Unmanned ship path tracking method and system based on improved LOS algorithm and adaptive PID control

Abstract

The application discloses an unmanned ship path tracking method based on an improved LOS algorithm and adaptive PID control in the technical field of unmanned ship control, which comprises the following steps: step 1) planning a desired path according to specific task requirements; step 2) adopting the improved LOS guidance algorithm to track the path, compensating for the desired heading angle in the straight line tracking stage; in the turning tracking stage, the variable speed and variable radius tangent circle parameter method are adopted to realize smooth transition of turning; step 3) obtaining the actual heading of the unmanned ship according to the inertial navigation and other measuring devices carried by the unmanned ship, comparing the actual heading with the desired heading of the set path to obtain a difference value, and adopting the adaptive PID control method to generate a control signal; step 4) after receiving the control signal generated by the control layer, driving the actuator in the system to make corresponding changes, so that the unmanned ship sails according to the desired heading, and finally realizes path tracking; the application improves the accuracy of path tracking by improving the traditional LOS guidance algorithm.

Description

Technical Field

[0001] This invention relates to the field of unmanned vessel control technology, and in particular to a method for unmanned vessel path tracking. Background Technology

[0002] With the advancement of technology and the development of intelligent systems, unmanned operations are becoming increasingly widespread, and the application of unmanned vehicles, drones, unmanned boats, and other unmanned equipment has been greatly promoted. Unmanned boats, as a type of unmanned surface equipment, have advantages such as small size, low cost, high maneuverability, and the ability to adapt to various complex water environments. By carrying different equipment, they can perform tasks such as water quality monitoring, climate observation, ocean exploration, surface search and rescue, and fire support, showing broad application prospects in military, scientific research, and industrial fields.

[0003] Currently, unmanned surface vessels (USVs) are generally used to reach designated locations and complete specific tasks by following a specific route. Therefore, in practical applications, in order to complete tasks more accurately and efficiently, while considering the underactuated nature of USVs and the impact of the aquatic environment on their maneuverability, the requirements for USVs' ability to track according to preset routes are becoming increasingly stringent.

[0004] In unmanned surface vessel (USV) path tracking strategies, the ultimate goal is to guide the USV along a pre-defined target point and path with minimal deviation. Existing path tracking methods often employ a split control scheme, dividing the control into outer-loop guidance and inner-loop control. Outer-loop guidance, or track control, typically uses the LOS (Longest-of-Sight) guidance algorithm. Traditional LOS guidance algorithms use a fixed forward-looking distance (Δ) set empirically, generally N (1.5-5) times the ship's length. When the USV's speed is high or the turning angle is obtuse, the system exhibits overshoot; however, it generally meets tracking requirements when the USV's speed is low or the turning angle is acute. Inner-loop control, or heading control, commonly employs methods such as PID control, fuzzy control, sliding mode control, and backstepping. Traditional PID control performs well under relatively small external disturbances, but its effectiveness diminishes under highly variable external disturbances. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an unmanned surface vessel (USV) path tracking method based on an improved LOS algorithm and adaptive PID control. Considering the impact of USV speed and turning angle on path tracking control, the method improves the traditional LOS guidance algorithm to enhance path tracking accuracy. Furthermore, taking into account the disturbances caused by the aquatic environment to USV control, an adaptive PID controller is designed to improve heading control accuracy.

[0006] The objective of this invention is achieved as follows: a path tracking method for unmanned surface vessels based on an improved LOS algorithm and adaptive PID control, comprising the following steps:

[0007] Step 1) Based on the specific task requirements, plan the desired path;

[0008] Step 2) In outer-loop guidance, an improved LOS guidance algorithm is used for path tracking. The desired heading angle is compensated during the straight-line tracking phase. During the turning tracking phase, a method using variable speed and variable radius tangent circle parameters is used to achieve a smooth turning transition.

[0009] Step 3) In the inner loop control, the actual heading of the unmanned vessel is obtained from the inertial navigation and other measurement equipment on board the unmanned vessel. The difference is compared with the expected heading of the set path, and the control signal is generated by the adaptive PID control method.

[0010] Step 4) In the execution layer, after receiving the control signal generated by the control layer, the actuators in the drive system make corresponding changes to enable the unmanned vessel to sail in the desired course, ultimately achieving path tracking.

[0011] Furthermore, in step 2), the method for compensating for the desired heading angle during the straight-line tracking phase includes:

[0012] 2-1) The designed variable forward sight distance is set to a value that is large when the lateral deviation is greater than the radius of the forward sight circle. As the unmanned vessel approaches the desired path, the lateral deviation decreases. At this point, it is desirable to increase the forward look-ahead distance to achieve smoother path tracking. The variable forward look-ahead distance must meet the following conditions:

[0013]

[0014] In the formula, For minimum forward sight distance, To maximize the forward sight distance, A constant that is greater than zero. The lateral deviation of the unmanned vessel from the desired path;

[0015] 2-2) Calculate the final expected heading angle of the unmanned vessel. :

[0016]

[0017]

[0018]

[0019]

[0020] in, The deviation angle for heading tracking. To calculate the expected heading angle of the unmanned vessel, This is the actual heading angle of the unmanned vessel. For the heading angle that needs to be compensated, This represents the maximum steering angle of the unmanned vessel during navigation. This is the compensation coefficient for the deviation angle.

[0021] Furthermore, in step 2), the turning tracking phase employs a method using variable speed and variable radius tangent point parameters to achieve a smooth turning transition, specifically including:

[0022] 2-3) When the speed is high and the turning angle is greater than 90°, the large turning angle is decomposed into three smaller turning angles, and path tracking is performed on the route. , Tracking is converted into route tracking , , , Tracking enables smooth transitions during turns:

[0023] 2-4) When the speed is low and the turning angle is less than 90°, the forward sight radius will be adjusted according to the actual speed of the current tracking path. The higher the speed, the greater the increase in forward sight distance; conversely, the lower the speed, the smaller the increase in forward sight distance. The variable forward sight radius satisfies the following conditions:

[0024]

[0025] In the formula, For minimum forward sight distance, To maximize the forward sight distance, The current actual speed, This is the maximum speed of the unmanned vessel.

[0026] Furthermore, in 2-3), the larger turning angle is decomposed into three smaller turning angles, specifically as follows:

[0027] point , , Let each point be an adjacent point on a desired path. , , Let point be one of the three virtual turning points at point , where point is the most important. , The circle and line segment are respectively the point of tangency with variable radius. , The intersection (tangent point) of the points for The intersection of the angle bisector and the circle of tangency with a variable radius;

[0028] in , The coordinates of a point satisfy the following conditions:

[0029]

[0030]

[0031] At this point, the coordinates of the center of the circle at the point of tangency with a variable radius The following conditions must be met:

[0032]

[0033] but The coordinates of a point satisfy the following conditions:

[0034] .

[0035] Furthermore, in step 3), an adaptive PID control method is used in the inner loop control to generate control signals to achieve motion control of the unmanned vessel, and a speed controller and a heading controller are designed respectively.

[0036] The PID calculation formula for adaptive speed control is as follows:

[0037]

[0038] In the formula, The proportional gain of the PID controller; The integral coefficient of the PID controller. This is the integral error; The derivative coefficients of the PID controller are... This is the differential error; This represents the difference between the current actual speed and the target speed. This is the speed difference calculated at the previous moment. The speed value output by the speed control.

[0039] The PID calculation formula for adaptive heading control is as follows:

[0040]

[0041] In the formula, The proportional gain of the PID controller; The integral coefficient of the PID controller. The range of values ​​is , This is the integral error; The derivative coefficients of the PID controller are... The range of values ​​is , This is the differential error; This is the difference between the current heading and the target heading. This is the heading difference calculated at the previous moment. The heading value output by the heading control.

[0042] Furthermore, the specific operational steps in the execution layer of step 4) are as follows:

[0043] 4-1) Construct a heading PID controller and a speed PID controller respectively, set the safe range of the rudder angle and the threshold of the heading angle, and set the safe range and threshold of the main engine speed and RPM respectively; the safe range of the rudder angle is -30° to +30°, and the threshold range of the heading angle is 0.5° to 1°; the safe range of the main engine RPM is set according to the main engine's technical instructions, and the threshold is set to 0.05 to 0.1 times the maximum RPM;

[0044] 4-2) The actual heading of the unmanned surface vessel (USV) is obtained by the measuring equipment on board. The desired heading of the USV is obtained by sending commands from the telemetry and control terminal. The difference between the actual heading and the desired heading is calculated. When the difference is within the threshold range of the heading angle, the USV will navigate according to the actual heading. If the difference exceeds the threshold range of the heading angle, the difference is sent to the heading PID controller, which calculates and outputs the final heading value. The actual speed of the USV is obtained by the measuring equipment on board. The desired speed of the USV is obtained by sending commands from the telemetry and control terminal. The difference between the actual speed and the desired speed is calculated. When the difference is within the threshold range of the speed, the USV will navigate according to the actual speed. If the difference exceeds the threshold range of the speed, the difference is sent to the speed PID controller, which calculates and outputs the final speed value.

[0045] 4-3) The rudder angle movement is controlled by the output heading value. If the rudder angle control is within the safe range, the actual rudder angle is used for control. If the rudder angle control exceeds the safe range, the rudder angle is limited to -30° or +30°, and the unmanned vessel turns. If the difference between the actual heading and the desired heading is within the heading angle threshold range, the heading PID controller controls the rudder angle to center, and the heading is recalculated based on the rudder angle. The unmanned vessel then navigates according to the heading. Otherwise, the turning continues until the difference between the actual heading and the desired heading is within the heading angle threshold range. The engine speed is controlled by the output speed value. If the speed is within the threshold range, the vessel navigates at the actual speed. If the speed exceeds the threshold range, the speed PID controller controls the speed to keep it within the threshold range.

[0046] 4-4) The unmanned vessel navigates according to the final output heading and speed. During the navigation process, it enters step two in real time to calculate the heading and speed, control the rudder angle and speed, and feed back the rudder angle and speed information. This process is repeated in real time to achieve path tracking of the unmanned vessel.

[0047] An unmanned surface vessel path tracking system based on an improved LOS algorithm and adaptive PID, used to implement the tracking method, includes:

[0048] The measurement and control module is used to issue control commands;

[0049] The communication module is used for the exchange of data information between the telemetry and control terminal and the ship control terminal;

[0050] The main control module is used to receive task instructions from the telemetry and control terminal, perform task planning, and send the planned tasks to the flight control module.

[0051] The flight control module is used to receive tasks from the main control module, calculate the task based on the navigation and obstacle information obtained by the navigation and perception modules, and then send the calculated control signals to the steering control module.

[0052] The steering control module compares the control signals sent by the flight control module with the status signals fed back by the actuators, determines the motion information of the actuators based on the difference, and controls the motion of the actuators.

[0053] The navigation module is used to acquire real-time navigation information of the unmanned vessel, including heading, position, pitch, roll, and speed.

[0054] The perception module is used to acquire information about obstacles on the water surface, including their location, distance, speed, and heading.

[0055] An actuator is used to execute control commands.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0057] First, this invention improves the path tracking accuracy by modifying the traditional LOS guidance algorithm, taking into account the impact of unmanned vessel speed and turning angle on path tracking control. Specifically, in the guidance layer, the influence of external environment such as water flow and waves on the vessel during the straight-line tracking phase is considered, and the desired heading angle is compensated. During the turning tracking phase, considering the influence of turning angle and speed, a method using variable speed and variable radius tangent point circle parameters is adopted to achieve a smooth turning transition.

[0058] Secondly, considering the impact of the aquatic environment on the control of the unmanned vessel, this invention designs an adaptive PID controller to improve the accuracy of heading control. Specifically, in the control layer, the actual heading of the unmanned vessel is obtained based on the inertial navigation and other measurement equipment on board, and the difference is compared with the desired heading of the set path. An adaptive PID control method is then used to generate a control signal. In the execution layer, after receiving the control signal generated by the control layer, the actuators in the drive system make corresponding changes, so that the unmanned vessel sails according to the desired heading, ultimately achieving the effect of path tracking. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0060] Figure 1 This is a schematic diagram of the unmanned vessel control system of the present invention.

[0061] Figure 2 This is a schematic diagram of the unmanned vessel straight-line path tracking of the present invention.

[0062] Figure 3 This is a schematic diagram of the unmanned vessel turning path tracking of the present invention.

[0063] Figure 4 This is a schematic diagram of the PID control structure for the unmanned vessel of the present invention. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] Example 1

[0066] An unmanned surface vessel path tracking system based on an improved LOS algorithm and adaptive PID, such as Figure 1 As shown, it includes:

[0067] The measurement and control module is used to issue control commands, such as commands to start and stop shipboard equipment, and to issue and execute tasks; it is also used to display shipboard information, such as the engine speed, rudder position, reverse bucket position, heading, and position.

[0068] Communication module: Used for data exchange between the telemetry and control terminal and the ship control terminal, such as issuing mission instructions and uploading mission information, including but not limited to data transmission radio, image transmission radio, satellite communication, 4G / 5G communication module and other equipment;

[0069] Shipboard equipment mainly includes a main control module, navigation control module, rudder control module, navigation module, sensing module, and actuators. The main control module is mainly used to receive task commands from the telemetry and control terminal, perform task planning, and send the planned tasks to the navigation control module. The navigation control module is mainly used to receive tasks from the main control module, calculate the task based on navigation and obstacle information obtained from the navigation and sensing modules, and then send the calculated control signals (main engine speed, rudder angle, bucket position) to the rudder control module. The rudder control module mainly compares the control signals sent by the navigation control module with the status signals fed back by the actuators, judges the motion information of the actuators based on the difference, and controls the motion of the actuators. The navigation module is mainly used to acquire the unmanned vessel's navigation information in real time, including heading, position (latitude and longitude), pitch, roll, speed, etc. The sensing module is mainly used to acquire information on obstacles on the water surface, including position, distance, speed, heading, etc.

[0070] Example 2

[0071] An unmanned surface vessel path tracking method based on an improved LOS algorithm and adaptive PID includes:

[0072] Step 1: Plan the desired path based on the specific task requirements;

[0073] Step 2: In the outer ring guidance, an improved LOS guidance algorithm is used for path tracking. Specifically, in the straight-line tracking phase, the ship is affected by external environmental factors such as water flow and waves, and the desired heading angle is compensated. In the turning tracking phase, considering the influence of turning angle and speed, a method using variable speed and variable radius tangent circle parameters is used to achieve a smooth turning transition.

[0074] Step 3: In the inner loop control, the actual heading of the unmanned vessel is obtained from the inertial navigation and other measurement equipment on board the unmanned vessel. The difference is compared with the expected heading of the set path, and an adaptive PID control method is used to generate a control signal.

[0075] Step 4: In the execution layer, after receiving the control signal generated by the control layer, the actuators in the drive system make corresponding changes, so that the unmanned vessel sails in the desired course, ultimately achieving the effect of path tracking.

[0076] In step two, the straight path tracing is as follows: Figure 2 As shown:

[0077] The method for calculating the desired heading angle is as follows:

[0078] A series of waypoints P1, P2, ..., Pk-1, Pk, Pk+1, ..., Pn, This is the current waypoint. For the previous waypoint, The center position of the unmanned vessel is the location of the unmanned vessel. A circle is formed with the center position of the unmanned vessel as its center. Draw a circle with radius Pk-1, intersecting the line connecting Pk-1 and Pk at two points. Let the intersection point closer to Pk be denoted as . Then, the straight path tracking of the forward-looking circle satisfies the following formula:

[0079]

[0080] Expected path azimuth for:

[0081]

[0082] Unmanned boat arrives The distance between the points is:

[0083]

[0084] Unmanned boat arrives The azimuth of the point is:

[0085]

[0086] The lateral deviation of the unmanned vessel from the desired path for:

[0087]

[0088] Forward sight distance of traditional LOS guidance law Generally, the forward look-ahead distance is set to a fixed value based on experience. The value of can affect the convergence speed of path tracking to some extent. To improve the tracking performance, a variable look-ahead distance method is designed as follows: When the lateral deviation is large, i.e., greater than the radius of the look-ahead circle, to avoid right-angle regression to the desired path, the look-ahead distance is set to . As the unmanned surface vessel (USV) approaches the desired path, the lateral deviation decreases. At this point, it is desirable to increase the forward look-ahead distance to achieve smoother path tracking. To meet these requirements, the designed variable forward look-ahead distance must satisfy the following conditions:

[0089]

[0090] In the formula, For minimum forward sight distance, To maximize the forward sight distance, A constant that is greater than zero;

[0091] Then the expected heading angle of the unmanned ship The calculation formula is as follows:

[0092]

[0093] During path travel, unmanned surface vessels are susceptible to external environmental factors (wind, waves, currents), which can cause deviations in the course tracking process. To compensate for these course deviations, a Line of Sight (LOS) compensator based on the course deviation is designed as follows:

[0094]

[0095] In the formula, The deviation angle for heading tracking. To calculate the expected heading angle of the unmanned vessel, This is the actual heading angle of the unmanned vessel. For the heading angle that needs to be compensated, This represents the maximum steering angle of the unmanned vessel during navigation. This is the compensation coefficient for the deviation angle;

[0096] The expected final heading angle of the unmanned vessel is:

[0097]

[0098] Step two involves tracking the turning path, as follows: Figure 3 As shown:

[0099] The current path tracking point of the unmanned vessel is When the unmanned surface vessel meets the following conditions, it will immediately switch to tracking the next desired waypoint:

[0100]

[0101] When the unmanned surface vessel's path tracking reaches a stable phase, the lateral deviation... Smaller, compared to forward sight distance This can be ignored, and the radius of the foreseeable circle satisfies the following condition:

[0102]

[0103] At higher speeds, a turn angle less than 90° generally results in a smooth turn; however, a turn angle greater than 90° will cause system overshoot. At lower speeds, a turn angle less than 90° will result in premature turning due to the large forward sight radius; a turn angle greater than 90° will require a longer turn time.

[0104] First, to address the issue of system overshoot caused by excessively large turning angles, this invention proposes a turning strategy based on a variable radius tangent circle, which decomposes a large turning angle into three smaller turning angles, achieving a smooth transition during the turn:

[0105] point , , Let each point be an adjacent point on a desired path. , , For point The three virtual turning points at the location, among which point , The circle and line segment are respectively the point of tangency with variable radius. , The intersection (tangent point) of the points for The intersection of the angle bisector and the circle of tangency with a variable radius. , The coordinates of a point satisfy the following conditions:

[0106]

[0107]

[0108] At this point, the coordinates of the center of the circle at the point of tangency with a variable radius The following conditions must be met:

[0109]

[0110] but The coordinates of a point satisfy the following conditions:

[0111]

[0112] When the turning angle is greater than 90°, path tracking is performed on the flight path. , Tracking is converted into route tracking , , , Tracking enables smooth transitions during turns.

[0113] Secondly, to address the issue of premature turning due to an excessively large forward sight radius when the speed is low and the turning angle is less than 90°, a turning strategy combining speed and a variable forward sight radius is proposed. Specifically, when the turning angle is less than 90°, the forward sight radius is adjusted based on the actual speed of the current tracking path. Higher speeds result in a greater increase in forward sight distance, and vice versa. The variable forward sight radius satisfies the following conditions:

[0114]

[0115] In the formula, For minimum forward sight distance, To maximize the forward sight distance, The current actual speed, This is the maximum speed of the unmanned vessel.

[0116] In step three, the inner loop control is as follows: Figure 4 As shown:

[0117] In the inner-loop control of the unmanned surface vessel (USV), an adaptive PID control method is used to generate control signals to achieve motion control. The motion control of the USV is divided into speed control and heading control; therefore, separate speed controllers and heading controllers are designed. Compared to heading control, speed control is relatively simple and can be implemented using traditional PID control. The PID calculation formula for speed control is as follows:

[0118]

[0119] In the formula, The proportional gain of the PID controller; The integral coefficient of the PID controller. This is the integral error; The derivative coefficients of the PID controller are... This is the differential error; This represents the difference between the current actual speed and the target speed. This is the speed difference calculated at the previous moment. The speed value output for speed control.

[0120] The PID calculation formula for adaptive heading control is as follows:

[0121]

[0122] In the formula, The proportional gain of the PID controller; The integral coefficient of the PID controller. The range of values ​​is , This is the integral error; The derivative coefficients of the PID controller are... The range of values ​​is , This is the differential error; This is the difference between the current heading and the target heading. This is the heading difference calculated at the previous moment. The heading value output by the heading control.

[0123] The specific operation steps of the execution layer in step four are as follows:

[0124] 4-1) Construct a heading PID controller and a speed PID controller respectively, set the safe range of the rudder angle and the threshold of the heading angle, and set the safe range and threshold of the main engine speed and RPM respectively. The safe range of the rudder angle is -30° to +30°, and the threshold range of the heading angle is 0.5° to 1°; the safe range of the main engine RPM is set according to the main engine's technical instructions, and the threshold is set to 0.05 to 0.1 times the maximum RPM.

[0125] 4-2) The actual heading of the unmanned surface vessel (USV) is obtained through the measurement equipment onboard the USV. The desired heading is obtained by issuing commands from the telemetry and control terminal. The difference between the actual and desired headings is calculated. When the difference is within the heading angle threshold range, the USV will navigate according to the actual heading. If the difference exceeds the heading angle threshold range, the difference is sent to the heading PID controller, which calculates and outputs the final heading value. Similarly, the actual speed of the USV is obtained through the measurement equipment onboard the USV. The desired speed is obtained by issuing commands from the telemetry and control terminal. The difference between the actual and desired speeds is calculated. When the difference is within the speed threshold range, the USV will navigate according to the actual speed. If the difference exceeds the speed threshold range, the difference is sent to the speed PID controller, which calculates and outputs the final speed value.

[0126] 4-3) The rudder angle movement is controlled by the output heading value. If the rudder angle control is within the safe range, the actual rudder angle is used. If the rudder angle control exceeds the safe range, the rudder angle is limited to -30° or +30°, and the unmanned surface vessel (USV) turns. If the difference between the actual heading and the desired heading is within the heading angle threshold range, the heading PID controller controls the rudder angle to center, and the heading is recalculated based on the rudder angle. The USV then navigates according to the heading. Otherwise, the turning continues until the difference between the actual heading and the desired heading is within the heading angle threshold range. The engine speed is controlled by the output speed value. If the speed is within the threshold range, the USV navigates at the actual speed. If the speed exceeds the threshold range, the speed PID controller controls the speed to keep it within the threshold range.

[0127] 4-4) The unmanned vessel navigates according to the final output heading and speed. During the navigation process, it enters step two in real time to calculate the heading and speed, control the rudder angle and speed, and feed back the rudder angle and speed information. This process is repeated in real time to achieve path tracking of the unmanned vessel.

[0128] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A path tracking method for unmanned surface vessels based on an improved LOS algorithm and adaptive PID control, characterized in that, Includes the following steps: Step 1) Based on the specific task requirements, plan the desired path; Step 2) In outer-loop guidance, an improved LOS guidance algorithm is used for path tracking. The desired heading angle is compensated during the straight-line tracking phase. During the turning tracking phase, a method using variable speed and variable radius tangent circle parameters is used to achieve a smooth turning transition. Methods for compensating for the desired heading angle during the straight-line tracking phase include: 2-1) The designed variable forward sight distance is set to a value that is large when the lateral deviation is greater than the radius of the forward sight circle. As the unmanned surface vessel (USV) approaches the desired path, the lateral deviation decreases. At this point, it is desirable to increase the forward look-ahead distance to achieve smoother path tracking. The variable forward look-ahead distance must meet the following conditions: ； In the formula, For minimum forward sight distance, To maximize the forward sight distance, A constant that is greater than zero. The lateral deviation of the unmanned vessel from the desired path; 2-2) Calculate the final expected heading angle of the unmanned vessel. : ； ； ； ； in, The deviation angle for heading tracking. To calculate the expected heading angle of the unmanned vessel, This is the actual heading angle of the unmanned vessel. For the heading angle that needs to be compensated, This represents the maximum steering angle of the unmanned vessel during navigation. This is the compensation coefficient for the deviation angle; During the turning tracking phase, a method using variable speed and variable radius tangent point parameters is employed to achieve a smooth turning transition. Specifically, this includes: 2-3) When the speed is high and the turning angle is greater than 90°, the large turning angle is decomposed into three smaller turning angles, and path tracking is performed on the route. , Tracking is converted into route tracking , , , Tracking enables smooth transitions during turns: 2-4) When the speed is low and the turning angle is less than 90°, the forward sight radius will be adjusted according to the actual speed of the current tracking path. The higher the speed, the greater the increase in forward sight distance; conversely, the lower the speed, the smaller the increase in forward sight distance. The variable forward sight radius satisfies the following conditions: ； In the formula, For minimum forward sight distance, To maximize the forward sight distance, The current actual speed, This is the maximum speed of the unmanned vessel. Step 3) In the inner loop control, the actual heading of the unmanned vessel is obtained from the inertial navigation measurement equipment on board the unmanned vessel. The difference is compared with the expected heading of the set path. The adaptive PID control method is used to generate the control signal to realize the motion control of the unmanned vessel. The speed controller and heading controller are designed respectively. The PID calculation formula for adaptive speed control is as follows: ； In the formula, The proportional gain of the PID controller; The integral coefficient of the PID controller. This is the integral error; The derivative coefficients of the PID controller are... This is the differential error; This represents the difference between the current actual speed and the target speed. This is the speed difference calculated at the previous moment. The speed value output by the speed control. The PID calculation formula for adaptive heading control is as follows: ； In the formula, The proportional gain of the PID controller; The integral coefficient of the PID controller. The range of values ​​is , This is the integral error; The derivative coefficients of the PID controller are... The range of values ​​is , This is the differential error; This represents the difference between the current heading and the target heading. This is the heading difference calculated at the previous moment. The heading value output by the heading control; Step 4) In the execution layer, after receiving the control signal generated by the control layer, the actuators in the drive system make corresponding changes to enable the unmanned vessel to sail in the desired course, ultimately achieving path tracking.

2. The unmanned vessel path tracking method based on improved LOS algorithm and adaptive PID control according to claim 1, characterized in that, In 2-3), the larger turning angle is broken down into three smaller turning angles, specifically: point , , Let each point be an adjacent point on a desired path. , , Let point be one of the three virtual turning points at point , where point is the most virtual turning point. , The circle and line segment are respectively the point of tangency with variable radius. , The intersection point, point for The intersection of the angle bisector and the circle of tangency with a variable radius; in , The coordinates of a point satisfy the following conditions: ； ； At this point, the coordinates of the center of the circle at the point of tangency with a variable radius The following conditions must be met: ； but The coordinates of a point satisfy the following conditions: 。 3. The unmanned vessel path tracking method based on improved LOS algorithm and adaptive PID control according to claim 1, characterized in that, The specific operation steps of the execution layer in step 4) are as follows: 4-1) Construct a heading PID controller and a speed PID controller respectively, set the safe range of the rudder angle and the threshold of the heading angle, and set the safe range and threshold of the main engine speed and RPM respectively; the safe range of the rudder angle is -30° to +30°, and the threshold range of the heading angle is 0.5° to 1°; the safe range of the main engine RPM is set according to the main engine's technical instructions, and the threshold is set to 0.05 to 0.1 times the maximum RPM; 4-2) The actual heading of the unmanned vessel is obtained by the measuring equipment carried by the unmanned vessel, and the desired heading of the unmanned vessel is obtained by sending a command through the telemetry and control terminal. The difference between the actual heading and the desired heading is calculated. When the difference is within the threshold range of the heading angle, the unmanned vessel will navigate according to the actual heading. If the difference exceeds the threshold range of the heading angle, the difference is sent to the heading PID controller, which calculates and outputs the final heading value. The actual speed of the unmanned vessel is obtained by the measuring equipment on board the unmanned vessel, and the desired speed of the unmanned vessel is obtained by sending a command through the telemetry and control terminal. The difference between the actual speed and the desired speed is calculated. When the difference is within the speed threshold range, the unmanned vessel will sail according to the actual speed; if the difference exceeds the speed threshold range, the difference will be sent to the speed PID controller, which will calculate and output the final speed value. 4-3) The rudder angle movement is controlled by the output heading value. If the rudder angle control is within the safe range of the rudder angle, the actual rudder angle is used for control. If the rudder angle control exceeds the safe range of the rudder angle, the rudder angle is limited to -30° or +30°, and the unmanned vessel turns. If the difference between the actual heading and the desired heading is within the heading angle threshold range, the heading PID controller controls the rudder angle to center the rudder angle. The heading is then calculated based on the rudder angle, and the unmanned vessel navigates according to the heading. Otherwise, continue turning until the difference between the actual heading and the desired heading is within the threshold range of the heading angle; the output speed value controls the engine speed. If the speed is controlled within the threshold range, then sail at the actual speed. If the speed exceeds the threshold range, then the speed is controlled by the speed PID controller to keep the speed within the threshold range. 4-4) The unmanned vessel navigates according to the final output heading and speed. During the navigation process, it enters step 4-2) in real time to calculate the heading and speed, control the rudder angle and speed, and feed back the rudder angle and speed information. This process is repeated in real time to achieve path tracking of the unmanned vessel.

4. An unmanned surface vessel path tracking system based on an improved LOS algorithm and adaptive PID control, for implementing the tracking method as described in any one of claims 1-3, characterized in that, include: The measurement and control module is used to issue control commands; The communication module is used for the exchange of data information between the telemetry and control terminal and the ship control terminal; The main control module is used to receive task instructions from the telemetry and control terminal, perform task planning, and send the planned tasks to the flight control module. The flight control module is used to receive tasks from the main control module, calculate the task based on the navigation and obstacle information obtained by the navigation and perception modules, and then send the calculated control signals to the steering control module. The steering control module compares the control signals sent by the flight control module with the status signals fed back by the actuators, determines the motion information of the actuators based on the difference, and controls the motion of the actuators. The navigation module is used to acquire real-time navigation information of the unmanned vessel, including heading, position, pitch, roll, and speed. The perception module is used to acquire information about obstacles on the water surface, including their location, distance, speed, and heading. An actuator is used to execute control commands.

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