Time-varying formation transformation control method for water unmanned surface vehicle based on regional control

Abstract

The application discloses a time-varying formation transformation control method for water unmanned surface vehicle based on regional control, which comprises the following steps: constructing a time-varying coordination mechanism of the water unmanned surface vehicle formation, constructing path tracking and obstacle avoidance capability of a single unmanned surface vehicle, formulating a potential field quantitative expression according to an obstacle environment, determining a formation transformation mode, and evaluating the safety and flexibility of the formation system, so that the control method designed for the unmanned surface vehicle formation can guarantee the safety and flexibility of obstacle avoidance and formation transformation. Through the method and system, the navigation precision of the unmanned surface vehicle can be dynamically adjusted according to the environmental constraints and the change of the internal structure of the formation, the environmental adaptability of the unmanned surface vehicle is significantly improved, and the flexibility of the time-varying formation and the diversity of the task execution are also improved.

Description

Technical Field

[0001] This invention relates to a time-varying formation control method for unmanned surface vessels (USVs) that considers complex external obstacle environments and real-time collision avoidance by internal crew members without a fixed internal formation structure, and belongs to the field of USV control technology. Background Technology

[0002] With the continuous development of marine resources, countries around the world are constantly strengthening the research and development of unmanned marine equipment. Unmanned surface vessels (USVs), due to their strong autonomy, high reliability, and flexible maneuverability, can play a multifaceted role in reconnaissance, strike, and support missions. However, the operational capabilities of a single USV exhibit limitations in the face of vast marine environments and large-scale mission scenarios, including limited operational range and support for only a single type of payload. Therefore, research focus has gradually shifted from single USVs to multi-USV collaboration, with continuous efforts in theoretical research and engineering applications. Meanwhile, multi-agent cooperative control theory can significantly compensate for the shortcomings of single-vessel capabilities, fully considering the needs of formation collision avoidance and formation connectivity, greatly improving the sustainability and scalability of marine operations. Furthermore, in existing research, formation maintenance or formation change control relies on a pre-defined absolute formation. When frequent formation changes are required in complex environments, the formation's fault tolerance, flexibility, and scalability are poor. Especially when the formation size is large, there are problems of high computational load and difficulty in formation changes. Therefore, we propose a time-varying cooperative formation mechanism, establish a control model and realize the coordinated cooperation task among individuals using a certain potential field motion rule. In combination with the formation, we formulate a quantitative expression of the potential field for different obstacle avoidance environments, different types and positions of obstacles, as well as the size and number of individuals in the formation system, in order to determine the formation transformation mode.

[0003] To further improve the obstacle avoidance capabilities, formation maintenance, and flexible formation transformation capabilities of unmanned surface vessels (USVs) within a formation, a time-varying formation transformation control method based on region control theory is proposed. Under this method, USVs possess a certain degree of individual freedom while maintaining formation, overcoming the limitations of the "rigid" formations in previous formation control approaches. The formation can change its formation in real time according to the characteristics of different obstacles and quickly restore the initial formation after obstacle avoidance. Summary of the Invention

[0004] In response to the above-mentioned improvement needs of existing technologies, this application proposes a time-varying formation transformation control method for unmanned surface vessels based on regional control. The navigation accuracy of the unmanned vessels can be dynamically adjusted according to changes in environmental constraints and the internal structure of the formation, which significantly improves the environmental adaptability of individual unmanned vessels, as well as the flexibility of time-varying formations and the diversity of missions performed.

[0005] A time-varying formation transformation control method for unmanned surface vessels based on area control includes the following steps:

[0006] Step S1: Constrain the mathematical model of the unmanned surface vessel and construct a time-varying cooperative mechanism for the unmanned surface vessel formation;

[0007] Step S2: Introduce a dynamic window algorithm to build the path tracking and obstacle avoidance capabilities of a single unmanned surface vessel;

[0008] Step S3: Based on the regional control theory, determine the formation transformation method by formulating a quantitative expression for the potential field according to the obstacle environment;

[0009] Step S4: Evaluate the safety and flexibility of the formation system, and assess whether the control method designed for the unmanned surface vessel formation can ensure the safety and flexibility of obstacle avoidance and formation changes.

[0010] A time-varying formation transformation control system for unmanned surface vessels (USVs) based on area control is provided to implement the aforementioned time-varying formation transformation control method for USVs based on area control. The system includes the following units:

[0011] The time-varying cooperative mechanism unit is used to constrain the mathematical model of the unmanned surface vessel and construct a time-varying cooperative mechanism for the unmanned surface vessel formation.

[0012] The tracking and obstacle avoidance planning unit is used to introduce a dynamic window algorithm to build the path tracking and obstacle avoidance capabilities of a single unmanned surface vessel.

[0013] The formation transformation determination unit is used to determine the formation transformation method based on the regional control theory and the quantitative expression of the potential field in the obstacle environment.

[0014] The formation system evaluation unit is used to evaluate the safety and flexibility of the formation system, and to assess whether the control method designed for the unmanned surface vessel formation can ensure the safety and flexibility of obstacle avoidance and formation changes.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0016] In situations where the internal structure of the formation is not fixed, a time-varying collaborative mechanism among the formation, the environment, and the characteristics of the unmanned surface vessel (USV) is constructed. Obstacle avoidance and planning are performed using a dynamic window algorithm, encouraging USVs to avoid obstacles and move towards the target at the maximum possible speed during local motion. Compared to the traditional "leader-follower" framework, area control theory and collision avoidance potential energy functions break through the limitations of "rigid" formations. Formation members can dynamically adjust their navigation accuracy according to environmental constraints and changes in the internal structure of the formation, significantly improving the environmental adaptability of individual USVs and enhancing the flexibility and versatility of time-varying formations for mission execution. Attached Figure Description

[0017] Figure 1 This is a flowchart of the time-varying formation transformation control method for unmanned surface vessels based on regional control according to the present invention.

[0018] Figure 2 This is the overall conceptual design drawing of the time-varying formation of the present invention.

[0019] Figure 3 This is a schematic diagram of the difference model.

[0020] Figure 4 This is a framework diagram of the dynamic window algorithm.

[0021] Figure 5 This is a conceptual diagram of the regional path tracking of the present invention.

[0022] Figure 6 This is a diagram of the collision avoidance potential energy function model of the present invention.

[0023] Figure 7 This is a simulation diagram of the trajectory of the unmanned surface vessel of the present invention in a complex obstacle environment.

[0024] Figure 8 This is a swarm diagram showing the relative positions of swarm members in a complex obstacle environment.

[0025] Figure 9 This is a time-history curve showing the velocity correlation of formation members in a complex obstacle environment.

[0026] Figure 10 This is a structural diagram of the time-varying formation transformation control system for unmanned surface vessels based on regional control according to the present invention. Detailed Implementation

[0027] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0028] Those skilled in the art will understand that, unless otherwise stated, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the word “comprising” as used in this application's specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or wireless coupling. The measures “and / or” as used herein include all or any units and all combinations of one or more associated listed items.

[0029] like Figure 1 As shown, this embodiment of the invention provides a time-varying formation transformation control method for unmanned surface vessels based on area control, including the following steps:

[0030] Step S1: Constrain the mathematical model of the unmanned surface vessel and construct a time-varying cooperative mechanism for the unmanned surface vessel formation;

[0031] Step S2: Introduce a dynamic window algorithm to build the path tracking and obstacle avoidance capabilities of a single unmanned surface vessel;

[0032] Step S3: Based on the regional control theory, determine the formation transformation method by formulating a quantitative expression for the potential field according to the obstacle environment;

[0033] Step S4: Evaluate the safety and flexibility of the formation system, and assess whether the control method designed for the unmanned surface vessel formation can ensure the safety and flexibility of obstacle avoidance and formation changes.

[0034] In step 1, a time-varying collaborative mechanism for surface unmanned surface vessels (USVs) is constructed. An optimized "leader-follower" framework is adopted, combined with regional control theory, difference set theory, and artificial potential field theory, to build a time-varying conceptual model of the formation. Furthermore, a formation transformation function is abstracted to reflect, for example,... Figure 2 The overall conceptual design of the time-varying formation is shown.

[0035] In a preferred embodiment, step S1: constraining the mathematical model of the unmanned surface vessel (USV) to construct a time-varying cooperative mechanism for USV formation, specifically including:

[0036] Step S11: Establish the kinematics and dynamics model of the unmanned surface vessel:

[0037] (1)

[0038] Wherein, the unmanned surface vessel's position vector is , representing the coordinates and heading angle in the geodetic coordinate system, and the velocity vector. , representing the longitudinal velocity, lateral velocity, and bow angle change rate of the unmanned surface vessel in the body coordinate system; For rotation matrix, The inertial force matrix, The Coriolis force and centripetal force matrix, The damping force matrix is... For power input, The environmental disturbance term is defined as follows:

[0039] (2)

[0040] (3)

[0041] (4)

[0042] (5)

[0043] (6)

[0044] in , , ( Reference The numbers () represent the hydrodynamic coefficients related to the maneuverability of a surface vessel in each degree of freedom, namely longitudinal, transverse, and bow angle. For the mass of the unmanned surface vessel; for the hydrodynamic coefficients estimated by model tests and empirical formulas, corresponding dimensional conversions are required;

[0045] Step S12: Construct the difference set model. Taking a circular formation as an example, define the difference set space for the k-th unmanned surface vessel. That is, the safe zone that the k-th unmanned surface vessel can enter within the formation, as shown in the difference model. Figure 3 As shown, the calculation formula is as follows:

[0046] (7)

[0047] in, For the Navigator unmanned surface vessel, For the unmanned surface vessels in the formation, excluding the follower A collection of individual unmanned surface vessels outside of the designated areas. This is the set of safe zones containing both stationary and moving obstacles in the environment, where m and n represent the quantities of each.

[0048] Calculate the difference region space of the formation It should be able to accommodate at least all formation members, that is:

[0049] (8)

[0050] in The proportion of individual formation space, i.e., the formation region, is related to the difference space and the capacity of individual formations. This is the proportion of the difference space to the total formation region. When the safe zone space for a single unmanned surface vessel is smaller than that for a single unmanned surface vessel, the formation needs to be changed to accommodate all individuals. The formation change function is as follows:

[0051] (9)

[0052] in, , , representing the sudden increase in the turning angle in the heading direction and the abrupt change in the lateral movement direction, respectively; through this function, the constraints of formation transformation with time t, the unmanned surface vessel itself, and the number of individuals in the formation are established. and the area radius of individual unmanned surface vessels The relationship between them.

[0053] In a preferred embodiment, such as Figure 4 As shown, step S2: Introducing the dynamic window algorithm to build the path tracking and obstacle avoidance capabilities of a single unmanned surface vessel (USV), specifically including: using the dynamic window (DWA) algorithm for local obstacle avoidance planning to realize trajectory tracking and obstacle avoidance control of a single USV.

[0054] Define the velocity space of the unmanned surface vessel as Based on the speed performance constraints of unmanned surface vessels Velocity and acceleration coordination constraints The velocity search space is calculated. ;in and Let represent linear acceleration and angular acceleration, respectively. By sampling the velocities that meet the constraints over time, the corresponding trajectory can be obtained. These represent the current velocities in the velocity space; the evaluation function. The sampled trajectories are scored, and the velocity space corresponding to the optimal trajectory is selected as the algorithm's output. The corresponding trajectory is then used as the expected trajectory for the next time step.

[0055]

[0056] Direction angle function Used to evaluate the angular error between the predicted trajectory's end heading and the line connecting the trajectory's end to the target point, prompting the unmanned surface vessel to move towards the target; obstacle distance evaluation function. The evaluation function assesses the distance between the predicted trajectory endpoint and the nearest obstacle, penalizing sampling points close to obstacles to reduce the probability of collision and encourage the unmanned surface vessel (USV) to avoid obstacles; a velocity excitation evaluation function is also included. Evaluate the magnitude of the linear velocity at each moment on the predicted trajectory, encourage the unmanned surface vessel to approach the target point at its maximum linear velocity, and encourage the unmanned surface vessel to reach the target quickly; , and Each has its own weight.

[0057] like Figure 5 The diagram shown illustrates a regional path tracking concept. It optimizes the "leader-follower" framework by constructing an external potential field based on a regional control method to ensure all formation members converge within the formation. In this invention, the leader is defined as a "region," and followers converge to a designated "region." The unmanned surface vessel (USV) is controlled to track the target's "movement domain," which is the difference space designed in step S12. Instead of a strict target point, the goal is to enable the unmanned surface vessel (USV) to navigate within a "movement domain" trajectory. When there is external environmental interference, it can converge to the desired "movement domain", thereby reducing the frequent actions of the USV's actuators and reducing energy consumption.

[0058] In a preferred embodiment, step S3: Based on regional control theory, and according to the quantitative expression of the potential field of the obstacle environment, the formation transformation method is determined, specifically including:

[0059] Step S31: Define the objective function for the "mobility domain" as follows:

[0060] (14)

[0061] in, Let be a scalar function with continuous first-order partial derivatives. The number of objective functions; , , This is the location information matrix for the unmanned surface vessel. It is the reference azimuth point of the desired "region". It is a time-varying nonsingular scaling factor, and both are bounded time functions;

[0062] For an unmanned surface vessel (USV), considering only its three degrees of freedom motion in the horizontal plane—swell, yaw, and yaw—the desired state vector is derived from... , , The desired "mobility domain" must match the corresponding dimension, i.e. If we degenerate it into a circular constraint, the objective functions are defined as follows:

[0063] (15)

[0064] (16)

[0065] (17)

[0066] in, It is the boundary of the "mobile domain". Coordinate axes within the "expected domain" direction The coordinate values; Coordinate axes within the "expected domain" direction The coordinate values; This represents the heading angle value within the "expected domain," with a subscript of 0 indicating the reference azimuth point.

[0067] Define time-varying nonsingular scaling factor for:

[0068] (18)

[0069] in, for scaling factor, for scaling factor, for The scaling factor means that different scaling factors can be set for position and attitude respectively, achieving decoupled control; when the scaling factor function... When the function value changes over time, the volume of the desired "moving domain" will also change, so the unmanned surface vessel (USV) can track the time-varying "moving domain". This means that the controller can adopt different strategies at different stages, and the USV has a certain degree of path adaptation.

[0070] but , It can be represented as:

[0071]

[0072] The potential function for a single desired "mobility domain" is defined as follows:

[0073]

[0074]

[0075] Step S32: Based on the artificial potential field method, design an unmanned surface vessel collision avoidance potential energy function model to construct the potential field inside the formation to ensure that the members inside the formation do not collide;

[0076] Radiuses were set around the unmanned surface vessel as follows: and The restricted and buffer zones, the current distance between unmanned surface vessels is A collision avoidance potential energy function model was constructed by referencing the design method of artificial potential energy functions, and a piecewise potential field was defined for each unmanned surface vessel accordingly. At this point, all unmanned surface vessels satisfy the "mobile domain" requirement. Constrained and unaffected by the regional control potential field.

[0077] (25)

[0078] The total collision avoidance potential energy function can be expressed by the following formula:

[0079] (26)

[0080] Collision avoidance error It can be written as:

[0081] (27)

[0082] Step S33: Derivation of control algorithm, controlling the unmanned surface vessel to track the moving target "area", so that the position and heading angle of the unmanned surface vessel can eventually converge to the desired "movement domain" under the premise of avoiding collisions with each other.

[0083] Based on regional error Collision avoidance error We define the following valid reference vectors. :

[0084]

[0085] in, It is a positive constant; Representative vector The reference forward speed, reference lateral speed, and reference turning angular velocity are not the actual measured speeds, but rather the expected speeds calculated from the desired moving domain tracking task, area error, and collision avoidance error, and are used to construct the tracking error. Representation matrix The inverse matrix is ​​defined in the same way as in Formula 2; For matrix The derivative matrix; For matrix The inverse matrix, based on and The following tracking error vector is defined for the unmanned surface vessel:

[0086] (29)

[0087] (30)

[0088] Based on the equations of motion of the unmanned surface vessel (USV), the open-loop error equation of the USV can be described by the following formula:

[0089] (31)

[0090] in And there are

[0091]

[0092]

[0093] The unmanned surface vessel (USV) formation switching controller is designed as follows:

[0094] (32)

[0095] Among them, parameters The update rule is In this rule, For a symmetric positive definite matrix, in Equation 31, For the switching gain control item of the controller, Depend on Derivation, in which And satisfy Combining equations 31 and 32, the closed-loop dynamic control system of the unmanned surface vessel can be obtained as follows:

[0096] (33)

[0097] in .

[0098] In a preferred embodiment, step S4: evaluating the safety and flexibility of the formation system, assessing whether the control method designed for the unmanned surface vessel formation can guarantee the safety and flexibility of obstacle avoidance and formation changes, specifically including:

[0099] Step S41: Assume that the unmanned surface vessel can perceive obstacles appearing within the map area in real time during navigation, and can accurately obtain the location and size of the obstacles;

[0100] Step S42: Design simulation conditions, store environmental data including wind speed and direction, store trajectory data of each vessel including latitude and longitude, heading angle, speed, communication packet loss rate and energy consumption data, draw simulation condition trajectory diagram, formation member swarm diagram and speed correlation curve, and evaluate the feasibility and flexibility of time-varying formation change control method.

[0101] In a preferred embodiment, the complex environment setup for simulation in step S4 includes a length of 20... Width 6 The narrow waterway has an obstacle radius of 0.5. And its movement speed is 0.5. Moving obstacles and interception levels with a certain width.

[0102] The starting positions of the four unmanned surface vessels (USVs) in the formation are as follows: The central target point of the formation is The initial formation is set to a circle with a radius of [missing information]. ,Towards Direction of navigation, the final trajectory of the formation is as follows Figure 7 As shown, the formation successfully reached the target point, proving the method is feasible.

[0103] The relative positions of the swarm members are shown in the bee swarm diagram. Figure 8 As shown, the distribution of swarm points is striped, indicating that the members' positions within the formation are not fixed and possess a certain degree of flexibility. A speed correlation coefficient was designed, which is the correlation coefficient between the member's speed and the speed of the formation center, to measure the autonomy of the formation members' behavior relative to the formation. The lower the correlation, the more autonomous obstacle avoidance and line-following behaviors are observed; a judgment threshold of 0.8 is set, and a correlation below 0.8 is considered to indicate autonomous behavior by the members; the speed correlation time-history curve is shown below. Figure 9 As shown, members and formation center The average probability of a directional velocity correlation higher than 0.8 is 93.53%, meaning that it occurs. The probability of directional autonomous behavior is 6.47%; The average probability of a directional velocity correlation higher than 0.8 is 85.38%, meaning that it occurs. The probability of directional autonomous behavior is 14.62%. The autonomous behavior of formation members accounts for a certain proportion of the formation's overall behavior, and members possess a certain degree of freedom.

[0104] Therefore, the feasibility and flexibility of the time-varying formation change control method for unmanned surface vessels based on regional control of the present invention were evaluated.

[0105] like Figure 10As shown, this embodiment of the invention provides a time-varying formation transformation control system 100 for unmanned surface vessels based on area control, used to implement the aforementioned time-varying formation transformation control method for unmanned surface vessels based on area control. The system includes the following units:

[0106] Time-varying cooperative mechanism unit 1 is used to constrain the mathematical model of unmanned surface vessels and construct a time-varying cooperative mechanism for unmanned surface vessel formation;

[0107] Tracking and obstacle avoidance planning unit 2 is used to introduce a dynamic window algorithm to build the path tracking and obstacle avoidance capabilities of a single unmanned surface vessel;

[0108] Formation transformation determination unit 3 is used to determine the formation transformation method based on the regional control theory and the quantitative expression of the potential field of the obstacle environment.

[0109] Formation system evaluation unit 4 is used to evaluate the safety and flexibility of the formation system, and to evaluate whether the control method designed for the unmanned surface vessel formation can ensure the safety and flexibility of obstacle avoidance and formation changes.

[0110] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A time-varying formation transformation control method for unmanned surface vessels based on area control, characterized in that, Includes the following steps: Step S1: Constrain the mathematical model of the unmanned surface vessel and construct a time-varying cooperative mechanism for the unmanned surface vessel formation; Step S2: Introduce a dynamic window algorithm to build the path tracking and obstacle avoidance capabilities of a single unmanned surface vessel; Step S3: Based on regional control theory, determine the formation transformation method by formulating a quantitative expression for the potential field according to the obstacle environment; specifically: The objective function for the "mobility domain" is defined as follows: (14) in, , Let be a scalar function with continuous first-order partial derivatives. The number of objective functions; , , This is the location information matrix for the unmanned surface vessel. It is the reference azimuth point of the desired "region". It is a time-varying nonsingular scaling factor, and both are bounded time functions; Based on the artificial potential field method, a collision avoidance potential energy function model of unmanned surface vessels is designed to construct the potential field inside the formation, so as to ensure that the members inside the formation do not collide. The control algorithm is derived to control the unmanned surface vessel to track the moving target "area" so that, under the premise of avoiding collisions with each other, the position and heading angle of the unmanned surface vessel can eventually converge to the desired "movement domain". Step S4: Evaluate the safety and flexibility of the formation system, and assess whether the control method designed for the unmanned surface vessel formation can ensure the safety and flexibility of obstacle avoidance and formation changes.

2. The time-varying formation transformation control method for unmanned surface vessels based on area control as described in claim 1, characterized in that, Step S1 specifically includes: Step S11: Establish the kinematics and dynamics model of the unmanned surface vessel: (1) Wherein, the unmanned surface vessel's position vector is , representing the coordinates and heading angle in the geodetic coordinate system, and the velocity vector. , representing the longitudinal velocity, lateral velocity, and bow angle change rate of the unmanned surface vessel in the body coordinate system; Let be a rotation matrix. The inertial force matrix, The Coriolis force and centripetal force matrix, The damping force matrix is... For power input, The environmental disturbance term is defined as follows: (2) (3) (4) (5) (6) in , , , Reference , representing the hydrodynamic coefficients related to the maneuverability of a surface vessel in each degree of freedom, namely longitudinal, transverse, and bow angle. For the mass of the unmanned surface vessel; for the hydrodynamic coefficients estimated by model tests and empirical formulas, corresponding dimensional conversions are required.

3. The time-varying formation transformation control method for unmanned surface vessels based on area control as described in claim 2, characterized in that, Step S1 further includes: Step S12: Construct the difference set model. Taking a circular formation as an example, define the difference set space for the k-th unmanned surface vessel. That is, the safe zone that the kth unmanned surface vessel can enter within the formation, calculated using the following formula: (7) in, For the Navigator unmanned surface vessel, For the unmanned surface vessels in the formation, excluding the follower A collection of individual unmanned surface vessels outside of the designated areas. This is the set of safe zones containing both stationary and moving obstacles in the environment, where m and n represent the quantities of each. Calculate the difference region space of the formation It should be able to accommodate at least all formation members, that is: (8) in The proportion of individual formation space, i.e., the formation region, is related to the difference space and the capacity of individual formations. This is the proportion of the difference space to the total formation region. When the safe zone space for a single unmanned surface vessel is smaller than that for a single unmanned surface vessel, the formation needs to be changed to accommodate all individuals. The formation change function is as follows: (9) in, , , representing the sudden increase in the turning angle in the heading direction and the abrupt change in the lateral movement direction, respectively; through this function, the constraints of formation transformation with time t, the unmanned surface vessel itself, and the number of individuals in the formation are established. and the area radius of individual unmanned surface vessels The relationship between them.

4. The time-varying formation change control method for unmanned surface vessels based on area control as described in claim 1, characterized in that, Step S2 specifically includes: Define the velocity space of the unmanned surface vessel as Based on the speed performance constraints of unmanned surface vessels Velocity and acceleration coordination constraints The velocity search space is calculated. ;in and Let represent linear acceleration and angular acceleration, respectively. By sampling the velocities that meet the constraints over time, the corresponding trajectory can be obtained. These represent the current velocities in the velocity space; the evaluation function. The sampled trajectories are scored, and the velocity space corresponding to the optimal trajectory is selected as the algorithm's output. The corresponding trajectory is then used as the expected trajectory for the next time step. Direction angle function Used to evaluate the angular error between the predicted trajectory's end heading and the line connecting the trajectory's end to the target point, prompting the unmanned surface vessel to move towards the target; obstacle distance evaluation function. The evaluation function assesses the distance between the predicted trajectory endpoint and the nearest obstacle, penalizing sampling points close to obstacles to reduce the probability of collision and encourage the unmanned surface vessel (USV) to avoid obstacles; a velocity excitation evaluation function is also included. Evaluate the magnitude of the linear velocity at each moment on the predicted trajectory, encourage the unmanned surface vessel to approach the target point at its maximum linear velocity, and encourage the unmanned surface vessel to reach the target quickly; , and Each has its own weight.

5. The time-varying formation change control method for unmanned surface vessels based on area control as described in claim 1, characterized in that, Step S3 specifically includes: Step S31: For the unmanned surface vessel, only consider the three degrees of freedom motion of the unmanned vessel in the horizontal plane: sway, roll, and bow. The desired state vector is given by... , , The desired "mobility domain" must match the corresponding dimension, i.e. If we degenerate it into a circular constraint, the objective functions are defined as follows: in, It is the boundary of the "mobile domain". Coordinate axes within the "expected domain" direction The coordinate values; Coordinate axes within the "expected domain" direction The coordinate values; This represents the heading angle value within the "expected domain," with a subscript of 0 indicating the reference azimuth point. Define time-varying nonsingular scaling factor for: in, for scaling factor, for scaling factor, for The scaling factor means that different scaling factors can be set for position and attitude respectively, achieving decoupled control; when the scaling factor function... When the function value changes over time, the volume of the desired "moving domain" will also change, so the unmanned surface vessel (USV) can track the time-varying "moving domain". This means that the controller can adopt different strategies at different stages, and the USV has a certain degree of path adaptation. but , It can be represented as: The potential function for a single desired "mobility domain" is defined as follows: 。 6. The time-varying formation change control method for unmanned surface vessels based on area control as described in claim 5, characterized in that, Step S3 further includes: Step S32: Set radii of [radii] around the unmanned surface vessel as follows: and The restricted and buffer zones, the current distance between unmanned surface vessels is A collision avoidance potential energy function model was constructed by referencing the design method of artificial potential energy functions, and a piecewise potential field was defined for each unmanned surface vessel accordingly. At this point, all unmanned surface vessels satisfy the "mobile domain". Constrained and unaffected by the regional control potential field. The total collision avoidance potential energy function can be expressed by the following formula: Collision avoidance error It can be written as: 。 7. The time-varying formation transformation control method for unmanned surface vessels based on area control as described in claim 6, characterized in that, Step S3 further includes: Step S33: Based on regional error Collision avoidance error We define the following valid reference vectors. : in, It is a positive constant; Representative vector The reference forward speed, reference lateral speed, and reference turning angular velocity are not the actual measured speeds, but rather the expected speeds calculated from the desired moving domain tracking task, area error, and collision avoidance error, and are used to construct the tracking error. Representation matrix The inverse matrix is ​​defined as in equation 2; For matrix The derivative matrix; For matrix The inverse matrix, based on and The following tracking error vector is defined for the unmanned surface vessel: The unmanned surface vessel (USV) formation change controller is designed as follows: Among them, parameters The update rule is In this rule, For a symmetric positive definite matrix, in Equation 32, For the switching gain control item of the controller, Depend on Derivation, in which And satisfy Combining equations 31 and 32, the closed-loop dynamic control system of the unmanned surface vessel can be obtained as follows: in .

8. The time-varying formation change control method for unmanned surface vessels based on area control as described in claim 1, characterized in that, Step S4 specifically includes: Step S41: Assume that the unmanned surface vessel can perceive obstacles appearing within the map area in real time during navigation, and can accurately obtain the location and size of the obstacles; Step S42: Design simulation conditions, store environmental data including wind speed and direction, store trajectory data of each vessel including latitude and longitude, heading angle, speed, communication packet loss rate and energy consumption data, draw simulation condition trajectory diagram, formation member swarm diagram and speed correlation curve, and evaluate the feasibility and flexibility of time-varying formation change control method.

9. A time-varying formation change control system for unmanned surface vessels based on area control, used to implement the time-varying formation change control method for unmanned surface vessels based on area control as described in any one of claims 1-8, characterized in that, The system includes the following units: The time-varying cooperative mechanism unit is used to constrain the mathematical model of the unmanned surface vessel and construct a time-varying cooperative mechanism for the unmanned surface vessel formation. The tracking and obstacle avoidance planning unit is used to introduce a dynamic window algorithm to build the path tracking and obstacle avoidance capabilities of a single unmanned surface vessel. The formation transformation determination unit is used to determine the formation transformation method based on the regional control theory and the quantitative expression of the potential field in the obstacle environment. The formation system evaluation unit is used to evaluate the safety and flexibility of the formation system, and to assess whether the control method designed for the unmanned surface vessel formation can ensure the safety and flexibility of obstacle avoidance and formation changes.

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