Construction method of virtual-real twin model of ship ladder and cable coupling under the action of sea wave interference

Abstract

This application relates to the field of virtual-real twin technology, specifically to a method for constructing a virtual-real twin model of a ship ladder and cable coupling under the interference of ocean waves. The method includes: obtaining the attitude images of the ship ladder and cable at each moment during their movement, and obtaining the stress data of each cable segment on the ship ladder and cable at each moment; determining the curvature of each cable segment at each moment; calculating the potential bending weight value of each cable segment at each moment; obtaining the coupling eigenvalue of each cable segment at each moment; obtaining the fault risk value of the ship ladder and cable at each moment; constructing a fault assessment model; constructing a physical virtual model and a knowledge model, and constructing a virtual-real twin model. This application can improve the fault perception ability of the ship ladder and cable, more accurately monitor the faults of the ship ladder and cable, improve the authenticity and reliability of the virtual-real twin model, solve the problem of unable to detect potential faults of the cable under forced random disturbances, and ensure the safe operation of the ship ladder.

Description

Technical Field

[0001] This application relates to the field of virtual - reality twin technology, and specifically to a method for constructing a coupled virtual - reality twin model of a ship ladder and its trailing cable under the interference of ocean waves. Background Art

[0002] A marine elevator, abbreviated as a ship ladder, is a special electromechanical equipment fixedly installed on a ship to provide vertical or inclined transportation services for passengers, crew, or cargo. A ship ladder for ocean voyages needs to have the ability to reliably cope with complex sea conditions such as typhoons, ocean waves, and local abnormal weather. The trailing cable of the ship ladder (abbreviation: trailing cable), as an important infrastructure to ensure power supply and information transmission between the elevator car and the control cabinet, the interference of ocean waves or water waves will cause complex coupled motions such as heaving and pitching between the ship ladder and the trailing cable, resulting in interference problems such as collisions, impacts, or frictions between the trailing cable and the shaft facilities or the car of the ship ladder, and ultimately leading to the failure or ineffectiveness of the trailing cable, which has a significant impact on the operational safety and stability of the ship ladder.

[0003] Secondly, the dynamic swaying of the ship ladder's trailing cable is prone to faults such as derailing and jamming. During an ocean voyage in long - term complex sea conditions, if the trailing cable of the ship ladder fails, it will increase the difficulty of ship rescue. However, due to the interference of random ocean waves, the prior art cannot accurately perceive the fault characteristics of the ship ladder's trailing cable, resulting in low authenticity and reliability of the constructed virtual - reality twin model of the trailing cable, and unable to timely detect potential faults or safety risks of the trailing cable. Summary of the Invention

[0004] In order to solve the above - mentioned technical problems, a method for constructing a coupled virtual - reality twin model of a ship ladder and its trailing cable under the interference of ocean waves is provided to solve the existing problems.

[0005] The solution of this application to solve the technical problem is to provide a method for constructing a coupled virtual - reality twin model of a ship ladder and its trailing cable under the interference of ocean waves, including the following steps:

[0006] Construct a three - dimensional wave surface model of short - crested irregular waves, establish the six - degree - of - freedom motion equation of the ship, and generate the motion data of the ship at different degrees of freedom at each moment within a continuous time through numerical simulation; and based on the motion data, establish a simulation scenario of the ship's motion, collect the attitude images of the trailing cable of the ship ladder at each moment, divide the trailing cable of the ship ladder into multiple cable segments, and obtain the stress data of each cable segment in the trailing cable of the ship ladder at each moment.

[0007] Analyze the bending conditions of different positions in each cable segment in the attitude image to determine the bending degree of each cable segment at each moment; predict the stress data of each cable segment at each moment and its local multiple moments, analyze the difference changes between the stress data of each cable segment at each moment and the predicted stress data, and calculate the potential bending weight value of each cable segment at each moment.

[0008] Based on the curvature and the potential bending weight, the coupling eigenvalue of each cable segment at each moment is obtained;

[0009] Analyze the displacement change of each cable segment in the attitude image and the position of each cable segment in the cable following the ship ladder. Combining the coupling eigenvalue, the fault risk value of the cable following the ship ladder at each moment is obtained;

[0010] Based on the motion data at all moments under different degrees of freedom, combining the fault risk value, a fault assessment model is constructed; respectively, based on the physical structure relationship and the text data of the inherent attributes of each entity component on the ship, a physical virtual model and a knowledge model are constructed, and combined with the fault assessment model, a virtual-real twin model is constructed.

[0011] Preferably, the construction of the three-dimensional wave surface model of short-crested irregular waves and the establishment of the six-degree-of-freedom motion equation of the ship include:

[0012] By superimposing multiple wave components with different frequencies and directions, combining the frequency spectrum function and the diffusion function of ocean waves, a three-dimensional wave surface model of short-crested irregular waves is established. Based on the three-dimensional wave surface model, the interference forces and moments of the irregular waves on the ship are calculated, and a six-degree-of-freedom motion equation is established.

[0013] Preferably, the determination of the curvature of each cable segment at each moment includes:

[0014] Construct a three-dimensional geometric model of each cable segment in the attitude image through 3D modeling;

[0015] Use the triangulation algorithm to perform mesh triangulation on the three-dimensional geometric model to generate triangular meshes, and calculate the mean value of the curvatures of all vertices in each triangular mesh, denoted as the mean curvature;

[0016] The curvature is the mean value of the absolute values of the mean curvatures of all triangular meshes in the three-dimensional geometric model corresponding to each cable segment.

[0017] Preferably, the prediction of the stress data of each cable segment at each moment and its local multiple moments includes:

[0018] Each moment and multiple moments before it are denoted as the local time period; based on the stress data of each cable segment at all moments within the local time period, through the prediction model, the predicted stress data of the next moment corresponding to each cable segment at each moment is obtained.

[0019] Preferably, the th cable segment at moment, the potential bending weight The calculation formula is: where is the The predicted stress data of a cable segment at the moment, is the stress data of the th cable segment at the moment, and

[0020] Preferably, the coupling eigenvalue is the product of the curvature and the potential curvature weight.

[0021] Preferably, the displacement change is measured by calculating the attitude displacement amount, and the calculation process is as follows:

[0022] Obtain the image of the ladder with cable at rest, denoted as the static image, and denote the centroid of the three-dimensional geometric model corresponding to each cable segment in the static image as the static centroid;

[0023] Calculate the distance between the centroid of the three-dimensional geometric model corresponding to each cable segment in the attitude image at each moment and the static centroid as the attitude displacement amount of each cable segment at each moment.

[0024] Preferably, obtaining the fault risk value of the ladder with cable at each moment includes:

[0025] Number all cable segments on the ladder with cable in order of position, and use the result of the negative mapping of the serial number of each cable segment as the position weight of each cable segment;

[0026] The fault risk value is the sum of the products of the attitude displacement amounts, the coupling eigenvalues, and the position weights of all cable segments on the ladder with cable.

[0027] Preferably, the construction process of the fault assessment model is as follows:

[0028] Form the motion response sequence of each degree of freedom by the motion data of each degree of freedom of the ship at all moments;

[0029] Form the fault assessment sequence by the fault risk values of the ladder with cable at all moments;

[0030] Use the motion response sequences of all degrees of freedom as the training set, use the fault assessment sequence as the training label, train the neural network model, and denote the trained neural network model as the fault assessment model.

[0031] Preferably, the construction process of the virtual-real twin model:

[0032] Based on the text data of the inherent attributes of each entity component on the ship, construct a knowledge graph as a knowledge model; based on the physical structure relationship of each entity component on the ship, perform 3D modeling to construct a physical virtual model;

[0033] Perform model fusion on the fault assessment model, knowledge model, and physical virtual model to obtain a virtual-real twin model.

[0034] This application has at least the following beneficial effects:

[0035] This application constructs a three-dimensional wave surface model of short-crested irregular waves through the wave energy spectrum along the coast of China and the diffusion function of ITTC. The randomness of the waves is stronger, which is more in line with the real sea wave conditions, making the results of numerical simulation more realistic. By determining the deformation and bending conditions of each cable segment in the attitude image of the cable following the ship ladder on the ship, the bending degree of each cable segment at each moment is determined. The beneficial effect is that it considers the bending degree of the attitude of the cable segment to evaluate the deformation characteristics of the cable segment. Furthermore, predict the stress data of each cable segment within a local time period, and calculate the potential bending weight value based on the difference between the predicted stress data and the measured stress data. The beneficial effect is that it considers the deformation and bending conditions generated by the stress acting on each cable segment. Determine the coupling eigenvalue of each cable segment at each moment. The beneficial effect is that it evaluates the potential deformation and bending characteristics of different cable segments under the influence of potential stress coupling, and then reflects the possibility of deformation of the corresponding cable segment, so as to illustrate the risk of faults such as the cable following the ship ladder getting out of the groove or being stuck, so that the early faults of the cable following the ship ladder can be more accurately perceived in the future. Secondly, obtain the fault risk value of the cable following the ship ladder at each moment through the displacement of each cable segment in the attitude images at different times and the position of each cable segment in the entire cable following the ship ladder. The beneficial effect is that it considers the displacement of each cable segment in the attitude images at different times relative to the static state to evaluate the swing amplitude of each cable segment in the attitude images at each moment. Then, combined with the distance of each cable segment from the top of the shaft and the coupling eigenvalue, the bending degree and swing amplitude of the cable following the ship ladder are evaluated to reflect the degree of fault risk of the cable following the ship ladder and improve the recognition accuracy of the out-of-groove fault of the cable following the ship ladder. Construct a fault assessment model; respectively construct a physical virtual model and a knowledge model based on the text data of the physical structure relationship and inherent attributes of each entity component on the ship, and combine the fault assessment model to construct a virtual-real twin model. The beneficial effect is that it can improve the fault perception ability of the cable following the ship ladder, more accurately monitor the faults of the cable following the ship ladder, improve the authenticity and reliability of the virtual-real twin model, solve the problem of unable to detect potential faults of the cable under forced random disturbances, and ensure the safe operation of the ship ladder. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The following further elaborates in detail on the method for constructing a coupled virtual-real twin model of a ship ladder cable under the interference of sea waves in this application with reference to the accompanying drawings.

[0037] Figure 1It is a flowchart of the steps of the method for constructing a coupled virtual-real twin model of a ship ladder with a cable under the action of sea wave interference provided by an embodiment of the present application;

[0038] Figure 2 It is a schematic structural diagram of a ship ladder with a cable in the ship ladder provided by an embodiment of the present application;

[0039] Figure 3 It is a flowchart of the steps of the method for obtaining the failure risk value of the ship ladder with a cable at each moment provided by an embodiment of the present application. Detailed implementation manners

[0040] In order to make the purpose, technical solutions and advantages of the present application clearer, the method for constructing a coupled virtual-real twin model of a ship ladder with a cable under the action of sea wave interference proposed in the present application will be further described in detail below with reference to the accompanying drawings and implementation examples. It should be understood that the specific implementation examples described herein are only used to explain the present application and are not used to limit the present application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs.

[0042] Please refer to Figure 1 , which shows a flowchart of the steps of the method for constructing a coupled virtual-real twin model of a ship ladder with a cable under the action of sea wave interference provided by an embodiment of the present application. The method includes the following steps:

[0043] Step 1, construct a three-dimensional wave surface model of short-crested irregular waves, establish the six-degree-of-freedom motion equation of the ship, and generate the motion data of the ship at each moment in different degrees of freedom within continuous time through numerical simulation; and based on the motion data, establish a simulation scenario of the ship motion, collect the attitude images of the ship ladder with a cable on the ship at each moment, divide the ship ladder with a cable into multiple cable segments, and obtain the stress data of each cable segment in the ship ladder with a cable at each moment.

[0044] Since the sea wind on the sea surface is random and variable, sea waves usually present as irregular waves, and their forms are mostly short-crested irregular waves or three-dimensional directional waves, and the propagation of waves is multi-directional. Short-crested irregular waves can be regarded as the superposition of infinitely many regular waves with different frequencies, directions, amplitude variations and chaotic phases. In order to describe the sea surface waves, through the motion response of the ship in irregular waves and three-dimensional waves, the interference state of sea waves on the ship is analyzed. Specifically:

[0045] Regard the distribution of wave height as a stationary and ergodic multivariate random process, and use the wave spectrum function to describe it, which is composed of the frequency spectrum function and the spreading function Specifically:

[0046]

[0047] Among them, is the angular frequency of the wave, is the spreading direction of the wave, is the frequency spectrum function, is the spreading function.

[0048] Among them, the main role of the frequency spectrum function is to describe the energy distribution of different frequencies under the current sea state. There are mainly Neumann wave energy spectrum, P-M (Pierson-Moskowitz) spectrum, JONSWAP spectrum, Phillips spectrum and the wave energy spectrum along the coast of China. In this embodiment, the wave energy spectrum along the coast of China proposed by the State Oceanic Administration based on the statistical analysis of the coast of China is adopted as the frequency spectrum function , and the specific expression is:

[0049]

[0050] Among them, is the acceleration of gravity, , is the wind speed, exp() is the exponential function with the natural constant as the base. If the significant wave height is H, it can be approximately converted through Approximate conversion.

[0051] Secondly, the spreading function is used to represent the distribution of wave energy in different directions. Among them, the average wave direction angle is used as the main wave direction angle, denoted as , Each wave propagation direction angle and the main wave direction angle The difference is denoted as , and the calculation method is: , the spreading function can be expressed as:

[0052]

[0053] Among them, s is the spreading factor of the wave, which is an integer. In this embodiment, the spreading factor recommended by the International Towing Tank Conference (ITTC) is adopted.

[0054] Since the randomness of the short-crested wave surface shape is higher and has a greater impact on ship motion, the regular wave is approximated as a small-amplitude simple harmonic wave. Therefore, in this embodiment, through the above frequency spectrum function and the spreading function The constructed wave spectrum function , combined with the Longues-Higgins model, a three-dimensional wave surface model of short-crested irregular waves is established , expressed as:

[0055]

[0056] Wherein, is the amplitude of each component simple harmonic wave, and , is the angular frequency of the component wave of the i-th frequency; is the wave number of the component wave of the i-th frequency; is the direction angle of the component wave in the j-th direction; is the random phase angle, which is uniformly distributed and mutually randomly independent in the interval.

[0057] The ship is approximated as a box-shaped ship, and ship parameters are obtained, specifically including the overall length of the ship, the block coefficient, the ship width, the draft and the molded depth. Based on the Froude-Krylov hypothesis, assuming that the ship's position and heading remain unchanged, based on the three-dimensional wave surface model, the pressure distribution of the wave on the ship's surface is calculated, and the ship's surface is integrated to obtain the wave exciting force and moment, and the six-degree-of-freedom motion equation of the ship is established. Through numerical simulation, the motion data of the ship's transverse movement, longitudinal movement, heave, roll, pitch and heading at different moments in continuous time are generated. Among them, the six degrees of freedom include the transverse movement degree of freedom, the longitudinal movement degree of freedom, the heave degree of freedom, the roll degree of freedom, the pitch degree of freedom and the heading degree of freedom.

[0058] In this embodiment, the random generation frequency of the motion data of each degree of freedom is 0.01 s. As other implementation manners, the implementer can set it by himself according to the actual situation.

[0059] It should be noted that the wave spectrum function , the Longues-Higgins model, the Froude-Krylov hypothesis, the calculation process of the wave exciting force and moment, and the six-degree-of-freedom motion equation are all well-known technologies and will not be elaborated here.

[0060] The ladder cable is one of the important components of the ladder. One end of the ladder cable is connected to the car, and the other end is connected to the top of the hoistway and accesses the control cabinet. Through the ladder cable, the signal transmission communication and electrical connection between the car and the elevator system can be realized. The structural schematic diagram of the ladder cable in the ladder provided in this embodiment is as shown in Figure 2 shown, Figure 2 In 101 is the ladder control cabinet, 102 is the ladder cable, 103 is the car, 104 is the top of the hoistway, 105 is the traction rope, 106 is the bending point of the ladder cable on the top of the hoistway, and 106 is the connection point between the bottom of the car and the ladder cable.

[0061] Therefore, based on the motion data of six degrees of freedom at different times, through the established simulation scenario to simulate the motion of the ship, in this embodiment, a lifting and swaying platform is built to simulate the ship, and a ship ladder trailing cable is arranged on the lifting and swaying platform, so as to construct a simulation scenario to simulate the motion of the ship under the interference of sea waves. Therefore, the ship ladder trailing cable on the lifting and swaying platform will also be affected by the simulated sea waves and generate motion.

[0062] Divide the ship ladder trailing cable into multiple cable segments and number all the cable segments;

[0063] In this embodiment, since the ship is a lifting and swaying platform, therefore, the ship ladder trailing cable on the lifting and swaying platform is divided into 20 cable segments. As other implementation manners, the implementer can set it according to the actual situation; for Figure 2 example, the trailing cable between the bending point 106 of the ship ladder trailing cable at the top of the hoistway and the connection point 107 between the car bottom and the ship ladder trailing cable is divided into 20 cable segments. Among them, all the cable segments are numbered in the order of position. The smaller the serial number of the cable segment closer to the bending point 106 of the ship ladder trailing cable at the top of the hoistway, and the larger the serial number of the cable segment closer to the connection point 107 between the car bottom and the ship ladder trailing cable.

[0064] Install fiber optic stress sensors at the central positions of each cable segment to collect the stress data of each cable segment at different times;

[0065] In this embodiment, the acquisition time interval of the fiber optic stress sensor is 0.01 s, which is consistent with the random generation frequency of the motion data of the degrees of freedom. As other implementation manners, the implementer can set it according to the actual situation.

[0066] Secondly, during the simulation process of the ship ladder trailing cable, use a camera to photograph the motion postures of the ship ladder trailing cable on the lifting and swaying platform to obtain the posture images at each moment;

[0067] In this embodiment, the acquisition frequency of the camera is 0.01 s. As other implementation manners, the implementer can set it according to the actual situation.

[0068] So far, the stress data of each cable segment at each moment and the posture images at each moment are obtained.

[0069] Step 2: Analyze the bending conditions of different positions in each cable segment in the posture image to determine the bending degree of each cable segment at each moment; predict the stress data of each cable segment at each moment and its local multiple moments, analyze the difference changes between the stress data of each cable segment at each moment and the predicted stress data, and calculate the potential bending weight value of each cable segment at each moment; based on the bending degree and the potential bending weight value, obtain the coupling eigenvalue of each cable segment at each moment.

[0070] Under the action of wave interference, the ship will produce multi-dimensional dynamic responses such as rolling and heaving, and transmit the acting forces to the ship ladder and its trailing cable, causing each cable section to bear stresses in different directions and magnitudes, thereby resulting in corresponding deformation bending and forced swinging of the ship ladder trailing cable. The greater the forced deviation of the ship ladder trailing cable, the more likely it is to collide with other non-moving components in the ship ladder shaft, and then faults such as derailing and jamming may occur, easily leading to damage to the ship ladder trailing cable and even safety accidents; secondly, the greater the amplitude of the attitude swing and the higher the bending degree of the cable section, the easier it is to interfere with the shaft facilities such as the shaft wall, guide rail, and car, and then faults such as derailing and jamming may occur.

[0071] Based on the above analysis, by analyzing the bending conditions of each cable section in the attitude image and calculating the degree of bending, specifically:

[0072] Use 3D modeling software to construct a three-dimensional geometric model of each cable section in the attitude image;

[0073] In this embodiment, Blender modeling software is used to construct the three-dimensional geometric model. Among them, Blender modeling software is a well-known technology and will not be elaborated here. As other implementation manners, implementers can adopt other methods of existing technologies, for example, 3ds Max, etc. This embodiment does not make special restrictions on this.

[0074] Use the triangulation algorithm to perform mesh triangulation on the three-dimensional geometric model, generate triangular meshes, and calculate the average value of the curvatures of all vertices in each triangular mesh, denoted as the average curvature;

[0075] In this embodiment, the Delaunay algorithm is used to generate triangular meshes. Among them, both the Delaunay algorithm and the calculation of curvature are well-known technologies and will not be elaborated here.

[0076] Take the average value of the absolute values of the average curvatures of all triangular meshes in the three-dimensional geometric model corresponding to each cable section in the attitude image as the degree of bending of each cable section at each moment;

[0077] It should be noted that the greater the degree of bending, the greater the degree of attitude bending of the cable section.

[0078] Secondly, when each cable section on the ship ladder trailing cable is subjected to stress, corresponding elastic deformation will occur, resulting in bending. After the stress disappears, each cable section on the ship ladder trailing cable will return to its original shape. The short-term change of stress can reflect the potential deformation bending characteristics of the ship ladder trailing cable. Therefore, by analyzing the change of stress data of each cable section at different moments, calculate the potential bending weight value, specifically:

[0079] Denote each moment and multiple moments before it as a local time period;

[0080] In this embodiment, each moment and more than 50 moments thereof are recorded as local time periods. As other implementation manners, the implementer can set them according to the actual situation.

[0081] Based on the stress data of each cable segment at all moments within the local time period, through a prediction model, the predicted stress data of each cable segment at the subsequent moment corresponding to each moment is obtained;

[0082] In this embodiment, an Autoregressive Integrated Moving Average Model (ARIMA) is used for prediction. Among them, the ARIMA model is a well-known technology and will not be elaborated here. As other implementation manners, the implementer can adopt other methods of existing technologies, such as a BP neural network model, etc. This embodiment does not make special restrictions on this.

[0083] The calculation formula of the potential bending weight is as follows:

[0084]

[0085] Among them, is the potential bending weight of the th cable segment at the moment, is the predicted stress data of the th cable segment at the moment, is the stress data of the th cable segment at the moment, is an exponential function with the natural constant as the base, is a preset value greater than 0 to avoid the denominator being 0, and its value range is , in this embodiment, has a value range of 1. As other implementation manners, the implementer can set it according to the actual situation.

[0086] It should be noted that when the stress value of the th cable segment increases and the potential bending weight is greater than 1, corresponding elastic deformation bending is likely to occur, which has a potential promoting effect on the bending of the cable segment; when the stress of the th cable segment decreases, it means that the force that promotes the bending of the ship ladder along with the cable becomes smaller, the potential bending weight is less than 1, the elastic deformation generated by the ship ladder along with the cable will decrease accordingly, and the bending degree will gradually decrease, which has a potential inhibitory effect on the bending of the cable segment.

[0087] Furthermore, based on the degree of bending and the potential bending weight, a coupling eigenvalue is determined, specifically:

[0088] Take the product of the bending degree and the potential bending weight as the coupling eigenvalue of each cable segment at each moment;

[0089] It should be noted that the coupling eigenvalue reflects the comprehensive quantification of the bending degrees of different cable segments in the cable following the ship ladder under the influence of potential stress coupling, evaluates the potential deformation and bending characteristics of the cable segments, and improves the accuracy of the early fault assessment of the cable following the ship ladder; the larger the coupling eigenvalue, the greater the possibility of deformation of the corresponding cable segment at this time, and the higher the risk of faults such as the cable following the ship ladder getting out of the groove or being stuck.

[0090] Thus, the coupling eigenvalue of each cable segment at each moment is obtained.

[0091] Step 3: Analyze the displacement change of each cable segment in the attitude image and the position of each cable segment in the cable following the ship ladder, and combine the coupling eigenvalue to obtain the fault risk value of the cable following the ship ladder at each moment.

[0092] Furthermore, the step flow chart of the method for obtaining the fault risk value of the cable following the ship ladder at each moment provided by the embodiment of the present application is as Figure 3 shown.

[0093] First, analyze the change of the attitude displacement of each cable segment in the attitude image, and calculate the attitude displacement amount, specifically:

[0094] Obtain the image of the cable following the ship ladder when it is stationary, denoted as the stationary image, and denote the centroid of the three-dimensional geometric model corresponding to each cable segment in the stationary image as the stationary centroid;

[0095] Take the distance between the centroid of the three-dimensional geometric model corresponding to each cable segment in the attitude image at each moment and the stationary centroid as the attitude displacement amount of each cable segment at each moment;

[0096] In this embodiment, the distance is measured by calculating the Euclidean distance between the centroid of the three-dimensional geometric model corresponding to each cable segment in the attitude image at each moment and the stationary centroid.

[0097] It should be noted that the larger the attitude displacement amount, the greater the deviation degree of the cable segment under the action of the sea wave and the greater the forced swing amplitude compared with the cable segment in the stationary state.

[0098] Secondly, cable derailment is the most common fault of the cable following the ship ladder. When the cable following the ship ladder is affected by the ship's swaying, not all cable segments' swings will cause derailment. The cable trough is in a "gate" shape. The cable segment near the bending point of the cable following the ship ladder at the top of the shaft has a large swing amplitude, that is, the smaller the serial number of the cable segment, the easier it is to get caught on the cable trough and thus break away from the cable trough. Secondly, considering that the cable segments with higher bending degrees under the influence of potential stress coupling are more likely to interfere with shaft facilities such as the shaft wall, guide rail, and car, resulting in faults such as derailment and jamming. Therefore, by analyzing the serial number situations of different cable segments, combining the attitude displacement and the coupling eigenvalue, calculate the fault risk value, specifically:

[0099] Take the result of the negative mapping of the serial number of each cable segment as the position weight of each cable segment;

[0100] In this embodiment, the process of the negative mapping is as follows: Assume that the serial number of the th cable segment is , and perform negative mapping through the exponential function. Take the result of as the position weight of the th cable segment.

[0101] It should be noted that the larger the position weight, when the cable segment near the bending point of the cable following the ship ladder at the top of the shaft has a higher attitude swing degree, the greater the possibility of failure of the corresponding cable segment.

[0102] Take the sum of the products of the attitude displacement, the coupling eigenvalue, and the position weight of all cable segments on the cable following the ship ladder as the fault risk value of the cable following the ship ladder at each moment;

[0103] It should be noted that the larger the fault risk value, it indicates that the bending degree and swing amplitude of the cable following the ship ladder are larger at this time. The cable following the ship ladder is likely to rub, hook, derail, jam, wind around, etc. with the hoisting rope or the protrusions on the shaft wall, and the fault risk of the cable following the ship ladder is more significant.

[0104] So far, the fault risk value of the cable following the ship ladder at each moment is obtained.

[0105] Step 4, based on the motion data at all moments under different degrees of freedom, combine the fault risk value to construct a fault assessment model; respectively construct a physical virtual model and a knowledge model based on the text data of the physical structure relationship and inherent attributes of each entity component on the ship, and combine the fault assessment model to construct a virtual-real twin model.

[0106] Furthermore, based on the fault risk value and the motion data of 6 degrees of freedom that cause the ship's motion at different moments, construct a fault assessment model, specifically:

[0107] The motion data of each degree of freedom of the ship at all times are combined to form a motion response sequence for each degree of freedom;

[0108] The failure risk values of the ship ladder with cable at all times are combined to form a failure assessment sequence;

[0109] It should be noted that the sequence lengths of the motion response sequence and the failure assessment sequence are the same.

[0110] The motion response sequences of all degrees of freedom are used as the training set, and the failure assessment sequence is used as the training label to train the neural network model. The trained neural network model is denoted as the failure assessment model;

[0111] In this embodiment, a bidirectional attention long short-term memory neural network is used for training. Among them, Adam is used as the optimizer of the neural network model, and the mean square error (MSE) is used as the loss function of the neural network model. The bidirectional attention long short-term memory neural network model is a well-known technology and will not be elaborated here. As other implementation manners, implementers can adopt other methods of existing technologies, such as convolutional neural network models, recurrent neural network models, etc. This embodiment does not make special restrictions on this.

[0112] Based on the text data of the inherent attributes of each entity component on the ship, a knowledge graph is constructed as a knowledge model;

[0113] Based on the physical structure relationship of each entity component on the ship, 3D modeling is carried out to construct a physical virtual model;

[0114] It should be noted that the text data of the inherent attributes of each entity component refers to the abstraction of the attribute knowledge of different entities on the ship. For example, a knowledge model is constructed through the material characteristics of the ship's deck, the size of the hull, the power of the engine, and other inherent attribute features; the physical structure relationship refers to the connection relationship between different entity components. A three-dimensional geometric model is constructed through the ship's design drawings and relevant technical parameters to obtain a physical virtual model.

[0115] In this embodiment, since the ship is simulated by a lifting and swaying platform, therefore, based on the text data of the inherent attributes of each entity component on the lifting and swaying platform, a knowledge model is constructed, and based on the physical structure relationship of each entity component on the lifting and swaying platform, a physical virtual model is constructed.

[0116] It should be noted that the construction methods of the knowledge model and the physical virtual model are well-known technologies and will not be elaborated here.

[0117] The failure assessment model, the knowledge model, and the physical virtual model are fused to construct a virtual-real twin model;

[0118] It should be noted that the virtual-real twin model inputs the generated six-degree-of-freedom motion data into the physical virtual model. According to the six-degree-of-freedom motion data at different moments, the knowledge model is used to control the motion of the physical virtual model. According to the bending and swinging conditions of the ship ladder with the cable in the attitude images at each moment, combined with the fault assessment model, the virtual-real twin model is used to monitor the attitude change of the ship ladder with the cable and the probability of fault occurrence.

[0119] It should be understood that although Figure 1 the steps in the flowchart of Figure 1 are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated in this document, there is no strict order limit for the execution of these steps, and these steps can be executed in other orders. Moreover,

[0120] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0121] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application all belong to the protection scope of the technical solution of the present application.

Claims

1. A method for constructing a virtual-real twin model of a ship ladder and cable coupling under the action of sea wave interference, characterized in that The method includes the following steps: Construct a three-dimensional wave surface model of short-crested irregular waves, establish the six-degree-of-freedom motion equations of the ship, and generate the motion data of the ship at each moment in different degrees of freedom within continuous time through numerical simulation; and based on the motion data, establish a simulation scenario of the ship's motion, collect the attitude images of the ladder cable on the ship at each moment, divide the ladder cable into multiple cable segments, and obtain the stress data of each cable segment in the ladder cable at each moment; Analyze the bending conditions of different positions in each cable segment in the attitude image to determine the bending degree of each cable segment at each moment; predict the stress data of each cable segment at each moment and multiple local moments, analyze the difference changes between the stress data of each cable segment at each moment and the predicted stress data, and calculate the potential bending weight value of each cable segment at each moment; Based on the bending degree and the potential bending weight value, obtain the coupling eigenvalue of each cable segment at each moment; Analyze the displacement change conditions of each cable segment in the attitude image and the positions of each cable segment in the ladder cable, and combine the coupling eigenvalues to obtain the fault risk value of the ladder cable at each moment; Based on the motion data at all moments in different degrees of freedom, combine the fault risk value to construct a fault assessment model; respectively, based on the text data of the physical structure relationship and inherent attributes of each entity component on the ship, construct a physical virtual model and a knowledge model, and combine the fault assessment model to construct a virtual-real twin model.

2. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the influence of sea wave interference according to claim 1, characterized in that, The construction of the three-dimensional wave surface model of short-crested irregular waves and the establishment of the six-degree-of-freedom motion equations of the ship include: Establish a three-dimensional wave surface model of short-crested irregular waves by superimposing multiple wave components with different frequencies and directions, combining the frequency spectrum function and diffusion function of ocean waves, and based on the three-dimensional wave surface model, calculate the interference forces and moments of the irregular waves on the ship to establish the six-degree-of-freedom motion equations.

3. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the action of sea wave interference as described in claim 1, characterized in that, The determination of the bending degree of each cable segment at each moment includes: Construct a three-dimensional geometric model of each cable segment in the attitude image through 3D modeling; Use the triangulation algorithm to perform mesh triangulation on the three-dimensional geometric model to generate triangular meshes, and calculate the mean value of the curvatures of all vertices in each triangular mesh, denoted as the mean curvature; The bending degree is the mean value of the absolute values of the mean curvatures of all triangular meshes in the three-dimensional geometric model corresponding to each cable segment.

4. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the influence of sea wave interference according to claim 1, wherein, The prediction of the stress data of each cable segment at each moment and multiple local moments includes: Denote each moment and multiple moments before it as a local time period; based on the stress data of each cable segment at all moments within the local time period, through the prediction model, obtain the predicted stress data of the next moment corresponding to each cable segment at each moment.

5. The method for constructing a cable-coupled virtual and physical twin model of a ship ladder under the influence of sea wave interference according to claim 4, characterized in that The potential bending weight of the th cable segment at is calculated by the formula: , where is the predicted stress data of the th cable segment at , is the stress data of the th cable segment at , and is the exponential function with the natural constant as the base.

6. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the influence of sea wave interference according to claim 1, characterized in that The coupling eigenvalue is the product of the bending degree and the potential bending weight value.

7. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the influence of sea wave interference according to claim 3, wherein The displacement change condition is measured by calculating the attitude displacement amount, and its calculation process is: Obtain the image of the ladder cable at rest, denoted as the static image, and denote the centroid of the three-dimensional geometric model corresponding to each cable segment in the static image as the static centroid; Calculate the distance between the centroid of the three-dimensional geometric model corresponding to each cable segment in the attitude image at each moment and the static centroid, and use it as the attitude displacement of each cable segment at each moment.

8. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the action of sea wave interference according to claim 7, characterized in that The obtaining of the fault risk value of the ship ladder with cables at each moment includes: Number all cable segments on the ship ladder with cables in order of position, and use the result of the negative mapping of the serial number of each cable segment as the position weight of each cable segment; The fault risk value is the sum of the products of the attitude displacement, the coupling eigenvalue, and the position weight of all cable segments on the ship ladder with cables.

9. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the action of sea wave interference according to claim 1, wherein The construction process of the fault assessment model is as follows: The motion data of each degree of freedom of the ship at all moments are combined to form a motion response sequence for each degree of freedom; The fault risk values of the ship ladder with cables at all moments are combined to form a fault assessment sequence; Use the motion response sequences of all degrees of freedom as the training set, use the fault assessment sequence as the training label, train the neural network model, and denote the trained neural network model as the fault assessment model.

10. The method for constructing a cable-coupled virtual-real twin model of a ship ladder under the influence of sea wave interference according to claim 1, wherein, The construction process of the virtual-real twin model: Based on the text data of the inherent attributes of each entity component on the ship, construct a knowledge graph as a knowledge model; based on the physical structure relationship of each entity component on the ship, perform 3D modeling to construct a physical virtual model; Perform model fusion on the fault assessment model, the knowledge model, and the physical virtual model to obtain the virtual-real twin model.

Images