CN109976384B - Autonomous underwater robot and path following control method and device - Google Patents

Abstract

Embodiments of the present invention provide an autonomous underwater robot and a path following control method and device, which relate to the technical field of robotics. Obtain the built autonomous underwater robot motion system; generate a nonlinear dynamic system of the autonomous underwater robot motion system according to the principles of physics; receive the real-time position of the autonomous underwater robot acquired by the positioning module, and The dynamic model is used to rewrite the real-time position; based on the interference term of the autonomous underwater robot, the real-time position and the preset input-state stability theory, a nonlinear robust backstepping controller is generated, and the autonomous underwater robot is The motion system is controlled so that the autonomous underwater robot can independently complete the precise path following operation and achieve stable work.

Description

An autonomous underwater robot and a path following control method and device

technical field

The invention relates to the technical field of robots, in particular to an autonomous underwater robot and a path following control method and device.

Background technique

Autonomous underwater robots can replace or assist humans to complete various difficult or dangerous tasks underwater without real-time human control, which is very important to its research and development. Underwater robots work in an unknown and challenging underwater environment. The complex underwater environment such as wind, waves, currents, and deep water pressure seriously interferes with the motion of underwater robots. The traditional path following control of land robots cannot be simply extended to water. In the path following control of the robot, the path control strategy in the complex underwater environment must be sought.

SUMMARY OF THE INVENTION

In view of this, the purpose of the embodiments of the present invention is to provide an autonomous underwater robot and a path following control method and device, so as to improve the problem that the underwater environment seriously interferes with the movement of the underwater robot in the prior art.

A preferred embodiment of the present invention provides a path following control method for an autonomous underwater robot, comprising the following steps:

Acquiring the built autonomous underwater robot motion system; wherein, the autonomous underwater robot motion system includes a pusher, a load, a positioning module and a robot base;

According to the principle of physics, a nonlinear dynamic system of the autonomous underwater robot motion system is generated; wherein, the nonlinear dynamic system includes a dynamic model of the autonomous underwater robot;

receiving the real-time position of the autonomous underwater robot obtained by the positioning module, and rewriting the real-time position according to the dynamic model;

Generate a nonlinear robust backstepping controller based on the disturbance term, real-time position and preset input-state stability theory of the autonomous underwater vehicle;

The motion system of the autonomous underwater robot is controlled based on the nonlinear robust backstepping controller, so that the autonomous underwater robot can autonomously and independently complete the precise path following operation and achieve stable work.

Preferably, the dynamic model of the autonomous underwater robot is:

Among them, m is the mass of the autonomous underwater robot; r is the three-dimensional position coordinate of the autonomous underwater robot during operation, and r ₌ [r _x , ry , r _z ] ^T ; F _m is the propeller to the autonomous underwater robot The driving force of the robot, and F _m = [F _mx , F _my , F _mz ] ^T ; F _d is the liquid viscous resistance of the autonomous underwater robot when it moves in water, and F _d =[F _dx , F _dy , F _dz ] ^T .

Preferably, the steps of receiving the real-time position of the autonomous underwater robot obtained by the positioning module, and rewriting the real-time position according to the dynamic model are:

Simplify the appearance of the autonomous underwater robot into a spherical shape, which is obtained by Stokes formula,

F _d =6πηRυ (2)

Among them, η is the liquid viscosity coefficient of the water environment where the autonomous underwater robot is located, R is the radius of the autonomous underwater robot, υ = [υ _x , υ _y , υ _z ] ^T is the autonomous underwater robot when the autonomous underwater robot is operating underwater The speed of movement relative to the water environment;

趋于0；Define r _d as the preset path coordinates during the operation of the autonomous underwater robot, r _o as the coordinates of the real-time position obtained by the positioning module during the operation of the autonomous underwater robot, and follow the path of the autonomous underwater robot during the underwater operation The control objective can be converted so that the position error e=r _d -r _o and

tends to 0;

公式(1)变为：Rewrite formula (1) into a state space expression to further define

Formula (1) becomes:

以及

in,

as well as

Preferably, the interference term of the autonomous underwater robot includes wind, wave, current or deep water pressure encountered by the autonomous underwater robot during underwater operation, and the interference term is attributed to the coefficient Δ=[Δ _x , Δ _y , Δ _z ] ^T , and regard Δ as an unknown bounded coefficient vector, then formula (1) becomes:

Converted to a state space expression, Equation (2) becomes:

Preferably, based on the disturbance term, real-time position and input-state stability theory of the autonomous underwater vehicle, the step of generating a nonlinear robust backstepping controller includes:

Based on the input-state stability theory, a nonlinear robust backstepping controller is generated:

k1，k2以及δ为非负控制增益。in,

k1, k2 and δ are non-negative control gains.

For the nonlinear dynamic system, the following Lyapunov function is established:

Taking the derivation of formula (7), we get:

by the inequality

where δ>0;

Substituting inequality (9) into formula (8), we get:

Substituting the nonlinear robust backstepping controller (6) into inequality (10), we get:

Taking a positive number K=min{k ₁ , k ₂ }, inequality (10) can be simplified as:

Multiplying both sides of inequality (12) by e ^2Kt and integrating it in [0, t], we get:

Taking the square root operation on both sides of inequality (13), and substituting Lyapunov function (7) into inequality (13), we get:

Inequality (14) reflects the input-state stability of the entire path following control system, and it shows the upper bound of the position tracking error and velocity tracking error under the action of bounded unknown disturbances, so that the autonomous underwater robot is autonomous and independent Complete precise path following jobs and achieve stable work.

An embodiment of the present invention also provides a path following control device for an autonomous underwater robot, including:

a motion system acquisition unit, used for acquiring a built autonomous underwater robot motion system; wherein, the autonomous underwater robot motion system includes a pusher, a load, a positioning module and a robot base;

a nonlinear system generation unit, configured to generate a nonlinear dynamic system of the autonomous underwater robot motion system according to the principle of physics; wherein, the nonlinear dynamic system includes a dynamic model of the autonomous underwater robot;

a rewriting unit, configured to receive the real-time position of the autonomous underwater robot acquired by the positioning module, and rewrite the real-time position according to the dynamic model;

A controller generation unit for generating a nonlinear robust backstepping controller based on the disturbance term, real-time position and preset input-state stability theory of the autonomous underwater vehicle;

The control unit is used for controlling the motion system of the autonomous underwater robot based on the nonlinear robust backstepping controller, so that the autonomous underwater robot can independently complete the precise path following operation and realize stable work.

An embodiment of the present invention further provides an autonomous underwater robot, including a processor, a memory, and executable code stored in the memory, where the executable code can be executed by the processor to implement the above-mentioned path following control method .

In the above-mentioned embodiment, by constructing the autonomous underwater robot motion system, and establishing the non-linear dynamic system of the autonomous underwater robot motion system, and based on the interference term of the autonomous underwater robot, the real-time position and the preset input-state stability According to the theory, a nonlinear robust backstepping controller is generated to control the motion system of the autonomous underwater robot, so that the autonomous underwater robot can independently complete the accurate path following operation and achieve stable work.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic structural diagram of an autonomous underwater robot motion system provided by a first embodiment of the present invention;

2 is a schematic flowchart of a path following control method for an autonomous underwater robot provided by the first embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a path following control device for an autonomous underwater robot according to a second embodiment of the present invention.

Icons: 100-autonomous underwater robot motion system; 10-propeller; 20-load; 30-positioning module; 40-robot base; 210-motion system acquisition unit; 220-nonlinear system generation unit; 230-rewrite unit; 240 - controller generation unit; 250 - control unit.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and generated in a variety of different configurations. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

Referring to FIG. 1, the first embodiment of the present invention provides a path following control method for an autonomous underwater robot, including the following steps:

S101 , acquiring a built autonomous underwater robot motion system 100 . Wherein, as shown in FIG. 2 , the autonomous underwater robot motion system 100 includes a pusher 10 , a load 20 , a positioning module 30 and a robot base 40 .

S102, according to the principles of physics, generate a nonlinear dynamic system of the autonomous underwater robot motion system 100; wherein, the nonlinear dynamic system includes a dynamic model of the autonomous underwater robot.

Specifically, in this embodiment, the dynamic model of the autonomous underwater robot is:

Among them, m is the mass of the autonomous underwater robot; r is the three-dimensional position coordinate of the autonomous underwater robot during operation, and r ₌ [r _x , ry , r _z ] ^T ; F _m is the pusher 10 to the autonomous water The driving force of the lower robot, and F _m = [F _mx , F _my , F _mz ] ^T ; F _d is the liquid viscous resistance of the autonomous underwater robot when it moves in water, and F _d =[F _dx , F _dy , F _dz ] ^T .

S103: Receive the real-time position of the autonomous underwater robot obtained by the positioning module 30, and rewrite the real-time position according to the dynamic model.

Specifically, the appearance of the autonomous underwater robot is simplified into a spherical shape, which is obtained by Stokes formula,

F _d =6πηRυ (2)

Among them, η is the liquid viscosity coefficient of the water environment where the autonomous underwater robot is located, R is the radius of the autonomous underwater robot, υ = [υ _x , υ _y , υ _z ] ^T is the autonomous underwater robot when the autonomous underwater robot is operating underwater The speed of movement relative to the water environment;

趋于0；Definition r _d is the preset path coordinate during the operation of the autonomous underwater robot, r _o is the coordinate of the real-time position obtained by the positioning module 30 during the operation of the autonomous underwater robot, and the path of the autonomous underwater robot during the underwater operation is defined. The following control objective can be converted such that the position error e=r _d -r _o and

tends to 0;

公式(1)变为：Rewrite formula (1) into a state space expression to further define

Formula (1) becomes:

以及

in,

as well as

S104, a nonlinear robust backstepping controller is generated based on the disturbance term, real-time position and preset input-state stability theory of the autonomous underwater robot.

Wherein, the interference term of the autonomous underwater robot includes wind, wave, current or deep water pressure encountered by the autonomous underwater robot during underwater operation, and the interference term is attributed to the coefficient Δ=[Δ _x , Δ _y , Δ _z ] ^T , and regard Δ as an unknown bounded coefficient vector, then formula (1) becomes:

Converted to a state space expression, Equation (2) becomes:

Based on the disturbance term, real-time position and input-state stability theory of autonomous underwater vehicles, the steps to generate a nonlinear robust backstepping controller include:

Based on the input-state stability theory, a nonlinear robust backstepping controller is generated:

k1，k2以及δ为非负控制增益。in,

k1, k2 and δ are non-negative control gains.

For the nonlinear dynamic system, the following Lyapunov function is established:

Taking the derivation of formula (7), we get:

by the inequality

where δ>0;

Substituting inequality (9) into formula (8), we get:

Substituting the nonlinear robust backstepping controller (6) into inequality (10), we get:

Taking a positive number K=min{k ₁ , k ₂ }, inequality (10) can be simplified as:

Multiplying both sides of inequality (12) by e ^2Kt and integrating it in [0, t], we get:

Taking the square root operation on both sides of inequality (13), and substituting Lyapunov function (7) into inequality (13), we get:

S105, the autonomous underwater robot motion system 100 is controlled based on the nonlinear robust backstepping controller, so that the autonomous underwater robot can autonomously and independently complete the precise path following operation and achieve stable operation.

As shown in inequality (14) above, this inequality reflects the input-state stability of the entire path following control system, and it shows the upper bounds of position tracking error and velocity tracking error under the action of bounded unknown disturbances. Further, if the disturbance disappears, both the position and velocity tracking errors can converge to zero. Selecting appropriate control parameters k1, k2 and δ, the designed path following controller (see formula (6)) will make the autonomous underwater robot path following system run stably.

To sum up, by constructing the autonomous underwater robot motion system 100, and establishing a non-linear dynamic system of the autonomous underwater robot motion system 100, based on the interference term, real-time position and preset input-state of the autonomous underwater robot Based on the stability theory, a nonlinear robust backstepping controller is generated to control the motion system 100 of the autonomous underwater robot, so that the autonomous underwater robot can autonomously and independently complete the precise path following operation and achieve stable work.

Please refer to FIG. 3 , the second embodiment of the present invention also provides a path following control device for an autonomous underwater robot, including:

The motion system acquisition unit 210 is used to acquire the constructed autonomous underwater robot motion system 100 , wherein the autonomous underwater robot motion system 100 includes a pusher 10 , a load 20 , a positioning module 30 and a robot base 40 .

The nonlinear system generating unit 220 is configured to generate a nonlinear dynamic system of the autonomous underwater robot motion system 100 according to the principle of physics; wherein, the nonlinear dynamic system includes a dynamic model of the autonomous underwater robot.

Wherein, in this embodiment, the dynamics model of the autonomous underwater robot is:

Among them, m is the mass of the autonomous underwater robot; r is the three-dimensional position coordinate of the autonomous underwater robot during operation, and r ₌ [r _x , ry , r _z ] ^T ; F _m is the propeller to the autonomous underwater robot The driving force of the robot, and F _m = [F _mx , F _my , F _mz ] ^T ; F _d is the liquid viscous resistance of the autonomous underwater robot when it moves in water, and F _d =[F _dx , F _dy , F _dz ] ^T .

The rewriting unit 230 is configured to receive the real-time position of the autonomous underwater robot acquired by the positioning module 30, and rewrite the real-time position according to the dynamic model.

Wherein, in the rewriting unit 230 in this implementation, the steps for receiving the real-time position of the autonomous underwater robot obtained by the positioning module, and rewriting the real-time position according to the dynamic model are:

Simplify the appearance of the autonomous underwater robot into a spherical shape, which is obtained by Stokes formula,

F _d =6nηRυ (22)

Among them, η is the liquid viscosity coefficient of the water environment where the autonomous underwater robot is located, R is the radius of the autonomous underwater robot, υ = [υ _x , υ _y , υ _z ] ^T is the autonomous underwater robot when the autonomous underwater robot is operating underwater The speed of movement relative to the water environment;

趋于0；Define r _d as the preset path coordinates during the operation of the autonomous underwater robot, r _o as the coordinates of the real-time position obtained by the positioning module during the operation of the autonomous underwater robot, and follow the path of the autonomous underwater robot during the underwater operation The control objective can be converted so that the position error e=r _d -r _o and

tends to 0;

公式(21)变为：Rewrite formula (21) into a state space expression to further define

Equation (21) becomes:

以及

in,

as well as

The controller generating unit 240 is configured to generate a nonlinear robust backstepping controller based on the disturbance term, real-time position and preset input-state stability theory of the autonomous underwater vehicle.

Wherein, in the controller generation unit 240 of this embodiment, the interference item of the autonomous underwater robot includes wind, wave, current or deep water pressure encountered by the autonomous underwater robot during underwater operation, and the interference item is attributed to to the coefficient Δ=[Δ _x , Δ _y , Δ _z ] ^T , and regard Δ as an unknown bounded coefficient vector, then formula (21) becomes:

Converted to a state space expression, Equation (22) becomes:

Preferably, in the controller generating unit 240, the steps for generating a nonlinear robust backstepping controller based on the disturbance term, real-time position and input-state stability theory of the autonomous underwater vehicle include:

Based on the input-state stability theory, a nonlinear robust backstepping controller is generated:

k1，k2以及δ为非负控制增益。in,

k1, k2 and δ are non-negative control gains.

For the nonlinear dynamic system, a building unit is also included, and the building unit includes establishing the following Lyapunov function:

Derivation of formula (27) yields:

by the inequality

where δ>0;

Substituting inequality (29) into equation (28), we get:

Substituting the nonlinear robust backstepping controller (26) into inequality (210), we get:

Taking a positive number K=min{k ₁ , k ₂ }, inequality (210) can be simplified as:

Multiplying both sides of inequality (212) by e ^2Kt and integrating it in [0, t], we get:

Taking the square root operation on both sides of inequality (213), and substituting Lyapunov function (7) into inequality (213), we get:

The control unit 250 is configured to control the autonomous underwater robot motion system 100 based on the nonlinear robust backstepping controller, so that the autonomous underwater robot can autonomously and independently complete the precise path following operation and achieve stable operation. As shown in the above inequality (214), this inequality reflects the input-state stability of the entire path following control system, and it indicates the upper bound of the position tracking error and velocity tracking error under the action of bounded unknown disturbances. Further, if the disturbance disappears, both the position and velocity tracking errors can converge to zero. Selecting appropriate control parameters k1, k2 and δ, the designed path following controller (see formula (26)) will make the autonomous underwater robot path following system run stably.

A third embodiment of the present invention also provides an autonomous underwater robot, including a processor, a memory, and executable code stored in the memory, the executable code being executable by the processor to implement the above-mentioned path following Control Method.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (3)

1. An autonomous underwater robot path following control method is characterized by comprising the following steps:

acquiring a built autonomous underwater robot motion system; the autonomous underwater robot motion system comprises a pusher, a load, a positioning module and a robot base body;

generating a nonlinear dynamic system of the autonomous underwater robot motion system according to a physics principle; wherein the nonlinear dynamic system comprises a dynamical model of the autonomous underwater robot;

receiving the real-time position of the autonomous underwater robot acquired by the positioning module, and rewriting the real-time position according to the dynamic model;

generating a nonlinear robust backstepping controller based on an interference item, a real-time position and a preset input-state stability theory of the autonomous underwater robot;

controlling the autonomous underwater robot motion system based on the nonlinear robust backstepping controller, so that the autonomous underwater robot autonomously and independently completes accurate path following operation and realizes stable work;

the dynamic model of the autonomous underwater robot is as follows:

wherein m is the mass of the autonomous underwater robot; r is a three-dimensional position coordinate at the time of autonomous underwater robot operation, and r ═ r_x,r_y,r_z]^T；F_mIs the driving force of the propeller to the autonomous underwater robot, and F_m＝[F_mx,F_my,F_mz]^T；F_dIs the liquid viscous resistance that the autonomous underwater robot is subjected to when moving in water, and F_d＝[F_dx,F_dy,F_dz]^T；

The steps of receiving the real-time position of the autonomous underwater robot acquired by the positioning module and rewriting the real-time position according to the dynamic model are as follows:

simplifying the appearance of the autonomous underwater robot into a spherical shape, which is obtained by a Stokes formula,

F_d＝6πηRυ (2)

wherein eta is the liquid viscosity coefficient of the water environment where the autonomous underwater robot is located, R is the radius of the autonomous underwater robot, and upsilon is [ v ═ v [ [ v ]_x,v_y,v_z]^TThe motion speed of the autonomous underwater robot relative to the water environment during underwater operation is obtained;

definition of r_dIs a preset path coordinate r of the autonomous underwater robot during operation_oThe coordinates of the real-time position obtained by the positioning module when the autonomous underwater robot works can be converted into the position error e-r when the path following control target of the autonomous underwater robot works underwater_d-r_oAnd

tends to 0;

rewriting the formula (1) into a state space expression, and further defining

The formula (1) becomes:

wherein,

and

the interference items of the autonomous underwater robot comprise wind, wave, stream or deep water pressure encountered during underwater operation of the autonomous underwater robot, and the interference items are reduced to a coefficient delta ═ delta_x，Δ_y，Δ_z]^TAnd viewing Δ as an unknown bounded coefficient vector, equation (1) becomes:

converted to a state space expression, equation (2) becomes:

the method for generating the nonlinear robust backstepping controller based on the interference item, the real-time position and the input-state stability theory of the autonomous underwater robot comprises the following steps:

generating a nonlinear robust backstepping controller based on an input-state stability theory:

wherein,

k₁，k₂and δ is a non-negative control gain;

for the nonlinear dynamical system, the following Lyapunov function is established:

derivation of equation (7) yields:

by inequality

Wherein δ is > 0;

substituting the inequality (9) into the formula (8) can obtain:

substituting the nonlinear robust backstepping controller (6) into an inequality (10) to obtain:

taking a positive number K ═ min { K ═ K₁，k₂The inequality (10) can be simplified as:

e is multiplied by two sides of inequality (12)^2KtAnd for it to be [0, t]Integration is performed to obtain:

and (3) performing square-opening operation on two sides of the inequality (13) respectively, and substituting the Lyapunov function (7) into the inequality (13) to obtain:

the inequality (14) reflects the input-state stability of the entire path following control system and indicates the upper bound of the position tracking error and the speed tracking error under the action of bounded unknown disturbance, so that the autonomous underwater robot autonomously and independently completes accurate path following operation and realizes stable work.

2. An autonomous underwater robot path following control device, comprising:

the motion system acquisition unit is used for acquiring the built autonomous underwater robot motion system; the autonomous underwater robot motion system comprises a pusher, a load, a positioning module and a robot base body;

the nonlinear system generating unit is used for generating a nonlinear dynamic system of the autonomous underwater robot motion system according to a physics principle; wherein the nonlinear dynamic system comprises a dynamical model of the autonomous underwater robot;

the rewriting unit is used for receiving the real-time position of the autonomous underwater robot acquired by the positioning module and rewriting the real-time position according to the dynamic model;

the controller generation unit is used for generating a nonlinear robust backstepping controller based on an interference item, a real-time position and a preset input-state stability theory of the autonomous underwater robot;

the control unit is used for controlling the autonomous underwater robot motion system based on the nonlinear robust backstepping controller, so that the autonomous underwater robot autonomously and independently completes accurate path following operation and realizes stable operation;

the dynamic model of the autonomous underwater robot is as follows:

wherein m is the mass of the autonomous underwater robot; r is a three-dimensional position coordinate at the time of autonomous underwater robot operation, and r ═ r_x，r_y，r_z]^T；F_mIs the driving force of the propeller to the autonomous underwater robot, and F_m＝[F_mx，F_my，F_mz]^T；F_dIs the liquid viscous resistance that the autonomous underwater robot is subjected to when moving in water, and F_d＝[F_dx，F_dv，F_dz]^T；

The steps of receiving the real-time position of the autonomous underwater robot acquired by the positioning module and rewriting the real-time position according to the dynamic model are as follows:

simplifying the appearance of the autonomous underwater robot into a spherical shape, which is obtained by a Stokes formula,

F_d＝6πηRv (2)

wherein eta is the liquid viscosity coefficient of the water environment where the autonomous underwater robot is located, R is the radius of the autonomous underwater robot, and upsilon is [ v ═ v [ [ v ]_x，v_y，v_z]^TThe motion speed of the autonomous underwater robot relative to the water environment during underwater operation is obtained;

definition of r_dIs a preset path coordinate r of the autonomous underwater robot during operation_oThe coordinates of the real-time position obtained by the positioning module when the autonomous underwater robot works can be converted into the position error e-r when the path following control target of the autonomous underwater robot works underwater_d-r_oAnd

tends to 0;

rewriting the formula (1) into a state space expression, and further defining

The formula (1) becomes:

wherein,

and

the interference items of the autonomous underwater robot comprise wind, wave, stream or deep water pressure encountered during underwater operation of the autonomous underwater robot, and the interference items are reduced to a coefficient delta ═ delta_x，Δ_y，Δ_z]^TAnd viewing Δ as an unknown bounded coefficient vector, equation (1) becomes:

converted to a state space expression, equation (2) becomes:

the method for generating the nonlinear robust backstepping controller based on the interference item, the real-time position and the input-state stability theory of the autonomous underwater robot comprises the following steps:

generating a nonlinear robust backstepping controller based on an input-state stability theory:

wherein,

k₁，k₂and δ is a non-negative control gain;

for the nonlinear dynamical system, the following Lyapunov function is established:

derivation of equation (7) yields:

by inequality

Wherein δ is > 0;

substituting the inequality (9) into the formula (8) can obtain:

substituting the nonlinear robust backstepping controller (6) into an inequality (10) to obtain:

taking a positive number K ═ min { K ═ K₁，k₂The inequality (10) can be simplified as:

e is multiplied by two sides of inequality (12)^2KtAnd for it to be [0, t]Integration is performed to obtain:

and (3) performing square-opening operation on two sides of the inequality (13) respectively, and substituting the Lyapunov function (7) into the inequality (13) to obtain:

the inequality (14) reflects the input-state stability of the entire path following control system and indicates the upper bound of the position tracking error and the speed tracking error under the action of bounded unknown disturbance, so that the autonomous underwater robot autonomously and independently completes accurate path following operation and realizes stable work.

3. An autonomous underwater robot comprising a processor, a memory, and executable code stored in the memory, the executable code executable by the processor to implement the path-following control method of claim 1.

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