A ship path tracking control system based on bias compensation

Abstract

The application discloses a ship path tracking control system based on deviation compensation, and relates to the technical field of ships.The system is built based on ship propulsion motor control units, automatic / follow-up steering instruments and other ship motion control modules, combined with a navigation decision module and a path tracking control module, and the path tracking control module controls the ship motion control module by using an improved ship path tracking control method.The improved ship path tracking control method optimizes the expected heading by compensating for longitudinal deviation on the basis of the traditional LOS guidance method, so that the target heading angle planned in real time is more in line with the motion characteristics of ships, especially medium and large under-actuated ships, the ship path tracking deviation can be reduced, the path tracking convergence speed can be accelerated, the ship tracking path navigation mileage can be reduced, and the time spent on tracking the path can be reduced.

Description

Technical Field

[0001] This application relates to the field of marine technology, and in particular to a ship path tracking control system based on deviation compensation. Background Technology

[0002] With the continuous development of ship intelligence, more and more countries and shipping companies are focusing on autonomous ship navigation, and ship path tracking technology is the key to achieving autonomous navigation.

[0003] Currently, the mainstream technology for achieving ship path tracking is the Line-of-Sight (LOS) guidance method. However, the LOS guidance method is more suitable for small ships with small hull size, strong driving performance, and flexible maneuverability. Medium and large ships have poor maneuverability due to their single engine and single propeller, and the nonlinear and uncertain nature of the system motion. When using the LOS guidance method, there are often a series of problems such as slow tracking convergence speed and long tracking path mileage, resulting in unsatisfactory path tracking performance. Summary of the Invention

[0004] To address the aforementioned problems and technical requirements, the applicant proposes a ship path tracking control system based on deviation compensation. The technical solution of this application is as follows:

[0005] A ship path tracking control system based on deviation compensation includes a navigation decision module, a path tracking control module, and a ship motion control module. The navigation decision module performs path planning to determine the ship's current tracking point position P. b The path tracking control module obtains the current tracking point position P. b And implement the following ship path tracking control method:

[0006] Determine the longitudinal deviation y of the ship's real-time position P0 relative to the target path. e The target path is the starting tracking point P of the ship path tracking. a Point to the current tracking point position P b A straight path;

[0007] For longitudinal deviation y e The optimized longitudinal deviation y is obtained by performing deviation compensation. ec ;

[0008] Based on the optimized longitudinal deviation y ec Determine the target heading angle by combining the ship's line-of-sight distance Δ

[0009] According to the target heading angle Control the ship's motion control module and execute again to determine the longitudinal deviation y of the ship's real-time position P0 relative to the target path.e The steps continue until the ship's real-time position P0 reaches the current tracking point position P. b .

[0010] A further technical solution is that when the ship's real-time position P0 is to the left of the target path, the longitudinal deviation y e The longitudinal deviation y is positive when the ship's real-time position P0 is to the right of the target path. e It is negative; and the longitudinal deviation y e absolute value |y e | is the projected distance between the ship's real-time position P0 and the target path.

[0011] The further technical solution is to obtain the optimized longitudinal deviation y. ec The methods include:

[0012] Based on the ship's current tracking point position P b longitudinal deviation y during the process e The maximum value of y emax absolute value |y emax Determine the compensation coefficient k;

[0013] Determine the compensation amount V c =k(|y emax |-|y e |) and obtain the optimized longitudinal deviation Among them, the compensation amount V c <|y e |

[0014] Its further technical solution is that when |y emax When |y ≤ λ1, the compensation coefficient k = 0; when λ1 < |y emax When |≤λ2, the compensation coefficient k and |y emax | Shows a positive correlation; when |y emax When |>λ2, the compensation coefficient k and |y emax | Shows a negative correlation coefficient.

[0015] A further technical solution involves determining the longitudinal deviation y of the ship's real-time position P0 relative to the target path. e The methods include:

[0016] The target path angle is obtained by determining the angle between the target path and true north using an inertial coordinate system. Current tracking point position P b The coordinates in the inertial coordinate system are (x b ,y b ), starting tracking point position P a The coordinates in the inertial coordinate system are (x a ,ya );

[0017] Based on the ship's real-time position P0 and target path angle α k The longitudinal deviation y was calculated. e .

[0018] A further technical solution involves calculating the longitudinal deviation y. e The method includes calculating y according to the following formula e =sin(α) k (x0-x) a )+cos(α k (y0-y) a The real-time position of the ship P0 in the inertial coordinate system is (x0, y0).

[0019] Its further technical solution is to determine the target heading angle. The methods include:

[0020] Determine the target heading angle α k It is the target path angle and represents the angle between the target path and due north.

[0021] The further technical solution is to determine the obtained target heading angle. The ship's real-time position P0 points to the LOS target point P on the target path. los The angle between the line connecting the two points and due north, and the LOS target point P on the target path. los The distance between the real-time position P0 of the ship and the projection point on the target path is the line-of-sight distance Δ.

[0022] A further technical solution is that the ship motion control module includes a motor control unit and a steering unit, and the method by which the path tracking control module controls the ship motion control module includes:

[0023] Real-time ship heading angle With the target heading angle The angle difference is input to the PID controller to obtain the target rudder angle, and the steering unit is controlled to perform heading control according to the target rudder angle;

[0024] The speed difference between the real-time speed and the target speed is input into the PID control to obtain the speed control command, and the motor control unit is controlled to perform speed control according to the speed control command.

[0025] The further technical solution is that the system also includes a switch, an expansion module, and a distributed data acquisition and processing module. The navigation decision module, the path tracking control module, and the expansion module are all connected to the switch. The switch is connected to the distributed data acquisition and processing module, and the distributed data acquisition and processing module is connected to each ship motion control module. The navigation decision module, the path tracking control module, and the switch are all designed with redundancy backup. The expansion module is used to provide expansion interfaces, and the distributed data acquisition and processing module is used to perform data format conversion.

[0026] The beneficial technical effects of this application are:

[0027] This application discloses a ship path tracking control system based on deviation compensation. The system is built on the ship motion control modules such as the ship propulsion motor control unit and the automatic / follow-up steering system, combined with the navigation decision module and the path tracking control module. The path tracking control module uses an improved ship path tracking control method to control the ship motion control module. This improved ship path tracking control method optimizes the desired course by compensating for longitudinal deviation on the basis of the traditional LOS guidance method, so that the target course angle planned in real time is more in line with the motion characteristics of ships, especially medium and large under-driven ships. It can reduce the ship path tracking deviation, accelerate the path tracking convergence speed, reduce the ship's tracking path navigation distance, and reduce the tracking path time.

[0028] The system also features redundant backups to improve reliability, and reserves expansion modules to enhance the stability and scalability of the path tracking control system. Attached Figure Description

[0029] Figure 1 This is a system architecture diagram of a ship path tracking control system according to one embodiment of this application.

[0030] Figure 2 This is a flowchart of a method in one embodiment of the present application whereby the path tracking control module executes the ship path tracking control method and controls the ship motion control module to perform heading control.

[0031] Figure 3 This is a schematic diagram illustrating an application scenario of the path tracking control module in executing a ship path tracking control method in one embodiment of this application.

[0032] Figure 4 The compensation coefficient and longitudinal deviation y are obtained by fitting in one instance. e The maximum value of y emax absolute value y emax | Relationship curve diagram.

[0033] Figure 5This is a simulation comparison diagram of the navigation trajectory when using the traditional LOS guidance method and the ship path tracking control method of this application in a simulation example.

[0034] Figure 6 This is a simulation comparison diagram of the ship's heading angle using the traditional LOS guidance method and the ship path tracking control method of this application in a simulation example.

[0035] Figure 7 This is a simulation comparison diagram of longitudinal deviation when using the traditional LOS guidance method and the ship path tracking control method of this application in a simulation example. Detailed Implementation

[0036] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0037] This application discloses a ship path tracking control system based on deviation compensation. Please refer to [link / reference]. Figure 1 The schematic diagram shows that the ship path tracking control system includes a navigation decision module 1, a path tracking control module 2, and a ship motion control module 3. The navigation decision module 1 determines the ship's current tracking point position P using various path planning algorithms. b The path tracking control module 2 is used to control the ship motion control module 3 so that the ship reaches the current tracking point position P. b The ship motion control module 3 includes a motor control unit 31 and a steering unit 32. The motor control unit 31 further includes a propulsion motor control unit and a ram thruster motor control unit, and the steering unit 32 further includes a servo steering unit and an autopilot unit. The path tracking control module 2 controls the ship motion control module 3 by sending speed control commands to the motor control unit 31 to control the ship's speed and sending course control commands to the steering unit 32 to control the ship's course.

[0038] like Figure 1 As shown, the system also includes a switch 4, an expansion module 5, and a distributed data acquisition and processing module 6. The navigation decision module 1, the path tracking control module 2, and the expansion module 5 are all connected to the switch 4. The switch 4 is connected to the distributed data acquisition and processing module 6, which in turn is connected to each of the ship motion control modules 3. The distributed data acquisition and processing module 6 is used for data format conversion, including converting the speed control commands and heading control commands issued by the path tracking control module 2 before sending them to the corresponding ship motion control modules 3. The distributed data acquisition and processing module 6 supports multiple types of hardware interfaces. Furthermore, the system also provides multiple types of expansion interfaces through the expansion module 5 to facilitate functional expansion.

[0039] In one embodiment, the navigation decision module 1, the path tracking control module 2, and the switch 4 are all designed with redundancy, such as... Figure 1 As shown, the navigation decision module 1, path tracking control module 2, and switch 4 all employ primary and backup dual redundancy. The navigation decision module 1 and path tracking control module 2 can actually be implemented based on servers or server clusters.

[0040] Path tracking control module 2 obtains the current tracking point position P planned by navigation decision module 1. b The following ship path tracking control method is executed, and ship motion control module 3 is controlled. Please refer to [link / reference]. Figure 2 The flowchart shown and Figure 3 The navigation diagram shown illustrates that the method includes the following steps:

[0041] Step 1: Determine the longitudinal deviation y of the ship's real-time position P0 relative to the target path. e .

[0042] An inertial coordinate system parallel to the reference sea level is established with due north as the y-axis and due east as the x-axis. The ship's real-time position P0 is represented by coordinates (x0, y0) in the inertial coordinate system, and the initial tracking point position P... a Coordinates (x) in the inertial coordinate system a ,y a ) and the current tracking point location P b Coordinates (x) in the inertial coordinate system b ,y b All of these are known. The starting tracking point location P in this application is... a This refers to the location of the previous tracking point, or the location of the ship's starting point.

[0043] The target path is the starting tracking point P of the ship path tracking. a Point to the current tracking point position P b The straight path. Determine the obtained longitudinal deviation y. e It can be positive or negative. This application defines the longitudinal deviation y as follows: when the ship's real-time position P0 is to the left of the target path. e The longitudinal deviation y is positive when the ship's real-time position P0 is to the right of the target path. e It is negative. And the longitudinal deviation y e absolute value |y e |This refers to the projected distance between the ship's real-time position P0 and the target path, for example... Figure 3 Longitudinal deviation y e It is positive.

[0044] Determine the longitudinal deviation y of the ship's real-time position P0 relative to the target path. e The methods include:

[0045] The target path angle is obtained by determining the angle between the target path and true north using an inertial coordinate system. Then, based on the ship's real-time position P0 and the target path angle α k The longitudinal deviation y was calculated. e This includes calculating y according to the following formula. e =sin(α) k (x0-x) a )+cos(α k (y0-y) a ).

[0046] Step 2, for the longitudinal deviation y e The optimized longitudinal deviation y is obtained by performing deviation compensation. ec The goal of deviation compensation is to make the ship's real-time position P0 approach the target path; therefore, the optimized longitudinal deviation y ec The absolute value is generally less than the longitudinal deviation y. e The deviation value.

[0047] However, if we consider the longitudinal deviation y e Excessive deviation compensation can lead to overshoot, causing the ship to sail parallel to the target path while following one side of it, resulting in a fixed longitudinal deviation and difficulty converging to the target path. To avoid this overshoot, the longitudinal deviation y... e Compensation amount V when performing deviation compensation c <|y e |, here is the compensation amount V c It is positive.

[0048] In one embodiment, the compensation amount V c =k(|y emax |-|y e |), then the optimized longitudinal deviation is obtained. |y emax |This is the ship tracking the current tracking point P. b longitudinal deviation y during the process e The maximum value of y emax The absolute value of the longitudinal deviation y during the tracking control process. e The trend is that the longitudinal deviation y decreases continuously, so that the ship's real-time position P0 eventually lies on the target path and the ship's navigation path converges to the target path. e The maximum value of y emax The absolute value usually appears at the starting position P of the current tracking point. b When, that is, |y emax Generally, this occurs when the ship reaches the previous tracking point and begins tracking the current tracking point.b time|y e |

[0049] The value of the compensation coefficient k determines the compensation amount V. c The magnitude of y determines the effect on the longitudinal deviation y. e The speed of deviation compensation, in one embodiment, is determined by the compensation coefficient k based on the ship's position P at the current tracking point. b |y in the process emax | to determine, and the value of the compensation coefficient k is related to |y emax The relationship between | satisfies the following rule: (1) When |y emax When |≤λ1, the compensation coefficient k=0, that is, when |y emax When the value is very small, the actual longitudinal deviation y is not... e Deviation compensation is performed, and tracking control is carried out according to the conventional LOS guidance method. (2) When λ1 < |y emax When |≤λ2, the compensation coefficient k and |y emax | shows a positive correlation with a large slope, meaning that in this stage, the compensation coefficient k increases with |y. emax | increases rapidly as |y increases. (3) When |y emax When |>λ2, the compensation coefficient k and |y emax | shows a negative correlation coefficient, meaning that in this stage, the compensation coefficient k increases with |y. emax | decreases as it increases.

[0050] The value of the compensation coefficient k is related to |y emax The above relationship between the two can avoid the situation where the ship's navigation trajectory converges to a path close to the target path but fails to converge to the target path, thus giving this application a better tracking and control effect.

[0051] The value of the compensation coefficient k is related to |y emax The specific curve relationship between |y| can be obtained in advance by establishing a fit through simulation data. For example, in one instance, the value of the compensation coefficient k is related to |y|. emax The relationship curve is obtained by Emilet interpolation of the simulation data, and the relationship curve is as follows: Figure 4 As shown.

[0052] Step 3, based on the optimized longitudinal deviation y ec Determine the target heading angle by combining the ship's line-of-sight distance Δ

[0053] In one embodiment, the target heading angle is determined. α k It is the target path angle and represents the angle between the target path and due north. It is calculated according to the arctangent function mentioned above. The line-of-sight distance Δ of the ship is a fixed value that is known in advance.

[0054] The target heading angle is obtained in this step. That is, the real-time position P0 of the ship points to the LOS target point P on the target path. los (x los ,y los The angle between the line connecting () and due north, and the LOS target point P on the target path. los The distance between the real-time position P0 of the ship and the projection point on the target path is the line-of-sight distance Δ.

[0055] This calculation formula shows that when the optimized longitudinal deviation y ec When approaching 0, the target heading angle Converging at the target path angle α k This means that the ship's trajectory converges to the target path.

[0056] Step 4, according to the target heading angle Ship motion control module.

[0057] After obtaining the target heading angle Then, the path tracking control module determines the target heading angle. The module that generates heading control commands controls the ship's motion, specifically the steering unit. For example... Figure 3 As shown, in actual navigation, the ship's real-time heading U and real-time bow H do not coincide; therefore, the ship's real-time heading angle... With the ship's real-time bow angle They are not equal; the difference between them is the drift angle β. The ship's real-time heading angle. It is the angle between the ship's real-time heading U and true north, the ship's real-time bow angle. It is the angle between the ship's real-time heading H and due north.

[0058] In one embodiment, the path tracking control module employs a PID control method to measure the ship's real-time bow angle. With the target heading angle The angle difference is input to the PID controller to obtain the target rudder angle, and the steering unit is controlled to perform heading control according to the target rudder angle, so that the navigation trajectory gradually converges to the target path.

[0059] In addition to controlling the steering unit for heading control, the path tracking control module also inputs the speed difference between the real-time speed and the target speed into the PID control to obtain speed control commands, and controls the motor control unit to perform speed control according to the speed control commands.

[0060] When the ship's real-time position P0 reaches the current tracking point position P bAt that time, complete the tracking of the current tracking point position P. b The ship can be tracked, and then the position of the next tracking point can be obtained. This process can be repeated to track the next tracking point, or the navigation can be terminated directly. When the ship's real-time position P0 has not reached the current tracking point position P... b Then, repeat steps 1 to 4 above until the ship's real-time position P0 reaches the current tracking point position P. b .

[0061] In one simulation example, the comparison simulation diagram of the navigation trajectory is as follows: Figure 5 As shown, 51 represents the target path, 52 represents the navigation trajectory when using the traditional LOS guidance method for path tracking control, and 53 represents the navigation trajectory when using the method of this application for path tracking control. (Boat bow angle) The comparison simulation diagrams are as follows Figure 6 As shown, 61 represents the ship's heading angle when using the traditional LOS guidance method for path tracking control. The curve 62 represents the ship's heading angle when using the method of this application for path tracking control. The curve showing the change in longitudinal deviation y. e The comparison simulation diagrams are as follows Figure 7 As shown, 71 represents the longitudinal deviation y when using the traditional LOS guidance method for path tracking control. e The curve 72 represents the longitudinal deviation y when using the method of this application for path tracking control. e The curve showing the change. Through... Figure 5-7 The comparative simulation diagrams also show that the method in this application optimizes the desired course by compensating for longitudinal deviation based on the LOS guidance method. Compared with the traditional LOS guidance method, it can increase the convergence speed of ship path tracking, reduce the ship's tracking path mileage, and save the time spent on tracking the path.

[0062] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A ship path tracking control system based on deviation compensation, characterized in that, The ship path tracking control system includes a navigation decision module, a path tracking control module, and a ship motion control module. The navigation decision module performs path planning to determine the ship's current tracking point position. ; The path tracking control module obtains the current tracking point position. And implement the following ship path tracking control method: Determine the real-time position of the vessel Longitudinal deviation relative to the target path The target path is the starting tracking point location for ship path tracking. Point to the current tracking point position A straight path; Regarding the longitudinal deviation The optimized longitudinal deviation is obtained by performing deviation compensation. ; Based on the optimized longitudinal deviation Combined with the ship's line of sight distance Determine the target heading angle ; According to the target heading angle Control the ship motion control module and execute the process of determining the ship's real-time position again. Longitudinal deviation relative to the target path Steps until the ship's real-time position Reaching the current tracking point location ; When the ship's real-time position When located on the left side of the target path, longitudinal deviation The value is positive when the real-time position of the ship is positive. When located on the right side of the target path, longitudinal deviation It is negative; and the longitudinal deviation is negative. absolute value The real-time position of the ship Projected distance between the target path and the target path; Optimized longitudinal deviation The methods include: Based on the ship's current tracking point position longitudinal deviation during the process maximum value absolute value Determine the compensation coefficient ; when At that time, compensation coefficient ; when At that time, compensation coefficient and There is a positive correlation; when At that time, compensation coefficient and There is a negative correlation; Determine the amount of compensation And the optimized longitudinal deviation was obtained. Among them, the amount of compensation ; Determine the real-time position of the vessel Longitudinal deviation relative to the target path The methods include: The target path angle is obtained by determining the angle between the target path and due north using an inertial coordinate system. Current tracking point location The coordinates in the inertial coordinate system are Starting tracking point location The coordinates in the inertial coordinate system are ; Based on the ship's real-time location and target path angle Longitudinal deviation was calculated .

2. The system according to claim 1, characterized in that, Longitudinal deviation was calculated The method includes calculating according to the following formula Real-time location of the ship The coordinates in the inertial coordinate system are .

3. The system according to claim 1, characterized in that, Determine the target heading angle The methods include: Determine the target heading angle , It is the target path angle and represents the angle between the target path and the due north direction.

4. The system according to claim 1, characterized in that, Determine the target heading angle The real-time position of the ship Pointing to the LOS target point on the target path The angle between the line connecting the two points and due north, and the LOS target point on the target path. With the real-time position of the ship The distance between projection points on the target path is the line-of-sight distance. .

5. The system according to claim 1, characterized in that, The ship motion control module includes a motor control unit and a steering unit, and the method by which the path tracking control module controls the ship motion control module includes: Real-time ship heading angle With the target heading angle The angle difference is input to the PID controller to obtain the target rudder angle, and the steering unit is controlled to perform heading control according to the target rudder angle; The speed difference between the real-time speed and the target speed is input into the PID control to obtain the speed control command, and the motor control unit is controlled to perform speed control according to the speed control command.

6. The system according to claim 1, characterized in that, The system also includes a switch, an expansion module, and a distributed data acquisition and processing module. The navigation decision module, path tracking control module, and expansion module are all connected to the switch. The switch is connected to the distributed data acquisition and processing module, which is connected to each ship motion control module. The navigation decision module, path tracking control module, and switch are all designed with redundancy. The expansion module provides an expansion interface, and the distributed data acquisition and processing module performs data format conversion.

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