A whole-process safety control method for underwater recovery of underwater vehicles by a mother ship

Abstract

The present invention provides a full-process safety control method for underwater recovery of an underwater vehicle by a mother ship, comprising: short-term return path planning: obtaining the position of the mother ship, adopting an A* algorithm to plan the return path, and dynamically adjusting the expected speed; position and attitude adjustment in the adjustment stage: when the underwater vehicle approaches the mother ship to a set distance, starting an optical recognition system to identify a characteristic mark of a dock entrance, calculating a relative position deviation and an attitude deviation, and making adjustments using a propeller and a rudder; real-time attitude adjustment in the docking stage: obtaining a current speed deviation and an attitude deviation, and adopting a fuzzy control algorithm to generate control parameters of the propeller and the rudder; full-process safety monitoring and emergency processing: real-time monitoring of the position, attitude and power information of the underwater vehicle, and when it is monitored that at least one of the position deviation, attitude error or power exceeds a corresponding threshold, performing at least one of the following emergency operations: replanning the path; starting a backup power system.

Description

Technical Field

[0001] The present invention belongs to the technical field of automatic control of underwater vehicle recovery, and in particular relates to a whole-process safety control method for underwater recovery of an underwater vehicle by a mother ship. Background Art

[0002] With the continuous advancement of ocean development and scientific research, underwater vehicles (UUVs) are playing an increasingly important role in marine environmental monitoring, resource exploration, military reconnaissance, and other fields. After completing their missions, UUVs need to be safely and efficiently recovered to their motherships for subsequent maintenance, data processing, and redeployment. However, recovering UUVs from their motherships is a complex and challenging process involving multiple steps and technologies, and many challenges remain.

[0003] From the perspective of the marine environment, it is complex and ever-changing. Factors such as ocean currents, waves, and tides can significantly impact the recovery of underwater vehicles. The speed and direction of ocean currents are constantly changing, which may cause the underwater vehicle to deviate from the planned recovery path, increasing the difficulty and risk of recovery. The ups and downs of the waves can cause the mother ship to sway, affecting the stability of the dock and the docking accuracy of the underwater vehicle. The rise and fall of the tides can change the depth and pressure of the seawater, affecting the buoyancy and posture of the underwater vehicle. In addition, organisms and debris in the ocean may also interfere with the recovery process of the underwater vehicle. For example, seaweed may entangle the propellers of the underwater vehicle, affecting its normal operation.

[0004] Current technologies for the navigation and positioning of underwater vehicles (AUVs) still have certain limitations. The underwater environment significantly attenuates the propagation of electromagnetic waves, making traditional radio navigation difficult to effectively apply underwater. While acoustic navigation technology is widely used underwater, acoustic signals are susceptible to interference from factors such as ocean noise and multipath effects, resulting in low positioning accuracy. Furthermore, when approaching a mother ship, an AUV requires real-time access to the precise position and attitude of the mother ship and dock for path planning and attitude adjustments. However, the accuracy and real-time performance of existing positioning technologies at close ranges do not yet meet the requirements for safe recovery of AUVs.

[0005] In terms of the control of the recovery process, there is currently a lack of a complete and effective full-process safety control method and system. From the return to the docking process, the underwater vehicle needs to go through multiple stages, and each stage has different tasks and requirements. For example, in the near stage of the return, the underwater vehicle needs to plan its own path according to the position of the mother ship and continue to approach the mother ship; in the adjustment stage, it needs to identify the location of the dock entrance and adjust its position and attitude; in the docking stage, it needs to continuously adjust its own attitude according to the surrounding ocean current conditions and its own dynamic characteristics to avoid collisions. However, existing control methods often only focus on the problems of a certain stage, lacking overall consideration and coordinated control of the entire recovery process, which can easily lead to errors and accidents during the recovery process.

[0006] Furthermore, current recovery systems lack reliability and safety. Recovery system hardware is susceptible to corrosion and damage from the marine environment, leading to system failures. Furthermore, the recovery process is not highly automated, requiring extensive manual intervention, increasing operator workload and the risk of human error. If an unexpected situation arises during the recovery process, the existing recovery system may be unable to respond promptly and effectively, compromising the safe recovery of the underwater vehicle. Summary of the Invention

[0007] In response to the defects and shortcomings of the existing technology, the present invention provides a method and system for controlling the entire process of underwater recovery of an underwater vehicle by a mother ship. The core innovative design is as follows:

[0008] Multi-stage collaborative control architecture: The recovery process is divided into three stages: the return phase, the adjustment phase, and the docking phase. Through seamless switching of differentiated technologies such as acoustic positioning (long-range navigation), optical recognition (short-range precise positioning), and fuzzy control (anti-disturbance attitude adjustment), coordinated control of the entire process from path planning to precise docking is achieved, solving the problem of lack of coordination in existing technologies.

[0009] Marine environment adaptive mechanism:

[0010] Dynamic integration of ocean current speeds during the return leg to correct the expected speed in real time and quantify the cumulative impact of ocean currents on the path (through joint optimization of path length and the cumulative effect of ocean currents in the time domain);

[0011] During the docking phase, anti-disturbance control parameters are generated based on fuzzy rule reasoning of ocean current deviation and attitude deviation to improve robustness in complex sea conditions.

[0012] Multi-source perception and security closed loop:

[0013] The fusion of acoustic and optical positioning overcomes the lack of accuracy of single positioning technology;

[0014] The quaternion attitude error threshold determination is combined with adaptive modulation coding transmission to build a full-process safety monitoring system of anomaly detection-replanning-backup power linkage, significantly improving recovery reliability.

[0015] The solutions adopted by the present invention to solve the technical problems specifically include:

[0016] A method for controlling the entire process of underwater recovery of an underwater vehicle by a mother ship comprises:

[0017] Return route planning: The mother ship's position is obtained through the acoustic positioning system, the A* algorithm is used to plan the return route, and the desired speed is dynamically adjusted according to the real-time monitored ocean current speed;

[0018] Adjustment section position and attitude adjustment: When the underwater vehicle approaches the mother ship to a set distance, the optical recognition system is activated to identify the characteristic mark of the dock entrance, calculate the relative position deviation and attitude deviation, and use the thrusters and rudders to make adjustments;

[0019] Real-time attitude adjustment during docking: ocean current sensors and inertial measurement units are used to obtain current velocity deviation and attitude deviation, and fuzzy control algorithms are used to generate control parameters for the thrusters and rudders.

[0020] Full-process safety monitoring and emergency response: Real-time monitoring of the underwater vehicle's position, attitude, and battery information. When at least one of the position deviation, attitude error, or battery level exceeds the corresponding threshold, at least one of the following emergency operations is performed:

[0021] Replan the path, where the cost function of the path includes the cumulative cost of the path length and the influence of ocean currents;

[0022] Start the backup power system.

[0023] Furthermore, the acoustic positioning system is implemented in the following manner:

[0024] The underwater vehicle receives the acoustic signal transmitted by the mother ship's acoustic beacon and calculates the distance to the mother ship by measuring the propagation time of the acoustic signal;

[0025] The position of the underwater vehicle relative to the mother ship is determined using the principle of trilateral positioning by combining the information of acoustic beacons at at least three different locations.

[0026] Furthermore, the optical recognition system includes:

[0027] Adopting adaptive image enhancement algorithm to process underwater images;

[0028] The characteristic mark of the dock entrance is identified based on the HSV color space and shape features.

[0029] Furthermore, the fuzzy control algorithm includes:

[0030] The current velocity deviation and attitude deviation are used as input variables for fuzzy processing;

[0031] Generate control parameters based on the preset fuzzy control rules;

[0032] The precise control parameters of the thruster and rudder are obtained through defuzzification processing.

[0033] Furthermore, the position deviation is obtained by calculating the deviation between the current posture and the predetermined path, and when the deviation modulus exceeds the position deviation threshold, it is determined to be abnormal;

[0034] The posture error is determined to be abnormal by comparing the modulus of the posture error quaternion with a posture error threshold.

[0035] Furthermore, the cost function of the re-planning path includes:

[0036] The basic path cost including the path length;

[0037] Current accumulation cost: includes the time-domain accumulation of the impact of the current on the path, which is achieved by integrating or discretely summing the modulus of the current velocity vector in the time dimension;

[0038] Joint optimization: The basic path cost is linearly combined with the current cumulative cost, and the weight coefficient is dynamically adjusted according to the current intensity.

[0039] Furthermore, the security monitoring information transmission adopts adaptive modulation and coding technology, and dynamically adjusts the modulation mode and coding rate according to the channel signal-to-noise ratio.

[0040] Furthermore, during the real-time adjustment of the attitude during the docking phase, the attitude of the underwater vehicle is updated through the Newton-Euler equation according to the control parameters output by the fuzzy control algorithm.

[0041] And, a full-process safety control system for underwater recovery of underwater vehicles by a mother ship, comprising:

[0042] Return route planning module: used to obtain the mother ship's position through the acoustic positioning system, plan the return route based on the A* algorithm, and dynamically adjust the desired speed according to the real-time ocean current speed;

[0043] Adjustment section position and attitude adjustment module: used to activate the optical recognition system to identify the dock feature mark when approaching the mother ship at a set distance, calculate the relative position and attitude deviation, and control the thruster and rudder adjustment;

[0044] Real-time attitude adjustment module during docking: used to obtain current velocity deviation and attitude deviation through current sensors and IMU, and generate thruster and rudder control parameters using fuzzy control algorithm;

[0045] Safety monitoring and emergency response module: used to monitor location, posture, and power information in real time. When the abnormality exceeds the threshold, it triggers path replanning or backup power system.

[0046] The cost function of the path replanning includes the path length and the time domain accumulation of the ocean current influence.

[0047] Furthermore, the safety monitoring and emergency handling module includes:

[0048] Adaptive modulation and coding unit, dynamically adjusts the modulation mode and coding rate according to the channel signal-to-noise ratio;

[0049] The quaternion attitude analysis unit determines abnormalities by calculating the quaternion modulus length of the attitude error.

[0050] And, an electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the program.

[0051] A non-transitory computer-readable storage medium stores a computer program, which implements the steps of the above method when executed by a processor.

[0052] Compared with the prior art, the present invention and its preferred embodiments have at least the following beneficial effects:

[0053] Improved coordinated control capabilities throughout the entire process: Through a multi-stage collaborative control architecture encompassing the return phase, adjustment phase, and docking phase, combined with a closed-loop differentiated technology chain of acoustic positioning, optical recognition, and fuzzy control, the problem of fragmented recovery processes in existing technologies is resolved, enabling efficient connection from path planning to precise docking, significantly improving the smoothness and reliability of the recovery process.

[0054] Enhanced adaptability to complex marine environments:

[0055] The return leg dynamically integrates the ocean current velocity to correct the speed in real time and quantify the cumulative impact of the ocean current on the route, effectively suppressing the route deviation caused by ocean current interference;

[0056] During the docking phase, anti-disturbance control parameters are generated based on fuzzy rule reasoning of ocean current deviation and attitude deviation to improve attitude stability in strong disturbance environments.

[0057] Security and robustness optimization:

[0058] The fusion and complementarity of acoustic and optical positioning overcomes the limitations of a single technology and improves the accuracy of long-range and short-range navigation and positioning;

[0059] The quaternion attitude abnormality threshold judgment combined with adaptive communication guarantee builds a safety closed loop of real-time monitoring-dynamic replanning-emergency power linkage, greatly reducing the risk of collision and loss of control.

[0060] Synergy Gains:

[0061] Adaptive image enhancement in optical recognition improves feature capture capabilities and ensures close-range docking accuracy;

[0062] Path replanning introduces the ocean current time-domain cumulative cost factor to optimize the balance between path efficiency and safety under complex sea conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0064] Figure 1 This is a schematic diagram of a specific implementation module of the system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] In order to make the features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description:

[0066] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this application belongs.

[0067] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0068] The present invention provides a full-process safety control method for underwater vehicle recovery by a mother ship. This method addresses existing issues such as significant impact on the marine environment, low navigation and positioning accuracy, lack of full-process control, and insufficient reliability and safety during underwater vehicle recovery by a mother ship. The method achieves safe and efficient recovery of the underwater vehicle from return to docking. The core technical solution includes: During the near-return phase, the underwater vehicle obtains the mother ship's position through an acoustic positioning system, plans a return path based on an A* algorithm, and makes real-time adjustments based on marine environmental information; during the adjustment phase, an optical recognition system is activated to identify the dock entrance feature, calculate relative position and attitude deviations, and adjust the position using thrusters and rudders; during the docking phase, information is obtained from current sensors and an inertial measurement unit, and a fuzzy control algorithm is used to adjust the thrusters and rudders. Ultrasonic ranging sensors are also used to prevent collisions. A full-process safety monitoring system is also established to monitor and handle abnormal situations in real time. The present invention offers advantages such as improved recovery safety, enhanced navigation and positioning accuracy, coordinated control throughout the entire process, and adaptability to complex marine environments.

[0069] The implementation of its core technical solution includes the following steps:

[0070] Return route planning: The underwater vehicle obtains the mother ship's position information through the acoustic positioning system, plans the return route using a path planning method based on the A* algorithm, and adjusts the route based on real-time monitoring of the ocean environment;

[0071] Adjustment section position and attitude adjustment: When the underwater vehicle approaches the mother ship at a certain distance, it activates the optical recognition system to identify the characteristic mark of the dock entrance, calculates the relative position and attitude deviation, and uses the thrusters and rudders to adjust the position and attitude;

[0072] Real-time attitude adjustment during docking: The underwater vehicle monitors ocean currents and its own dynamic characteristics in real time during docking, using a fuzzy control algorithm to adjust its thrusters and rudders. Meanwhile, an ultrasonic ranging sensor at the dock entrance monitors the distance to the dock's inner wall, and takes action when the distance falls below a safety threshold.

[0073] Full-process safety monitoring and emergency response: Establish a safety monitoring system to monitor the status of underwater vehicles, marine environment and dock status information in real time, and initiate emergency response procedures when abnormal situations are detected.

[0074] Among them, the acoustic positioning system obtains the mother ship's position information in the following way: the underwater vehicle is equipped with an acoustic receiver, the mother ship is installed with an acoustic beacon, the acoustic beacon periodically emits acoustic signals, the underwater vehicle determines the distance from the mother ship by measuring the propagation time of the acoustic signal, and uses the trilateral positioning principle combined with multiple acoustic beacon information to determine the relative position.

[0075] The implementation of path planning based on the A* algorithm is as follows: abstract the ocean environment into a grid map, define the starting point and end point, calculate the g(n), h(n), and f(n) values ​​of the nodes by maintaining the open list and the closed list, and select the node with the smallest f(n) value to expand until the end point is found or the open list is empty.

[0076] When the optical recognition system identifies the characteristic markings of the dock entrance, it uses an adaptive image enhancement algorithm to improve image quality, and adopts a joint recognition algorithm based on color space and shape features to identify the characteristic markings.

[0077] When the fuzzy control algorithm is used in the docking stage, the input of the fuzzy controller is determined to be the current speed deviation and attitude deviation, and the output is the control parameters of the thruster and rudder. The input and output variables are fuzzified, and fuzzy control rules are formulated. The precise control parameters are obtained through reasoning synthesis and defuzzification.

[0078] During the whole process of safety monitoring and emergency response, information is collected through various sensors and transmitted using adaptive modulation and coding technology. The data analysis module determines whether there is an abnormality by calculating position deviation, attitude error, power level, etc. and comparing them with the corresponding thresholds. The emergency response procedures include issuing alarms, adjusting operating parameters, and starting the backup power system.

[0079] Based on the above method, an embodiment of the present invention further provides a full-process safety control system for underwater recovery of an underwater vehicle by a mother ship, comprising:

[0080] Return route planning module: used to obtain the mother ship's position information through the acoustic positioning system, plan the return route based on the A* algorithm, and adjust the route in real time according to the ocean environment information;

[0081] Adjustment section position and attitude adjustment module: used to activate the optical recognition system to identify the dock entrance feature mark after the underwater vehicle approaches the mother ship at a certain distance, calculate the relative position and attitude deviation, and control the thrusters and rudders for adjustment;

[0082] Real-time attitude adjustment module during docking: used to monitor ocean currents and its own dynamic characteristics in real time, use fuzzy control algorithms to adjust thrusters and rudders, and use ultrasonic ranging sensors to monitor the distance to the inner wall of the dock and take appropriate measures;

[0083] Full-process safety monitoring and emergency response module: used to establish a safety monitoring system, monitor relevant information in real time, and initiate emergency response procedures when an abnormality occurs.

[0084] The following is a more detailed introduction to the embodiments of the present invention:

[0085] 1. Return route planning

[0086] 1.1 Acoustic positioning to obtain the mother ship's position

[0087] In a complex ocean environment, traditional radio navigation technology is difficult to apply effectively due to the strong attenuation characteristics of underwater electromagnetic wave propagation. Therefore, an acoustic positioning system is used to obtain the position of the mother ship. The underwater vehicle is equipped with an acoustic receiver and the mother ship is equipped with an acoustic beacon. The acoustic beacon periodically transmits an acoustic signal, and the underwater vehicle determines the distance from the mother ship by measuring the propagation time of the acoustic signal. Let the time when the underwater vehicle receives the acoustic signal be , the propagation speed of acoustic signals in seawater is , then the distance between the underwater vehicle and the mother ship is It can be expressed as:

[0088] Assuming that the underwater vehicle receives signals from multiple acoustic beacons of the mother ship at the same time, the position of the underwater vehicle relative to the mother ship can be determined by using the principle of trilateral positioning and combining the information of acoustic beacons at at least three different locations. Let the coordinates of the jth acoustic beacon be , the coordinates of the underwater vehicle are , then:

[0089] By solving the above equations, the coordinates of the underwater vehicle can be obtained , and then determine its relative position with the mother ship.

[0090] 1.2 Initial path planning based on A* algorithm

[0091] The A* algorithm is a heuristic search algorithm used to find the shortest path in a graph. In the specific application of this embodiment, the ocean environment is abstracted into a two-dimensional or three-dimensional grid map, and each grid represents a feasible location. Let the current position of the underwater vehicle be the starting point , the mother ship's position is the end point .

[0092] The A* algorithm works by maintaining two lists: the open list and close list The open list contains nodes to be explored, and the closed list contains nodes that have been explored. For each node , define two cost functions:

[0093] :From the starting point To Node the actual cost.

[0094] : Slave node To the end The estimated cost is calculated using heuristic functions such as Manhattan distance or Euclidean distance.

[0095] :From the starting point Passing the node To the end The total estimated cost.

[0096] The algorithm steps are as follows:

[0097] The starting point Join the open list .

[0098] When the open list When not empty:

[0099] From the open list Select The node with the smallest value .

[0100] if It's the end , then the path planning is completed and the path is backtracked.

[0101] The node From the open list Remove and add to the closed list .

[0102] Traversing nodes All adjacent nodes :

[0103] if In the closed list In, ignore.

[0104] Calculate from the starting point Passing the node To Node The new price ,in It is a slave node To Node the price.

[0105] if Not in open list Add it to the open list , and set , Using heuristic function calculation, .

[0106] if Already in open list In, and ,renew , .

[0107] 1.3 Real-time route adjustment considering the ocean environment

[0108] The ocean environment is complex and changeable. Factors such as ocean currents, water temperature, and salinity can affect the navigation of underwater vehicles. Ocean currents can cause underwater vehicles to deviate from their intended paths, so the impact of ocean currents needs to be considered in real time. Assume that the ocean current speed is , the expected speed of the underwater vehicle is , then the actual speed of the underwater vehicle for:

[0109] In order to make the underwater vehicle sail along the planned path, it is necessary to adjust the desired speed according to the ocean current conditions. . Assume the current position of the underwater vehicle is , the next target location on the path is , then the expected speed It can be calculated according to the following formula:

[0110] in, Is the underwater vehicle from the position To location During the voyage, the ocean current information is constantly monitored and the expected speed is adjusted in real time. To ensure that the underwater vehicle can accurately and quickly approach the mother ship. At the same time, combined with other ocean environmental information, such as the impact of water temperature and salinity on the propagation speed of acoustic signals, the acoustic positioning results are corrected to improve the accuracy of path planning.

[0111] 2. Adjust the position and posture of the adjustment segment

[0112] 2.1 Optical Recognition System Startup and Feature Marker Search

[0113] When the underwater vehicle approaches the mother ship to a certain distance (e.g. 50 meters), the optical recognition system is activated. This system mainly consists of a camera installed at the front of the underwater vehicle. In a complex underwater environment, factors such as poor lighting conditions and water scattering can seriously affect the quality of the image. In order to improve the recognition rate of feature identification, an adaptive image enhancement algorithm is used. Suppose the original image is , the image after image enhancement is , the adaptive image enhancement algorithm can be expressed as:

[0114] in, is the transformation function, It is a parameter related to the local features of the image and is obtained by analyzing the brightness, contrast and other characteristics of the local area of ​​the image.

[0115] The camera starts to search for the characteristic marks of the dock entrance in a certain scanning mode. These characteristic marks are usually marks of specific colors, unique shapes, etc. In order to accurately identify these features, a joint recognition algorithm based on color space and shape features is adopted. First, the image is converted from RGB color space to HSV color space. 、 、 They are hue, saturation and brightness components respectively. For the characteristic identification of a specific color, by setting 、 、 The threshold range is used to preliminarily screen out possible areas.

[0116] 2.2 Calculation of relative position and attitude deviation

[0117] After identifying the feature markers, the image processing module further analyzes the image. Assume that the position of the underwater vehicle in the image coordinate system is , the position of the dock entrance feature marker in the image coordinate system is , then the relative position deviation on the image plane is:

[0118] In order to convert the relative position deviation on the image plane into the relative position deviation in the real space, camera calibration is required. Assume that the intrinsic parameter matrix of the camera is , the external parameter matrix is ,in is the rotation matrix, is the translation vector. According to the camera imaging model, the relative position deviation in the actual space It can be calculated by the following formula:

[0119] By solving the above equations, we can get .

[0120] For the calculation of posture deviation, a method based on feature point matching and rotation matrix decomposition is used. Feature points of feature identification are extracted from the image, and their corresponding points in different image frames are found through feature point matching algorithm. Assume that the coordinates of the feature points in the initial posture are , the coordinates of the feature points in the current posture are , then by calculating the rotation matrix To represent the posture change. Rotation matrix Can be decomposed into 、 、 Axis rotation angle ,Right now:

[0121] in, 、 、 Respectively around 、 、 Axis rotation 、 、 Angle rotation matrix. By rotating the matrix Decomposition can be performed to obtain the posture deviation .

[0122] 2.3 Position and attitude adjustment control

[0123] The control module sends control instructions to the thrusters and rudders based on the calculated relative position and attitude deviation. Assume that the thrust of the thruster is , the deflection angle of the rudder surface is , the control law can adopt PID control algorithm. For position deviation , the thrust control law of the propeller is:

[0124] in, 、 、 are the proportional, integral, and differential coefficients respectively.

[0125] For posture deviation , the control law of the deflection angle of the rudder surface is:

[0126] in, 、 、 are the proportional, integral and differential coefficients of attitude control respectively.

[0127] By continuously adjusting the thrust of the propellers and the deflection angle of the rudders, the axis of the underwater vehicle is aligned with the axis of the dock entrance as closely as possible. During the adjustment process, the above identification, calculation, and control steps are repeated until the position and attitude of the underwater vehicle meet the docking requirements.

[0128] 3. Real-time adjustment of attitude during docking

[0129] During the docking phase, when an underwater vehicle is recovered underwater by a mother ship, it faces a complex marine environment and stringent attitude control requirements. During this phase, the underwater vehicle's attitude must be adjusted in real time to ensure safe and accurate entry into the dock and avoid collisions with the dock walls. The following details the technical details of real-time attitude adjustment during docking.

[0130] 3.1 Acquisition of ocean current and attitude information

[0131] The underwater vehicle is equipped with current sensors and inertial measurement units (IMUs) to obtain real-time information about the surrounding ocean currents and its own posture. The current sensors can measure the speed of the ocean currents. and direction ,in is a two-dimensional vector, , respectively, indicating that the ocean current and The velocity component in the direction; It represents the angle between the ocean current direction and the reference coordinate axis.

[0132] The IMU can provide the attitude information of the underwater vehicle, including the roll angle , pitch angle and yaw angle These attitude angles describe the rotation state of the underwater vehicle relative to the reference coordinate system and are an important basis for attitude adjustment.

[0133] 3.2 Fuzzy control algorithm design

[0134] To adjust the propellers and rudders of an underwater vehicle in real time based on current and attitude information, a fuzzy control algorithm is employed. Fuzzy control algorithms have the advantages of not relying on precise mathematical models and being highly robust to changes in system parameters, making them suitable for complex underwater environments.

[0135] First, determine the input and output variables of the fuzzy controller. The input variable is the ocean current velocity deviation , posture deviation (include 、 、 ), the output variable is the control parameter of the thruster and control parameters of the rudder .

[0136] Fuzzy processing is performed on the input and output variables, dividing them into different fuzzy sets and determining the membership function of each fuzzy set. , can be divided into fuzzy sets such as "Negative Big (NB)", "Negative Middle (NM)", "Negative Small (NS)", "Zero (ZO)", "Positive Small (PS)", "Positive Middle (PM)", and "Positive Big (PB)", and its membership function can adopt triangular or trapezoidal membership function.

[0137] According to the expert experience and experimental data, fuzzy control rules are formulated. Fuzzy control rules usually adopt the form of "IF-THEN", for example: "IF is NB and is PS THEN is PB and is NS".

[0138] The fuzzy control rules are inferred and synthesized to obtain the fuzzy output. Finally, the fuzzy output is converted into accurate control parameters through defuzzification. and Commonly used defuzzification methods include the centroid method and the maximum membership method.

[0139] 3.3 Posture Adjustment Model Establishment

[0140] The attitude adjustment of underwater vehicles can be modeled by the Newton-Euler equation. Assuming that the underwater vehicle is a rigid body, its dynamic equation can be expressed as:

[0141]

[0142] in, is the inertia matrix, including the mass and inertia tensor of the underwater vehicle; is the velocity vector, , is the linear velocity of the center of mass, is the angular velocity; is the time derivative of the velocity vector v, representing acceleration; is the Coriolis- centripetal force matrix; is the damping matrix; are the gravity and buoyancy force vectors; is the control input vector, which includes the forces and moments produced by the thrusters and control surfaces.

[0143] In the process of posture adjustment, the control parameters obtained by the fuzzy control algorithm are and , calculate the control input vector Then, by solving the above dynamic equations, we can get the acceleration of the underwater vehicle: , and then update the speed and attitude information of the underwater vehicle.

[0144] 3.4 Collision Warning and Handling

[0145] An ultrasonic ranging sensor is installed at the dock entrance to monitor the distance between the underwater vehicle and the inner wall of the dock in real time. When the distance Less than the safety threshold When an error occurs, the system issues an alarm and takes appropriate measures.

[0146] Collision warning can be based on a threshold method, that is, when When the vehicle is detected as likely to collide, the propeller power and the rudder angle can be adjusted to keep the underwater vehicle away from the dock wall. For example, reduce the propeller power. , and adjust the control parameters of the rudder at the same time , so that the underwater vehicle changes its course.

[0147] Through the above technical means, the real-time adjustment of the underwater vehicle's posture during the docking phase is achieved, ensuring that the underwater vehicle enters the dock safely and accurately in complex marine environments.

[0148] 4. Full process safety monitoring and emergency response

[0149] 4.1 Information Collection and Transmission

[0150] The whole process safety monitoring system needs to collect the status information of underwater vehicles, ocean environment information and dock status information in real time. The status information of underwater vehicles includes location ,attitude ,speed , power etc. Ocean environment information includes ocean current speed , ocean current direction , water temperature ,salinity etc. The dock status information includes the dock position , dock attitude wait.

[0151] This information is collected by various sensors distributed on underwater vehicles, marine environment monitoring equipment and docks. The collected information is transmitted to the monitoring center through wired or wireless communication links. In order to ensure the reliability and real-time performance of information transmission, adaptive modulation and coding technology is used to adjust the signal-to-noise ratio of the channel. Dynamically adjust the modulation mode and coding rate. Assume that the initial modulation mode is , the coding rate is ,when When changes occur, adjust according to the following rules:

[0152] in and It is a function determined by channel characteristics and communication protocol.

[0153] 4.2 Data Analysis and Anomaly Judgment

[0154] The data analysis module of the monitoring center analyzes the collected information to determine whether there are any abnormalities. For the position information of the underwater vehicle, the deviation from the planned path is calculated. To determine whether it deviates. Let the expected position on the predetermined path be ,but:

[0155] when ( is the position deviation threshold), the position is judged to be abnormal.

[0156] For posture information, by calculating the posture error To determine whether it is abnormal. Use quaternion to represent the posture, and set the expected posture to be , the current posture is , then the attitude error quaternion is:

[0157] when ( is the posture error threshold), the posture is judged to be abnormal.

[0158] For power information, when ( When is the battery threshold, it is determined that the battery is too low.

[0159] For the ocean environment information and dock status information, corresponding thresholds are also set for abnormal judgment.

[0160] 4.3 Emergency procedures

[0161] If an abnormal situation is found, the emergency processing module automatically starts the emergency processing procedure.

[0162] 4.3.1 Issuing an Alarm When an abnormal situation is detected, the system will immediately issue an alarm through the sound and light alarm device, and send an alarm message to the operator's terminal device. The alarm message includes the type of abnormality, the time and location of the abnormality, etc.

[0163] 4.3.2 Adjusting the operating parameters According to the abnormality type, adjust the operating parameters of the underwater vehicle. For example, when the position deviates, re-plan the path. Set the new target position to , using the improved A* algorithm for path planning, taking into account the impact of ocean environmental factors on the path. Path cost function Defined as:

[0164] in is the path length, and is the weight coefficient, Represents the cumulative cost of being affected by ocean currents along the path.

[0165] When the attitude is abnormal, adjust the control parameters of the thrusters and rudders, and use the feedback control algorithm to restore the attitude to normal. Assume that the attitude error is , control input for:

[0166] in and are the proportional and differential control coefficients respectively.

[0167] 4.3.3 Activate the backup power system When the battery is too low, activate the backup power system. The backup power system can be a battery pack or other energy device to ensure that the underwater vehicle can continue to complete the recovery mission or float safely waiting for rescue.

[0168] Through the above-mentioned full-process safety monitoring and emergency response methods, various abnormal situations during the recovery of underwater vehicles can be effectively dealt with, and the safety and reliability of recovery can be improved.

[0169] From the above specific design of this embodiment, it can be seen that the solution of the present invention has the following significant advantages, including:

[0170] Improved recovery safety: A full-process safety monitoring and emergency response system collects real-time information on the underwater vehicle's status, the ocean environment, and the docking bay. The data analysis module identifies any abnormalities. If an anomaly is detected, the emergency response module automatically initiates emergency procedures, such as sounding an alarm, adjusting operating parameters, and activating the backup power system. This effectively reduces the risk of collisions, damage, and other accidents during the recovery process, improving recovery safety.

[0171] Enhanced Navigation and Positioning Accuracy: An acoustic positioning system is used to determine the mother ship's position, and the underwater vehicle's relative position is determined using the principle of trilateration. Once the vehicle approaches the mother ship at a certain distance, the optical recognition system is activated to identify the dock entrance's signature. Relative position and attitude deviations are calculated using camera calibration, feature point matching, and rotation matrix decomposition. The combination of acoustic positioning and optical recognition systems compensates for the shortcomings of a single positioning technology, improving navigation and positioning accuracy and ensuring the underwater vehicle accurately approaches and enters the dock.

[0172] Achieve coordinated control throughout the entire process: The entire process of the underwater vehicle, from return to docking, is comprehensively considered, with different control strategies adopted at different stages. During the near-return phase, the A* algorithm is used to plan the path and make real-time adjustments based on the ocean environment. During the adjustment phase, an optical recognition system and PID control algorithms are used to adjust the position and attitude. During the docking phase, fuzzy control algorithms and Newton-Euler equations are used to adjust the attitude. The close coordination of these stages ensures a more efficient and smooth recovery process.

[0173] Adapt to complex ocean environments: Take full account of ocean environmental factors during path planning and attitude adjustment. For example, when planning the return route, the speed of the ocean current should be considered. Adjust desired speed , the formula is , Acoustic positioning results are corrected based on factors such as water temperature and salinity. During docking, current sensors and an IMU are used to obtain current and attitude information, and a fuzzy control algorithm is used to adjust the thrusters and rudders. These measures enable the system to adjust the underwater vehicle's operating parameters in real time based on changes in the ocean environment, improving its adaptability to complex marine environments.

[0174] Based on the above method design, the module architecture and data interaction process of the system provided by the embodiment of the present invention can be obtained as follows: Figure 1 As shown in the figure, the system mainly includes the near-return path planning module (A), the adjustment phase optical recognition module (G), the docking phase current detection module (K), and the full-process safety monitoring center (O). The near-return path planning module (A) obtains the mother ship's position data through the acoustic positioning module (B). Combined with the coordinate information from the multi-beacon fusion positioning module (D), the A* algorithm core module (E) generates an initial path. The dynamic path adjustment module (C) corrects the path in real time based on the current environment. Ultimately, the propulsion control module (F) executes the navigation instructions. The adjustment phase captures the docking compartment's signature through the optical recognition module (G). After the signature extraction module (H) calculates the coordinate deviation, the attitude solution module (I) generates control instructions to drive the rudder adjustment module (J) to complete attitude calibration. The docking phase uses the current detection module (K) to collect flow velocity and real-time attitude data. The fuzzy control decision module (L) combines feedback from the dynamic model module (M) to generate control parameters. The thruster coordination module (N) achieves precise attitude adjustment. The safety monitoring center (O) integrates the abnormal diagnosis module (P) to analyze the system status in real time, trigger the sound and light alarm device (R) and coordinate the power switching module (Q) and the emergency propulsion system (S) to handle abnormal working conditions. Each module realizes full process coordination through stage switching signals and data streams, in which the closed-loop control between path planning, attitude adjustment and dynamic model is achieved through formula and Realize dynamic coupling to ensure the safe and efficient operation of the system in complex marine environments.

[0175] Based on the same inventive concept, the present invention also provides a computer device, which includes: one or more processors and a memory for storing one or more computer programs; the program includes program instructions, and the processor is used to execute the program instructions stored in the memory. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is used to implement one or more instructions, specifically for loading and executing one or more instructions in a computer storage medium to implement the above method.

[0176] It should be further explained that, based on the same inventive concept, the present invention also provides a computer storage medium having a computer program stored thereon, which, when executed by a processor, performs the above-described method. The storage medium may be any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more conductors, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0177] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0178] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

[0179] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive various other forms of a full-process safety control method for underwater recovery of underwater vehicles by a mother ship under the inspiration of the present invention. All equal changes and modifications made within the scope of application of the present invention should be covered by the scope of the present invention.

Claims

1. A method for controlling the safety of an underwater vehicle during the entire process of underwater recovery by a mother ship, characterized in that: include: Return route planning: Get the mother ship's position through the acoustic positioning system, and use A * The algorithm plans the return route and dynamically adjusts the desired speed based on the real-time monitored ocean current speed; Adjustment section position and attitude adjustment: When the underwater vehicle approaches the mother ship to a set distance, the optical recognition system is activated to identify the characteristic mark of the dock entrance, calculate the relative position deviation and attitude deviation, and use the thrusters and rudders to make adjustments; Real-time attitude adjustment during docking: ocean current sensors and inertial measurement units are used to obtain current velocity deviation and attitude deviation, and fuzzy control algorithms are used to generate control parameters for the thrusters and rudders. Full-process safety monitoring and emergency response: Real-time monitoring of the underwater vehicle's position, attitude, and battery information. When at least one of the position deviation, attitude error, or battery level exceeds the corresponding threshold, at least one of the following emergency operations is performed: Replan the path, where the cost function of the path includes the cumulative cost of the path length and the influence of ocean currents; Start the backup power system; The position deviation is obtained by calculating the deviation between the current posture and the predetermined path, and when the deviation modulus exceeds the position deviation threshold, it is determined to be abnormal; The posture error is determined to be abnormal by comparing the modulus of the posture error quaternion with a posture error threshold; The cost function of the re-planning path includes: The basic path cost including the path length; Current accumulation cost: includes the time-domain accumulation of the impact of the current on the path, which is achieved by integrating or discretely summing the modulus of the current velocity vector in the time dimension; Joint optimization: The basic path cost is linearly combined with the current cumulative cost, and the weight coefficient is dynamically adjusted according to the current intensity.

2. The method for controlling the safety of an underwater vehicle during the entire process of underwater recovery by a mother ship according to claim 1, characterized in that: The acoustic positioning system is implemented in the following ways: The underwater vehicle receives the acoustic signal transmitted by the mother ship's acoustic beacon and calculates the distance to the mother ship by measuring the propagation time of the acoustic signal; The position of the underwater vehicle relative to the mother ship is determined using the principle of trilateral positioning by combining the information of acoustic beacons at at least three different locations.

3. The whole process safety control method for underwater recovery of an underwater vehicle by a mother ship according to claim 1 is characterized in that: The optical recognition system comprises: Adopting adaptive image enhancement algorithm to process underwater images; The characteristic mark of the dock entrance is identified based on the HSV color space and shape features.

4. The method for controlling the safety of an underwater vehicle during the entire process of underwater recovery by a mother ship according to claim 1, characterized in that: The fuzzy control algorithm includes: The current velocity deviation and attitude deviation are used as input variables for fuzzy processing; Generate control parameters based on the preset fuzzy control rules; The precise control parameters of the thruster and rudder are obtained through defuzzification processing.

5. The method for controlling the safety of an underwater vehicle during the entire process of underwater recovery by a mother ship according to claim 1, characterized in that: The information transmission of the security monitoring adopts adaptive modulation and coding technology, and dynamically adjusts the modulation mode and coding rate according to the channel signal-to-noise ratio.

6. The method for controlling the entire process of underwater vehicle recovery by a mother ship according to claim 1, characterized in that: During the real-time attitude adjustment in the docking phase, the attitude of the underwater vehicle is updated through the Newton-Euler equation according to the control parameters output by the fuzzy control algorithm.

7. A full-process safety control system for underwater recovery of underwater vehicles by a mother ship, characterized in that: Used to execute the control method according to any one of claims 1 to 6, comprising: Return route planning module: used to obtain the mother ship's position through the acoustic positioning system, plan the return route based on the A* algorithm, and dynamically adjust the desired speed according to the real-time ocean current speed; Adjustment section position and attitude adjustment module: used to activate the optical recognition system to identify the dock feature mark when approaching the mother ship at a set distance, calculate the relative position and attitude deviation, and control the thruster and rudder adjustment; Real-time attitude adjustment module during docking: used to obtain current velocity deviation and attitude deviation through current sensors and IMU, and generate thruster and rudder control parameters using fuzzy control algorithm; Safety monitoring and emergency response module: used to monitor location, posture, and power information in real time. When the abnormality exceeds the threshold, it triggers path replanning or backup power system. The cost function of the path replanning includes the path length and the time domain accumulation of the ocean current influence.

8. The whole process safety control system for underwater recovery of underwater vehicles by a mother ship according to claim 7 is characterized by: The safety monitoring and emergency handling module includes: Adaptive modulation and coding unit, dynamically adjusts the modulation mode and coding rate according to the channel signal-to-noise ratio; The quaternion attitude analysis unit determines abnormalities by calculating the quaternion modulus length of the attitude error.

Images