A method for ship motion simulation of wave coupling

Abstract

The application discloses a method for simulating ship wave coupling motion, which comprises the following steps: establishing a ship coordinate system, decomposing a ship roll angle, respectively establishing a ship four-degree-of-freedom motion model and a ship two-degree-of-freedom motion model, respectively solving the ship roll angle, completing the solution of the ship wave coupling parameters and outputting to a visual scene. The ship roll motion is decomposed into two parts, i.e., a roll motion caused by a sea wave and a roll motion caused by other forces, meanwhile, the ship pitch motion, the ship heave motion and the roll motion caused by the sea wave are calculated by obtaining the sea wave height values of five points, so that the system calculation burden is reduced under the premise of effectively making up the ship motion distortion under the condition of strong wind and waves, the method is easy to implement in engineering and the ship motion simulation precision under the condition of small wind and waves is not reduced.

Description

Technical Field

[0001] This invention belongs to the field of shipbuilding technology, and in particular relates to a method for simulating ship-wave coupling motion. Background Technology

[0002] Ship driving simulators, as platforms for crew driving training and assessment, are characterized by their economy, safety, and convenience, and play an increasingly important role in ship driving training and assessment. With the rapid development of technologies such as 3D visual simulation, video image fusion, ship motion simulation, and radar echo simulation, ship driving simulators have significantly improved in recent years in terms of physical realism, environmental realism, and behavioral realism, making the pilot's operating experience gradually closer to that of a real ship.

[0003] Ship motion simulation algorithms are the core of ship motion simulation and control, and one of the key technologies for reflecting the realism of ship driving simulator behavior. Typically, a six-degree-of-freedom motion model of the ship is established using either a separate model or a holistic model. Empirical formulas are used to simulate some parameters, and combined with external inputs, the ship's displacement and attitude are calculated. Then, referring to the results of actual sea trials, some parameters are corrected to ensure that the simulation results match the actual test results.

[0004] The above methods are effective for simulating straight-line and turning motions of ships, and the pilot's driving experience is close to that of a real ship, such as controlling the ship's movement by manipulating the engine telegraph and steering wheel under light sea conditions. However, the response to ship movement under heavy sea conditions is not good, and distortions may occur, such as the stern or one side of the bow being submerged by waves while the other side is suspended in the air. The main reason is that the wave generation algorithm in the ship driving simulator is relatively independent from the ship's six-degree-of-freedom motion model algorithm, and the wave and ship motion are not coupled, resulting in a weak sense of immersion in the visual experience of ship movement under heavy sea conditions. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for simulating ship-wave coupling motion.

[0006] To achieve the above-mentioned objectives, the technical solution provided by this invention patent is as follows:

[0007] A method for simulating ship-wave coupling motion, the method specifically includes the following steps:

[0008] The first step is to establish a ship motion coordinate system, which includes a hull coordinate system (xyz) and a fixed coordinate system (XYZ).

[0009] The second step is to determine the ship's attitude by establishing a ship coordinate system and to determine the ship's position by using a fixed coordinate system.

[0010] The third step is to initialize the ship parameters, establish a four-degree-of-freedom mathematical model of the ship's motion, and solve for the parameters of the ship's horizontal plane motion and roll motion, as well as the ship's roll angle.

[0011] The fourth step is to establish a mathematical model of the ship's two degrees of freedom motion to solve for the parameters of the ship's pitching and heave motions, as well as the ship's roll angle.

[0012] Fifth step, adjust the ship's roll angle. and Summation is performed to solve for the parameters of ship motion displacement and attitude under ship-wave coupling. These parameters are then output to the view as the initial motion displacement and attitude parameters of the ship at the next moment. Steps 3 and 4 are repeated to complete the next round of cyclic calculation, thus completing the coupling calculation of ship-wave coupled simulation motion.

[0013] In the first step above, the ship's coordinate system is established with the ship as the origin G, and the fixed coordinate system XYZ is established with the sea level as the reference. The forward velocity in the x-axis direction of the ship's coordinate system is set as u, the lateral velocity in the y-axis direction of the ship's coordinate system is set as v, the heave velocity in the z-axis direction of the ship's coordinate system is set as w, the roll angular velocity about the x-axis is set as p, the pitch angular velocity about the y-axis is set as q, and the yaw angular velocity about the z-axis is set as r.

[0014] The three-dimensional coordinates of the aforementioned vessel in the fixed coordinate system are (X0, Y0, Z0). The velocity components of the vessel along the X, Y, and Z axes of the fixed coordinate system are represented by U, V, and W, respectively, and obtained by differentiating the three-dimensional coordinates of the vessel, specifically X0' = U, Y0' = V, Z0' = W. The vessel's attitude is represented by the three Euler angles generated during the vessel's rotation, respectively... θ and ψ represent, where Let θ be the ship's roll angle, θ be the ship's pitch angle, and ψ be the ship's bow angle.

[0015] The ship's attitude is described in the above hull coordinate system xyz using velocities u, v, and w, and angular velocity vectors p, q, and r. In the fixed coordinate system XYZ, the position vector derivatives X0', Y0', and Z0', as well as the derivatives of the Euler angle vectors, are used. θ' and ψ' are used to describe the ship's position; the velocities u, v, and w and the angular velocity vectors p, q, and r are used in conjunction with... The specific relationship between θ' and ψ' is as follows:

[0016]

[0017]

[0018] in:

[0019]

[0020]

[0021] The initialization of ship parameters in the third step mentioned above specifically includes ship principal dimension parameters, propeller parameters, rudder parameters, wind parameters, current parameters, wave parameters, tugboat parameters, anchor chain parameters, cable parameters, and initial displacement and attitude parameters of the ship.

[0022] The four-degree-of-freedom mathematical model of the ship's motion established in the third step above includes the ship's horizontal plane motion and its roll motion. The parameters of the ship's horizontal plane motion and roll motion, as well as the ship's roll angle, are solved using this mathematical model. Specifically, using the formula:

[0023]

[0024]

[0025]

[0026]

[0027] Solve for u, v, r, and p1, and then use the fourth-order Runge-Kutta method to solve for X0, Y0, and X0 based on the solved u, v, r, and p1. and ψ; The torque on a ship other than the rolling moment caused by ocean waves;

[0028] Where X, Y and N, K are the external forces and torques acting on the hull; u, v, r, p are the forward velocity along the x-axis, the lateral velocity along the y-axis, the yaw rate about the z-axis, and the roll rate about the x-axis, respectively; m is the mass of the ship; m x and m y These are the additional masses in the x-axis and y-axis directions, respectively; I xx and I zz J represents the moment of inertia about the x-axis and z-axis, respectively; xx and J zz These represent the additional moments of inertia with respect to the x-axis and z-axis, respectively. The subscripts on the right-hand side of the formula have the following meanings: H represents the bare hull; P represents the propeller; R represents the rudder; A represents the wind; W1 and W2 represent the first-order and second-order wave forces, respectively; B represents the shore wall; L represents the mooring rope; T represents the tugboat; C represents the external force and moment exerted by the anchor chain on the hull; and the heeling moment K does not include the heeling moment generated by the waves, and p1 does not include the influence of the waves.

[0029] The fourth step above involves establishing a mathematical model of the ship's two degrees of freedom motion, including the ship's pitching and heave motions. This model is used to solve for the parameters of the ship's pitching and heave motions, as well as the ship's roll angle. Specifically, the process involves first obtaining the wave height values ​​at five points: midship, port side, starboard side, bow, and stern, and then using H... mid H le f t H right H bow and H poop This means that the roll angle of the hull after fitting the waves is calculated based on the wave height values ​​obtained at five points: midship, port side, starboard side, bow, and stern. The pitch angle θ and the vertical height Z of the ship's motion with the waves are calculated using the following formulas:

[0030]

[0031] θ=arcsin((H poop -H bow ) / L)

[0032] Z = (H poop +H mid +H bow ) / 3

[0033] Where B is the beam of the ship and L is the length of the ship; This refers to the rolling moment of the ship caused by the ocean waves.

[0034] The above-mentioned ship roll angle The parameters for ship motion displacement and attitude under wave coupling in step five specifically include X0, Y0, Z0, θ and ψ.

[0035] Based on the above technical solution, the method for ship-wave coupling simulation motion of this invention patent has achieved the following technical advantages through practical application:

[0036] 1. The present invention provides a method for simulating ship motion coupled with waves. This method decomposes the ship's rolling motion into two parts: the rolling motion caused by the waves and the rolling motion caused by other forces. At the same time, the ship's pitching motion, heave motion, and rolling motion caused by the waves are calculated by obtaining the wave height values ​​at five points. This method effectively compensates for the distortion of ship motion under high wind and wave conditions, reduces the computational burden of the system, is easy to implement in engineering, and does not reduce the accuracy of ship motion simulation under low wind and wave conditions. Attached Figure Description

[0037] Figure 1This is a flowchart of the ship-wave coupling simulation motion method in the present invention.

[0038] Figure 2 This is a ship motion diagram before wave coupling in a method for simulating ship-wave coupling motion according to the present invention.

[0039] Figure 3 This is a ship motion diagram after wave coupling in a method for simulating ship-wave coupling motion according to the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific examples shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0041] like Figure 1 The present invention pertains to a method for simulating ship-wave coupling motion, which specifically includes the following steps:

[0042] The first step is to establish a ship motion coordinate system, which includes a hull coordinate system (xyz) and a fixed coordinate system (XYZ).

[0043] The second step is to determine the ship's attitude by establishing a ship coordinate system and to determine the ship's position by using a fixed coordinate system.

[0044] The third step is to initialize the ship parameters, establish a four-degree-of-freedom mathematical model of the ship's motion, and solve for the parameters of the ship's horizontal plane motion and roll motion, as well as the ship's roll angle.

[0045] The fourth step is to establish a mathematical model of the ship's two degrees of freedom motion to solve for the parameters of the ship's pitching and heave motions, as well as the ship's roll angle.

[0046] Fifth step, adjust the ship's roll angle. and The parameters of the ship's motion displacement and attitude under the ship-wave coupling are summed to obtain the parameters, and then output as the initial motion displacement and attitude parameters of the ship at the next moment to the view. The third and fourth steps are repeated to complete the next round of calculation, thus completing the coupling calculation of the ship-wave coupled simulation motion. By coupling the wave generation algorithm in the ship driving simulator with the ship's six-degree-of-freedom motion model algorithm, the ship motion distortion is reduced, and the effect of ship driving simulation is improved.

[0047] In the first step above, the ship's coordinate system is established with the ship as the origin G, and the fixed coordinate system XYZ is established with the sea level as the reference. The forward velocity in the x-axis direction of the ship's coordinate system is set as u, the lateral velocity in the y-axis direction of the ship's coordinate system is set as v, the heave velocity in the z-axis direction of the ship's coordinate system is set as w, the roll angular velocity about the x-axis is set as p, the pitch angular velocity about the y-axis is set as q, and the yaw angular velocity about the z-axis is set as r.

[0048] The three-dimensional coordinates of the aforementioned vessel in the fixed coordinate system are (X0, Y0, Z0). The velocity components of the vessel along the X, Y, and Z axes of the fixed coordinate system are represented by U, V, and W, respectively, and obtained by differentiating the three-dimensional coordinates of the vessel, specifically X0' = U, Y0' = V, Z0' = W. The vessel's attitude is represented by the three Euler angles generated during the vessel's rotation, respectively... θ and ψ represent, where Let θ be the ship's roll angle, θ be the ship's pitch angle, and ψ be the ship's bow angle.

[0049] The ship's attitude is described in the above hull coordinate system xyz using velocities u, v, and w, and angular velocity vectors p, q, and r. In the fixed coordinate system XYZ, the position vector derivatives X0', Y0', and Z0', as well as the derivatives of the Euler angle vectors, are used. θ' and ψ' are used to describe the ship's position; the velocities u, v, and w and the angular velocity vectors p, q, and r are used in conjunction with... The specific relationship between θ' and ψ' is as follows:

[0050]

[0051]

[0052] in:

[0053]

[0054]

[0055] The initialization of ship parameters in the third step mentioned above specifically includes ship principal dimension parameters, propeller parameters, rudder parameters, wind parameters, current parameters, wave parameters, tugboat parameters, anchor chain parameters, cable parameters, and initial displacement and attitude parameters of the ship.

[0056] The four-degree-of-freedom mathematical model of the ship's motion established in the third step above includes the ship's horizontal plane motion and its roll motion. The parameters of the ship's horizontal plane motion and roll motion, as well as the ship's roll angle, are solved using this mathematical model. Specifically, using the formula:

[0057]

[0058]

[0059]

[0060]

[0061] Solve for u, v, r, and p1, and then use the fourth-order Runge-Kutta method to solve for X0, Y0, and X0 based on the solved u, v, r, and p1. and ψ; The torque on a ship other than the rolling moment caused by ocean waves;

[0062] Where X, Y and N, K are the external forces and torques acting on the hull; u, v, r, p are the forward velocity along the x-axis, the lateral velocity along the y-axis, the yaw rate about the z-axis, and the roll rate about the x-axis, respectively; m is the mass of the ship; m x and m y These are the additional masses in the x-axis and y-axis directions, respectively; I xx and I zz J represents the moment of inertia about the x-axis and z-axis, respectively; xx and J zz These represent the additional moments of inertia with respect to the x-axis and z-axis, respectively. The subscripts on the right-hand side of the formula have the following meanings: H represents the bare hull; P represents the propeller; R represents the rudder; A represents the wind; W1 and W2 represent the first-order and second-order wave forces, respectively; B represents the shore wall; L represents the mooring rope; T represents the tugboat; C represents the external force and moment exerted by the anchor chain on the hull; and the heeling moment K does not include the heeling moment generated by the waves, and p1 does not include the influence of the waves.

[0063] The fourth step above involves establishing a mathematical model of the ship's two degrees of freedom motion, including the ship's pitching and heave motions. This model is used to solve for the parameters of the ship's pitching and heave motions, as well as the ship's roll angle. Specifically, the process involves first obtaining the wave height values ​​at five points: midship, port side, starboard side, bow, and stern, and then using H... mid H left H right H bow and H poop This means that the roll angle of the hull after fitting the waves is calculated based on the wave height values ​​obtained at five points: midship, port side, starboard side, bow, and stern. The pitch angle θ and the vertical height Z of the ship's motion with the waves are calculated using the following formulas:

[0064]

[0065] θ=arcsin((H poop -H bow ) / L)

[0066] Z = (H poop +H mid +H bow ) / 3

[0067] Where B is the width of the ship and L is the length of the ship; The rolling moment of the ship is caused by the waves. The ship's rolling motion is decomposed into two parts: the rolling motion caused by the waves and the rolling motion caused by other forces. At the same time, the ship's pitching motion, heave motion and rolling motion caused by the waves are calculated by obtaining the wave height values ​​at five points. Under the premise of effectively compensating for the distortion of ship motion under high wind and wave conditions, the system's computational burden is reduced, which is easy to implement in engineering and does not reduce the simulation accuracy of ship motion under low wind and wave conditions.

[0068] The above-mentioned ship roll angle The parameters for ship motion displacement and attitude under wave coupling in step five specifically include X0, Y0, Z0, θ and ψ.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for simulating ship-wave coupling motion, characterized in that, The method specifically includes the following steps: The first step is to establish a ship motion coordinate system, which includes a hull coordinate system (xyz) and a fixed coordinate system (XYZ). The second step is to determine the ship's attitude by establishing a ship coordinate system and to determine the ship's position by using a fixed coordinate system. The third step is to initialize the ship parameters, establish a four-degree-of-freedom mathematical model of the ship's motion, and solve for the parameters of the ship's horizontal plane motion and roll motion, as well as the ship's roll angle. ; The four-degree-of-freedom mathematical model of the ship's motion established in the third step includes the ship's horizontal plane motion and its roll motion. The parameters of the ship's horizontal plane motion and roll motion, as well as the ship's roll angle, are solved using this mathematical model. Specifically, using the formula: ， Solve for u, v, r, and p1, and then use the fourth-order Runge-Kutta method to solve for X0, Y0, and X0 based on the solved u, v, r, and p1. and ; The torque on a ship other than the rolling moment caused by ocean waves; Where X, Y and N, K are the external forces and torques acting on the hull; u, v, r, p are the forward velocity along the x-axis, the lateral velocity along the y-axis, the yaw rate around the z-axis, and the roll rate around the x-axis, respectively; m is the mass of the ship. and These are the additional masses in the x-axis and y-axis directions, respectively; and These are the moments of inertia about the x-axis and z-axis, respectively. and These are the additional moments of inertia with respect to the x-axis and z-axis, respectively; the subscripts on the right-hand side of the formula have the following meanings: H is the bare hull; P is the propeller; R is the rudder; A is the wind; W1 and W2 are the first-order wave force and the second-order wave force, respectively; B is the shore wall; L is the cable; T is the tugboat; C is the external force and moment of the anchor chain acting on the hull; at the same time, the heeling moment K does not include the heeling moment generated by the waves on the ship, and p1 does not include the effect of the waves; The fourth step is to establish a mathematical model of the ship's two degrees of freedom motion to solve for the parameters of the ship's pitching and heave motions, as well as the ship's roll angle. ; The fourth step, establishing a two-degree-of-freedom mathematical model of the ship's motion, includes the ship's pitching and heave motions. The parameters of the ship's pitching and heave motions, as well as the ship's roll angle, are solved using this model. Specifically, this involves first obtaining the wave height values ​​at five points: midship, port side, starboard side, bow, and stern, and then using... , , , and This means that the roll angle of the hull after fitting the waves is calculated based on the wave height values ​​obtained at five points: midship, port side, starboard side, bow, and stern. Pitch angle The vertical height Z of the ship's hull as it moves with the waves is calculated using the following formula: ， Where B is the width of the ship and L is the length of the ship. The rolling moment of the ship caused by the ocean waves; Fifth step, adjust the ship's roll angle. and Summation is performed to solve for the parameters of ship motion displacement and attitude under ship-wave coupling. These parameters are then output to the view as the initial motion displacement and attitude parameters of the ship at the next moment. Steps 3 and 4 are repeated to complete the next round of cyclic calculation, thus completing the coupling calculation of ship-wave coupled simulation motion.

2. The method for ship-wave coupling simulation motion according to claim 1, characterized in that, In the first step, the ship's coordinate system is established with the ship as the origin G, and the fixed coordinate system XYZ is established with the sea level as the reference. The forward velocity in the x-axis direction of the ship's coordinate system is set as u, the lateral velocity in the y-axis direction of the ship's coordinate system is set as v, the heave velocity in the z-axis direction of the ship's coordinate system is set as w, the roll angular velocity about the x-axis is set as p, the pitch angular velocity about the y-axis is set as q, and the yaw angular velocity about the z-axis is set as r.

3. The method for ship-wave coupling simulation motion according to claim 2, characterized in that, The ship's three-dimensional coordinates in the fixed coordinate system are (X0, Y0, Z0). The ship's velocity components along the X, Y, and Z axes of the fixed coordinate system are represented by U, V, and W, respectively, and are obtained by differentiating the ship's three-dimensional coordinates. Specifically, X0... ＇ =U,Y0 ＇ =V,Z0 ＇ =W, where the ship's attitude is defined by the three Euler angles generated during the ship's rotation, respectively... , and It means that among them The ship's roll angle, For the ship's pitch angle, The bow angle of the ship.

4. The method for ship-wave coupling simulation motion according to claim 3, characterized in that, The ship's attitude is described in the hull coordinate system xyz using velocities u, v, and w and angular velocity vectors p, q, and r. In the fixed coordinate system XYZ, the position vector derivative X0 is used. ＇ Y0 ＇ and Z0 ＇ and the derivative of Euler angle vectors ＇ , ＇ and ＇ To describe the ship's position; the velocities u, v, and w and the angular velocity vectors p, q, and r are used in conjunction with... ＇ , ＇ and ＇ The specific solution relation is as follows: ， in: ， 。 5. The method for ship-wave coupling simulation motion according to claim 1, characterized in that, The initialization of ship parameters in the third step specifically includes ship principal dimension parameters, propeller parameters, rudder parameters, wind parameters, current parameters, wave parameters, tugboat parameters, anchor chain parameters, cable parameters, and initial displacement and attitude parameters of the ship.

6. The method for ship-wave coupling simulation motion according to claim 1, characterized in that, The ship's roll angle = + The parameters for ship motion displacement and attitude under wave coupling in step five specifically include X0, Y0, Z0, , and .

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