An unmanned boat path following method and system affected by random disturbances

Abstract

The present invention discloses a path following method and system for an unmanned surface vehicle affected by random disturbances, including: randomly modeling the unmanned surface vehicle system considering the random disturbances brought by environmental noise; secondly, setting a desired following path and calculating the tangential and cross following errors of the unmanned surface vehicle relative to the desired following path; then, designing a desired yaw angle, a desired resultant velocity and path variables to make the tangential and cross following errors of the unmanned surface vehicle relative to the desired following path converge; finally, designing a thrust controller and a rudder angle controller to ensure that the resultant velocity and yaw angle of the unmanned surface vehicle track the desired resultant velocity and the desired yaw angle. On the one hand, the present invention can ensure the following performance of the unmanned surface vehicle for the desired following path, and on the other hand, can improve the robustness of the path following algorithm of the unmanned surface vehicle under the condition of random disturbances. Simulations show that the present invention can achieve the path following task of the unmanned surface vehicle under the influence of random disturbances.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned boat path following, and in particular to a method and system for unmanned boat path following affected by random disturbances. Background Art

[0002] Due to the latest advances in sensing, communication, and distributed control technologies, the control applications of unmanned boats have gradually become widespread. As a new type of intelligent surface combat force, unmanned boats have the advantages of low cost and high mobility. They can be used to perform tasks such as reconnaissance patrol, hydrographic exploration, material transportation, and emergency rescue. At the same time, due to their unmanned and intelligent characteristics, they can effectively reduce human consumption and avoid casualties when performing tasks. When unmanned boats perform complex tasks such as patrol, rescue, capture, monitoring, and reconnaissance, they usually first formulate a desired following path and then need to move forward along the specified path. Therefore, path following is a very important research direction for unmanned boats.

[0003] In the prior art, for the situation where unmanned boats face disturbances such as environmental noise, adaptive neural network estimation methods and methods such as setting upper and lower limits of disturbances are usually adopted. However, considering the randomness of environmental noise interference, if a neural network approximation method is used, such as [Chen L, Cui R, Yang C, et al. Adaptive neural network control of underactuated surface vessels with guaranteed transient performance: Theory and experimental results [J]. IEEE Transactions on Industrial Electronics, 2019, 67(5): 4024-4035], it cannot be guaranteed whether the environmental noise interference is defined on a compact set, which is theoretically not rigorous; if the method of setting upper and lower limits of disturbances is used, such as [Cui B, Xia Y, Liu K, et al. Finite-time tracking control for a class of uncertain strict-feedback nonlinear systems with state constraints: A smooth control approach [J]. IEEE Transactions on Neural Networks and Learning Systems, 2020, 31(11): 4920-4932], it will lead to greater conservativeness in analysis and reduce the robustness and control accuracy of the system.

[0004] Therefore, in view of the phenomenon that the current unmanned boat system faces the influence of random disturbances when performing tasks, there is an urgent need for an unmanned boat control system that can achieve efficient control in complex environmental situations. This new type of control system not only needs to ensure the path following accuracy of the unmanned boat under random disturbances, but also needs to ensure the robustness of the control performance, so as to further promote the application of unmanned boats in real task environments. Summary of the Invention

[0005] Object of the Invention: An object of the present invention is to provide a path following method for an unmanned boat affected by random disturbances to ensure the path following accuracy of the unmanned boat and improve the robustness of the unmanned boat system when facing random disturbances.

[0006] Another object of the present invention is to further provide a system corresponding to the method.

[0007] Technical solution: The path following method for an unmanned boat affected by random disturbances according to the present invention includes the following steps:

[0008] Considering the random disturbances brought by environmental noise, perform stochastic modeling on the unmanned boat system;

[0009] Set the desired following path, and calculate the tangential and cross following errors of the unmanned boat relative to the desired following path;

[0010] Design the desired yaw angle, desired resultant velocity and path variables so that the tangential and cross following errors of the unmanned boat relative to the desired following path converge;

[0011] Design a thrust controller and a rudder angle controller to ensure that the resultant velocity and yaw angle of the unmanned boat track the desired resultant velocity and desired yaw angle.

[0012] Furthermore, the model expression of the unmanned boat system under the influence of random disturbances is:

[0013]

[0014] where, is the position and yaw angle of the unmanned boat in the world coordinate system, where (x, y) is the northward and eastward positions of the unmanned boat in the world coordinate system, ψ is the yaw angle of the unmanned boat in the world coordinate system, T is the transpose of a matrix or vector, is the derivative of η, are the forward, lateral and yaw velocities of the unmanned boat in the body coordinate system, is the derivative of ξ, is the vector composed of the thrust controller and the rudder angle controller of the unmanned boat, τ u is the thrust controller, τ r is the rudder angle controller, represents the vector composed of random disturbance coefficients, d1 represents the random disturbance coefficient acting on the forward acceleration of, d2 represents the random disturbance coefficient acting on the lateral acceleration of, d3 represents the random disturbance coefficient acting on the yaw acceleration of, B(t) is white noise, J(ψ), M, C(ξ), D(ξ) are the rotation matrix, mass matrix, Coriolis force matrix and nonlinear damping matrix respectively.

[0015] Furthermore, the desired following path is expressed as (x d , y d ), where x d and y d respectively represent the northward and eastward positions of the desired following path in the world coordinate system, and are functions of θ, and θ is the path variable.

[0016] Further, calculate the tangential and cross following errors of the unmanned boat relative to the desired following path, including:

[0017] (1) Establish a tangent coordinate system with the moving tangent direction of the desired following path as the T-axis and the normal direction as the N-axis, and calculate the angle ψ between the moving tangent direction of the path point and the north direction. d ;

[0018] (2) Convert the position following error of the unmanned boat relative to the desired following path in the world coordinate system to the tangent coordinate system.

[0019] (3) Calculate the derivative of the position error system of the unmanned boat relative to the desired following path in the tangent coordinate system.

[0020] Further, the angle ψ between the moving tangent direction of the path point and the north direction d is calculated by the formula:

[0021] ψ d = atan2(y′ d , x′ d ), ψ d ∈[-π, π]

[0022] where x d ′, y d ′ are the first-order partial derivatives of x d , y d with respect to the path variable θ, x d and y d represent the northward and eastward positions of the desired following path in the world coordinate system respectively, and (x d , y d ) is the desired following path;

[0023] The position error system of the unmanned boat relative to the desired following path in the tangent coordinate system is expressed as:

[0024]

[0025] where x e is the tangential following error of the unmanned boat in the tangent coordinate system, and y e is the cross following error of the unmanned boat in the tangent coordinate system;

[0026] The derivative of the position error system of the unmanned boat relative to the desired following path is:

[0027]

[0028] where, and are the derivatives of x e and y e respectively. is the combined velocity of the unmanned boat, where \(u\) and \(v\) are the forward and lateral velocities of the unmanned boat in the body coordinate system, and \(\psi\) ω \(=\psi+\beta\) is the heading angle of the unmanned boat, \(\psi\) is the yaw angle of the unmanned boat, and \(\beta = \text{atan2}(v, u)\) is the sideslip angle of the unmanned boat, is the derivative of \(\psi\) d , and is the derivative of the path variable \(\theta\).

[0029] Furthermore, design the desired yaw angle, desired combined velocity, and path variable to make the tangential and cross-track following errors of the unmanned boat relative to the desired following path converge, including:

[0030] (1) For the combined velocity \(U\) and yaw angle \(\psi\) of the unmanned boat in the error system, design the desired combined velocity \(U\) c and the desired yaw angle \(\psi\) c :

[0031]

[0032] where \(\psi\) d is the angle between the moving tangent direction of the path point and the north direction, \(y\) e is the cross-track following error of the unmanned boat in the tangent coordinate system, \(d\) is the look-ahead distance, \(\beta = \text{atan2}(v, u)\) is the sideslip angle of the unmanned boat, and \(u\) and \(v\) are the forward and lateral velocities of the unmanned boat in the body coordinate system, \(x\) d \(^\prime\), \(y\) d \(^\prime\) are the first-order partial derivatives of \(x\) d , \(y\) d with respect to the path variable \(\theta\), \((x\) d , \(y\) d ) is the desired following path, \(x\) d and \(y\) d represent the northward and eastward positions of the desired following path in the world coordinate system respectively, \(v\) d is the reference velocity designed for , and is the derivative of the path variable \(\theta\);

[0033] (2) Calculate the derivative of the position error system of the unmanned boat relative to the desired following path based on the desired combined velocity and desired yaw angle;

[0034]

[0035] where and are the derivatives of \(x\) e and \(y\) e respectively, and \(x\) eis the tangential following error of the unmanned boat in the tangent coordinate system, y e is the cross following error of the unmanned boat in the tangent coordinate system, is the derivative of ψ d , α1 = u d v d / d > 0;

[0036] (3) Design the derivative of the path variable θ as:

[0037]

[0038] where k1 is the parameter to be designed.

[0039] Furthermore, design the rudder angle controller to make the yaw angle of the unmanned boat track the desired yaw angle, including:

[0040] Design the virtual controller r v as:

[0041]

[0042] where k2 is the gain of the virtual controller r v , γ1 is the inequality scaling parameter, ψ e is the angle error system of the yaw angle of the unmanned boat relative to the tracked desired yaw angle, ψ e = ψ - ψ c , ψ c is the desired yaw angle, ψ is the yaw angle of the unmanned boat,

[0043] is the derivative of ψ c , x d ′, y d ′ are the first-order partial derivatives of x d , y d with respect to the path variable θ, (x d , y d ) is the desired following path, x d and y d respectively represent the northward and eastward positions of the desired following path in the world coordinate system, u, v, r are the forward, lateral, and yaw velocities of the unmanned boat in the body coordinate system, is the derivative of the path variable θ, m 11 , m 22 are the parameters in the mass matrix of the unmanned boat, d 11 , d 22 are the parameters in the non-linear damping matrix of the unmanned boat;

[0044] The designed rudder angle controller is:

[0045]

[0046] where: k3 is the gain of the rudder angle controller τ r and γ2 is the inequality scaling parameter; m 33 is a parameter in the unmanned boat mass matrix, and d 33 is a parameter in the unmanned boat nonlinear damping matrix, is a partial term after differentiating r,

[0047] is the virtual controller r v derivative, is the second derivative of the path variable θ, x″ d and y″ d are the second partial derivatives of x d and y d with respect to the path variable θ respectively, (x d , y d ) is the desired following path, and x d and y d represent the northward and eastward positions of the desired following path in the world coordinate system respectively;

[0048] Through the designed virtual controller r v and the rudder angle controller τ r the yaw angle of the unmanned boat is made to track the desired yaw angle ψ c .

[0049] Furthermore, a thrust controller is designed to make the resultant velocity of the unmanned boat track the desired resultant velocity. The thrust controller is:

[0050]

[0051] where τ u is the thrust controller, △ = cosβ / m 11 , β is the sideslip angle of the unmanned boat, k4 is the gain of the thrust controller τ u , and γ3 is the inequality scaling parameter; U e is the velocity error system of the resultant velocity of the unmanned boat relative to the desired resultant velocity, U e = U - U c , U is the resultant velocity of the unmanned boat, and U c is the desired resultant velocity,

[0052]

[0053] is a partial term after differentiating U, is the derivative of U c , where m 11 , m 22 is a parameter in the mass matrix of the unmanned boat, and d 11 , d 22 is a parameter in the non-linear damping matrix of the unmanned boat. u, v, and r are respectively the forward, lateral, and yaw velocities of the unmanned boat in the body coordinate system. x d ′, y d ′ are respectively the first-order partial derivatives of x d , y d with respect to the path variable θ. (x d , y d ) is the expected following path. x d and y d respectively represent the positions of the expected following path in the north and east directions in the world coordinate system. is the derivative of the path variable θ, and ψ is the yaw angle;

[0054] According to the designed thrust controller, the resultant velocity of the unmanned boat can track the designed expected resultant velocity.

[0055] The system corresponding to the method includes:

[0056] A model construction unit for constructing a system model of the unmanned boat under the influence of random disturbances;

[0057] A following error calculation unit for setting the expected following path and calculating the tangential and cross following errors of the unmanned boat relative to the expected following path;

[0058] An expected error calculation unit for designing the expected yaw angle, expected resultant velocity, and path variable to make the following error of the unmanned boat relative to the expected following path converge;

[0059] A controller design unit for designing a thrust controller and a rudder angle controller to ensure that the resultant velocity and yaw angle of the unmanned boat track the designed expected resultant velocity and expected yaw angle.

[0060] An electronic device for storing and executing the method, the device includes:

[0061] A memory storing executable program code;

[0062] A processor coupled to the memory;

[0063] The processor calls the executable program code stored in the memory and executes the steps of the method for following the path of the unmanned boat affected by random disturbances.

[0064] Advantages: Compared with the prior art, the remarkable technical effects of the present invention are as follows: (1) Construct the dynamic equation of the unmanned boat system under the influence of random disturbances, and accurately handle the influence of random disturbances on the stability of the unmanned boat system; (2) Design the expected combined velocity, expected yaw angle and path variables of the unmanned boat, realizing the following of the expected following path by the unmanned boat; at the same time, design the thrust controller and rudder angle controller to ensure the tracking of the combined velocity and yaw angle of the unmanned boat to the expected combined velocity and expected yaw angle; the unmanned boat can maintain a high following accuracy for the expected following path and has good robustness under the influence of random disturbances; the structures of the thrust controller and rudder angle controller are simple, do not require complex operations, and are friendly to the software and hardware costs of the system. The simulation results show that the present invention can achieve the path following task of the unmanned boat under the influence of random disturbances. Description of the Drawings

[0065] Figure 1 It is a flowchart of the steps of a method for following the path of an unmanned boat affected by random disturbances according to the present invention;

[0066] Figure 2 It is a schematic diagram of the unmanned boat following the expected following path;

[0067] Figure 3 It is a schematic diagram of the following error of the position of the unmanned boat relative to the expected following path in the world coordinate system. Among them, (a) is a schematic diagram of the following error of the northward position of the unmanned boat relative to the northward position of the expected following path in the world coordinate system, and (b) is a schematic diagram of the following error of the eastward position of the unmanned boat relative to the eastward position of the expected following path in the world coordinate system;

[0068] Figure 4 It is a schematic diagram of the yaw angle of the unmanned boat tracking the expected yaw angle;

[0069] Figure 5 It is a schematic diagram of the combined velocity of the unmanned boat tracking the expected combined velocity. Detailed Embodiments

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0071] As Figure 1 shown, a method for following the path of an unmanned boat affected by random disturbances according to the present invention includes the following specific steps:

[0072] S1. Considering the random disturbances brought by environmental noise, perform random modeling on the unmanned boat system;

[0073] Establish the dynamic equation of the unmanned boat affected by random disturbances;

[0074]

[0075] Where: is the position and yaw angle of the unmanned boat in the world coordinate system, where (x, y) is the northward and eastward positions of the unmanned boat in the world coordinate system, ψ is the yaw angle of the unmanned boat in the world coordinate system, T is the transpose of a matrix or vector, is the derivative of η, are the forward, lateral and yaw velocities of the unmanned boat in the body coordinate system, is the derivative of ξ, is the vector composed of the thrust controller and the rudder angle controller of the unmanned boat, where τ u is the thrust controller, τ r is the rudder angle controller, represents the vector composed of random disturbance coefficients, d1 represents the random disturbance coefficient acting on the forward acceleration of, d2 represents the random disturbance coefficient acting on the lateral acceleration of, d3 represents the random disturbance coefficient acting on the yaw acceleration of, and the white noise B(t) satisfies B(s) is the form of B(t) as the integrand, t is the time, where ω(t) is a one-dimensional Wiener process. J(ψ), M, C(ξ), D(ξ) are the rotation matrix, mass matrix, Coriolis force matrix and nonlinear damping matrix respectively.

[0076] S2. Set the desired following path and calculate the tangential and cross following errors of the unmanned boat relative to the desired following path;

[0077] S21. Define the desired following path;

[0078] Define the desired following path (x d , y d ), where x d and y d represent the northward and eastward positions of the desired following path in the world coordinate system respectively, and are functions of θ, where θ is the path variable.

[0079] S22. Construct the tangent coordinate system and calculate the angle between the tangent direction of the desired following path point and the north direction;

[0080] Establish the tangent coordinate system with the moving tangent direction of the desired following path as the T-axis and the normal direction as the N-axis, and calculate the derivatives of x d and y d to get:

[0081]

[0082] Among them, and are the derivatives of x d and y d respectively, and is the derivative of the path variable θ; x d ′, y d ′ are the first-order partial derivatives of x d , y d with respect to the path variable θ respectively. Then, the angle ψ d between the tangent direction of the expected following path point and the north direction at this moment can be calculated as:

[0083] ψ d = atan2(y′ d , x′ d ), ψ d ∈[-π, π] (3)

[0084] S23. Describe the position error system of the unmanned boat relative to the expected following path in the tangent coordinate system;

[0085] Through the on-board integrated navigation and positioning device, the unmanned boat can obtain its own position, speed and other information, and convert the position following error in the world coordinate system to the tangent coordinate system. At this time, the position error system of the unmanned boat relative to the expected following path is calculated as follows:

[0086]

[0087] Among them, x e is the tangential following error of the unmanned boat in the tangent coordinate system, y e is the cross following error of the unmanned boat in the tangent coordinate system, and (x, y) are the northward and eastward positions of the unmanned boat in the world coordinate system.

[0088] S24. Calculate the derivative of the position error system of the unmanned boat relative to the expected following path;

[0089] Derive the position error system of the unmanned boat relative to the expected following path in S23 as follows:

[0090]

[0091] Among them, and are the derivatives of x e and y e respectively, is the magnitude of the combined velocity of the unmanned boat, and ψ ω= ψ + β is the heading angle of the unmanned boat, where ψ is the yaw angle of the unmanned boat in the world coordinate system, and β = atan2(v, u) is the sideslip angle of the unmanned boat. is the derivative of ψ d of.

[0092] S3. Design the desired yaw angle, desired resultant velocity, and path variable so that the tangential and cross-track following errors of the unmanned boat relative to the desired following path converge.

[0093] S31. Design the desired resultant velocity and desired yaw angle.

[0094] For the resultant velocity U and yaw angle ψ of the unmanned boat in the position error system of the unmanned boat relative to the desired following path, design the desired resultant velocity U c and the desired yaw angle ψ c as follows:

[0095]

[0096] where: v d is the reference velocity designed for the derivative of the path variable θ , and d is the look-ahead distance.

[0097] S32. Calculate the derivative of the position error system of the unmanned boat relative to the desired following path based on the desired resultant velocity and desired yaw angle.

[0098] Substitute the desired resultant velocity and desired yaw angle designed in S31 into the derivative of the position error system of the unmanned boat relative to the desired following path after differentiation in S24, and the calculation is as follows:

[0099]

[0100] where: α1 = u d v d / d > 0.

[0101] S33. Design the derivative of the path variable.

[0102] To ensure that the unmanned boat can follow the desired following path, design the derivative of the path variable θ as follows:

[0103]

[0104] where k1 is a parameter to be designed.

[0105] S4. Design the thrust controller and rudder angle controller to ensure that the resultant velocity and yaw angle of the unmanned boat track the desired resultant velocity and desired yaw angle.

[0106] S41. Design the rudder angle controller so that the yaw angle of the unmanned boat tracks the desired yaw angle;

[0107] Define the angle error system ψ of the yaw angle ψ of the unmanned boat relative to the tracked desired yaw angle ψ c as follows: e As follows:

[0108] ψ e = ψ - ψ c (9)

[0109] Derive ψ as follows: e Derive it as follows:

[0110]

[0111] Where:

[0112]

[0113] ψ c The term after derivation, r v is the virtual controller, r e = r - r v is the error between the yaw angular velocity r of the unmanned boat and the virtual controller r v between, m 11 , m 22 , are the parameters in the mass matrix of the unmanned boat, d 11 , d 22 is the parameter in the non - linear damping matrix of the unmanned boat, τ u is the thrust controller of the unmanned boat.

[0114] Design the specific form of the virtual controller r v as follows:

[0115]

[0116] Where: k2 is the gain of the virtual controller r v and γ1 is the inequality scaling parameter.

[0117] Derive r e as follows:

[0118]

[0119] Where: is a partial term after deriving r,

[0120]

[0121] is the term after deriving r v m 33 is the parameter in the mass matrix of the unmanned boat, d 33is a parameter in the non - linear damping matrix of the unmanned boat, is the second - order derivative of θ, x′ d ′ and y′ d ′ are the second - order partial derivatives of x d , y d with respect to the path variable θ respectively.

[0122] Design the following rudder - angle controller:

[0123]

[0124] where: k3 is the gain of the rudder - angle controller τ r and γ2 is the inequality scaling parameter.

[0125] Through the designed virtual controller r v and the rudder - angle controller τ r the yaw angle of the unmanned boat can track the desired yaw angle ψ c .

[0126] S42. Design a thrust controller so that the resultant velocity of the unmanned boat tracks the desired resultant velocity;

[0127] Define the velocity error system U of the resultant velocity of the unmanned boat relative to the desired resultant velocity e as follows:

[0128] U e = U - U c (14)

[0129] Differentiate U e as follows:

[0130]

[0131] where:

[0132] is the derivative of U c , is a partial term after differentiating U

[0133] Design the following thrust controller:

[0134]

[0135] where: △ = cosβ / m 11 , k4 is the gain of the thrust controller τ u and γ3 is the inequality scaling parameter. According to the designed thrust controller, the resultant velocity of the unmanned boat can track the desired resultant velocity designed in S31.

[0136] On the one hand, the method of the present invention can ensure the following performance of the unmanned boat for the expected following path. On the other hand, it can improve the robustness of the path following algorithm of the unmanned boat under random disturbances.

[0137] In this embodiment, MATLAB 2023b is used as the simulation calculation software to simulate the path following motion of the unmanned boat under random disturbances such as environmental noise. The inertial sensors carried by the unmanned boat include an accelerometer, a magnetometer, and a gyroscope. In the simulation environment, the expected path is set as: x d = 0.015θ 2 - 0.85θ - 18, y d = -θ, and the initial value of the path variable θ is set to -15.

[0138] To prove the effectiveness and superiority of the proposed control algorithm of the invention, in this example, a PID controller is selected for comparison. The initial position, yaw angle, and initial speed values of the unmanned boat are set as: η = [-3, 7, -π] T , ξ = [0.1, 0.1, 0.1] T m / s; τ d is set as: τ d = [0, 0, sin(t)] T ; in the simulation environment, the virtual controller r v gain is set as: k2 = 4.5; the rudder angle controller τ r gain is set as: k3 = 2; the thrust controller τ u gain is set as: k4 = 2; the inequality scaling parameter is set as: γ1 = 0, γ2 = 5, γ3 = 0; the reference speed v d is set as: v d = 1; the look-ahead distance d is set as: d = 1; k1 is set as: k1 = 0.3, and the simulation duration is 30 seconds.

[0139] Figure 2 The path following schematic diagram of the unmanned boat is given. The black solid line in the figure is the moving path of the unmanned boat corresponding to the method of the present invention, the black double-dashed line is the moving path of the unmanned boat under the PID control algorithm, and the black dotted line is the expected following path. From Figure 3 it can be seen that the proposed unmanned boat path following method and system of the present invention can ensure the following of the unmanned boat for the expected following path in the presence of random disturbances, and the following effect is significantly better than the traditional PID control method.

[0140] Figure 3 The errors of the northward position and eastward position of the unmanned boat relative to the northward position and eastward position of the expected following path are given respectively. Figure 3In (a), the black solid line is the relative error of the northward position of the unmanned boat with respect to the northward position of the desired following path. The black double-dashed line is the relative error of the northward position of the unmanned boat with respect to the northward position of the desired following path under the PID control algorithm. The black dotted line is the origin. Figure 3 In (b), the black solid line is the relative error of the eastward position of the unmanned boat with respect to the eastward position of the desired following path. The black double-dashed line is the relative error of the eastward position of the unmanned boat with respect to the eastward position of the desired following path under the PID control algorithm. The black dotted line is the origin. From Figure 4 it can be seen that the unmanned boat path following method and system proposed by the present invention can ensure that the following error of the unmanned boat with respect to the desired following path quickly converges near the origin, which is significantly better than the convergence effect under the PID control algorithm.

[0141] Figure 4 The combined velocity of the unmanned boat and the desired combined velocity are given. The black solid line represents the combined velocity of the unmanned boat, and the black double-dashed line represents the desired combined velocity of the unmanned boat. From the simulation results, it can be seen that the two lines are almost coincident, indicating that the designed thrust controller can ensure that the combined velocity of the unmanned boat can track the desired combined velocity.

[0142] Figure 5 The yaw angle of the unmanned boat and the desired yaw angle are given. The black solid line represents the yaw angle of the unmanned boat, and the black double-dashed line represents the desired yaw angle of the unmanned boat. From the simulation results, it can be seen that the two lines are almost coincident, indicating that the designed rudder angle controller can ensure that the yaw angle of the unmanned boat can track the desired yaw angle.

[0143] It can be clearly seen from the above simulation results that the unmanned boat path following method and system affected by random disturbances proposed by the present invention improve the robustness of the unmanned boat system in the face of random disturbances while ensuring the path following accuracy.

[0144] The system corresponding to the method includes:

[0145] A model construction unit for constructing a model of the unmanned boat system under the influence of random disturbances;

[0146] A following error calculation unit for setting a desired following path and calculating the tangential and cross following errors of the unmanned boat with respect to the desired following path;

[0147] A desired error calculation unit for designing a desired yaw angle, a desired combined velocity, and path variables to make the following error of the unmanned boat with respect to the desired following path converge;

[0148] A controller design unit for designing a thrust controller and a rudder angle controller to ensure that the combined velocity and yaw angle of the unmanned boat track the designed desired combined velocity and desired yaw angle.

[0149] An electronic device for storing and executing the method, the device comprising:

[0150] A memory storing executable program code;

[0151] A processor coupled to the memory;

[0152] The processor calls the executable program code stored in the memory and executes the steps of the unmanned boat path following method affected by random disturbances.

Claims

1. A path following method for an unmanned boat affected by random perturbations, characterized in that, It includes the following steps: Considering the random disturbance caused by environmental noise, a stochastic model of the unmanned boat system is established; Set the desired following path and calculate the tangential and cross following errors of the unmanned boat relative to the desired following path; including: (1) Establish a tangent coordinate system with the desired moving tangent direction along the path as the T-axis and the normal direction as the N-axis, and calculate the angle ψ between the moving tangent direction of the path point and the north direction. d ; (2) Convert the position following error of the unmanned boat relative to the desired following path in the world coordinate system to the tangent coordinate system; the position error system of the unmanned boat relative to the desired following path in the tangent coordinate system is expressed as: where x e is the tangential following error of the unmanned boat in the tangent coordinate system, y e is the cross following error of the unmanned boat in the tangent coordinate system, and (x, y) are the northward and eastward positions of the unmanned boat in the world coordinate system, x d and y d respectively represent the northward and eastward positions of the desired following path in the world coordinate system; (3) Calculate the derivative of the position error system of the unmanned boat relative to the desired following path in the tangent coordinate system; Design the desired yaw angle, desired resultant velocity and path variables so that the tangential and cross following errors of the unmanned boat relative to the desired following path converge; Design a thrust controller and a rudder angle controller to ensure that the resultant velocity and yaw angle of the unmanned boat track the desired resultant velocity and desired yaw angle.

2. A path following method for an unmanned boat affected by random disturbances according to claim 1, characterized in that The model expression of the unmanned boat system under the influence of random disturbance is: Among them, is the position and yaw angle of the unmanned boat in the world coordinate system. Among them, (x, y) is the northward and eastward positions of the unmanned boat in the world coordinate system, ψ is the yaw angle of the unmanned boat in the world coordinate system, T is the transpose of a matrix or vector, is the derivative of η, are the forward, lateral, and yaw velocities of the unmanned boat in the body coordinate system, is the derivative of ξ, is the vector composed of the thrust controller and the rudder angle controller of the unmanned boat, τ u is the thrust controller, τ r is the rudder angle controller, represents the vector composed of random disturbance coefficients. d1 represents the random disturbance coefficient acting on the forward acceleration d2 represents the random disturbance coefficient acting on the lateral acceleration d3 represents the random disturbance coefficient acting on the yaw acceleration The random disturbance coefficient of, B(t) is white noise, and J(ψ), M, C(ξ), D(ξ) are the rotation matrix, mass matrix, Coriolis force matrix, and nonlinear damping matrix respectively.

3. A path following method for an unmanned boat affected by random disturbances according to claim 1, characterized in that The desired following path is expressed as (x d , y d ), where x d and y d represent the northward and eastward positions of the desired following path in the world coordinate system respectively, and are functions of θ, where θ is the path variable.

4. A path following method for an unmanned boat affected by random disturbances according to claim 1, characterized in that The included angle ψ between the moving tangent direction of the path point and the north direction d The calculation formula is as follows: ψ d = atan2(y' d , x' d ), ψ d ∈ [-π, π] where x d ′, y d ′ are the first-order partial derivatives of x d , y d with respect to the path variable θ, x d and y d represent the northward and eastward positions of the expected following path in the world coordinate system respectively, and (x d , y d ) is the expected following path; The derivative of the position error system of the unmanned boat relative to the desired following path is: Among them, and are the derivatives of x e and y e respectively, is the resultant velocity of the unmanned boat, u and v are the forward and lateral velocities of the unmanned boat in the body coordinate system, and ψ ω = ψ + β is the heading angle of the unmanned boat, ψ is the yaw angle of the unmanned boat, and β = atan2(v, u) is the sideslip angle of the unmanned boat. is the derivative of ψ d respectively, is the derivative of the path variable θ.

5. A path following method for an unmanned boat affected by random perturbations according to claim 1, characterized in that, Design the desired yaw angle, desired resultant velocity and path variables so that the tangential and cross following errors of the unmanned boat relative to the desired following path converge, including: (1) For the combined velocity U and yaw angle ψ of the unmanned boat in the error system, design the desired combined velocity U c and the desired yaw angle ψ c : where, ψ d is the angle between the moving tangent direction of the path point and the north direction, y e is the cross-tracking error of the unmanned boat in the tangent coordinate system, d is the forward-looking distance, β = atan2(v, u) is the sideslip angle of the unmanned boat, and u and v are the forward and lateral velocities of the unmanned boat in the body coordinate system, x d ′, y d ′ are the first-order partial derivatives of x d , y d with respect to the path variable θ, (x d , y d ) is the expected following path, x d and y d represent the northward and eastward positions of the expected following path in the world coordinate system respectively, v d is the reference speed designed for , is the derivative of the path variable θ; (2) Calculate the derivative of the position error system of the unmanned boat relative to the desired following path based on the desired resultant velocity and desired yaw angle; Among them, and are the derivatives of x e and y e respectively. x e is the tangential following error of the unmanned boat in the tangent coordinate system, and y e is the cross following error of the unmanned boat in the tangent coordinate system. is the derivative of ψ d , and α1 = u d v d / d > 0; (3)Derivative of the design path variable θ is as follows: where, k1 is a parameter to be designed.

6. A path following method for an unmanned boat affected by random perturbations according to claim 1, characterized in that, Design a rudder angle controller so that the yaw angle of the unmanned boat tracks the desired yaw angle, including: Design the virtual controller r v It is: where k2 is the gain of the virtual controller r v , γ1 is the inequality scaling parameter, and ψ e is the angle error system of the yaw angle of the unmanned surface vehicle relative to the tracking desired yaw angle, and ψ e = ψ - ψ c , ψ c is the desired yaw angle, and ψ is the yaw angle of the unmanned surface vehicle, is ψ c 's derivative, d1 represents the random disturbance coefficient acting on the forward acceleration and d2 represents the random disturbance coefficient acting on the lateral acceleration . x d ', y d ' are the first-order partial derivatives of x d , y d with respect to the path variable θ. (x d , y d ) is the desired following path, x d and y d represent the northward and eastward positions of the desired following path in the world coordinate system respectively. u, v, and r are the forward, lateral, and yaw velocities of the unmanned boat in the body coordinate system, is the derivative of the path variable θ, m 11 , m 22 are the parameters in the mass matrix of the unmanned boat, d 11 , d 22 are the parameters in the nonlinear damping matrix of the unmanned boat; The designed rudder angle controller is: where: k3 is the gain of the rudder angle controller τ r , γ2 is the inequality scaling parameter, r e is the error between the yaw angular velocity r of the unmanned surface vehicle and the virtual controller r v ; m 33 is a parameter in the mass matrix of the unmanned surface vehicle, d 33 is a parameter in the nonlinear damping matrix of the unmanned surface vehicle, is a partial term after differentiating r, d3 represents the random disturbance coefficient acting on the yaw acceleration ; is the derivative of the virtual controller r v ; is the second derivative of the path variable θ, x′ d ′ and y′ d ′ are the second partial derivatives of x d and y d with respect to the path variable θ respectively, (x d , y d ) is the desired following path, x d and y d represent the northward and eastward positions of the desired following path in the world coordinate system respectively; Through the designed virtual controller r v and the rudder angle controller τ r the unmanned surface vehicle's yaw angle tracks the desired yaw angle ψ c .

7. A path following method for an unmanned boat affected by random disturbances according to claim 1, characterized in that Design a thrust controller so that the resultant velocity of the unmanned boat tracks the desired resultant velocity, and the thrust controller is: where τ u is the thrust controller, △ = cosβ / m 11 , β is the sideslip angle of the unmanned boat, k4 is the gain of the thrust controller τ u , γ3 is the inequality scaling parameter; U e is the velocity error system of the resultant velocity of the unmanned boat relative to the desired resultant velocity, U e = U - U c , U is the resultant velocity of the unmanned boat, U c is the desired resultant velocity, is a partial term after the derivative of U, where d1 represents the random perturbation coefficient acting on the forward acceleration and d2 represents the random perturbation coefficient acting on the lateral acceleration , and is U c 's derivative, where m 11 , m 22 are parameters in the mass matrix of the unmanned boat, and d 11 , d 22 are parameters in the non - linear damping matrix of the unmanned boat. u, v, and r are the forward, lateral, and yaw velocities of the unmanned boat in the body coordinate system respectively. x d ', y d ' are the first - order partial derivatives of x d , y d with respect to the path variable θ. (x d , y d ) is the desired following path. x d and y d represent the northward and eastward positions of the desired following path in the world coordinate system respectively, is the derivative of the path variable θ, and ψ is the yaw angle; According to the designed thrust controller, the resultant velocity of the unmanned boat can track the designed desired resultant velocity.

8. An unmanned boat path following system affected by random disturbances, characterized in that, Including: A model construction unit for constructing a model of the unmanned boat system under the influence of random disturbance; A following error calculation unit for setting the desired following path and calculating the tangential and cross following errors of the unmanned boat relative to the desired following path; including: (1) Establish a tangent coordinate system with the expected moving tangent direction along the path as the T-axis and the normal direction as the N-axis, and calculate the angle ψ between the moving tangent direction of the path point and the north direction. d ; (2) Convert the position following error of the unmanned boat relative to the desired following path in the world coordinate system to the tangent coordinate system; the position error system of the unmanned boat relative to the desired following path in the tangent coordinate system is expressed as: Among them, x e is the tangential following error of the unmanned boat in the tangent coordinate system, and y e is the cross following error of the unmanned boat in the tangent coordinate system. (x, y) are the northward and eastward positions of the unmanned boat in the world coordinate system. x d and y d respectively represent the northward and eastward positions of the expected following path in the world coordinate system; (3) Calculate the derivative of the position error system of the unmanned boat relative to the desired following path in the tangent coordinate system; A desired error calculation unit for designing the desired yaw angle, desired resultant velocity and path variables so that the following error of the unmanned boat relative to the desired following path converges; A controller design unit for designing a thrust controller and a rudder angle controller to ensure that the resultant velocity and yaw angle of the unmanned boat track the designed desired resultant velocity and desired yaw angle.

9. An electronic device, characterized in that, The device includes: A memory storing executable program code; A processor coupled to the memory; The processor calls the executable program code stored in the memory and executes the steps of the method for following the path of an unmanned boat affected by random disturbance as described in any one of claims 1-7.

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