Non-turning direct navigation thrust control method for AUV (Autonomous Underwater Vehicle) adsorption crawling

Abstract

The invention discloses a non-rotating-circle direct navigation thrust control method for AUV adsorption crawling. The method comprises the steps that the rotating speed and the corresponding power of a top turbine during AUV direct navigation and the distance between the gravity center of the AUV and the wall face are collected; calculating the frictional resistance of each top turbine based on the rotating speed and the power; calculating water resistance in the horizontal direction and horizontal frictional resistance caused by vertical force based on the near wall surface distance; carrying out mechanical analysis by combining the resistance, and establishing a stress balance equation and a moment balance equation of the direct navigation of the AUV; according to the equation set, reversely deducing the target thrust required by each tail propeller; finally, the rotating speed of each propeller is determined according to the thrust rotating speed relation and sent to an AUV control unit to be executed, and therefore stable and non-deflection direct navigation movement of the AUV is achieved. According to the method, through fusion of multi-source data and mechanical modeling, precise calculation and control over the thrust of the propeller are achieved, the steering trend in direct navigation is effectively restrained, and the motion stability and control precision of the AUV under the adsorption crawling working condition are improved.

Description

Technical Field

[0001] This invention relates to the field of motion control for autonomous underwater vehicles, and more particularly to a non-circling straight-line thrust control method for AUV adsorption crawling. Background Technology

[0002] With the increasing demand for marine resource development and underwater infrastructure maintenance, AUVs with wall adhesion and crawling capabilities have demonstrated significant application value in areas such as ship inspection, pipeline inspection, and underwater structure cleaning. However, in special scenarios such as ice-bottom operations, this technology faces significant challenges: the uneven surface of the ice bottom leads to a significant decrease in optical visual detection effectiveness, and the pressure distribution on each turbine adhering to the ice surface is uneven, resulting in asymmetrical frictional forces transmitted to the vehicle's blades. Currently, AUV systems typically lack sensors capable of real-time and accurate measurement of turbine adhesion forces and corresponding frictional forces. Therefore, when distributing thrust to the tail thruster, it is often impossible to dynamically adjust according to the actual ice-bottom friction conditions. The uneven thrust distribution makes it difficult for the AUV to counteract the additional rotational torque caused by frictional differences, ultimately leading to a continuous "circling" phenomenon during navigation, failing to achieve the expected stable straight-line operation goal. Summary of the Invention

[0003] This invention provides a non-circling straight-line thrust control method for AUV adsorption crawling, to overcome the problem that AUV cannot dynamically adjust according to the actual ice bottom friction conditions, and that the additional rotational torque causes the AUV to "circle" during navigation.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: A non-circling straight-line thrust control method for AUV adsorption crawling includes: S1. Collect operational status data and motion status data of the AUV during direct flight; the operational status data includes the rotational speed of the top turbine and the power data corresponding to the rotational speed; the motion status data includes the near-wall distance of the AUV's center of gravity; S2. Based on the operating status data, the turbine friction resistance of the three top turbines is calculated using the turbine module. S3. Based on the motion state data, the horizontal water resistance and the horizontal frictional resistance generated by the vertical force are calculated using the water resistance module. S4. Based on the turbine friction resistance of each top turbine, the horizontal water resistance, and the horizontal friction resistance generated by the vertical force, the force equation and torque balance equation of the AUV's non-circling straight-line motion are obtained through mechanical analysis of the AUV. S5. By using the force and torque balance equations of the AUV's non-circling straight-line motion, the target thrust of each tail thruster can be deduced. S6. Based on the target thrust of each tail thruster, the rotational speed of each tail thruster is obtained through the thrust-speed characteristic relationship, and the rotational speed of each tail thruster is sent to the control unit of the AUV to achieve straight-line movement of the AUV.

[0005] Furthermore, the steps for calculating the turbine friction resistance of the three top turbines include: S21. Based on the turbine speed, obtain the power linear fitting formula and suction linear fitting formula for each turbine at a fixed turbine speed; the power linear fitting formula and suction linear fitting formula are as follows:

[0006]

[0007] In the formula, For the first The turbine power of each turbine; For the first The turbine suction power of each turbine; For the first The distance from the near-wall surface of each turbine; For the turbine index; S22. Based on the power linear fitting formula and the turbine power of each turbine, the near-wall distance of each turbine is obtained by reverse derivation: ; S23. Substituting the near-wall distance of each turbine into the suction linear fitting formula, we obtain the formula for the relationship between turbine power and turbine suction, and thus obtain the turbine suction of each turbine, expressed as: ; S24. Based on the turbine suction of each turbine and the measured coefficient of ice surface friction, the frictional resistance of each turbine at the top is calculated, and the expression is:

[0008] In the formula, For the first The turbine friction resistance of the top turbine, and ,in, The turbine friction resistance of the first top turbine, The turbine friction resistance of the second top turbine, The turbine friction resistance of the third top turbine; The coefficient of friction of the ice surface.

[0009] Furthermore, the horizontal water resistance is calculated using the following formula, which is based on the near-wall distance of the AUV's center of gravity:

[0010] In the formula, This refers to the horizontal water resistance. The distance from the AUV's center of gravity to the near-wall surface; The horizontal frictional resistance generated by the vertical force is calculated using the following formula, which is based on the near-wall distance of the AUV's center of gravity:

[0011]

[0012] In the formula, The horizontal frictional resistance is generated by vertical force; It is a vertical force.

[0013] Furthermore, the force equations for the non-circling straight-line motion of the AUV, based on the turbine frictional resistance of each top turbine, the horizontal water resistance, and the horizontal frictional resistance generated by the vertical force, are obtained through the static equilibrium conditions of Newton's first law, as follows: ; In the formula, The target thrust for the first tail thruster; The target thrust for the second tail thruster; The torque balance equation for the non-circling straight-line motion of the AUV, derived from the torque balance condition based on Newton's second law, is expressed as follows:

[0014] In the formula, The distance from the point of application of the turbine friction resistance of the second top turbine to the center of gravity of the AUV; The distance from the point of application of the turbine friction resistance of the third top turbine to the center of gravity of the AUV; The distance from the point of application of the target thrust of the first tail thruster to the center of gravity of the AUV; The distance from the point of application of the target thrust of the second tail thruster to the center of gravity of the AUV.

[0015] Furthermore, by using the force and torque balance equations of the AUV, the expression for the target thrust of each tail thruster can be derived as follows: ; .

[0016] Furthermore, the steps for obtaining the rotational speed of each tail thruster include: S61. By fitting the thrust-speed characteristic relationship, a fitting formula for the relationship between thrust and speed is obtained; the fitting formula for the relationship between thrust and speed is:

[0017] In the formula, For the first The rotational speed of the tail thrusters, and ,in, The rotational speed of the first tail thruster. The rotational speed of the second tail thruster; For the first The target thrust of each tail thruster, and ; S62. Based on the target thrust of each tail thruster, the thrust-rotation speed fitting formula is reversed to obtain the tail thruster's rotational speed; the expression for the reversed thrust-rotation speed fitting formula is: .

[0018] Beneficial effects: This invention provides a non-circling straight-line thrust control method for AUV adsorption and crawling. By calculating the frictional resistance of the top turbine due to differences in speed, power, and uneven wall conditions in real time, and incorporating it together with horizontal water resistance into the mechanical balance analysis, the method can accurately quantify the disturbance torque that causes AUV yaw. Based on this, the target thrust of the tail thruster that can actively counteract this torque is calculated in reverse, thereby eliminating the unbalanced torque that causes circling at the source and ensuring that the AUV travels stably and straight along the expected trajectory during the adsorption and crawling process. By establishing and solving the force and torque balance equations, a thrust distribution scheme is proposed in advance. This model-based feedforward control strategy can compensate for time-varying disturbances in real time, avoiding the inherent lag, continuous oscillation and excessive energy consumption of traditional feedback control, thus improving control quality and overall system energy efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of the non-circling straight-line thrust method of the present invention; Figure 2 This is a simplified diagram of AUV adsorption near the ice surface in an embodiment of the present invention; Figure 3 This is an AUV operation status monitoring screen in an embodiment of the present invention. Figure 4 This is a force diagram of the AUV in the Gx direction during straight flight in an embodiment of the present invention; Figure 5 This is a torque analysis diagram of the AUV around Gz in an embodiment of the present invention; Figure 6 This is a graph showing the turbine suction force and power consumption at different distances under a fixed rotational speed in an embodiment of the present invention; Figure 7 This is a diagram showing the air resistance of AUVs at different spacings in an embodiment of the present invention; Figure 8 This is a vertical force diagram of AUV navigation under different spacing conditions in an embodiment of the present invention; Figure 9 This is a diagram showing the main thrust characteristics of the AUV in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This embodiment provides a non-circling straight-line thrust control method for AUV adsorption crawling, such as... Figure 1 As shown, it includes: S1. Collect operational status data and motion status data of the AUV during direct flight; the operational status data includes the rotational speed of the top turbine and the power data corresponding to the rotational speed; the motion status data includes the near-wall distance of the AUV's center of gravity; S2. Based on the operating status data, the turbine friction resistance of the three top turbines is calculated using the turbine module. S3. Based on the motion state data, the horizontal water resistance and the horizontal frictional resistance generated by the vertical force are calculated using the water resistance module. S4. Based on the turbine friction resistance of each top turbine, the horizontal water resistance, and the horizontal friction resistance generated by the vertical force, the force equation and torque balance equation of the AUV's non-circling straight-line motion are obtained through mechanical analysis of the AUV. S5. By using the force and torque balance equations of the AUV's non-circling straight-line motion, the target thrust of each tail thruster can be deduced. S6. Based on the target thrust of each tail thruster, the rotational speed of each tail thruster is obtained through the thrust-speed characteristic relationship, and the rotational speed of each tail thruster is sent to the control unit of the AUV to achieve straight-line movement of the AUV.

[0023] In this embodiment, the AUV is equipped with a turbine module, an ice blade module, and a vertical thruster module on one side of the ice surface; the AUV is equipped with a water resistance module at the front end; and the AUV is equipped with a propulsion module at the rear end. The turbine module includes a first top turbine, a second top turbine, and a third top turbine. The first top turbine is located in the middle of the front of the AUV, and the second and third top turbines are located at the left and right ends of the rear of the AUV, respectively. The turbine module is used to adjust the speed and power of the turbine to obtain the suction force of the turbine. The ice blade module includes a first ice blade and a second ice blade, which are respectively located at the left and right ends of the middle of the AUV; the ice blade module is used to enable the AUV to glide on the ice surface. The vertical thruster module includes a first vertical thruster, a second vertical thruster, and a third vertical thruster. The first and second vertical thrusters are respectively located at the left and right ends of the front of the AUV, and the third vertical thruster is located in the middle of the rear of the AUV. The vertical thrusters are used to generate vertical force on the AUV. The water resistance module includes a first resistance sensor for calculating horizontal water resistance and vertical force; The propulsion module includes a first tail thruster and a second tail thruster, which are respectively disposed on the left and right sides of the tail of the AUV; the propulsion module is used to generate thrust for the AUV to move forward; When AUVs are adsorbed under ice, such as Figure 2 As shown, the AUV relies on the suction of the turbine to adhere to the ice surface, and then relies on the thrust of the two tail thrusters to overcome the frictional resistance of the adhesion, thus enabling the AUV to glide on the ice surface.

[0024] Specifically, such as Figure 3 As shown, the operating status data and motion status data are collected through the AUV operating status monitoring screen; the left side of the figure shows the monitoring screen of the turbine suction cup, the middle side shows the monitoring screen of the thruster, and the right side shows the AUV speed monitoring screen.

[0025] Preferably, the step of calculating the turbine friction resistance of the three top turbines includes: S21. Based on the turbine speed, via, as follows Figure 6 The relationships between the power and the near-wall distance of each turbine, as well as the relationship between the suction force and the near-wall distance of each turbine, are shown. Linear fitting formulas for the power and suction force of each turbine at a fixed turbine speed are obtained. These linear fitting formulas are as follows:

[0026]

[0027] In the formula, For the first The turbine power of each turbine; For the first The turbine suction power of each turbine; For the first The distance from the near-wall surface of each turbine; For the turbine index; S22. Based on the power linear fitting formula and the turbine power of each turbine, the near-wall distance of each turbine is obtained by reverse derivation: ; S23. Substituting the near-wall distance of each turbine into the suction linear fitting formula, we obtain the formula for the relationship between turbine power and turbine suction, and thus obtain the turbine suction of each turbine, expressed as: ; S24. Based on the turbine suction of each turbine and the measured coefficient of ice surface friction, the frictional resistance of each turbine at the top is calculated, and the expression is:

[0028] In the formula, For the first The turbine friction resistance of the top turbine, and ,in, The turbine friction resistance of the first top turbine, The turbine friction resistance of the second top turbine, The turbine friction resistance of the third top turbine; The coefficient of friction of the ice surface.

[0029] Preferably, through, as Figure 7 The relationship between water resistance and near-wall avoidance distance is shown. The horizontal water resistance is calculated using the following formula, which is based on the near-wall distance from the AUV's center of gravity:

[0030] In the formula, This refers to the horizontal water resistance. The distance from the AUV's center of gravity to the near-wall surface; The horizontal frictional resistance generated by the vertical force is calculated using the following formula, which is based on the near-wall distance of the AUV's center of gravity:

[0031]

[0032] In the formula, The horizontal frictional resistance is generated by vertical force; It is a vertical force.

[0033] In this embodiment, the above formula is obtained by fitting the vertical force relationship of the AUV at different near-wall distances; the vertical force relationship of the AUV at different near-wall distances is as follows: Figure 8 As shown.

[0034] Specifically, such as Figure 4 As shown, in the force diagram along the Gx direction of straight flight, a carrier coordinate system Gxyz is established; where Gx is the longitudinal axis of the carrier, pointing rearward, Gy is pointing to the port side, and Gz is vertically downward; where label 1 represents the first top turbine, labels 3 and 4 represent the second and third top turbines respectively; label 2 represents the center of gravity G of the AUV; labels 5 and 6 represent the second and first tail thrusters respectively; where, The target thrust for the first tail thruster, The target thrust for the second tail thruster; , , These are the turbine friction resistance of the first top turbine, the turbine friction resistance of the second top turbine, and the turbine friction resistance of the third top turbine. The direction of the turbine friction resistance is opposite to the straight-line direction of the AUV. Water resistance, in the opposite direction to the AUV's direct flight direction; It is the horizontal frictional resistance generated by vertical force; each force is distributed horizontally along the AUV's navigation direction, and together they affect the mechanical balance in the Gx direction. like Figure 5 As shown, in the moment analysis diagram around Gz, a carrier coordinate system Gxyz is established; where Gx is the longitudinal axis of the carrier, pointing rearward, Gy is pointing towards the port side, and Gz is vertically downward; where label 1 represents the first top turbine, labels 3 and 4 represent the second and third top turbines respectively, label 2 represents the center of gravity G of the AUV, and labels 5 and 6 represent the second and first tail thrusters respectively; Indicates the first top turbine The distance from the turbine frictional resistance to the center of gravity; Indicates the second top turbine The horizontal distance from the turbine frictional resistance to the center of gravity Indicates the third top turbine The horizontal distance from the turbine frictional resistance to the center of gravity Indicates the target thrust of the first tail thruster Horizontal distance to the center of gravity Indicates the target thrust of the second tail thruster The horizontal distance to the center of gravity.

[0035] Preferably, the force equation for the non-circling straight-line motion of the AUV, based on the above force analysis, and according to the turbine friction resistance of each top turbine, the horizontal water resistance, and the horizontal friction resistance generated by the vertical force, is obtained through the static equilibrium condition of Newton's first law, as follows:

[0036] In the formula, The target thrust for the first tail thruster; The target thrust for the second tail thruster; The torque balance equation for the non-circling straight-line motion of the AUV, derived from the torque balance condition based on Newton's second law, is expressed as follows:

[0037] In the formula, The distance from the point of application of the turbine friction resistance of the second top turbine to the center of gravity of the AUV; The distance from the point of application of the turbine friction resistance of the third top turbine to the center of gravity of the AUV; The distance from the point of application of the target thrust of the first tail thruster to the center of gravity of the AUV; The distance from the point of application of the target thrust of the second tail thruster to the center of gravity of the AUV.

[0038] Specifically, the static equilibrium condition of Newton's first law and the torque equilibrium condition derived from Newton's second law are existing technologies available to those skilled in the art, and will not be elaborated here.

[0039] Preferably, the expression for the target thrust of each tail thruster can be derived by using the force and torque balance equations of the AUV: ; .

[0040] Preferably, the step of obtaining the rotational speed of each tail thruster includes: S61, via such Figure 9 The thrust-speed characteristic relationship is fitted to obtain a fitting formula for the relationship between thrust and speed; the fitting formula for the relationship between thrust and speed is:

[0041] In the formula, For the first The rotational speed of the tail thrusters, and ,in, The rotational speed of the first tail thruster. The rotational speed of the second tail thruster; For the first The target thrust of each tail thruster, and ; S62. Based on the target thrust of each tail thruster, the thrust-rotation speed fitting formula is reversed to obtain the tail thruster's rotational speed; the expression for the reversed thrust-rotation speed fitting formula is: .

[0042] The present invention has the following beneficial effects: This invention discloses a non-circling straight-line thrust control method for AUV adsorption and crawling. By calculating the frictional resistance of the top turbine due to differences in speed, power, and uneven wall conditions in real time, and incorporating it together with horizontal water resistance into the mechanical balance analysis, the method can accurately quantify the disturbance torque that causes AUV yaw. Based on this, the method can reverse-calculate the target thrust of the tail thruster that can actively counteract this torque, thereby eliminating the unbalanced torque that causes circling at the source and ensuring that the AUV travels stably and straight along the expected trajectory during the adsorption and crawling process. By establishing and solving the force and torque balance equations, a thrust distribution scheme is proposed in advance. This model-based feedforward control strategy can compensate for time-varying disturbances in real time, avoiding the inherent lag, continuous oscillation and excessive energy consumption of traditional feedback control, thus improving control quality and overall system energy efficiency.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-circling straight-line thrust control method for AUV adsorption crawling, characterized in that, include: S1. Collect operational status data and motion status data of the AUV during direct flight; the operational status data includes the rotational speed of the top turbine and the power data corresponding to the rotational speed; the motion status data includes the near-wall distance of the AUV's center of gravity; S2. Based on the operating status data, the turbine friction resistance of the three top turbines is calculated using the turbine module. S3. Based on the motion state data, the horizontal water resistance and the horizontal frictional resistance generated by the vertical force are calculated using the water resistance module. S4. Based on the turbine friction resistance of each top turbine, the horizontal water resistance, and the horizontal friction resistance generated by the vertical force, the force equation and torque balance equation of the AUV's non-circling straight-line motion are obtained through mechanical analysis of the AUV. S5. By using the force and torque balance equations of the AUV's non-circling straight-line motion, the target thrust of each tail thruster can be deduced. S6. Based on the target thrust of each tail thruster, the rotational speed of each tail thruster is obtained through the thrust-speed characteristic relationship, and the rotational speed of each tail thruster is sent to the control unit of the AUV to achieve straight-line movement of the AUV.

2. The non-circling straight-line thrust control method for AUV adsorption crawling according to claim 1, characterized in that, The steps for calculating the turbine friction resistance of the three top turbines include: S21. Based on the turbine speed, obtain the power linear fitting formula and suction linear fitting formula for each turbine at a fixed turbine speed; the power linear fitting formula and suction linear fitting formula are as follows: In the formula, For the first The turbine power of each turbine; For the first The turbine suction power of each turbine; For the first The distance from the near-wall surface of each turbine; For the turbine index; S22. Based on the power linear fitting formula and the turbine power of each turbine, the near-wall distance of each turbine is obtained by reverse derivation: ； S23. Substituting the near-wall distance of each turbine into the suction linear fitting formula, we obtain the formula for the relationship between turbine power and turbine suction, and thus obtain the turbine suction of each turbine, expressed as: ； S24. Based on the turbine suction of each turbine and the measured coefficient of ice surface friction, the frictional resistance of each turbine at the top is calculated, and the expression is as follows: In the formula, For the first The turbine friction resistance of the top turbine, and ,in, The turbine friction resistance of the first top turbine, The turbine friction resistance of the second top turbine, The turbine friction resistance of the third top turbine; The coefficient of friction of the ice surface.

3. The non-circling straight-line thrust control method for AUV adsorption crawling according to claim 1, characterized in that, The horizontal water resistance is calculated using the following formula, which is based on the near-wall distance from the AUV's center of gravity: In the formula, This refers to the horizontal water resistance. The distance from the AUV's center of gravity to the near-wall surface; The horizontal frictional resistance generated by the vertical force is calculated using the following formula, which is based on the near-wall distance of the AUV's center of gravity: In the formula, The horizontal frictional resistance is generated by vertical force; It is a vertical force.

4. The non-circling straight-line thrust control method for AUV adsorption crawling according to claim 1, characterized in that, The force equations for the non-circling straight-line motion of the AUV, based on the turbine frictional resistance of each top turbine, the horizontal water resistance, and the horizontal frictional resistance generated by the vertical force, are obtained through the static equilibrium conditions of Newton's first law, as follows: In the formula, The target thrust for the first tail thruster; The target thrust for the second tail thruster; The torque balance equation for the non-circling straight-line motion of the AUV, derived from the torque balance condition based on Newton's second law, is expressed as follows: In the formula, The distance from the point of application of the turbine friction resistance of the second top turbine to the center of gravity of the AUV; The distance from the point of application of the turbine friction resistance of the third top turbine to the center of gravity of the AUV; The distance from the point of application of the target thrust of the first tail thruster to the center of gravity of the AUV; The distance from the point of application of the target thrust of the second tail thruster to the center of gravity of the AUV.

5. The non-circling straight-line thrust control method for AUV adsorption crawling according to claim 1, characterized in that, By using the force and torque balance equations of the AUV, the expression for the target thrust of each tail thruster can be derived as follows: ； 。 6. The non-circling straight-line thrust control method for AUV adsorption crawling according to claim 1, characterized in that, The steps to obtain the rotational speed of each tail thruster include: S61. By fitting the thrust-speed characteristic relationship, a fitting formula for the relationship between thrust and speed is obtained; the fitting formula for the relationship between thrust and speed is: In the formula, For the first The rotational speed of the tail thrusters, and ,in, The rotational speed of the first tail thruster. The rotational speed of the second tail thruster; For the first The target thrust of each tail thruster, and ; S62. Based on the target thrust of each tail thruster, the thrust-rotation speed fitting formula is reversed to obtain the tail thruster's rotational speed; the expression for the reversed thrust-rotation speed fitting formula is: 。

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