System and method for predicting underwater sinking position of wrecked target object

Abstract

The invention discloses a system and a method for predicting the underwater sinking position of a wrecking target object, which belong to the technical field of ship and ocean engineering, are used for predicting the underwater position of the wrecking target object, and comprise a user side and a system computing platform, and the user side communicates with the system computing platform through an ocean communication satellite; the method comprises the following steps: outputting wreck target parameters to a wreck target underwater drop point distribution calculation module, outputting wave flow information of a wreck sea area to the wreck target underwater drop point distribution calculation module, forecasting the sinking drop point distribution of the wreck target, establishing an underwater six-degree-of-freedom motion equation of the wreck target, and calculating the wreck target underwater drop point distribution according to the underwater six-degree-of-freedom motion equation of the wreck target. And according to the underwater six-degree-of-freedom motion equation, predicting underwater drop point distribution of the wrecked target object by combining a Monte Carlo simulation method. Searching can be sequentially carried out according to the falling point scattering probability of the wrecked target object, so that searching resources are reasonably distributed, the success probability of deep sea searching is improved, and the cost of deep sea operation is reduced.

Description

Technical Field

[0001] The invention discloses a system and method for predicting the underwater bottom position of a lost target object, belonging to the technical field of ships and marine engineering. Background Art

[0002] Underwater search for lost targets is like finding a needle in a haystack, which is extremely difficult. On the one hand, deep-sea currents are complex and changeable, making them difficult to predict accurately. On the other hand, the suddenness of marine accidents leads to obvious randomness in the initial position and movement of the crashed target. In addition, the periodic induction of the unsteady tail vortex of the structure has a random effect on its drift posture. Under the coupling of multiple factors, there are many uncertainties in the underwater landing point of the lost target, and its search area often reaches tens or even hundreds of kilometers. If the underwater landing area of ​​the lost target can be accurately predicted, the underwater search will become more targeted, greatly improving the success rate and efficiency of the search. When the target object is lost, it is necessary to calculate and analyze the underwater sinking position of the lost target in combination with the flow field information of the lost sea area, so as to reduce the cost of underwater search operations. At present, underwater detection and search for lost targets mostly rely on previous search experience to determine the final sinking range of the target, so as to carry out large-scale regional searches. Such a search strategy relies too much on past experience and has great uncertainty, resulting in a low success rate in the detection and search of deep-sea lost targets and high costs for deep-sea operations. Summary of the invention

[0003] The purpose of the present invention is to provide a system and method for predicting the underwater bottom position of a lost target object, so as to solve the problem of difficulty in searching for lost targets in the prior art.

[0004] A system for predicting the underwater sinking position of a lost target object comprises a user end and a system computing platform. The user end and the system computing platform communicate with each other via an ocean communication satellite. The user end comprises a user input module and a user output module. The system computing platform comprises a lost target object information monitoring and forecasting module, an ocean information monitoring and forecasting module, a lost target object underwater falling point dispersion calculation module and a result analysis module. The user inputs the crash time and crash location of the crashed object through the user input module, and outputs them to the crashed object information monitoring and forecasting module; The accident target information monitoring and prediction module obtains the accident target parameters, which include the type of the accident target, shape parameters, initial motion speed and initial motion posture, matches the accident target parameters with the accident time and accident location input by the user-side input module, and outputs the accident target parameters, the accident time and the accident location to the underwater drop point dispersion calculation module of the accident target; The ocean information monitoring and forecasting module monitors and forecasts the wave and current information of the sea area where the target object is lost, and provides real ocean environment parameters. The user input module, the lost target information monitoring and forecasting module, and the ocean information monitoring and forecasting module together constitute a virtual underwater scene, and output the wave and current information of the lost sea area to the underwater landing point dispersion calculation module of the lost target; The lost object underwater landing point distribution calculation module predicts the lost object sinking point distribution according to the lost object parameters provided by the virtual underwater scene. The result analysis module provides search strategies to search personnel according to the calculation results of the lost object underwater landing point distribution calculation module, gives the best search strategy among the search strategies according to expert evaluation, and outputs it to the user end. The user end output module presents the expert evaluation results and the best search strategy to the search personnel.

[0005] A method for predicting the underwater sinking position of a crashed target object, using the aforementioned system for predicting the underwater sinking position of a crashed target object, comprising: S1. Randomize the parameters of the crashed object and expand the parameters of the crashed object to The parameters of the crashed object in the three-dimensional random crash position coordinates are selected when calling the crashed object parameters. The data of three-dimensional random crash location coordinates are processed. ; S2, outputting the parameters of the crashed object to the underwater falling point distribution calculation module of the crashed object; S3, outputting the wave and current information of the accident sea area to the underwater falling point distribution calculation module of the accident target object; S4. Predict the distribution of the sinking points of the crashed object, including establishing the underwater 6-DOF motion equation of the crashed object, and predicting the distribution of the underwater landing points of the crashed object based on the underwater 6-DOF motion equation combined with the Monte Carlo simulation method.

[0006] Outputting the parameters of the crashed object to the calculation module of the underwater drop point of the crashed object includes: ; ; ; ; ; ; ; ; ; In the formula, , , It is The crashed object passed through The actual crash location coordinates for time steps, , , It is The crashed object is in The three-dimensional motion displacement within a time step, , , It is The crashed object passed The three-dimensional real-time velocity of time steps, , , It is The crashed object is in The three-dimensional velocity variation within a time step.

[0007] S3 includes S3.1, calculation of wave height, wave phase and roll angle of the wrecked object: ; ; ; In the formula, is the wave height, is the wave phase, is the amplitude, is the wave number, For the wave direction, is the wave frequency, , , is the three-dimensional wavefront position, It's time. is the roll angle of the crashed object.

[0008] S3 includes S3.2, calculation of three-dimensional wave propagation velocity and three-dimensional wave propagation acceleration: ; ; In the formula, , , is the three-dimensional wave propagation speed, , , is the three-dimensional wave propagation acceleration, is the acceleration due to gravity, is a natural constant.

[0009] S3 includes S3.3, calculation of the coupled velocity of three-dimensional wave velocity and ocean current velocity: ; ; In the formula, , , is the coupling velocity of three-dimensional wave velocity and ocean current velocity, , , is the three-dimensional ocean current velocity, is the transformation matrix, , are the pitch angle and yaw angle of the crashed object respectively.

[0010] S3 includes S3.4, calculate the relative speed of the crashed object with respect to the wave current: ; ; ; ; ; ; In the formula, , , is the relative speed of the crashed object relative to the wave flow, , , is the three-dimensional real-time velocity of the crashed object, yes The angular velocity of rotation in the direction yes The angular velocity of rotation in the direction It is along Position variables of the direction, is the length of the crashed object.

[0011] Establishing the underwater 6-DOF motion equations of the crashed object includes establishing the translation equations of the crashed object in three directions: ; ; ; In the formula, is the mass of the crashed object, is the density of water, is the volume of the crashed object, is the acceleration due to gravity, , , is the drag force on the crashed object in three directions, , , For the crashed object , , Three translational additional masses in three directions, , , is the angular velocity in one time step , , The change value of The target of the accident The eccentric coordinates of the direction, The target of the accident The eccentric coordinates of the direction, The target of the accident The eccentric coordinates of the direction, is the vortex induced force, , is the lateral lifting force on the crashed object in two directions, yes The angular velocity of rotation in the direction.

[0012] Establishing the underwater 6-DOF motion equation of the crashed object includes establishing the rotation equations of the crashed object in three directions: ; ; ; ; ; ; In the formula, , , For the crashed object , , Three rotational additional masses in three directions, , , The crashed objects are , , The moment of inertia of the direction, is the kinematic viscosity coefficient of water, is the diameter of the crashed object, , , For the crashed object , , The drag coefficients in three directions, , is the drag torque on the crashed object in two directions, , It is the vertical lifting moment exerted on the crashed object in two directions.

[0013] The crash target , The lateral lifting forces in two directions and the crashed object , The drag torque in two directions and the crash target , The vertical lifting moments in the two directions are: ; ; ; ; ; ; In the formula, To calculate the circulation.

[0014] Compared with the prior art, the present invention provides reasonable search strategies and professional suggestions for underwater detection and search of lost objects. The search can be carried out in sequence according to the probability of the landing points of the lost objects, thereby reasonably allocating search resources, increasing the success rate of deep-sea search, and reducing the cost of deep-sea operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the prediction system of the present invention; Figure 2 is a workflow diagram of the prediction system of the present invention; Figure 3 A technical flow chart for predicting the underwater drop point distribution of a crashed object; Figure 4 The XZ axis prediction model results of the present invention are compared with the water tank test results for working condition 1; Figure 5 The XZ axis prediction model results of the present invention are compared with the water tank test results for working condition 2; Figure 6 This is the overall landing point location diagram for working conditions three and four; Figure 7 This is the local landing point location diagram for working conditions three and four; Figure 8 This is the XZ axis trajectory diagram of the five-dimensional rectangular crash target falling in still water; Fig. 9 The YZ axis trajectory diagram of the five-dimensional rectangular crash target falling in still water; Fig.10 The posture and trajectory of the cuboid crashed object falling in the XZ axis in still water considering the influence of the eccentric moment for working condition 6; Fig.11 The YZ-axis falling posture and trajectory of the rectangular crashed target in still water considering the influence of eccentric moment for working condition 6; Fig.12 The XZ-axis falling posture and falling trajectory of the rectangular crashed target in uniform flow considering the influence of eccentric moment for working condition 7; Fig.13 The YZ-axis falling posture and falling trajectory of the rectangular crashed target in uniform flow considering the influence of eccentric moment for working condition 7; Fig.14 The invention provides a preliminary search strategy based on the probability diagram of the landing point of the cuboid crashed object calculated by the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] A system for predicting the underwater sinking position of a lost target object comprises a user end and a system computing platform. The user end and the system computing platform communicate with each other via an ocean communication satellite. The user end comprises a user input module and a user output module. The system computing platform comprises a lost target object information monitoring and forecasting module, an ocean information monitoring and forecasting module, a lost target object underwater falling point dispersion calculation module and a result analysis module. The user inputs the crash time and crash location of the crashed object through the user input module, and outputs them to the crashed object information monitoring and forecasting module; The accident target information monitoring and prediction module obtains the accident target parameters, which include the type of the accident target, shape parameters, initial motion speed and initial motion posture, matches the accident target parameters with the accident time and accident location input by the user-side input module, and outputs the accident target parameters, the accident time and the accident location to the underwater drop point dispersion calculation module of the accident target; The ocean information monitoring and forecasting module monitors and forecasts the wave and current information of the sea area where the target object is lost, and provides real ocean environment parameters. The user input module, the lost target information monitoring and forecasting module, and the ocean information monitoring and forecasting module together constitute a virtual underwater scene, and output the wave and current information of the lost sea area to the underwater landing point dispersion calculation module of the lost target; The lost object underwater landing point distribution calculation module predicts the lost object sinking point distribution according to the lost object parameters provided by the virtual underwater scene. The result analysis module provides search strategies to search personnel according to the calculation results of the lost object underwater landing point distribution calculation module, gives the best search strategy among the search strategies according to expert evaluation, and outputs it to the user end. The user end output module presents the expert evaluation results and the best search strategy to the search personnel.

[0018] A method for predicting the underwater bottom position of a crashed target object, using the aforementioned system for predicting the underwater bottom position of a crashed target object, comprising: S1. Randomize the parameters of the crashed object and expand the parameters of the crashed object to The parameters of the crashed target object in the three-dimensional random crash position coordinates are selected when calling the crashed target object parameters. The data of three-dimensional random accident location coordinates are processed. ; S2, outputting the parameters of the crashed object to the underwater falling point distribution calculation module of the crashed object; S3, outputting the wave and current information of the accident sea area to the underwater falling point distribution calculation module of the accident target object; S4. Predict the distribution of the sinking points of the crashed object, including establishing the underwater 6-DOF motion equation of the crashed object, and predicting the distribution of the underwater landing points of the crashed object based on the underwater 6-DOF motion equation combined with the Monte Carlo simulation method.

[0019] Outputting the parameters of the crashed object to the calculation module of the underwater drop point of the crashed object includes: ; ; ; ; ; ; ; ; ; In the formula, , , It is The crashed object passed through The actual crash location coordinates for time steps, , , It is The crashed object is in The three-dimensional motion displacement within a time step, , , It is The crashed object passed The three-dimensional real-time velocity of time steps, , , It is The crashed object is in The three-dimensional velocity variation within a time step.

[0020] S3 includes S3.1, calculation of wave height, wave phase and roll angle of the wrecked object: ; ; ; In the formula, is the wave height, is the wave phase, is the amplitude, is the wave number, For the wave direction, is the wave frequency, , , is the three-dimensional wavefront position, It's time. is the roll angle of the crashed object.

[0021] S3 includes S3.2, calculation of three-dimensional wave propagation velocity and three-dimensional wave propagation acceleration: ; ; In the formula, , , is the three-dimensional wave propagation speed, , , is the three-dimensional wave propagation acceleration, is the acceleration due to gravity, is a natural constant.

[0022] S3 includes S3.3, calculation of the coupled velocity of three-dimensional wave velocity and ocean current velocity: ; ; In the formula, , , is the coupling velocity of three-dimensional wave velocity and ocean current velocity, , , is the three-dimensional ocean current velocity, is the transformation matrix, , are the pitch angle and yaw angle of the crashed object respectively.

[0023] S3 includes S3.4, calculate the relative speed of the crashed object with respect to the wave current: ; ; ; ; ; ; In the formula, , , is the relative speed of the crashed object relative to the wave flow, , , is the three-dimensional real-time velocity of the crashed object, yes The angular velocity of rotation in the direction yes The angular velocity of rotation in the direction It is along Position variables of the direction, is the length of the crashed object.

[0024] Establishing the underwater 6-DOF motion equations of the crashed object includes establishing the translation equations of the crashed object in three directions: ; ; ; In the formula, is the mass of the crashed object, is the density of water, is the volume of the crashed object, is the acceleration due to gravity, , , is the drag force on the crashed object in three directions, , , For the crashed object , , Three translational additional masses in three directions, , , is the angular velocity in one time step , , The change value of The target of the accident The eccentric coordinates of the direction, The target of the accident The eccentric coordinates of the direction, The target of the accident The eccentric coordinates of the direction, is the vortex induced force, , is the lateral lifting force on the crashed object in two directions, yes The angular velocity of rotation in the direction.

[0025] Establishing the underwater 6-DOF motion equation of the crashed object includes establishing the rotation equations of the crashed object in three directions: ; ; ; ; ; ; In the formula, , , For the crashed object , , Three rotational additional masses in three directions, , , The crashed objects are , , The moment of inertia of the direction, is the kinematic viscosity coefficient of water, is the diameter of the crashed object, , , For the crashed object , , The drag coefficients in three directions, , is the drag torque on the crashed object in two directions, , It is the vertical lifting moment exerted on the crashed object in two directions.

[0026] The crash target , The lateral lifting forces in two directions and the crashed object , The drag torque in two directions and the crash target , The vertical lifting moments in the two directions are: ; ; ; ; ; ; In the formula, To calculate the circulation.

[0027] The overall structure diagram of the prediction system of the present invention is shown in Figure 1, which includes a user-side input module [1], a crash target information monitoring module [2], an ocean information monitoring module [3], a crash target underwater point distribution calculation module [4], a result analysis module [5] and a user-side output module [6]. The user-side and the system computing platform are connected via an ocean communication satellite. The workflow diagram of the prediction system of the present invention is shown in Figure 1. Figure 2 As shown, the user-side input module [1], the accident target information monitoring module [2], and the ocean information monitoring module [3] together form a virtual underwater scene, which is input into the accident target underwater landing point distribution calculation module [4], and then sequentially input into the result analysis module [5] and the user-side output module [6]. The system of the present invention is based on a mobile terminal, including a tablet computer, a computer, and a mobile electronic device. The system realizes the user-side functions through the above devices, and completes the interaction between the system and the user with the help of the Internet connection.

[0028] The technical flow chart of the prediction of the underwater drop point of the crashed target is as follows: Figure 3As shown, three branches are processed at the beginning. The first branch performs initial situation randomization, and then obtains the initial landing point, initial posture and initial speed for accuracy verification. If it fails the accuracy verification, it returns to the initial situation randomization. If it passes the accuracy verification, random variables are introduced. The second branch performs complex ocean current randomization, and then obtains the current type, current velocity and current direction for accuracy verification. If it fails the accuracy verification, it returns to the complex ocean current randomization. If it passes the accuracy verification, random variables are introduced. The third branch performs nonlinear hydrodynamic randomization, and then the wake vortex induced force, drag coefficient and wake action point are verified for accuracy. If it fails the accuracy verification, it returns to the nonlinear hydrodynamic randomization. If it passes the accuracy verification, random variables are introduced. The three random variables are introduced into the underwater 6-degree-of-freedom motion equation of the crashed target, and the Monte Carlo method is used to predict the landing point distribution.

[0029] The present invention collects seven working conditions, as shown in Table 1.

[0030] Table 1 Working conditions .

[0031] Figure 4 This is a comparison diagram of the predicted results of the present invention and the water tank test results in the XZ axis plane for working condition 1. It can be seen from the figure that the predicted results of the present invention are in good agreement with the test results, and the motion trajectory is basically straight. When the cylinder moves to a depth of about 2.5m, the movement direction of the cylinder changes. The predicted results of the present invention can accurately capture the change in the movement direction, proving the accuracy of the present invention. Figure 5 This is a comparison diagram of the predicted results of the present invention and the water tank test results in the XZ axis plane for working condition 2. It can be seen from the figure that the predicted results of the present invention are in good agreement with the test results, and the motion trajectory is basically straight. When the cylinder moves to a depth of about 2.9m, the movement direction of the cylinder changes. The predicted results of the present invention can accurately capture the change in the movement direction, proving the accuracy of the present invention. Figure 6 The overall drop point scatter diagram calculated by the present invention for working conditions 3 and 4. It can be seen from the figure that for different structures, the underwater drop point position scatter is different. The calculated object for working condition 3 is a cylinder, and its scatter range is large. Its scatter trend spreads from the center position to four directions. The calculated object for working condition 4 is a cuboid, and its scatter range is relatively concentrated. Its scatter trend is similar to that of working condition 3. Differences in parameters such as object type and mass have a more obvious impact on the drop point scatter probability. Figure 7 The locally enlarged landing point scatter diagram calculated by the present invention for working conditions three and four is mainly intended to more clearly analyze the landing point scatter law.

[0032] Figure 8The falling posture and trajectory diagram of the XZ-axis plane calculated by the present invention for working condition five can be clearly seen from the figure that when there is no influence of eccentric moment, the falling trajectory of the rectangular parallelepiped in still water is basically vertical, and the falling posture basically remains horizontal, without obvious posture changes. Fig. 9 The falling posture and trajectory diagram of the YZ-axis plane calculated by the present invention for working condition five can be clearly seen from the figure that when there is no influence of eccentric moment, the falling trajectory of the rectangular parallelepiped in still water is basically vertical, and the falling posture basically remains horizontal, without obvious posture changes. Fig.10 The falling posture and trajectory diagram of the XZ-axis plane calculated by the present invention for working condition six can be clearly seen from the figure that when the influence of the eccentric moment is considered, the falling trajectory of the rectangular parallelepiped in still water no longer remains vertical, and its falling posture will show a large deflection. Fig.11 The falling posture and trajectory diagram of the YZ-axis plane calculated by the present invention for working condition six can be clearly seen from the figure that when the influence of the eccentric moment is considered, the falling trajectory of the rectangular parallelepiped in still water no longer remains vertical, and its falling posture will show a large deflection.

[0033] Fig.12 The falling posture and trajectory diagram of the XZ-axis plane calculated by the present invention for working condition seven can be clearly seen from the figure that when the influence of the eccentric moment is considered, the falling trajectory of the cuboid in the uniform flow is more obvious, and its falling posture will show a larger deflection. Fig.13 The falling posture and trajectory diagram of the YZ axis plane calculated by the present invention for working condition seven can be clearly seen from the figure that when the influence of the eccentric moment is considered, the falling trajectory of the cuboid in the uniform flow is more obvious, and its falling posture will show a large deflection. Fig.14 The present invention provides a search strategy based on the landing point scatter results. The red border area is the area with a high landing point probability, and the yellow border area is the area with a low landing point probability. In actual search, it is necessary to carry out a full coverage search in the red border area, a semi-coverage search in the yellow border area, and a quick search in the remaining areas.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for predicting the underwater sinking position of a crashed object, characterized in that: It includes a user end and a system computing platform. The user end and the system computing platform communicate with each other through an ocean communication satellite. The user end includes a user input module and a user output module. The system computing platform includes a lost target information monitoring and forecasting module, an ocean information monitoring and forecasting module, a lost target underwater drop point distribution calculation module, and a result analysis module. The user inputs the crash time and crash location of the crashed object through the user input module, and outputs them to the crashed object information monitoring and forecasting module; The accident target information monitoring and prediction module obtains the accident target parameters, which include the type of the accident target, shape parameters, initial motion speed and initial motion posture, matches the accident target parameters with the accident time and accident location input by the user-side input module, and outputs the accident target parameters, the accident time and the accident location to the underwater drop point dispersion calculation module of the accident target; The ocean information monitoring and forecasting module monitors and forecasts the wave and current information of the sea area where the target object is lost, and provides real ocean environment parameters. The user input module, the lost target information monitoring and forecasting module, and the ocean information monitoring and forecasting module together constitute a virtual underwater scene, and output the wave and current information of the lost sea area to the underwater landing point dispersion calculation module of the lost target; The lost object underwater landing point distribution calculation module predicts the lost object sinking point distribution according to the lost object parameters provided by the virtual underwater scene. The result analysis module provides search strategies to search personnel according to the calculation results of the lost object underwater landing point distribution calculation module, gives the best search strategy among the search strategies according to expert evaluation, and outputs it to the user end. The user end output module presents the expert evaluation results and the best search strategy to the search personnel.

2. A method for predicting the underwater bottom position of a lost target object, using the underwater bottom position prediction system of a lost target object according to claim 1, characterized in that: include: S1. Randomize the parameters of the crashed object and expand the parameters of the crashed object to The parameters of the crashed object in the three-dimensional random crash position coordinates are selected when calling the crashed object parameters. The data of three-dimensional random crash location coordinates are processed. ; S2, outputting the parameters of the crashed object to the underwater falling point distribution calculation module of the crashed object; S3, outputting the wave and current information of the accident sea area to the underwater falling point distribution calculation module of the accident target object; S4. Predict the distribution of the sinking points of the crashed object, including establishing the underwater 6-DOF motion equation of the crashed object, and predicting the distribution of the underwater landing points of the crashed object based on the underwater 6-DOF motion equation combined with the Monte Carlo simulation method.

3. A method for predicting the underwater sinking position of a crashed object according to claim 2, characterized in that: Outputting the parameters of the crashed object to the calculation module of the underwater drop point of the crashed object includes: ； ； ； ； ； ； ； ； ； In the formula, , , It is The crashed object passed through The actual crash location coordinates for time steps, , , It is The crashed object is in The three-dimensional motion displacement within a time step, , , It is The crashed object passed The three-dimensional real-time velocity of time steps, , , It is The crashed object is in The three-dimensional velocity variation within a time step.

4. A method for predicting the underwater sinking position of a crashed object according to claim 3, characterized in that: S3 includes S3.1, calculation of wave height, wave phase and roll angle of the wrecked object: ； ； ； In the formula, is the wave height, is the wave phase, is the amplitude, is the wave number, For the wave direction, is the wave frequency, , , is the three-dimensional wavefront position, It's time. is the roll angle of the crashed object.

5. A method for predicting the underwater sinking position of a crashed object according to claim 4, characterized in that: S3 includes S3.2, calculation of three-dimensional wave propagation velocity and three-dimensional wave propagation acceleration: ； ； In the formula, , , is the three-dimensional wave propagation speed, , , is the three-dimensional wave propagation acceleration, is the acceleration due to gravity, is a natural constant.

6. A method for predicting the underwater bottom position of a crashed object according to claim 5, characterized in that: S3 includes S3.3, calculation of the coupled velocity of three-dimensional wave velocity and ocean current velocity: ； ； In the formula, , , is the coupling velocity of three-dimensional wave velocity and ocean current velocity, , , is the three-dimensional ocean current velocity, is the transformation matrix, , are the pitch angle and yaw angle of the crashed object respectively.

7. A method for predicting the underwater bottom position of a crashed object according to claim 6, characterized in that: S3 includes S3.4, calculate the relative speed of the crashed object with respect to the wave current: ； ； ； ； ； ； In the formula, , , is the relative speed of the crashed object relative to the wave flow, , , is the three-dimensional real-time velocity of the crashed object, yes The angular velocity of rotation in the direction yes The angular velocity of rotation in the direction It is along Position variables of the direction, is the length of the crashed object.

8. A method for predicting the underwater bottom position of a crashed object according to claim 7, characterized in that: Establishing the underwater 6-DOF motion equations of the crashed object includes establishing the translation equations of the crashed object in three directions: ； ； ； In the formula, is the mass of the crashed object, is the density of water, is the volume of the crashed object, is the acceleration due to gravity, , , is the drag force on the crashed object in three directions, , , For the crashed object , , Three translational additional masses in three directions, , , is the angular velocity in one time step , , The change value of The target of the accident The eccentric coordinates of the direction, The target of the accident The eccentric coordinates of the direction, The target of the accident The eccentric coordinates of the direction, is the vortex induced force, , is the lateral lifting force on the crashed object in two directions, yes The angular velocity of rotation in the direction.

9. A method for predicting the underwater sinking position of a crashed object according to claim 8, characterized in that: Establishing the underwater 6-DOF motion equation of the crashed object includes establishing the rotation equations of the crashed object in three directions: ； ； ； ； ； ； In the formula, , , For the crashed object , , Three rotational additional masses in three directions, , , The crashed objects are , , The moment of inertia of the direction, is the kinematic viscosity coefficient of water, is the diameter of the crashed object, , , For the crashed object , , The drag coefficients in three directions, , is the drag torque on the crashed object in two directions, , It is the vertical lifting moment exerted on the crashed object in two directions.

10. A method for predicting the underwater bottom position of a crashed object according to claim 9, characterized in that: The crash target , The lateral lifting forces in two directions and the crashed object , The drag torque in two directions and the crash target , The vertical lifting moments in the two directions are: ； ； ； ； ； ； In the formula, To calculate the circulation.

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