Method for predicting loads and motions of a catamaran transfer vehicle

Abstract

The present application relates to a kind of load and motion prediction method of floating body inter-springboard transfer vehicle, using quasi-static method, according to certain time step, carry out each time geometric modeling analysis, in combination with the static water force integral solution theory of floating body floating state, construct the equation group with each floating body trim angle and springboard angle as unknown, solve equation group by iterative method, obtain the value of each time floating body relevant posture, load, and then can carry out vehicle transfer safety evaluation, support guarantee scheme design and operation capability boundary determination, better accuracy and convenience;By constructing the proxy model of each floating body trim angle and springboard angle and each floating body buoyancy and center of buoyancy coordinate, the calculation time can be effectively shortened under the premise of ensuring calculation accuracy, and the demand for computing power is reduced.The vehicle loading and unloading transfer operation of roll-on / roll-off ship and roll-on / roll-off boat.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of maritime operation technology, in particular to a kind of load and movement prediction method of floating body interval jump board lap joint transfer vehicle. BACKGROUND

[0002] On the sea, when sea condition is good, vehicle transfer is carried out by establishing vehicle channel through jump board lap joint between roll-on / roll-off ship, roll-on / roll-off dinghy and other floating bodies, which is a kind of efficient vehicle transfer mode, avoids dependence on roll-on / roll-off wharf, and improves flexibility of vehicle roll-on / roll-off transportation. With movement of vehicle, floating state of each floating body, angle of jump board, load of related components change, and dangerous state such as collision, overload and vehicle impassability may occur, so it is necessary to predict floating body movement and load during vehicle transfer in advance. At present, only inherent parameters such as longitudinal moment per centimeter of each floating body are used for estimation, and there is lack of accurate prediction method, which is difficult to support guarantee scheme design and operation capacity boundary determination. SUMMARY

[0003] In view of load and movement prediction problem of vehicle transfer through jump board lap joint between roll-on / roll-off ship, roll-on / roll-off dinghy and other floating bodies when sea condition is good on the sea, a kind of load and movement prediction method of floating body interval jump board lap joint transfer vehicle is proposed, which can accurately predict change of floating state of each floating body, angle of jump board and load of related components during vehicle transfer between floating bodies, and further guide safety and feasibility analysis of operation, and has good accuracy and convenience.

[0004] The technical scheme of the present application is as follows: a kind of load and movement prediction method of floating body interval jump board lap joint transfer vehicle, specifically comprising the following steps:

[0005] 1) a geometric and physical model of multiple floating bodies through jump board lap joint is established, according to the geometric and physical model, floating state of each floating body is determined by constructing equation group with unknown variables of each floating body inclination angle and jump board slope, according to integral solution theory of hydrostatic force of floating body;

[0006] 2) vehicle transfer initial time t0 is obtained, vehicle weight and position are input, according to geometric relationship, equation group of floating force, floating center and attitude of each floating body is combined, and values of related attitude, coordinate and load of each floating body at this time are solved according to force and torque balance equation;

[0007] 3) time step △t is taken, vehicle transfer next time initial time t0+△t is taken, position of vehicle is determined according to vehicle speed, equation group of floating force, floating center and attitude of each floating body is combined, and values of related attitude, coordinate and load of each floating body at this time are solved according to force and torque balance equation;

[0008] 4) sequentially calculate the values of the relevant attitudes, coordinates and loads of each floating body at each time t0+n△t, to obtain the time history values of the floating state, the ramp angle and the relevant component load of each floating body;

[0009] 5) based on the data obtained in steps 2) to 4), build a proxy model of the trim angle and the ramp slope of each floating body and the buoyancy and the coordinates of the floating center of each floating body by using an existing adaptive algorithm, to calculate the values of the relevant attitudes, coordinates and loads of each floating body under each vehicle driving state, as the basis for safety and feasibility analysis.

[0010] Further, the step 1) geometric physical model building: a two-dimensional model is built in which both the load and the motion are in the longitudinal section of each floating body, nodes are set on the model, including the center of gravity of each floating body, the floating center of each floating body, the center of gravity of the ramp, the center of gravity of the vehicle, the two end points of the cable, and the two connection points of the ramp, and constraints are established for the nodes in the model.

[0011] Further, the step 1) equation set building: after the geometric physical model is built, the force analysis of the lapping system in the geometric physical model is performed according to the quasi-static method, the geometric relationship of the force is established, and based on the geometric relationship, if any set of the trim angle and the ramp slope of each floating body is known, the draft of the rib where the center of gravity of each floating body is located is obtained, and the buoyancy and the coordinates of the floating center of each floating body are calculated by means of the integral calculation of the static pressure at each position on the surface of each floating body, to obtain the simultaneous equation set of the buoyancy and the coordinates of the floating center of each floating body.

[0012] Further, the step 5) proxy model building step is:

[0013] A: the data obtained in steps 2) to 4) are discrete points of the floating body attitude values, and on this basis, a sufficient number of discrete points of the floating body attitude values are designed by using a sampling design method;

[0014] B: the buoyancy and the coordinates of the floating center of each floating body corresponding to each discrete point designed in step A are calculated by means of the integral calculation of the static water pressure, and the calculation results are prediction values;

[0015] C: the interpolation in the multidimensional space is completed by using the discrete points obtained in step B and the prediction values obtained by calculation, to build a proxy model.

[0016] Further, the sampling design method is one of the Latin hypercube design method, the Sobol design method and the orthogonal test design method.

[0017] Further, the proxy model is a typical single proxy model using the Kriging model, or a combined proxy model formed by combining different proxy models.

[0018] An application of a load and motion prediction method for vehicle transfer via inter-floor gangway connection, applicable to the loading and unloading of transfer vehicles on roll-on / roll-off ships and small roll-on / roll-off boats.

[0019] The application of the load and motion prediction method for the inter-float gangway transfer vehicle is included in the safety assessment of vehicle transfer during the loading and unloading operations of roll-on / roll-off ships and small roll-on / roll-off boats, the design of support and protection schemes, and the determination of operational capacity boundaries.

[0020] The beneficial effects of this invention are as follows: The method for predicting the load and motion of vehicles transferring between floating bodies using ramps employs a quasi-static method. Geometric modeling analysis is performed at each moment according to a certain time step. Combined with the hydrostatic integral solution theory of the floating state of the floating bodies, a system of equations is constructed with the pitch angle of each floating body and the ramp angle as unknowns. The system of equations is solved iteratively to obtain the values ​​of the relevant attitude and load of the floating bodies at each moment. This allows for the assessment of vehicle transfer safety, supports the design of guarantee schemes, and determines the boundaries of operational capabilities, demonstrating good accuracy and convenience. Furthermore, by constructing proxy models of the pitch angle and ramp angle of each floating body with the buoyancy and coordinates of the center of buoyancy of each floating body, the calculation time can be effectively shortened while ensuring calculation accuracy, reducing the demand for computational power. Attached Figure Description

[0021] Figure 1 This is a side view of the initial moment when the large ship and small boat of the present invention are joined by the bow and stern of the platform;

[0022] Figure 2 This is a side view of a typical moment in which a large ship and a small boat transfer vehicles via a platform at the bow and stern.

[0023] Figure 3 For the present invention Figure 2 Force analysis diagram of the small boat at a typical moment;

[0024] Figure 4 For the present invention Figure 2 Force analysis diagram of a large ship's stern ramp at a typical moment. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] A method for predicting the load and movement of vehicles transferring between floating bodies via connecting ramps: To accurately predict changes in vehicle data during the transfer process between floating bodies, the technical solution adopted in this invention is as follows:

[0027] First step: Establish the geometric and physical model of the multiple floating bodies connected by the ramp, and according to the geometric and physical model, combine the hydrostatic force integral solving theory of the floating state of the floating body, and construct the equation group for determining the buoyancy, center of buoyancy and attitude of each floating body with the unknown variables of the trim angle of each floating body and the slope of the ramp;

[0028] Second step: Obtain the initial time t0 of vehicle transfer, input the vehicle weight and the position, and according to the geometric relationship, combine the equation group of the buoyancy, center of buoyancy and attitude of the floating body, and solve the values of the related attitude, coordinate and load of each floating body at this time according to the force and moment balance equation;

[0029] Third step: Take the time step △t, and the initial time t0+△t of the next time of vehicle transfer, determine the position of the vehicle according to the vehicle speed, combine the equation group of the buoyancy, center of buoyancy and attitude of the floating body, and solve the values of the related attitude, coordinate and load of each floating body at this time according to the force and moment balance equation;

[0030] Fourth step: Calculate the values of the related attitude, coordinate and load of each floating body at each time t0+n△t in turn, and obtain the time history values of the floating state, ramp angle and related component load of each floating body of interest;

[0031] Fifth step: Through the existing adaptive algorithm, construct the surrogate model of the trim angle of each floating body and the slope of the ramp and the buoyancy and center of buoyancy coordinate of each floating body based on the data obtained in steps two to four, which is used to calculate the values of the related attitude, coordinate and load of each floating body under each vehicle driving state, and serves as the basis for safety and feasibility analysis.

[0032] The whole calculation process can be automatically carried out by establishing a program, which is reliable and convenient.

[0033] In the prediction process, in order to determine the relationship between the buoyancy, center of buoyancy and attitude of the floating body, considering that the method of calculating the static water pressure integral on the surface of the floating body has a large workload, in order to reduce the calculation amount and improve the calculation efficiency of the program under the condition of ensuring the engineering precision, a surrogate model representing the relationship between the buoyancy, center of buoyancy and attitude of the floating body can be constructed, and the specific steps are as follows:

[0034] (1) Use appropriate sampling design method to design a sufficient number of discrete points of the attitude of the floating body, and the sampling design method can use Latin hypercube design method, Sobol design method, orthogonal test design method, etc.;

[0035] (2) For each discrete point obtained after sampling design, the corresponding buoyancy and center of buoyancy coordinate value of each floating body is calculated through the static water pressure integral calculation, and the calculation result is the prediction value;

[0036] (3) Using the discrete points and forecast values ​​obtained in step (2), interpolation in multidimensional space is completed to establish a surrogate model. When the forecast values ​​corresponding to spatial points outside the discrete points are needed, the new input conditions are simply substituted into the existing surrogate model to obtain the corresponding output (forecast value). The surrogate model can adopt typical single surrogate models such as the Kriging model, or different surrogate models can be combined to form a combined surrogate model.

[0037] Figures 1 to 4 This is a computational geometry model of a specific embodiment of the present invention, which is a typical case of a large roll-on / roll-off ship (hereinafter referred to as: large ship) and a small boat transferring vehicles by means of a bow-stern connection on a floating transition platform (hereinafter referred to as: platform).

[0038] like Figure 1 The diagram shows a side view of the initial moment when the large ship and small boat are joined by the platform bow and stern. At this time, neither the platform nor the small boat carries any vehicles. Platform 20 is placed on the water surface at the stern of the large ship 10. The stern ramp 11 of the large ship is attached to platform 20 and is in a free-floating state. The bow ramp 31 of the small boat is attached to platform 20 and is in a free-floating state. At the same time, the small boat 30 is connected to platform 20 by cable 40 to prevent the small boat 30 from moving backward relative to platform 20. Vehicles 51 and 52 slowly enter platform 20 sequentially from the vehicle compartment of the large ship 10 via the stern ramp 11, and then travel to the small boat 30 via the bow ramp 31, or vice versa. Figure 2 As shown, one vehicle has moved onto the small boat 30, and the other vehicle has moved onto the floating transfer platform 20. Throughout the vehicle movement, key loads and motion parameters such as the buoyancy of the small boat 30, platform 20, and large ship 10, the angles between the small boat's bow ramp 31 and the large ship's stern ramp 11 and the deck surface of platform 20, the tension of the cable 40 connecting the small boat 30 and the platform, and the supporting forces at the ends of the small boat's bow ramp 31 and the large ship's stern ramp 11 continuously change and need to be solved to support the safety assessment of vehicle transfer.

[0039] A. First, basic assumptions are proposed to appropriately simplify the computational model. These basic assumptions include:

[0040] 1) At any given moment, the small boat 30 does not generate any forward or backward power, the vehicle travels at a slow speed, and the entire system satisfies static balance.

[0041] 2) At any given time, the large ship 10 remains stationary;

[0042] 3) At any given time, the large ship 10, platform 20, and small boat 30 do not tilt.

[0043] 4) The constraint of the end of the small boat's bow ramp 31 on the platform 20 can be regarded as a hinge;

[0044] 5) The constraint of the large ship stern ramp 11 end on the platform 20 can be regarded as a hinge;

[0045] 6) The connection cable 40 between the dinghy 30 and the platform 20 can be treated as a spring, i.e. the cable 40 obeys Hooke's law when it is tensioned;

[0046] 7) At the initial moment when the dinghy 30 and the platform 20 are connected (i.e. the moment t0), the cable 40 is of the original length, i.e. no tension. Figure 1

[0047] B. Secondly, the coordinate system and the parameters of the calculation geometry model are defined:

[0048] Since at any moment, the load and the motion are in the longitudinal section of the large ship 10, the platform 20 and the dinghy 30, the model is simplified as a two-dimensional model, and the calculation model shown in FIGS. 1 and 2 is used, and the origin of the coordinate system is defined as point I (the hinge point where the stern ramp 11 of the large ship is connected to the hull of the large ship 10), the x direction is horizontal, and the positive direction is to the left, and the z direction is vertical, and the positive direction is upward. Figure 1 Figure 2

[0049] Figures 1 to 4 In the above, the nodes are explained as follows:

[0050] A point - the point where the bow ramp 31 of the dinghy is connected to the platform 20;

[0051] B point - the hinge point where the bow ramp 31 of the dinghy is connected to the hull of the dinghy 30;

[0052] D point - the point where the cable 40 is out of the dinghy 30;

[0053] E point - the point where the cable 40 is connected to the platform 20;

[0054] H point - the point where the stern ramp 11 of the large ship is connected to the platform 20;

[0055] I point - the hinge point where the stern ramp 11 of the large ship is connected to the hull of the large ship 10;

[0056] J point - the center of gravity of the stern ramp 11 of the large ship;

[0057] M point - the center of gravity of the bow ramp 31 of the dinghy;

[0058] N point - the center of gravity of the first vehicle 51;

[0059] V point - the center of gravity of the first vehicle 52;

[0060] Q point - the center of gravity of the hull of the dinghy 30 (excluding the bow ramp 31);

[0061] R point - the center of gravity of the platform 20;

[0062] ​​​Point P – the center of buoyancy of the small boat at 30 degrees;

[0063] Point S – the center of buoyancy on platform 20.

[0064] The main parameters are defined in Table 1.

[0065] Table 1. Definition of main parameters of the model

[0066]

[0067]

[0068] C. Next, following the quasi-static method, for Figure 2 Stress analysis of the interlocking system:

[0069] For the hull of the small boat 30 (excluding the bow ramp 31), if the net force in the x-direction is 0, then we can obtain...

[0070] F bx =F t ·cosb (1)

[0071] like Figure 3 As shown, for the small boat's bow ramp 31, the resultant torque about point A is 0, and the resultant forces in both the x and z directions are 0. Therefore, we can obtain...

[0072]

[0073] F ax =F t ·cosb (3)

[0074]

[0075] For the hull of the small boat 30 (excluding the bow ramp 31), if the resultant force in the z-direction is 0 and the resultant moment about point B is 0, then we can obtain...

[0076] F p =G q +G n +F bz +F t sinb (5)

[0077]

[0078] For platform 20, given that the net force in the x-direction is 0, we can obtain...

[0079] F hx =F t ·cosb1 (7)

[0080] like Figure 4 As shown, for the stern ramp 11 of a large ship, the resultant moment about point I is 0, which yields the following:

[0081]

[0082] For platform 20, the resultant force in z direction is 0, and the resultant moment about point A is 0, we have

[0083] F s = G r + G v + F az + F hz - F t sinb1 (9)

[0084]

[0085] D, then, we have the following equations:

[0086] According to equations (1) to (10), and the geometric relationship, we have

[0087] F p = G q + G n + F bz + F t sinb1 (11)

[0088]

[0089] F s = G r + G v + F az + F hz - F t sinb1 (13)

[0090]

[0091] According to the geometric relationship, if the value of any set of (φ1, φ2, φ3, φ4) is known, the attitude of large ship stern ramp 11, platform 20 and dinghy 30 is completely determined, the longitudinal inclination angle of dinghy 30 and platform 20 and the water depth of the rib position where the center of gravity is located can be obtained, the size of the buoyancy and the coordinates of the center of buoyancy of the two can be calculated by calculating the static pressure of each position on the surface of the two and then integrating, that is, the Froude-Krylov diagram of the two is drawn, so

[0092] F p = f3(φ1, φ2, φ3, φ4) (15)

[0093] x BP = f4(φ1, φ2, φ3, φ4) (16)

[0094] F s=f5(φ1,φ2,φ3,φ4) (17)

[0095] x AS =f6(φ1,φ2,φ3,φ4) (18)

[0096] Substituting equations (15) to (18) into equations (11) to (14), we obtain a system of four equations with unknowns φ1, φ2, φ3, φ4, and F. t There are 5 in total.

[0097] for Figure 1 The initial time shown can be regarded as Figure 2 In a special case of the time-matter model, the above four equations still apply, and F... t =0, G n =0, G v =0, therefore the system of equations is closed at the initial moment, and theoretically, the values ​​of φ1, φ2, φ3, and φ4 can be solved, thus obtaining the initial length of the cable 40. Figure 2 At any given moment, according to geometric relationships, the length of cable 40 is a function of φ1, φ2, φ3, and φ4, then F t It can also be expressed as

[0098] F t =f7(φ1,φ2,φ3,φ4) (19)

[0099] Therefore Figure 2 The system of equations for each time point can all be closed, and theoretically, the values ​​of φ1, φ2, φ3, and φ4 at that time can be solved.

[0100] E. Finally, solve the system of equations:

[0101] Due to the high degree of parameter coupling in the equation system, it is difficult to provide an analytical expression. To solve the above equation system, an iterative method can be used, that is, to traverse the value boundary range of (φ1,φ2,φ3,φ4) and check whether the equation system is satisfied until a set of (φ1,φ2,φ3,φ4) that satisfies the equation system is found, and then the values ​​of attitude and load of each floating body can be calculated.

[0102] Considering the large workload involved in calculating the hydrostatic pressure integration on the surface of the floating body, using an enumeration approach to traverse (φ1, φ2, φ3, φ4) at each time step would require significant computational power. Preferably, a surrogate model technique can be used to establish a relationship between (φ1, φ2, φ3, φ4) and F. p x BP F s x AS The correspondence is as follows:

[0103] (1) adopt appropriate sampling design method, design enough number of discrete points (φ1, φ2, φ3, φ4);

[0104] (2) for each discrete point, through hydrostatic pressure integral calculation to obtain the corresponding F p , x BP , F s , x AS ;

[0105] (3) using these discrete points and forecast value, complete interpolation in multidimensional space, establish (φ1, φ2, φ3, φ4) and F p , x BP , F s , x AS Corresponding relationship of proxy model;

[0106] (4) in the subsequent traversal (φ1, φ2, φ3, φ4), only call proxy model to carry out forecast calculation to F p , x BP , F s , x AS Can greatly shorten the calculation time, and can guarantee enough calculation accuracy.

[0107] The technical scheme of the present application is applied to the loading and unloading of vehicles on a roll-on / roll-off ship or a roll-on / roll-off boat.

[0108] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of the patent protection of the present application should be subject to the appended claims.

Claims

1. A method for predicting the load and motion of vehicles transferring between floating platforms, characterized in that, Specifically, the steps include the following: 1) Establish a geometric and physical model of multiple floating bodies connected by gangplanks. Based on the geometric and physical model and combined with the hydrostatic integral solution theory of floating state of floating bodies, construct a set of equations to determine the buoyancy, center of buoyancy and attitude of each floating body with the longitudinal tilt angle of each floating body and the slope of the gangplank as unknowns. 2) Obtain the initial time t0 of vehicle transfer, input the vehicle weight and location, and based on the geometric relationship, combine the equations of buoyancy, center of buoyancy and attitude of the floating body, and solve the relevant attitude, coordinates and load values ​​of each floating body at this time according to the force and moment balance equations. 3) Take the time step Δt, the initial time t0+Δt at the next moment of vehicle transfer, determine the position of the vehicle according to the vehicle speed, combine the equations of buoyancy, center of buoyancy and attitude of the floating body, and solve the relevant attitude, coordinate and load values ​​of each floating body at this time according to the force and moment balance equations. 4) Calculate the relevant attitude, coordinates, and load values ​​of each float at each time t0+n△t to obtain the time history values ​​of the float state, gangway angle, and load of relevant components of the float of interest; 5) Using the data obtained in steps 2) to 4), construct proxy models of the pitch angle and ramp slope of each float and the buoyancy and center of buoy position of each float using existing adaptive algorithms. These models are used to estimate the relevant attitude, coordinates, and load values ​​of each float under various vehicle driving conditions, serving as the basis for operational safety and feasibility analysis.

2. The method for predicting the load and motion of vehicles transferring between floating platforms according to claim 1, characterized in that, Step 1) Geometric and physical model establishment: Establish a two-dimensional model in which the load and motion are both within the longitudinal section of each float. Set various nodes on the model, including the center of gravity of each float, the center of buoyancy of the float, the center of gravity of the gangplank, the center of gravity of the vehicle, the two ends of the cable, and the two connection points of the gangplank. Establish constraints on the nodes in the model.

3. The method for predicting the load and motion of vehicles transferring between floating platforms according to claim 2, characterized in that, Step 1) Equation system construction: After the geometric physical model is established, the force analysis of the overlapping system in the geometric physical model is carried out according to the quasi-static method to establish the geometric relationship of the force. Based on the geometric relationship, if the longitudinal tilt angle and the ramp slope of any group of floats are known, the draft of the rib where the center of gravity of each float is located is obtained. By calculating the static pressure at each position on the surface of each float and then integrating, the magnitude of the buoyancy force on each float and the coordinate of the center of buoyancy are calculated, and the simultaneous equation system of the buoyancy force and the coordinate of the center of buoyancy of each float is obtained.

4. The method for predicting the load and motion of vehicles transferring between floating platforms according to claim 3, characterized in that, The proxy model construction steps in step 5) are as follows: A: The data obtained in steps 2) to 4) are discrete points of the floating body attitude value. Based on this, a sampling design method is used to design a sufficient number of discrete points of the floating body attitude value. B: For each discrete point in step A, the buoyancy and coordinate values ​​of each floating body are calculated by integrating the hydrostatic pressure. The calculation results are the predicted values. C: Using the discrete points obtained in step B and the calculated forecast values, perform interpolation in multidimensional space to establish a surrogate model.

5. The method for predicting the load and motion of vehicles transferring between floating platforms according to claim 4, characterized in that, The sampling design method is selected from one of the following: Latin hypercube design, Sobol design, or orthogonal experimental design.

6. The method for predicting the load and motion of vehicles transferring between floating platforms according to claim 4, characterized in that, The proxy model adopted is a typical single proxy model of the Kriging model, or a combination of different proxy models to form a combined proxy model.

7. An application of a method for predicting the load and motion of vehicles transferring between floating platforms, characterized in that, Used for loading, unloading, and transferring vehicles on roll-on / roll-off ships and small roll-on / roll-off boats.

8. The application of the load and motion prediction method for the inter-float gangway transfer vehicle according to claim 7, characterized in that, This includes safety assessment of vehicle transfer during loading and unloading operations on roll-on / roll-off ships and small roll-on / roll-off boats, design of support and guarantee schemes, and determination of operational capacity boundaries.

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