potential risks. Ship navigation monitoring can detect and warn of possible risks such as collisions and groundings in advance, providing the crew with enough time to take risk avoidance measures. Environmental factors have many impacts on ship navigation, including but not limited to wind speed, wind direction, ocean currents, etc. These factors may have a significant impact on the stability, speed and route selection of the ship.

[0003] Existing ship navigation monitoring focuses on navigation safety and lacks comprehensive monitoring of marine environmental factors. In the process of using PID controller to monitor and control ship navigation, the conventional initialization sets the control parameters of the PID controller, which affects the monitoring and control accuracy of ship navigation, resulting in low accuracy of ship navigation monitoring and early warning. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a ship navigation monitoring and early warning method, system and computer-readable storage medium based on BeiDou-3. The technical solutions adopted are as follows:

[0005] In a first aspect, an embodiment of the present application provides a ship navigation monitoring and early warning method based on BeiDou-3, the method comprising the following steps:

[0006] Collect various environmental parameter data at all times when the ship is sailing;

[0007] Analyze the abnormal conditions and fluctuations of the environmental parameter data at all times before each moment, and determine the abnormal moments and change moments among all the collected moments; determine the environmental impact index at each moment based on the distribution of the abnormal moments and change moments, and the difference between the environmental parameter data at the change moment and its average level;

[0008] Analyze the difference between the local minimum value and the adjacent maximum value in the environmental parameter data of all moments before each moment, and combine the time interval between the adjacent maximum values ​​with the environmental impact index to obtain the flight change risk index at each moment;

[0009] Based on the flight change risk index, the control parameters in the PID controller are adjusted in real time to monitor and warn the ship's navigation.

[0010] In one embodiment, the environmental parameter data includes wind speed and direction, and speed and direction of ocean currents.

[0011] In one embodiment, the process of determining the abnormal moment is:

[0012] For each type of environmental parameter data, the data of all moments before each moment are combined into a time series, and an anomaly detection algorithm is used to obtain each abnormal value in the time series, and the moment corresponding to the abnormal value is recorded as the abnormal moment.

[0013] In one embodiment, the process of determining the change time is:

[0014] Each extreme value in the time series is detected, and the time corresponding to the extreme value is recorded as the change time.

[0015] In one embodiment, the process of determining the environmental impact index is as follows:

[0016] For any type of environmental parameter data, calculate the discreteness of all abnormal moments and change moments, calculate the mean of all elements in the corresponding time series, and calculate the average value of the difference between the elements corresponding to all change moments in any type of environmental parameter data and the mean;

[0017] The environmental impact index is proportional to the average value of all types of environmental parameter data, and inversely proportional to the degree of dispersion of all types of environmental parameter data.

[0018] In one embodiment, the process of determining the flight change risk index is as follows:

[0019] The wind directions at all times before each moment are combined into a wind direction sequence, and the directions of the ocean currents at all times before each moment are combined into an ocean current direction sequence;

[0020] For the wind direction sequence, a sliding window is preset, and the maximum value of the difference between each minimum value in each sliding window and its left and right adjacent maximum values ​​is calculated, and the time difference between the left and right adjacent maximum values ​​is calculated to obtain the ratio of the maximum value to the time difference. The sum of the ratios of all the minimum values ​​in each sliding window is recorded as a first sum value, the cumulative sum of the first sum values ​​in all sliding windows is recorded as a second sum value, and the product of the environmental impact index at each moment and the second sum value is recorded as a first flight change risk index;

[0021] For the ocean current direction sequence, the second flight change risk index is obtained by using the same calculation method as the first flight change risk index for the wind direction sequence;

[0022] The maximum value of the first flight change risk index and the second flight change risk index at each moment is recorded as the flight change risk index at each moment.

[0023] In one embodiment, the real-time adjustment of control parameters in the PID controller based on the flight change risk index includes:

[0024] An adjustment function is constructed based on the flight change risk index at each moment, and the product of the initial proportional parameter of the PID controller and the adjustment function is used as the adjusted proportional parameter of the PID controller.

[0025] In one embodiment, the adjustment function is calculated as follows: ;

[0026] In the formula, is the adjustment function at each moment, is the flight change risk index at each moment, Norm() is the normalization function, is the first preset value, is the second preset value, wherein, and Both are greater than 0 and less than 1.

[0027] In the second aspect, the embodiment of the present application also provides a ship navigation monitoring and early warning system based on BeiDou-3, including:

[0028] Environmental parameter collection module: used to collect various environmental parameter data at all times during the ship's voyage;

[0029] Environmental impact analysis module: used to analyze the abnormal conditions and fluctuations of environmental parameter data at all times before each moment, and determine the abnormal moments and change moments among all collected moments; based on the distribution of abnormal moments and change moments, and the difference between the environmental parameter data at the change moment and its average level, determine the environmental impact index at each moment;

[0030] Flight change risk assessment module: used to analyze the difference between the local minimum value and the adjacent maximum value in the environmental parameter data of all moments before each moment, and combine the time interval between the adjacent maximum values ​​with the environmental impact index to obtain the flight change risk index at each moment;

[0031] Navigation warning control module: based on the navigation change risk index, the control parameters in the PID controller are adjusted in real time to monitor and warn the ship's navigation.

[0032] In a third aspect, an embodiment of the present application further provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps of any one of the above methods are implemented.

[0033] This application has at least the following beneficial effects:

[0034] The present application collects various environmental parameter data at each moment of the ship's voyage; analyzes the abnormal conditions and fluctuations of the environmental parameter data at all moments before each moment, and determines the abnormal moments and change moments among all the collected moments; by identifying the abnormal moments in the ship's voyage, it is helpful to accurately extract the abnormal characteristics of the ship's voyage in the subsequent process; based on the distribution of abnormal moments and change moments, and the difference between the environmental parameter data at the change moment and its average level, the environmental impact index at each moment is determined; the environmental impact index reflects the degree of fluctuation and deviation of the environmental parameter data at the abnormal moment and the change moment. The higher the environmental impact index, the greater the deviation of the environmental parameter at the change moment relative to the overall fluctuation, the more consistent the change trend of the environmental parameter, the greater the impact on the route, and the accuracy of the route deviation analysis is improved; further , analyze the difference between the local minimum value and the adjacent maximum value in the environmental parameter data of all moments before each moment, combine the time interval between the adjacent maximum values ​​and the environmental impact index, and obtain the flight change risk index at each moment; the flight change risk index comprehensively measures the potential impact of environmental parameter changes on the ship's navigation route in a local time period, and reflects the potential risk of environmental parameter changes on the ship's route in real-time navigation monitoring. The higher the flight change risk index, the greater the impact of environmental parameter changes on the ship's navigation route, and the higher the possibility of risk in ship navigation, which improves the accuracy of ship navigation monitoring and early warning; based on the flight change risk index, the control parameters in the PID controller are adjusted in real time to monitor and warn of ship navigation; the environmental parameter data during the ship's navigation process is comprehensively considered to improve the accuracy of ship navigation monitoring and control. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A flowchart of a BeiDou-3-based ship navigation monitoring and early warning method provided in one embodiment of the present application;

[0037] Figure 2 Flowchart for PID controller proportional parameter adjustment. DETAILED DESCRIPTION

[0038] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following, in combination with the accompanying drawings and preferred embodiments, describes in detail the specific implementation methods, structures, features and effects of the BeiDou-3-based ship navigation monitoring and early warning method, system and computer-readable storage medium proposed in the present application. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0039] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0040] The specific scheme of the BeiDou-3 based ship navigation monitoring and early warning method, system and computer-readable storage medium provided in this application is described in detail below with reference to the accompanying drawings.

[0041] See also Figure 1 , which shows a flowchart of a method for monitoring and early warning of ship navigation based on BeiDou-3 provided by an embodiment of the present application, the method comprising the following steps:

[0042] S1, collects various environmental parameter data at all times when the ship is sailing.

[0043] In this embodiment, an acoustic Doppler current profiler (ADCP) is installed on the bottom of the ship to measure the speed and direction of the ocean current at each moment; secondly, an ultrasonic anemometer is installed on the mast of the ship to monitor the wind speed and wind direction at each moment when the ship is sailing in real time. The speed and direction, the wind speed and wind direction are recorded as environmental parameter data.

[0044] For the wind speed and the ocean current rate, the acquisition frequency in this embodiment is 20HZ, which can be set by the implementer according to the actual situation, and this embodiment does not limit it; the ocean current rate at each moment corresponds to a direction, and the wind speed at each moment also corresponds to a direction. For the wind direction and the direction of the ocean current, this embodiment takes the north direction as the starting point, and the degrees of clockwise rotation range from 0° to 360°.

[0045] To facilitate the subsequent unified analysis and calculation, the speed and direction, wind speed and wind direction collected at all times are normalized using the maximum-minimum normalization method. The normalized current speeds at all times before each moment are combined into a current speed sequence, the normalized current directions at all times before each moment are combined into a current direction sequence, the normalized wind speeds at all times before each moment are combined into a wind speed sequence, and the normalized wind directions at all times before each moment are combined into a wind direction sequence.

[0046] It should be noted that the maximum-minimum normalization method is an existing well-known technology, and the implementer can choose other existing feasible normalization methods, such as Z-score normalization, logarithmic normalization, etc., which is not limited in this embodiment.

[0047] S2, analyze the abnormal conditions and fluctuation degree of the environmental parameter data at all moments before each moment, and determine the abnormal moments and change moments among all the collected moments; based on the distribution of the abnormal moments and the change moments, and the difference between the environmental parameter data at the change moment and its average level, determine the environmental impact index at each moment.

[0048] During the ship's route planning stage, the real-time position information of the ship is first obtained through the BeiDou-3 satellite navigation system, and an optimal route is calculated using the professional route planning software MaxSea TimeZero. This route will take into account avoiding navigation obstacles, shoals and bad weather areas, while also considering the ship's performance parameters, such as draft and maneuverability, to ensure the feasibility of the route. The specific route planning is a technology well known to people in this field and will not be elaborated here.

[0049] After determining the optimal route, the coordinates of the points on the route need to be sent to the ship in the form of short messages. This process is based on the Beidou protocol. At the same time, in order to ensure that the ship is always under monitoring, the ship needs to regularly report its own positioning information to the shore-based monitoring platform in the form of short messages. This positioning information includes the ship's real-time position, speed, and heading, which are sent through the Beidou-3 satellite navigation system.

[0050] During the navigation process of a ship, environmental factors have a significant impact on the choice of navigation route and the speed of the ship. The speed and direction of the ocean current can change the actual course and speed of the ship. Changes in the direction of the ocean current may force the ship to adjust its route to avoid deviating from the intended course. Wind speed and direction are equally important. Strong headwinds will increase navigation resistance and reduce speed, while tailwinds will help increase speed. In addition, crosswinds may affect the stability of the ship, requiring the crew to adjust the course to maintain stability.

[0051] Therefore, it is necessary to analyze the changing rules of the collected environmental parameter data. Taking the ocean current rate sequence at each moment as an example, the ocean current rate sequence is used as the input of the LOF (Local Outlier Factor) anomaly detection algorithm, and the output is the abnormal values ​​in the ocean current rate sequence. The collection time corresponding to each abnormal value is recorded as the abnormal time. Secondly, the ocean current rate sequence is subjected to the extreme value detection algorithm to obtain the extreme values ​​in the ocean current rate sequence, including the maximum value and the minimum value, and the collection time corresponding to each extreme value is recorded as the change time.

[0052] In this embodiment, the number of adjacent points set by the LOF anomaly detection algorithm is 10, and the ratio of anomaly points is 0.1. The implementer can set them according to the actual situation. The LOF anomaly detection algorithm is an existing public technology and will not be described in detail here. The implementer can choose other existing feasible anomaly detection algorithms according to the actual situation.

[0053] For the ocean current direction sequence, wind speed sequence, and wind direction sequence, the same method as that for the ocean current velocity sequence is used to obtain the abnormal moment and change moment, and the abnormal moment and change moment of the ocean current direction sequence, wind speed sequence, and wind direction sequence are obtained respectively.

[0054] Similarly, the ocean current rate sequence at each moment is used as an example for analysis, the discreteness of all abnormal moments and change moments in the ocean current rate sequence is calculated, the mean of all elements in the ocean current rate sequence is calculated, and the average value of the difference between the elements corresponding to all change moments in the ocean current rate sequence and the mean is calculated, which is recorded as the change mean;

[0055] It should be noted that the degree of dispersion can be calculated by variance, standard deviation, coefficient of variation, etc. This embodiment uses standard deviation as the method for calculating the degree of dispersion. The difference can be calculated by the absolute value of the difference, the square of the difference, the ratio, etc. This embodiment uses the absolute value of the difference as the method for calculating the difference.

[0056] In this embodiment, for the ocean current rate sequence at each moment, the product of the standard deviation of all abnormal moments and the standard deviation of all change moments is calculated, and the environmental impact index at each moment is determined by combining the product with the change mean. The specific calculation method is: ;

[0057] A is the environmental impact index at each moment, is the mean value of the change corresponding to the i-th sequence, is the product of the standard deviation of all abnormal moments corresponding to the i-th sequence and the standard deviation of all change moments, and M is the number of sequences analyzed in this embodiment, including ocean current direction sequence, wind speed sequence, wind direction sequence, and ocean current velocity sequence. Therefore, in this embodiment, M=4.

[0058] It should be understood that It reflects the joint characteristics of the fluctuation of environmental parameter data of the i-th sequence at abnormal and changing moments. The larger the value, the more dispersed the fluctuation of environmental parameter data at abnormal moments and change moments. This dispersion indicates that the changes of environmental parameters at these critical moments are multi-directional and multi-amplitude. The less concentrated the environmental changes encountered during navigation, the more inconsistent the environmental change trends, and the less likely it is to affect the route. Therefore, the smaller the value of the environmental impact index A is; It reflects the degree of change of environmental parameter data relative to its average level at the time of change. The larger the value is, the greater the deviation of the environmental parameters at the time of change, the greater the degree of change in the environment, and the larger the value of the environmental impact index A.

[0059] The higher the environmental impact index is, the more consistent the trend of environmental change is, and the greater the deviation of environmental parameters at the moment of change is relative to the overall fluctuation, making the navigation route more prone to potential deviation risks.

[0060] S3, analyzing the difference between the local minimum value and the adjacent maximum value in the environmental parameter data of all moments before each moment, combining the time interval between the adjacent maximum values ​​and the environmental impact index, to obtain the flight change risk index at each moment.

[0061] In the above analysis, the concentrated influence of wind direction and current direction on the ship's route is mainly analyzed. However, in ship navigation monitoring, in addition to considering the long-term concentrated influence of wind direction and current direction on the overall route of the ship, the local influence of environmental factors on the hull in different directions in a short period of time is also crucial. Local changes in wind direction and flow direction can cause uneven force on the hull, thereby causing a deviation in heading. Although this deviation may not be obvious in a short period of time, the cumulative effect may cause the ship to deviate significantly from the scheduled route.

[0062] Therefore, for the wind direction sequence and the ocean current direction sequence at each moment, a sliding window is set respectively. In this embodiment, the length of the sliding window is 1200, and the implementer can set it according to the actual situation. This embodiment does not limit it. Taking the wind direction sequence as an example, the first element in the wind direction sequence is used as the first element of the initial position of the sliding window, that is, the initial position of the sliding window contains the first 1200 elements in the wind direction sequence, and slides to the right with a step length of 20 until the last element in the sliding window is the last data in the wind direction sequence, thereby obtaining each sliding window in the wind direction sequence. For the ocean current direction sequence, the same method as the wind direction sequence is used to obtain each sliding window in the ocean current direction sequence.

[0063] Secondly, the elements in each sliding window are used as input, and the extreme point detection algorithm is used to output all extreme points in each sliding window. Extreme points include maximum values ​​and minimum values. For any minimum value, the maximum value of the difference between each minimum value and its left and right adjacent maximum values ​​is calculated. It should be noted that if the minimum point has only a left adjacent maximum value, or only a right adjacent maximum value, it and the adjacent maximum value on the other side are recorded as 0. Among them, extreme point detection is a common technology in the field of data processing, and the specific process will not be repeated.

[0064] Taking the wind direction sequence at each moment as an example, the corresponding first flight change risk index is calculated. The specific calculation method is: ;

[0065] Where B is the first flight change risk index corresponding to the wind direction sequence at each moment, is the maximum value of the difference between the nth minimum value in the i-th sliding window and its left and right adjacent maximum values, T is the time interval between the left and right adjacent maximum values ​​of the nth minimum value in the i-th sliding window, [ ] is the rounding function, N is the number of minimum values ​​in the i-th sliding window, K is the number of sliding windows in the wind direction sequence at each moment, and A is the environmental impact index at each moment. Denoted as the first sum, Recorded as the second sum.

[0066] For the ocean current direction sequence at each moment, the same calculation method as the first flight change risk index is adopted to obtain the second flight change risk index corresponding to the ocean current direction sequence at each moment.

[0067] At each moment, the maximum value of the first flight change risk index and the second flight change risk index is used as the flight change risk index at each moment.

[0068] It should be understood that the environmental impact index reflects the degree of fluctuation and deviation of environmental parameter data at abnormal moments and changing moments. The higher the environmental impact index, the greater the deviation of the environmental parameters at the moment of change relative to the overall fluctuation, the more consistent the changing trend of the environmental parameters, the greater the impact on the route, and the greater the flight change risk index; it indicates the severity of changes in wind direction or current direction within a local time period. The larger the value, the more severe the change in wind direction or current direction within the sliding window, and the greater the directional deviation in a short period of time. At this time, the hull is more likely to be subjected to uneven force, and the greater the flight change risk index.

[0069] The flight change risk index comprehensively measures the potential impact of changes in environmental parameters on the ship's navigation route within a local time period, and reflects the potential risk of changes in environmental parameters to the ship's navigation route in real-time navigation monitoring. The higher the flight change risk index, the greater the impact of changes in environmental parameters on the ship's navigation route, and the need to adjust the route or take other measures to cope with these changes to ensure navigation safety and efficiency.

[0070] S4, adjusting the control parameters in the PID controller in real time based on the flight change risk index, and providing navigation monitoring and early warning for the ship.

[0071] This embodiment uses a PID controller to monitor and control the navigation of the ship. The PID controller consists of three parts: proportional (P), integral (I) and differential (D). The control of the ship's navigation is achieved by adjusting these three parameters, and the ship's rudder angle is adjusted to maintain the stability of the ship's heading. The proportional (P) parameter can immediately respond to the current heading deviation and output a control signal proportional to the deviation to reduce the deviation. The integral (I) parameter accumulates the deviation and generates a control signal proportional to the accumulated deviation, which helps to eliminate steady-state errors. The differential (D) parameter predicts the rate of change of the deviation and outputs a control signal proportional to the rate of change of the deviation, thereby reducing overshoot and oscillation. Since the proportional (P) parameter directly affects the response speed and steady-state performance of the ship's navigation control, this embodiment adjusts the proportional (P) parameter in real time in combination with the flight change risk index at each moment.

[0072] The specific adjustment relationship is: ,in, is the adjusted proportional parameter, P is the initial proportional parameter, is the adjustment function, and in this embodiment, ; In the formula, is the adjustment function at each moment, is the flight change risk index at each moment, Norm() is the normalization function, is the first preset value, is the second preset value, wherein, and All are greater than 0 and less than 1; in this embodiment , , the implementer can set it according to the actual situation, and this embodiment does not limit it here; by adjusting the function to map the value range of B, the value range of B is mapped to 0.75~1.25, and then The initial scale parameter is weighted to adjust the Control arrive To avoid overshoot oscillation caused by excessive proportional parameters or slow response speed caused by too small proportional parameters. Figure 2 shown.

[0073] It should be noted that in this embodiment, the initial proportional (P) parameter is set to 100, the initial integral (I) is set to 0.15, and the initial differential (D) parameter is set to 9000. During the process of the PID controller monitoring and controlling the ship's navigation, the integral (I) parameter and the differential (D) parameter remain unchanged at the initial values.

[0074] Through the above adjustment, when the risk index of flight change is larger, that is, the risk of flight change is larger, the P parameter is increased to quickly respond to environmental changes. At this time, the response speed of the PID controller is improved through the P parameter, so that the PID controller can respond faster and output control signals when the route deviates, and control the ship's rudder angle in time to avoid the impact of route deviation; vice versa. By dynamically adjusting the P parameter of the PID controller according to the risk index of flight change, it can adapt to different sea conditions and operating conditions more flexibly, thereby improving the response speed and stability of the ship's heading control and ensuring navigation safety and efficiency.

[0075] The embodiment of the present application also provides a ship navigation monitoring and early warning system based on BeiDou-3, including:

[0076] Environmental parameter collection module: used to collect various environmental parameter data at all times during the ship's voyage;

[0077] Environmental impact analysis module: used to analyze the abnormal conditions and fluctuations of environmental parameter data at all times before each moment, and determine the abnormal moments and change moments among all collected moments; based on the distribution of abnormal moments and change moments, and the difference between the environmental parameter data at the change moment and its average level, determine the environmental impact index at each moment;

[0078] Flight change risk assessment module: used to analyze the difference between the local minimum value and the adjacent maximum value in the environmental parameter data of all moments before each moment, and combine the time interval between the adjacent maximum values ​​with the environmental impact index to obtain the flight change risk index at each moment;

[0079] Navigation warning control module: based on the navigation change risk index, the control parameters in the PID controller are adjusted in real time to monitor and warn the ship's navigation.

[0080] Based on the same inventive concept as the above method, an embodiment of the present application also provides a computer-readable storage medium for ship navigation monitoring and early warning based on Beidou-3, on which a computer program is stored. When the computer program is executed by a processor, the steps of any one of the above-mentioned methods for ship navigation monitoring and early warning based on Beidou-3 are implemented.

[0081] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0082] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0083] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A ship navigation monitoring and early warning method based on BeiDou-3 is characterized in that: The method comprises the following steps: Collect various environmental parameter data at all times when the ship is sailing; Analyze the abnormal conditions and fluctuations of the environmental parameter data at all times before each moment, and determine the abnormal moments and change moments among all the collected moments; determine the environmental impact index at each moment based on the distribution of the abnormal moments and change moments, and the difference between the environmental parameter data at the change moment and its average level; Analyze the difference between the local minimum value and the adjacent maximum value in the environmental parameter data of all moments before each moment, and combine the time interval between the adjacent maximum values ​​with the environmental impact index to obtain the flight change risk index at each moment; Based on the flight change risk index, the control parameters in the PID controller are adjusted in real time to monitor and warn the ship's navigation.

2. The BeiDou-3-based ship navigation monitoring and early warning method according to claim 1, characterized in that: The environmental parameter data include wind speed and direction, and speed and direction of ocean currents.

3. The BeiDou-3-based ship navigation monitoring and early warning method according to claim 1, characterized in that: The process of determining the abnormal moment is as follows: For each type of environmental parameter data, the data of all moments before each moment are combined into a time series, and an anomaly detection algorithm is used to obtain each abnormal value in the time series, and the moment corresponding to the abnormal value is recorded as the abnormal moment.

4. The BeiDou-3-based ship navigation monitoring and early warning method according to claim 3, characterized in that: The process of determining the change moment is as follows: Each extreme value in the time series is detected, and the time corresponding to the extreme value is recorded as the change time.

5. The BeiDou-3-based ship navigation monitoring and early warning method as claimed in claim 3, characterized in that: The process of determining the environmental impact index is as follows: For any type of environmental parameter data, calculate the discreteness of all abnormal moments and change moments, calculate the mean of all elements in the corresponding time series, and calculate the average value of the difference between the elements corresponding to all change moments in any type of environmental parameter data and the mean; The environmental impact index is proportional to the average value of all types of environmental parameter data, and inversely proportional to the degree of dispersion of all types of environmental parameter data.

6. The BeiDou-3-based ship navigation monitoring and early warning method according to claim 2, characterized in that: The process of determining the flight change risk index is as follows: The wind directions at all times before each moment are combined into a wind direction sequence, and the directions of the ocean currents at all times before each moment are combined into an ocean current direction sequence; For the wind direction sequence, a sliding window is preset, and the maximum value of the difference between each minimum value in each sliding window and its left and right adjacent maximum values ​​is calculated, and the time difference between the left and right adjacent maximum values ​​is calculated to obtain the ratio of the maximum value to the time difference. The sum of the ratios of all the minimum values ​​in each sliding window is recorded as a first sum value, the cumulative sum of the first sum values ​​in all sliding windows is recorded as a second sum value, and the product of the environmental impact index at each moment and the second sum value is recorded as a first flight change risk index; For the ocean current direction sequence, the second flight change risk index is obtained by using the same calculation method as the first flight change risk index for the wind direction sequence; The maximum value of the first flight change risk index and the second flight change risk index at each moment is recorded as the flight change risk index at each moment.

7. The BeiDou-3-based ship navigation monitoring and early warning method according to claim 1, characterized in that: The real-time adjustment of control parameters in the PID controller based on the flight change risk index includes: An adjustment function is constructed based on the flight change risk index at each moment, and the product of the initial proportional parameter of the PID controller and the adjustment function is used as the adjusted proportional parameter of the PID controller.

8. The BeiDou-3-based ship navigation monitoring and early warning method according to claim 7, characterized in that: The adjustment function is calculated as follows: ; In the formula, is the adjustment function at each moment, is the flight change risk index at each moment, Norm() is the normalization function, is the first preset value, is the second preset value, wherein, and Both are greater than 0 and less than 1.

9. The BeiDou-3-based ship navigation monitoring and early warning system is characterized by: include: Environmental parameter collection module: used to collect various environmental parameter data at all times during the ship's voyage; Environmental impact analysis module: used to analyze the abnormal conditions and fluctuations of environmental parameter data at all times before each moment, and determine the abnormal moments and change moments among all collected moments; based on the distribution of abnormal moments and change moments, and the difference between the environmental parameter data at the change moment and its average level, determine the environmental impact index at each moment; Flight change risk assessment module: used to analyze the difference between the local minimum value and the adjacent maximum value in the environmental parameter data of all moments before each moment, and combine the time interval between the adjacent maximum values ​​with the environmental impact index to obtain the flight change risk index at each moment; Navigation warning control module: based on the navigation change risk index, the control parameters in the PID controller are adjusted in real time to monitor and warn the ship's navigation.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the corresponding steps involved in the method according to any one of claims 1 to 8 are implemented.

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