A fast-converging robust control method for underwater vehicle hovering and depth-fixing

Abstract

The present invention relates to the field of control technology of non-electrical variables, and in particular to a method for rapid convergence and robust control of underwater vehicle hovering and depth setting, comprising the following steps: establishing a nonlinear hovering motion equation of the underwater vehicle and a mathematical model of a buoyancy tank flow control valve; designing an underwater vehicle state observer to extract the motion state signal of the underwater vehicle; considering the interference of the marine environment, filtering the extracted motion state signal of the underwater vehicle; designing a rapid convergence and robust controller for the hovering and depth setting of the underwater vehicle, and analyzing its stability; and using the rapid convergence and robust controller for the hovering and depth setting of the underwater vehicle and the mathematical model of the buoyancy tank flow control valve to control the hovering and depth setting of the underwater vehicle. The method provided by the present invention can ensure the rapid convergence and robustness and control quality of the hovering and depth setting of the underwater vehicle, and meet the requirements of the underwater vehicle for safety and energy consumption in the hovering state.

Description

Technical Field

[0001] The invention relates to the technical field of control of non-electrical variables, and in particular to a fast-convergence robust control method for hovering and depth-fixing of an underwater vehicle. Background Art

[0002] As an underwater platform for detecting seabed resources, underwater vehicles can be suspended at a certain depth above the seabed for a long time, so as to detect seabed mineral resources. The underwater vehicle can be hovered by adjusting its buoyancy by draining and injecting water, which can effectively reduce the energy consumption of the underwater vehicle. Especially under the condition of positive seawater gradient, it can be hovered at a certain depth without draining and injecting water, realizing hovering without energy consumption.

[0003] There are two main control methods for underwater vehicles in hovering control. One is to perform reverse injection and drainage maneuvers or use thrusters to hover according to depth deviation. The control effect of reverse injection and drainage is not ideal due to interference from the marine environment, and long-term and high-frequency drainage and drainage maneuvers are difficult to implement. The other method is to use thruster control, which consumes a lot of energy. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a fast convergence robust control method for an underwater vehicle hovering and depth setting, which can ensure the fast convergence robustness and control quality of the underwater vehicle hovering and depth setting to meet the safety and energy consumption requirements of the underwater vehicle hovering state.

[0005] The present invention is achieved through the following technical solutions:

[0006] A fast convergence robust control method for an underwater vehicle hovering and maintaining depth, comprising the following steps:

[0007] S1: Establish the nonlinear hovering motion equation of underwater vehicle and the mathematical model of buoyancy tank flow control valve;

[0008] S2: Design an underwater vehicle state observer based on the underwater vehicle's nonlinear hovering motion equation and extract the underwater vehicle's motion state signal;

[0009] S3: Considering the interference of the ocean environment, the extracted motion state signal of the underwater vehicle is filtered;

[0010] S4: Based on the sliding mode variable structure control principle, a fast convergence robust controller for hovering and depth-fixing of underwater vehicles is designed according to the motion state signal of the filtered underwater vehicle, and the stability of the fast convergence robust controller for hovering and depth-fixing of underwater vehicles is analyzed;

[0011] S5: Based on the stability of the underwater vehicle hovering depth-fixing fast convergence robust controller, the underwater vehicle hovering depth-fixing fast convergence robust controller and the mathematical model of the buoyancy water tank flow control valve are used to control the underwater vehicle hovering depth-fixing.

[0012] Furthermore, the nonlinear hovering motion equation of the underwater vehicle in step S1 is formula (1):

[0013] (1);

[0014] in: is the vertical velocity of the underwater vehicle in the hull coordinate system, is the absolute value of the vertical velocity in the underwater vehicle hull coordinate system, is the pitch angular velocity of the underwater vehicle in the hull coordinate system, is the absolute value of the longitudinal angular velocity in the underwater vehicle hull coordinate system, is the vertical acceleration of the underwater vehicle in the hull coordinate system, is the longitudinal acceleration of the underwater vehicle in the hull coordinate system, is the longitudinal inclination angle of the underwater vehicle in the fixed coordinate system; is the pitch angular velocity of the underwater vehicle in the fixed coordinate system, is the vertical velocity of the underwater vehicle in the fixed coordinate system; is the actual current depth of the underwater vehicle, is the initial depth of the underwater vehicle, is the initial unbalanced force of the underwater vehicle, is the pitch moment of the underwater vehicle, It is the control force for discharging and filling water in the buoyancy tank. To adjust the water control torque, is the mass of the underwater vehicle, is the density of seawater, is the length of the underwater vehicle, is the acceleration due to gravity, To stabilize the underwater vehicle, is the moment of inertia of the underwater vehicle in the longitudinal direction; is the coupling coefficient of the underwater vehicle's pitch angular velocity and the absolute value of the pitch angular velocity on the depth, is the coupling coefficient of the influence of the absolute value of the vertical velocity and the longitudinal angular velocity of the underwater vehicle on the depth, is the coupling coefficient of the influence of the vertical velocity of the underwater vehicle and the absolute value of the vertical velocity on the depth, is the coupling coefficient of the effect of the depth change of the underwater vehicle on the depth, is the coupling coefficient of the underwater vehicle's pitch angular velocity and the absolute value of the pitch angular velocity on the pitch, is the coupling coefficient of the effect of the vertical velocity of the underwater vehicle and the absolute value of the pitch angular velocity on the pitch, is the coupling coefficient of the influence of the underwater vehicle's vertical velocity and the absolute value of the vertical velocity on the pitch.

[0015] Furthermore, the mathematical model of the buoyancy tank flow control valve in step S1 is formula (2):

[0016] (2);

[0017] in: for The valve opening coefficient at the moment, is the differential of the buoyancy tank dewatering and filling control force, is the drainage water flow rate, is the system response delay time, is the valve opening and closing time.

[0018] Furthermore, the underwater vehicle state observer designed in step S2 is formula (3):

[0019] (3);

[0020] in: is the underwater vehicle depth, is the differential of the underwater vehicle depth, is the vertical speed of the underwater vehicle, is the differential of the vertical velocity of the underwater vehicle, is the system state variable matrix, , is the differential of the system state variable matrix, is the system state matrix, , is the influence coefficient of velocity damping on acceleration, is the influence coefficient of depth change on acceleration, is the system control matrix, , is the system control state quantity, , is the influence coefficient of control force on acceleration, Control force generated by filling the hover row with water.

[0021] Further, in step S2, the underwater vehicle state observer is obtained by the following method:

[0022] S21: Linearize the nonlinear hovering motion equation of the underwater vehicle, and obtain the hovering motion linear equation as formula (4):

[0023] (4);

[0024] in: is the acceleration inertia force coefficient; is the velocity damping coefficient; is the position restoring force coefficient, is the vertical acceleration;

[0025] S22: The filter signal equation obtained from the hovering motion linear equation (4) is equation (5):

[0026] (5);

[0027] S23: , expand equation (5) to obtain the underwater vehicle state observer as equation (3).

[0028] Further, in step S3, the extracted motion state signal of the underwater vehicle is filtered by the following method;

[0029] S31: According to the underwater vehicle state observer formula (3), the Kalman filter is predicted as formula (6):

[0030] (6);

[0031] in: Based on Sub-state quantity mean prediction The state quantity of the second for The mean state quantity of the prediction, Based on The subcovariance matrix predicts The secondary covariance matrix, for The mean covariance matrix of the forecasts, for The output error weight matrix is: Transpose the matrix;

[0032] S32: According to the Kalman filter The mean state quantity of the prediction The modified Kalman filter is obtained by correction as formula (7):

[0033] (7);

[0034] in: for The sub-state gain matrix, for The output state variable matrix, is the output matrix, for The weight matrix of the secondary input;

[0035] S33: Considering the disturbance of the marine environment, the state variables affected by the control force are introduced into the modified Kalman filter , then we get formula (8):

[0036] (8);

[0037] in: .

[0038] Furthermore, the fast-converging robust controller for underwater vehicle hovering and depth-fixing designed in step S4 is formula (9):

[0039] (9);

[0040] in: is the sliding mode switching line parameter.

[0041] Furthermore, the design process of the underwater vehicle hovering depth-fixing fast convergence robust controller in step S4 is as follows:

[0042] S41: According to formula (3), we can get formula (10):

[0043] (10);

[0044] S42: According to the mathematical requirements of the accessibility conditions of sliding mode motion, formula (10) is: There is control force generated by hovering water injection The solution is that when There is a control force generated by hovering and injecting water The solution, , then when Then we have formula (11), when Then we have formula (12):

[0045] According to equation (11) and equation (12), the fast convergence robust controller for underwater vehicle hovering and depth determination is obtained as equation (9):

[0046] (11);

[0047] (12);

[0048] in: is the position state of the point in the reachability condition system space, For the moment.

[0049] Further, the method for analyzing the stability of the underwater vehicle hovering depth-fixing fast convergence robust controller in step S4 is as follows:

[0050] S43: During the actual hovering motion of the underwater vehicle, , , and Substituting into formula (9), we get formula (13):

[0051] (13);

[0052] S44: Due to To determine the value, there is a control force generated by the hovering water injection The solution;

[0053] S45: When the state point performs sliding mode motion, there is and , according to We get formula (14):

[0054] (14);

[0055] S46: Substitute equation (14) into equation (10) to obtain equation (15):

[0056] (15);

[0057] S47: According to formula (15), we can get , , when taking When the state point , the convergence of sliding mode motion is established, and the stability of the underwater vehicle hovering depth-fixed fast convergence robust controller meets the requirements, where: express The initial value of express The initial value of .

[0058] Beneficial effects of the invention:

[0059] The invention provides a fast convergence robust control method for underwater vehicle hovering and depth setting. The fast convergence robust controller for underwater vehicle hovering and depth setting is designed based on filtering the extracted motion state signal of the underwater vehicle in consideration of the interference of the marine environment. It not only has good robustness and can maintain the stability of the system under various uncertainties and external interferences, but also has rapid response capabilities to ensure that the system can reach the expected working state at the fastest speed. In addition, the mathematical model of the designed buoyancy tank flow control valve significantly reduces the number of water discharge and injection, thereby improving the control safety and efficiency of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0061] A fast convergence robust control method for underwater vehicle hovering and depth determination, the flow chart is as follows Figure 1 As shown, the specific steps include:

[0062] S1: Establish the nonlinear hovering motion equation of underwater vehicle and the mathematical model of buoyancy tank flow control valve;

[0063] Specifically, the nonlinear hovering motion equation of the underwater vehicle is as follows:

[0064] (1);

[0065] in: is the vertical velocity of the underwater vehicle in the hull coordinate system, is the absolute value of the vertical velocity in the underwater vehicle hull coordinate system, is the pitch angular velocity of the underwater vehicle in the hull coordinate system, is the absolute value of the longitudinal angular velocity in the underwater vehicle hull coordinate system, is the vertical acceleration of the underwater vehicle in the hull coordinate system, is the longitudinal acceleration of the underwater vehicle in the hull coordinate system, is the longitudinal inclination angle of the underwater vehicle in the fixed coordinate system; is the pitch angular velocity of the underwater vehicle in the fixed coordinate system, is the vertical velocity of the underwater vehicle in the fixed coordinate system; is the actual current depth of the underwater vehicle, is the initial depth of the underwater vehicle, is the initial unbalanced force of the underwater vehicle, is the pitch moment of the underwater vehicle, It is the control force for discharging and filling water in the buoyancy tank. To adjust the water control torque, is the mass of the underwater vehicle, is the density of seawater, is the length of the underwater vehicle, is the acceleration due to gravity, To stabilize the underwater vehicle, is the moment of inertia of the underwater vehicle in the longitudinal direction; is the coupling coefficient of the underwater vehicle's pitch angular velocity and the absolute value of the pitch angular velocity on the depth, is the coupling coefficient of the influence of the absolute value of the vertical velocity and the longitudinal angular velocity of the underwater vehicle on the depth, is the coupling coefficient of the influence of the vertical velocity of the underwater vehicle and the absolute value of the vertical velocity on the depth, is the coupling coefficient of the effect of the depth change of the underwater vehicle on the depth, is the coupling coefficient of the underwater vehicle's pitch angular velocity and the absolute value of the pitch angular velocity on the pitch, is the coupling coefficient of the effect of the vertical velocity of the underwater vehicle and the absolute value of the pitch angular velocity on the pitch, is the coupling coefficient of the influence of the underwater vehicle's vertical velocity and the absolute value of the vertical velocity on the pitch.

[0066] The coupling coefficients in the above formula can be obtained by computational fluid dynamics simulation, which is a prior art.

[0067] The mathematical model of the buoyancy tank flow control valve is as follows:

[0068] (2);

[0069] in: for The valve opening coefficient at the moment, is the differential of the buoyancy tank dewatering and filling control force, is the drainage water flow rate, is the system response delay time, is the valve opening and closing time.

[0070] Introducing valve opening coefficient Describes the degree of valve closure responsible for flow regulation, the valve opening coefficient when the valve is fully closed , valve opening coefficient when fully open By establishing a mathematical model for the flow control valve of the buoyancy tank, the number of water discharge and injection is significantly reduced, thereby improving the control efficiency of the entire system, reducing energy loss, and reducing equipment wear.

[0071] S2: Design an underwater vehicle state observer based on the underwater vehicle's nonlinear hovering motion equation and extract the underwater vehicle's motion state signal;

[0072] Specifically, the designed underwater vehicle state observer is formula (3):

[0073] (3);

[0074] in: is the underwater vehicle depth, is the differential of the underwater vehicle depth, is the vertical speed of the underwater vehicle, is the differential of the vertical velocity of the underwater vehicle, is the system state variable matrix, , is the differential of the system state variable matrix, is the system state matrix, , is the influence coefficient of velocity damping on acceleration, is the influence coefficient of depth change on acceleration, is the system control matrix, , is the system control state quantity, , is the influence coefficient of control force on acceleration, Control force generated by filling the hover row with water.

[0075] The influence coefficients here can be obtained according to the following formula (4): .

[0076] Specifically, the process of obtaining the underwater vehicle state observer is as follows:

[0077] S21: Linearize the nonlinear hovering motion equation of the underwater vehicle, and obtain the hovering motion linear equation as formula (4):

[0078] (4);

[0079] in: is the acceleration inertia force coefficient; is the velocity damping coefficient; is the position restoring force coefficient, is the vertical acceleration;

[0080] Here , , It can be obtained according to formula (1).

[0081] S22: The filter signal equation obtained from the hovering motion linear equation (4) is equation (5):

[0082] (5);

[0083] S23: , expand equation (5) to obtain the underwater vehicle state observer as equation (3).

[0084] S3: Considering the interference of the ocean environment, the extracted motion state signal of the underwater vehicle is filtered;

[0085] Specifically, the following method may be used to filter the extracted motion state signal of the underwater vehicle;

[0086] S31: According to the underwater vehicle state observer formula (3), the Kalman filter is predicted as formula (6):

[0087] (6);

[0088] in: Based on Sub-state quantity mean prediction The state quantity of the second for The mean state quantity of the prediction, Based on The subcovariance matrix predicts The secondary covariance matrix, for The mean covariance matrix of the forecasts, for The output error weight matrix is: Transpose the matrix;

[0089] S32: According to the Kalman filter The mean state quantity of the prediction The modified Kalman filter is obtained by correction as formula (7):

[0090] (7);

[0091] in: for The sub-state gain matrix, for The output state variable matrix, is the output matrix, , , for The weight matrix of the secondary input;

[0092] S33: Considering the disturbance of the marine environment, the state variables affected by the control force are introduced into the modified Kalman filter , then we get formula (8):

[0093] (8);

[0094] in: .

[0095] Since the interference of the ocean environment is taken into account when filtering the extracted motion state signal of the underwater vehicle, the state variable affected by the control force is introduced into the modified Kalman filter , , so that the pair obtained later according to formula (8) The mean state quantity of the prediction By eliminating the influence of marine environmental interference, the prediction results are more accurate and stable. Based on this, a fast-convergence robust controller for hovering and depth-fixing of underwater vehicles is designed to control the hovering and depth-fixing of underwater vehicles. It not only has good robustness but also has rapid response capability. It can maintain the stability of the system and the accuracy of control under various uncertainties and external interferences, thereby improving the control safety of the entire system.

[0096] S4: Based on the sliding mode variable structure control principle, a fast convergence robust controller for hovering and depth-fixing of underwater vehicles is designed according to the motion state signal of the filtered underwater vehicle, and the stability of the fast convergence robust controller for hovering and depth-fixing of underwater vehicles is analyzed;

[0097] Furthermore, the fast-converging robust controller for underwater vehicle hovering and depth-fixing designed in step S4 is formula (9):

[0098] (9);

[0099] in: is the sliding mode switching line parameter, and the actual value can be set based on experience.

[0100] Specifically, the design process of the underwater vehicle hovering depth-fixing fast convergence robust controller in step S4 is as follows:

[0101] S41: According to formula (3), we can get formula (10):

[0102] (10);

[0103] S42: According to the mathematical requirements of the accessibility conditions of sliding mode motion, formula (10) is: There is control force generated by hovering water injection The solution is that when There is a control force generated by hovering and injecting water The solution, , then when Then we have formula (11), when Then we have formula (12):

[0104] According to equation (11) and equation (12), the fast convergence robust controller for underwater vehicle hovering and depth determination is obtained as equation (9):

[0105] (11);

[0106] (12);

[0107] in: is the position state of the point in the reachability condition system space, For the moment.

[0108] Specifically, the method for analyzing the stability of the underwater vehicle hovering depth-fixing fast convergence robust controller is as follows:

[0109] S43: During the actual hovering motion of the underwater vehicle, , , and Substituting into formula (9), we get formula (13):

[0110] (13);

[0111] S44: Due to To determine the value, there is a control force generated by the hovering water injection The solution;

[0112] S45: When the state point performs sliding mode motion, there is and , according to We get formula (14):

[0113] (14);

[0114] S46: Substitute equation (14) into equation (10) to obtain equation (15):

[0115] (15);

[0116] S47: According to formula (15), we can get , , when taking When the state point , the convergence of sliding mode motion is established, and the stability of the underwater vehicle hovering depth-fixed fast convergence robust controller meets the requirements, where: express The initial value of express The initial value of .

[0117] On the basis of proving that the obtained underwater vehicle hovering depth-fixing fast convergence robust controller is globally asymptotically stable, it is used to perform hovering depth-fixing control on the underwater vehicle, which can not only ensure the control accuracy and improve the robustness, but also reduce the number of water discharge and injection times during the hovering process of the underwater vehicle.

[0118] S5: Based on the stability of the underwater vehicle hovering depth-fixing fast convergence robust controller, the underwater vehicle hovering depth-fixing fast convergence robust controller and the mathematical model of the buoyancy water tank flow control valve are used to control the underwater vehicle hovering depth-fixing.

[0119] The invention adopts a fast convergence robust control method for hovering and depth-fixing of underwater vehicles to control the hovering and depth-fixing of underwater vehicles. Considering the interference of the ocean environment, the state variables affected by the control force are introduced into the modified Kalman filter. , so that the later obtained The mean state quantity of the prediction The influence of marine environmental interference is eliminated, and the extracted motion state signal of the underwater vehicle is filtered, so that the underwater vehicle hovering and depth-fixing fast convergence robust controller designed on this basis not only has good robustness and can maintain the stability of the system under various uncertainties and external interferences, but also has rapid response capabilities to ensure that the system can reach the expected working state at the fastest speed. In addition, the mathematical model of the designed buoyancy tank flow control valve significantly reduces the number of water discharge and injection, thereby improving the control safety and efficiency of the entire system.

[0120] In summary, the present invention provides a fast convergence robust control method for an underwater vehicle hovering and depth setting, which can ensure the fast convergence robustness and control quality of the underwater vehicle hovering and depth setting, and meet the requirements of safety and energy consumption of the underwater vehicle hovering state.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fast convergence robust control method for underwater vehicle hovering and depth determination, characterized by: The steps include: S1: Establish the nonlinear hovering motion equation of underwater vehicle and the mathematical model of buoyancy tank flow control valve; The nonlinear hovering motion equation of the underwater vehicle is as follows: （1）； in: is the vertical velocity of the underwater vehicle in the hull coordinate system, is the absolute value of the vertical velocity in the underwater vehicle hull coordinate system, is the pitch angular velocity of the underwater vehicle in the hull coordinate system, is the absolute value of the longitudinal angular velocity in the underwater vehicle hull coordinate system, is the vertical acceleration of the underwater vehicle in the hull coordinate system, is the longitudinal acceleration of the underwater vehicle in the hull coordinate system, is the longitudinal inclination angle of the underwater vehicle in the fixed coordinate system; is the pitch angular velocity of the underwater vehicle in the fixed coordinate system, is the vertical velocity of the underwater vehicle in the fixed coordinate system; is the actual current depth of the underwater vehicle, is the initial depth of the underwater vehicle, is the initial unbalanced force of the underwater vehicle, is the pitch moment of the underwater vehicle, It is the control force for discharging and filling water in the buoyancy tank. To adjust the water control torque, is the mass of the underwater vehicle, is the density of seawater, is the length of the underwater vehicle, is the acceleration due to gravity, To stabilize the underwater vehicle, is the moment of inertia of the underwater vehicle in the longitudinal direction; is the coupling coefficient of the underwater vehicle's pitch angular velocity and the absolute value of the pitch angular velocity on the depth, is the coupling coefficient of the influence of the absolute value of the vertical velocity and the longitudinal angular velocity of the underwater vehicle on the depth, is the coupling coefficient of the influence of the vertical velocity of the underwater vehicle and the absolute value of the vertical velocity on the depth, is the coupling coefficient of the effect of the depth change of the underwater vehicle on the depth, is the coupling coefficient of the underwater vehicle's pitch angular velocity and the absolute value of the pitch angular velocity on the pitch, is the coupling coefficient of the effect of the vertical velocity of the underwater vehicle and the absolute value of the pitch angular velocity on the pitch, is the coupling coefficient of the effect of the underwater vehicle vertical velocity and the absolute value of the vertical velocity on the pitch; The mathematical model of the buoyancy tank flow control valve is as follows: （2）； in: for The valve opening coefficient at the moment, is the differential of the buoyancy tank dewatering and filling control force, is the drainage water flow rate, is the system response delay time, is the valve opening and closing time; S2: Design an underwater vehicle state observer based on the underwater vehicle's nonlinear hovering motion equation and extract the underwater vehicle's motion state signal; S3: Considering the interference of the ocean environment, the extracted motion state signal of the underwater vehicle is filtered; S4: Based on the sliding mode variable structure control principle, a fast convergence robust controller for hovering and depth-fixing of underwater vehicles is designed according to the motion state signal of the filtered underwater vehicle, and the stability of the fast convergence robust controller for hovering and depth-fixing of underwater vehicles is analyzed; S5: Based on the stability of the underwater vehicle hovering depth-fixing fast convergence robust controller, the underwater vehicle hovering depth-fixing fast convergence robust controller and the mathematical model of the buoyancy water tank flow control valve are used to control the underwater vehicle hovering depth-fixing.

2. The fast convergence robust control method for hovering and depth-fixing of an underwater vehicle according to claim 1, characterized in that: The underwater vehicle state observer designed in step S2 is formula (3): （3）； in: is the underwater vehicle depth, is the differential of the underwater vehicle depth, is the vertical speed of the underwater vehicle, is the differential of the vertical velocity of the underwater vehicle, is the system state variable matrix, , is the differential of the system state variable matrix, is the system state matrix, , is the influence coefficient of velocity damping on acceleration, is the influence coefficient of depth change on acceleration, is the system control matrix, , is the system control state quantity, , is the influence coefficient of control force on acceleration, Control force generated by filling the hover row with water.

3. The fast convergence robust control method for hovering and depth-fixing of an underwater vehicle according to claim 2, characterized in that: In step S2, the underwater vehicle state observer is obtained by the following method: S21: Linearize the nonlinear hovering motion equation of the underwater vehicle, and obtain the hovering motion linear equation as formula (4): （4）； in: is the acceleration inertia force coefficient; is the velocity damping coefficient; is the position restoring force coefficient, is the vertical acceleration; S22: The filter signal equation obtained from the hovering motion linear equation (4) is equation (5): （5）； S23: , expand equation (5) to obtain the underwater vehicle state observer as equation (3).

4. The fast convergence robust control method for hovering and depth-fixing of an underwater vehicle according to claim 2, characterized in that: In step S3, the extracted motion state signal of the underwater vehicle is filtered using the following method; S31: According to the underwater vehicle state observer formula (3), the Kalman filter is predicted as formula (6): （6）； in: Based on Sub-state quantity mean prediction The state quantity of the second for The mean state quantity of the prediction, Based on The subcovariance matrix predicts The secondary covariance matrix, for The mean covariance matrix of the forecasts, for The output error weight matrix is: Transpose the matrix; S32: According to the Kalman filter The mean state quantity of the prediction The modified Kalman filter is obtained by correction as formula (7): （7）； in: for The sub-state gain matrix, for The output state variable matrix, is the output matrix, for The weight matrix of the secondary input; S33: Considering the disturbance of the marine environment, the state variables affected by the control force are introduced into the modified Kalman filter , then we get formula (8): （8）； in: .

5. The fast convergence robust control method for hovering and depth-fixing of an underwater vehicle according to claim 4, characterized in that: The fast-converging robust controller for underwater vehicle hovering and depth-fixing designed in step S4 is formula (9): （9）； in: is the sliding mode switching line parameter.

6. The fast convergence robust control method for hovering and depth-fixing of an underwater vehicle according to claim 5, characterized in that: The design process of the underwater vehicle hovering depth-fixing fast convergence robust controller in step S4 is as follows: S41: According to formula (3), we can get formula (10): （10）； S42: According to the mathematical requirements of the accessibility conditions of sliding mode motion, formula (10) is: There is control force generated by hovering water injection The solution is that when There is a control force generated by hovering and injecting water The solution, , then when Then we have formula (11), when Then we have formula (12): According to equation (11) and equation (12), the fast convergence robust controller for underwater vehicle hovering and depth determination is obtained as equation (9): （11）； （12）； in: is the position state of the point in the reachability condition system space, For the moment.

7. The fast convergence robust control method for hovering and depth-fixing of an underwater vehicle according to claim 6, characterized in that: The method for analyzing the stability of the underwater vehicle hovering depth-fixing fast convergence robust controller in step S4 is as follows: S43: During the actual hovering motion of the underwater vehicle, , , and Substituting into formula (9), we get formula (13): （13）； S44: Due to To determine the value, there is a control force generated by the hovering water injection The solution; S45: When the state point performs sliding mode motion, there is and , according to We get formula (14): (14)； S46: Substitute equation (14) into equation (10) to obtain equation (15): （15）； S47: According to formula (15), we can get , , when taking When the state point , the convergence of sliding mode motion is established, and the stability of the underwater vehicle hovering depth-fixed fast convergence robust controller meets the requirements, where: express The initial value of express The initial value of .

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