A method for fixed-point control of an AUV under horizontal plane under-actuation
By constructing a linear observation model of water flow velocity and dynamically switching control modes, the problem of fixed-point positioning under underactuated conditions on the horizontal plane of AUVs was solved, achieving stable fixed-point positioning with long duration and high precision. It is applicable to different types of AUVs and water areas, and features fast speed, low energy consumption, and high robustness.
Patent Information
- Application Number
- CN202611288893.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-24
- Publication Date
- 2026-11-06
AI Technical Summary
After the AUV's horizontal auxiliary thruster was cut off, the AUV lost its ability to achieve full-drive fixed-point control in the horizontal plane, affecting the execution of precision operation and fixed-point monitoring tasks.
By constructing a linear observation model of water flow velocity, water flow information in the region is estimated, and the heading closed-loop and position closed-loop control modes are dynamically switched to achieve fixed-point positioning of the AUV in underactuated state.
It achieves long-term, high-precision, stable positioning of AUVs under underactuated conditions, and has fast, low-energy positioning capabilities. It is suitable for different AUV models and water conditions, and has good real-time performance and robustness.
Smart Images
Figure CN123047564A_ABST
Abstract
Description
Technical Field
[0001] This invention generally relates to the field of autonomous motion control of AUVs, and more specifically, to a fixed-point control method for AUVs under underactuated horizontal plane. Background Technology
[0002] Currently, autonomous underwater vehicles (AUVs) are the primary vehicles and tools used in various fields such as underwater target detection, hydrological observation, and deep-sea topographic surveying. With the increasing diversity and complexity of mission requirements, more stringent design requirements have been placed on the mission payload and overall structural layout of AUVs. Therefore, in necessary situations, unconventional AUV structural designs will be implemented at the expense of conventional overall structural layouts.
[0003] In AUV design inputs, specific indicators are typically specified for the AUV's mass, size, range, and mission capabilities. However, when the internal vacancy rate of the AUV reaches a bottleneck and still cannot meet the design input requirements, it is necessary to cut structural components that are not essential or have alternative solutions. In small and medium-sized AUV structures, auxiliary thrusters are generally through-type. In large AUV structures, there are two types of auxiliary thrusters: through-type and coaxial symmetrical dual auxiliary thrusters. This structure causes a significant loss of usable space in the AUV structure. To achieve the preset goals, auxiliary thrusters will be the primary structural components to be cut.
[0004] However, when a conventional auxiliary thruster structure is modified, the functionality of that component faces significant challenges. Auxiliary thrusters are generally used in missions involving AUV hovering and positioning, which is a crucial component of navigation control technology. The accuracy of hovering and positioning directly impacts the execution results of tasks such as fine-tuning, point-to-point monitoring, and silent reconnaissance. Modifying a single AUV's horizontal auxiliary thruster results in the AUV lacking full-drive point-to-point positioning capability in the horizontal plane. To address this issue, this invention designs a point-to-point positioning method for AUVs in under-actuated horizontal conditions. By acquiring water flow information and implementing different motion control strategies in different regions, the AUV can still resist external disturbances and achieve equilibrium in under-actuated mode, enabling long-duration, high-precision, stable point-to-point positioning operations. Summary of the Invention
[0005] According to the present invention, a positioning and control scheme for AUVs under underactuated in the horizontal plane is provided. This scheme, while designing the AUV's horizontal plane underactuated structure under overall mission constraints, ensures that the AUV still possesses the capability for positioning and control in tasks such as precision operation, fixed-point monitoring, and silent latent detection. Based on the design concept of this invention, the scheme can dynamically switch between yaw control and lateral movement control modes to quickly, efficiently, and stably complete positioning and control functions, achieving long-term, high-precision, and stable positioning and control operations, adapting to different AUV propeller distributions and varying water conditions.
[0006] This invention provides a method for fixed-point positioning under underactuated conditions in the horizontal plane of an AUV. The method includes: Acquire AUV motion status data and target position; wherein, the AUV motion status data includes: AUV turning radius, AUV speed, and AUV position; Construct a linear observation model for water flow velocity; use the linear observation model for water flow velocity to estimate water flow information within the region; Calculate the braking distance of the AUV from its speed to zero; then, based on the braking distance and the AUV's turning radius, calculate the distance switching threshold. Calculate the target distance based on the AUV's location and the target's location; If the target distance is greater than the distance switching threshold, the AUV will be controlled using a heading closed-loop method based on the water flow information in the area, the AUV's position, the AUV's turning radius, and the distance switching threshold; otherwise, a position closed-loop method will be used to control the AUV to hover and maintain its position at a fixed point.
[0007] Furthermore, estimating water flow information within the region using the linear observation model of water flow velocity includes: The linear observation model of water flow velocity was solved using the least squares method to obtain the eastward and northward water flow velocities. The direction of water flow is calculated based on the average of the eastward and northward water flow velocities.
[0008] Furthermore, the linear observation model for water flow velocity is as follows:
[0009]
[0010]
[0011]
[0012] in, For measurement data matrix; The matrix to be estimated; For the transformation matrix, The pitch angle of the AUV; The heading angle of the AUV; The roll angle of the AUV; The rightward velocity of the AUV relative to the bottom in the motion coordinate system; This is the transformation matrix; The northward velocity of the water flow in the geodetic coordinate system; The eastward velocity of the water flow in the geodetic coordinate system; The forward convective velocity of the AUV in the moving coordinate system; Let be the rightward convective velocity of the AUV in the moving coordinate system.
[0013] Furthermore, the formula for calculating the distance switching threshold is:
[0014] in, Distance switching threshold; This is the first distance coefficient; Braking distance; This is the second distance coefficient; The radius of rotation of the AUV.
[0015] Furthermore, the method of controlling AUV navigation using a closed-loop heading mechanism based on regional water flow information, AUV position, AUV turning radius, and distance switching threshold includes: Calculate the buffer location based on the water flow information, AUV turning radius, and distance switching threshold within the area; The distance between the AUV position and the buffer position is used as the buffer distance; Use LOS to obtain the target heading; A preset buffer distance threshold is set; if the buffer distance is less than the buffer distance threshold, the AUV is controlled to travel toward the target heading.
[0016] Furthermore, controlling the AUV to travel toward the target heading includes: The LOS algorithm is used to perform a heading closed loop on the AUV to obtain the expected value of the horizontal plane turning control quantity; Based on the expected value of the horizontal plane yaw control variable, the propeller speed is calculated; Based on the propeller speed, the AUV is controlled to travel toward the target heading.
[0017] Furthermore, the heading closed-loop formula is:
[0018] in, This represents the expected value of the horizontal plane steering control quantity; The proportional coefficient in the heading PID control; This refers to the horizontal angular velocity error. The integral coefficient in the heading PID control; This is the integral of the horizontal angular velocity error; The differential coefficient in the heading PID control; The derivative of the horizontal angular velocity; The center position of the AUV in the motion coordinate system Axis coordinate values.
[0019] Furthermore, the method of using a closed-loop position control to control the AUV for fixed-point hovering and positioning includes: The position closed loop of the AUV is performed using the PID algorithm to obtain the expected value of the horizontal lateral displacement control quantity; The propeller speed is calculated based on the expected value of the horizontal plane lateral displacement control quantity. Based on the propeller speed, the AUV is controlled to perform fixed-point hovering and positioning.
[0020] Furthermore, the formula for the position closed loop is:
[0021] in, This represents the desired value of the horizontal plane lateral displacement control quantity. This refers to the proportional coefficient in the PID control of horizontal plane position. This refers to the rightward velocity error; The integral coefficient in the PID control of horizontal plane position; This is the integral of the rightward velocity error; These are the differential coefficients in the PID control of horizontal plane position; This is the rightward velocity derivative.
[0022] Furthermore, the formula for calculating the propeller speed is:
[0023] in, The propeller speed is the heading direction. The diameter of the propeller; For fluid density; This is the torque coefficient; The expected value of the input control quantity.
[0024] Compared with the prior art, the present invention has the following beneficial technical effects: 1. The method of this invention enables underactuated AUVs to possess the capability for AUV positioning and control, suitable for tasks such as precision operation, fixed-point monitoring, and silent latent detection. Based on the design concept of this invention, it can dynamically switch between yaw control and lateral movement control modes to quickly, efficiently, and stably complete positioning and control functions, achieving long-term, high-precision, and stable positioning and control operations, adapting to different AUV propeller distributions and varying water conditions. It possesses advantages such as strong versatility, low safety risk, simple conversion, and high stability.
[0025] 2. The method of the present invention has a fast calculation speed and low resource consumption. It can output control allocation values in real time at a high frequency in actual tasks. Through the rapid response of the AUV auxiliary thruster propeller, it can realize the control of this degree of freedom in a fast closed loop, achieve the purpose of high-precision fixed-point control, and has good real-time performance and robustness.
[0026] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description
[0027] The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein: Figure 1 A flowchart of a fixed-point positioning method for AUV under horizontal plane underactuation according to an embodiment of the present invention is shown; Figure 2 A flowchart illustrating water flow information within an estimated region according to an embodiment of the present invention is shown; Figure 3 A flowchart illustrating AUV navigation control using a heading closed-loop method according to an embodiment of the present invention is shown; Figure 4 A flowchart illustrating the control of an AUV to travel to a target location according to an embodiment of the present invention is shown; Figure 5 A flowchart illustrating the control of an AUV for stationary hovering control according to an embodiment of the present invention is shown. Detailed Implementation
[0028] 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, and 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.
[0029] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.
[0030] In this invention, motion state data and target position are first collected; and water flow information is estimated based on the collected data. Next, a distance switching threshold is calculated, and the current target distance is calculated in real time based on the AUV's position and the target position. Finally, the target distance is compared with the distance switching threshold to complete mode-specific control: when the target distance is greater than the threshold, water flow information, AUV position, turning radius, and switching threshold are integrated, and heading closed-loop control is used to navigate the AUV toward the target; when the target distance is less than or equal to the threshold, position closed-loop control is switched to enable the AUV to hover and maintain position. In this way, fixed-point control under underactuated conditions on the horizontal plane can be achieved.
[0031] Figure 1 A flowchart of a fixed-point positioning method for AUV horizontal plane under-actuation according to an embodiment of the present invention is shown.
[0032] The method includes S101~S105: S101. Acquire AUV motion status data and target position; wherein, the AUV motion status data includes: AUV turning radius, AUV speed and AUV position.
[0033] Specifically, the turning radius of an AUV refers to the radius of the circle traced by its center of mass during uniform, steady rotational motion. The AUV speed refers to its velocity relative to the seawater medium. The AUV position refers to the three-dimensional spatial coordinates of its center of mass in a geodetic / local coordinate system. The target position refers to the spatial reference coordinates to which the AUV needs to reach.
[0034] S102. Construct a linear observation model for water flow velocity; use the linear observation model for water flow velocity to estimate water flow information in the region.
[0035] Specifically, the process of constructing the linear observation model for water flow velocity is as follows: (1) Construct a transformation matrix based on the AUV attitude angle.
[0036] Specifically, the transformation matrix is:
[0037] in, This is the transformation matrix; The pitch angle of the AUV; The heading angle of the AUV; This refers to the roll angle of the AUV.
[0038] (2) Using the AUV’s three-axis bottom velocity, AUV’s three-axis water velocity and transformation matrix, construct the displacement equation; differentiate the displacement equation to obtain the AUV’s forward velocity and AUV’s rightward velocity.
[0039] Specifically, the displacement equation is:
[0040] in, The forward velocity of the AUV relative to the ground in the motion coordinate system; The rightward velocity of the AUV relative to the bottom in the motion coordinate system; This is the transformation matrix; The northward velocity of the water flow in the geodetic coordinate system; The eastward velocity of the water flow in the geodetic coordinate system; The forward convective velocity of the AUV in the moving coordinate system; Let be the rightward convective velocity of the AUV in the moving coordinate system.
[0041] (3) Based on the forward velocity, rightward velocity, and transformation matrix of the AUV, a linear observation model for water flow velocity is constructed. The linear observation model for water flow velocity is as follows:
[0042]
[0043]
[0044]
[0045] in, For measurement data matrix; The matrix to be estimated; For the transformation matrix, The pitch angle of the AUV; The heading angle of the AUV; The roll angle of the AUV; The rightward velocity of the AUV relative to the bottom in the motion coordinate system; This is the transformation matrix; The northward velocity of the water flow in the geodetic coordinate system; The eastward velocity of the water flow in the geodetic coordinate system; The forward convective velocity of the AUV in the moving coordinate system; Let be the rightward convective velocity of the AUV in the moving coordinate system.
[0046] The linear water flow velocity observation model established in this embodiment can observe the external environmental disturbances during the current movement of the AUV in real time. The ocean current direction during the current movement of the AUV can be further derived through the observation model, providing key information input for the fixed-point control of the underactuated AUV on the horizontal plane.
[0047] In this embodiment, as Figure 2 As shown, the estimation of water flow information within the region using the linear observation model of water flow velocity includes S201~S202: S201. Solve the linear observation model of water flow velocity using the least squares method to obtain the eastward water flow velocity. and the speed of the northward water flow The least squares method is a well-known existing technique and will not be elaborated upon here.
[0048] As some optional implementations of this embodiment, the eastward and northward water flow velocities must meet the following conditions:
[0049] S202. Calculate the water flow direction information based on the average of the eastward and northward water flow velocities. The specific calculation formula is as follows:
[0050] in, Indicates the direction of water flow; The function automatically determines the quadrant of a location point based on input information and calculates the angle value. The output range is [range missing]. ; The function normalizes the output information to the range. Inside; The speed of the eastward water flow; This represents the speed of the northward-flowing water.
[0051] This embodiment utilizes the aforementioned linear water flow velocity observation model to estimate water flow information within the region, providing crucial information input for point-to-point positioning of underactuated AUVs on the horizontal plane. The AUV can be controlled to the optimal heading in advance, significantly reducing the position control convergence time and improving the efficiency of point-to-point positioning of underactuated AUVs on the horizontal plane.
[0052] S103. Calculate the braking distance of the AUV from its initial speed to zero; then, based on the braking distance and the AUV's turning radius, calculate the distance switching threshold. The braking distance refers to the taxiing distance of the AUV after its initial speed has decreased to zero.
[0053] In this embodiment, the formula for calculating the distance switching threshold is:
[0054] in, Distance switching threshold; This is the first distance coefficient; Braking distance; This is the second distance coefficient; The radius of rotation of the AUV.
[0055] Specifically, the first distance coefficient Generally, it is greater than 1; the larger the value, the safer it is for AUVs, but the slower the convergence speed; the second distance coefficient This is related to the angle between the current AUV's heading and the direction of the ocean current; the larger the angle, the more necessary it is to... The larger the value, the safer it is for AUVs, but the slower the convergence speed.
[0056] S104. Calculate the target distance based on the AUV position and the target position. Specifically, input the AUV position and the target position into the existing two-point distance formula to obtain the buffer distance.
[0057] S105. If the target distance is greater than the distance switching threshold, the AUV will be controlled to navigate using a heading closed-loop method based on the water flow information in the area, the AUV's position, the AUV's turning radius, and the distance switching threshold; otherwise, the AUV will be controlled to hover at a fixed point using a position closed-loop method.
[0058] In this embodiment, as Figure 3 As shown, the method of controlling AUV navigation using a closed-loop heading mechanism based on regional water flow information, AUV position, AUV turning radius, and distance switching threshold includes S301~S304: S301. Based on the water flow information within the area, the AUV turning radius, and the distance switching threshold, calculate the buffer location, including: (1) Obtain the direction of water flow based on the water flow information in the area.
[0059] (2) Extend along the direction of water flow The point corresponding to the distance is used as a buffer position for navigation planning. Distance switching threshold; The radius of rotation of the AUV.
[0060] S302. Use the distance between the AUV position and the buffer position as the buffer distance. Specifically, input the AUV position and the buffer position into the existing two-point distance formula to obtain the buffer distance.
[0061] S303. Obtain the target heading using LOS (Line-of-Sight). LOS is an existing algorithm in this field. Based on relevant input information such as ship length, the latitude and longitude of the starting and ending points of the tracked line segment, the current AUV position, and heading, the algorithm can autonomously calculate the target heading.
[0062] S304, Preset buffer distance threshold is If the buffer distance is less than the buffer distance threshold, the AUV is controlled to travel towards the target location.
[0063] Specifically, when the AUV enters the position closed-loop control mode, the AUV has a certain initial position error tolerance capability, meaning the distance between the AUV's initial position and the buffer position does not necessarily have to be zero. Therefore, a buffer distance threshold is preset. In this embodiment, the buffer distance threshold = , The radius of rotation of the AUV.
[0064] In this embodiment, as Figure 4 As shown, controlling the AUV to travel to the target location includes steps S401-S403: S401. Use the LOS algorithm to perform a heading closed loop on the AUV to obtain the expected value of the horizontal plane turning control quantity.
[0065] In this embodiment, the heading closed-loop formula is:
[0066] in, This represents the expected value of the horizontal plane steering control quantity; The proportional coefficient in the heading PID control; This refers to the horizontal angular velocity error. The integral coefficient in the heading PID control; This is the integral of the horizontal angular velocity error; The differential coefficient in the heading PID control; The derivative of the horizontal angular velocity, The center position of the AUV in the motion coordinate system axis coordinate values, .
[0067] This embodiment is based on closed-loop control of the heading, so that in the position closed-loop mode, the forward thrust and the force generated by the water flow are basically canceled out, reducing the heading oscillation time.
[0068] S402. Based on the expected value of the horizontal plane steering control variable, calculate the propeller speed. Specifically, input the expected value of the horizontal plane steering control variable into the formula for calculating the propeller speed to obtain the propeller speed.
[0069] In this embodiment, the formula for calculating the propeller speed is:
[0070] in, The propeller speed is the heading direction. The diameter of the propeller; For fluid density; This is the torque coefficient; Here, the desired value of the input control quantity is... = , This represents the expected value of the horizontal plane steering control variable.
[0071] This embodiment uses observation error to perform closed-loop control on directly related actuators, which can quickly reduce control error and achieve closed-loop position control.
[0072] S403: Based on the propeller speed, control the AUV to travel toward the target heading.
[0073] This embodiment is based on closed-loop control of the heading, so that in the position closed-loop mode, the forward thrust and the force generated by the water flow are basically canceled out, the lateral distance is small and easy to adjust, the heading oscillation time is reduced, and the fixed-point control closed-loop speed is accelerated.
[0074] This embodiment fully considers the impact of the AUV's position status outside the area corresponding to the set distance switching threshold on the fixed-point control method, reducing the risk that the method may not be applicable due to different AUV performance, and enabling the AUV to switch control strategies in various modes according to the design process to achieve the purpose of fixed-point control.
[0075] In this embodiment, as Figure 5 As shown, the method of using a closed-loop position control to control the AUV for fixed-point hovering and positioning includes S501~S503: S501. The AUV is closed-loop position control using the PID (Proportional-Integral-Derivative) algorithm to obtain the expected value of the horizontal lateral displacement control quantity.
[0076] In this embodiment, the formula for the position closed loop is:
[0077] in, This represents the desired value of the horizontal plane lateral displacement control quantity. This refers to the proportional coefficient in the PID control of horizontal plane position. This refers to the rightward velocity error; The integral coefficient in the PID control of horizontal plane position; This is the integral of the rightward velocity error; These are the differential coefficients in the PID control of horizontal plane position; This is the rightward velocity derivative.
[0078] This embodiment is based on position closed-loop control under underactuated AUV horizontal plane control. It combines real-time acquired data to calculate the control error and completes the calculation of the actuator control quantity through PID control method, thereby realizing fixed-point control at a specified position.
[0079] S502. Based on the expected value of the horizontal plane lateral displacement control quantity, calculate the propeller speed. Input the expected value of the horizontal plane lateral displacement control quantity into the formula for calculating the propeller speed to obtain the propeller speed.
[0080] In this embodiment, the formula for calculating the propeller speed is:
[0081] in, The propeller speed is the heading direction. The diameter of the propeller; For fluid density; This is the torque coefficient; Here, the desired value of the input control quantity is... = , This represents the expected value of the horizontal plane lateral displacement control quantity.
[0082] S503: Based on the propeller speed, control the AUV to perform fixed-point hovering control.
[0083] This embodiment is based on closed-loop position control under underactuated AUV horizontal plane control. Combined with the rapid response of the actuator, it can perform fixed-point control at a designated location and complete related data acquisition, marine information collection and other operations as needed.
[0084] As some optional implementation methods of this embodiment, for any hovering target point, the process from step S101 to step S105 is carried out. Taking into account factors such as AUV speed, distance to the hovering target point and minimum turning radius, the working time is set, and the fixed-point control task under horizontal under-drive can be completed.
[0085] According to embodiments of the present invention, the following advantages are achieved compared to the prior art: (1) This invention has strong universality, simple conversion, and excellent stability: The method of this invention enables underactuated AUVs to have the ability to perform AUV positioning and control methods for tasks such as fine operation, fixed-point monitoring, and silent latent detection. It can dynamically switch between yaw control and lateral movement control modes according to the design concept of this invention, based on the distribution of different AUV thruster models and different water conditions, to quickly, with low energy consumption, and stably complete the positioning and control function, achieving long-term, high-precision, and stable positioning and control operations. It has the advantages of strong universality, low safety risk, simple conversion, and strong stability.
[0086] (2) The present invention has good real-time performance and strong robustness: The method of the present invention has a fast calculation speed and low resource consumption. It can output control allocation values in real time at high frequency in actual tasks. Through the rapid response of the AUV auxiliary thruster propeller, the control of this degree of freedom can be quickly closed-loop, achieving high-precision fixed-point control. It has good real-time performance and robustness.
[0087] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to the present invention.
[0088] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.
[0089] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A method for fixed-point positioning under underactuated conditions on the horizontal plane of an AUV, characterized in that, include: Acquire AUV motion status data and target position; wherein, the AUV motion status data includes: AUV turning radius, AUV speed, and AUV position; Construct a linear observation model for water flow velocity; use the linear observation model for water flow velocity to estimate water flow information within the region; Calculate the braking distance of the AUV from its speed to zero; then, based on the braking distance and the AUV's turning radius, calculate the distance switching threshold. Calculate the target distance based on the AUV's location and the target's location; If the target distance is greater than the distance switching threshold, the AUV will be controlled using a heading closed-loop method based on the water flow information in the area, the AUV's position, the AUV's turning radius, and the distance switching threshold; otherwise, a position closed-loop method will be used to control the AUV to hover and maintain its position at a fixed point.
2. The method according to claim 1, characterized in that, The estimation of water flow information within the region using the linear observation model of water flow velocity includes: The linear observation model of water flow velocity was solved using the least squares method to obtain the eastward and northward water flow velocities. The direction of water flow is calculated based on the average of the eastward and northward water flow velocities.
3. The method according to claim 1, characterized in that, The linear observation model for water flow velocity is as follows: in, For measurement data matrix; The matrix to be estimated; For the transformation matrix, The pitch angle of the AUV; The heading angle of the AUV; The roll angle of the AUV; The rightward velocity of the AUV relative to the bottom in the motion coordinate system; This is the transformation matrix; The northward velocity of the water flow in the geodetic coordinate system; The eastward velocity of the water flow in the geodetic coordinate system; The forward convective velocity of the AUV in the moving coordinate system; Let be the rightward convective velocity of the AUV in the moving coordinate system.
4. The method according to claim 1, characterized in that, The formula for calculating the distance handover threshold is: in, Distance switching threshold; This is the first distance coefficient; Braking distance; This is the second distance coefficient; The radius of rotation of the AUV.
5. The method according to claim 1, characterized in that, The method of controlling the AUV's directional navigation using a closed-loop approach based on regional water flow information, AUV position, AUV turning radius, and distance switching threshold includes: Calculate the buffer location based on the water flow information, AUV turning radius, and distance switching threshold within the area; The distance between the AUV position and the buffer position is used as the buffer distance; Use LOS to obtain the target heading; A preset buffer distance threshold is set; if the buffer distance is less than the buffer distance threshold, the AUV is controlled to travel toward the target heading.
6. The method according to claim 5, characterized in that, The control of the AUV to travel toward the target heading includes: The LOS algorithm is used to perform a heading closed loop on the AUV to obtain the expected value of the horizontal plane turning control quantity; Based on the expected value of the horizontal plane yaw control variable, the propeller speed is calculated; Based on the propeller speed, the AUV is controlled to travel toward the target heading.
7. The method according to claim 6, characterized in that, The heading closed-loop formula is: in, This represents the expected value of the horizontal plane steering control quantity; The proportional coefficient in the heading PID control; This refers to the horizontal angular velocity error. The integral coefficient in the heading PID control; This is the integral of the horizontal angular velocity error; The differential coefficient in the heading PID control; The derivative of the horizontal angular velocity; The center position of the AUV in the motion coordinate system Axis coordinate values.
8. The method according to claim 1, characterized in that, The method of using a closed-loop position control to control the AUV for fixed-point hovering and positioning includes: The position closed loop of the AUV is performed using the PID algorithm to obtain the expected value of the horizontal lateral displacement control quantity; The propeller speed is calculated based on the expected value of the horizontal plane lateral displacement control quantity. Based on the propeller speed, the AUV is controlled to perform fixed-point hovering and positioning.
9. The method according to claim 8, characterized in that, The formula for the location-closed loop is: in, This represents the desired value of the horizontal plane lateral displacement control quantity. This refers to the proportional coefficient in the PID control of horizontal plane position. This refers to the rightward velocity error; The integral coefficient in the PID control of horizontal plane position; This is the integral of the rightward velocity error; These are the differential coefficients in the PID control of horizontal plane position; This is the rightward velocity derivative.
10. The method according to claim 6 or 8, characterized in that, The formula for calculating the propeller speed is: in, The propeller speed is the heading direction. The diameter of the propeller; For fluid density; This is the torque coefficient; The expected value of the input control quantity.