Ship track tracking control method based on waypoint route

Abstract

The invention discloses a ship track tracking control method based on waypoint routes. The ship track tracking control method based on the waypoint route comprises the following steps: setting waypoints and switching points near the waypoints; whether the ship meets a guidance switching condition or not is judged, and when the ship meets the guidance switching condition, a virtual transverse adjustment guidance law is started; when the ship does not meet the guidance switching condition, a self-adaptive sight guidance law is started; setting a flight path tracking controller and a preset performance index; and controlling the ship to track the expected path based on the track tracking controller and a preset performance index. According to the ship track tracking control method based on the waypoint route, a hybrid guidance law based on self-adaptive sight guidance and virtual transverse adjustment guidance is adopted, and the problem of ship waypoint steering overshoot is solved.

Description

Technical Field

[0001] The present application relates to the field of ship motion control, and in particular to a ship track tracking control method based on waypoint routes. Background Art

[0002] Path tracking and track tracking are essentially the same type of engineering tasks. In the field of control engineering, it is usually called path tracking, and for navigation engineering, it is more appropriate to call it track tracking. For ship track tracking tasks, the current mainstream methods are mainly divided into two parts: guidance and control. In the existing guidance technology, the guidance algorithm mainly includes the line of sight (LOS) algorithm and its improved method, virtual guidance, etc.

[0003] In the field of ship motion control, the power system is mainly configured on the propeller and rudder, providing forward thrust and turning torque respectively. For the logic virtual ship (LVS), the control command is calculated by the control system in real time according to the relative relationship between the ship's attitude and the reference position, and is transmitted to the actuator system. In order to save the signal transmission load pressure from the controller to the actuator and avoid frequent manipulation of the actuator, an underactuated autonomous surface vehicle (ASV) path tracking control method based on input event triggering has been proposed in the existing algorithm.

[0004] Specifically, the ASV path tracking control method based on input event triggering uses a separation method to establish a three-degree-of-freedom mathematical model for the ASV; the backstepping method is used to design the controller, and the radial basis function neural network is used to approximate the uncertainty of the model structure online. The nonlinear mathematical model of the ASV can be expressed as Equation (1) and Equation (2).

[0005] (1); (2); in, x Indicates the abscissa value of the ship; Represents the time first derivative of the ship's abscissa value; y Indicates the vertical coordinate value of the ship, represents the time first derivative of the ordinate value of the ship; Ψ Indicates the heading angle of the ship; Represents the time first-order derivative of the ship's heading angle; ( x , y , Ψ ) represents the position coordinates and heading angle of the ship; u Indicates the vertical speed; represents the time first derivative of the surge velocity;v Indicates the sway speed; represents the time first derivative of the sway velocity; r represents the yaw angular velocity; It represents the time first-order derivative of the yaw angular velocity; m u represents the additional mass on the longitudinal freedom degree; m v represents the additional mass in the sway degree of freedom; m r represents the additional mass on the pitching degree of freedom; d wi Indicates the interference force of the external environment. i = u , v , r ;in, d wu It indicates the interference force on the longitudinal freedom degree of the external environment; d wv It represents the disturbance force on the lateral freedom degree of the external environment; d wr Indicates the disturbance force of the external environment on the yaw freedom; f u (v) Represents the nonlinear terms on the longitudinal degrees of freedom in the model; f v (v) represents the nonlinear terms on the sway degrees of freedom in the model; f r (v) represents the nonlinear term on the yaw degree of freedom in the model; represents the control input parameters of the propeller; Indicates the control input parameters of the servo; T u Indicates the gain of controlling the input host speed; F r Indicates the gain of controlling the input rudder angle; n Indicates the host speed; δ Represents the rudder angle.

[0006] The reference route can be generated by LVS, and the corresponding guidance law can be constructed according to the position relationship between LVS and the actual ship, as shown in formula (3).

[0007] ;in, ѱ r represents the reference heading, , ; x eIt represents the coordinate error between the virtual ship and the actual ship on the X-axis in the inertial coordinate system; y e represents the coordinate error between the virtual ship and the actual ship on the Y axis in the inertial coordinate system; x d Indicates the horizontal coordinate value of the virtual ship; y d Indicates the vertical coordinate value of the ship.

[0008] Real-time heading error through Obtain, among which, ѱ is the ship's pitch angle, ѱ e Indicates the real-time heading error, ѱ r represents the desired ship heading angle; in order to stabilize the real-time heading error, the virtual control law on the forward degree of freedom and the virtual control law on the bowing degree of freedom are obtained through equation (4).

[0009] (4); in, α u represents the virtual control law on the forward degree of freedom; α r represents the virtual control law on the bow pitch degree of freedom; k x is a set control parameter, which is a positive number; k r is a set control parameter, which is a positive number; u d represents the speed of the desired path tracking; Time first derivative of the reference heading.

[0010] For ASV, system uncertainty and external disturbances can cause frequent chattering of the closed-loop system. This will increase the transmission frequency of the control input and accelerate the wear of the actuator. Considering this limitation, an event trigger mechanism is constructed for the control input. The trigger control input can be described as formula (5).

[0011] (5); in, ω ( t k )express t k Trigger control input at the moment; υ represents the actual control input; n Indicates the host speed; δ Represents the rudder angle.

[0012] The event triggering rules are: ;in, t Indicates the trigger time; t k Indicates k Trigger time; t k+1 Indicates the next adjacent trigger time; k is a positive integer; ω Indicates trigger control input; e ω Indicates the difference between the trigger control input and the actual control input; , ; Indicates that when the trigger time is met Update to the next moment, that is, from t k Updated to t k+1 .

[0013] Accordingly, we can obtain formula (6).

[0014] (6); among which, is a positive number and a constant.

[0015] The nonlinear terms of the model can be approximated by a neural network, and the actuator gain can be learned online by constructing gain adaptive parameters. The event-triggered control law of ASV is shown in Equation (7), and the adaptive law is shown in Equation (8).

[0016] (7); in, n ω Indicates the trigger value of the host speed; ω n An intermediate control variable representing the main engine speed; α n Indicates control; δ W Indicates the rudder angle trigger value; ω δ represents the intermediate control variable of the rudder angle; α δ represents the control torque; k n A positive design parameter indicating the main engine speed; u e Indicates speed error; r e Indicates the heading angular velocity error; k δ A positive design parameter representing the rudder angle; S ( v ) represents Gaussian function; Indicates the host gain value; Indicates the servo gain value; Represents the derivative value of the dynamic surface signal on the forward degree of freedom; It represents the derivative value of the dynamic surface signal on the pitching degree of freedom; represents the update law of the neural network weights on the forward degrees of freedom; Represents the neural network weight update law on the yaw degree of freedom.

[0017] (8); in, express The derivative value of Indicates the positive design parameter on the pitching degree of freedom; Indicates the positive anti-drift parameter on the yaw degree of freedom; express The initial value of express The derivative value of represents a positive design parameter on the forward degree of freedom; represents a positive anti-drift parameter on the forward degree of freedom; express The initial value of .

[0018] At present, the guidance algorithm based on LOS will overshoot at the waypoint. The virtual guidance algorithm needs to rely on time solution, which limits the track tracking task and belongs to the category of track tracking. In the control algorithm, the event triggering technology will reduce the control accuracy while reducing the signal transmission frequency. In the prior art, the quantitative constraint problem of control accuracy under the event triggering technology is not considered. Accordingly, the existing ship track tracking control algorithm has the following two defects: First, the guidance strategy of the existing LOS and its improved method has the problem of steering overshoot at the waypoint. In addition, the virtual ship type in the virtual guidance technology needs to solve the expected path information in real time, which needs to be based on time information. Therefore, it is necessary to specify the thrust command design for the forward degree of freedom, which does not meet the requirements of the ship's ocean navigation track; Second, in the existing track tracking control algorithm, the event triggering technology will reduce the control accuracy, and the quantitative constraint problem of control accuracy under the event triggering technology is not considered. Although the preset performance technology is widely used in control engineering, there is a restriction that the initial state must meet the preset conditions. For ships, the relative error between the initial state and the expected route is difficult to guarantee.

[0019] Therefore, an optimized ship track tracking control method is needed. Summary of the invention

[0020] One advantage of the present application is that it provides a ship track tracking control method based on waypoint routes, wherein the ship track tracking control method based on waypoint routes proposes a hybrid guidance mechanism based on adaptive forward line of sight and virtual lateral adjustment, and sets the guidance switching point according to the maneuverability of the ship to achieve adaptive compensation for the deflection effect caused by external interference factors, thereby solving the problem of overshoot of ship waypoint steering.

[0021] Another advantage of the present application is that it provides a ship track tracking control method based on waypoint routes, wherein the ship track tracking control method based on waypoint routes designs a robust track tracking control mechanism based on preset performance, and introduces an intervention function to solve the semi-global limitation problem of the initial state existing in the preset performance technology, that is, the initial state in the preset performance control needs to be set within the preset limit.

[0022] One advantage of the present application is that it provides a ship track tracking control method based on waypoint routes, wherein the ship track tracking control method based on waypoint routes uses zero-order holder trigger parameters to couple preset performance indicators, which greatly reduces the transmission frequency of control commands; at the same time, the trigger rules are designed according to the control performance indicators, which is more in line with the practice of ship ocean navigation.

[0023] According to one aspect of the present application, a ship track tracking control method based on waypoint routes is provided, which comprises the steps of: Set waypoints and switching points near waypoints; Determine whether the ship meets the guidance switching condition, wherein when the ship meets the guidance switching condition, start the virtual lateral adjustment guidance law; when the ship does not meet the guidance switching condition, start the adaptive line of sight guidance law; Set up track tracking controllers and preset performance targets; and Controlling the vessel to track the desired path based on a track tracking controller and preset performance indicators; Among them, the guidance switching condition is ,in, represents the distance between the next waypoint on the desired path and the previous waypoint on the desired path; S x It represents the equal distance of advance of the ship on the expected path; H Indicates the distance between the previous switching point and the next waypoint; The virtual lateral adjustment guidance law is: ; ѱ 1 represents the expected ship heading angle when the virtual lateral adjustment guidance law is activated; represents the time first-order derivative of the ship heading angle expected when the virtual lateral adjustment guidance law is activated;u Indicates the vertical speed; L 1 represents the length of the line segment between the previous switch point of the next waypoint and the next switch point of the next waypoint; represents half of the angle between the line connecting the previous switching point of the next waypoint of the virtual ship and the next switching point of the next waypoint; The adaptive line-of-sight guidance law is: ;in, ѱ ALOS represents the desired ship heading angle when the adaptive line-of-sight guidance law is activated; ѱ d represents the desired path heading; s y Indicates the lateral offset distance of the ship; Represents the forward line of sight, which is an artificially set constant and is a positive number; Indicates the adaptive value of the wind flow-induced deflection angle.

[0024] In one embodiment of the ship track tracking control method based on waypoint routes described in the present application, ;in, x i-1 Indicates the horizontal coordinate value of the previous waypoint on the desired path; y i-1 Indicates the ordinate value of the previous waypoint on the desired path; x i Indicates the horizontal coordinate value of the next waypoint on the desired path; y i Indicates the ordinate value of the next waypoint on the desired path; Calculated s x and s y ;in, Z i-1 Indicates the distance from the ship to the previous waypoint on the desired path; Z i Indicates the distance from the ship to the next waypoint on the desired path; ;in It represents the time first derivative of the wind flow-induced deflection angle; Indicates the adaptive gain coefficient. Indicates the set adaptive gain coefficient.

[0025] In one embodiment of the ship track tracking control method based on waypoint routes described in the present application, in the process of setting the track tracking controller and presetting the performance index, the track tracking controller is designed and a zero-order holder mechanism is introduced; in the track tracking controller, ; δRepresents the rudder angle; m r represents the additional mass on the pitching degree of freedom; F r represents the servo gain function; k 2 is a design parameter and is a positive number; r e represents the virtual control error; S ( η ) represents the radial basis Gaussian function; W represents the neural network weight matrix; represents the estimated value of the neural network weight matrix; the zero-order holder mechanism is expressed as: ; t Indicates the trigger time; t k Indicates the current trigger time; t k+1 Indicates the next adjacent trigger time; k is a positive integer; δ ( t ) represents the function of the rudder angle with respect to time; δ k ( t k ) represents the trigger value of the current trigger time; the trigger rules are: ;in, ѱ e Indicates the real-time heading error; ρ ( t ) represents a preset performance function; is a constant and a positive number; Represents the trigger threshold parameter, which is an infinitesimal and positive number.

[0026] In one embodiment of the ship track tracking control method based on waypoint routes described in the present application, ;in, Represents the time first derivative of the estimated value of the neural network weight matrix; σ 1 is the first adaptive design parameter and is a positive number; σ 2 is the first adaptive design parameter and is a positive number; W (0) represents the initial value of the neural network weight matrix.

[0027] In one embodiment of the ship track tracking control method based on waypoint routes according to the present application, in the process of setting the track tracking controller and the preset performance index, the preset performance function is used to quantitatively constrain the real-time heading error, wherein the constraint condition is: ;in, ; ρ 0 indicates the preset performance initial value; ρ end Indicates the preset performance stability value; t Indicates time; t 0 represents the initial time; t end represents the steady-state moment; γ represents the preset convergence coefficient; where, ρ 0> ρ end > γ .

[0028] In one embodiment of the ship track tracking control method based on waypoint routes according to the present application, according to the ship track tracking control method based on waypoint routes according to claim 5, ;in, r represents the yaw angular velocity; α 1 indicates virtual control law; , ѱ Indicates the ship's pitch angle; ѱ r Indicates the desired heading angle of the ship.

[0029] In one embodiment of the ship track tracking control method based on waypoint routes described in the present application, the virtual control law is expressed as: ;in, k 1 is a design parameter and is a positive number; β Represents the output error; represents the intervention function; represents the time first-order derivative of the desired ship heading angle; the output error is expressed as: ;in, The intervention value representing the real-time heading error.

[0030] In one embodiment of the ship track tracking control method based on waypoint routes described in the present application, ,in, b represents the intervention coefficient; .

[0031] In one embodiment of the ship track tracking control method based on waypoint routes described in the present application, ;in, represents the time first-order derivative of the virtual control error; d wr Indicates the disturbance force of the external environment on the yaw freedom; f r ( η ) represents the bow nonlinear term that couples the ship’s surge velocity, sway velocity and pitch angular velocity; represents the time first-order derivative of the virtual control law; in the process of setting the track tracking controller and presetting the performance index, the nonlinear terms in the mathematical model of the underactuated ship motion are approximated online, and the approximation method is expressed as: ;in, ε ( η ) represents the approximation error.

[0032] In one embodiment of the ship track tracking control method based on waypoint routes described in the present application, the mathematical model of the ship bow pitch motion is: ;in, ѱ Indicates the ship's pitch angle; It represents the time first-order derivative of the ship's pitch angle; r represents the yaw angular velocity; It represents the time first-order derivative of the yaw angular velocity; m r represents the additional mass on the pitching degree of freedom; d wr Indicates the disturbance force of the external environment on the yaw freedom; F r represents the servo gain function; f r ( η ) represents the bow nonlinear term that couples the ship’s surge velocity, sway velocity and pitch angular velocity; δ Represents the rudder angle; ; x Indicates the abscissa value of the ship; y Indicates the vertical coordinate value of the ship; ѱ represents the ship's pitch angle; (x, y, Ψ) represents the ship's position coordinates and pitch angle.

[0033] Further objectives and advantages of the present application will be fully reflected through understanding of the following description and drawings.

[0034] These and other objects, features and advantages of the present application are fully reflected in the following detailed description, drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the drawings, the same reference numerals generally represent the same components.

[0036] Figure 1The figure illustrates a schematic diagram of the guidance principle of a ship track tracking control method based on waypoint routes according to an embodiment of the present application.

[0037] Figure 2 The figure illustrates a flowchart schematic diagram of a ship track tracking control method based on waypoint routes according to an embodiment of the present application.

[0038] Figure 3 A flowchart schematic diagram of a specific example of a ship track tracking control method based on a waypoint route according to an embodiment of the present application is illustrated.

[0039] Figure 4 The figure shows a schematic diagram comparing the heading tracking results of the ship track tracking control method based on waypoint routes according to an embodiment of the present application and the prior art under simulation conditions.

[0040] Figure 5 The figure shows a schematic diagram of a partial comparison of the heading tracking results of the ship track tracking control method based on waypoint routes according to an embodiment of the present application and the prior art under simulation conditions.

[0041] Figure 6 The figure shows a schematic diagram of the error evolution curve comparison between the ship track tracking control method based on waypoint routes according to an embodiment of the present application and the prior art under simulation conditions.

[0042] Figure 7 The figure shows a schematic diagram of a partial comparison of the error evolution curve of the ship track tracking control method based on waypoint routes according to an embodiment of the present application and the prior art under simulation conditions.

[0043] Figure 8 The figure shows a schematic diagram of a comparison between the ship track tracking control method based on waypoint routes according to an embodiment of the present application and the control command curve of the prior art under simulation conditions.

[0044] Fig. 9 The figure shows a schematic diagram of a partial comparison of the control command curve of the ship track tracking control method based on waypoint routes according to an embodiment of the present application and the prior art under simulation conditions.

[0045] Fig.10 The figure illustrates a schematic diagram of an adaptive update curve diagram of a ship track tracking control method based on waypoint routes according to an embodiment of the present application under simulation conditions.

[0046] Fig.11 A schematic diagram of a ship track tracking trajectory curve diagram of a ship track tracking control method based on a waypoint route according to an embodiment of the present application under simulation conditions is shown.

[0047] Fig.12The figure illustrates a schematic diagram of a local ship track tracking trajectory curve diagram of a ship track tracking control method based on waypoint routes according to an embodiment of the present application under simulation conditions.

[0048] Fig.13 The figure shows a schematic diagram of a ship heading error curve diagram according to the ship track tracking control method based on waypoint routes according to an embodiment of the present application under simulation conditions. DETAILED DESCRIPTION

[0049] Below, the exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the exemplary embodiments described here.

[0050] It is understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "one" cannot be understood as a limitation on the number. "Multiple" means greater than or equal to two.

[0051] Although ordinals such as "first," "second," and the like will be used to describe various components, those components are not limited herein. The term is used only to distinguish one component from another. For example, a first component may be referred to as a second component, and likewise, a second component may be referred to as a first component without departing from the teachings of the present application. The term "and / or" as used herein includes any and all combinations of one or more associated listed items.

[0052] The terms used herein are only used for the purpose of describing various embodiments and are not intended to be limiting. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates an exception. It will also be understood that the terms "including" and / or "having" when used in this specification specify the presence of the described features, numbers, operations, components, elements, or combinations thereof, without excluding the presence or addition of one or more other features, numbers, operations, components, elements, or combinations thereof.

[0053] Glossary Surge: The translational movement of a ship in the forward (bow) and aft (stern) directions.

[0054] Sway: The translation of a ship to the left (port side) or right (starboard side).

[0055] Yaw pitch: The left-right swaying of the bow of a ship.

[0056] Surge speed: the translational speed of a ship in the fore-and-aft direction.

[0057] Sway speed: the translation speed of the ship in the left and right directions.

[0058] Yaw speed: the angular velocity of the ship in the left and right directions.

[0059] Schematic diagram of ship track tracking control method based on waypoint route like Figures 2 to 13 As shown, the ship track tracking control method based on the waypoint route according to the embodiment of the present application is explained. Figures 1 to 3 As shown, the ship track tracking control method based on waypoint routes proposed in this application proposes a hybrid guidance mechanism based on adaptive forward line of sight and virtual lateral adjustment. The guidance switching point is set according to the maneuverability of the ship to achieve adaptive compensation for the deflection caused by external interference factors, and solve the problem of overshoot of ship waypoint steering. Specifically, when the ship has not reached the switching point, the adaptive line of sight guidance law with the introduction of adaptive terms is executed, which can reduce the deflection effect of external interference such as wind flow on the ship; when the ship is between the switching points, the virtual lateral adjustment guidance law is executed, which can turn in a circular path to avoid overshoot of the ship waypoint steering.

[0060] Accordingly, if Figure 2 As shown, the ship track tracking control method based on waypoint routes according to an embodiment of the present application includes the steps of: S110, setting waypoints and switching points near waypoints; S120, judging whether the ship meets the guidance switching conditions, wherein when the ship meets the guidance switching conditions, starting the virtual lateral adjustment guidance law; when the ship does not meet the guidance switching conditions, starting the adaptive line of sight guidance law; S130, setting a track tracking controller and preset performance indicators in response to the real-time heading error satisfying the self-adjustment trigger rule, updating the trigger heading error in the self-adjustment trigger rule to form an updated self-adjustment trigger rule; and, S140, controlling the ship to track the desired path based on the track tracking controller and the preset performance indicators.

[0061] Before step S110, an underactuated ship model needs to be established. In the embodiment of the present application, the underactuated ship model is a 3-degree-of-freedom nonlinear mathematical model, which is expressed as: ;in, ; x Indicates the abscissa value of the ship; y Indicates the vertical coordinate value of the ship; ѱ Indicates the ship's pitch angle; [ x , y , Ψ ] is used to indicate the position coordinates and heading angle of the ship; express The transposed matrix of express The time first derivative of ; , J ( ѱ ) is the ship position transformation matrix; ;in, u Indicates the vertical speed; v Indicates the sway velocity; r represents the yaw angular velocity; u , v , r ] is used to indicate the ship's longitudinal speed, transverse speed, and bow angular velocity; express[ u , v , r ] is the transposed matrix; express N The time first derivative of ; M represents the additional mass matrix of the ship; ; d wu It indicates the interference force on the longitudinal freedom degree of the external environment; d wv It represents the disturbance force on the lateral freedom degree of the external environment; d wr Indicates the disturbance force of the external environment on the yaw freedom; Indicates the interference force of the external environment; express The transposed matrix of ; Indicates the propulsion force of the ship; represents the turning moment; n Indicates the host speed; δ Represents the rudder angle; ; F r Represents the servo gain function.

[0062] For track tracking control tasks, the main engine is usually selected to sail at a constant speed, that is, the main engine speed of the ship model is not selected. n Expand the controller design and carry out the control algorithm design only for the ship's bow degree of freedom. Therefore, the ship mathematical model used for track tracking controller design can be simplified as follows: ;in, It represents the time first-order derivative of the ship's pitch angle, that is, the pitch angular velocity; It represents the time first-order derivative of the yaw angular velocity; m r represents the additional mass on the yaw degree of freedom; f r ( η ) represents the bow nonlinear term that couples the ship’s surge velocity, sway velocity and bow angular velocity.

[0063] After establishing the underactuated ship model, a guidance law is established. For the track tracking control task based on waypoints, the guidance algorithm can solve the bow reference signal for the control system. In order to solve the overshoot problem caused by the LOS guidance algorithm and the time dependence problem of the virtual guidance technology, the present application proposes a hybrid guidance law based on adaptive line-of-sight guidance law (ALOS) and virtual lateral adjustment. The guidance switching point is set according to the maneuverability of the ship to achieve adaptive compensation for the deflection caused by external interference factors. Specifically, when the ship has not reached the switching point, the adaptive line-of-sight guidance law with the introduction of adaptive terms is executed, which can reduce the deflection effect of external interference such as wind flow on the ship; when the ship is between the switching points, the virtual lateral adjustment guidance law is executed, which can turn in a circular path to avoid overshoot of the ship's waypoint steering.

[0064] Accordingly, in the guidance process, the waypoint and the switching point are first set. Accordingly, in step S110, the waypoint and the switching point near the waypoint are set. Specifically, the coordinates of the waypoint are given by W 1( x 1, y 1), W 2( x 2, y 2), …, W i-1 ( x i-1 , y i-1 ), W i ( x i , y i ) is generated. Figure 1 As shown, W i-1 Indicates the previous waypoint relative to the vessel's current position; W i Indicates the next waypoint relative to the vessel's current position. ( x i-1 , y i-1 ) are the coordinates of the previous waypoint relative to the current position of the vessel, i.e., the coordinates of the previous waypoint on the desired path; ( x i , y i ) are the coordinates of the next waypoint relative to the current position of the ship, i.e., the coordinates of the next waypoint on the desired path. Accordingly, x i-1 Indicates the horizontal coordinate value of the previous waypoint on the desired path;y i-1 Indicates the ordinate value of the previous waypoint on the desired path; x i Indicates the horizontal coordinate value of the next waypoint on the desired path; y i Indicates the ordinate value of the next waypoint on the desired path.

[0065] The coordinates of the switching point are set near the waypoint, where Figure 1 As shown, s i-1 Indicates the next waypoint W i The previous switching point; s i Indicates the next waypoint W i The next switching point. s x It represents the equal distance of advance of the ship on the route, where the equal distance of advance of the ship on the route is equal to the difference between the orthographic projection of the ship on the expected path and the previous waypoint W i-1 The distance between. s y represents the lateral offset distance of the ship, where the lateral offset distance of the ship is equal to the distance between the ship's orthographic projection on the desired path and the ship.

[0066] After setting the waypoints and switching points, the ship track tracking loop is entered. The ship track tracking loop includes the guidance law selection and track tracking control design loop based on the judgment of whether the ship meets the guidance switching conditions.

[0067] In the embodiment of the present application, when the ship has not reached the switching point, the adaptive line of sight guidance law is executed; when the ship reaches the switching point, the virtual lateral adjustment guidance law is executed. Accordingly, in step S120, it is determined whether the ship meets the guidance switching condition. When the ship meets the guidance switching condition, it is determined that the ship has reached the switching point and the virtual lateral adjustment guidance law is started; when the ship does not meet the guidance switching condition, it is determined that the ship has not reached the switching point and the adaptive line of sight guidance law is started. The guidance switching condition is , H Indicates the distance from the previous switch point to the next waypoint.

[0068] Accordingly, when the ship does not reach the switching point, that is, the corresponding expected path segment is the previous waypoint on the expected path W i-1 ( x i-1 , y i-1) and the previous switching point of the next waypoint on the desired path s i-1 When the flight segments are between , the desired ship heading angle can be obtained by the adaptive line-of-sight guidance law To calculate; among them, ѱ ALOS represents the desired ship heading angle when the adaptive line-of-sight guidance law is activated; ѱ d represents the desired path heading; s y Indicates the lateral offset distance of the ship; It represents the forward sight distance, which is expressed as the distance between the ship's orthographic projection on the desired path and the ship's virtual intersection point. The ship's virtual intersection point refers to the intersection point of the line of sight corresponding to the desired ship heading angle when the adaptive line of sight guidance law is started and the desired path. It is an artificially set constant and is a positive number. Indicates the adaptive value of the wind flow-induced deflection angle.

[0069] pass Calculate the desired path heading, where: ѱ d Indicates the desired path heading. Calculated s x and s y ;in, Z i-1 Indicates the distance from the ship to the previous waypoint on the desired path, which can be obtained from the ship's real-time coordinates ( x , y ) and the coordinates of the previous waypoint on the desired path ( x i-1 , y i-1 )get; Z i Indicates the distance from the ship to the next waypoint on the desired path, which can be obtained from the ship's real-time coordinates ( x , y ) and the coordinates of the next waypoint on the desired path ( x i , y i )get; The distance between the next waypoint on the desired path and the previous waypoint on the desired path can be obtained by the coordinates of the previous waypoint on the desired path ( x i-1 , y i-1 ) and the coordinates of the next waypoint on the desired path ( xi , y i )get.

[0070] ;in The time first derivative of the adaptive value of the wind flow-induced deflection angle; Indicates the adaptive gain coefficient. Indicates the set adaptive gain coefficient.

[0071] When , it means that the ship reaches the switching point. In order to avoid the ship from oversteering, the present application constructs a virtual lateral adjustment guidance law.

[0072] Specifically, the virtual lateral adjustment guidance law is: ; ѱ 1 represents the expected ship heading angle when the virtual lateral adjustment guidance law is activated; represents the time first-order derivative of the ship heading angle expected when the virtual lateral adjustment guidance law is activated; u Indicates the vertical speed; L 1 represents the length of the line segment between the previous switch point of the next waypoint and the next switch point of the next waypoint; Represents half of the angle between the line before the switching point of the next waypoint of the virtual ship and the next switching point of the next waypoint.

[0073] Accordingly, the hybrid guidance law of the present application is: ; ѱ r Indicates the desired heading angle of the ship, i.e., the reference heading.

[0074] After establishing the guidance algorithm, the track tracking control design loop is started, and the control part is established to control the ship to track the desired path. Specifically, the present application proposes a robust track tracking control algorithm based on preset performance. Accordingly, the track tracking control design loop includes setting a track tracking controller and a preset performance index and controlling the ship to track the reference path based on the track tracking controller and the preset performance index. In step S130, the track tracking controller and the preset performance index are set.

[0075] Specifically, in the process of setting the track tracking controller and the preset performance index, the preset performance function is used to quantitatively constrain the real-time heading error, wherein the constraint condition is: ;in, is a constant and a positive number; ѱ e Indicates the real-time heading error; ρ ( t ) represents a preset performance function.

[0076] , ѱ Indicates the ship's pitch angle; ѱ r Indicates the expected heading angle of the ship; real-time heading error ѱ e Equal to the difference between the ship's current heading and the desired ship heading angle. ; t Indicates time; t 0 represents the initial time, which is the start time of system operation; t end represents the steady-state moment, the time when the system reaches a stable state; γ Indicates the preset convergence coefficient; ρ 0 indicates the preset performance initial value, that is, t The preset performance value at time 0; ρ end Indicates the preset performance stability value, that is, t end The preset performance value at the moment; where, ρ 0> ρ end > γ .

[0077] Furthermore, the present application introduces an intervention function to solve the semi-global limitation problem of the initial state in the preset performance technology, that is, the limitation problem that the initial state in the preset performance control needs to be set within the preset limit. Accordingly, in the process of setting the track tracking controller and the preset performance index, in order to ensure that the real-time heading error is within the preset limit in the initial stage, the present application defines an intervention function, wherein the intervention function is: ,in, b represents the intervention coefficient.

[0078] Accordingly, the real-time heading error ѱ e The intervention value can be written as: ;in, Indicates the intervention value of the real-time heading error.

[0079] Furthermore, in the process of setting the track tracking controller and presetting the performance index, an output error based on the intervention function is defined. Specifically, the output error is expressed as: ;in, β Represents the output error.

[0080] To stabilize the output error β , a virtual control law is designed. Accordingly, in the process of setting the track tracking controller and presetting the performance index, the virtual control law is set. Specifically, the virtual control law is expressed as ;in, α 1 indicates virtual control law; k 1 is a design parameter and is a positive number.

[0081] Definition In the process of setting the track tracking controller and presetting the performance index, a virtual control error is defined. Specifically, the virtual control error is expressed as: ;in, r e represents the virtual control error; r represents the virtual control error of the yaw angular velocity; r e It is equal to the difference between the bow angular velocity and the virtual control law.

[0082] The derivative of the virtual control error can be obtained: ;in, represents the time first-order derivative of the virtual control error; Represents the time first-order derivative of the virtual control law.

[0083] The present application adopts neural network technology to perform online approximation on the nonlinear terms of the model, avoiding the problem of using dynamic surface control technology to derive the virtual control law in the prior art. Specifically, a radial basis function neural network (RBFNN) can be used to perform online approximation on the nonlinear terms in the control system.

[0084] Accordingly, in the process of setting the track tracking controller and presetting the performance indicators, the nonlinear terms in the mathematical model of the underactuated ship motion are approximated online, avoiding the problem of deriving the virtual control law using dynamic surface control technology in the prior art.

[0085] Specifically, the approximation is expressed as: ;in, W represents the neural network weight matrix; S ( η ) represents the radial basis Gaussian function; ε ( η ) represents the approximation error.

[0086] Accordingly, a trajectory tracking controller is designed. In the trajectory tracking controller, ; Represents the estimated value of the neural network weight matrix; k 2 is a design parameter and is a positive number.

[0087] ;in, Represents the time first derivative of the estimated value of the neural network weight matrix; σ1 is the first adaptive design parameter and is a positive number; σ 2 is the first adaptive design parameter and is a positive number; W (0) represents the initial value of the neural network weight matrix.

[0088] Considering the rudder angle δ Real-time solution and transmission to the steering gear control system will cause frequent execution of the steering gear and increase wear. Therefore, this application introduces a zero-order holder mechanism to trigger the parameters and couple the preset performance indicators to minimize the transmission frequency of the control command; at the same time, the trigger rules are designed according to the control performance indicators, which is more in line with the practice of ship ocean navigation.

[0089] Accordingly, in the process of setting the track tracking controller and presetting the performance index, the zero-order holder mechanism is introduced, where the zero-order holder mechanism is expressed as: ; t Indicates the trigger time; t k Indicates the current trigger time; t k+1 Indicates the next adjacent trigger time; k is a positive integer; δ ( t ) represents the function of the rudder angle with respect to time; δ k ( t k ) represents the trigger value of the current trigger time, that is, the rudder angle at the current trigger time.

[0090] The triggering rules are: ;in, Represents the trigger threshold parameter, which is an infinitesimal and positive number. Indicates that when the trigger time is met Update to the next trigger time, that is, from t k Updated to t k+1 .

[0091] In step S140, the ship is controlled to track the desired path based on the track tracking controller and the preset performance index. Specifically, when the trigger rule is met, the trigger value of the current trigger time, that is, the rudder angle of the current trigger time, is updated to the trigger value of the next adjacent trigger time, that is, the rudder angle of the next adjacent trigger time. The trigger value represents the next adjacent trigger time, and then controls the ship to track the desired path, that is, the reference path; and restarts the track tracking control design loop, sets the intervention value and output error of the real-time heading error, sets the virtual control law, uses the neural network technology to approximate the nonlinear terms of the model online, and determines whether the trigger conditions are met through the zero-order holder mechanism. When the trigger rule is not met, the rudder angle is still equal to the trigger value of the current trigger time, and controls the ship to track the desired path. Accordingly, the track tracking control design loop includes: setting the intervention value and output error of the real-time heading error, setting the virtual control law, using the neural network technology to approximate the nonlinear terms of the model online, and determining whether the trigger conditions are met through the zero-order holder mechanism, and controlling the ship to track the desired path based on the track tracking controller and the preset performance indicators.

[0092] When the controlled ship completes the path tracking task, the tracking ends. When the controlled ship fails to complete the path tracking task, the ship re-enters the ship's inter-vehicle tracking loop. First, the guidance law is selected based on the judgment of whether the ship meets the guidance switching conditions. Then the track tracking control loop is designed, the intervention value and output error of the real-time heading error are set, the virtual control law is set, and the neural network technology is used to approximate the nonlinear terms of the model online. The zero-order holder mechanism is used to judge whether the trigger conditions are met. Based on the track tracking controller and the preset performance indicators, the ship is controlled to track the expected path until the path tracking task is completed.

[0093] In order to verify the effectiveness of the ship track tracking control method based on waypoint routes in the embodiment of the present application, a computer simulation experiment was conducted using Matrix&laboratory (matlab) software and compared with the prior art. The desired ship heading angle was set to 30 degrees. Figures 4 to 9 A comparison diagram of the ship track tracking control method based on waypoint routes according to the embodiment of the present application and the prior art is shown in a simulation. In the diagram, the ship track tracking control method based on waypoint routes according to the embodiment of the present application is represented by "the algorithm of this paper"; the prior art is represented by "algorithm A". Figure 4 and Figure 5 It can be seen that both the "algorithm of this paper" and "algorithm A" can effectively achieve good tracking performance. However, although "algorithm A" shows advantages in response time, it is accompanied by the emergence of overshoot, which makes the ship's heading angle exceed 30 degrees. Figure 6 to Figure 7 It is clearly shown that the heading error used in the control design of the "algorithm in this paper" is small. Specifically, the intervention function based on the preset performance makes the control input required in the initial stage lower, so that the heading error used in the control design of the "algorithm in this paper" is small. In addition, Figures 8 to 10It can also be seen that the control command of the "algorithm in this paper" has lower jitter performance. The lower jitter performance of the control command has a significant effect on energy saving, which is mainly attributed to the online approximation of the model uncertainty and external disturbance by the radial basis function neural network. Accordingly, Fig.10 The adaptive update curve diagram of the learning parameters of the ship track tracking control method based on the waypoint route according to the embodiment of the present application is shown in a simulation situation. Fig.10 middle Represents the norm of the estimate of the neural network weight matrix.

[0094] The present application embodiment conducted a track tracking experiment. In the track tracking experiment, 4 waypoints were set, and the 4 waypoints were: W 1(0, 0), W 2(300, 400), W 3(800, 400), W i (1100, 0), the horizontal and vertical coordinates of each waypoint are in meters. Figures 11 to 13 The results of trajectory tracking experiments are shown. Figure 6 and Figure 7 The ship's track tracking curve is shown. Figure 6 It can be seen that the ship travels along the waypoint track line, and the ship track tracking control method based on the waypoint route according to the embodiment of the present application can effectively track the track line. In particular, at the waypoint turning point, the ship can achieve steering control in a relatively gentle path through the guidance of the virtual lateral adjustment signal, such as Figure 7 As shown, overshoot is avoided at the same time. Figure 8 The real-time heading error and the intervention value of the real-time heading error are displayed; the intervention value of the real-time heading error is the error after the real-time heading error is intervened in the initial stage to form a preset boundary, which helps to avoid the singularity problem caused by the real-time heading error exceeding the preset limit in the initial stage.

[0095] Combined with the above verification experiments, the ship track tracking control method based on waypoint routes in the embodiment of the present application solves the defect that the traditional heading keeping control algorithm cannot simulate the ship duty officer's steering habit to update the rudder order, and can realize the ship to autonomously determine the timing of steering according to the heading situation, which is of great significance to the intelligent driving of large ships. It also makes all signals transmitted and calculated only at the trigger time, which greatly reduces the computing load and saves communication resources.

[0096] The present application and its implementation methods are described above, and such description is not restrictive. The drawings show only one implementation method of the present application, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design structural methods and embodiments similar to the technical solution without creative design without departing from the inventive purpose of the present application, they should all fall within the protection scope of the present application.

Claims

1. A ship track tracking control method based on waypoint routes, characterized in that: Includes steps: Set waypoints and switching points near waypoints; Determine whether the ship meets the guidance switching condition, wherein when the ship meets the guidance switching condition, start the virtual lateral adjustment guidance law; when the ship does not meet the guidance switching condition, start the adaptive line of sight guidance law; Set up track tracking controllers and preset performance targets; and Controlling the vessel to track the desired path based on a track tracking controller and preset performance indicators; Among them, the guidance switching condition is ,in, represents the distance between the next waypoint on the desired path and the previous waypoint on the desired path; S x It represents the equal distance of advance of the ship on the expected path; H Indicates the distance between the previous switching point and the next waypoint; The virtual lateral adjustment guidance law is: ; ѱ 1 represents the expected ship heading angle when the virtual lateral adjustment guidance law is activated; represents the time first-order derivative of the ship heading angle expected when the virtual lateral adjustment guidance law is activated; u Indicates the vertical speed; L 1 represents the length of the line segment between the previous switch point of the next waypoint and the next switch point of the next waypoint; represents half of the angle between the line connecting the previous switching point of the next waypoint of the virtual ship and the next switching point of the next waypoint; The adaptive line-of-sight guidance law is: ;in, ѱ ALOS represents the desired ship heading angle when the adaptive line-of-sight guidance law is activated; ѱ d represents the desired path heading; s y Indicates the lateral offset distance of the ship; Represents the forward line of sight, which is an artificially set constant and is a positive number; Indicates the adaptive value of the wind flow-induced deflection angle.

2. The ship track tracking control method based on waypoint route according to claim 1, wherein: ； in, x i-1 Indicates the horizontal coordinate value of the previous waypoint on the desired path; y i-1 Indicates the ordinate value of the previous waypoint on the desired path; x i Indicates the horizontal coordinate value of the next waypoint on the desired path; y i Indicates the ordinate value of the next waypoint on the desired path; Calculated s x and s y ;in, Z i-1 Indicates the distance from the ship to the previous waypoint on the desired path; Z i Indicates the distance from the ship to the next waypoint on the desired path; ;in The time first derivative of the adaptive value of the wind flow-induced deflection angle; Indicates the adaptive gain coefficient. Indicates the set adaptive gain coefficient.

3. The ship track tracking control method based on waypoint route according to claim 2, wherein: In the process of setting the track tracking controller and presetting the performance indicators, the track tracking controller is designed and the zero-order holder mechanism is introduced; In the track tracking controller, ; δ Represents the rudder angle; m r represents the additional mass on the pitching degree of freedom; F r represents the servo gain function; k 2 is a design parameter and is a positive number; r e represents the virtual control error; S ( η ) represents the radial basis Gaussian function; W represents the neural network weight matrix; Represents the estimated value of the neural network weight matrix; The zero-order holder mechanism is expressed as: ; t Indicates the trigger time; t k Indicates the current trigger time; t k+1 Indicates the next adjacent trigger time; k is a positive integer; δ ( t ) represents the function of the rudder angle with respect to time; δ k ( t k ) represents the trigger value of the current trigger time; the trigger rules are: ;in, ѱ e Indicates the real-time heading error; ρ ( t ) represents a preset performance function; is a constant and a positive number; Represents the trigger threshold parameter, which is an infinitesimal and positive number.

4. The ship track tracking control method based on waypoint route according to claim 3, wherein: ;in, Represents the time first derivative of the estimated value of the neural network weight matrix; σ 1 is the first adaptive design parameter and is a positive number; σ 2 is the first adaptive design parameter and is a positive number; W (0) represents the initial value of the neural network weight matrix.

5. The ship track tracking control method based on waypoint route according to claim 3, wherein: In the process of setting the track tracking controller and presetting the performance index, the preset performance function is used to quantitatively constrain the real-time heading error, where the constraint condition is: ;in, ; ρ 0 indicates the preset performance initial value; ρ end Indicates the preset performance stability value; t Indicates time; t 0 represents the initial time; t end represents the steady-state moment; γ represents the preset convergence coefficient; where, ρ 0> ρ end > γ .

6. The ship track tracking control method based on waypoint route according to claim 5, wherein: ;in, r represents the yaw angular velocity; α 1 indicates virtual control law; , ѱ Indicates the ship's pitch angle; ѱ r Indicates the desired heading angle of the ship.

7. The ship track tracking control method based on waypoint route according to claim 6, wherein: The virtual control law is expressed as: ;in, k 1 is a design parameter and is a positive number; β Represents the output error; represents the intervention function; represents the time first-order derivative of the desired ship heading angle; the output error is expressed as: ;in, The intervention value representing the real-time heading error.

8. The ship track tracking control method based on waypoint route according to claim 7, wherein: ,in, b represents the intervention coefficient; .

9. The ship track tracking control method based on waypoint route according to claim 8, wherein: ;in, represents the time first-order derivative of the virtual control error; d wr Indicates the disturbance force of the external environment on the yaw freedom; f r ( η ) represents the bow nonlinear term that couples the ship’s surge velocity, sway velocity and pitch angular velocity; represents the time first-order derivative of the virtual control law; in the process of setting the track tracking controller and presetting the performance index, the nonlinear terms in the mathematical model of the underactuated ship motion are approximated online, and the approximation method is expressed as: ;in, ε ( η ) represents the approximation error.

10. The ship track tracking control method based on waypoint route according to claim 1, wherein: The mathematical model of ship bow rolling motion is: ； in, ѱ Indicates the ship's pitch angle; It represents the time first-order derivative of the ship's pitch angle; r represents the yaw angular velocity; It represents the time first derivative of the yaw angular velocity; m r represents the additional mass on the pitching degree of freedom; d wr Indicates the disturbance force of the external environment on the yaw freedom; F r represents the servo gain function; f r ( η ) represents the bow nonlinear term that couples the ship’s surge velocity, sway velocity and pitch angular velocity; δ Represents the rudder angle; ; x Indicates the abscissa value of the ship; y Indicates the vertical coordinate value of the ship; ѱ Indicates the ship's pitch angle; x , y , Ψ ) represents the position coordinates and heading angle of the ship.

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