Dynamic modeling method of vector propulsion AUV (Autonomous Underwater Vehicle)

Abstract

The invention discloses a dynamic modeling method for a vector propulsion AUV (Autonomous Underwater Vehicle), which relates to the field of vector propulsion AUVs, and comprises the following steps: respectively acquiring vector propulsion performances of a vector propeller in the vector propulsion AUV under different operation conditions under the action of different fluid parameters through a CFD (Computational Fluid Dynamics) simulation method; then a relational expression between the thrust coefficient of the vector propeller and the fluid parameters is obtained through fitting, a six-degree-of-freedom kinetic equation is constructed through the hydrodynamic parameters of the vector propulsion AUV and the thrust coefficient of the vector propeller, and the coupling influence of multiple factors on vector propulsion can be fully considered so that the vector propulsion characteristic can be accurately represented. The established six-degree-of-freedom kinetic equation can describe the kinetic characteristics of the vector propulsion AUV more accurately, and a kinetic model for the vector propulsion AUV is established in combination with a kinematic equation, so that the motion process of the vector propulsion AUV can be accurately forecasted.

Description

Technical Field

[0001] The present application relates to the field of vector-propelled AUV, and in particular to a dynamic modeling method of a vector-propelled AUV. Background Art

[0002] An autonomous underwater vehicle (AUV) is a device or tool that can assist or replace humans to complete underwater tasks. It can carry various equipment and payloads and perform tasks through autonomous control. Traditional AUVs are under-actuated control systems, and their control input dimensions are less than their motion freedom dimensions. They are mainly used in cruise-type operations such as cargo transportation, search, and exploration. The control method is simple, but the control performance of under-actuated AUVs will be significantly reduced at low speeds. Therefore, more and more practices will add vector thrusters to the rear of the AUV to form a vector-propelled AUV, so that higher maneuverability can be achieved without adding more dimensional control inputs.

[0003] Compared with the traditional underactuated AUV, the vector thrust generated by the vector thruster needs to be considered when controlling the motion of the vector propulsion AUV. The common practice is to simplify the vector thruster into a constant thrust to perform an ideal deflection at a certain deflection angle, and describe the vector thrust by a simple trigonometric function. However, the force and torque generated by the vector thruster actually have obvious coupling characteristics. The traditional simplified approach ignores the coupling characteristics of vector propulsion, resulting in an inaccurate description of the dynamics of the vector propulsion AUV by the established model, which affects the accurate prediction of the motion process of the vector propulsion AUV. Summary of the invention

[0004] In view of the above problems and technical requirements, this application proposes a dynamic modeling method for a vector-propelled AUV. The technical solution of this application is as follows:

[0005] A dynamic modeling method for a vector-propelled AUV, the dynamic modeling method comprising:

[0006] The hydrodynamic parameters of the vector-propelled AUV are obtained through CFD simulation method;

[0007] The vector propulsion performance of the vector thruster in the vector propulsion AUV under different operating conditions and under the action of different fluid parameters is obtained by CFD simulation method. The vector propulsion performance includes thruster thrust and thruster torque.

[0008] According to the vector propulsion performance of the vector thruster under different operating conditions and under the action of different fluid parameters, the thrust coefficient K of the vector thruster is obtained by fitting. p Relationship with fluid parameters;

[0009] Hydrodynamic parameters of vector-propelled AUV and thrust coefficient K of vector thruster p , the six-degree-of-freedom dynamic equations related to the working parameters of the vector thruster and the fluid parameters are constructed Where P = m(v + ω × r c ) is the momentum of the vector-propelled AUV, L = Iω + r c ×mv is the momentum of the vector-propelled AUV, m is the mass of the vector-propelled AUV, v is the velocity vector of the center of buoyancy of the vector-propelled AUV in the ground coordinate system, ω is the rotational angular velocity vector of the vector-propelled AUV in the ground coordinate system, r c is the vector radius from the center of mass of the vector-propelled AUV to the center of buoyancy, I represents the inertia tensor matrix of the vector-propelled AUV about the center of buoyancy; F represents the vector of all external forces on the vector-propelled AUV in the body coordinate system, M represents the vector of all external torques on the vector-propelled AUV in the body coordinate system; all external forces on the vector-propelled AUV include hydrodynamic force, buoyancy force and thruster thrust, all external torques on the vector-propelled AUV include hydrodynamic torque, buoyancy torque and thruster thrust, vector propulsion performance and thrust coefficient K p Related to the operating parameters of the vector thruster;

[0010] The motion control of the vector propulsion AUV is carried out by using the six-degree-of-freedom dynamic equation combined with the kinematic equation of the vector propulsion AUV;

[0011] Among them, the body coordinate system Oxyz takes the buoyancy center of the vector-propelled AUV as the coordinate origin O, the navigation direction of the vector-propelled AUV is the positive x direction, the direction pointing to the port side of the vector-propelled AUV is the positive y direction, and the positive z direction is perpendicular to the xy plane and upward.

[0012] The beneficial technical effects of this application are:

[0013] The present application discloses a dynamic modeling method for a vector propulsion AUV. The method obtains the vector propulsion performance of a vector propulsion device in the vector propulsion AUV under different operating conditions when subjected to different fluid parameters by a CFD simulation method, and then obtains the relationship between the thrust coefficient of the vector propulsion device and the fluid parameters by fitting. The hydrodynamic parameters of the vector propulsion AUV and the thrust coefficient of the vector propulsion device are used to construct a six-degree-of-freedom dynamic equation, so that the six-degree-of-freedom dynamic equation is not only related to the operating parameters of the vector propulsion device, but also to the fluid parameters. The coupling effects of various factors on the vector propulsion can be fully considered to accurately characterize the vector propulsion characteristics. The constructed six-degree-of-freedom dynamic equation can more accurately describe the dynamic characteristics of the vector propulsion AUV. A precise dynamic model can be established in combination with the kinematic equation, thereby optimizing the accuracy of the prediction of the motion process of the vector propulsion AUV.

[0014] The dynamics modeling method involves the construction method of dynamic equations and kinematic equations, which can be applied to different types of vector thrusters, and can simultaneously ensure the accurate description of vector propulsion performance and the modeling calculation efficiency, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the relationship between the three coordinate systems involved in the vector propulsion AUV.

[0016] Figure 2 It is a method flow chart of a kinetic modeling method according to an embodiment of the present application. DETAILED DESCRIPTION

[0017] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0018] This application discloses a dynamic modeling method for a vector-propelled AUV. The accurate prediction of the motion process of an underwater device and further motion control often rely on the dynamic equations and kinematic equations of the underwater device. Therefore, accurately constructing the dynamic equations and kinematic equations of a vector-propelled AUV is the basis for improving the control accuracy and control efficiency of the vector-propelled AUV. This application is introduced as follows:

[0019] 1. Kinematic equations of vector propulsion AUV

[0020] Please refer to Figure 1 The coordinate system diagram shown in the figure shows that the vector propulsion AUV involves three different coordinate systems when working, including the ground coordinate system O e x e y e z e , body coordinate system Oxyz and velocity coordinate system Ox1y1z1, which are introduced as follows:

[0021] (1) Ground coordinate system O e x e y e z e It is fixed to the ground and is used to describe the position and motion of the vector-propelled AUV in space relative to the ground. The ground coordinate system O e x e y e z e Generally, the starting point of the vector-propelled AUV can be selected as the coordinate origin O e Establish, this application is for the ground coordinate system O e x e y e z e The three-axis directions are not limited, such as Figure 1 Take O e x e ze Parallel to the horizontal plane, y e Take the vertical direction upward as an example.

[0022] (2) The body coordinate system Oxyz is fixedly connected to the vector-propelled AUV and remains relatively stationary with the vector-propelled AUV. The body coordinate system Oxyz is used to describe the posture of the vector-propelled AUV. The body coordinate system Oxyz takes the buoyancy center of the vector-propelled AUV as the coordinate origin O, the navigation direction of the vector-propelled AUV as the positive x direction, the direction pointing to the port side of the vector-propelled AUV as the positive y direction, and the positive z direction perpendicular to the xy plane and upward.

[0023] (3) The velocity coordinate system Ox1y1z1 is also fixedly connected to the vector-propelled AUV. The velocity coordinate system Ox1y1z1 is used to refer to the movement speed of the vector-propelled AUV. The velocity coordinate system Ox1y1z1 takes the buoyancy center of the vector-propelled AUV as the coordinate origin O and is used to describe the instantaneous speed of the vector-propelled AUV.

[0024] The velocity coordinate system Ox1y1z1 is also fixed to the vector propulsion AUV, and the origin of the velocity coordinate system Ox1y1z1 is also selected at the buoyancy center of the vector propulsion AUV. The velocity coordinate system Ox1y1z1 is used to describe the instantaneous velocity of the vector propulsion AUV. The Ox1 axis points to the velocity vector direction of the vector propulsion AUV, also known as the velocity axis. Oy1 is located in the longitudinal symmetry plane of the vector propulsion AUV, perpendicular to the Ox1 axis and pointing upward. The Oz1 axis is perpendicular to the plane formed by the Ox1 axis and the Oy1 axis, forming a right-handed system.

[0025] Ground coordinate system O e x e y e z e There is also a conversion relationship between the body coordinate system Oxyz and the velocity coordinate system Ox1y1z1. There is a clear angle definition between different coordinate systems. The coordinate conversion matrix can be obtained by using the azimuth angles between the coordinate axes. The positive and negative conversion matrices between the coordinate systems are transposed matrices:

[0026] (a) The three azimuth angles of the body coordinate system relative to the ground coordinate system are the attitude angles of the vector-propelled AUV. The attitude angles of the vector-propelled AUV include the pitch angle θ, the yaw angle ψ, and the roll angle φ. The pitch angle θ is the angle between the x-axis of the body coordinate system and the x-axis of the ground coordinate system. e The yaw angle ψ is the angle between the y axis of the body coordinate system and the y axis of the ground coordinate system. e The roll angle φ is the angle between the z-axis of the body coordinate system and the z-axis of the ground coordinate system. e The ground coordinate system O can be constructed using the pitch angle θ, yaw angle ψ, and roll angle φ. e x e y e z eCoordinate transformation matrix to body coordinate system Oxyz for:

[0027]

[0028] (b) The attack angle α and sideslip angle β of the vector-propelled AUV are used to describe the azimuthal relationship between the motion vector and the AUV attitude during motion.

[0029] The angle between the projection of the x1 axis of the velocity coordinate system Ox1y1z1 on the xOy plane in the body coordinate system Oxyz and the x axis of the body coordinate system is the angle of attack α of the vector-propelled AUV. When the x1 axis is biased downward, the angle of attack α is positive. The angle between the x1 axis of the velocity coordinate system Ox1y1z1 and the xOy plane in the body coordinate system Oxyz is the sideslip angle β of the vector-propelled AUV. When the x1 axis is biased to the right, the sideslip angle β is positive. The coordinate transformation matrix from the body coordinate system Oxyz to the velocity coordinate system Ox1y1z1 can be constructed using the angle of attack α and the sideslip angle β. for:

[0030]

[0031] (c) The velocity coordinate system Ox1y1z1 is relative to the ground coordinate system O e x e y e z e The azimuth angle is the ballistic angle of the vector-propelled AUV. The ballistic angle of the vector-propelled AUV includes the ballistic inclination angle Θ, the ballistic deviation angle Ψ, and the tilt angle Φ: The ballistic inclination angle Θ is the angle between the x1 axis of the velocity coordinate system Ox1y1z1 and the ground coordinate system x e The ballistic deflection angle Ψ is the angle between the y1 axis of the velocity coordinate system Ox1y1z1 and the y axis of the ground coordinate system e The inclination angle Φ is the angle between the z1 axis of the velocity coordinate system Ox1y1z1 and the z axis of the ground coordinate system e The ground coordinate system O can be constructed using the trajectory inclination angle Θ, trajectory deviation angle Ψ, and tilt angle Φ. e x e y e z e Coordinate transformation matrix to velocity coordinate system Ox1y1z1 for:

[0032]

[0033] The above three coordinate transformation matrices can be used to transform coordinates between the three coordinate systems, and one of the coordinate transformation matrices can be expressed using the other two coordinate transformation matrices. The same applies to other cases.

[0034] The kinematic equation of the vector-propelled AUV is constructed to describe the motion process of the vector-propelled AUV, and the motion process of the vector-propelled AUV is described using its ground coordinate system O e x e y e z e The present application uses the position coordinates of the buoyancy center of the vector-propelled AUV to refer to the position coordinates of the entire vector-propelled AUV. The position coordinates of the buoyancy center of the vector-propelled AUV are in the ground coordinate system O e x e y e z e Denoted as (x e ,y e ,z e ),based on Figure 1 The ground coordinate system O shown e x e y e z e , x e ,y e 、z e They represent the horizontal displacement, diving depth and lateral displacement of the vector-propelled AUV respectively. Similarly, this application uses the velocity at the buoyancy center of the vector-propelled AUV to refer to the overall motion speed of the vector-propelled AUV. The components of the velocity vector v at the buoyancy center of the vector-propelled AUV in the three directions of the ground coordinate system are (v ex ,v ey ,v ez ).

[0035] Using the coordinate transformation matrix The components of the velocity vector v at the center of buoyancy of the vector-propelled AUV in the three directions of the body coordinate system Oxyz (v x ,v y ,v z ) is expressed as:

[0036]

[0037] in, is x e The derivative with respect to time and other parameters are expressed similarly.

[0038] In addition, it can be determined that the angle of attack α and sideslip angle β of the vector propulsion AUV can be expressed as:

[0039]

[0040] The position coordinates of the center of buoyancy of the vector-propelled AUV (x e ,y e ,z e) The curve that changes with time is the motion trajectory of the vector-propelled AUV. Therefore, by substituting it into the ground coordinate system, the motion trajectory of the vector-propelled AUV at the buoyancy center can be described as:

[0041]

[0042] The rotation of the vector-propelled AUV is described by the attitude angle. The rotation angular velocity vector ω of the vector-propelled AUV is in the ground coordinate system O e x e y e z e There are:

[0043]

[0044] Project the attitude angle vector to the body coordinate system, and define the components of the rotational angular velocity vector ω of the vector-propelled AUV in the three directions of the body coordinate system as (ω x ,ω y ,ω z ), then:

[0045]

[0046] Therefore, the kinematic equations of the vector-propelled AUV can be constructed as follows:

[0047]

[0048] 2. Dynamic equations of vector-propelled AUV

[0049] Based on the momentum theorem and the definition of angular momentum, it can be determined that the six-degree-of-freedom dynamic equation can be expressed as:

[0050]

[0051] Where P is the momentum of the vector-propelled AUV and can be written as:

[0052] P=mv e

[0053] Where m is the mass of the vector-propelled AUV, v e is the velocity vector of the center of mass of the vector-propelled AUV in the ground coordinate system, and is:

[0054] v e =v+ω×r c

[0055] In the above formula, r c is the radius vector from the center of mass of the vector-propelled AUV to the center of buoyancy, and v is the velocity vector at the center of buoyancy of the vector-propelled AUV.

[0056] So we have:

[0057] P=m(v+ω×r c )

[0058] In the six-degree-of-freedom dynamics equation, L is the momentum of the vector-propelled AUV and:

[0059] L=Iω+r c ×mv

[0060] In the above formula, I represents the inertia tensor matrix of the vector-propelled AUV about the center of buoyancy, which is written as:

[0061]

[0062] In the formula, J xy =J yx , J xz =J zx , J zy =J yz And they are all inertia products. The vector-propelled AUV with rotationally symmetrical shape does not take inertia products into account, so we have The inertia tensor matrix I is an inherent property of the vector-propelled AUV and can be obtained in advance through measurement or calculation and is a known quantity.

[0063] The momentum P and angular momentum L of the vector-propelled AUV are expressed in the body coordinate system Oxyz as:

[0064]

[0065] is the radius r from the center of mass to the center of buoyancy of the vector-propelled AUV c The components of the three directions in the body coordinate system are (x c ,y c , z c ) is an antisymmetric matrix, and there is E 3×3 It is the 3*3 identity matrix.

[0066] F represents the vector of all external forces on the vector-propelled AUV in the body coordinate system, and M represents the vector of all external torques on the vector-propelled AUV in the body coordinate system. In order to accurately construct the six-degree-of-freedom dynamic equations of the vector-propelled AUV, accurate characterization of F and M is the key. All external forces and external torques on the vector-propelled AUV correspond to each other, mainly including three categories: All external forces on the vector-propelled AUV include hydrodynamic force, gravity and buoyancy F ΔB and thruster thrust F THR The total external torque on the vector propulsion AUV includes the hydrodynamic torque, the gravity torque M ΔB and thrust torque M THRThe traditional approach simplifies the vector thruster into a constant thrust and performs an ideal deflection at a certain deflection angle, resulting in inaccurate characterization of the thrust and thrust torque of the thruster, which is the main reason affecting the current control performance. Therefore, the focus of this application is to accurately characterize the thrust and thrust torque of the vector propulsion AUV, as described below:

[0067] 1. The thrust force F exerted on the vector propulsion AUV THR and thrust torque M THR Characterization

[0068] Vector propulsion performance and thrust coefficient K of vector thruster p It is related to the working parameters of the vector thruster, and the thruster thrust F generated by the center of buoyancy of the vector thruster AUV THR and thrust torque M THR can be expressed as:

[0069]

[0070]

[0071] in, is the dimensionless thrust coefficient of the vector thruster, K Tpx , K Tpy , K Tpz They are thrust coefficient K p The force component coefficients in the three directions of the body coordinate system, K Qpx , K Qpy , K Qpz They are thrust coefficient K p The torque component coefficients in the three directions of the body coordinate system. D is the diameter of the vector thruster, L AC It is the distance from the center of the vector thruster in the vector propulsion AUV to the buoyancy center of the vector propulsion AUV. These two parameters are related to the structure of the vector propulsion. The operating parameters of the vector thruster include the speed n of the vector thruster.

[0072] From the above expression, it can be determined that the key to accurately characterize the vector propulsion performance of the vector thruster is to obtain the thrust coefficient K of the vector thruster considering the coupling characteristics. p , and the thrust coefficient K of the vector thruster is p Affected by many factors, mainly affected by the operating conditions of the vector thruster and the effect of the fluid parameters, this application first obtains the vector thruster performance of the vector thruster in the vector thruster AUV under different operating conditions and the effect of different fluid parameters by CFD simulation method, and then according to the vector thruster performance under different operating conditions and the effect of different fluid parameters, the thrust coefficient K of the vector thruster can be fitted.p The relationship between the thrust coefficient K and the fluid parameters is: p It is related to the fluid parameters, so that the characterized vector propulsion performance is also related to the fluid parameters, so that the constructed six-degree-of-freedom dynamic equation is not only related to the operating parameters of the vector thruster, but also related to the fluid parameters of the fluid environment, so that the six-degree-of-freedom dynamic equation can fully consider the influence of various influencing factors on the vector propulsion performance.

[0073] Specifically, obtaining the vector propulsion performance of the vector thruster under different operating conditions when subjected to different fluid parameters includes:

[0074] Get the vector thruster in open water at different vector deflection angles δ e Below, different vector deflection angles δ r Under different speed coefficients and different vector deflection angles δ e With δ r Vector propulsion performance in coupled state.

[0075] The control parameter of the vector thruster is defined as the horizontal deflection angle of the auxiliary duct in the vertical axis direction as δ e , the vertical deflection angle of the auxiliary duct in the horizontal axis direction is δ r , when the auxiliary guide tube in the vertical axis direction deflects downward, e is positive, looking forward from behind the AUV, when the secondary duct in the horizontal direction deflects to the right, δ r In the body coordinate system Oxyz, the Oy axis is called the vertical axis and the Oz axis is called the horizontal axis.

[0076] Get the vector thruster in the independent maneuvering state at different lateral and longitudinal flow angles α obl Under different vector deflection angles δ e Below, different vector deflection angles δ r Under different speed coefficients and different vector deflection angles δ e With δ r Vector propulsion performance in coupled state.

[0077] Obtain the vector propulsion of the AUV after the vector thruster is assembled on the AUV body and performs maneuvering under straight and oblique flow conditions at different vector deflection angles δ e Below, different vector deflection angles δ r Under different speed coefficients and different vector deflection angles δ e With δ r Vector propulsion performance in coupled state.

[0078] The vector propulsion performance obtained by simulation under each operating condition under the action of a set of fluid parameters includes thrust and thrust torque, from which the thrust coefficient K can be fitted.p The relationship between the influencing factors includes fluid parameters and propeller parameters. The fluid parameters here include the horizontal and vertical oblique flow angle α obl and the advance coefficient J. The thruster parameters include the vector deflection angle δ e and δ r , the installation status of the vector thruster and the AUV body. These fluid parameters have an impact on the thrust coefficient K p The influence of is different, and the thrust coefficient of the vector thruster finally fitted can be written as:

[0079]

[0080] (1) K pJ It is a function related to the advance coefficient J obtained by fitting, which is used to characterize the effect of the advance coefficient J on the thrust coefficient K. p On the one hand, during navigation, the existence of the AUV body will cause the overall deviation of the advance coefficient. Therefore, considering the influence of the AUV body on the wake field of the vector thruster, the wake fraction w can be used to correct the advance coefficient J to J w =J(1-w).

[0081] On the other hand, during navigation, the advance coefficient is maintained near the self-propulsion point, and there will be a small fluctuation during maneuvering. Therefore, within the error range, it can be considered that the advance coefficient varies in a small range near the self-propulsion point. p The influence of linear processing near the self-propelled point can be starved to K pJ =A J J w +Β J , thus obtaining K pJ The relationship between the speed coefficient J is:

[0082] K pJ =A J J(1-w)+Β J

[0083] Among them, A J and Β J are the parameter matrices obtained by fitting. In this embodiment, the calculation results of the AUV rear thruster are compared with the calculation results of the open water setting, and w=0.1 is taken.

[0084] (2) is the fitting result with the vector deflection angle δ e With δ r The related term, the vector deflection angle δ e With δ r Thrust coefficient K pThe influence of K is obviously coupled, so it cannot be pJ It is also characterized by a linear function, but is based on the fitting result and the vector deflection angle δ e With δ r The related interpolation surface f δ To characterize What you get f δ (δ e ,δ r ) represents the interpolation surface f obtained by fitting δ The deflection angle δ of the vector e With δ r The corresponding value.

[0085] (3) is the fitting result with the deflection angle δ and the oblique flow angle α obl The related terms are the deflection angle δ and the oblique flow angle α obl Thrust coefficient K p The influence of is also obviously coupled, so the deflection angle δ and the oblique flow angle α can be obtained based on the fitting. obl The related interpolation surface f obl To characterize

[0086] The oblique flow has different effects under different deflection angles. The oblique flow is decomposed into the horizontal and vertical components of the body coordinate system. The effects of the oblique flow angle and the deflection of the auxiliary duct in each direction are considered separately, and the oblique flow effects in each direction are taken to be independent within the error range. obl The oblique flow angle component α in the y direction of the body coordinate system obly and the oblique flow angle α obl The oblique flow angle component α in the z direction of the body coordinate system oblz It is expressed as:

[0087]

[0088] Among them, L AC It is the distance from the center of the vector thruster in the vector propulsion AUV to the center of buoyancy of the vector propulsion AUV.

[0089] After decomposition in two directions, the oblique flow angle component under different deflection angles δ in each direction has an effect on the thrust coefficient K p The influence of is used to establish the interpolation surface f in the form of dimensionless coefficient increments obl Using this interpolation surface f obl The oblique flow angle component α in the y direction of the body coordinate system can be expressed as obly The fluid coefficient increment caused by obl (α obly ,δ e), the oblique flow angle component α in the z direction of the body coordinate system oblz The fluid coefficient increment caused by obl (α oblz ,δ r ). obl (α obly ,δ e ) represents the interpolation surface f obtained by fitting obl The deflection angle δ and the oblique flow angle component α obly The corresponding value, f obl (α oblz ,δ r ) represents the interpolation surface f obtained by fitting obl The deflection angle δ and the oblique flow angle component α oblz The corresponding value.

[0090] Since the interpolation surface f obl It is defined with respect to the deflection angle δ. After interpolation, the oblique flow angle component α in the y direction of the body coordinate system needs to be obly The fluid coefficient increment caused by is converted to the z direction of the body coordinate system, and the conversion matrix is

[0091] So we can construct

[0092] Combining the above three items, the thrust coefficient of the fitted vector thruster can be expressed as:

[0093]

[0094] It can also be seen from the above function that the thrust coefficient of the vector thruster is affected by the coupling of multiple fluid parameters.

[0095] 2. Characterization of the hydrodynamic force and hydrodynamic torque on a vector-propelled AUV

[0096] The hydrodynamic force on the vector-propelled AUV includes the position force F during steady translational motion. POS , the damping force F for steady rotational motion DAM And the inertial force F during unsteady motion INE The corresponding hydrodynamic torque of the vector-propelled AUV also includes the position torque M POS , Damping torque M DAM and moment of inertia M INE Each force and moment can be described by dimensionless hydrodynamic coefficients, which are expressed as follows:

[0097] (1) Position force F on the vector-propelled AUV during steady translational motion POS and position torque M POS

[0098] The vector-propelled AUV is subject to the position force F POS and position torque M POS It is expressed as:

[0099]

[0100] Where ρ represents the fluid density, v represents the velocity amplitude of the vector-propelled AUV, S represents the maximum cross-sectional area of ​​the vector-propelled AUV, and L represents the length of the vector-propelled AUV. x0 is the drag factor of the vector-propelled AUV when both the angle of attack α and the sideslip angle β are 0, are the position derivatives, is the position derivative of the lift factor with respect to the angle of attack, is the position derivative of the side force factor with respect to the sideslip angle, is the position derivative of the yaw moment factor with respect to the sideslip angle, is the position derivative of the pitching moment factor with respect to the angle of attack.

[0101] (2) Damping force F on the steady rotational motion of the vector-propelled AUV DAM and damping torque M DAM

[0102] It can be written in component form as follows:

[0103]

[0104] In the formula, i = x, y, z, The value of the rotation angular velocity vector ω = 0 represents the increment of the hydrodynamic component or torque component corresponding to the unit angular velocity of the AUV, which is called the rotation derivative of force and torque. There are 18 of them in total. The dimensionless factors of the corresponding rotation derivatives are obtained by using the hydrodynamic definition and angular velocity, which are referred to as rotation derivatives for short. For the shape of a rotating body, when the rotation speed is not large, some rotation derivatives are very small and can be ignored. Therefore, the damping force F on the vector propulsion AUV is DAM and damping torque M DAM for:

[0105]

[0106] in, is the rotation derivative, is the lift factor to ω z The rotation derivative of is the lateral force factor to ω y The rotation derivative of is the rolling moment about ω x The rotation derivative of is the rolling moment about ωy The rotation derivative of is the yaw moment about ω x The rotation derivative of is the yaw moment about ω y The rotation derivative of is the pitch moment about ω z The rotation derivative of .

[0107] (3) Inertial force F on the unsteady motion of vector-propelled AUV INE and moment of inertia M INE

[0108] The inertial force represents the hydrodynamic force that the vector-propelled AUV is subjected to when performing unsteady motion. When the vector-propelled AUV performs unsteady motion, part of the work done by the external force is converted into the kinetic energy of the vector-propelled AUV, and another part is used to drive the fluid around the vector-propelled AUV to obtain kinetic energy, which is equivalent to the vector-propelled AUV adding a part of mass, called additional mass. The additional mass is only related to the shape of the vector-propelled AUV, and is described by a diagonal additional mass matrix λ. There are 21 independent additional masses, which can be simplified to the following form when the vector-propelled AUV has two symmetry planes:

[0109]

[0110] Applying the momentum theorem and the angular momentum theorem to the additional fluid, the inertial force F of the vector-propelled AUV in unsteady motion can be determined: INE and moment of inertia M INE It is expressed as:

[0111]

[0112] Among them are

[0113] Therefore, the above position force F POS , damping force F DAM and inertial force F INE The sum of the position torque M is the hydrodynamic force on the vector-propelled AUV. POS , Damping torque M DAM and moment of inertia M INE The sum is the hydrodynamic torque of the vector-propelled AUV. The hydrodynamic parameters of the vector-propelled AUV can be obtained through CFD simulation. The obtained hydrodynamic parameters include: the drag factor C of the vector-propelled AUV when the attack angle α and the sideslip angle β are both 0 x0 , and the position derivative And, the rotation derivative and the additional mass matrix

[0114] 3. The buoyancy force F exerted on the vector-propelled AUV ΔB and the buoyancy moment M ΔB Characterization

[0115] The vector-propelled AUV will be affected by the buoyancy of gravity underwater. The gravity on the vector-propelled AUV is G=mg and acts on the center of gravity, with a vertical downward direction, and g is the acceleration of gravity. The buoyancy on the vector-propelled AUV is B=ρgV and acts on the center of buoyancy, with a vertical upward direction, ρ represents the fluid density, and V represents the volume of the vector-propelled AUV.

[0116] The net buoyancy of the vector-propelled AUV is ΔB=BG. The net buoyancy ΔB=BG converted to the body coordinate system is the heavy buoyancy F of the vector-propelled AUV. ΔB for:

[0117]

[0118] The buoyancy moment M in the body coordinate system of the vector-propelled AUV is ΔB for:

[0119]

[0120] in is the radius r from the center of gravity to the center of buoyancy of the vector-propelled AUV cg The components of the three directions in the body coordinate system (x cg ,y cg , z cg ) is an antisymmetric matrix, and there is

[0121] In summary, the sum of the thrust, hydrodynamic force and buoyancy force constructed above is taken as the vector F of all external forces on the vector propulsion AUV in the body coordinate system, and the sum of the thrust torque, hydrodynamic torque and buoyancy torque constructed above is taken as the vector M of all external torques on the vector propulsion AUV in the body coordinate system. Then, the expressions of the above forces and torques are substituted into the six-degree-of-freedom dynamic equation: It can be sorted out into:

[0122]

[0123] in,

[0124]

[0125] Based on the fact that the mass of the AUV remains unchanged during navigation, it can be determined Since the constructed position force and damping force already include the characteristics of ideal fluid force and viscous fluid force, the six-degree-of-freedom dynamic equation can be simplified as follows:

[0126]

[0127] in,

[0128] The six-degree-of-freedom dynamic equations and kinematic equations of the vector-propelled AUV constructed in this application are used to control the motion of the vector-propelled AUV. Since the coupling characteristics of the vector propulsion are considered when constructing the six-degree-of-freedom dynamic equations, the accuracy of the motion control can be improved and the control performance can be optimized.

[0129] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A dynamic modeling method for a vector-propelled AUV, characterized in that: The kinetic modeling method comprises: The hydrodynamic parameters of the vector-propelled AUV are obtained through CFD simulation method; The vector propulsion performance of the vector thruster in the vector propulsion AUV under different operating conditions and under the action of different fluid parameters is obtained by CFD simulation method. The vector propulsion performance includes thruster thrust and thruster torque. According to the vector propulsion performance of the vector thruster under different operating conditions and under the action of different fluid parameters, the thrust coefficient K of the vector thruster is obtained by fitting. p Relationship with fluid parameters; Hydrodynamic parameters of vector-propelled AUV and thrust coefficient K of vector thruster p , the six-degree-of-freedom dynamic equations related to the working parameters of the vector thruster and the fluid parameters are constructed Where P = m(v + ω × r c ) is the momentum of the vector-propelled AUV, L = Iω + r c ×mv is the momentum of the vector-propelled AUV, m is the mass of the vector-propelled AUV, v is the velocity vector of the center of buoyancy of the vector-propelled AUV in the ground coordinate system, ω is the rotational angular velocity vector of the vector-propelled AUV in the ground coordinate system, r c is the vector radius from the center of mass of the vector-propelled AUV to the center of buoyancy, I represents the inertia tensor matrix of the vector-propelled AUV about the center of buoyancy; F represents the vector of all external forces on the vector-propelled AUV in the body coordinate system, M represents the vector of all external torques on the vector-propelled AUV in the body coordinate system; all external forces on the vector-propelled AUV include hydrodynamic force, buoyancy force and thruster thrust, all external torques on the vector-propelled AUV include hydrodynamic torque, buoyancy torque and thruster thrust, vector propulsion performance and thrust coefficient K p Related to the operating parameters of the vector thruster; A dynamic model of the vector-propelled AUV is established by using the six-degree-of-freedom dynamic equation in combination with the kinematic equation of the vector-propelled AUV, and the dynamic model of the vector-propelled AUV is used to perform motion simulation on the vector-propelled AUV; Among them, the body coordinate system Oxyz takes the buoyancy center of the vector-propelled AUV as the coordinate origin O, the navigation direction of the vector-propelled AUV is the positive x direction, the direction pointing to the port side of the vector-propelled AUV is the positive y direction, and the positive z direction is perpendicular to the xy plane and upward.

2. The kinetic modeling method according to claim 1, characterized in that: The vector propulsion performance of the vector thruster under different operating conditions and under different fluid parameters includes: Get the vector thruster in open water at different vector deflection angles δ e Below, different vector deflection angles δ r Under different speed coefficients and different vector deflection angles δ e With δ r Vector propulsion performance in coupled state; And, obtain the vector thruster in the independent maneuvering state at different lateral and longitudinal flow angles α obl Under different vector deflection angles δ e Below, different vector deflection angles δ r Under different speed coefficients and different vector deflection angles δ e With δ r Vector propulsion performance in coupled state; And, obtain the vector propulsion AUV formed by the vector thruster after being assembled on the AUV body and performing maneuvering under the conditions of straight navigation and oblique flow at different vector deflection angles δ e Below, different vector deflection angles δ r Under different speed coefficients and different vector deflection angles δ e With δ r Vector propulsion performance in coupled state.

3. The kinetic modeling method according to claim 2, characterized in that: The thrust coefficient K of the vector thruster is obtained by fitting p The relationships with fluid parameters include: The thrust coefficient of the vector thruster is obtained by fitting K pJ is the fitted function related to the speed coefficient J, Based on the fitting and vector deflection angle δ e With δ r The related interpolation surface f δ Sure, Based on the fitting results, the deflection angle δ and the oblique flow angle α obl The related interpolation surface f obl Sure.

4. The kinetic modeling method according to claim 3, characterized in that: K pJ =A J J w +B J Among them, J w is the corrected advance coefficient after considering the influence of the AUV body on the wake field of the vector thruster, and J w =J(1-w), J is the advance coefficient, w is the wake fraction; A J and Β J are the parameter matrices obtained by fitting.

5. The kinetic modeling method according to claim 3, characterized in that: Among them, f δ (δ e ,δ r ) represents the interpolation surface f obtained by fitting δ The deflection angle δ of the vector e With δ r The corresponding value; f obl (α obly ,δ e ) represents the interpolation surface f obtained by fitting obl The deflection angle δ and the oblique flow angle component α obly The corresponding value, f obl (α oblz ,δ r ) represents the interpolation surface f obtained by fitting obl The deflection angle δ and the oblique flow angle component α oblz The corresponding value; Oblique flow angle component is the oblique flow angle α obl The y-direction component in the body coordinate system, the oblique flow angle component is the oblique flow angle α obl The components of the velocity vector v at the center of buoyancy of the vector-propelled AUV in the three directions of the body coordinate system are (v x ,v y ,v z ), the component of the rotational angular velocity vector ω of the vector-propelled AUV in the y direction of the body coordinate system is ω y , the component in the z direction of the body coordinate system is ω z , L AC It is the distance from the center of the vector thruster in the vector propulsion AUV to the center of buoyancy of the vector propulsion AUV.

6. The kinetic modeling method according to claim 1, characterized in that: The thrust force of the thruster on the vector-propelled AUV Thruster thrust torque on vector-propelled AUV Among them, the thrust coefficient of the vector thruster obtained by fitting is Among them, K Tpx , K Tpy , K Tpz They are thrust coefficient K p The force component coefficients in the three directions of the body coordinate system, K Qpx , K Qpy , K Qpz They are thrust coefficient K p The torque component coefficients in the three directions of the body coordinate system; ρ represents the fluid density, n is the speed of the vector thruster, D is the diameter of the vector thruster, L AC It is the distance from the center of the vector thruster in the vector propulsion AUV to the center of buoyancy of the vector propulsion AUV.

7. The kinetic modeling method according to claim 1, characterized in that: The hydrodynamic parameters of the vector-propelled AUV obtained by CFD simulation method include: The drag factor C of a vector-propelled AUV when both the attack angle α and the sideslip angle β are 0 x0 ; and the position derivative of the lift factor with respect to the angle of attack Position derivative of the side force factor with respect to the sideslip angle Position derivative of the yaw moment factor with respect to the sideslip angle Position derivative of the pitching moment factor with respect to the angle of attack And, the lift factor is z The rotational derivative of Lateral force factor vs. ω y The rotation derivative of Rolling moment on ω x The rotational derivative of Rolling moment on ω y The rotational derivative of Yaw moment on ω x The rotational derivative of Yaw moment on ω y The rotational derivative of Pitch moment about ω z The rotational derivative of And, the additional mass matrix 8. The kinetic modeling method according to claim 7, characterized in that: The hydrodynamic forces on a vector-propelled AUV include position forces Damping force and inertial force F INE ; The hydrodynamic torque on the vector-propelled AUV includes the position torque Damping torque and moment of inertia M INE ; in, v is the velocity vector at the center of buoyancy of the vector-propelled AUV and its components in the three directions of the body coordinate system are (v x ,v y ,v z ), ω is the rotational angular velocity vector of the vector-propelled AUV and its components in the three directions of the body coordinate system are (ω x ,ω y ,ω z ), ρ represents the fluid density, v represents the velocity amplitude of the vector-propelled AUV, S represents the maximum cross-sectional area of ​​the vector-propelled AUV, and L represents the length of the vector-propelled AUV.

9. The kinetic modeling method according to claim 1, characterized in that: The buoyancy force of the vector-propelled AUV The buoyancy moment in the body coordinate system of the vector-propelled AUV G is the gravity on the vector-propelled AUV and G=mg, B is the buoyancy on the vector-propelled AUV and B=ρgV, m is the mass of the vector-propelled AUV, g is the gravitational acceleration, ρ represents the fluid density, and V represents the volume of the vector-propelled AUV; is the component of the vector radius rcg from the center of gravity to the center of buoyancy of the vector-propelled AUV in the three directions of the body coordinate system (x cg ,y cg , z cg ) is an antisymmetric matrix, and there is is the coordinate transformation matrix from the ground coordinate system to the body coordinate system. The ground coordinate system O e x e y e z e Connected to the ground.

10. The kinetic modeling method according to claim 1, characterized in that: The kinetic modeling method also includes: The kinematic equations of the vector-propelled AUV are constructed as follows: Among them, the position coordinates of the center of buoyancy of the vector-propelled AUV in the ground coordinate system are (x e ,y e ,z e ), the components of the velocity vector v at the center of buoyancy of the vector-propelled AUV in the three directions of the body coordinate system are (v x ,v y ,v z ); The components of the rotational angular velocity vector ω of the vector-propelled AUV in the three directions of the body coordinate system are (ω x ,ω y ,ω z );θ is the pitch angle of the vector-propelled AUV relative to the ground coordinate system, ψ is the yaw angle of the vector-propelled AUV relative to the ground coordinate system, φ is the roll angle of the vector-propelled AUV relative to the ground coordinate system; the ground coordinate system O e x e y e z e Connected to the ground.

Images