Unmanned surface vehicle path tracking control method and system based on event-triggered switching

Abstract

The application discloses an unmanned ship path tracking control method and system based on event-triggered switching and belongs to the technical field of unmanned ship control. In view of the contradiction between high energy consumption of continuous control and slow response of event-triggered or intermittent control under complex water surface disturbance in the prior art, the application obtains a kinematics and dynamics model, generates a desired speed instruction based on the kinematics model, estimates external total disturbance by using an extended state observer, constructs an inner loop error model according to the difference between the desired speed and the actual speed, and then executes a switching strategy according to the disturbance estimation value by using an event-triggered switching controller. The technical effect of guaranteeing high-precision robust tracking under strong disturbance and significantly reducing control energy consumption under weak disturbance is realized, and the robustness of path tracking is effectively balanced.

Description

Technical Field

[0001] This invention relates to the field of unmanned surface vessel (USV) control technology, and in particular to a path tracking control method and system for USVs based on event-triggered switching. Background Technology

[0002] The statements in this section are merely to provide background information related to the present invention and do not necessarily constitute prior art.

[0003] In complex real-world marine environments, such as when unmanned surface vessels (USVs) perform tasks like shallow-water mapping, near-shore patrols, or port search and rescue, the water surface is often subject to wind, wave, and current interference, uncertain unmodeled dynamics, and variable operating conditions. While traditional proportional-integral-derivative (PI-DI) control and backstepping control methods can achieve basic path tracking, PI-DI has limited resistance to strong nonlinear and time-varying disturbances. Backstepping, on the other hand, suffers from the problem of repeated differentiation in virtual control, which can easily lead to large transient overshoots under strong disturbances and model abrupt changes. Furthermore, to suppress disturbances, its control output is often continuous and high-frequency, resulting in frequent thruster adjustments and high energy consumption. Existing event-triggered control or intermittent control, while reducing the number of control operations, suffers from lag in response to rapidly changing disturbances. In some cases, excessive reduction in control input can weaken the ability to suppress disturbances, easily causing course deviations or even tracking failures. Therefore, in complex water environments with constantly changing wind, waves, and currents, and significant model uncertainties, existing technologies cannot ensure that unmanned surface vessels can maintain fast and robust path tracking in the face of strong external disturbances, while also significantly reducing the control frequency and energy consumption of the propulsion system during weak disturbances or stable navigation. It is difficult to achieve a coordinated balance between high precision and low energy consumption. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an unmanned surface vessel path tracking control method and system based on event-triggered switching. By adaptively switching between continuous control and event-triggered pulse control using disturbance estimates, it achieves high-precision tracking under strong disturbances and low-energy navigation under weak disturbances.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides an unmanned surface vessel path tracking control method based on event-triggered switching, comprising: Obtain the kinematic and dynamic models of unmanned surface vessels; The desired velocity command is generated based on the kinematic model; the total external disturbance in the dynamic model is estimated by an extended state observer to obtain the disturbance estimate. An inner-loop error model is constructed based on the difference between the desired speed command and the actual speed of the unmanned surface vessel. The disturbance estimate and the inner loop error model are processed by an event-triggered switching controller. The event-triggered switching controller executes a switching strategy based on the magnitude of the disturbance estimate: the switching strategy drives the unmanned surface vessel to achieve path tracking.

[0006] Furthermore, a Serret-Frenet coordinate system and a track coordinate system are established, and the kinematic model is transformed to the Serret-Frenet coordinate system; Calculate the positional error between the unmanned surface vessel and the virtual leader point to construct an outer loop error model; Based on the outer loop error model, a guidance law is designed that includes the virtual leader point guidance speed and the desired yaw rate, and the desired speed command is obtained.

[0007] Furthermore, by acquiring the real-time output of the dynamic model through an extended state observer, the sum of the unmodeled dynamics within the system and external disturbances is estimated and reconstructed online to obtain the disturbance estimate.

[0008] Furthermore, the desired velocity command obtained from the guidance law is smoothed by a first-order filter to obtain a smooth desired velocity; Subtracting the expected smooth velocity from the actual velocity yields the forward velocity error and angular velocity error. By combining the dynamic model with the derivative of the error, a set of differential equations describing the dynamic law of the error is derived to construct the inner loop error model.

[0009] Furthermore, the event triggering mechanism in the event triggering switching controller is designed based on Lyapunov functions. The triggering conditions include disturbance estimates as a criterion component, and a preset triggering time interval for the forced pulse is provided to ensure that the system is free from Zeno phenomena.

[0010] Furthermore, the switching strategy is based on a dual-threshold judgment with hysteresis, according to the disturbance estimate and a preset threshold. Based on the comparison results and the current control mode, the system determines whether to output continuous control or event-triggered pulse control.

[0011] Furthermore, the current control mode is event-triggered pulse control, and when the disturbance estimate is greater than or equal to... At this time, the control switches from event-triggered pulse control to continuous control; The current control mode is continuous control, and when the disturbance estimate is less than or equal to... At this time, it switches from continuous control to event-triggered pulse control; In the hysteresis interval The current control mode remains unchanged.

[0012] A second aspect of the present invention provides an unmanned surface vessel path tracking control system based on event-triggered switching, comprising: Model building module: used to obtain the kinematic and dynamic models of unmanned surface vessels; Guidance and Extended State Observation Module: Used to generate the desired velocity command based on the kinematic model; and to estimate the total external disturbance in the dynamic model through the extended state observer to obtain the disturbance estimate. Inner loop error model construction module: used to construct an inner loop error model based on the difference between the desired speed command and the actual speed of the unmanned surface vessel; Event-triggered switching control module: used to process the disturbance estimate and the inner loop error model through the event-triggered switching controller. The event-triggered switching controller executes a switching strategy according to the magnitude of the disturbance estimate: the switching strategy drives the unmanned surface vessel to achieve path tracking.

[0013] In a third aspect, the present invention also provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the method as described in the first aspect.

[0014] In a fourth aspect, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method as described in the first aspect.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention constructs a kinematic and dynamic model, designs an outer-loop guidance law to generate the desired velocity command, and utilizes an extended state observer to estimate the total external disturbance in real time. Furthermore, it constructs an inner-loop error model based on the velocity deviation. Finally, the disturbance estimate and the error model are input together into an event-triggered switching controller, which adaptively executes either continuous control or event-triggered pulse control based on the disturbance magnitude. Under strong disturbances, this invention ensures fast, high-precision path tracking and robustness through continuous control; under weak disturbances, it significantly reduces control frequency and energy consumption through event-triggered pulse control. Simultaneously, by leveraging the disturbance compensation of the extended state observer and the Zeno-free characteristics of the switching control, it achieves high-precision, low-energy, and highly robust path tracking control for unmanned surface vessels in complex water environments. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1 This is a flowchart of the method according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the movement of the unmanned surface vessel according to Embodiment 1 of the present invention; Figure 3 This is a control schematic diagram of an unmanned surface vessel according to Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the outer loop tracking error in the path tracking according to Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the inner loop tracking error in the path tracking of Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the motion trajectory for path tracking according to Embodiment 1 of the present invention. Detailed Implementation

[0018] The following detailed description is exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0020] In this embodiment of the invention, the data collection and processing strictly adhere to the requirements of relevant laws and regulations, obtaining informed consent or separate consent from the data subject, and conducting subsequent data use and processing within the scope of laws, regulations, and the data subject's authorization. All data acquisition in this embodiment is based on compliance with laws and regulations and user consent, representing the lawful application of the data.

[0021] Terminology Explanation: Unmanned Surface Vessels (USVs): USVs are surface robots that do not require personnel to operate them and can complete various tasks on the water using remote commands or autonomous decision-making systems. They typically achieve motion control through a hull, power unit, and steering mechanism, possessing advantages such as strong autonomy, flexible operation, long working hours, and reusability. They are widely used in marine surveying, environmental patrols, disaster relief and rescue, military surveillance, and security patrols. As early as 1898, Nikola Tesla's "remotely controlled automated boat" is considered the earliest prototype of a USV.

[0022] Event triggering mechanism: an inequality judgment criterion containing the system state. When the inequality is true, the pulse action is triggered and the system is subjected to pulse control action.

[0023] Event-triggered control: Event-triggered control is an aperiodic sampling strategy where the controller updates control commands only when the system state deviation exceeds a preset threshold, rather than triggering at fixed time intervals. Its core purpose is to significantly reduce computational load, communication bandwidth, and actuator operation frequency while ensuring system stability and performance, making it particularly suitable for resource-constrained mobile platforms such as unmanned surface vessels.

[0024] Event-triggered pulse control: A pulse control strategy in which the pulse triggering time is determined by an event-triggered mechanism. Its core feature is that the pulse occurrence time depends solely on the event-triggered mechanism. The introduction of the event-triggered mechanism avoids redundant control costs, reduces the number of pulse executions, and thus reduces control energy consumption.

[0025] Event-triggered pulse switching control strategy: This is a switching control strategy based on event-triggered pulse control, consisting of continuous control and event-triggered pulse control. First, the controller switches the control method according to the degree of external water surface disturbance. Specifically, if the external disturbance has a significant impact, continuous control is used to actively compensate for the external influence; if the external disturbance is weak, event-triggered pulse control is used to reduce control costs.

[0026] Extended State Observer (ESO) is a special type of state observer that not only estimates the measurable state of a system, but also treats model uncertainties, unmodeled dynamics, and external disturbances as a "total disturbance," estimating them as an extended state in real time. This enables proactive disturbance rejection control of complex nonlinear systems. For unmanned surface vessels (USVs), ESOs can effectively compensate for unknown hydrodynamic terms and wave disturbances, improving the robustness of path tracking.

[0027] Outer-loop error system: This error system characterizes the deviation between the actual pose of the unmanned surface vessel (USV) and the desired path defined by the virtual guide point. Its state variables typically include lateral deviation, longitudinal deviation, and heading angle deviation. The dynamic evolution of the system is determined by the coupling of the vessel's kinematic model and the motion laws of the virtual guide point. The outer-loop controller drives the error system to converge to a small neighborhood near the origin by outputting the desired velocity command, thereby achieving high-precision path tracking.

[0028] Inner-loop error system: This dynamic system characterizes the deviation between the actual speed of the unmanned surface vessel (USV) (such as forward speed and yaw rate) and the desired speed command given by the outer-loop controller. Its dynamic evolution is mainly governed by the hull dynamics model and includes unknown nonlinear hydrodynamic terms. The design goal of the inner-loop controller is to generate the thrust and torque of the propeller by integrating continuous adaptive control and discrete pulse correction control, thereby suppressing model uncertainties and achieving input-state stability of the speed error system.

[0029] The terms mentioned above are commonly used technical terms in this field, but they have specific meanings in the context of this invention. Those skilled in the art should understand these terms in conjunction with the overall technical solution of this invention. The following embodiments will provide a detailed description of the technical solution of this invention to facilitate its implementation by those skilled in the art.

[0030] Example 1 Compared to existing technologies where pure continuous control suffers from high energy consumption, and pure event-triggered or intermittent control exhibits slow response and weak anti-interference capabilities under complex disturbances, this invention introduces an extended state observer to estimate the total external disturbances, including wind, waves, currents, and unmodeled dynamics, in real time. Using this disturbance estimate as the core basis for the switching criterion, an adaptive switching strategy combining continuous control and event-triggered pulse control is constructed. In actual marine exploration or patrol scenarios, when the unmanned surface vessel encounters sudden strong waves or currents causing the disturbance estimate to exceed a preset threshold, the system automatically switches to continuous control to quickly compensate for the disturbance and ensure trajectory accuracy. When navigating on calm waters with minimal disturbance, the system switches to event-triggered pulse control, applying correction pulses only when necessary, significantly reducing the propeller actuation frequency and control energy consumption. Thus, this invention solves the practical problem of balancing high-precision tracking and low-energy control in complex water environments, achieving a harmonious balance between strong robustness and high economy.

[0031] In a typical embodiment of the present invention, such as Figure 1 As shown, an event-triggered switching-based unmanned surface vessel path tracking control method is disclosed, and the specific steps include: S1: Obtain the kinematic and dynamic models of the unmanned surface vessel; S2: Generate the desired velocity command based on the kinematic model; estimate the total external disturbance in the dynamic model by using an extended state observer to obtain the disturbance estimate; S3: Construct an inner-loop error model based on the difference between the desired speed command and the actual speed of the unmanned surface vessel; S4: The disturbance estimate and the inner loop error model are processed by an event-triggered switching controller. The event-triggered switching controller executes a switching strategy based on the magnitude of the disturbance estimate: the unmanned surface vessel is driven to achieve path tracking through the switching strategy.

[0032] The following describes in detail the above-mentioned unmanned surface vessel path tracking control method based on event-triggered switching, with reference to specific implementation methods.

[0033] In step S1, the kinematic and dynamic models of the unmanned surface vessel are obtained, including: establishing an inertial coordinate system and a body coordinate system, obtaining the kinematic equations describing the pose changes based on the coordinate transformation relationship, and obtaining the dynamic equations describing the velocity changes based on hydrodynamics and underactuated characteristics.

[0034] As one implementation method, based on the underactuated characteristics of unmanned surface vessels, a kinematic model and a dynamic model are established. The specific steps are as follows: Based on the motion environment of the unmanned surface vessel (USV), an inertial coordinate system and a body coordinate system are established to obtain the USV's position and velocity information in the inertial coordinate system. In this embodiment, the position information is referred to as position coordinates. Based on the fundamental laws of kinematics of unmanned surface vessels (USVs) and the transformation relationship between the inertial coordinate system and the body coordinate system, a kinematic model of the USV is established. Based on hydrodynamics, the underactuated characteristics of unmanned surface vessels (USVs), and the differential propulsion principle of USVs, a dynamic model of the USV is established.

[0035] by Figure 2 Taking the illustrated diagram of the movement of the unmanned surface vessel as an example, the specific process is as follows: First, based on reasonable assumptions about the physical environment of the unmanned surface vessel, an inertial coordinate system is established. ,in Represents the origin of the inertial coordinate system. Representing the inertial coordinate system axis, Representing the inertial coordinate system Axis. Establish the body coordinate system based on the current state of the unmanned surface vessel. ,in, This represents the origin of the body coordinate system, i.e., the center of mass of the unmanned surface vessel. Representing the body coordinate system axis, Representing the body coordinate system axis.

[0036] Based on the transformation relationship between the inertial coordinate system and the body coordinate system, the kinematic model of the unmanned surface vessel can be obtained in the inertial coordinate system:

[0037] in, This represents the coordinates of the unmanned surface vessel in the inertial coordinate system. Indicates the yaw angle of an unmanned surface vessel. These represent the forward speed, sway speed, and yaw rate of the unmanned surface vessel in the body coordinate system, respectively.

[0038] Unmanned surface vessels (USVs) typically exhibit underactuated characteristics, meaning they lack direct control input for yaw velocity. Therefore, considering only the forward velocity and yaw rate as control inputs, and taking into account the complex water environment, we can derive the dynamic model of the USV:

[0039] in, This refers to the total mass, including the mass of the unmanned surface vessel and the hydrodynamic added mass. This represents the corresponding hydrodynamic damping coefficient. These represent the control inputs for forward speed and yaw rate, respectively.

[0040] In S2, the desired path is transformed into the longitudinal and angular velocity targets required by the hull through the guidance law; the extended state observer estimates and reconstructs the sum of unmodeled dynamics within the system and external disturbances such as wind, waves and currents in the environment online based on the real-time output of the dynamic model, thereby obtaining the disturbance estimate.

[0041] S201: Based on the kinematic model of the unmanned surface vessel (USV), the desired path trajectory, and the USV's position information, establish the outer loop error system and design the guidance law. The specific steps are as follows: 1) Establish the Serret-Frenet (SF) coordinate system and the track coordinate system based on the given path; 2) Based on the curvature characteristics of the given desired trajectory, the kinematic model of the unmanned surface vessel, and the current position of the unmanned surface vessel, transform the kinematic model of the unmanned surface vessel in the inertial coordinate system to the Serret-Frenet coordinate system. 3) Calculate the positional errors of the unmanned surface vessel and the virtual leader point in the Serret-Frenet coordinate system, and establish the outer loop error system (outer loop error model). 4) Based on the outer loop error system, design the desired yaw rate and the guiding speed of the virtual leader point.

[0042] by Figure 2 Taking the illustrated diagram of the movement of the unmanned surface vessel as an example, the specific process is as follows: First, establish the Serret-Frenet coordinate system based on the desired path information. ,in This represents the origin of the Serret-Frenet coordinate system. Representing the Serret-Frenet coordinate system axis, Representing the Serret-Frenet coordinate system Axis. Establish a trajectory coordinate system based on the current motion state of the unmanned surface vessel. ,in This represents the origin of the trajectory coordinate system, i.e., the center of mass of the unmanned surface vessel. Represents the coordinate system of the track. axis, Represents the coordinate system of the track. axis.

[0043] remember Let these be the coordinates of the virtual leadership point in the inertial coordinate system. The yaw angle representing the virtual leader point can be used to establish the error in the inertial coordinate system. Assuming the drift angle is Then the yaw angle error can be expressed as Therefore, the rotation matrix for coordinate system transformation can be expressed as:

[0044] Therefore, the kinematics of the unmanned surface vessel in the inertial coordinate system can be expressed in the Serret-Frenet coordinate system as follows:

[0045] in, This represents the velocity in the track coordinate system. This represents the position error vector between the unmanned surface vessel and the virtual leader point in the Serret-Frenet coordinate system. Let represent the yaw rate of the virtual leader point. Expanding this equation yields the following outer-loop error system:

[0046] According to the outer loop error system, its form containing the expected value can be written as:

[0047] Therefore, the guidance law can be designed as follows:

[0048] in, This indicates the guidance speed of the virtual leadership point. Indicates the desired yaw rate. These are control parameters. The definition is as follows:

[0049] in, These are control parameters.

[0050] S202: By acquiring the real-time output of the dynamic model through the extended state observer, the system's internal unmodeled dynamics and the sum of external disturbances such as wind, waves and currents are estimated and reconstructed online, thereby obtaining the disturbance estimate.

[0051] Among them, unmodeled dynamics within the system refer to nonlinear hydrodynamic terms that are difficult to obtain accurately in the dynamic model of the unmanned surface vessel, model simplification errors, and parameter uncertainties (such as changes in added mass and damping coefficients). External disturbances such as wind, waves, and currents refer to the time-varying external forces and moments generated on the hull by unknown wind, waves, ocean currents, etc. in complex water environments.

[0052] The specific steps for designing an extended state observer are as follows: An extended state observer system is established based on the output feedback of the actual observations; a state observation error system is constructed, and the feedback gain of the actual observations is analyzed and designed.

[0053] As one implementation method, the specific process is as follows: For the dynamic model of the unmanned surface vessel, the following vector form equations can be written:

[0054] in, Indicates the output. Indicates discontinuous control input. This represents the actual observed value indicating the status of unmanned surface vessels. This represents the true value of the total disturbance experienced by the unmanned surface vessel. Based on the output feedback of the true observation values, the following extended state observer system can be established:

[0055] in, Indicates the output feedback gain. Observations representing the status of unmanned surface vessels. This represents an estimate of the total disturbance experienced by the unmanned surface vessel.

[0056] In S3, an inner-loop error model is established to characterize the dynamic characteristics of speed tracking deviation based on the difference between the desired speed command and the actual speed of the unmanned surface vessel.

[0057] In this embodiment, the inner-loop error model refers to the inner-loop error system, which is a mathematical model used to describe the dynamic characteristics of the deviation between the actual speed and the desired speed command of an unmanned surface vessel. The process of establishing the inner-loop error system is the process of constructing this mathematical model.

[0058] The specific steps for establishing the inner-loop error system and designing the inner-loop controller and switching criteria are as follows: First, the virtual leader point guidance speed (as the desired forward speed) and desired yaw rate output by the guidance law are used as the original desired speed command. They are then smoothed by a first-order filter to obtain a smooth desired speed command, thus avoiding sudden changes that could impact the control system. Simultaneously, the current actual speed of the unmanned surface vessel (the actual speed includes the actual forward speed and the actual angular velocity) is collected. Specifically, the actual forward speed (linear velocity along the longitudinal direction of the hull) and the actual angular velocity (yaw angular velocity around the vertical axis) of the unmanned surface vessel are collected in real time through onboard sensors (such as GPS, inertial measurement unit and attitude sensor) to obtain the actual speed vector characterizing the instantaneous motion state of the hull. Then, the filtered smoothed expected velocity is subtracted from the actual velocity to obtain the forward velocity error and angular velocity error. These errors (forward velocity error and angular velocity error) are differentiated by combining the dynamic equations (i.e., dynamic model) of the unmanned surface vessel, and a set of differential equations describing the dynamic change of the error is derived. This set of equations is the inner loop error model, thus establishing an inner loop error model describing the dynamic evolution of the speed tracking deviation. Based on this, continuous control input and event-triggered pulse control input are designed according to the total disturbance estimated by the inner loop error model and the extended state observer, respectively. Finally, a switching criterion is designed based on the disturbance estimate output by the extended state observer, enabling the system to adaptively switch between continuous control and event-triggered pulse control to complete the path tracking control of the unmanned surface vessel.

[0059] As one implementation method, the specific process is as follows: Based on the desired angular velocity and desired forward velocity obtained from the guidance law, a first-order filter is established to smooth the desired signal. The specific form of the filter is as follows:

[0060] in, It is the desired signal output by the guidance law. It is the smoothed desired signal after the filter output, which can be obtained by subtracting it from the current state information of the unmanned surface vessel. Therefore, the inner-loop error system of the unmanned surface vessel can be written as:

[0061] in, These are the equivalent mass of the unmanned surface vessel in the direction of travel and the equivalent moment of inertia during rotation. The inner loop control input is shown in the table below. They represent Subsystem and Subsystem switching signals, These represent external disturbances in the forward direction and external disturbances in the rotation, respectively; nonlinear functions. They are represented as follows:

[0062] in, This represents the equivalent mass of the unmanned surface vessel in the sway direction. These represent the water surface damping in the oscillation direction and the rotation process, respectively.

[0063] The disturbance estimate output by the extended state observer and the inner loop error model are input together into the event-triggered switching controller. The controller compares the disturbance estimate with a preset threshold in real time: if the disturbance estimate is greater than or equal to the threshold, it indicates that the external disturbance is significant, and continuous control is output to actively compensate for the disturbance and suppress the deviation; conversely, if the disturbance estimate is less than the threshold, it indicates that the disturbance is weak, and event-triggered pulse control is output to reduce the control frequency and energy consumption. The resultant force and torque generated by the above switching strategy drive the unmanned surface vessel to correct the speed deviation in real time, realizing high-precision path tracking in complex disturbance environments.

[0064] As one implementation method, based on the inner-loop error system and the extended state observer, the continuous control input and the event-triggered pulse control input can be designed separately. First, the continuous control input can be written as:

[0065] in, Indicates control gain. It is the extended state observer at the forward speed The total disturbance for direction estimation. Furthermore, the event-triggered pulse control input can be written as:

[0066] in, Represents the Dirac impulse function. Indicates pulse gain. Indicates forward speed The pulse timing sequence during control.

[0067] The event triggering mechanism in the event-triggered switching controller is designed based on the Lyapunov function. The triggering condition includes the disturbance estimate as a criterion component, and a maximum triggering time interval for the forced pulse is set to ensure that the system is free from Zeno phenomenon. For example, in the given simulation test, the maximum interval of the forced pulse is selected as 3 seconds.

[0068] The event-triggered switching controller's event-triggered mechanism is based on Lyapunov function design. It constructs a trigger inequality containing the system error state and disturbance estimate as a criterion. Pulse control is only generated when the inequality is true or when a preset forced trigger time interval is reached. The introduction of disturbance estimate enables the trigger condition to respond to changes in the external environment in real time, avoiding redundant control. The forced trigger time interval ensures, from an engineering perspective, that the minimum time interval between two adjacent pulses is always positive. Thus, theoretically and practically, it eliminates the Zeno phenomenon that occurs with an infinite number of pulses within a finite time, ensuring the feasibility and stability of the system.

[0069] Event-triggered pulse control depends on the design of the event-triggered mechanism. Based on the estimated magnitude of the total external disturbance, the event-triggered mechanism can be written as:

[0070] in, This indicates the trigger time interval of the forced pulse, for example, selected in simulation testing. , Indicates the parameters of the event triggering mechanism. The Lyapunov function represents the upper bound of the total external disturbance. .

[0071] In this embodiment, a hysteresis interval is added, and its half-width can be selected according to the project, for example, 0.1 to 0.5.

[0072] The switching strategy is based on a hysteresis-enabled dual-threshold judgment, which compares the disturbance estimate with a preset threshold. Based on the comparison results and the current control mode, the system determines whether to output continuous control or event-triggered pulse control: the current control mode is event-triggered pulse control, and the disturbance estimate is greater than or equal to... When the event-triggered pulse control switches to continuous control, the current control mode is continuous control, and the disturbance estimate is less than or equal to... At that time, it switches from continuous control to event-triggered pulse control; in the hysteresis interval The current control mode remains unchanged.

[0073] As one implementation, the total magnitude of the external disturbance can be described based on the estimate of the external disturbance by the extended state observer. To fully utilize the disturbance information, the switching criterion can be designed as follows:

[0074] Among them, subscript Indicating targeting Subsystem switching criteria It is half the width of the hysteresis interval. This represents the estimated ESO disturbance value. Is the switch in The state before a given time, and the switching strategy with a hysteresis interval, can avoid frequent switching. When A value of 2 indicates a continuous control strategy, while a value of 1 indicates event-triggered pulse control. A similar switching criterion for angular velocity control can be designed. Under the guidance law and the event-triggered pulse switching control strategy, the unmanned surface vessel can achieve path tracking within the input-state stability framework if the following conditions are met:

[0075] The path tracking of the unmanned surface vessel (USV) is achieved by switching criteria. The specific process is as follows: the event-triggered switching controller selects either continuous control mode or event-triggered pulse control mode in real time based on the comparison between the current disturbance estimate and the preset threshold, and outputs corresponding control commands (thrust and torque). These control commands are applied to the dynamic system of the USV, directly adjusting the forward speed and yaw rate of the hull, so that the actual speed continuously tracks the desired speed command. At the same time, the outer-loop guidance law continuously updates the desired speed command based on the attitude deviation, while the inner-loop controller eliminates speed tracking deviation through the above switching strategy. Under the synergistic effect of the inner and outer loops, the actual navigation trajectory of the USV is continuously corrected and converged to a small neighborhood near the desired path, thereby achieving stable and high-precision path tracking in complex water surface disturbance environments.

[0076] Event-triggered pulse control is applied only when either of the following conditions is met: the disturbance estimate rises to... Above (switching from event-triggered pulse mode to continuous mode), the disturbance estimate decreases to The following occurs (switching from continuous mode back to event-triggered pulse mode), or the preset maximum trigger time interval is reached, for example, the maximum trigger interval selected in the simulation test is 3 seconds.

[0077] The following proves this conclusion, which consists of two parts.

[0078] Part One: First, the error system does not exhibit the Zeno phenomenon under an event-triggered mechanism. If the pulse sequence is entirely composed of forced pulse sequences, then there is naturally a lower bound on the interval. If the pulse sequence is a pulse sequence caused entirely by event triggers, then any interval... Differentiating the inner Lyapunov function with respect to it, we get:

[0079] According to the event triggering mechanism, there is a lower bound between the triggering times:

[0080] Therefore, the Zeno phenomenon does not exist under this event triggering mechanism.

[0081] Part Two: The input-state stability of the error system is then proven by taking the following Lyapunov function:

[0082] Differentiating the Lyapunov function over a continuous control interval yields:

[0083] make Integrating over this interval yields:

[0084] Similarly, within the event-triggered pulse control range, based on the event-triggered mechanism, we can obtain:

[0085] Therefore, we can conclude through induction that:

[0086] By discussing the relationship between the continuous control interval and the event-triggered pulse control interval separately, it can be proven that their existence... Class function and Class function This makes the following estimate true:

[0087] Therefore, the error system corresponding to the forward velocity is input-state stable. Similarly, the angular velocity error system can be estimated in a similar way, and thus it is also input-state stable. Clearly, the outer-loop error system is input-state stable. Therefore, based on the input-state stability properties of cascaded systems, it can be proven that the cascaded system of the inner and outer loops is also input-state stable. Therefore, within the input-state stability framework, unmanned surface vessels can achieve path tracking.

[0088] This invention also provides corresponding electronic devices and a configuration environment. The electronic devices include a heterogeneous architecture of a Raspberry Pi 4B (host computer) and a Pixhawk 2.4.8 flight controller (lower-level controller). The system deploys a ROS (Robot Operating System) environment as the core middleware, and through deep configuration, it can achieve the following: Event-triggered pulse switching control strategy for unmanned surface vessel path tracking under complex water surface disturbance environment: The event-triggered pulse switching control strategy program for unmanned surface vessel path tracking under complex water surface disturbance environment is natively run in the ROS layer to accurately execute the path tracking task of the unmanned surface vessel.

[0089] Cross-platform communication: Enables efficient command / data interaction between Raspberry Pi (decision layer) and Pixhawk (execution layer) through the MAVROS bridging module.

[0090] The following is based on the target trajectory Initial coordinates of the unmanned surface vessel Taking an example, the effectiveness of the pulse-corrected path tracking control method for unmanned surface vessels described in this example is further illustrated. Table 1 shows the inner and outer loop error data under the pulse-corrected path tracking control method for unmanned surface vessels. It can be seen that both the inner and outer loop errors of the system converge to bounded quantities. The above results indicate that the pulse-corrected control method disclosed in this paper can effectively achieve path tracking of unmanned surface vessels.

[0091] Table 1. Inner and outer loop system errors of unmanned surface vessels under the method and strategy proposed in this invention.

[0092] also, Figure 3 This is a schematic diagram of the control system for the unmanned surface vessel (USV) of the present invention. The system first generates a path tracking command based on the deviation between the given path and the USV's actual pose, using a guidance law and filtering. Simultaneously, for unknown external disturbances, the system uses an extended state observer to perform real-time estimation and transmits the estimated value to the controller. At the control layer, the core switching law integrates the filtered command, the USV's own velocity feedback, and the switching law to determine which control strategy to use at the current moment: either a conventional continuous control law or an event-triggered pulse control law that incorporates disturbance estimation for active compensation. Finally, the controller outputs control torque to drive the USV, forming a closed-loop control system with anti-interference capabilities and optimized efficiency.

[0093] Figure 4 This is a schematic diagram of the outer loop tracking error for path tracking according to the present invention; as shown. Figure 4 As shown, assuming the unmanned surface vessel is initially stationary at the origin of the world coordinate system, the desired tracking trajectory is from the initial position (20, 0, ...). The virtual leader point is generated with a curvature of 0.05. This image illustrates the evolution of the outer loop tracking error under the above initial values.

[0094] Figure 5 This is a schematic diagram of the inner loop tracking error of the path tracking according to the present invention; the diagram shows the evolution of the inner loop tracking error within 120 seconds under the above initial value in the unmanned surface vessel path tracking control method based on event-triggered switching.

[0095] Figure 6This is a schematic diagram of the motion trajectory for path tracking according to the present invention; the diagram illustrates the relationship between the simulated motion trajectory of the unmanned surface vessel and the desired trajectory of the virtual leader point under the aforementioned initial values. This image demonstrates that the trajectory tracking task can be effectively completed using the control method proposed in this invention.

[0096] As can be seen, this invention establishes an inner and outer loop cascaded error model based on the kinematic and dynamic characteristics of the unmanned surface vessel (USV), and designs a hybrid switching strategy that integrates continuous control and event-triggered pulse control, achieving high-precision path tracking with low control costs. Compared with traditional control methods, this invention fully considers the beneficial effects of external disturbances, and adaptively selects the control mode through a switching law. When the disturbance is conducive to tracking, it automatically switches to the event-triggered pulse control mode, significantly reducing control energy consumption and improving the adaptability to complex water surface environments.

[0097] This invention, based on an input-state stability framework, proves the input-state stability of the outer-loop error system, the inner-loop error system, and the filter system using the outer-loop guidance law and the inner-loop switching control law, respectively. Noting that these subsystems collectively constitute a cascaded structure, the global input-state stability of the entire closed-loop system is guaranteed according to the cascaded system input-state stability theory, providing a stringent stability guarantee for path tracking control.

[0098] This invention employs an extended state observer for real-time estimation and compensation of unknown disturbances in complex water environments. Compared to traditional methods, this invention only requires adjusting the observer bandwidth parameter to ensure the input-state characteristics of the estimation error. Theoretical analysis and numerical simulations show that the proposed method maintains high-precision tracking even in the presence of external disturbances, with both lateral and longitudinal tracking errors converging to a small neighborhood of the origin.

[0099] The event-triggered pulse switching control strategy proposed in this invention employs an event-triggered mechanism based on Lyapunov functions. Event-triggered pulse control is applied only when the disturbance estimate exceeds the hysteresis interval threshold or reaches the maximum interval time, thus avoiding frequent updates in continuous control. Compared to traditional event-triggered control based on a zero-order hold, this method fundamentally eliminates chattering in the control input and rigorously proves the absence of Zeno behavior. Numerical simulation results show that, compared to a purely continuous control strategy, the proposed method significantly reduces control costs while maintaining considerable path tracking accuracy and optimizing energy consumption.

[0100] The event-triggered pulse-based switching control method proposed in this invention performs excellently in path tracking tasks for unmanned surface vehicles (USVs), and its design framework has good scalability. In other scenarios, such as multiple USVs, the system can still maintain stable control performance when facing typical engineering problems such as model uncertainty, external wave interference, and actuator physical constraints, demonstrating strong engineering applicability and promotional value.

[0101] Example 2 In a typical embodiment of the present invention, an unmanned surface vessel path tracking control system based on event-triggered switching is provided, comprising: Model building module: used to obtain the kinematic and dynamic models of unmanned surface vessels; Guidance and Extended State Observation Module: Used to generate the desired velocity command based on the kinematic model; and to estimate the total external disturbance in the dynamic model through the extended state observer to obtain the disturbance estimate. Inner loop error model construction module: used to construct an inner loop error model based on the difference between the desired speed command and the actual speed of the unmanned surface vessel; Event-triggered switching control module: used to process the disturbance estimate and the inner loop error model through the event-triggered switching controller. The event-triggered switching controller executes a switching strategy according to the magnitude of the disturbance estimate: the switching strategy drives the unmanned surface vessel to achieve path tracking.

[0102] Example 3 The purpose of this embodiment is to provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the method of Embodiment 1.

[0103] Example 4 The purpose of this embodiment is to provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method of Embodiment 1.

[0104] The steps and methods involved in Embodiments 3 and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0105] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0107] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. An unmanned surface vessel path tracking control method based on event-triggered switching, characterized in that, include: Obtain the kinematic and dynamic models of unmanned surface vessels; Generate the desired velocity command based on the kinematic model; The total external disturbance in the dynamic model is estimated by using an extended state observer to obtain the disturbance estimate. An inner-loop error model is constructed based on the difference between the desired speed command and the actual speed of the unmanned surface vessel. The disturbance estimate and the inner loop error model are processed by an event-triggered switching controller. The event-triggered switching controller executes a switching strategy based on the magnitude of the disturbance estimate. The switching strategy drives the unmanned surface vessel to achieve path tracking. Specifically, the event-triggered switching controller selects either continuous control mode or event-triggered pulse control mode in real time based on the comparison result between the current disturbance estimate and a preset threshold, and outputs corresponding control commands. These control commands are applied to the dynamics system of the unmanned surface vessel, directly adjusting the forward speed and yaw rate of the hull. At the same time, the outer loop guidance law continuously updates the desired speed command based on the attitude deviation, while the inner loop controller eliminates speed tracking deviation through the aforementioned switching strategy. Under the synergistic effect of the inner and outer loops, the actual navigation trajectory of the unmanned surface vessel is continuously corrected and converged to a small neighborhood near the desired path. The switching strategy is based on a hysteresis-based dual-threshold judgment, which determines the switching based on the disturbance estimate and a preset threshold. Based on the comparison results and the current control mode, determine whether to output continuous control or event-triggered pulse control; The current control mode is event-triggered pulse control, and it is used when the disturbance estimate is greater than or equal to... At this time, the control switches from event-triggered pulse control to continuous control; The current control mode is continuous control, and when the disturbance estimate is less than or equal to... At this time, it switches from continuous control to event-triggered pulse control; In the hysteresis interval The current control mode remains unchanged.

2. The unmanned surface vessel path tracking control method based on event-triggered switching as described in claim 1, characterized in that, Establish the Serret-Frenet coordinate system and the track coordinate system, and transform the kinematic model to the Serret-Frenet coordinate system; Calculate the positional error between the unmanned surface vessel and the virtual leader point to construct an outer loop error model; Based on the outer loop error model, a guidance law is designed that includes the virtual leader point guidance speed and the desired yaw rate, and the desired speed command is obtained.

3. The unmanned surface vessel path tracking control method based on event-triggered switching as described in claim 1, characterized in that, By acquiring the real-time output of the dynamic model through an extended state observer, the sum of the unmodeled dynamics inside the system and external disturbances is estimated and reconstructed online, thus obtaining the disturbance estimate.

4. The unmanned surface vessel path tracking control method based on event-triggered switching as described in claim 1, characterized in that, The desired velocity command obtained from the guidance law is smoothed by a first-order filter to obtain a smooth desired velocity. Subtracting the expected smooth velocity from the actual velocity yields the forward velocity error and angular velocity error. By combining the dynamic model with the derivative of the error, a set of differential equations describing the dynamic law of the error is derived to construct the inner loop error model.

5. The unmanned surface vessel path tracking control method based on event-triggered switching as described in claim 1, characterized in that, The event triggering mechanism in the event triggering switching controller is designed based on Lyapunov functions. The triggering conditions include disturbance estimates as a criterion component, and a preset triggering time interval for the forced pulse is provided to ensure that the system is free from Zeno phenomena.

6. An unmanned surface vessel path tracking control system based on event-triggered switching, characterized in that, include: Model building module: used to obtain the kinematic and dynamic models of unmanned surface vessels; Guidance and extended state observation module: used to generate the desired velocity command based on the kinematic model; The total external disturbance in the dynamic model is estimated by using an extended state observer to obtain the disturbance estimate. Inner loop error model construction module: used to construct an inner loop error model based on the difference between the desired speed command and the actual speed of the unmanned surface vessel; Event-triggered switching control module: used to process the disturbance estimate and the inner loop error model through the event-triggered switching controller. The event-triggered switching controller executes a switching strategy according to the magnitude of the disturbance estimate. The switching strategy drives the unmanned surface vessel to achieve path tracking. The specific process is as follows: the event-triggered switching controller selects the continuous control mode or the event-triggered pulse control mode in real time according to the comparison result between the current disturbance estimate and the preset threshold, and outputs the corresponding control command. These control commands are applied to the dynamics system of the unmanned surface vessel, directly adjusting the forward speed and yaw rate of the hull. At the same time, the outer loop guidance law continuously updates the desired speed command based on the attitude deviation, while the inner loop controller eliminates speed tracking deviation through the aforementioned switching strategy. Under the synergistic effect of the inner and outer loops, the actual navigation trajectory of the unmanned surface vessel is continuously corrected and converged to a small neighborhood near the desired path. The switching strategy is based on a hysteresis-based dual-threshold judgment, which determines the switching based on the disturbance estimate and a preset threshold. Based on the comparison results and the current control mode, determine whether to output continuous control or event-triggered pulse control; The current control mode is event-triggered pulse control, and it is used when the disturbance estimate is greater than or equal to... At this time, the control switches from event-triggered pulse control to continuous control; The current control mode is continuous control, and when the disturbance estimate is less than or equal to... At this time, it switches from continuous control to event-triggered pulse control; In the hysteresis interval The current control mode remains unchanged.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-5.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method as described in any one of claims 1-5.

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