Construction method of ship ladder cable-following coupling virtual and solid twinborn model under sea wave interference effect

Abstract

The invention relates to the technical field of virtual-solid twinning, in particular to a ship ladder cable-following coupling virtual-solid twinning model construction method under the action of sea wave interference, and the method comprises the steps: obtaining attitude images of a ship ladder at each moment when the ship ladder moves along with a cable, and obtaining stress data of each cable section on the ship ladder along with the cable at each moment; determining the bending degree of each cable section at each moment; calculating the potential bending weight of each cable section at each moment; obtaining a coupling characteristic value of each cable section at each moment; obtaining a fault risk value of the ship ladder along with the cable at each moment; constructing a fault evaluation model; and constructing a physical virtual model and a knowledge model, and constructing a virtual-solid twinborn model. The fault sensing capability of the ship ladder following cable can be improved, the fault of the ship ladder following cable can be monitored more accurately, the authenticity and reliability of a virtual and real twin model are improved, the problem that the potential fault of the following cable cannot be found under forced random disturbance is solved, and the operation safety of the ship ladder is ensured.

Description

Technical Field

[0001] This application relates to the field of virtual - real twin technology, and specifically to a method for constructing a coupled virtual - real 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 for ensuring 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 of the ship ladder and the trailing cable, resulting in interference problems such as collision, impact, or friction 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 existing technology cannot accurately perceive the fault characteristics of the ship ladder's trailing cable, resulting in low authenticity and reliability of the constructed virtual - real twin model of the trailing cable and being unable to timely detect potential faults or safety risks of the trailing cable. Summary of the Invention

[0004] To solve the above - mentioned technical problems, a method for constructing a coupled virtual - real 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 - real twin model of a ship ladder and its trailing cable under the interference of ocean waves, including the following steps: 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'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. 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 of each cable segment at each moment. Based on the curvature and the potential bending weight, the coupling eigenvalue of each cable segment at each moment is obtained; 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. Combine the coupling eigenvalue to obtain the fault risk value of the cable following the ship ladder at each moment; 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, 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.

[0006] 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: By superimposing multiple wave components with different frequencies and directions, combining the frequency spectrum function and diffusion function of ocean waves, establish a three-dimensional wave surface model of short-crested irregular waves. Based on the three-dimensional wave surface model, calculate the disturbing forces and moments of the irregular waves on the ship, and establish a six-degree-of-freedom motion equation.

[0007] Preferably, the determination of the curvature 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 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.

[0008] Preferably, the prediction of the stress data of each cable segment at each moment and its local multiple moments includes: Denote each moment and multiple moments before it 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, obtain the predicted stress data of each cable segment at the next moment corresponding to each moment.

[0009] Preferably, the th cable segment at moment, the potential bending weight The calculation formula is: , where is the predicted stress data of the th cable segment at moment, is the stress data of the th cable segment at moment, is the exponential function with the natural constant as the base.

[0010] Preferably, the coupling eigenvalue is the product of the curvature and the potential curvature weight.

[0011] Preferably, the displacement change is measured by calculating the attitude displacement amount, and the calculation process is as follows: Obtain the image of the ship ladder with the 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 as the attitude displacement amount of each cable segment at each moment.

[0012] Preferably, obtaining the fault risk value of the ship ladder with the cable at each moment includes: Number all the cable segments on the ship ladder with the 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; The fault risk value is the sum of the products of the attitude displacement amounts, the coupling eigenvalues, and the position weights of all the cable segments on the ship ladder with the cable.

[0013] Preferably, the construction process of the fault evaluation model is as follows: 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; Form the fault evaluation sequence by the fault risk values of the ship ladder with the cable at all moments; Use the motion response sequences of all degrees of freedom as the training set, use the fault evaluation sequence as the training label, train the neural network model, and denote the trained neural network model as the fault evaluation model.

[0014] Preferably, the construction process of the virtual-real twin model: Construct a knowledge graph as a knowledge model based on the text data of the inherent attributes of each entity component on the ship; perform 3D modeling based on the physical structure relationship of each entity component on the ship to construct a physical virtual model; Perform model fusion on the fault evaluation model, the knowledge model, and the physical virtual model to obtain the virtual-real twin model.

[0015] This application has at least the following beneficial effects: 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 spreading 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 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, the stress data of each cable segment within a local time period is predicted, and the potential bending weight is calculated 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. The coupling eigenvalue of each cable segment at each moment is determined. The beneficial effect is that it evaluates the potential deformation and bending characteristics of different cable segments considering 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 ladder getting out of the groove or being stuck, so that the early faults of the cable following the ladder can be more accurately detected in the future. Secondly, 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 ladder, the fault risk value of the cable following the ladder at each moment is obtained. 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, by combining the situation 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 ladder are evaluated to reflect the degree of fault risk of the cable following the ladder and improve the recognition accuracy of the out-of-groove fault of the cable following the ladder. A fault assessment model is constructed. Based on the text data of the physical structure relationship and 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. The beneficial effect is that it can improve the fault perception ability of the cable following the ladder, more accurately monitor the faults of the cable following the ladder, improve the authenticity and reliability of the virtual-real twin model, solve the problem of undetected potential faults of the cable under forced random disturbances, and ensure the safe operation of the ladder. Brief Description of the Drawings

[0016] The following further elaborates on the method for constructing a coupled virtual-real twin model of the cable following the ladder under the action of sea wave interference in this application with reference to the drawings.

[0017] Figure 1 It is a flowchart of the steps of the method for constructing a coupled virtual-real twin model of the cable following the ladder under the action of sea wave interference provided in an embodiment of this application; Figure 2 It is a schematic structural diagram of the cable following the ladder in the ladder of this application; Figure 3It is a flowchart of the steps for obtaining the failure risk values of the ship ladder cable at each moment provided by the embodiments of the present application. Detailed implementation manners

[0018] In order to make the purpose, technical solutions and advantages of the present application clearer, the following further details the method for constructing a coupled virtual-real twin model of a ship ladder cable under the action of sea wave interference proposed by the present application in combination with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0019] 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.

[0020] 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 cable under the action of sea wave interference provided by an embodiment of the present application. The method includes the following steps: 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 under different degrees of freedom in 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 ship ladder cable on the ship at each moment, divide the ship ladder cable into multiple cable segments, and obtain the stress data of each cable segment in the ship ladder cable at each moment.

[0021] Due to the randomness and variability of the sea wind on the sea surface, 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, the interference state of sea waves on the ship is analyzed through the motion response of the ship in irregular waves and three-dimensional waves, specifically: Regarding the distribution of wave heights as a stationary and ergodic multivariate random process, the wave spectrum function is used to describe it, which is composed of the frequency spectrum function and the spreading function , specifically: 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.

[0022] Among them, the frequency spectrum function The main function is to describe the energy distribution of different frequencies under the current sea conditions. 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 National Oceanic Administration based on the statistical analysis of the coast of China is adopted as the frequency spectrum function , and the specific expression is: Among them, is the acceleration due to 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 .

[0023] 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 , The difference between each wave propagation direction angle and the main wave direction angle is denoted as , and the calculation method is: , and the spreading function can be expressed as: 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.

[0024] 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, the wave spectrum function constructed by the above frequency spectrum function and the spreading function , combined with the Longues-Higgins model, establishes a three-dimensional wave surface model of short-crested irregular waves, expressed as: Among them, 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 a random phase angle, which is uniformly distributed and mutually independent randomly in the

[0025] 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-Kriloff hypothesis, assuming that the position and heading of the ship remain unchanged, based on the three-dimensional wave surface model, the pressure distribution of the wave on the ship surface is calculated, and the ship 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 sway, surge, heave, roll, pitch, and heading at different moments in continuous time are generated, where the six degrees of freedom include the sway degree of freedom, the surge degree of freedom, the heave degree of freedom, the roll degree of freedom, the pitch degree of freedom, and the heading degree of freedom.

[0026] 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 according to the actual situation.

[0027] It should be noted that the wave spectrum function , the Longues-Higgins model, the Froude-Kriloff 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.

[0028] The ladder cable is one of the important components of the ship 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 ship ladder provided in this embodiment is as Figure 2 shown, Figure 2 In it, 101 is the ship 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.

[0029] Therefore, based on the motion data of the six degrees of freedom at different moments, through the established simulation scenario, the motion situation of the ship is simulated. In this embodiment, the ship is simulated by building a lifting and swaying platform, and the ladder cable is arranged on the lifting and swaying platform, so as to construct a simulation scenario to simulate the motion situation of the ship under the interference of sea waves. Therefore, the ladder cable on the lifting and swaying platform will also be affected by the simulated sea waves and generate motion.

[0030] The ladder cable is divided into multiple cable segments, and all cable segments are numbered; In this embodiment, since the ship is a lifting and swaying platform, the cable of the ship ladder 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; taking Figure 2 as an example, that is, the cable between the bending point 106 of the cable of the ship ladder at the top of the hoistway and the connection point 107 between the bottom of the car and the cable of the ship ladder is divided into 20 cable segments. Among them, all the cable segments are numbered in the order of their positions. The smaller the serial number of the cable segment closer to the bending point 106 of the cable of the ship ladder at the top of the hoistway, and the larger the serial number of the cable segment closer to the connection point 107 between the bottom of the car and the cable of the ship ladder.

[0031] Optical fiber stress sensors are installed at the central positions of each cable segment to collect the stress data of each cable segment at different times; In this embodiment, the acquisition time interval of the optical fiber stress sensors 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.

[0032] Secondly, during the simulation process of the cable of the ship ladder, a camera is used to photograph the motion postures of the cable of the ship ladder on the lifting and swaying platform to obtain the posture images at each moment; 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.

[0033] So far, the stress data of each cable segment at each moment and the posture images at each moment are obtained.

[0034] 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 at 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.

[0035] Under the action of sea wave interference, the ship will produce multi-dimensional dynamic responses such as swaying and heaving, and transmit the acting forces to the ship ladder and the cable of the ship ladder, so that each cable segment bears stresses in different directions and magnitudes, which in turn causes the cable of the ship ladder to undergo corresponding deformation bending and forced swinging. The greater the forced deviation of the cable of the ship ladder, the more likely it is to collide with other non-moving components in the ship ladder hoistway, and then faults such as derailing and jamming will occur, which easily leads to the cable of the ship ladder being scratched, and even safety accidents may occur; secondly, the greater the amplitude of the posture swing and the higher the bending degree of the cable segment, it is easy to interfere with the hoistway facilities such as the hoistway wall, guide rail, and car, and then faults such as derailing and jamming will occur.

[0036] Based on the above analysis, by analyzing the bending conditions of each cable segment in the attitude image, the degree of bending is calculated as follows: Use 3D modeling software to construct a three-dimensional geometric model of each cable segment in the attitude image; 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, such as 3ds Max, etc. This embodiment does not make special restrictions on this.

[0037] Use the triangulation algorithm to perform mesh triangulation on the three-dimensional geometric model, generate triangular meshes, and calculate the mean value of the curvatures of all vertices in each triangular mesh, denoted as the average curvature; 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.

[0038] Take the mean value of the absolute values of the average curvatures of all triangular meshes in the three-dimensional geometric model corresponding to each cable segment in the attitude image as the degree of bending of each cable segment at each moment; It should be noted that the greater the degree of bending, the greater the degree of bending of the attitude of the cable segment.

[0039] Secondly, when each cable segment on the ladder following cable is subjected to stress, corresponding elastic deformation will occur and cause bending. When the stress disappears, each cable segment on the ladder following cable will return to its original shape. The short-term change of stress can reflect the potential deformation and bending characteristics of the ladder following cable. Therefore, by analyzing the change of stress data of each cable segment at different moments, the potential bending weight value is calculated as follows: Denote each moment and multiple moments before it as the local time period; In this embodiment, each moment and more than 50 moments before it are denoted as the local time period. As other implementation manners, implementers can set it according to the actual situation.

[0040] 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; In this embodiment, the 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, implementers can adopt other methods of existing technologies, such as the BP neural network model, etc. This embodiment does not make special restrictions on this.

[0041] The calculation formula for the potential bending weight is as follows: Wherein, is the potential bending weight of the th cable segment at moment, is the predicted stress data of the th cable segment at moment, is the stress data of the th cable segment at moment, is the 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.

[0042] 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 promoting 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.

[0043] Furthermore, based on the bending degree and the potential bending weight, a coupling eigenvalue is determined, specifically: The product of the bending degree and the potential bending weight is used as the coupling eigenvalue of each cable segment at each moment; It should be noted that the coupling eigenvalue reflects the comprehensive quantification of the bending degrees of different cable segments in the ship ladder along with the cable considering the influence of potential stress coupling, evaluates the potential deformation bending characteristics of the cable segments, and improves the accuracy of the early fault assessment of the ship ladder along with the cable; 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 ship ladder along with the cable getting out of the groove or being stuck.

[0044] Thus, the coupling eigenvalue of each cable segment at each moment is obtained.

[0045] Step 3: Analyze the displacement change of each cable segment in the attitude image and the position of each cable segment in the ship ladder along with the cable, and combine the coupling eigenvalue to obtain the fault risk value of the ship ladder along with the cable at each moment.

[0046] Further, the flowchart of the method for obtaining the fault risk value of the ship ladder trailing cable at each moment provided by the embodiment of the present application is as follows Figure 3 shown.

[0047] First, analyze the change of the attitude displacement of each cable segment in the attitude image, and calculate the attitude displacement amount. Specifically: Obtain the image of the ship ladder trailing 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; 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 static centroid as the attitude displacement amount of each cable segment at each moment; 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 static centroid.

[0048] It should be noted that the larger the attitude displacement amount, the greater the deviation degree of the cable segment under the action of sea waves and the greater the forced swing amplitude compared with the cable segment in the static state.

[0049] Secondly, derailment is the most common fault of the ship ladder trailing cable. When the ship ladder trailing cable is affected by the shaking of the ship, not all cable segment swings will cause derailment. The cable trough is in the shape of a "door". The cable segment near the bending part of the ship ladder trailing cable 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 hang on the cable trough and thus derail from the cable trough. Secondly, considering that the cable segment with a higher bending degree under the influence of potential stress coupling is more likely to interfere with the shaft facilities such as the shaft wall, guide rail, and car, resulting in faults such as derailment and jamming. Therefore, analyze the serial number situation of different cable segments, and combine the attitude displacement amount and the coupling eigenvalue to calculate the fault risk value. Specifically: Take the result of the negative mapping of the serial number of each cable segment as the position weight of each cable segment; 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, and take the result of as the position weight of the th cable segment.

[0050] It should be noted that the larger the position weight, when the cable segment near the bending part of the ship ladder trailing cable at the top of the shaft has a higher attitude swing degree, the greater the possibility of the corresponding cable segment having a fault.

[0051] The sum of the products of the attitude displacement amounts, the coupling eigenvalue, and the position weights of all cable segments of the ship ladder cable is used as the failure risk value of the ship ladder cable at each moment; It should be noted that the larger the failure risk value, the greater the bending degree and swing amplitude of the ship ladder cable at this time, and the ship ladder cable is prone to problems such as rubbing, hooking, de-slotting, jamming, and entanglement with the traction rope or the protrusions on the hoistway wall, and the failure risk of the ship ladder cable is more significant.

[0052] Thus, the failure risk value of the ship ladder cable at each moment is obtained.

[0053] Step 4, based on the motion data at all moments under different degrees of freedom, combined with the failure risk value, construct a failure 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 combined with the failure assessment model, construct a virtual-real twin model.

[0054] Furthermore, based on the failure risk value and the motion data of the 6 degrees of freedom that cause the ship's motion at different times, construct a failure assessment model, specifically: 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 failure risk values of the ship ladder cable at all moments are combined to form a failure assessment sequence; It should be noted that the sequence lengths of the motion response sequence and the failure assessment sequence are the same.

[0055] Use the motion response sequences of all degrees of freedom as the training set, and the failure assessment sequence as the training label to train the neural network model. The trained neural network model is denoted as the failure assessment model; 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. Among them, the bidirectional attention long short-term memory neural network model is a well-known technology and will not be elaborated here. As other implementation methods, implementers can use 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.

[0056] 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; 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 inherent attribute characteristics such as the material characteristics of the ship's upper deck, the size of the hull, and the power of the engine; the physical structure relationship refers to the connection relationship between different entity components, and a three-dimensional geometric model is constructed through the ship's design drawings and relevant technical parameters to obtain a physical virtual model.

[0057] In this embodiment, since the ship is simulated by the lifting and swaying platform, therefore, a knowledge model is constructed based on the text data of the inherent attributes of each entity component on the lifting and swaying platform, and a physical virtual model is constructed based on the physical structure relationship of each entity component on the lifting and swaying platform.

[0058] 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.

[0059] The fault assessment model, the knowledge model, and the physical virtual model are fused to construct a virtual-real twin model; 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 times, 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 attitude change of the ship ladder with the cable and the probability of fault occurrence are monitored through the virtual-real twin model.

[0060] It should be understood that although Figure 1 the steps in the flowchart 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 article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, Figure 1 at least a part of the steps in

[0061] may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0062] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to 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 modifications, equivalent changes, and decorations made to the above embodiments based on the technical essence of the present application without departing from the technical solution of the present application all fall within 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 coupled with a cable under the action of sea wave interference, characterized in that: The method comprises the following steps: Construct a three-dimensional wave surface model of short-peak 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 in continuous time through numerical simulation; and based on the motion data, establish a simulation scene of the ship's motion, collect the posture images of the ship's ladder cable at each moment, divide the ship's ladder cable into multiple cable segments, and obtain the stress data of each cable segment in the ship's ladder cable at each moment; 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 multiple local moments, analyze the difference between the stress data of each cable segment at each moment and the predicted stress data, and calculate the potential bending weight of each cable segment at each moment; Based on the curvature and the potential curvature weight, obtaining a coupling characteristic value of each cable segment at each time; Analyze the displacement change of each cable segment in the posture image and the position of each cable segment in the ship ladder cable, and combine the coupling characteristic value to obtain the fault risk value of the ship ladder cable at each time; Based on the motion data at all times under different degrees of freedom and combined with the fault risk value, a fault assessment model is constructed; based on the text data of the physical structure relationship and inherent properties 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.

2. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference according to claim 1 is characterized in that: The three-dimensional wave surface model of the short-peak irregular wave is constructed to establish the six-degree-of-freedom motion equation of the ship, including: By superimposing multiple wave components of different frequencies and directions and combining the frequency spectrum function and diffusion function of the waves, a three-dimensional wave surface model of short-peak irregular waves is established. Based on the three-dimensional wave surface model, the interference force and torque of irregular waves on the ship are calculated, and the six-degree-of-freedom motion equation is established.

3. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 1, characterized in that: Determining the curvature of each cable segment at each moment includes: Constructing a three-dimensional geometric model of each cable segment in the posture image by 3D modeling; Using a triangulation algorithm to mesh the three-dimensional geometric model to generate a triangular mesh, and calculating the mean value of the curvature of all vertices in each triangular mesh, which is recorded as the average curvature; The curvature is the average of the absolute values ​​of the average curvatures of all triangular meshes in the three-dimensional geometric model corresponding to each cable segment.

4. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 1, characterized in that: The method of predicting the stress data of each cable segment at each time and at multiple local time points includes: Each moment and the multiple moments before it are recorded as a local period; based on the stress data of each cable segment at all moments in the local period, the predicted stress data of each cable segment at the next moment corresponding to each moment is obtained through the prediction model.

5. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 4, characterized in that: No. The cable segment Potential bending weight at time The calculation formula is: ,in, For the The cable segment The predicted stress data at time For the The cable segment The stress data at the moment, is an exponential function with a natural constant as its base.

6. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 1, characterized in that: The coupling eigenvalue is the product of the curvature and the potential curvature weight.

7. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 3, characterized in that: The displacement change is measured by calculating the posture displacement, and the calculation process is: Acquire an image of the ship ladder when it is stationary along with the cable, record it as a stationary image, and record the centroid of the three-dimensional geometric model corresponding to each cable segment in the stationary image as the stationary centroid; The distance between the center of mass of the three-dimensional geometric model corresponding to each cable segment in the posture image at each moment and the stationary center of mass is calculated as the posture displacement of each cable segment at each moment.

8. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 7, characterized in that: The method of obtaining the failure risk value of the ship ladder along with the cable at each time includes: All cable segments on the ship ladder are numbered in order of position, and the result of negative mapping the serial number of each cable segment is used as the position weight of each cable segment; The fault risk value is the cumulative sum of the products of the attitude displacement, the coupling characteristic value and the position weight of all cable segments on the ship ladder cable.

9. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 1, characterized in that: The construction process of the fault assessment model is as follows: The motion data of each degree of freedom of the ship at all times are combined into a motion response sequence of each degree of freedom; The failure risk values ​​of the ship ladder and cable at all times are combined to form a failure assessment sequence; The motion response sequences of all degrees of freedom are used as training sets, and the fault assessment sequences are used as training labels to train the neural network model, and the trained neural network model is recorded as a fault assessment model.

10. The method for constructing a virtual-real twin model of a ship ladder coupled with a cable under the action of sea wave interference as claimed in claim 1, characterized in that: The construction process of the virtual-real twin model: Based on the text data of the inherent attributes of each physical component on the ship, a knowledge graph is constructed as a knowledge model; 3D modeling is performed based on the physical structural relationship of each physical component on the ship to construct a physical virtual model; The fault assessment model, knowledge model and physical virtual model are integrated to obtain a virtual-reality twin model.

Images