Underwater vehicle docking recovery motion control method stable in specified time

Abstract

The invention discloses an underwater vehicle docking recovery motion control method stable in specified time. The method comprises the following steps: establishing a motion model of an underwater vehicle; on the basis of the established motion model, according to the relative positions and postures of the underwater vehicle and the recycle bin, the expected posture and the expected position of the underwater vehicle in the docking process are determined, and a path planning track of the underwater vehicle in the docking state is determined; determining a specified time parameter of a docking recovery process according to the expected attitude, the expected position and the path planning trajectory of the underwater vehicle; according to the expected velocity vector, the expected pose vector, the specified time parameter and the control parameter, designing a specified time stable sliding mode controller; and based on a specified time stable sliding mode controller, underwater vehicle docking recovery motion control is carried out, so that the attitude and position of the underwater vehicle reach a stable state within a specified time. According to the invention, the accuracy, stability and success rate of docking recovery can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of underwater vehicle docking and recovery motion control, specifically relating to a motion control method for underwater vehicle docking and recovery that is stable for a specified time. Background Technology

[0002] Unmanned underwater vehicles (UUVs) are intelligent marine equipment capable of performing tasks underwater in place of humans, playing a vital role in resource exploration, salvage and rescue, seabed mapping, ecological protection, and marine surveys. However, due to the limited energy carried by UUVs, they need to periodically return to docking stations for refueling during underwater operations and missions, providing a necessary foundation for the long-term, efficient operation of unmanned underwater vehicles.

[0003] The underwater vehicle docking and recovery system consists of a recovery dock, a guidance system, and the underwater vehicle. The underwater vehicle determines the location of the recovery dock through the guidance system and accurately enters the dock using high-precision motion control, achieving docking and recovery. Motion control of the underwater vehicle is particularly critical during the docking and recovery process. The underwater vehicle's attitude and position need to reach a stable state before arriving at the dock to ensure accurate entry. If the position and attitude fail to reach a stable state before reaching the dock, the underwater vehicle will deviate from the dock, leading to docking and recovery failure. To address these issues, effective underwater vehicle control methods are needed to ensure that the attitude and position reach a stable state within a specified time, improving docking and recovery accuracy and success rate.

[0004] To address the needs of underwater vehicles (UVs) returning to docking stations for energy replenishment, information transmission, and mission configuration, a docking and recovery motion control method was designed to ensure accurate and stable entry into the recovery dock. With the increasing demand for autonomous energy replenishment and continuous operation of UVs, docking and recovery motion control has received widespread attention and become a research hotspot. To meet the high precision and stability requirements of UV docking and recovery motion control, it is urgent to research a docking and recovery motion controller to eliminate attitude and position errors between the UV and the recovery cage, and maintain attitude and position stability. This has significant practical implications for successful docking and recovery of UVs.

[0005] Because the relative distance between the underwater vehicle and the recovery dock is limited, the underwater vehicle's attitude and position need to reach a stable state before arriving at the dock during the docking and recovery process. This is to eliminate relative errors in attitude and position and achieve successful docking and recovery. Therefore, in practical applications, employing docking and recovery motion control methods to ensure that the underwater vehicle's position and attitude reach a stable state within a specified time is crucial for accurately and stably completing the docking and recovery motion control.

[0006] Existing docking and recovery control methods suffer from uncontrollable stabilization time, and their stability and docking and recovery success rate need further improvement. Summary of the Invention

[0007] The purpose of this invention is to provide a motion control method for docking and recovery of underwater vehicles that is stable within a specified time, thereby overcoming the shortcomings of existing technologies where the stabilization time is uncontrollable. This method enables underwater vehicles to reach a stable docking and recovery state within a specified time, improving the accuracy, stability, and success rate of docking and recovery, and reducing the economic losses caused by the failure of docking and recovery of unmanned underwater vehicles.

[0008] To achieve the above objectives, the present invention employs the following technical solution: A time-stabilized underwater vehicle docking and recovery motion control method includes: Establish a motion model for the underwater vehicle; Based on the established motion model, the desired attitude and position of the underwater vehicle during the docking process are determined according to the relative position and attitude of the underwater vehicle and the recovery station, and the path planning trajectory of the underwater vehicle in the docking state is determined. Based on the underwater vehicle's desired attitude, desired position, and planned trajectory, determine the specified time parameters for the docking and recovery process; Design a time-stabilized sliding mode controller based on the desired velocity vector, desired pose vector, specified time parameters, and control parameters; Based on a time-stabilized sliding mode controller, motion control for underwater vehicle docking and recovery is performed to ensure that the attitude and position of the underwater vehicle reach a stable state within a specified time.

[0009] Furthermore, the motion model of the underwater vehicle is represented as follows: ; in, ; For generalized mass matrix; It is a matrix generated by the additional inertial effects caused by fluid dynamics; It is the rigid body inertia matrix determined by the mass and geometry of the underwater vehicle itself; ; Represents the total Coriolis force matrix; Here are the Coriolis force and centripetal force matrices for a rigid body; The matrix for the additional mass Coriolis force and centripetal force; Here is the damping matrix; Let be the generalized velocity vector, where , , Let be the linear velocity components, representing the velocity along the carrier coordinate system. , , linear velocity in the direction, , , Let be the angular velocity components, representing the angular velocity around the carrier coordinate system. , , Angular velocity of the axis; The restoring force is related to the gravity and buoyancy of the underwater vehicle and satisfies the pose vector. ; , and These are the heading angle, pitch angle, and roll angle of an underwater vehicle, respectively, indicated by the superscript. Indicates transpose; As environmental disturbance forces, among which , , Let be linear force components, representing the forces along the carrier coordinate system. , , Directional control , , Let be the rotational torque, and represent the torques along the carrier coordinate system. , , Directional control torque; It is the overall control.

[0010] Furthermore, the parameters in the motion model of the underwater vehicle satisfy the following conditions: Generalized mass matrix It is symmetric positive definite and satisfies ; Total Coriolis force matrix It is obliquely symmetrical, that is , , Represents a space consisting of 6-dimensional real vectors; Damping matrix It is positive definite, that is... , .

[0011] Furthermore, based on the relative positions and attitudes of the underwater vehicle and the recovery station, the desired attitude and position of the underwater vehicle during docking are determined, and the path planning trajectory of the underwater vehicle in the docking state is determined, including: The desired attitude includes the desired heading angle, desired pitch angle, and desired depth; the desired position includes... Desired position of axis Desired position of axis Desired position of axis; The heading angle of the recycling bin entrance and pitch angle The desired heading angle and desired pitch angle at the docking end of the underwater vehicle, while ensuring that the desired roll angle of the underwater vehicle is... ; Center the opening of the recycling bin depth As an underwater vehicle in docking state The desired position of the axis is determined by the current horizontal coordinates of the cage opening at the recycling station. As Desired position of axis Desired position of axis, and from coordinates and entrance heading angle Draw a straight line ; Orient the underwater vehicle in a designated straight line Approaching trajectory and reaching the straight line After the straight line Tracking trajectory The length of this path planning trajectory serves as the path planning trajectory between the underwater vehicle and the recovery station. .

[0012] Furthermore, based on the underwater vehicle's desired attitude, desired position, and planned trajectory, the specified time parameters for the docking and recovery process are determined, including: The desired forward velocity of the underwater vehicle during docking and recovery is set to [value missing]. The length of the trajectory through path planning and the expected forward velocity of underwater vehicles Determine the specified time parameters that need to be met during the docking and recovery process. The calculation formula is shown below: ; Based on the specified time parameter Set the specified time parameters for the approach segment and the sliding segment in sliding mode control. and And satisfy ; Select a specified time parameter and Then, another set of design parameters required for the time-stability design is selected. and Its selection rules satisfy: .

[0013] Furthermore, the sliding surface of the sliding mode controller is stabilized over a specified time. The design is as follows: ; ; In the formula, This indicates the tracking error of speed and angular velocity during the motion control process of an underwater vehicle; Let be the desired velocity vector, where , , , , , These represent the expected values ​​of forward velocity, lateral velocity, vertical velocity, roll rate, pitch rate, and yaw rate, respectively. As an auxiliary variable in the design of sliding surfaces, This indicates the position, heading, and attitude tracking errors during the motion control process of an underwater vehicle. Let be the desired pose vector, where , , , , , They represent Desired position of axis Desired position of axis Desired shaft position, desired heading angle, desired pitch angle, and desired roll angle; adjustment items satisfy , It is a natural constant.

[0014] Furthermore, in docking and recycling scenarios, in addition to Except for selecting the appropriate expected value based on the actual docking task, the expected values ​​for all other velocities and angular velocities are set to 0.

[0015] Furthermore, a time-stability sliding mode controller is designed as follows: ; In the formula, The total control force output by the sliding mode controller. Indicates the sign of the variable within the parentheses; An adjustable gain coefficient that satisfies , Environmental disturbance forces Upper bound; adjustment term satisfy .

[0016] Furthermore, the specified time parameters and design parameters are substituted into the specified time stable sliding mode controller; The time-stabilized sliding mode controller is programmed into the control software of the underwater vehicle. Set the mission parameters for docking and recovery motion control, including the position of the recovery station and the heading angle at the recovery station entrance, the initial position, initial heading angle, and forward velocity of the underwater vehicle; The docking and recovery motion control begins. The underwater vehicle generates a path planning trajectory in the docking state based on its relative position information with the recovery station and the heading angle information at the entrance of the recovery station. Then, a time-stabilized sliding mode controller controls the underwater vehicle to navigate towards the recovery station according to the docking and recovery motion trajectory. The time-stabilized sliding mode controller calculates the total control force through periodic control and converts it into the corresponding steering control quantity, so that the underwater vehicle can achieve trajectory tracking and convergence of the desired state before reaching the recovery station, and successfully enter the recovery station to complete the docking and recovery mission.

[0017] A terminal device includes a processor, a memory, and a computer program stored in the memory; when the processor executes the computer program, it implements a motion control method for docking and recovery of an underwater vehicle that is stable for a specified time.

[0018] A computer-readable storage medium storing a computer program; when executed by a processor, the computer program implements a motion control method for docking and recovery of an underwater vehicle that is stable for a specified time.

[0019] Compared with the prior art, the present invention has the following technical features: 1. This invention establishes a motion model for the docking and recovery process, capable of acquiring the desired attitude and position of the underwater vehicle, as well as its relative distance to the recovery dock. Compared with existing motion models, this invention can achieve rapid stabilization of the underwater vehicle's attitude and position within a specified time period by flexibly selecting specified time parameters.

[0020] 2. This invention proposes a motion control method for underwater vehicles that stabilizes at a specified time during the docking and recovery process. By designing a motion controller for the underwater vehicle, the attitude and position are stabilized before reaching the dock. This method can improve the stability of the docking and recovery motion control and increase the success rate of docking and recovery. Attached Figure Description

[0021] Figure 1 Flowchart of motion control for underwater vehicle docking and recovery; Figure 2 A structural diagram of the motion control method for docking and recovery of underwater vehicles; Figure 3 A schematic diagram of the motion control for docking and recovery of an underwater vehicle; Figure 4The underwater vehicle docking and recovery motion control trajectory is shown in simulation scenario 1 of this invention. Figure 5 The above describes the motion control trajectory for the underwater vehicle docking and recovery under simulation scenario 2 in this embodiment of the invention. Detailed Implementation

[0022] This invention addresses the problem of insufficient attitude and position control stability during the docking and recovery of underwater vehicles by proposing a time-stability-based motion control method. This method ensures that the underwater vehicle's attitude and position reach a stable state before reaching the recovery cage, thereby improving the success rate of docking and recovery. The stability time theory upon which this solution is based is described as follows: For an autonomous system , It is a state vector and satisfies , It is a time variable. For system functions; assume there exists a Lyapunov candidate function. ( For the input space, it represents all The space consisting of 3D real vectors For the output space, indicating that the function output is a real value, satisfying... , ,when When the following conditions are met, it can be concluded that the autonomous system is in any... ( When the initial time is indicated, it is possible to achieve the set time. Globally stable at a specified time within a given time period:

[0023] in, These are Lyapunov candidate functions used to measure the system state. The "energy" or "distance from the equilibrium point"; for 3D system state vector; This is the time derivative of the Lyapunov function; Let be the positive parameters to be designed, satisfying ; Let be the desired convergence time constant, which is a time parameter representing the convergence rate of the control system, satisfying . ; It is an exponential function; For about and The power function.

[0024] See Figure 1The present invention provides a time-stable underwater vehicle docking and recovery motion control method, the specific steps of which are as follows: Step 1: Establish a motion model of the underwater vehicle.

[0025] The motion model of the underwater vehicle is represented as follows: (1.1) In the formula, a single dot superscript for a parameter represents its first derivative, and the same applies below; ; The generalized mass matrix includes rigid body inertia and additional mass effects; It is a matrix generated by the additional inertial effects caused by fluid dynamics; It is the rigid body inertia matrix determined by the mass and geometry of the underwater vehicle itself; ; This represents the total Coriolis force matrix, used to describe the inertial torque effect caused by velocity; The Coriolis force and centripetal force matrices of a rigid body are derived from the mass and inertia matrix of the underwater vehicle itself. The determined moment of inertia matrix; The matrix of Coriolis force and centripetal force due to the added mass is determined by the fluid added mass. The resulting inertial torque effect; Here is the damping matrix; Let be the generalized velocity vector, where , , The linear velocity components represent the velocity along the carrier coordinate system ( The axis is on the longitudinal section that is symmetrical to the left and right of the underwater vehicle, and the direction pointing to the direction of the underwater vehicle's movement is positive; The axis is on the central plane of the underwater vehicle, with the right side being positive; Axis perpendicular (Plane, downward is positive) , , linear velocity in the direction, , , Let be the angular velocity components, representing the angular velocity around the carrier coordinate system. , , Angular velocity of the axis; The restoring force is related to the gravity and buoyancy of the underwater vehicle and satisfies the pose vector. ; , and These are the heading angle, pitch angle, and roll angle of an underwater vehicle, respectively, indicated by the superscript. This indicates transposition, the same applies below; As environmental disturbance forces, among which , , Let be linear force components, representing the forces along the carrier coordinate system. , , Directional control , , Let be the rotational torque, and represent the torques along the carrier coordinate system. , , The directional control torque is generally considered to be a constant disturbance, as environmental disturbances are periodically and slowly changing. It is the overall control.

[0026] Rigid body inertia matrix for: (1.2) In the formula, For the mass of the underwater vehicle; It is a skew-symmetric matrix operator; , The center of gravity of the underwater vehicle is in the carrier coordinate system. , , Coordinates on three axes; Let be the moment of inertia matrix of the underwater vehicle relative to the origin (center of buoyancy) of the carrier coordinate system, expressed as: (1.3) In the formula, , , For underwater vehicles with respect to body coordinate system , , Moment of inertia of the shaft; , , yes , , The product of inertia of a plane.

[0027] Additional mass matrix for: (1.4) In the formula, , , For the carrier coordinate system , , The linear additional mass component in the direction represents the additional inertia generated by the accelerating fluid; , , Add an inertial component to the rotation, representing the rotation about the carrier coordinate system. , , The rotation of the shaft accelerates the additional inertia of the fluid; , , , To be The four obtained from the partitioning matrix.

[0028] The parameters in the motion model of the underwater vehicle satisfy the following conditions: (1) Generalized mass matrix It is symmetric positive definite and satisfies ; (2) Total Coriolis force matrix It is obliquely symmetrical, that is , , Represents a space consisting of 6-dimensional real vectors; (3) Damping matrix It is positive definite, that is... , .

[0029] In actual use, the above parameters can be calculated by substituting the specific parameter values ​​of the underwater vehicle used in the docking and recovery mission. The specific parameter values ​​will not affect the sliding mode controller design in the following steps. Step 2: Based on the established motion model, and according to the relative positions and attitudes of the underwater vehicle and the recovery station, determine the desired attitude and desired position of the underwater vehicle during docking, and determine the path planning trajectory of the underwater vehicle in the docking state; wherein the desired attitude includes the desired heading angle, desired pitch angle, and desired depth; the desired position includes... Desired position of axis Desired position of axis Desired position of the axis.

[0030] Step 2-1, as shown in the attached document Figure 3 As shown, the heading angle of the recycling station entrance. and pitch angle The desired heading angle and desired pitch angle at the docking end of the underwater vehicle, while ensuring that the desired roll angle of the underwater vehicle is... .

[0031] Step 2-2, center the opening of the recycling bin. depth As an underwater vehicle in docking state The desired position (desired depth) of the axis is determined by the current horizontal coordinates of the cage opening of the recycling station. As Desired position of axis Desired position of axis, and from coordinates and entrance heading angle Draw a straight line .

[0032] Steps 2-3: Direct the underwater vehicle towards the designated straight line. Approaching trajectory and reaching the straight line After the straight line Tracking trajectory The length of this path planning trajectory serves as the path planning trajectory between the underwater vehicle and the recovery station. .

[0033] Step 3: Determine the specified time parameters for the docking and recovery process based on the underwater vehicle's desired attitude, desired position, and planned trajectory.

[0034] Step 3-1: Set the desired forward velocity of the underwater vehicle during the docking and recovery process. The length of the trajectory through path planning and the expected forward velocity of underwater vehicles Determine the specified time parameters that need to be met during the docking and recovery process. The calculation formula is shown below: (1.5) Step 3-2, based on the specified time parameter Set the specified time parameters for the approach segment and the sliding segment in sliding mode control. and And satisfy ; and In this embodiment, the selection is carried out at a 1:1 ratio, that is... .

[0035] Step 3-3: Select the specified time parameter and Then, another set of design parameters required for the time-stability design is selected. and Its selection rules satisfy: (1.6) Step 4: Design a time-stabilized sliding mode controller based on the desired velocity vector, desired pose vector, specified time parameters, and control parameters.

[0036] Step 4-1: Design the sliding surface of the sliding mode controller. for: (1.7) (1.8) In the formula, For the designed sliding surface; This indicates the tracking error of speed and angular velocity during the motion control process of an underwater vehicle; Let be the desired velocity vector, where , , , , , These represent the expected values ​​of forward velocity, lateral velocity, vertical velocity, roll rate, pitch rate, and yaw rate, respectively. In the docking and recovery scenario, except... Except for selecting the appropriate expected value based on the actual docking task, the expected values ​​for all other velocities and angular velocities are set to 0. As an auxiliary variable in the design of sliding surfaces, This indicates the position, heading, and attitude tracking errors during the motion control process of an underwater vehicle. Let be the desired pose vector, where , , , , , They represent Desired position of axis Desired position of axis The desired shaft position, desired heading angle, desired pitch angle, and desired roll angle are selected as shown in steps 2-1 and 2-2; adjustment items satisfy , It is a natural constant.

[0037] Step 4-2, further design the time-stabilized sliding mode controller as follows: (1.9) In the formula, Indicates the sign of the variable within the parentheses; An adjustable gain coefficient that satisfies , Environmental disturbance forces Upper bound; adjustment term satisfy .

[0038] Step 5: Based on the time-stabilized sliding mode controller, perform underwater vehicle docking and recovery motion control to ensure that the attitude and position of the underwater vehicle reach a stable state within a specified time. This ensures that the attitude and position of the underwater vehicle reach a stable state before reaching the recovery cage, thus avoiding docking and recovery failure caused by the instability of the underwater vehicle's attitude and position.

[0039] The specific implementation process of step 5 includes: Step 5-1: Substitute the specified time parameters and design parameters of the sliding mode controller obtained in Step 3 into the specified time stable sliding mode controller in Step 4.

[0040] Step 5-2: Write the time-stabilized sliding mode controller into the control software of the underwater vehicle through code programming.

[0041] Step 5-3: Set the mission parameters for docking and recovery motion control, including the position of the recovery station and the heading angle at the recovery station entrance, the initial position, initial heading angle, and forward speed of the underwater vehicle.

[0042] Step 5-4: Begin docking and recovery motion control. The underwater vehicle generates a path planning trajectory in the docking state using its relative position information with the recovery station and the heading angle information at the station entrance. Then, a time-stabilized sliding mode controller guides the underwater vehicle to navigate towards the recovery station according to the docking and recovery motion trajectory. The time-stabilized sliding mode controller periodically calculates the total control force. This information is then converted into corresponding steering control quantities, ensuring that the underwater vehicle can track its trajectory and converge to the desired state before reaching the recovery station, thus enabling the underwater vehicle to smoothly enter the recovery station and complete the docking and recovery mission.

[0043] The specific details of the simulation of the docking and recovery motion control of the underwater vehicle are shown in the following examples.

[0044] Simulation Scenario 1: Set the recycle bin location as The entry heading angle is The initial position of the underwater vehicle is The initial heading angle is Forward velocity The parameters for the sliding mode controller are as follows: , , and .

[0045] Simulation results are as follows Figure 4 As shown, under the control of the sliding mode controller, the underwater vehicle can stably enter the recovery station within a specified 22 seconds to achieve docking and recovery.

[0046] Simulation Scenario 2: Set the recycle bin location as The entry heading angle is The initial position of the underwater vehicle is The initial heading angle is Forward velocity The parameters for the sliding mode controller are as follows: , , and .

[0047] Simulation results are as follows Figure 5 As shown, under the control of the sliding mode controller, the underwater vehicle can stably enter the recovery station within a specified 36 seconds to achieve docking and recovery.

[0048] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such 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 this application, and should all be included within the protection scope of this application.

Claims

1. A time-stable motion control method for docking and recovery of an underwater vehicle, characterized in that, include: Establish a motion model for the underwater vehicle; Based on the established motion model, the desired attitude and position of the underwater vehicle during the docking process are determined according to the relative position and attitude of the underwater vehicle and the recovery station, and the path planning trajectory of the underwater vehicle in the docking state is determined. Based on the underwater vehicle's desired attitude, desired position, and planned trajectory, determine the specified time parameters for the docking and recovery process; Design a time-stabilized sliding mode controller based on the desired velocity vector, desired pose vector, specified time parameters, and control parameters; Based on a time-stabilized sliding mode controller, motion control for underwater vehicle docking and recovery is performed to ensure that the attitude and position of the underwater vehicle reach a stable state within a specified time.

2. The underwater vehicle docking and recovery motion control method with a specified time stability according to claim 1, characterized in that, The motion model of the underwater vehicle is represented as follows: ； in, ; For generalized mass matrix; It is a matrix generated by the additional inertial effects caused by fluid dynamics; It is the rigid body inertia matrix determined by the mass and geometry of the underwater vehicle itself; ; Represents the total Coriolis force matrix; Here are the Coriolis force and centripetal force matrices for a rigid body; The matrix for the additional mass Coriolis force and centripetal force; Here is the damping matrix; Let be the generalized velocity vector, where , , Let be the linear velocity components, representing the velocity along the carrier coordinate system. , , linear velocity in the direction, , , Let be the angular velocity components, representing the angular velocity around the carrier coordinate system. , , Angular velocity of the axis; The restoring force is related to the gravity and buoyancy of the underwater vehicle and satisfies the pose vector. ; , and These are the heading angle, pitch angle, and roll angle of an underwater vehicle, respectively, indicated by the superscript. Indicates transpose; As environmental disturbance forces, among which , , Let be linear force components, representing the forces along the carrier coordinate system. , , Directional control , , Let be the rotational torque, and represent the torques along the carrier coordinate system. , , Directional control torque; It is the overall control.

3. The underwater vehicle docking and recovery motion control method with a specified time stability according to claim 1, characterized in that, The parameters in the motion model of the underwater vehicle satisfy the following conditions: Generalized mass matrix It is symmetric positive definite and satisfies ; Total Coriolis force matrix It is obliquely symmetrical, that is , , Represents a space consisting of 6-dimensional real vectors; Damping matrix It is positive definite, that is... , .

4. The underwater vehicle docking and recovery motion control method with a specified time stability according to claim 1, characterized in that, Based on the relative positions and attitudes of the underwater vehicle and the recovery station, the desired attitude and position of the underwater vehicle during docking are determined, and the path planning trajectory of the underwater vehicle in the docking state is determined, including: The desired attitude includes the desired heading angle, desired pitch angle, and desired depth; the desired position includes... Desired position of axis Desired position of axis Desired position of axis; The heading angle of the recycling bin entrance and pitch angle The desired heading angle and desired pitch angle at the docking end of the underwater vehicle, while ensuring that the desired roll angle of the underwater vehicle is... ; Center the opening of the recycling bin depth As an underwater vehicle in docking state The desired position of the axis is determined by the current horizontal coordinates of the cage opening at the recycling station. As Desired position of axis Desired position of axis, and from coordinates and entrance heading angle Draw a straight line ; Orient the underwater vehicle in a designated straight line Approaching trajectory and reaching the straight line After the straight line Tracking trajectory The length of this path planning trajectory serves as the path planning trajectory between the underwater vehicle and the recovery station. .

5. The underwater vehicle docking and recovery motion control method with a specified time stability according to claim 1, characterized in that, Based on the underwater vehicle's desired attitude, desired position, and planned trajectory, the specified time parameters for the docking and recovery process are determined, including: The desired forward velocity of the underwater vehicle during docking and recovery is set to [value missing]. The length of the trajectory through path planning and the expected forward velocity of underwater vehicles Determine the specified time parameters that need to be met during the docking and recovery process. The calculation formula is shown below: ； Based on the specified time parameter Set the specified time parameters for the approach segment and the sliding segment in sliding mode control. and And satisfy ; Select a specified time parameter and Then, another set of design parameters required for the time-stability design is selected. and Its selection rules satisfy: .

6. The underwater vehicle docking and recovery motion control method with a specified time stability according to claim 1, characterized in that, Sliding surface of a time-stabilized sliding mode controller The design is as follows: ； ； In the formula, This indicates the tracking error of speed and angular velocity during the motion control process of an underwater vehicle; Let be the desired velocity vector, where , , , , , These represent the expected values ​​of forward velocity, lateral velocity, vertical velocity, roll rate, pitch rate, and yaw rate, respectively. As an auxiliary variable in the design of sliding surfaces, This indicates the position, heading, and attitude tracking errors during the motion control process of an underwater vehicle. Let be the desired pose vector, where , , , , , They represent Desired position of axis Desired position of axis Desired shaft position, desired heading angle, desired pitch angle, and desired roll angle; adjustment items satisfy , It is a natural constant.

7. The underwater vehicle docking and recovery motion control method with a specified time stability according to claim 6, characterized in that, Design a time-stability sliding mode controller as follows: ； In the formula, The total control force output by the sliding mode controller. Indicates the sign of the variable within the parentheses; An adjustable gain coefficient that satisfies , Environmental disturbance forces Upper bound; adjustment term satisfy .

8. The underwater vehicle docking and recovery motion control method with a specified time stability according to claim 1, characterized in that, Substitute the specified time parameters and design parameters into the specified time stable sliding mode controller; The time-stabilized sliding mode controller is programmed into the control software of the underwater vehicle. Set the mission parameters for docking and recovery motion control, including the position of the recovery station and the heading angle at the recovery station entrance, the initial position, initial heading angle, and forward velocity of the underwater vehicle; The docking and recovery motion control begins. The underwater vehicle generates a path planning trajectory in the docking state based on its relative position information with the recovery station and the heading angle information at the entrance of the recovery station. Then, a time-stabilized sliding mode controller controls the underwater vehicle to navigate towards the recovery station according to the docking and recovery motion trajectory. The time-stabilized sliding mode controller calculates the total control force through periodic control and converts it into the corresponding steering control quantity, so that the underwater vehicle can achieve trajectory tracking and convergence of the desired state before reaching the recovery station, and successfully enter the recovery station to complete the docking and recovery mission.

9. A terminal device, comprising a processor, a memory, and a computer program stored in the memory; characterized in that, When the processor executes the computer program, it implements the underwater vehicle docking and recovery motion control method that is stable for a specified time as described in any one of claims 1-8.

10. A computer-readable storage medium storing a computer program; characterized in that, When the computer program is executed by the processor, it implements the underwater vehicle docking and recovery motion control method that is stable for a specified time as described in any one of claims 1-8.

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