Submersible and positioning control method thereof

Abstract

The invention relates to the technical field of positioning, and provides a submersible and a positioning control method of the submersible. The submersible comprises a submersible main body, a first propeller and a second propeller, the submersible main body is provided with a main propeller, and the submersible main body is provided with a shell; the first propeller is telescopically arranged on the bow part of the shell and is perpendicular to the shell; the second propeller is telescopically arranged at the stern part of the shell and is perpendicular to the shell; when the submersible sails at a high speed, the first thruster and the second thruster are located in the shell, and when the submersible is positioned at a zero sailing speed, the first thruster and the second thruster are located outside the shell. According to the submersible, when the submersible is positioned at the zero navigational speed, the first propeller and the second propeller extend out of the shell, so that the heading angle of the submersible is adjusted, and the submersible is moved to the target position.

Description

TECHNICAL FIELD

[0001] The present application relates to the positioning technical field, and in particular to a submersible and a positioning control method of the submersible. BACKGROUND

[0002] For large submersibles, the external power system is usually constructed by externally hanging multiple types of thrusters in combination in the current engineering practice, so as to realize the positioning function through the cooperative work of the thrusters. However, it is found in the actual application process that when the submersible is in a high-speed navigation state, the thrusters exposed too much to the external environment will damage the integrity of the hydrodynamic shape of the carrier, intensify the flow interference, increase the additional resistance, and thus have an adverse effect on the maneuvering performance and positioning accuracy of the submersible, which seriously restricts the application efficiency of the submersible in complex marine environments. SUMMARY

[0003] The present application provides a submersible and a positioning control method of the submersible, to solve the defect that the positioning method of the submersible affects the navigation performance of the submersible in the prior art.

[0004] The present application provides a submersible, comprising: a submersible main body provided with a main thruster, the submersible main body having a shell; a first thruster telescopically arranged at the bow of the shell and arranged perpendicularly to the shell; and a second thruster telescopically arranged at the stern of the shell and arranged perpendicularly to the shell; wherein the first thruster and the second thruster are located inside the shell when the submersible is in high-speed navigation, and the first thruster and the second thruster are located outside the shell when the submersible is in zero-speed positioning.

[0005] The present application also provides a positioning control method based on the submersible as described above, comprising: obtaining a first deviation between the current position and the target position of the submersible in a flow-free environment, and controlling the first thruster and the second thruster to operate based on the first deviation, so as to make the submersible located at the target position; in a flow environment, establishing a heading controller and a position keeping controller, the heading controller being used to control the first thruster and the second thruster to operate, so as to make the bow of the submersible always face the incoming flow, and the position keeping controller being used to control the main thruster to operate, so as to make the submersible located at the target position.

[0006] According to the positioning control method provided by the application, the step of obtaining a first deviation between the current position of the submersible and the target position in a flow-free environment and controlling the first propeller and the second propeller to operate based on the first deviation so that the submersible is located at the target position comprises: controlling the first propeller and the second propeller to operate based on the optimal turning angle so that the current heading angle of the submersible is the same as the target heading angle; and controlling the first propeller and the second propeller to push the submersible to the target position.

[0007] According to the positioning control method provided by the application, the step of controlling the first propeller and the second propeller to operate based on the optimal turning angle so that the current heading angle of the submersible is the same as the target heading angle comprises: establishing a coordinate system, connecting the current position and the target position to obtain a line segment; calculating an included angle between the line segment and the x-axis based on the principle that the heading angle of the submersible is perpendicular to the line segment; obtaining the current heading angle of the submersible at the current position; obtaining a first turning angle and a second turning angle based on the included angle and the current heading angle; selecting the smaller one of the first turning angle and the second turning angle as the optimal turning angle; and controlling the first propeller and the second propeller to operate so that the bow of the submersible turns the optimal turning angle.

[0008] According to the positioning control method provided by the application, in a flow environment, the step of establishing a position keeping controller comprises: setting a catenary point based on the direction of the resultant force of the incoming flow, wherein the catenary point is opposite to the direction of the resultant force of the incoming flow; obtaining a second deviation between the current position of the submersible and the catenary point; and obtaining a target heading angle of the submersible when the bow of the submersible is directed towards the catenary point based on the second deviation.

[0009] According to the positioning control method provided by the application, in a flow environment, the step of establishing a position keeping controller further comprises: obtaining a first distance between the current position of the submersible and the catenary point and a second distance between the target position and the catenary point; obtaining a third deviation based on the first distance and the second distance; and obtaining a target speed of the submersible based on the third deviation.

[0010] According to the positioning control method provided by the application, in a flow environment, the step of establishing a position keeping controller further comprises: obtaining a fourth deviation between the target speed and the current speed of the submersible; defining a first sliding surface based on the third deviation and the fourth deviation; and obtaining a control law of the submersible based on the first sliding surface.

[0011] The positioning control method provided by the application comprises the following steps: obtaining a current bow angle of the submersible at a current position and a bow angle of the submersible at a catenary point; obtaining a third turning bow angle based on a fifth deviation between the bow angle and the current bow angle and a maximum value of the turning bow angle.

[0012] The positioning control method provided by the application comprises the following steps: obtaining a current bow angle of the submersible at a current position and a bow angle of the submersible at a catenary point; obtaining a third turning bow angle based on a fifth deviation between the bow angle and the current bow angle and a maximum value of the turning bow angle.

[0013] The positioning control method provided by the application comprises the following steps: obtaining a current bow angle of the submersible at a current position and a bow angle of the submersible at a catenary point; obtaining a third turning bow angle based on a fifth deviation between the bow angle and the current bow angle and a maximum value of the turning bow angle.

[0014] The submersible provided by the application comprises a first propeller arranged at the bow of the submersible body and a second propeller arranged at the stern of the submersible body, wherein the first propeller and the second propeller are retractable. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0016] Figure 1 FIG. 1 is a structural schematic diagram of the submersible provided by the application.

[0017] Figure 2 FIG. 4 is a bow turning control strategy diagram of the submersible in a flowless environment.

[0018] Figure 3 FIG. 6 is a catenary point moving schematic diagram.

[0019] Figure 4 FIG. 8 is a simulation effect diagram of the submersible achieving positioning against a skew flow.

[0020] Figure 5This is a schematic diagram of the framework of a finite-time extended state observer.

[0021] Figure 6 This is a technology roadmap for finite-time extended state observers.

[0022] Figure 7 This is a roadmap for sliding mode control technology for submersibles that incorporates a finite-time extended state observer.

[0023] 10. Main thruster; 20. First thruster; 30. Second thruster; 100. Submersible body. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] The following is combined Figures 1-7 The present invention describes a submersible and a method for positioning and controlling the submersible.

[0026] like Figure 1 As shown, in an embodiment of the present invention, the submersible includes: a submersible body 100, a main thruster 10, a first thruster 20, and a second thruster 30. The main thruster 10 is disposed at one end of the submersible body 100 and is used to propel the submersible to move longitudinally. The first thruster 20 and the second thruster 30 are retractably disposed within the submersible body 100 and are arranged perpendicular to the submersible body 100. The first thruster 20 and the second thruster 30 are used to propel the bow of the submersible to turn.

[0027] Specifically, the submersible body 100 has a hull, with a first opening on the bottom surface of the bow and a second opening on the bottom surface of the stern. A first cover plate is provided at the first opening, hinged to the inner wall of the first opening to allow the first opening to be in an open or closed state. A second cover plate is provided at the second opening, hinged to the inner wall of the second opening to allow the second opening to be in an open or closed state. A first thruster 20 and a second thruster 30 are disposed within the hull of the submersible body 100, with the first thruster 20 extending out of the hull through the first opening and the second thruster 30 extending out of the hull through the second opening.

[0028] When the submersible is traveling at high speed, the first thruster 20 and the second thruster 30 are located inside the hull to avoid affecting the submersible's navigation performance. When the submersible is at zero speed and in position, the first thruster 20 and the second thruster 30 extend outside the hull to resist the influence of the incoming flow on the submersible. Specifically, the main thruster 10 provides greater thrust to move the submersible longitudinally, while the first thruster 20 and the second thruster 30 provide less thrust to steer the bow of the submersible, thereby moving the submersible to the target position.

[0029] It should be noted that in the embodiments of the present invention, the positioning of the submersible means that the submersible must not only be moored at the target position, but also that the heading angle of the submersible after mooring must be the same as the heading angle of the target.

[0030] The submersible provided in this embodiment of the invention has a retractable first thruster at the bow of the submersible body and a retractable second thruster at the stern of the submersible body. When the submersible is traveling at high speed, the first and second thrusters can be retracted into the hull to reduce drag; when the submersible is positioned at zero speed, the first and second thrusters can be extended outside the hull to adjust the heading angle of the submersible and move the submersible to the target position.

[0031] This invention also provides a positioning and control method for a submersible, specifically including the following steps: Step 01: In a dry environment, obtain the first deviation between the current position of the submersible and the target position, and control the operation of the first thruster 20 and the second thruster 30 based on the first deviation so that the submersible is located at the target position.

[0032] Specifically, in this embodiment, a flow-free environment refers to a situation where the fluid has little impact on the submersible's heading. In this environment, since the submersible has a longitudinal velocity of 0-1 knots, it is necessary to continuously adjust the submersible's heading angle to ensure that the current heading angle matches the target heading angle. In this embodiment, based on the optimal heading angle, the first thruster 20 and the second thruster 30 are controlled to operate, ensuring that the submersible's current heading angle matches the target heading angle. Then, the first thruster 20 and the second thruster 30 are controlled to propel the submersible to the target position.

[0033] Step 02: In a flowing environment, establish a heading controller and a position holding controller. The heading controller is used to control the operation of the first thruster 20 and the second thruster 30 so that the bow of the submersible is always facing the incoming flow. The position holding controller is used to control the operation of the main thruster 10 so that the submersible is in the target position.

[0034] Specifically, in this embodiment, a flowing environment refers to a situation where the fluid has a significant impact on the submersible's heading. In this environment, the submersible experiences the greatest disturbance during crossflows, and the first thruster 20 and the second thruster 30 are insufficient to resist the incoming flow. Therefore, a positioning control strategy based on the principle of minimizing lateral thrust is designed. Based on this principle, a heading controller and a position-holding controller are designed. In this embodiment, the submersible system is considered an underactuated system, i.e., it only has longitudinal drive and bow-turning drive. The longitudinal drive is achieved by the main thruster 10, and the bow-turning drive is achieved by the first thruster 20 and the second thruster 30. The heading controller is used to make the submersible move like a pendulum in a potential field, ensuring that the bow of the submersible always faces the resultant force of the incoming flow disturbance. The position-holding controller mainly relies on the main thruster 10 to resist the incoming flow disturbance, enabling the submersible to operate in more severe sea conditions and move to the target position.

[0035] The submersible positioning and control method provided in this embodiment of the invention, in a dry environment, relies on the first thruster and the second thruster to make the current heading angle of the submersible the same as the target heading angle, and pushes the submersible to the target position; in a flowing environment, relies on the first thruster, the second thruster and the main thruster to move the submersible to the target position, thus realizing the positioning of the submersible.

[0036] In a dry environment, the steps of obtaining the first deviation between the current position and the target position of the submersible, and controlling the operation of the first thruster 20 and the second thruster 30 based on the first deviation to bring the submersible to the target position include: controlling the operation of the first thruster 20 and the second thruster 30 based on the optimal bow angle to make the current bow angle of the submersible the same as the target bow angle; and controlling the first thruster 20 and the second thruster 30 to push the submersible to the target position.

[0037] Specifically, in this embodiment, positioning the submersible at the target location is accomplished in two main steps. First, the torque of the first thruster 20 and the second thruster 30 is controlled at the current position to rotate the bow of the submersible at the optimal bow angle, thereby adjusting the submersible's attitude so that the current bow angle of the submersible is the same as the target bow angle. Then, the first thruster 20 and the second thruster 30 are controlled to use lateral thrust to move the submersible to the target location.

[0038] Furthermore, in an embodiment of the present invention, the step of controlling the operation of the first thruster 20 and the second thruster 30 based on the optimal bow angle to make the current bow angle of the submersible the same as the target bow angle includes: Establish a coordinate system and connect the current position with the target position to obtain a line segment; based on the principle that the bow of the submersible is perpendicular to the line segment, calculate the angle between the line segment and the x-axis; obtain the current heading angle of the submersible at the current position; based on the included angle and the current heading angle, obtain the first turning angle and the second turning angle; select the smaller value between the first turning angle and the second turning angle as the optimal turning angle, and control the operation of the first thruster 20 and the second thruster 30 to make the bow of the submersible rotate at the optimal turning angle.

[0039] Specifically, such as Figure 2 As shown, a coordinate system is established with the target position O of the submersible as the origin. Let the coordinates of the submersible at its current position be ( ). The coordinates of the target location are ( Then the first deviation between the two is: .

[0040] Connect the submersible's center of gravity at its current position to point O, obtaining line segment OC. The control strategy is that the submersible's heading angle is perpendicular to OC. Based on... The target position OC can be obtained. Angle between axes .

[0041] like Figure 2 As shown, when the bow of the submersible rotates, it can rotate either clockwise or counterclockwise, resulting in the following formulas. .

[0042] in, This is the current heading angle. For the first turning angle, This is the second turning angle.

[0043] The above expression can then be transformed into: .

[0044] . (Formula 1) in, n 1. , n 2 is an intermediate variable. This is a rounding function that performs rounding operations on the variables in Formula 1, following steps ① to ④. Limited to ,get: (Formula 2) Compare and judge according to Formula 2 and The smaller of the values ​​is taken as the optimal bow angle. .

[0045] In actual simulation, such as Figure 2 As shown, when the submersible is in situation A, the dashed line represents its current position, and the solid line represents the position it needs to adjust to. The torque generated by the first thruster 20 and the second thruster 30 controls the bow to rotate counterclockwise by the first turning angle, instead of clockwise by the second turning angle. Similarly, when the submersible is in situation B, the torque generated by the first thruster 20 and the second thruster 30 controls the bow to rotate clockwise by the deflection angle. .

[0046] exist Figure 2 When the submersible is adjusted from the dotted line position to the solid line position, the attitude of the submersible is determined. However, there is still a certain distance between the submersible and the target position. Therefore, under the thrust of the first thruster 20 and the second thruster 30, the submersible is pushed from the adjusted position to the target position.

[0047] It should be noted that in the embodiments described above, the heading angle refers to the absolute direction in which the bow of the submersible points, and the turning angle refers to the angle at which the bow of the submersible rotates.

[0048] In an embodiment of the present invention, the step of establishing a position holding controller in a flowing environment includes: setting a catenary point based on the resultant force direction of the incoming flow, wherein the catenary point is opposite to the resultant force direction of the incoming flow; obtaining a second deviation between the current position of the submersible and the catenary point; and obtaining the target heading angle of the submersible when the bow of the submersible is facing the catenary point based on the second deviation.

[0049] Specifically, such as Figure 3 As shown, Fe represents the direction of the resultant force of the incoming flow, and the "caten point" is defined. The coordinates are The current location of the submersible is The coordinates of the current position are Therefore, we can determine the current position and the "chain point". The second deviation between them is: Therefore, we can determine that the bow of the submersible is facing the catenary. bow angle : .

[0050] Because the designed position-holding controller is based on an underactuated system, i.e., there is always an actuation force... .therefore: in, For the velocity matrix,M The inertia matrix, D Here is the damping matrix. J The position transformation matrix, b The transformation coefficient matrix, τ This is the external control force matrix.

[0051] According to the above formula, we can obtain: in, For the longitudinal velocity acceleration of the submersible, For longitudinal velocity, For the lateral velocity acceleration of the submersible, For lateral velocity, For the turning speed, For the turning torque, For the acceleration of the bow, for The corresponding elements in for The corresponding elements in This refers to external environmental disturbances and unmodeled states.

[0052] Furthermore, in a flowing environment, the steps of establishing a position-keeping controller also include: obtaining a first distance between the current position of the submersible and the catenary point, and a second distance between the target position and the catenary point; obtaining a third deviation based on the first and second distances; and obtaining the target velocity of the submersible based on the third deviation.

[0053] Specifically, the purpose of designing the position-keeping controller is to keep the submersible at the "chain point". The distance between them is always a fixed distance. This refers to the second distance. The submersible's current position relative to the catenary point... The first distance between for: The third deviation is: .

[0054] Furthermore, in a flowing environment, the steps for establishing a position-keeping controller also include: obtaining the fourth deviation between the target velocity and the current velocity of the submersible; defining a first sliding surface based on the third and fourth deviations; and obtaining the control law of the submersible based on the first sliding surface.

[0055] Specifically, the target speed of the submersible is defined as... for: .

[0056] in, This is the upper limit of the submersible's speed. This is a design constant.

[0057] Then, the fourth deviation for: , in, This represents the current speed of the submersible.

[0058] The first sliding surface can be defined as ,in It is a constant. At this point, it is sufficient to design a control law that keeps the submersible's trajectory on the first sliding surface. Taking the derivative with respect to the first sliding surface: .

[0059] in: Will Substituting, we get: To ensure that the submersible's trajectory reaches and remains on the first sliding surface after a certain time, the designed control law must satisfy the following reachability conditions: (Formula 3) in, This is a design constant.

[0060] Therefore, the sliding mode control law can be selected as: Substituting it into formula 3, we get: However, the speed of a submersible is usually unmeasurable, and environmental disturbances are also unmeasurable. They can only be estimated through methods such as state observers and adaptive techniques.

[0061] For ease of representation, we can define: ,in, f 1 represents the longitudinal control force.

[0062] Its estimated value is denoted as: The critical values ​​for estimation error are: At this moment, the record The longitudinal control law of the submersible can be obtained as follows: In an embodiment of the present invention, in a flowing environment, the step of establishing a heading controller includes: obtaining the current heading angle of the submersible at its current position and the heading angle of the submersible when it is located at the catenary; and obtaining a third heading angle based on the fifth deviation between the heading angle and the current heading angle and the maximum value of the turning angle.

[0063] Specifically, the fifth difference for: ,in, This is the current heading angle. This is the heading angle.

[0064] .

[0065] in, This is the third bow angle. This is the maximum value of the bow angle. This is a design constant.

[0066] Furthermore, the steps for establishing the heading controller also include: obtaining the fourth bow angle when the submersible's bow rotates to the target position from its current position; obtaining the sixth deviation based on the difference between the third and fourth bow angles; defining the second sliding surface based on the fifth and sixth deviations; and obtaining the bow control law based on the second sliding surface.

[0067] Specifically, the sixth deviation for: ,in, This is the fourth bow angle.

[0068] The second sliding surface is: Similar to the design process of the position holding controller, the final steering control law is obtained: in: in, f 2 represents the steering control torque.

[0069] And there is, , .

[0070] In an embodiment of the present invention, in a flowing environment, the steps of establishing a heading controller and a position holding controller further include: adjusting the position of the catenary point based on the target heading angle, wherein the catenary point is located on a circle with the current position as the center and a first distance as the radius.

[0071] Specifically, by designing position holding controllers and heading controllers, only heading control based on minimizing lateral thrust is achieved. To achieve positioning control of the submersible, the position of the "chain point" only needs to be updated appropriately.

[0072] like Figure 3 As shown, let the target position of the submersible be... The coordinates of the target location are Then the "chain point" should be along the path of... With center at and radius at, The circular movement, that is in, For the target heading angle, through continuous updating Make Move to the appropriate position and apply the update law: in, The heading angle of the submersible when it is at the catenary point. To ensure a smooth tracking process, It is a very small constant.

[0073] Figure 4 For the simulation using the positioning control method provided in this embodiment of the invention, the maximum incoming flow velocity was set to 2 knots, the current bow angle of the submersible was +45°, the current speed of the submersible was 0, and the speed generated by the still water thrust of the main thruster 10 was set to be no greater than 1 knot, with good balance. The current position of the submersible was (0, 0, 40), the target position was (50, 50, 40), and the position control accuracy was 9.41 m. The simulation results are as follows. Figure 4 As shown, the starting point of the curve is the current position, and the ending point of the curve is the target position.

[0074] Furthermore, in order to shorten the convergence time of the position holding controller and the heading controller and improve the response speed of the submersible during positioning, the positioning control method provided in this embodiment of the invention also designs a finite-time extended state observer and a sliding mode controller combined with the finite-time extended state observer.

[0075] Specifically, the underwater environment is complex, and the submersible model suffers from uncertainties and inaccuracies in its modeling, which can be expressed as: in, For the uncertain part, and This is the nominal model. Auxiliary variables are set. , To obtain a mathematical model of a large submersible: in Obtain the derivative of the desired trajectory , .

[0076] like Figure 5 and Figure 6 As shown, a finite-time extended state observer is designed, wherein, , , The values ​​are, in order, the location value estimated by the observer, the auxiliary variable value, and the total disturbance value.

[0077] Furthermore, the design principle of the observer is: the observation error of the observer hour This makes Changes occur, which in turn affect value, leading to In addition to the effects of external forces, it is also affected by observer errors. Indirectly Influence The size, thus making The value changes. When the observer estimate... When the actual value can be tracked, that is , The value is stable, and correspondingly Unaffected and Its changes are only affected by The impact, and the corresponding Also because , It is only affected by external forces (torques), and has the same effect as the actual system, enabling the estimation of the state.

[0078] In summary, the observer takes the following form: in , , , . , , , , It is a sufficiently small positive value. This is a positive constant that is set.

[0079] The observers assigned to each degree of freedom are shown below: Vertical: Horizontal: Vertical: Swaying: Bow rocking: The observer gain is designed to satisfy the following matrix as a Hurwitz matrix.

[0080] Then you can obtain and Observations and The observer estimates the lumped disturbance. and auxiliary variables Convergence time satisfy: The relevant variables in the above equation are determined by the designed observer parameters. , , , Decision, of which , The largest eigenvalue, It is the smallest eigenvalue. , , , For a non-singular symmetric positive definite matrix, the above parameters satisfy: , , .

[0081] like Figure 7 As shown, combining the finite-time extended state observer designed above, the tracking error is defined. in For the actual trajectory, The desired trajectory is determined. The third sliding surface is designed as follows: Design parameters in the formula , , , The controller is designed based on the third sliding surface as follows: The above formula , , , The controllers assigned to each degree of freedom are shown below: Controllers assigned to each degree of freedom: Total convergence time Including the time to reach the third sliding surface Convergence time of the third sliding surface ,in, Change The size can adjust the convergence time.

[0082] Parameter meaning: Design control gain Guarantee each and It's Hurwitz, the choice. , , Simultaneously set the matrix , , , All are positive definite matrices, satisfying the equation , in , , , , It is a sufficiently small positive value. , .

[0083] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A submersible, characterized in that, include: The submersible body is equipped with a main thruster, and the submersible body has a shell; The first thruster is retractably mounted at the bow of the housing and is perpendicular to the housing; The second propeller is telescopically mounted on the stern of the housing and is perpendicular to the housing. Specifically, when the submersible is traveling at high speed, the first thruster and the second thruster are located inside the hull; when the submersible is at zero speed, the first thruster and the second thruster are located outside the hull.

2. A positioning and control method for a submersible based on claim 1, characterized in that, include: In a dry environment, the first deviation between the current position of the submersible and the target position is obtained, and the operation of the first thruster and the second thruster is controlled based on the first deviation to make the submersible stand at the target position; In a flowing environment, a heading controller and a position holding controller are established. The heading controller is used to control the operation of the first thruster and the second thruster so that the bow of the submersible is always facing the incoming flow. The position holding controller is used to control the operation of the main thruster so that the submersible is located at the target position.

3. The positioning control method according to claim 2, characterized in that, The step of obtaining a first deviation between the current position and the target position of the submersible in a dry environment, and controlling the operation of the first thruster and the second thruster based on the first deviation to position the submersible at the target position includes: Based on the optimal bow angle, control the operation of the first and second thrusters to make the current bow angle of the submersible the same as the target bow angle; Control the first and second thrusters to propel the submersible to the target position.

4. The positioning control method according to claim 3, characterized in that, The step of controlling the operation of the first and second thrusters based on the optimal bow angle to make the current bow angle of the submersible the same as the target bow angle includes: Establish a coordinate system and connect the current position with the target position to obtain a line segment; Based on the principle that the bow angle of the submersible is perpendicular to the line segment, calculate the angle between the line segment and the x-axis; Obtain the current heading angle of the submersible at its current position; Based on the included angle and the current heading angle, the first turning angle and the second turning angle are obtained; The smaller of the first and second turning angles is selected as the optimal turning angle, and the first and second thrusters are controlled to rotate the bow of the submersible to the optimal turning angle.

5. The positioning control method according to claim 2, characterized in that, In a flowing environment, the steps to establish a position-keeping controller include: Based on the direction of the resultant force of the incoming flow, a catenary point is defined, which is opposite to the direction of the resultant force of the incoming flow; Obtain the second deviation between the current position of the submersible and the catenary point; Based on the second deviation, the target heading angle of the submersible is obtained when the bow of the submersible is facing the catenary point.

6. The positioning control method according to claim 5, characterized in that, In a flowing environment, the steps for establishing a position-keeping controller also include: Obtain the first distance between the current position of the submersible and the suspension point, and the second distance between the target position and the suspension point; Based on the first distance and the second distance, a third deviation is obtained; The target speed of the submersible is obtained based on the third deviation.

7. The positioning control method according to claim 6, characterized in that, In a flowing environment, the steps for establishing a position-keeping controller also include: Obtain the fourth deviation between the target velocity and the current velocity of the submersible; Based on the third deviation and the fourth deviation, a first sliding surface is defined; Based on the first sliding surface, the control law of the submersible is obtained.

8. The positioning control method according to claim 5, characterized in that, In a flowing environment, the steps to establish a heading controller include: Obtain the current heading angle of the submersible at its current position and the heading angle when the submersible is at the catenary point; The third turning angle is obtained based on the fifth deviation between the heading angle and the current heading angle, and the maximum value of the turning angle.

9. The positioning control method according to claim 8, characterized in that, In a flowing environment, the steps for establishing a heading controller also include: Obtain the fourth bow angle when the submersible has rotated from its current position to the target position; The sixth deviation is obtained based on the difference between the third and fourth bow angles; Based on the fifth deviation and the sixth deviation, a second sliding surface is defined; Based on the second sliding surface, the bow control law is obtained.

10. The positioning control method according to claim 7, characterized in that, In a flowing environment, the steps for establishing a heading controller and a position-keeping controller also include: Based on the target heading angle, the position of the catenary point is adjusted, wherein the catenary point is located on a circle with the current position as the center and the first distance as the radius.

Images