Underwater robot model-free adaptive trajectory tracking control method and system, underwater robot and storage medium

Abstract

The invention provides a model-free adaptive trajectory tracking control method and system for an underwater robot, the underwater robot and a storage medium. The method comprises the following steps: acquiring a reference path, and discretizing the reference path to obtain a target position; obtaining a target speed according to the parameters such as the first moment position and the target position, smoothing the target speed to obtain an estimated target speed, obtaining a target acceleration according to the parameters such as the first moment speed, and substituting the parameters such as the difference of the first moment acceleration into a first target function to obtain an estimated pseudo Jacobian matrix; and parameters such as the estimated pseudo Jacobian matrix and the target acceleration are substituted into a second target function to obtain a first moment resultant force and moment, the underwater robot operates according to the first moment resultant force and moment, the first moment speed and the first moment acceleration are updated, and the steps are repeated. The inertia influence is reduced, the dynamic response of the system is quicker, and the control precision and the system stability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of robot control, and particularly relates to a model-free adaptive trajectory tracking control method and system for an underwater robot, an underwater robot, and a storage medium. Background Art

[0002] Unmanned Underwater Vehicles (UUVs) are widely used in fields such as seabed exploration, environmental monitoring, and resource exploration. Traditional UUV trajectory tracking control methods, such as PID control, fuzzy control, and sliding mode control, have many deficiencies. Especially in complex underwater environments, the nonlinearity and uncertainty of the system affect the control accuracy. With the complication of the underwater operation environment, the deficiencies of traditional control methods in terms of response speed, adaptability, and accuracy are gradually exposed. Therefore, developing a model-independent control method to improve the trajectory tracking accuracy of UUVs in complex environments has become an urgent problem to be solved.

[0003] In the prior art, a model-free adaptive control method that maps from the position layer to the velocity layer is commonly used, and this method is also independent of the UUV model. However, during the UUV velocity control process, especially when the acceleration is large, the system is still prone to integral effects, resulting in a change in the sign relationship between the control variable and the controlled variable. The partial derivative needs to be continuously reset, which further has an adverse effect on the control performance. Summary of the Invention

[0004] The present invention is made to solve the above problems, and aims to provide a model-free adaptive trajectory tracking control method and system for an underwater robot, an underwater robot, and a storage medium.

[0005] The present invention provides a model-free adaptive trajectory tracking control method for an underwater robot, which has the following characteristics: including: Step S1, obtaining a reference path and discretizing the reference path to obtain target positions; Step S2, obtaining a target velocity according to the position at the first moment, the position at the second moment, the velocity at the first moment, and the target positions, and smoothing the target velocity through a differential tracker according to the target velocity at the first moment and the estimated target velocity at the first moment to obtain an estimated target velocity; Step S3, obtaining a target acceleration according to the velocity at the first moment, the acceleration at the first moment, the estimated target velocity, and the differential term of the estimated target velocity through a second PD controller; Step S4, substituting the difference of the acceleration at the first moment and the difference of the resultant force and moment at the third moment into a first objective function to obtain an estimated pseudo-Jacobian matrix; Step S5, substituting the estimated pseudo-Jacobian matrix, the resultant force and moment at the third moment, the acceleration at the first moment, and the target acceleration into a second objective function to obtain the resultant force and moment at the first moment; Step S6, the underwater robot operates according to the resultant force and moment at the first moment, updates the velocity at the first moment and the acceleration at the first moment according to the operation result, and then repeats Steps S2 to S6 for iteration.

[0006] In the model-free adaptive trajectory tracking control method for an underwater robot provided by the present invention, it may also have the following characteristics: wherein, Step S2 includes the following sub-steps: Step S201, obtaining a nominal velocity according to the target position and the position at the second moment, and the nominal velocity is obtained according to the following formula:

[0007]

[0008] In the formula, is the nominal velocity, η d (k + 1) is the target position, η(k + 1) is the position at the second moment, is the differential of the target position; Step S202, obtaining a target velocity according to the target position, the nominal velocity, the position at the first moment, and the velocity at the first moment, and the target velocity is obtained according to the following formula:

[0009]

[0010] In the formula, v d (k + 1) is the target velocity, η(k) is the position at the first moment, v(k) is the velocity at the first moment; Step S203, obtaining an estimated target velocity according to the velocity at the first moment and the estimated velocity at the first moment, and the estimated target velocity is obtained according to the following formula:

[0011]

[0012] In the formula, r is a fast factor, h0 is a filtering factor, h is a step size, v d (k) is the target velocity at the first moment, Estimate the target velocity at the first moment, Estimate the target velocity at the second moment, Is the differential of the estimated target velocity at the second moment.

[0013] In the model-free adaptive trajectory tracking control method for an underwater robot provided by the present invention, it may further have the following characteristics: Among them, the formula for obtaining the target acceleration according to the velocity at the first moment, the acceleration at the first moment, the estimated target velocity, and the differential term of the estimated target velocity through the second PD controller is:

[0014]

[0015] In the formula, a d (k + 1) is the target acceleration, Is the differential of the estimated target velocity at the second moment, Is the estimated target velocity at the second moment, ν(k) is the velocity at the first moment, and a(k) is the acceleration at the first moment.

[0016] In the model-free adaptive trajectory tracking control method for an underwater robot provided by the present invention, it may further have the following characteristics: Among them, in step S4, substituting the difference of the acceleration at the first moment and the difference of the resultant force and moment at the third moment into the first objective function to obtain the formula for the estimated pseudo-Jacobian matrix is:

[0017]

[0018]

[0019] In the formula, Δa(k) is the difference of the acceleration at the first moment, Δτ(k - 1) is the difference of the resultant force and moment at the third moment, η is the first step factor and η ∈ (0, 2), μ is the penalty factor, Φ(k) is the pseudo-Jacobian matrix of the pseudo-dynamic model Δa(k) = Φ(k)Δτ(k - 1), Is the estimated pseudo-Jacobian matrix, Is the estimated pseudo-Jacobian matrix at the third moment.

[0020] In the model-free adaptive trajectory tracking control method for an underwater robot provided by the present invention, it may further have the following characteristics: Among them,

[0021] In step S5, substituting the estimated pseudo-Jacobian matrix, the resultant force and moment at the third moment, the acceleration at the first moment, and the target acceleration into the second objective function to obtain the formula for the resultant force and moment at the first moment is:

[0022] J(τ(k)) = ‖a d (k + 1) - a(k)‖ 2 + λ‖τ(k) - τ(k - 1)‖2

[0023]

[0024] wherein, a d (k + 1) is the target acceleration, a(k) is the acceleration at the first moment, is the estimated pseudo-Jacobian matrix, τ(k - 1) is the resultant force and moment at the third moment, τ(k) is the resultant force and moment at the first moment, ρ is the second step factor, λ is the weight coefficient, and λ > 0.

[0025] In the model-free adaptive trajectory tracking control method for an underwater robot provided by the present invention, it may further have the following feature: when a disturbance occurs in the control system, the estimated pseudo-Jacobian matrix is adjusted to adapt to the new system state. The formula for adjusting the estimated pseudo-Jacobian matrix is:

[0026]

[0027] wherein, α ∈ (0, 1), b1 and b2 are constants, is the main diagonal element of the estimated pseudo-Jacobian matrix, is the estimated pseudo-Jacobian matrix of the i-th row and j-th column element.

[0028] In the model-free adaptive trajectory tracking control method for an underwater robot provided by the present invention, it may further have the following feature: wherein, the first moment is the current moment, the second moment is the next moment after the first moment, and the third moment is the moment before the first moment.

[0029] The present invention provides a model-free adaptive trajectory tracking control system for an underwater robot, which has the following features: a discrete module for obtaining a reference path and discretizing the reference path to obtain target positions; a target speed generation module for obtaining a target speed by using the position at the first moment, the position at the second moment, the speed at the first moment, and the target positions and through a first PD controller, smoothing the target speed by using the target speed at the first moment and the estimated target speed at the first moment and through a differential tracker to obtain an estimated target speed; a target acceleration generation module for obtaining a target acceleration by using the speed at the first moment, the acceleration at the first moment, the estimated target speed, and the differential term of the estimated target speed and through a second PD controller; a pseudo-Jacobian matrix calculation module for substituting the difference of the acceleration at the first moment and the difference of the resultant force and torque at the third moment into a first objective function to obtain an estimated pseudo-Jacobian matrix; a resultant force and torque calculation module for substituting the estimated pseudo-Jacobian matrix, the resultant force and torque at the third moment, the acceleration at the first moment, and the target acceleration into a second objective function to obtain the resultant force and torque at the first moment; and an update module for the underwater robot to operate according to the resultant force and torque at the first moment, for updating the speed at the first moment and the acceleration at the first moment, and repeating the above operations for iteration.

[0030] The present invention provides an underwater robot, including a memory, a processor, and a computer program stored on the memory and executable on the processor, which has the following features: when the processor executes the computer program, the model-free adaptive trajectory tracking control method for the underwater robot according to any one of the above is implemented.

[0031] The present invention provides a storage medium, on which a computer program is stored, which has the following features: when the computer program is executed by a processor, the model-free adaptive trajectory tracking control method for the underwater robot according to any one of the above is implemented.

[0032] Functions and effects of the invention

[0033] According to the model-free adaptive trajectory tracking control method and system for an underwater robot, the underwater robot, and the storage medium according to the present invention, because in step S1, a reference path is acquired, and the reference path is discretized to obtain target positions; in step S2, according to the position at the first moment, the position at the second moment, the velocity at the first moment, and the target positions, and through a first PD controller, a target velocity is obtained. According to the target velocity at the first moment and the estimated target velocity at the first moment, and through a differential tracker, the target velocity is smoothed to obtain an estimated target velocity; in step S3, according to the velocity at the first moment, the acceleration at the first moment, the estimated target velocity, and the differential term of the estimated target velocity, and through a second PD controller, a target acceleration is obtained; in step S4, the difference of the acceleration at the first moment and the difference of the resultant force and moment at the third moment are substituted into a first objective function to obtain an estimated pseudo-Jacobian matrix; in step S5, the estimated pseudo-Jacobian matrix, the resultant force and moment at the third moment, the acceleration at the first moment, and the target acceleration are substituted into a second objective function to obtain the resultant force and moment at the first moment; in step S6, the underwater robot operates according to the resultant force and moment at the first moment, and according to the operation result, the velocity at the first moment and the acceleration at the first moment are updated, and then steps S2 to S6 are repeated for iteration. Therefore, the model-free adaptive trajectory tracking control method and system for an underwater robot, the underwater robot, and the storage medium according to the present invention do not rely on a model, and by directly controlling the acceleration, the inertial influence is reduced, the dynamic response of the system is made more rapid, and the control accuracy and system stability are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 FIG. is a schematic flow chart of the model-free adaptive trajectory tracking control method for an underwater robot in an embodiment of the present invention.

[0035] Figure 2 FIG. is a flow block diagram of the model-free adaptive trajectory tracking control method for an underwater robot in an embodiment of the present invention.

[0036] Figure 3 FIG. is a schematic module diagram of the model-free adaptive trajectory tracking control system for an underwater robot in an embodiment of the present invention.

[0037] Figure 4 FIG. is a schematic structural diagram of an underwater robot in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0039] In order to make the technical means, creative features, achieved objectives, and functions of the present invention easy to understand, the following embodiments will specifically elaborate on the model-free adaptive trajectory tracking control method and system for an underwater robot, the underwater robot, and the storage medium of the present invention in conjunction with the accompanying drawings.

[0040] Embodiment

[0041] Figure 1 is a schematic flowchart of the model-free adaptive trajectory tracking control method for an underwater robot in the embodiments of the present invention.

[0042] Figure 2 is a flowchart block diagram of the model-free adaptive trajectory tracking control method for an underwater robot in the embodiments of the present invention.

[0043] As Figure 1 and Figure 2 shown, the model-free adaptive trajectory tracking control method for an underwater robot specifically includes the following steps:

[0044] Step S1, obtain a reference path and discretize the reference path to obtain target positions.

[0045] Among them, the target positions are a discrete set of points.

[0046] Step S2, obtain a target velocity according to the position at the first moment, the position at the second moment, the velocity at the first moment, and the target positions, and through a first PD controller. According to the target velocity at the first moment and the estimated target velocity at the first moment, and through a Tracking Differentiator, smooth the target velocity to obtain an estimated target velocity. Among them, the first moment is the current moment, the second moment is the moment after the first moment, and the third moment is the moment before the first moment.

[0047] Among them, step S2 includes the following sub-steps:

[0048] Step S201, obtain a nominal velocity according to the target positions and the position at the second moment. The nominal velocity is obtained according to the following formula:

[0049]

[0050] In the formula, is the nominal speed, η d (k + 1) is the target position, η(k + 1) is the position at the second moment, is the differential of the target position.

[0051] Step S202: Obtain the target speed based on the target position, nominal speed, position at the first moment, and speed at the first moment. The target speed is obtained according to the following formula:

[0052]

[0053] In the formula, v d (k + 1) is the target speed, η(k) is the position at the first moment, and v(k) is the speed at the first moment.

[0054] Step S201 and step S202 output the signal of the target speed through the first PD controller.

[0055] Step S203: Obtain the estimated target speed based on the speed at the first moment and the estimated speed at the first moment. The estimated target speed is obtained according to the following formula:

[0056]

[0057]

[0058] In the formula, r is the fast factor, h0 is the filtering factor, h is the step size, v d (k) is the target speed at the first moment, is the estimated target speed at the first moment, is the estimated target speed at the second moment, is the differential of the estimated target speed at the second moment.

[0059] Among them, the response speed of tracking and noise suppression are determined by controlling the values of r and h0.

[0060] Step S3: Obtain the target acceleration based on the speed at the first moment, acceleration at the first moment, estimated target speed, and the differential term of the estimated target speed through the second PD controller.

[0061] Among them, the formula for obtaining the target acceleration based on the speed at the first moment, acceleration at the first moment, estimated target speed, and the differential term of the estimated target speed through the second PD controller is:

[0062]

[0063] In the formula, a d (k + 1) is the target acceleration, is the differential of the estimated target velocity at the second moment, is the estimated target velocity at the second moment, v(k) is the velocity at the first moment, and a(k) is the acceleration at the first moment.

[0064] Steps S1 - S3 are the outer - loop control process, which generates the required target acceleration and inputs the target acceleration into the MFAC module (Model - Free Adaptive Control).

[0065] In step S4, substitute the difference of the acceleration at the first moment and the difference of the resultant force and torque at the third moment into the first objective function to obtain the estimated pseudo - Jacobian matrix.

[0066] Among them, the formula for substituting the difference of the acceleration at the first moment and the difference of the resultant force and torque at the third moment into the first objective function to obtain the estimated pseudo - Jacobian matrix in step S4 is:

[0067]

[0068]

[0069] In the formula, Δa(k) is the difference of the acceleration at the first moment, Δτ(k - 1) is the difference of the resultant force and torque at the third moment, η is the first step - size factor and η∈(0, 2), μ is the penalty factor, Φ(k) is the pseudo - Jacobian matrix of the pseudo - dynamic model Δa(k)=Φ(k)Δτ(k - 1), is the estimated pseudo - Jacobian matrix, is the estimated pseudo - Jacobian matrix at the third moment.

[0070] Among them, ||Δa(k)-Φ(k)Δτ(k - 1)|| 2 is the fitting term, which forces the estimated value to match Δa(k), is the regularization term, which ensures the smoothness and stability of the estimation process, prevents over - fitting and mutations. μ is the penalty factor, which controls the weight of this term and updates the parameters recursively.

[0071] In step S5, substitute the estimated pseudo - Jacobian matrix, the resultant force and torque at the third moment, the acceleration at the first moment, and the target acceleration into the second objective function to obtain the resultant force and torque at the first moment.

[0072] The formula for substituting the estimated pseudo - Jacobian matrix, the resultant force and torque at the third moment, the acceleration at the first moment, and the target acceleration into the second objective function to obtain the resultant force and torque at the first moment in step S5 is:

[0073] J(τ(k))=‖a d (k + 1)-a(k)‖ 2 +λ‖τ(k)-τ(k - 1)‖ 2

[0074]

[0075] where a d (k + 1) is the target acceleration, a(k) is the acceleration at the first moment, is the estimated pseudo-Jacobian matrix, representing the sensitivity of a(k) to τ, τ(k - 1) is the resultant force and moment at the third moment, τ(k) is the resultant force and moment at the first moment, ρ is the second step factor, λ is the weight coefficient, and λ > 0.

[0076] Step S6, the underwater robot operates according to the resultant force and moment at the first moment, thereby updating the velocity and acceleration at the first moment, and repeating steps S2 - S6 for iteration.

[0077] Steps S4 - S6 are the inner loop control process, which tracks the signal to achieve precise trajectory control. After the underwater robot operates according to the resultant force and moment at the first moment, the velocity, acceleration, and its own position at the new moment are generated, and respectively replace the corresponding velocity, acceleration, and its own position at the previous moment. The target acceleration at the new moment is obtained through the outer loop control process, and the inner loop control is performed based on the target acceleration at the new moment, thereby continuously iterating.

[0078] In the model - free adaptive trajectory tracking control method for the underwater robot provided in this embodiment, it further includes: when the control system is disturbed, adjusting the estimated pseudo - Jacobian matrix to adapt to the new system state. The formula for adjusting the estimated pseudo - Jacobian matrix is:

[0079]

[0080] where α ∈ (0, 1), b1, b2 are constants, is the main diagonal element of the estimated pseudo - Jacobian matrix, is the estimated pseudo - Jacobian matrix of the i - th row and j - th column element.

[0081] Figure 3 is the schematic diagram of the module of the model - free adaptive trajectory tracking control system for the underwater robot in the embodiment of the present invention.

[0082] As Figure 3 shown, this embodiment provides a model - free adaptive trajectory tracking control system for an underwater robot, including: a discretization module 301, a target velocity generation module 302, a target acceleration generation module 303, a pseudo - Jacobian matrix calculation module 304, a resultant force and moment calculation module 305, and an update module 306.

[0083] The discretization module 301 is used to adopt the above - mentioned step S1 to obtain the reference path and discretize the reference path to obtain the target position.

[0084] The target speed generation module 302 is configured to use the above-mentioned step S2 to obtain the target speed according to the position at the first moment, the position at the second moment, the speed at the first moment, and the target position through the first PD controller, and smooth the target speed according to the target speed at the first moment and the estimated target speed at the first moment through a differential tracker to obtain the estimated target speed.

[0085] The target acceleration generation module 303 is configured to use the above-mentioned step S3 to obtain the target acceleration according to the speed at the first moment, the acceleration at the first moment, the estimated target speed, and the differential term of the estimated target speed through the second PD controller.

[0086] The pseudo-Jacobian matrix calculation module 304 is configured to use the above-mentioned step S4 to substitute the difference of the acceleration at the first moment and the difference of the resultant force and torque at the third moment into the first objective function to obtain the estimated pseudo-Jacobian matrix.

[0087] The resultant force and torque calculation module 305 is configured to use the above-mentioned step S5 to substitute the estimated pseudo-Jacobian matrix, the resultant force and torque at the third moment, the acceleration at the first moment, and the target acceleration into the second objective function to obtain the resultant force and torque at the first moment.

[0088] The update module 306 is configured to use the above-mentioned step S6 for the underwater robot to operate according to the resultant force and torque at the first moment, and is used to update the speed and acceleration at the first moment according to the operation result, and then repeat the above operations for iteration.

[0089] Figure 4 FIG. 18 is a schematic structural diagram of an underwater robot in an embodiment of the present invention, showing a block diagram of an exemplary underwater robot 40 suitable for implementing the embodiments of the present invention. Figure 4 The shown underwater robot 40 is only an example and should not impose any limitation on the functions and the scope of use of the embodiments of the present invention.

[0090] As Figure 4 shown, the underwater robot 40 may be presented in the form of a general-purpose computing device, for example, it may be a server device. The components of the underwater robot 40 may include, but are not limited to: at least one of the above-mentioned processors 41, at least one of the above-mentioned memories 42, and a bus 43 connecting different system components (including the memory 42 and the processor 41).

[0091] The bus 43 includes a data bus, an address bus, and a control bus.

[0092] The memory 42 may include volatile memory, such as a random access memory (RAM) 421 and / or a cache memory 422, and may further include a read-only memory (ROM) 423.

[0093] The memory 42 may also include a program tool 425 (or utility) having a set (at least one) of program modules 424. Such program modules 424 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data. Each of these examples or some combination thereof may include the implementation of a network environment.

[0094] The processor 41 executes various functional applications and data processing by running computer programs stored in the memory 42, such as the methods provided in any of the above embodiments.

[0095] The underwater robot 40 can also communicate with one or more external devices 44 (such as a keyboard, a pointing device, etc.). Such communication can be carried out through the input / output (I / O) interface 45. Moreover, the model-generated underwater robot 40 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through the network adapter 46. As shown in the figure, the network adapter 46 communicates with other modules of the model-generated underwater robot 40 through the bus 43. It should be understood that although not shown in the figure, other hardware and / or software modules can be used in combination with the model-generated underwater robot 40, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems, etc.

[0096] An embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the method provided in any of the above embodiments is implemented.

[0097] Among them, the more specific forms that the readable storage medium can adopt include, but are not limited to: portable disks, hard disks, random access memories, read-only memories, erasable programmable read-only memories, optical storage devices, magnetic storage devices, or any suitable combination of the above.

[0098] In a possible implementation manner, an embodiment of the present invention can also be implemented in the form of a program product, which includes program code. When the program product runs on a terminal device, the program code is used to cause the terminal device to execute the method implemented in any of the above embodiments.

[0099] Among them, the program code for executing the present invention can be written in any combination of one or more programming languages. The program code can be executed entirely on the user device, partially on the user device, executed as an independent software package, partially on the user device and partially on a remote device, or entirely on a remote device.

[0100] Functions and effects of the embodiment

[0101] According to the model-free adaptive trajectory tracking control method and system for an underwater robot, the underwater robot, and the storage medium according to the present invention, because in step S1, a reference path is acquired, and the reference path is discretized to obtain target positions; in step S2, according to the position at the first moment, the position at the second moment, the velocity at the first moment, and the target positions, and through a first PD controller, a target velocity is obtained. According to the target velocity at the first moment and the estimated target velocity at the first moment, and through a differentiator, the target velocity is smoothed to obtain an estimated target velocity; in step S3, according to the velocity at the first moment, the acceleration at the first moment, the estimated target velocity, and the differential term of the estimated target velocity, and through a second PD controller, a target acceleration is obtained; in step S4, the difference of the acceleration at the first moment and the difference of the resultant force and moment at the third moment are substituted into a first objective function to obtain an estimated pseudo-Jacobian matrix; in step S5, the estimated pseudo-Jacobian matrix, the resultant force and moment at the third moment, the acceleration at the first moment, and the target acceleration are substituted into a second objective function to obtain the resultant force and moment at the first moment; in step S6, the underwater robot operates according to the resultant force and moment at the first moment, thereby updating the velocity at the first moment and the acceleration at the first moment, and steps S2 - S6 are repeated for iteration. Therefore, the model-free adaptive trajectory tracking control method and system for an underwater robot, the underwater robot, and the storage medium according to the present invention do not rely on a model. By directly controlling the acceleration, the inertial influence is reduced, the dynamic response of the system is made more rapid, and the control accuracy and system stability are improved.

[0102] In this embodiment, a differentiator is used, which can achieve a smooth transition of the target acceleration, reduce the fluctuations in the control process, and thus improve the stability of the control system.

[0103] In this embodiment, when a large disturbance occurs in the system, by recalculating and adjusting the pseudo-Jacobian matrix, the control system can quickly adapt to new environmental changes or system states.

[0104] Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. An underwater robot model-free adaptive trajectory tracking control method, characterized in that Including: Step S1: Obtain a reference path and discretize the reference path to obtain target positions; Step S2: Obtain a target velocity based on the position at the first moment, the position at the second moment, the velocity at the first moment, and the target positions, and smooth the target velocity through a differential tracker based on the target velocity at the first moment and the estimated target velocity at the first moment to obtain an estimated target velocity; Step S3: Obtain a target acceleration based on the velocity at the first moment, the acceleration at the first moment, the estimated target velocity, and the differential term of the estimated target velocity through a second PD controller; Step S4: Substitute the difference in acceleration at the first moment and the difference in the resultant force and moment at the third moment into a first objective function to obtain an estimated pseudo-Jacobian matrix; Step S5: Substitute the estimated pseudo-Jacobian matrix, the resultant force and moment at the third moment, the acceleration at the first moment, and the target acceleration into a second objective function to obtain the resultant force and moment at the first moment; Step S6: The underwater robot operates according to the resultant force and moment at the first moment, updates the velocity and acceleration at the first moment based on the operation results, and then repeats Steps S2 to S6 for iteration.

2. The model-free adaptive trajectory tracking control method for an underwater robot according to claim 1, Characterized in that: Among them, Step S2 includes the following sub-steps: Step S201: Obtain a nominal velocity based on the target positions and the position at the second moment, and the nominal velocity is obtained according to the following formula: In the formula, is the nominal speed, and η d (k + 1) is the target position, η(k + 1) is the position at the second moment, is the differential of the target position; Step S202, obtain a target speed according to the target position, the nominal speed, the position at the first moment, and the speed at the first moment, where the target speed is obtained according to the following formula: where v d (k + 1) is the target speed, η(k) is the position at the first moment, and v(k) is the speed at the first moment; Step S203: Obtain the estimated target velocity based on the velocity at the first moment and the estimated velocity at the first moment, and the estimated target velocity is obtained according to the following formula: where r is the fast factor, h0 is the filtering factor, h is the step size, and v d (k) is the target velocity at the first moment, is the estimated target velocity at the first moment, is the estimated target velocity at the second moment, is the differential of the estimated target velocity at the second moment.

3. The model-free adaptive trajectory tracking control method for an underwater robot according to claim 1, characterized in that: Among them, The formula for obtaining the target acceleration based on the velocity at the first moment, the acceleration at the first moment, the estimated target velocity, and the differential term of the estimated target velocity through a second PD controller is: where a d (k + 1) is the target acceleration, is the differential of the estimated target velocity at the second moment, is the estimated target velocity at the second moment, ν(k) is the velocity at the first moment, and a(k) is the acceleration at the first moment.

4. The model-free adaptive trajectory tracking control method for an underwater robot according to claim 1, characterized in that: Among them, The formula for substituting the difference in acceleration at the first moment and the difference in the resultant force and moment at the third moment into the first objective function to obtain the estimated pseudo-Jacobian matrix in Step S4 is: Where, Δa(k) is the difference in acceleration at the first moment, Δτ(k - 1) is the difference in the resultant force and torque at the third moment, η is the first step factor and η ∈ (0, 2), μ is the penalty factor, Φ(k) is the pseudo-Jacobian matrix of the pseudo-dynamic model Δa(k) = Φ(k)Δτ(k - 1), To estimate the pseudo-Jacobian matrix, is the estimated pseudo-Jacobian matrix at the third moment.

5. The model-free adaptive trajectory tracking control method for an underwater robot according to claim 1, characterized in that: Among them, The formula for substituting the estimated pseudo-Jacobian matrix, the resultant force and moment at the third moment, the acceleration at the first moment, and the target acceleration into the second objective function to obtain the resultant force and moment at the first moment in Step S5 is: J(τ(k)) = ‖a d (k + 1) - a(k)‖ 2 + λ‖τ(k) - τ(k - 1)‖ 2 where a d (k + 1) is the target acceleration, a(k) is the acceleration at the first moment, is the estimated pseudo-Jacobian matrix, τ(k - 1) is the resultant force and moment at the third moment, τ(k) is the resultant force and moment at the first moment, ρ is the second step factor, λ is the weight coefficient, and λ >

0.

6. The model-free adaptive trajectory tracking control method for an underwater robot according to claim 1, wherein Further including: When a disturbance occurs in the control system, adjust the estimated pseudo-Jacobian matrix to adapt to the new system state, and the formula for adjusting the estimated pseudo-Jacobian matrix is: where α ∈ (0, 1), b1 and b2 are constants, are the main diagonal elements of the estimated pseudo-Jacobian matrix, is the estimated pseudo-Jacobian matrix of the element in the i-th row and j-th column.

7. The model-free adaptive trajectory tracking control method for an underwater robot according to any one of claims 1-6, characterized in that: Among them, The first moment is the current moment, the second moment is the next moment after the first moment, and the third moment is the moment before the first moment.

8. An underwater robot model-free adaptive trajectory tracking control system, characterized in that, Including: A discretization module for obtaining a reference path and discretizing the reference path to obtain target positions; A target speed generation module, configured to obtain a target speed by means of a first PD controller according to a position at a first moment, a position at a second moment, a speed at the first moment, and the target position, and smooth the target speed by means of a differential tracker according to the target speed at the first moment and an estimated target speed at the first moment to obtain an estimated target speed; A target acceleration generation module, configured to obtain a target acceleration by means of a second PD controller according to the speed at the first moment, the acceleration at the first moment, the estimated target speed, and a differential term of the estimated target speed; A pseudo-Jacobi matrix calculation module, configured to substitute a difference in acceleration at the first moment and a difference in resultant force and torque at a third moment into a first objective function to obtain an estimated pseudo-Jacobi matrix; A resultant force and torque calculation module, configured to substitute the estimated pseudo-Jacobi matrix, the resultant force and torque at the third moment, the acceleration at the first moment, and the target acceleration into a second objective function to obtain a resultant force and torque at the first moment; An update module, wherein an underwater robot operates according to the resultant force and torque at the first moment, and is configured to update the speed at the first moment and the acceleration at the first moment, and repeat the above operations for iteration.

9. An underwater robot, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, the method for model-free adaptive trajectory tracking control of an underwater robot according to any one of claims 1-7 is implemented.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, the method for model-free adaptive trajectory tracking control of an underwater robot according to any one of claims 1-7 is implemented.

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