A heading control method for unmanned surface vehicle under data loss conditions

Abstract

The present invention relates to a method for controlling the heading of an unmanned surface vehicle under data loss conditions, comprising: step S1: constructing a model-free sliding mode controller with output compensation, wherein the output compensation is determined by an event triggering mechanism; step S2: controlling the heading of the unmanned surface vehicle by the model-free sliding mode controller with output compensation. The present invention efficiently and accurately controls the unmanned surface vehicle, solves the problem of data loss caused by network congestion, and effectively saves communication resources.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned surface vehicle control, and in particular to a method for controlling the heading of an unmanned surface vehicle in the event of data loss. Background Art

[0002] Unmanned surface vehicles (USVs) are offshore platforms designed to perform tasks on water. In recent years, they have attracted widespread attention and have been applied in the fields of maritime territorial surveillance and marine resource development. USVs have complex structures and are easily affected by environmental factors, making it difficult to establish an accurate mathematical model. MFAC is an online data-driven control method in which the design of the controller does not explicitly depend on the mathematical model information of the controlled system. Sliding mode control is a widely used nonlinear control method that helps to perform robust system control under uncertain parameters and external disturbances. Although methods such as MFAC (model-free adaptive control) and sliding mode control have been used for many real-world motion control problems, how to achieve resource-efficient control is still worth considering. In addition, in a complex network environment, challenges such as network congestion, device failure, and signal interference often occur, resulting in data loss during transmission. Therefore, developing a method for USV heading control in the case of data loss has become an important research direction. On the other hand, the heading control method needs to consider the utilization of communication resources and reduce the number of communications and energy consumption. Summary of the invention

[0003] To this end, the technical problem to be solved by the present invention is to overcome the problems in the prior art of inefficient control of unmanned surface vehicles and data loss caused by network congestion.

[0004] In order to solve the above technical problems, the present invention provides a heading control method for an unmanned surface vehicle in the case of data loss, comprising:

[0005] Step S1: constructing a model-free sliding mode controller with output compensation, wherein the output compensation is determined by an event triggering mechanism;

[0006] Step S2: Implementing heading control of the unmanned surface vehicle through the model-free sliding mode controller with output compensation.

[0007] In one embodiment of the present invention, in step S1, a model-free sliding mode controller with output compensation is constructed, and the formula is:

[0008]

[0009] in, λ is a constant, β is a constant greater than 0, y d (k+1) is the expected output, k is the time, y2(k) is the output compensation, is a pseudo partial derivative.

[0010] In one embodiment of the present invention, the pseudo partial derivative It is expressed as:

[0011]

[0012] Among them, α∈(0,1], θ>0, Δu(k-1) is u(k-1)-u(k-2);

[0013] The pseudo partial derivative The reset mechanism formula is:

[0014]

[0015] in, is a positive number, yes The initial value of , sign() is the sign function.

[0016] In one embodiment of the present invention, the output compensation in step S1 is determined by an event triggering mechanism, and the method includes:

[0017] Define event triggering error;

[0018] defining an event trigger condition according to the event trigger error;

[0019] Output compensation is designed according to the event triggering condition, and the sliding mode controller is compensated by the output compensation.

[0020] In one embodiment of the present invention, the formula for the event trigger error is:

[0021] e1(k)=y1(k)-y(k)

[0022] Among them, y1(k) is the last data successfully transmitted to the controller, and y(k) is the output data transmitted at time k;

[0023] The formula for the event triggering condition is:

[0024]

[0025] in, is the threshold for event triggering,

[0026] The output compensation formula is:

[0027]

[0028] in, As output compensation for transmission failure.

[0029] In one embodiment of the present invention, according to the output compensation of the transmission failure, the output compensation formula is rewritten as:

[0030]

[0031] Among them, p(k)=0 indicates that the event triggering condition is not met, p(k)=1 indicates that the event triggering condition is met, q(k)=0 indicates that the output transmission of the unmanned surface vehicle fails, and q(k)=1 indicates that the output transmission of the unmanned surface vehicle is successful.

[0032] In one embodiment of the present invention, after constructing the model-free sliding mode controller with output compensation in step S1, the model-free sliding mode controller also includes sending a control input signal to the actuator through a communication network, and the actuator is used to control the heading of the unmanned surface vehicle according to the received control input signal. If the actuator receives the control input signal u(k) of the model-free sliding mode controller at time k, then k=G d , where G d ∈Z + , d=1,2,...;

[0033] For the data loss time k∈(G d ,G d+1 ) control input data is lost, input compensation is performed, the formula is:

[0034] u(k)=u(G d + b) = u(G d +b-1)+μ b Δu(G d )

[0035] Among them, μ∈(0,1] is the compensation coefficient, b∈Z + .

[0036] In order to solve the above technical problems, the present invention provides a heading control system for an unmanned surface vehicle in the case of data loss, comprising:

[0037] A construction module: used to construct a model-free sliding mode controller with output compensation, wherein the output compensation is determined by an event triggering mechanism;

[0038] Heading module: used to realize the heading control of the unmanned surface vehicle through the model-free sliding mode controller with output compensation.

[0039] In order to solve the above technical problems, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the heading control method of an unmanned surface vehicle in the above-mentioned data loss situation are implemented.

[0040] To solve the above technical problems, the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method for heading control of an unmanned surface vehicle in the above data loss situation are implemented.

[0041] The above technical solution of the present invention has the following advantages compared with the prior art:

[0042] The method for controlling the heading of an unmanned surface vehicle under data loss conditions of the present invention designs a model-free sliding mode controller, through which the heading of the unmanned surface vehicle can be effectively controlled; and the present invention can perform output compensation on the controller and input compensation on the actuator, and the adverse effects of data loss can be effectively reduced through output compensation and input compensation;

[0043] The event-triggered communication mechanism of the present invention can determine when to transmit the collected unmanned surface vehicle data to the controller when controlling the unmanned surface vehicle, thereby saving the number of communications and effectively solving the communication resource problem;

[0044] The present invention has higher heading control accuracy and can be widely used in practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0046] Figure 1 is a flow chart of the method of the present invention;

[0047] Figure 2 is a principle block diagram of a method for controlling the heading of an unmanned surface vehicle in an embodiment of the present invention;

[0048] Figure 3 It is a schematic diagram of data loss, event triggering interval, and output of different methods in the case of the first target heading in an embodiment of the present invention;

[0049] Figure 4 It is a schematic diagram of data loss, event triggering interval, and output of different methods in the case of a second target heading in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0051] Embodiment 1

[0052] Reference Figure 1 The present invention relates to a heading control method for an unmanned surface vehicle in the case of data loss, comprising:

[0053] Step S1: constructing a model-free sliding mode controller with output compensation, wherein the output compensation is determined by an event triggering mechanism;

[0054] Step S2: Implementing heading control of the unmanned surface vehicle through the model-free sliding mode controller with output compensation.

[0055] The following is a detailed introduction to this embodiment:

[0056] This embodiment can effectively control the heading of the unmanned surface vehicle by studying and redefining the design of output control, event triggering mechanism, and input and output compensation mechanism, including:

[0057] First aspect: This embodiment designs a model-free sliding mode controller, and the controller is described as follows:

[0058]

[0059] in, λ is a constant, β is a constant greater than 0, y d (k+1) is the expected output at time k+1, k is the time, y2(k) is the output compensation, is a pseudo partial derivative and satisfies:

[0060]

[0061] Its reset mechanism is:

[0062]

[0063] Among them, α∈(0,1], θ>0, Δu(k-1) is u(k-1)-u(k-2), is a very small positive number, and yes The initial value of; sign() is the sign function.

[0064] It should be noted that the above formula (2) and formula (3) reflect that the method of this embodiment incorporates the MFAC method.

[0065] Second aspect: please refer to Figure 2 ,This embodiment designs input compensation and output compensation strategies.

[0066] (I) Output compensation is as follows:

[0067] Define the event trigger error as:

[0068] e1(k)=y1(k)-y(k) (4)

[0069] Among them, y1(k) is the last data successfully transmitted to the controller, and y(k) is the output data transmitted at time k.

[0070] The event triggering conditions (i.e. event triggering mechanism) are defined as:

[0071]

[0072] in, is the threshold for event triggering,

[0073] It should be noted that when the present embodiment performs heading control on the unmanned surface vehicle, the heading data of the unmanned surface vehicle is collected by sensors, and the collected heading data is sent to the cloud controller through the communication network. Whether the relevant data is sent to the cloud controller through the communication network is determined by an event trigger mechanism. The reason why the present embodiment introduces the event trigger mechanism is that it can reduce the number of times the heading data is sent and effectively save communication resources.

[0074] Based on the event trigger mechanism, the output compensation strategy designed in this embodiment is as follows:

[0075]

[0076] in, As transmission failure output compensation.

[0077] Furthermore, according to the output compensation of transmission failure, this embodiment rewrites the output compensation formula (6) as follows:

[0078]

[0079] Among them, p(k)=0 indicates that the event triggering condition is not met, p(k)=1 indicates that the event triggering condition is met, q(k)=0 indicates that the output transmission of the unmanned surface vehicle fails, and q(k)=1 indicates that the output transmission of the unmanned surface vehicle is successful.

[0080] (II) Input compensation is as follows:

[0081] The controller of this embodiment sends a control input signal to the actuator through the communication network, and the actuator is used to control the heading of the unmanned surface vehicle according to the received control input signal. If the actuator successfully receives u(k) at time k, then k = G d , where G d ∈Z + , d=1,2,...。

[0082] For the data loss time k∈(G d ,G d+1 ), that is, the control input signal of the controller is not successfully sent to the actuator, so there is a loss of control input data (for example: assuming 10 seconds as the signal acquisition cycle, assuming G d At the first second, u(k) is successfully received, and assuming that G d+1 At the 7th second, u(k) is successfully received again, which means that all the moments between the 1st and 7th seconds, that is, k∈(G d ,G d+1 ) both have data loss), then input compensation is performed, and the input compensation scheme is designed as follows:

[0083] u(k)=u(G d + b) = u(G d +b-1)+μ b Δu(G d ) (8)

[0084] Among them, μ∈(0,1] is the compensation coefficient, b∈Z + .

[0085] Furthermore, the output compensation strategy is based on an event trigger mechanism. The control output is updated.

[0086] Furthermore, the above control scheme and compensation method are applied to control the unmanned surface vehicle to perform |y d (k+1)-y d (k)|<F, where F∈Z + , there exists λβ>1 so that the tracking error is bounded.

[0087] This embodiment also verifies whether the controller is valid, as follows:

[0088] First, the sliding surface is designed as:

[0089]

[0090] Define the system output error e(k) as follows:

[0091] e(k)=y d (k)-y(k) (10)

[0092] According to the above method of the present invention, based on the compensation strategy and the controller designed in this embodiment, it is obtained:

[0093] e(k+1)=e(k)-Δy(k+1)+Δy d (k+1)

[0094] =e(k)-ψ(k)Δu(k)+Δy d (k+1)

[0095] =e(G d )-ψ(G d )Δu(G d )-ψ(G d +1)×Δu(G d +1)-...-ψ(k)Δu(k)+Δy d (k+1)(11)

[0096] According to the compensation strategy, we can get:

[0097]

[0098] Substituting formula (12) into formula (11):

[0099]

[0100] in,

[0101]

[0102] From the boundedness of ψ(k), we know that:

[0103]

[0104]

[0105]

[0106] If λβ>2, then it is necessary to satisfy If 1<λβ<2, then it needs to satisfy From this we can see that 0<s(kG d )<1, let s(kG d ) is bounded by s low , the upper bound is s up Similarly, 0<h(kG d )<1, let h(kG d ) has a lower bound of h low , the upper bound is h up .

[0107] Take the absolute value of both sides of formula (11),

[0108]

[0109] The data loss follows a Bernoulli distribution. and in Apparently are bounded. Therefore Where M and N are positive real numbers. We can get:

[0110]

[0111] From the above formula, we can see that the expectation of the absolute value of the system output error is bounded and the expectation of the output error is convergent.

[0112] Therefore, it is proved that under the control of the controller provided by formula (1), e(k) = y d (k)-y(k) is convergent, indicating that the controller designed in this embodiment is effective.

[0113] The following is a description of the actual work of the unmanned surface vehicle:

[0114] This embodiment builds a small USV experimental platform, and the main parameters are designed as follows: θ = 0.6, T=10 -6 , μ=0.2,λ=0.9,β=3,y(1)=0,ψ(1)=4,K=0.186,T=1.068,K1=22. Packet loss probability in the forward and feedback channels.

[0115] Working situation 1:

[0116] Set the target heading to y d (k) = 80. Figure 3 In (a) (data loss case), “1” and “0” represent successful and failed data transmission, respectively, and the two curves represent the packet loss frequency of the two channels. Figure 3 In (b) (time trigger interval), we can see that the event trigger mechanism is effective and minimizes the waste of communication resources. Out of 500 times, the event was triggered 218 times, saving 56.4% of energy. Figure 3 In (c) (output of different methods), the proposed model-free sliding mode control has a faster convergence speed in compensation strategy than the existing method. This method converges to the target curve y when k = 20. d (k)=80, while the existing method uses k=60.

[0117] Working situation 2:

[0118] Set the target heading to yd (k+1)=0.3sin(kπ / 300). The method proposed in the present invention is still effective for time-varying systems. Figure 4 (a) (data loss scenario) shows the data loss scenario. The probability of data loss still remains at 50%. Figure 4 (b) (Time Trigger Interval) shows the instant when the event is triggered and the corresponding trigger interval, where the height of each point represents the time difference between the current trigger instant and the previous trigger instant. Out of 1000 times, the event was triggered 875 times, saving 12.5% ​​of energy. Figure 4 In (c) (output of different methods), the proposed method shows more small errors, smoother curves and reduced oscillations compared to the existing method, indicating its superior performance. Between k = 766 and k = 770, the existing method has errors and jitters, while the proposed method has a smoother and more accurate tracking curve.

[0119] Embodiment 2

[0120] This embodiment provides a heading control system for an unmanned surface vehicle in the event of data loss, including:

[0121] A construction module: used to construct a model-free sliding mode controller with output compensation, wherein the output compensation is determined by an event triggering mechanism;

[0122] Heading module: used to realize the heading control of the unmanned surface vehicle through the model-free sliding mode controller with output compensation.

[0123] Embodiment 3

[0124] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for heading control of an unmanned surface vehicle in the event of data loss described in Embodiment 1 are implemented.

[0125] Embodiment 4

[0126] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method for heading control of an unmanned surface vehicle in the event of data loss described in the first embodiment are implemented.

[0127] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0128] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0129] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0130] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0131] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0132] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for controlling the heading of an unmanned surface vehicle in the event of data loss, characterized in that: include: Step S1: Construct a model-free sliding mode controller with output compensation, the formula is: in, λ is a constant, β is a constant greater than 0, y d (k+1) is the expected output, k is the time, y2(k) is the output compensation, is the pseudo partial derivative; The pseudo partial derivative It is expressed as: Among them, α∈(0,1], θ>0, Δu(k-1) is u(k-1)-u(k-2); The pseudo partial derivative The reset mechanism formula is: in, is a positive number, yes The initial value of, sign() is the sign function Wherein, the output compensation is determined by an event triggering mechanism, and the method includes: Define event triggering error; defining an event trigger condition according to the event trigger error; Designing output compensation according to the event triggering condition, and compensating the sliding mode controller by the output compensation; The formula for the event trigger error is: e1(k)=y1(k)-y(k) Among them, y1(k) is the last data successfully transmitted to the controller, and y(k) is the output data transmitted at time k; The formula for the event triggering condition is: in, is the threshold for event triggering, The output compensation formula is: in, As output compensation for transmission failure; Step S2: Implementing heading control of the unmanned surface vehicle through the model-free sliding mode controller with output compensation.

2. The method for controlling the heading of an unmanned surface vehicle in the event of data loss according to claim 1, characterized in that: According to the output compensation of the transmission failure, the output compensation formula is rewritten as: Among them, p(k)=0 indicates that the event triggering condition is not met, p(k)=1 indicates that the event triggering condition is met, q(k)=0 indicates that the output transmission of the unmanned surface vehicle fails, and q(k)=1 indicates that the output transmission of the unmanned surface vehicle is successful.

3. The method for controlling the heading of an unmanned surface vehicle in the event of data loss according to claim 1, characterized in that: After the model-free sliding mode controller with output compensation is constructed in step S1, the model-free sliding mode controller sends a control input signal to the actuator through a communication network, and the actuator is used to control the heading of the unmanned surface vehicle according to the received control input signal. If the actuator receives the control input signal u(k) of the model-free sliding mode controller at time k, then k=G d , where G d ∈Z + , d=1,2,...; For the data loss time k∈(G d ,G d+1 ) control input data is lost, input compensation is performed, the formula is: u(k)=u(G d +b)=u(G d +b-1)+μ b Δu(G d ) Among them, μ∈(0,1] is the compensation coefficient, b∈Z + .

4. A heading control system for an unmanned surface vehicle in the case of data loss, used to implement the heading control method for an unmanned surface vehicle in the case of data loss as claimed in any one of claims 1 to 3, characterized in that: include: A construction module: used to construct a model-free sliding mode controller with output compensation, wherein the output compensation is determined by an event triggering mechanism; Heading module: used to realize the heading control of the unmanned surface vehicle through the model-free sliding mode controller with output compensation.

5. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method for heading control of an unmanned surface vehicle in the event of data loss as described in any one of claims 1 to 3 are implemented.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for heading control of an unmanned surface vehicle in the event of data loss as claimed in any one of claims 1 to 3 are implemented.

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