Rapid guidance method for unmanned ship

Abstract

The invention relates to a rapid guidance method for an unmanned ship, which comprises the following steps of: establishing a parameterized reference path, determining a position and attitude relationship of the unmanned ship on a horizontal plane, designing a finite time drift angle observer for accurately observing an unknown drift angle of the unmanned ship, defining an estimated value of the drift angle, an adjusting parameter and an error term, and determining the position and attitude relationship of the unmanned ship on the horizontal plane. Deriving a derivative expression of the error term, proving that the error term converges to zero in finite time, establishing a drift angle estimation formula, and proving that the observation error converges to zero in finite time; designing a virtual speed and an updating law thereof; designing a nonlinear function for accelerating the convergence speed of the lateral error; establishing a line-of-sight tracking angle formula; and by parameterizing the reference path and accurately calculating the error between the unmanned ship and the virtual target point and combining the derivative expression of the error, the unmanned ship can be more accurately controlled to sail along the preset path, and the path tracking precision is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of ship manufacturing and installation technology, and in particular to a rapid guidance method for an unmanned boat. Background Art

[0002] When performing path tracking operations, ships will drift laterally due to the influence of wind, waves and currents, and have lateral speed. Therefore, there is a certain deviation between the ship's heading angle and the actual direction of movement of the ship, namely the drift angle. Excessive drift angle will affect the accuracy of ship path tracking. Improving the guidance angle accuracy by observing the drift angle is a solution. In recent years, many methods have been proposed to improve the line of sight method, but they are all lacking for the guidance and control of unmanned boats; therefore, we improve the current rapid guidance method of unmanned boats to meet the use requirements. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a rapid guidance method for an unmanned boat with fast and accurate guidance in view of the deficiencies in the prior art.

[0004] The technical problem to be solved by the present invention is achieved through the following technical solution, a rapid guidance method for an unmanned boat, the steps of which are as follows:

[0005] Step 1: Establish a parameterized reference path, determine the position and attitude relationship of the unmanned boat on the horizontal plane, define the path parameter variable, express the path shape through a function containing the variable, determine the coordinate points of the reference path and the tangent angle of the path, calculate the error between the position of the unmanned boat and the virtual target point on the parameterized path, differentiate the path parameter variable and the position of the unmanned boat, derive the derivative expression of the error, and define the combined speed of the unmanned boat, the drift angle and the moving speed of the virtual target point;

[0006] Step 2: Design a finite-time drift angle observer to accurately observe the unknown drift angle of the unmanned boat, define the estimated value of the drift angle, adjustment parameters and error term, derive the derivative expression of the error term, and prove that the error term converges to zero in a finite time, establish a drift angle estimation formula, and prove that its observation error converges to zero in a finite time; design the virtual speed and its update law to enhance the robustness of the system;

[0007] Step 3: Design a nonlinear function to speed up the convergence of the lateral error;

[0008] Step 4: Based on the above error calculation, drift angle observation and nonlinear function design, a line of sight tracking angle formula is established so that when the lateral path error is far away from the balance point, the tracking angle becomes smaller and the speed gradually increases to achieve faster convergence. When the lateral error approaches the balance point, the tracking angle approaches the preset value.

[0009] The technical problem to be solved by the present invention can also be achieved by the following technical solution. In the above-mentioned rapid guidance method for an unmanned boat, in step 1, the error between the position of the unmanned boat and the virtual target point on the parameterized path is expressed in the reference coordinate system as follows:

[0010] x e ,y e The derivative is:

[0011] Among them, ω represents the path parameter variable, the shape of the path is represented by a function containing ω, and the coordinate point of the reference path is represented by (x k (ω),y k (ω)) represents the path tangent angle, and the path tangent angle is represented by ψ k =arctan(y' k / x' k ),in

[0012] The technical problem to be solved by the present invention can also be achieved by the following technical solution. In the above-mentioned rapid guidance method for an unmanned boat, in step 2, the expression of the drift angle observer is:

[0013] where h1 = Usin(ψ-ψ k +β), They are y e , the estimated value of h1, κ i (i=1,2), θ1 are all positive adjustment parameters, with error The derivative of it is:

[0014] It converges to zero in a finite time, that is, there exists a time 0<T β <∞, so that The addition is to improve the robustness of the system.

[0015] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the above-mentioned rapid guidance method for an unmanned boat is: Substitution It can be deduced that The combined speed of the unmanned boat is defined as u is the longitudinal velocity, v is the lateral velocity, and the drift angle is defined as β = arctan (v / u), u p is the moving speed of the virtual target point along the reference path,

[0016] The technical problem to be solved by the present invention can also be achieved by the following technical solution. In the above-mentioned rapid guidance method for an unmanned boat, in step 2, the drift angle estimation formula is: Expressed as The observation error of the drift angle is Knowable Converges to zero in finite time, so Converges to zero in finite time, considering the error x e Convergence of, design virtual speed u p for where k x is a positive adjustment parameter, and the update law of ω is

[0017] The technical problem to be solved by the present invention can also be achieved by the following technical solution. In the above-mentioned rapid guidance method for an unmanned boat, the nonlinear function in step 3 is

[0018] The technical problem to be solved by the present invention can also be achieved by the following technical solution. In the above-mentioned rapid guidance method for an unmanned boat, the tracking angle formula of the line of sight method in step 4 is: Δ is the foresight distance, from which we can see that when the lateral path error is far away from the equilibrium point becomes smaller, Ξ(y e ) gradually increases, a faster convergence can be obtained; when the lateral error approaches the equilibrium point, Ξ(y e ) approaches

[0019] The technical problem to be solved by the present invention can also be achieved by the following technical solution: a method for proving the convergence of the path tracking error of an unmanned boat, which is used to prove the rapid guidance method of the above unmanned boat:

[0020] Will Simplified to in

[0021] Select the Lyapunov function as Taking the time derivative of both sides, we get Among them U max is the maximum value of U, Ξ max (y e ) is Ξ(y e ), let Then there is Therefore the path following error is globally asymptotically stable.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are:

[0023] (1) Improving path tracking accuracy: By parameterizing the reference path and accurately calculating the error between the UAV and the virtual target point, combined with the derivative expression of the error, the UAV can be more accurately controlled to navigate along the predetermined path, significantly improving the path tracking accuracy.

[0024] (2) Enhanced robustness and adaptability: The design of the finite-time drift angle observer enables the unmanned vehicle to accurately estimate and compensate for the unknown drift angle in real time, thereby effectively coping with the impact of complex and changeable marine environments (such as strong winds, surges, currents, etc.) on the guidance system, and enhancing the system's robustness and adaptability to time-varying large drift angles.

[0025] (3) Accelerating convergence speed: The introduction of a nonlinear function based on the lateral error can dynamically adjust the line of sight tracking angle according to the size of the error, so that the unmanned boat accelerates when it is far away from the path and tracks smoothly when it is close to the path, thereby significantly accelerating the convergence speed and improving the guidance efficiency.

[0026] (4) Optimizing control strategy: Based on the comprehensive results of error calculation, drift angle observation and nonlinear function design, the established line-of-sight tracking angle formula can achieve a more flexible and efficient control strategy, allowing the unmanned boat to maintain stable tracking performance under different working conditions, thereby improving the control quality of the overall system.

[0027] (5) Improving system reliability and safety: Since this method can achieve the convergence of the drift angle observation error within a limited time, it reduces the risk of path deviation caused by inaccurate drift angle estimation, thereby improving the reliability and safety of the autonomous navigation of the unmanned boat. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of path tracking of the present invention;

[0029] Figure 2 This is a schematic diagram of curve path simulation comparison of the present invention;

[0030] Figure 3 A schematic diagram showing a comparison of lateral errors in the curve path simulation of the present invention;

[0031] Figure 4 This is a schematic diagram of the straight line path simulation comparison of the present invention;

[0032] Figure 5 It is a schematic diagram of the lateral error comparison of the straight path simulation of the present invention. DETAILED DESCRIPTION

[0033] The specific technical solutions of the present invention are further described below with reference to the accompanying drawings, so as to facilitate further understanding of the present invention by those skilled in the art, and do not constitute a limitation on the rights thereof.

[0034] Example 1, reference Figure 1-5 , a rapid guidance method for an unmanned boat, the steps of which are as follows:

[0035] Step 1: Establish a parameterized reference path, determine the position and attitude relationship of the unmanned boat on the horizontal plane, define the path parameter variable, express the path shape through a function containing the variable, determine the coordinate points of the reference path and the tangent angle of the path, calculate the error between the position of the unmanned boat and the virtual target point on the parameterized path, differentiate the path parameter variable and the position of the unmanned boat, derive the derivative expression of the error, and define the combined speed of the unmanned boat, the drift angle and the moving speed of the virtual target point;

[0036] Step 2: Design a finite-time drift angle observer to accurately observe the unknown drift angle of the unmanned boat, define the estimated value of the drift angle, adjustment parameters and error term, derive the derivative expression of the error term, and prove that the error term converges to zero in a finite time, establish a drift angle estimation formula, and prove that its observation error converges to zero in a finite time; design the virtual speed and its update law to enhance the robustness of the system;

[0037] Step 3: Design a nonlinear function to speed up the convergence of the lateral error;

[0038] Step 4: Based on the above error calculation, drift angle observation and nonlinear function design, establish the tracking angle formula of the line of sight method, so that when the lateral path error is far away from the balance point, the tracking angle becomes smaller and the speed gradually increases to achieve faster convergence. When the lateral error approaches the balance point, the tracking angle approaches the preset value.

[0039] In step 1, the error between the position of the unmanned boat and the virtual target point on the parameterized path is expressed in the reference coordinate system as follows:

[0040] x e ,y e The derivative is:

[0041] Among them, ω represents the path parameter variable, the shape of the path is represented by a function containing ω, and the coordinate point of the reference path is represented by (x k (ω),y k (ω)) represents the path tangent angle, and the path tangent angle is represented by ψ k =arctan(y' k / x' k ),in

[0042] The expression of the drift angle observer is:

[0043] where h1 = Usin(ψ-ψ k +β), They are y e , the estimated value of h1, κ i (i=1,2), θ1 are all positive adjustment parameters, with error The derivative of it is:

[0044] It converges to zero in a finite time, that is, there exists a time 0<T β <∞, so that The addition is to improve the robustness of the system;

[0045] Will Substitution It can be deduced that The combined speed of the unmanned boat is defined as u is the longitudinal velocity, v is the lateral velocity, and the drift angle is defined as β = arctan (v / u), u p is the moving speed of the virtual target point along the reference path,

[0046] In step 2, the drift angle estimation formula is given by Expressed as The observation error of the drift angle is Knowable Converges to zero in finite time, so Converges to zero in finite time, considering the error x e Convergence of, design virtual speed u p for where k x is a positive adjustment parameter, and the update law of ω is

[0047] The nonlinear function in step 3 is Among them, a1, b1 and c1 are all parameter adjustment constants, c1 is between 0-5 and is adjusted according to the simulation effect, and the absolute value in the denominator bracket represents the lateral error;

[0048] The tracking angle formula of the line of sight method in step 4 is It can be seen that β is the drift angle, when the lateral path error is far away from the equilibrium point becomes smaller, Ξ(y e ) gradually increases, a faster convergence can be obtained; when the lateral error approaches the equilibrium point, Ξ(y e ) approaches

[0049] Example 2, a method for proving the convergence of the unmanned boat path tracking error, which is used to prove the rapid guidance method of the unmanned boat described in Example 1:

[0050] Will Simplified to in

[0051] Select the Lyapunov function as Taking the time derivative of both sides, we get Among them U max is the maximum value of U, max (y e ) is Ξ(y e ), let Then there is Therefore the path following error is globally asymptotically stable.

[0052] It should be noted that:

[0053] for Figure 2-Figure 3 For example, the trajectory formed by the integrated sight line method in the simulation is named No. 1, the trajectory formed by the finite time prediction sight line method is named No. 2, and the trajectory formed by the rapid guidance method of the unmanned boat in Example 1-2 is named No. 3;

[0054] for Figure 4-Figure 5 In the straight line path tracking simulation, No. 1 is the trajectory formed by removing the nonlinear function from the rapid guidance method of the unmanned boat in Example 1-2, and No. 2 is the trajectory formed by the rapid guidance method of the unmanned boat in Example 1-2.

Claims

1. A rapid guidance method for an unmanned boat, characterized in that: The steps are as follows: Step 1: Establish a parameterized reference path, determine the position and attitude relationship of the unmanned boat on the horizontal plane, define the path parameter variable, express the path shape through a function containing the variable, determine the coordinate points of the reference path and the tangent angle of the path, calculate the error between the position of the unmanned boat and the virtual target point on the parameterized path, differentiate the path parameter variable and the position of the unmanned boat, derive the derivative expression of the error, and define the combined speed of the unmanned boat, the drift angle and the moving speed of the virtual target point; Step 2: Design a finite-time drift angle observer to accurately observe the unknown drift angle of the unmanned boat, define the estimated value of the drift angle, adjustment parameters and error term, derive the derivative expression of the error term, and prove that the error term converges to zero in a finite time, establish a drift angle estimation formula, and prove that its observation error converges to zero in a finite time; design the virtual speed and its update law to enhance the robustness of the system; Step 3: Design a nonlinear function to speed up the convergence of the lateral error; Step 4: Based on the above error calculation, drift angle observation and nonlinear function design, a line of sight tracking angle formula is established so that when the lateral path error is far away from the balance point, the tracking angle becomes smaller and the speed gradually increases to achieve faster convergence. When the lateral error approaches the balance point, the tracking angle approaches the preset value.

2. The rapid guidance method of an unmanned boat according to claim 1, characterized in that: In step 1, the error between the position of the unmanned boat and the virtual target point on the parameterized path is expressed in the reference coordinate system as follows: x e ,y e The derivative is: Where ω represents the path parameter variable, the shape of the path is represented by a function containing ω, and the coordinate point of the reference path is represented by (x k (ω),y k (ω)) represents the path tangent angle, and the path tangent angle is represented by ψ k =arctan(y' k / x' k ),in 3. The rapid guidance method of an unmanned boat according to claim 2, characterized in that: In step 2, the expression of the drift angle observer is: where h1 = Usin(ψ-ψ k +β), They are y e , the estimated value of h1, κ i (i=1,2), θ1 are all positive adjustment parameters, with error The derivation of it is: It converges to zero in a finite time, that is, there exists a time 0<T β <∞, so that The addition is to improve the robustness of the system.

4. The rapid guidance method of an unmanned boat according to claim 3, characterized in that: Will Substitution It can be deduced that The combined speed of the unmanned boat is defined as u is the longitudinal velocity, v is the lateral velocity, and the drift angle is defined as β = arctan (v / u), u p is the moving speed of the virtual target point along the reference path, 5. The rapid guidance method of an unmanned boat according to claim 4, characterized in that: In step 2, the drift angle estimation formula is given by Expressed as The observation error of the drift angle is Knowable Converges to zero in finite time, so Converges to zero in finite time, considering the error x e Convergence of, design virtual speed u p for where k x is a positive adjustment parameter, and the update law of ω is 6. The rapid guidance method of an unmanned boat according to claim 5, characterized in that: The nonlinear function in step 3 is 7. The rapid guidance method of an unmanned boat according to claim 6, characterized in that: The tracking angle formula of the line of sight method in step 4 is Δ is the foresight distance, from which we can see that when the lateral path error is far away from the equilibrium point becomes smaller, Ξ(y e ) gradually increases, a faster convergence can be obtained; when the lateral error approaches the equilibrium point, Ξ(y e ) approaches 8. A method for proving the convergence of an unmanned boat path tracking error, which is used to prove the rapid guidance method of the unmanned boat described in claim 7, characterized in that: Will Simplified to in Select the Lyapunov function as Taking the time derivative of both sides, we get Among them U max is the maximum value of U, max (y e ) is Ξ(y e ), let Then there is Therefore the path following error is globally asymptotically stable.

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