AUV horizontal plane control method based on full-revolution propeller

Abstract

The application discloses an AUV horizontal plane control method based on a full-revolution propeller, and the method comprises the following steps: establishing a thrust model of the full-revolution propeller; establishing a thrust distribution matrix of the full-revolution propeller; based on the thrust model of the full-revolution propeller and in combination with the thrust distribution matrix of the full-revolution propeller, a thrust distribution algorithm of the full-revolution propeller is established; according to the self-disturbance resisting principle and in combination with the thrust distribution algorithm of the full-revolution propeller, an AUV horizontal plane control model is constructed; and based on the AUV horizontal plane control model, the control force and the moment of the full-revolution propeller in the corresponding direction are calculated according to the deviation between the current heading of the AUV and the command heading, so that the AUV horizontal plane control is realized; the AUV low-speed horizontal plane control is realized based on the full-revolution propeller, and the problem of insufficient AUV control performance in the working condition of narrow environment and low-speed navigation is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of AUV navigation control, in particular to an AUV horizontal plane control method based on a full-revolution thruster. BACKGROUND

[0002] As an important tool for human to explore and develop the ocean, the autonomous underwater vehicle (AUV) has a great development prospect in military and civilian fields.

[0003] The maneuverability of underwater vehicles is an important indicator. With the increasing diversity of AUV tasks and the complexity of the environment, the control accuracy of underwater navigation of AUVs is becoming more and more urgent. When performing tasks, if the initial state is at a low speed, the steering ability of the rudder surface will be greatly reduced, and it is difficult to achieve horizontal plane control of the AUV. When there is water flow velocity interference, it is difficult to maintain the same heading, and since a large turning radius is required under low-speed navigation conditions to change the heading.

[0004] Therefore, how to realize the low-speed horizontal plane control of the AUV is a problem that those skilled in the art need to solve. SUMMARY

[0005] Therefore, the present application provides an AUV horizontal plane control method based on a full-revolution thruster, which realizes low-speed horizontal plane control of the AUV based on the full-revolution thruster, and effectively solves the problem of insufficient control performance of the AUV in narrow environments and low-speed navigation conditions.

[0006] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0007] The present application provides an AUV horizontal plane control method based on a full-revolution thruster, comprising the following steps:

[0008] S1, establishing a thrust model of the full-revolution thruster;

[0009] S2, establishing a thrust distribution matrix of the full-revolution thruster, based on the thrust model of the full-revolution thruster, and combining the thrust distribution matrix of the full-revolution thruster, a thrust distribution algorithm of the full-revolution thruster is established;

[0010] S3, according to the self-disturbance principle and the thrust distribution algorithm of the full-revolution thruster, an AUV horizontal plane control model is constructed;

[0011] S4, based on the AUV horizontal plane control model, the control force and torque of the full-revolution thruster in the corresponding direction are calculated according to the deviation between the current heading of the AUV and the command heading, and the horizontal plane control of the AUV is realized.

[0012] Further, the full-revolution thruster arrangement is installed at the bow and the stern of the AUV body.

[0013] Further, in the step S1, the thrust model of the full-revolution thruster is:

[0014]

[0015] wherein ρ is the density of water, n is the rotating speed of the propeller, D p is the diameter of the propeller, k T , k TN respectively represent the thrust coefficient of the propeller and the duct.

[0016] Further, in the step S2, the thrust distribution matrix of the full-revolution thruster is:

[0017]

[0018] wherein F X represents the control force acting on the AUV in the axial direction, positive for the forward direction, F y represents the control force acting on the AUV in the lateral direction, positive for the right direction, M represents the control moment acting on the AUV, positive for the counterclockwise direction, α1 represents the azimuth angle of the full-revolution thruster 1, α2 represents the azimuth angle of the full-revolution thruster 2, L1 represents the force arm of the full-revolution thruster 1, L2 represents the force arm of the full-revolution thruster 2, T1 represents the thrust size of the full-revolution thruster 1, and T2 represents the thrust size of the full-revolution thruster 2.

[0019] The formula (2) is converted into formula (3) as shown:

[0020] τ=B(α)T (3)

[0021] wherein τ=[F x F y M] T is the control force and control moment matrix,

[0022] is the thrust distribution gain matrix, and T=[T1 T2] is the thrust size matrix of the two thrusters.

[0023] And the optimization objectives are the optimal energy consumption, the minimum thrust error, the minimum change of the azimuth angle and the minimum change of the thrust, the constraints of the azimuth angle and the thrust, and the constraints of the change of the azimuth angle and the thrust, a thrust distribution algorithm is established, wherein the thrust distribution objective function and the constraint conditions are respectively:

[0024] The thrust distribution objective function is:

[0025] J=T TW1T + s T W2s + (a - a0) T W3(a - a0) + (T - T0) T W4(T - T0) (4)

[0026] The constraint condition is:

[0027]

[0028] In the formula, T represents the thrust, the upper index T represents the transpose, a is the rotation angle of the propeller, T0 is the thrust at the last time, a0 is the rotation angle at the last time; T min and T max are the minimum and maximum thrusts that the propeller can generate, AT min and AT max are the minimum and maximum thrust change rates that the propeller can generate; a min and a max are the minimum and maximum rotation angles of the propeller, Da min and Da max are the minimum and maximum rotation angle change rates of the propeller; s is the relaxation variable of the thrust, W1, W2, W3 and W4 are diagonal weight matrices.

[0029] Further, the AUV horizontal plane control model comprises an extended state observer model.

[0030] The extended state observer model is specifically constructed as follows.

[0031] A kinematic model of the AUV horizontal plane is established as follows:

[0032]

[0033] In the formula, x, y and y are respectively the longitudinal displacement, lateral displacement and heading angle of the AUV in the geodetic coordinate system, u, v and r are respectively the longitudinal velocity, lateral velocity and heading angle velocity of the AUV body coordinate system.

[0034] The state transition matrix is represented by a matrix R:

[0035]

[0036] On the basis of the AUV maneuvering control equation, an AUV horizontal plane dynamics equation is established as follows:

[0037]

[0038] In the formula, v = [u, v, r] T is a velocity vector, h = [x, y, y] T is a position and attitude vector, and t = [t x , ty ,τ ψ ] T is the control force and moment in three degrees of freedom in horizontal plane, d = [d x ,d y ,d ψ ] T is the disturbance in three degrees of freedom in horizontal plane, D is the fluid viscous hydrodynamic derivative matrix, where X u is the axial hydrodynamic derivative related to velocity u, Y v is the lateral hydrodynamic derivative related to lateral velocity v, Y r is the lateral hydrodynamic derivative related to yaw rate r, N v is the yawing moment hydrodynamic derivative related to lateral velocity v, N r is the yawing moment hydrodynamic derivative related to yaw rate r; M RB is the system inertia matrix, m is the mass of AUV, x G is the x-coordinate of the center of mass in the body coordinate system of AUV, y G is the y-coordinate of the center of mass in the body coordinate system of AUV, I z is the moment of inertia of AUV about z-axis; M A is the fluid inertia hydrodynamic derivative matrix, where is the axial hydrodynamic derivative related to acceleration , is the lateral hydrodynamic derivative related to lateral acceleration , is the lateral hydrodynamic derivative related to yaw rate acceleration , is the yawing moment hydrodynamic derivative related to lateral acceleration , r is the yawing moment hydrodynamic derivative related to yaw rate acceleration r; C RB is the Coriolis matrix, z G is the z-coordinate of the center of mass in the body coordinate system of AUV; R is the transformation matrix;

[0039] The AUV horizontal plane dynamics equation (8) is converted into as shown in equation (9):

[0040]

[0041] In the formula: M = M RB + M A , C = C RB (υ) + D, f (t) = -M -1 d;

[0042] The AUV state variable is defined as x h1 = η, x h2 = υ, xh3 = f(t), equation (9) is described in state space form as:

[0043]

[0044] The extended state observer is constructed according to the extended state space as:

[0045]

[0046] In the formula: l h1 ,l h2 ,l h3 is the observer gain matrix:

[0047] The dynamic equation of the extended state observer is established by combining equation (10) and equation (11) as:

[0048]

[0049] In the formula: is the observation error of the state variable x h1 .

[0050] Further, the AUV horizontal plane control model also includes: a three-channel coupled PD controller model;

[0051] The construction of the three-channel coupled PD controller model specifically includes:

[0052] The horizontal plane dynamics equation (9) is converted to:

[0053]

[0054] The control rate of the horizontal plane is established according to the observation result of the observer as:

[0055]

[0056] Substituting it into the horizontal plane dynamics equation (9), three single-input single-output series integral type systems are constructed:

[0057]

[0058] In the formula: τ 10 is the control rate of the decoupling system, and the PD controller model is constructed as:

[0059]

[0060] In the formula: η 1d represents the horizontal plane longitudinal displacement, lateral displacement and heading angle command, represents the horizontal plane longitudinal velocity, lateral velocity and heading angle velocity command, represents the longitudinal acceleration, lateral acceleration and heading angle acceleration command in the horizontal plane, k 1p represents the PD controller gain matrix related to the longitudinal displacement, lateral displacement and heading angle in the horizontal plane, k 1d represents the PD controller gain matrix related to the longitudinal velocity, lateral velocity and heading angle velocity.

[0061] Compared with the prior art, the present application has the following beneficial effects:

[0062] 1、The present application considers that the AUV is difficult to realize the low-speed horizontal plane control due to the insufficient control performance in the low-speed working condition and narrow environment, and proposes an AUV horizontal plane control method based on the full-reversing propeller, so that the low-speed horizontal plane control of the AUV can be realized, and the problem that the AUV is difficult to realize the heading change and keeping due to the low rudder effect at low speed is effectively solved. BRIEF DESCRIPTION OF DRAWINGS

[0063] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0064] The drawings are used to provide a further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with the embodiments of the present application, and do not constitute a limitation on the present application.

[0065] Figure 1 The arrangement schematic diagram of the full-reversing propeller provided by the embodiments of the present application.

[0066] Figure 2 The flowchart of the AUV horizontal plane control method based on the full-reversing propeller provided by the embodiments of the present application.

[0067] Figure 3 The low-speed horizontal plane control principle diagram of the AUV provided by the embodiments of the present application.

[0068] Figure 4 The four-quadrant working condition schematic diagram of the propeller provided by the embodiments of the present application.

[0069] Figure 5 The heading change curve diagram of the horizontal plane control AUV provided by the embodiments of the present application.

[0070] Figure 6 The track curve diagram of the horizontal plane control AUV provided by the embodiments of the present application.

[0071] Figure 7The horizontal plane control AUV track deviation curve is provided for the embodiment of the present application. DETAILED DESCRIPTION

[0072] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0073] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0074] In the description of the present application, it should be noted that the terms "upper", "lower", "left", "right", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, various serial numbers are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0075] The present application takes the "SUBOFF" type AUV as the research object, in order to improve its maneuvering performance, according to its geometric characteristics, such as Figure 1 As shown in the figure, one propeller capable of 360-degree rotation is arranged at the bow and stern of the AUV. The yaw moment is generated by the rotation speed and thrust direction, so as to perform the heading control. Under this configuration, the control moment required for the heading control is generated by the propeller thrust.

[0076] Referring to Figure 2 As shown in the figure, the embodiment of the present application provides an AUV horizontal plane control method based on a full-rotation propeller, and the principle of the AUV horizontal plane control based on the full-rotation propeller is as shown in Figure 3 The method specifically comprises the following steps:

[0077] S1: establishing a thrust model of the full-rotation propeller;

[0078] The thrust model of the full-rotation propeller is established, the model and parameters of the propeller are determined, the hydrodynamic performance of the propeller is analyzed by a numerical simulation method, the open water performance curve of the propeller is obtained, and the size of the thrust coefficient is obtained. The thrust of the propeller at different navigation speeds is obtained by inputting the thrust formula. The force and torque generated by the propeller are applied to the AUV body. The full-rotation propeller is installed at the bow and stern of the AUV and can rotate in the horizontal plane. The single propeller model is established according to the above, and the propeller thrust closed loop is established. The desired thrust is input, and the propeller control propeller speed reaches the command thrust. When the propeller generates a thrust T, the thrust direction and the AUV axis are at an angle δ, the rotation torque is TsinδL, and the side force is Tsinδ, where L is the axial distance between the propeller position and the center of gravity.

[0079] The thrust model construction method of the full-rotation propeller is specifically:

[0080] According to the different directions of the AUV longitudinal velocity (relative to the water) and the propeller speed, the working conditions of the propeller are divided into four quadrants as shown in the accompanying Figure 4 .

[0081] The thrust model of the propeller is:

[0082] In the formula, ρ is the density of water; n is the propeller speed, D p is the propeller diameter, k T , k TN respectively represent the thrust coefficients of the propeller and the duct.

[0083] For the thrust coefficient in formula (1), the thrust coefficient curve of the propeller under different working conditions is obtained by using the numerical simulation method based on computational fluid dynamics.

[0084] S2: Establishing a thrust distribution matrix of the full-rotation propeller, based on the thrust model of the full-rotation propeller, and combining the thrust distribution matrix of the full-rotation propeller, a thrust distribution algorithm of the full-rotation propeller is established;

[0085] The thrust distribution is mainly divided into two categories from the structure: the first category is the objective function, which includes the objective function of the propeller energy consumption, distribution error, propeller angle change rate, singular configuration and other optimization items. The second category is the constraint condition, including the equality constraint condition meeting the controller output instruction and the inequality constraint condition meeting the mechanical condition limit of the propeller. The addition of the equality constraint condition restricts the thrust output by the propelling system, and ensures that the thrust output by the propelling system meets the instruction of the controller, so as to realize the dynamic positioning function. The addition of the inequality constraint condition is for the need to limit the thrust change rate and the propeller angle rotation change rate, which is specifically:

[0086] The thrust allocation matrix expression is shown as equation (2):

[0087]

[0088] Wherein, F X represents the control force acting on the AUV in the axial direction, positive for pointing forward, F y represents the control force acting on the AUV in the lateral direction, positive for pointing right, M represents the control moment acting on the AUV, positive for counterclockwise direction, α1 represents the azimuth angle of the azimuth thruster 1, α2 represents the azimuth angle of the azimuth thruster 2, L1 represents the force arm of the azimuth thruster 1, L2 represents the force arm of the azimuth thruster 2, T1 represents the thrust size of the azimuth thruster 1, and T2 represents the thrust size of the azimuth thruster 2.

[0089] The above equation can be written as shown in equation (3):

[0090] τ=B(α)T (3)

[0091] In the equation, τ=[F x F y M] T is the control force and control moment matrix, is the thrust allocation gain matrix, and T=[T1 T2] is the thrust size matrix of the two thrusters.

[0092] With the optimization objectives of optimal energy consumption, minimum thrust error, minimum change in azimuth angle and minimum change in thrust, considering the constraints of the azimuth angle and the thrust and the constraints of the change rate of the azimuth angle and the thrust, a thrust allocation algorithm is established, wherein the thrust allocation objective function and the constraint conditions are shown as equations (4) and (5) respectively:

[0093] J=T T W1T+s T W2s+(α-α0) T W3(α-α0)+(T-T0) T W4(T-T0) (4)

[0094]

[0095] In the equation: T represents the thrust, the upper index T represents the transpose, α is the azimuth angle of the azimuth thruster, T0 is the thrust at the previous moment, and α0 is the azimuth angle at the previous moment; T min and T max are the minimum and maximum thrusts that can be generated by the azimuth thruster, ΔT min and ΔT max are the minimum and maximum change rates of the thrust that can be generated by the azimuth thruster; α min and α maxThe minimum and maximum turning angles of the full-rotation propeller, Δα min And Δα max The minimum and maximum turning angle rates of the full-rotation propeller; s is a relaxation variable of the thrust, W1, W2, W3 and W4 are diagonal weight matrices.

[0096] In the embodiment of the application, a sequence quadratic programming algorithm (SQP) is used to optimize a thrust distribution target function, so as to achieve the purpose of optimal thrust distribution.

[0097] S3: An AUV horizontal plane controller (i.e., an AUV horizontal plane control model) is established, and horizontal plane control of the AUV is realized based on active disturbance rejection control, specifically as follows:

[0098] In the horizontal plane, the kinematic model of the AUV horizontal plane is simplified as shown in formula (6).

[0099]

[0100] In the formula, x, y and ψ are respectively the longitudinal displacement, lateral displacement and heading angle of the AUV in the geodetic coordinate system, and u, v and r are respectively the longitudinal velocity, lateral velocity and heading angular velocity of the AUV in the body coordinate system.

[0101] The transition matrix is represented by a matrix R as shown in formula (7).

[0102]

[0103] Based on the AUV maneuvering control equation, the horizontal plane dynamics equation is simplified as shown in formula (8):

[0104]

[0105] In the formula, υ=[u,v,r] T is a velocity vector, η=[x,y,ψ] T is a position and attitude vector, τ=[τ x ,τ y ,τ ψ ] T is a three-degree-of-freedom control force and moment, d=[d x ,d y ,d ψ ] T is a three-degree-of-freedom disturbance in the horizontal plane (including sea wave disturbance and sea current disturbance), and the remaining items are hydrodynamic parameters.

[0106] According to the active disturbance rejection principle, the AUV horizontal plane controller is constructed, and the construction of the controller includes construction of an extended state observer and construction of a three-channel coupled PD controller.

[0107] First, the extended state observer is constructed:

[0108] The AUV horizontal plane dynamics equation is converted to equation (9).

[0109]

[0110] In the formula: M = M RB + M A , C = C RB (v) + D, f (t) = -M -1 d.

[0111] The AUV state variable is defined as x h1 = η, x h2 = v, x h3 = f (t), equation (9) is described in state space form (10) as follows:

[0112]

[0113] According to the extended state space, the extended state observer is constructed as shown in equation (11):

[0114]

[0115] In the formula: l h1 , l h2 , l h3 is the observer gain matrix.

[0116] The dynamic equation of the extended state observer is obtained by combining equation (10) and equation (11) as shown in equation (12):

[0117]

[0118] In the formula: is the observation error of state variable x h1 .

[0119] In order to ensure the stability of the observer and simplify the parameter adjustment process, all poles of the longitudinal, lateral and heading three-channel observers are set at -ω ox , -ω oy and -ω oψ , and the observer gain matrix is:

[0120]

[0121] Then a three-channel coupled PD controller is constructed:

[0122] The dynamics equation (9) is converted to the form as shown in equation (13):

[0123]

[0124] The control rate of the horizontal plane is constructed according to the observation results of the observer as shown in formula (14).

[0125]

[0126] Substitute it into the horizontal plane dynamic equation (9), if the state observation value and If the original three-channel coupled nonlinear system is accurate, it can be transformed into three series-connected integral systems with single input and single output as shown in Equation (15):

[0127]

[0128] Where: τ 10 To decouple the control rate of the system, a PD controller is constructed as shown in formula (16):

[0129]

[0130] Where: η 1d Indicates the horizontal plane longitudinal, lateral displacement and heading angle instructions, Indicates the horizontal plane longitudinal velocity, lateral velocity and heading angular velocity instructions, Indicates the horizontal plane longitudinal acceleration, lateral acceleration and heading angular acceleration instructions. For the power control task, the speed and acceleration instructions are both set to 0; k 1p ,k 1d is the PD controller gain matrix. In order to ensure the stability of the controller and simplify the parameter adjustment process, the pole configuration method is used to configure the poles of the longitudinal, lateral and heading channels at -ω respectively. cx 、-ω cy and -ω cψ , then the gain matrix is:

[0131]

[0132] S4: Based on the AUV horizontal plane control model, according to the deviation between the AUV's current heading and the command heading, the control force and torque of the azimuth thruster in the corresponding direction are calculated to achieve the AUV horizontal plane control. Specifically:

[0133] like Figure 3 As shown in the figure, the control force and torque in the corresponding direction are calculated according to the deviation between the current heading of the AUV and the command heading; the thrust distribution module converts the control force and torque output by the controller into the rotation speed, turning angle and rudder angle instructions of the azimuth thruster and rudder. The force and torque generated by the actuator act on the AUV, thereby completing the closed-loop motion control of the AUV at low and micro speeds.

[0134] The following is the AUV horizontal plane low speed horizontal plane control test verification:

[0135] In the AUV speed 1.5Kn, given the initial heading 45°, the initial depth 30m, there is a vertical direction 1Kn ocean current interference, the simulation of the horizontal plane orientation control based on the full rotation propeller, the simulation results are shown in the following figures Figure 5 -AUV heading curve, attached Figure 6 -AUV horizontal plane trajectory curve and attached Figure 7 -AUV horizontal plane trajectory deviation curve. As can be seen from the figure, under the influence of ocean current, by increasing the full rotation propeller for AUV horizontal plane control, the control accuracy of AUV can be effectively improved, the AUV heading retention is high, and the trajectory deviation is small.

[0136] Through the above embodiment description, those skilled in the art can know that the present application provides an AUV horizontal plane control method based on full rotation propeller. A pair of full rotation auxiliary propellers are arranged at the bow and stern of the AUV. By constructing the thrust model, thrust distribution model and AUV horizontal plane control model of the full rotation propeller, the low speed horizontal plane control of the AUV is realized, the problem of insufficient AUV control performance in narrow environment and low speed navigation working condition is effectively solved, and the control accuracy and robustness of low speed navigation control are improved.

[0137] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A horizontal plane control method for an AUV based on an azimuth thruster, characterized in that: The following steps are involved: S1. Establish a thrust model for the azimuth thruster; S2. Establishing a thrust distribution matrix for the azimuth propeller, and establishing a thrust distribution algorithm for the azimuth propeller based on the thrust model of the azimuth propeller and in combination with the thrust distribution matrix of the azimuth propeller; S3. Constructing an AUV horizontal plane control model based on the active disturbance rejection principle and the thrust distribution algorithm of the azimuth thruster; the AUV horizontal plane control model includes: a three-channel coupled PD controller model; The construction of the three-channel coupled PD controller model specifically includes: The horizontal plane dynamic equation is transformed into: Where η is the position and attitude vector, R represents the transformation matrix, τ is the control force and torque of the three degrees of freedom, M = M RB +M A ,C=C RB (υ)+D,f(t)=-M -1 d, where M RB is the system inertia matrix, M A is the fluid inertial hydrodynamic derivative matrix, C RB is the Coriolis matrix, v is the velocity vector, D is the fluid viscous hydrodynamic derivative matrix, and d is the disturbance of the three degrees of freedom in the horizontal plane; According to the observation results of the observer, the control force and control torque of the horizontal plane are established as follows: Substituting it into the horizontal plane dynamics equation, we construct three series integral systems with single input and single output: Where: τ 10 is the control rate of the decoupled system, x h2 and x h3 is the state variable; the PD controller model is constructed as: Where: η 1d Indicates the horizontal plane longitudinal, lateral displacement and heading angle instructions, Indicates the horizontal plane longitudinal velocity, lateral velocity and heading angular velocity instructions, Indicates the horizontal plane longitudinal acceleration, lateral acceleration and heading angular acceleration instructions, k 1p is the PD controller gain matrix related to the horizontal longitudinal displacement, lateral displacement and heading angle, k 1d is the PD controller gain matrix related to the horizontal plane longitudinal velocity, lateral velocity and heading angular velocity; S4. Based on the AUV horizontal plane control model, according to the deviation between the AUV's current heading and the command heading, the control force and torque of the azimuth thruster in the corresponding direction are calculated to achieve AUV horizontal plane control.

2. The AUV horizontal plane control method based on an azimuth thruster according to claim 1 is characterized in that: The azimuth thrusters are arranged and installed at the bow and stern of the AUV body.

3. The AUV horizontal plane control method based on an azimuth thruster according to claim 1, characterized in that: In step S1, the thrust model of the azimuth thruster is: Where ρ is the density of water; n is the propeller speed, D p is the propeller diameter, k T 、k TN Represent the thrust coefficients of propeller and duct respectively.

4. The AUV horizontal plane control method based on an azimuth thruster according to claim 3 is characterized in that: In step S2, the thrust distribution matrix of the azimuth thruster is: Among them, F X Indicates the control force acting on the AUV axis, pointing forward is positive, F y represents the lateral control force acting on the AUV, pointing to the right is positive, M represents the control torque acting on the AUV, counterclockwise is positive, α1 represents the azimuth angle of azimuth thruster 1, α2 represents the azimuth angle of azimuth thruster 2, L1 represents the moment arm of azimuth thruster 1, L2 represents the moment arm of azimuth thruster 2, T1 represents the thrust of azimuth thruster 1, and T2 represents the thrust of azimuth thruster 2; Convert equation (2) into equation (3): τ=B(α)T (3) Where, τ=[F x F y M] T is the control force and control torque matrix, is the thrust distribution gain matrix, T = [T1 T2] is the thrust size matrix of the two thrusters; Taking optimal energy consumption, minimum thrust error, minimum rotation angle change, and minimum thrust change as optimization goals, and considering the rotation angle and thrust constraints as well as the rotation angle and thrust change rate constraints, a thrust allocation algorithm is established. The thrust allocation algorithm includes a thrust allocation objective function and constraints, where: The thrust distribution objective function is: J=T T W1T+s T W2s+(α-α0) T W3(α-α0)+(T-T0) T W4(T-T0) (4) The constraints are: Where: T represents thrust, superscript T represents transposition, α is the rotation angle of the azimuth thruster, T0 is the thrust at the previous moment, α0 is the rotation angle at the previous moment; T min With T max are the minimum and maximum thrusts that the azimuth thruster can generate, ΔT min and ΔT max is the minimum and maximum thrust change rate that the azimuth thruster can produce; α min With α max are the minimum and maximum rotation angles of the azimuth thruster, Δα min With Δα max are the minimum and maximum rotation angle change rates of the azimuth thruster; s is the slack variable of the thrust, and W1, W2, W3, and W4 are the diagonal weight matrices.

5. The AUV horizontal plane control method based on an azimuth thruster according to claim 4 is characterized in that: In step S3, the AUV horizontal plane control model includes: an extended state observer model; The construction of the extended state observer model specifically includes: Establish the kinematic model of the AUV horizontal plane: Where: x, y, ψ are the longitudinal displacement, lateral displacement and heading angle of the AUV in the geodetic coordinate system, u, v, r are the longitudinal velocity, lateral velocity and heading angular velocity of the AUV in the body coordinate system, respectively. Use matrix R to represent the transition matrix: Establish the AUV horizontal surface dynamics equation: Where: υ=[u,v,r] T is the velocity vector, η=[x,y,ψ] T is the position and attitude vector, τ=[τ x ,τ y ,τ ψ ] T is the control force and torque of three degrees of freedom, d=[d x ,d y ,d ψ ] T is the disturbance of the three degrees of freedom on the horizontal plane, D is the fluid viscous hydrodynamic derivative matrix, X u is the axial hydrodynamic derivative related to the velocity u, Y v is the lateral hydrodynamic derivative related to the lateral velocity v, Y r is the lateral hydrodynamic derivative related to the steering angular velocity r, N v is the hydrodynamic derivative of the bow moment related to the lateral velocity v, N r is the hydrodynamic derivative of the bow moment related to the steering angular velocity r; M RB is the system inertia matrix, m is the mass of AUV, x G is the x-coordinate of the center of gravity in the AUV body coordinate system, y G is the y-direction coordinate of the center of gravity in the AUV body coordinate system, I z is the moment of inertia of AUV around the z axis; M A is the fluid inertial hydrodynamic derivative matrix, where With acceleration The associated axial hydrodynamic derivative, is the lateral acceleration The associated lateral hydrodynamic derivative, is the steering angular acceleration The associated lateral hydrodynamic derivative, is the lateral acceleration Related hydrodynamic derivative of bow moment, N r is the hydrodynamic derivative of the bow moment related to the steering angular acceleration r; C RB is the Coriolis matrix, z G is the z-direction coordinate of the center of gravity in the AUV body coordinate system; R is the transformation matrix; The AUV horizontal plane dynamics equation (8) is transformed into equation (9): Where: M = M RB +M A ,C=C RB (υ)+D,f(t)=-M -1 d; Define the AUV state variable as x h1 =η,x h2 =υ,x h3 =f(t), and Equation (9) is described in state space form as: The expanded state observer is constructed according to the expanded state space: Where: l h1 ,l h2 ,l h3 is the observer gain matrix, h1, h2, h3 are subscripts to distinguish different state variables; Combining Equation (10) and Equation (11), the dynamic equation of the extended state observer is established as: Where: is the state variable x h1 Observation error.

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