Method for underwater helicopter variable diameter screw docking based on dynamic parameter adjustment

Abstract

This invention provides a method for underwater helicopters to dock using a variable-diameter spiral based on dynamic parameter adjustment, relating to the field of underwater vehicle docking and recovery technology. The method includes: measuring the layout information of the base station after it is placed on the seabed; converting the layout information to the navigation coordinate system of the underwater helicopter to determine the target position and depth for docking; upon receiving a docking command, calculating the relative horizontal distance between the initial position and the target position; determining whether the distance exceeds a threshold; if so, the underwater helicopter travels towards the target position while continuously assessing the relative horizontal distance; if not, entering optical navigation mode and using an adaptive line-of-sight guidance law to move along a variable-diameter spiral trajectory; and dynamically adjusting its forward-looking distance based on the underwater helicopter's longitudinal error, speed, and path curvature to gradually approach the base station and complete docking. This invention effectively improves the stability and accuracy of underwater helicopter docking in complex environments.

Description

Technical Field

[0001] This invention relates to the field of underwater helicopter seabed docking and recovery technology, and in particular to an underwater helicopter variable diameter spiral docking method based on dynamic parameter adjustment. Background Technology

[0002] Subsea Docking Systems (SDS) play a crucial role in enhancing the endurance and operational efficiency of Autonomous Underwater Vehicles (AUVs). Specifically, SDS effectively supports AUVs in long-duration operations in the seabed environment while resolving key issues such as energy replenishment and data transmission. When performing complex underwater missions, AUVs typically need to return to a base station for resupply or data exchange; the success rate and efficiency of docking during this process directly determine the smooth progress of the operation. Therefore, optimizing and improving the docking process is one of the key factors in enhancing the overall operational efficiency of AUVs.

[0003] Within the AUV family, the Autonomous Underwater Helicopter (AUH) represents a new concept in submersibles. The AUH features a unique disc-shaped design and a multi-thruster layout, enabling it to achieve omnidirectional maneuverability, vertical takeoff and landing, and robust hovering during underwater operations. Especially in complex marine environments, the AUH exhibits strong maneuverability and stability, adapting to complex ocean dynamics and potential obstacles, making it a promising candidate for applications in deep-sea exploration and seabed operations.

[0004] However, existing technologies often fail to effectively cope with the dynamic changes in the marine environment, such as complex water currents and turbulence, leading to docking mission failures or low efficiency. Traditional docking methods rely on sensor positioning and guidance, which can achieve basic docking, but still struggle to guarantee the stability and accuracy of docking in complex environments. Summary of the Invention

[0005] Existing technologies often fail to effectively cope with the dynamic changes in the marine environment, particularly complex currents and turbulence, leading to docking mission failures or low efficiency. Traditional docking methods rely on sensor positioning and guidance, which, while enabling basic docking, still struggle to guarantee stability and accuracy in complex environments. To address these issues, this invention provides an underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment.

[0006] The technical solutions provided by the embodiments of the present invention are as follows:

[0007] The underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment provided in this embodiment of the invention includes:

[0008] S1: Measurement information on the deployment of the base station after it is placed on the seabed;

[0009] S2: Convert the arrangement information to the navigation coordinate system of the underwater helicopter to determine the target position and target depth of the underwater helicopter entering the dock;

[0010] S3: When a docking command is received, calculate the relative horizontal distance between the initial position of the underwater helicopter and the target position;

[0011] S4: Determine whether the relative horizontal distance is greater than the relative horizontal distance threshold; if yes, proceed to S5; otherwise, proceed to S6.

[0012] S5: Control the underwater helicopter to autonomously navigate to the target location according to the set desired speed, desired depth and desired course, and return to S4;

[0013] S6: Turn on the optical navigation light source of the base station. When the underwater helicopter detects the optical navigation light source, it enters the optical navigation mode and begins spiral docking using an adaptive line-of-sight guidance rate.

[0014] S7: Based on the longitudinal error, speed, and path curvature of the underwater helicopter, dynamically adjust the forward sight distance of the underwater helicopter;

[0015] S8: Based on the forward-looking distance, the adaptive line-of-sight guidance law is used to guide the underwater helicopter to gradually approach the base station along a variable-diameter spiral trajectory;

[0016] S9: Determine whether the relative horizontal distance is less than the first radius threshold; if so, record the current initial depth of the underwater helicopter and adjust the desired course to align with the target position;

[0017] S10: Determine whether the relative horizontal distance is less than the second radius threshold; if so, instruct the underwater helicopter to perform a descent operation;

[0018] S11: When descending to the bottom structure of the base station, determine whether the difference between the real-time pose and the desired pose of the underwater helicopter is less than a preset difference; if yes, determine that the underwater helicopter has completed docking; otherwise, proceed to S12.

[0019] S12: Cause the underwater helicopter to rise to the surface using its own buoyancy and return to S11 until the underwater helicopter completes docking.

[0020] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0021] (1) In this embodiment of the invention, autonomous navigation and adaptive trajectory guidance effectively address complex water currents and turbulence. Upon receiving the docking command, the underwater helicopter can automatically adjust its heading, depth, and speed according to the target location, ensuring stable navigation and reducing the impact of environmental factors. Furthermore, the system integrates longitudinal error, navigation speed, and path curvature information in real time to dynamically adjust the forward-looking distance, improving the robustness and accuracy of path tracking. During docking, the underwater helicopter gradually approaches the base station along a variable-diameter spiral trajectory, with the spiral radius gradually decreasing as the path changes, forming a stable and progressive three-dimensional guidance trajectory. This effectively improves the success rate and docking stability of the underwater helicopter's autonomous docking in complex marine environments.

[0022] (2) In this embodiment of the invention, the accuracy and stability of traditional sensor positioning are optimized by introducing an optical navigation light source. Especially in complex environments, the optical navigation mode can improve the reliability of positioning. At the same time, the system adjusts the desired course as it approaches the target to accurately align with the target position. By adjusting the attitude through buoyancy, the system can also self-correct when encountering attitude deviations, ensuring that the underwater helicopter can successfully complete the docking mission. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic flowchart of the underwater helicopter variable diameter spiral docking method based on dynamic parameter adjustment provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the overall docking of an underwater helicopter with a variable diameter spiral entering the dock based on dynamic parameter adjustment, provided in an embodiment of the present invention.

[0026] Figure 3 A navigation trajectory diagram of an underwater helicopter variable diameter spiral entering a dock based on dynamic parameter adjustment, provided in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of dynamic parameter adjustment provided in an embodiment of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0029] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0030] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent.

[0031] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0032] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0033] Reference manual attached Figure 1 The diagram illustrates a flow chart of the underwater helicopter variable diameter spiral docking method based on dynamic parameter adjustment provided in an embodiment of the present invention.

[0034] Reference manual attached Figure 2 This diagram illustrates the overall docking schematic of the underwater helicopter variable diameter spiral docking method based on dynamic parameter adjustment provided in an embodiment of the present invention.

[0035] Reference manual attached Figure 3 The diagram shows the navigation trajectory of an underwater helicopter with variable diameter spiral entering the dock based on dynamic parameter adjustment, as provided in an embodiment of the present invention.

[0036] Reference manual attached Figure 4 This illustrates the schematic diagram of dynamic parameter adjustment provided in an embodiment of the present invention.

[0037] This invention provides a method for underwater helicopters to enter dock using a variable-diameter spiral based on dynamic parameter adjustment. The processing flow of this method may include the following steps:

[0038] S1: Deployment information of the measurement base station after it is placed on the seabed.

[0039] A base station is a fixed or mobile facility used to support underwater equipment (such as underwater helicopters and AUVs) in carrying out their missions. It is typically located on the seabed or surface and provides essential support functions for underwater vehicles, such as energy replenishment, data exchange, communication, and positioning. Base stations are a crucial component of underwater operational systems, playing a vital role, especially in long-duration, complex operations.

[0040] Optionally, the layout information includes longitude, latitude, and depth.

[0041] In this invention, by acquiring precise base station layout information, it is possible to ensure that underwater helicopters can accurately determine their target positions. This is crucial for position matching during navigation and docking processes, reducing docking failures caused by inaccurate positioning.

[0042] S2: Convert the deployment information to the navigation coordinate system of the underwater helicopter to determine the target position and target depth of the underwater helicopter entering the dock.

[0043] In this invention, the base station layout information is converted into the underwater helicopter's position in its navigation coordinate system. This ensures that the underwater helicopter can accurately determine the target location and depth during mission execution, thereby avoiding docking failures or deviations caused by positioning errors. Furthermore, clearly defining the target location and depth allows the underwater helicopter to perform docking missions more quickly and accurately. The underwater helicopter can perform optimized path planning based on real-time calculated target points, reducing unnecessary adjustments and wasted time, and improving docking efficiency.

[0044] Furthermore, the marine environment is complex and changeable; currents, turbulence, and other environmental factors can affect positioning accuracy. By converting base station information into the underwater helicopter's own coordinate system, the underwater helicopter can better cope with dynamic changes, automatically adjust its position and course, and ensure stability.

[0045] It should be noted that the docking process is divided into three main stages, including the long-distance return stage (stage one), the spiral descent stage (stage two), and the terminal docking stage (stage three).

[0046] S3: When a docking command is received, calculate the relative horizontal distance between the initial position of the underwater helicopter and the target position.

[0047] In one possible implementation, the formula for calculating the relative horizontal distance is:

[0048]

[0049] Where d represents the relative horizontal distance, (x, y) represents the initial position of the underwater helicopter, and (cx ,c y ) indicates the target location of the base station.

[0050] It should be noted that when the horizontal distance to the target is known, the underwater helicopter can dynamically adjust its speed and heading according to changes in distance. For example, as the relative horizontal distance decreases, the underwater helicopter may slow down to ensure precise docking and avoid docking failure due to excessive speed.

[0051] In this invention, calculating the relative horizontal distance helps underwater helicopters simplify the path planning process. By knowing the distance between the current position and the target position, the underwater helicopter can quickly determine the straight-line distance between itself and the target, thereby effectively planning its forward path and reducing unnecessary navigation adjustments.

[0052] S4: Determine if the relative horizontal distance is greater than the relative horizontal distance threshold. If yes, proceed to S5. Otherwise, proceed to S6.

[0053] It should be noted that those skilled in the art can set the relative horizontal threshold value themselves, and this invention does not limit it.

[0054] S5: Control the underwater helicopter to autonomously navigate to the target location at the set desired speed, depth, and course, and return to S4.

[0055] Specifically, in Phase One, the long-distance return phase, the underwater helicopter uses USBL and INS combined navigation technology to autonomously navigate to the target docking position over a long distance, and controls its desired horizontal speed, desired depth, and desired heading angle.

[0056] USBL (Ultra-Short Baseline) is an underwater positioning technology widely used for positioning and navigation of underwater vehicles (such as AUVs and ROVs) and other underwater equipment. USBL systems utilize acoustic signals for measurement, providing high-precision positioning information in underwater environments. Its core principle is to determine the target's position by measuring the sound wave propagation time and angle between a surface-based base station and the underwater target.

[0057] INS (Inertial Navigation System) is a technology that uses inertial sensors (such as accelerometers and gyroscopes) to achieve positioning, navigation, and attitude control. INS calculates the motion state of an object by measuring its acceleration and angular velocity, thus providing real-time position, velocity, and orientation information. Unlike other navigation systems that rely on external signals (such as GPS), INS is completely autonomous and can operate in environments without external positioning signals, making it widely applicable in underwater navigation, aerospace, and vehicle navigation.

[0058] In one possible implementation, the formula for calculating the desired heading is:

[0059] ψ d1 =arctan2(c y -y,c x -x)

[0060] Where, ψ d1 represents the desired heading, and arctan represents the arctangent function.

[0061] In this invention, the combination of USBL and INS provides underwater helicopters with precise positioning and navigation information. The USBL system uses acoustic signals for positioning, accurately determining the relative position of the underwater helicopter to the target base station over long distances. Meanwhile, the INS continuously provides attitude, velocity, and position data through inertial measurement units (such as gyroscopes and accelerometers), enabling the underwater helicopter to perform autonomous navigation efficiently, especially in the absence of external reference signals, thus ensuring navigation accuracy.

[0062] S6: Activate the optical navigation light source of the base station. When the underwater helicopter detects the optical navigation light source, it enters the optical navigation mode and begins spiral docking using an adaptive line-of-sight guidance rate.

[0063] Optical navigation is a technology that uses optical sensors and image processing techniques to achieve navigation and positioning. It helps devices or vehicles (such as underwater vehicles, autonomous vehicles, and satellites) determine their position, orientation, or trajectory by analyzing optical images or light signals captured from the environment.

[0064] Among them, the Adaptive Line-of-Sight Guidance Law (ALOS) is a navigation control strategy primarily used in autonomous systems such as autonomous driving, drones, robots, and underwater vehicles. In this guidance method, the goal is to ensure the vehicle moves stably along a predetermined trajectory (usually a curved path or target location). By adjusting control parameters such as heading and speed in real time, it ensures trajectory tracking and optimizes system performance.

[0065] Specifically, when the horizontal distance between the AUH and the base station is less than the relative horizontal distance threshold, it enters Phase Two, the variable-diameter spiral descent phase. The base station turns on the light source for optical navigation, and the AUH's docking camera starts searching for and capturing the light source until it can stably see the light source. Then it switches to optical navigation mode. That is, in Phase Two and Phase Three, the AUH will use more precise optical guidance.

[0066] In this invention, when approaching a base station, the underwater helicopter can provide higher positioning accuracy using optical navigation mode than traditional sonar or other sensors. By accurately capturing the base station's light source, the underwater helicopter can more accurately determine its relative position and attitude with the base station, reducing errors and improving the accuracy of the docking process.

[0067] S7: Dynamically adjusts the forward-looking distance of the underwater helicopter by combining its longitudinal error, speed, and path curvature.

[0068] Look-ahead distance is a crucial parameter in navigation systems used to describe how vehicles, robots, or underwater vehicles (such as AUVs and AUHs) predict the target path based on current state and environmental information during path tracking. Look-ahead distance refers to the range of distances ahead along the predicted path from the current pose (position and attitude). Within this range, the navigation system makes adjustments or predictions to ensure the device can smoothly travel or move along the predetermined path.

[0069] In one possible implementation, S7 includes:

[0070] S701: Sets the path variable used to control the underwater helicopter's movement along a spiral trajectory, increasing from 0 to the maximum value of the path variable.

[0071] S702: Determine the spiral radius based on the path variable:

[0072]

[0073] ω max =2πN

[0074] Among them, R iR0 represents the initial spiral radius, and ω represents the path variable. max This represents the maximum value of the path variable, and N represents the number of rotations of the spiral.

[0075] It should be noted that during the docking process, the underwater helicopter gradually approaches the base station along a variable-diameter spiral trajectory. The spiral radius gradually decreases with the path variable, forming a stable and progressive three-dimensional guidance trajectory. This effectively improves the success rate and docking stability of the underwater helicopter's autonomous docking in complex marine environments.

[0076] S703: Calculate the desired position in the horizontal direction based on the helix radius:

[0077]

[0078] Where, x k (ω),y k (ω) represents the desired position in the horizontal direction, cos represents the cosine function, sin represents the sine function, and (c x ,c y ) indicates the target location of the base station.

[0079] S704: Calculate the expected depth based on path variables:

[0080]

[0081] Among them, z d H represents the desired depth. d H represents the initial target depth. f Indicates the target depth.

[0082] S705: Calculating sailing speed based on path variables:

[0083]

[0084] Among them, U d2 U represents sailing speed. max This indicates the maximum speed.

[0085] It should be noted that the maximum sailing speed is determined empirically based on sea conditions and AUH power conditions.

[0086] S706: By comparing the desired position with the actual position of the underwater helicopter, the lateral and longitudinal errors are obtained.

[0087]

[0088] Where, x e y represents the lateral error. e Indicates longitudinal error, (x k ,yk ) represents the horizontal coordinate of the path reference point, α k Indicates the path tangent angle.

[0089] S707: The forward sight distance is calculated using the following formula, based on longitudinal error, sailing speed, and path curvature:

[0090]

[0091] Where, Δ ye Δ represents the foresight distance based on longitudinal error. max Indicates the maximum forward sight distance, Δ min Indicates the minimum forward sight distance. || represents the maximum value of the longitudinal error, and || represents the absolute value. Δ s U represents the forward-looking distance based on the sailing speed. d2 Indicates sailing speed. Δ represents the maximum speed of navigation. c K represents the forward sight distance based on path curvature. c This represents the adjustable curvature gain, where Λ represents the path curvature, and Λ = 1 / R. i .

[0092] It should be noted that the maximum and minimum forward viewing distances are determined empirically.

[0093] S708: The forward-looking distance of the underwater helicopter is dynamically adjusted by weighted fusion of longitudinal error, speed and path curvature.

[0094] In one possible implementation, the forward-looking distance of the underwater helicopter is specifically:

[0095]

[0096] Where Δ represents the forward-looking distance of the underwater helicopter. w represents the weights based on the forward look distance, which is determined by the longitudinal error. s w represents the weight of the forward-looking distance based on the sailing speed. c This represents the weight based on the forward look-ahead distance according to the path curvature.

[0097] Specifically, a method of dynamically adjusting the forward-looking distance is used to optimize the adaptive line-of-sight guidance rate algorithm in real time. This is achieved by comprehensively considering the longitudinal error y. e Speed ​​U d2The forward look-ahead distance (FTD) is dynamically adjusted based on the path curvature Λ. When the longitudinal error is large, the FTD increases to allow for early correction; at lower speeds, the FTD increases to ensure precise control during slow movements; and when the path curvature is large, the FTD also increases to address the challenges posed by the trajectory curvature. Ultimately, by weighted fusion of these factors, the FTD can be dynamically adjusted according to real-time mission requirements, thereby improving the stability of the underwater helicopter in complex environments and ensuring accurate and smooth docking along a spiral trajectory.

[0098] In this invention, by weighted fusion of longitudinal error, speed, and path curvature, this dynamic adjustment method can better cope with dynamic environments and unpredictable changes, improving the system's robustness in complex marine environments. For example, in situations with strong currents or turbulence, the system can adapt to changes in speed and path curvature, ensuring stable mission execution. Simultaneously, the dynamically adjusted forward look-ahead distance can be adjusted accordingly based on changes in path curvature. When the path is significantly curved, increasing the forward look-ahead distance ensures that the underwater helicopter can turn smoothly in complex curves, avoiding control instability due to excessive curvature changes and maintaining a stable docking process.

[0099] S8: Based on the forward-looking distance, the adaptive line-of-sight guidance law is used to guide the underwater helicopter to gradually approach the base station along a variable-diameter spiral trajectory.

[0100] In one possible implementation, S8 specifically includes:

[0101] S801: Calculate the path tangential angle based on the path variables:

[0102] α k (ω)=arctan2(x′ k (ω),y′ k (ω))

[0103]

[0104] Where, α k (ω) represents the path tangent angle, arctan represents the arctangent function, and x′ k (ω) represents the first derivative of the path with respect to the path variable in the x-direction, y′ k (ω) represents the first derivative of the path with respect to the path variable in the y-direction. This represents the partial derivative.

[0105] S802: Determine the adaptive line-of-sight guidance rate based on the forward-looking distance and path tangential angle.

[0106]

[0107] Where, ψ d2This represents the desired heading angle. This represents the drift angle of the adaptive estimation. denoted by l, which represents the additional lateral displacement introduced by the compensation term, and l represents the adaptive law gain.

[0108] S803: Uses an adaptive line-of-sight guidance law to guide the underwater helicopter to gradually approach the base station along a variable-diameter spiral trajectory.

[0109] In this invention, the adaptive line-of-sight guidance law can dynamically adjust and optimize parameters based on real-time forward-looking distance, path tangential angle, and error. Through these real-time adjustments, the underwater helicopter can more accurately track the predetermined spiral trajectory, reduce errors caused by heading deviations, and ensure smooth progress along the target trajectory.

[0110] In one possible implementation, the process after S8 includes:

[0111] If the mission time exceeds the first preset time, the underwater helicopter mission is determined to be abnormal, and the underwater helicopter is raised to the initial target depth and the descent operation is repeated.

[0112] It should be noted that those skilled in the art can set the size of the first preset time themselves, and this invention does not limit that.

[0113] In this invention, if the task execution time exceeds a set threshold, continuing execution may lead to unnecessary error accumulation or even failure to complete the task. By allowing the underwater helicopter to surface to a relatively safe depth, long-term error accumulation caused by the complexity of the underwater environment or equipment problems can be avoided, ensuring the long-term success of the mission.

[0114] S9: Determine if the relative horizontal distance is less than the first radius threshold. If so, record the current initial depth of the underwater helicopter and adjust the desired course to align with the target position.

[0115] It should be noted that those skilled in the art can set the size of the first radius threshold themselves, and this invention does not limit that.

[0116] S10: Determine if the relative horizontal distance is less than the second radius threshold. If so, instruct the underwater helicopter to perform a descent.

[0117] It should be noted that those skilled in the art can set the size of the second radius threshold themselves, and this invention does not limit that.

[0118] Specifically, when the relative horizontal distance d between the AUH and the base station is less than the radius threshold, the system enters stage three, the long-distance return stage, at which point the depth of the AUH is denoted as H. m In the horizontal direction, the desired heading ψ d3 =ψ d1AUH towards the target location (c x ,c y Approach and align. Satisfy d in AUH <R f2 Each descent is performed once, and the entire phase is divided into n descents, with the depth of each descent being (H). m -H f ) / n.

[0119] In this invention, descending in stages avoids the oscillations or instability that can occur with a single, large descent in an underwater helicopter. This gradual descent method allows the AUH to remain stable as it approaches the base station, reducing the risk of loss of control or misoperation that might result from rapid descent, thereby enhancing the stability of the entire process.

[0120] In one possible implementation, the process after S10 includes:

[0121] If the descent alignment time exceeds the second preset time, the underwater helicopter will rise to the initial depth and the alignment task will be repeated.

[0122] It should be noted that those skilled in the art can set the size of the second preset time themselves, and this invention does not limit that.

[0123] S11: Upon descent to the bottom structure of the base station, determine whether the difference between the real-time pose and the desired pose of the underwater helicopter is less than a preset difference. If yes, determine that the underwater helicopter has completed docking. Otherwise, proceed to S12.

[0124] In one possible implementation, the process after S11 includes:

[0125] The base station locking mechanism is activated, and the underwater helicopter, which has completed docking, is locked onto the base station.

[0126] In this invention, if the underwater helicopter is not locked during docking, it may drift due to external water currents or other environmental factors, causing mission interruption or delay. Activating the locking mechanism securely holds the underwater helicopter to the base station, preventing any possible slippage or drift and ensuring mission continuity and stability.

[0127] S12: Allow the underwater helicopter to rise to the surface using its own buoyancy and return to S11 until the underwater helicopter completes docking.

[0128] In one possible implementation, the process after S12 includes:

[0129] After the first preset number of adjustments, if the difference between the real-time pose and the desired pose of the underwater helicopter fails to be less than the preset difference, the underwater helicopter will be raised to the initial depth and the alignment task will be performed again.

[0130] After the underwater helicopter's attitude and altitude were adjusted a second time according to the preset parameters, it failed to successfully dock. The emergency response procedure was initiated, and the underwater helicopter jettisoned its ballast and surfaced.

[0131] It should be noted that those skilled in the art can set the size of the first preset number of times and the second preset number of times themselves, and the present invention does not limit this.

[0132] Specifically, after the underwater helicopter descends to the bottom, if the difference between its attitude and the desired attitude exceeds the allowable range, attitude adjustment is performed. The underwater helicopter rises for a few seconds and then descends again to ensure accurate docking with the base station. If the underwater helicopter still fails to dock successfully after multiple adjustments, the emergency procedure is initiated, and the underwater helicopter jettisons its ballast and rises.

[0133] In this invention, by surfacing and re-descending after multiple adjustments, or by initiating emergency procedures when a mission fails, underwater helicopters can improve the accuracy and success rate of mission execution.

[0134] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0135] (1) In this embodiment of the invention, autonomous navigation and adaptive trajectory guidance effectively address complex water currents and turbulence. Upon receiving the docking command, the underwater helicopter can automatically adjust its heading, depth, and speed according to the target location, ensuring stable navigation and reducing the impact of environmental factors. Furthermore, the system integrates longitudinal error, navigation speed, and path curvature information in real time to dynamically adjust the forward-looking distance, improving the robustness and accuracy of path tracking. During docking, the underwater helicopter gradually approaches the base station along a variable-diameter spiral trajectory, with the spiral radius gradually decreasing as the path changes, forming a stable and progressive three-dimensional guidance trajectory. This effectively improves the success rate and docking stability of the underwater helicopter's autonomous docking in complex marine environments.

[0136] (2) In this embodiment of the invention, the accuracy and stability of traditional sensor positioning are optimized by introducing an optical navigation light source. Especially in complex environments, the optical navigation mode can improve the reliability of positioning. At the same time, the system adjusts the desired course as it approaches the target to accurately align with the target position. By adjusting the attitude through buoyancy, the system can also self-correct when encountering attitude deviations, ensuring that the underwater helicopter can successfully complete the docking mission.

Claims

1. A method for underwater helicopter variable diameter screw docking based on dynamic parameter adjustment, characterized in that, include: S1: Measurement information on the deployment of the base station after it is placed on the seabed; S2: Convert the arrangement information to the navigation coordinate system of the underwater helicopter to determine the target position and target depth of the underwater helicopter entering the dock; S3: When a docking command is received, calculate the relative horizontal distance between the initial position of the underwater helicopter and the target position; S4: Determine whether the relative horizontal distance is greater than the relative horizontal distance threshold; if yes, proceed to S5; otherwise, proceed to S6. S5: Control the underwater helicopter to autonomously navigate to the target location according to the set desired speed, desired depth and desired course, and return to S4; S6: Turn on the optical navigation light source of the base station. When the underwater helicopter detects the optical navigation light source, it enters the optical navigation mode and begins spiral docking using an adaptive line-of-sight guidance law. S7: Based on the longitudinal error, speed, and path curvature of the underwater helicopter, dynamically adjust the forward sight distance of the underwater helicopter; S8: Based on the forward-looking distance, the adaptive line-of-sight guidance law is used to guide the underwater helicopter to gradually approach the base station along a variable-diameter spiral trajectory; S9: Determine whether the relative horizontal distance is less than the first radius threshold; if so, record the current initial depth of the underwater helicopter and adjust the desired course to align with the target position; S10: Determine whether the relative horizontal distance is less than the second radius threshold; if so, instruct the underwater helicopter to perform a descent operation; S11: When descending to the bottom structure of the base station, determine whether the difference between the real-time pose and the desired pose of the underwater helicopter is less than a preset difference; if so, determine that the underwater helicopter has completed docking. Otherwise, proceed to S12; S12: Cause the underwater helicopter to rise to the surface using its own buoyancy and return to S11 until the underwater helicopter completes docking.

2. The method of claim 1, wherein, The formula for calculating the relative horizontal distance is: wherein, denotes the relative horizontal distance, denotes the initial position of the underwater helicopter, denotes the target position of the base station.

3. The method of claim 2, wherein, The formula for calculating the desired course is: wherein, denotes the desired heading, denotes the arctangent function.

4. The method of claim 1, wherein, S7 includes: S701: Set the path variable used to control the underwater helicopter's movement along the spiral trajectory to increase from 0 to the maximum value of the path variable; S702: Determine the spiral radius based on the path variables: in, Indicates the helix radius. Indicates the initial spiral radius. Represents path variables. This represents the maximum value of the path variable. N Indicates the number of rotations of the spiral; S703: Based on the spiral radius, calculate the desired position in the horizontal direction: in, Indicates the desired position in the horizontal direction. Represents the cosine function. Represents the sine function. Indicates the target location of the base station; S704: Calculate the desired depth based on the path variables: in, Indicates the desired depth. Indicates the initial target depth. Indicates the target depth; S705: Calculate the sailing speed based on the path variables: in, Indicates sailing speed. Indicates the maximum speed; S706: Compare the desired position with the actual position of the underwater helicopter to obtain the lateral error and longitudinal error: in, Indicates lateral error. Indicates longitudinal error. Represents the coordinates of the path reference point Indicates the path tangential angle; S707: Calculate the forward sight distance based on the longitudinal error, the sailing speed, and the path curvature using the following formula: in, This represents the forward sight distance based on the longitudinal error. Indicates the maximum forward sight distance. Indicates the minimum forward sight distance. | represents the maximum value of the longitudinal error, and | represents the absolute value. This indicates the forward-looking distance based on the sailing speed. Indicates sailing speed. Indicates the maximum speed of navigation. This represents the forward sight distance based on path curvature. This indicates adjustable curvature gain. Indicates path curvature. ; S708: The forward-looking distance of the underwater helicopter is dynamically adjusted by weighted fusion based on the longitudinal error, the navigation speed, and the path curvature.

5. The underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment according to claim 4, characterized in that, The forward-looking distance of the underwater helicopter is specifically: in, This indicates the forward-looking distance of an underwater helicopter. This represents the weights based on the forward look-ahead distance, which is determined by the longitudinal error. This represents the weighting of the forward-looking distance based on the sailing speed. This represents the weight based on the forward look-ahead distance according to the path curvature.

6. The underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment according to claim 4, characterized in that, S8 specifically includes: S801: Calculate the path tangential angle based on the path variables: in, Indicates the path tangential angle. Represents the arctangent function. Indicates the path is in x The first derivative of the direction with respect to the path variable. Indicates the path is in y The first derivative of the direction with respect to the path variable. Represents partial derivatives; S802: Determine the adaptive line-of-sight guidance law based on the forward-looking distance and the path tangential angle: in, This represents the desired heading angle. This represents the drift angle of the adaptive estimation. This indicates the additional lateral displacement introduced by the compensation term. Indicates the adaptive law gain; S803: Using the adaptive line-of-sight guidance law, guide the underwater helicopter to gradually approach the base station along the variable-diameter spiral trajectory.

7. The underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment according to claim 4, characterized in that, Following S8, the following is also included: If the mission time exceeds the first preset time, the underwater helicopter mission is determined to be abnormal, and the underwater helicopter is raised to the initial target depth and the descent operation is repeated.

8. The underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment according to claim 1, characterized in that, Following S10, the following is also included: If the descent alignment time exceeds the second preset time, the underwater helicopter will be surfaced to the initial depth to re-execute the alignment task.

9. The underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment according to claim 1, characterized in that, Following S11, the following is also included: The base station locking structure is activated, and the underwater helicopter that has completed docking is locked onto the base station.

10. The underwater helicopter variable-diameter spiral docking method based on dynamic parameter adjustment according to claim 1, characterized in that, Following S12, the following is also included: After the first preset number of adjustments, if the difference between the real-time pose and the desired pose of the underwater helicopter fails to be less than the preset difference, the underwater helicopter will be raised to the initial depth and the alignment task will be executed again. If the underwater helicopter fails to dock after its attitude and altitude have been adjusted a second preset number of times, an emergency procedure is initiated, and the underwater helicopter jettisons its ballast and surfaces.

Images