Whole-process safety control method for recovering underwater vehicle underwater by mother ship

Abstract

The invention provides a whole-process safety control method for recovering an underwater vehicle underwater by a mother ship, which comprises the following steps of: planning a return flight near-section path: acquiring the position of the mother ship, planning a return flight path by adopting an A * algorithm, and dynamically adjusting an expected speed; adjusting the position and attitude of the adjusting section: when the underwater vehicle is close to the mother ship to a set distance, starting an optical identification system to identify a dock cabin entrance feature identifier, calculating relative position deviation and attitude deviation, and adjusting by using a propeller and a control surface; adjusting the attitude of the docking section in real time: acquiring ocean current speed deviation and attitude deviation, and generating control parameters of a propeller and a control surface by adopting a fuzzy control algorithm; the position, attitude and electric quantity information of the underwater vehicle is monitored in real time, and when it is monitored that at least one of position deviation, attitude error and electric quantity exceeds a corresponding threshold value, at least one of the following emergency operations is executed: a path is re-planned; and starting the standby power system.

Description

Technical Field

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

[0002] With the continuous deepening of ocean development and scientific research, underwater vehicles play an increasingly important role in the fields of ocean environmental monitoring, resource exploration, military reconnaissance, etc. After the underwater vehicle completes its mission, it needs to be safely and efficiently recovered to the mother ship for subsequent maintenance, data processing, and redeployment. However, the process of a mother ship recovering an underwater vehicle underwater is complex and challenging, involving multiple links and various technologies, and there are still many problems to be solved.

[0003] From the perspective of the ocean environment, the ocean environment is complex and changeable, and factors such as ocean currents, waves, and tides will have a significant impact on 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 predetermined recovery path, increasing the difficulty and risk of recovery. The undulation of waves will cause the mother ship to shake, affecting the stability of the docking bay and the docking accuracy between the underwater vehicle and the docking bay. The rise and fall of tides will change the depth and pressure of seawater, affecting the buoyancy and attitude of the underwater vehicle. In addition, marine organisms and debris in the ocean may also interfere with the recovery process of the underwater vehicle. For example, seaweed may entangle the propeller of the underwater vehicle, affecting its normal operation.

[0004] In terms of the navigation and positioning of underwater vehicles, the current technology still has certain limitations. The underwater environment has a strong attenuation effect on the propagation of electromagnetic waves, making it difficult to effectively apply traditional radio navigation technology underwater. Although acoustic navigation technology has been widely used underwater, acoustic signals are easily interfered by factors such as ocean noise and multipath effects, resulting in low positioning accuracy. In addition, when the underwater vehicle approaches the mother ship, it needs to obtain the accurate position and attitude information of the mother ship and the docking bay in real time for path planning and attitude adjustment. However, the accuracy and real-time performance of existing positioning technologies in the short-range cannot meet the requirements for the safe recovery of underwater vehicles.

[0005] In terms of the control of the recovery process, there is currently a lack of a complete and effective safety control method and system for the entire process. During the process of the underwater vehicle returning to the dock from its return journey, it needs to go through multiple stages, and each stage has different tasks and requirements. For example, in the near return stage, the underwater vehicle needs to plan its own path according to the position of the mother ship and continuously approach the mother ship; in the adjustment stage, it needs to identify the position 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 sea current conditions and its own dynamic characteristics to avoid collisions. However, the 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 easily leads to mistakes and accidents during the recovery process.

[0006] In addition, the current recovery system also has deficiencies in terms of reliability and safety. The hardware equipment of the recovery system is vulnerable to corrosion and damage in the marine environment, resulting in system failures. At the same time, the degree of automation in the recovery process is not high, and there are many links that require manual intervention, increasing the work intensity of the operators and the risk of human errors. Once an unexpected situation occurs during the recovery process, the existing recovery system may not be able to take timely and effective countermeasures, thus affecting the safe recovery of the underwater vehicle. Summary of the Invention

[0007] Aiming at the defects and deficiencies of the existing technology, the present invention provides a full-process safety control method and system for the mother ship to recover the underwater vehicle underwater, and its core innovative design is as follows:

[0008] Multi-stage collaborative control architecture: The recovery process is split into three stages: the near return stage, the adjustment stage, and the docking stage. Through seamless switching of different technologies such as acoustic positioning (long-distance navigation), optical recognition (close-range precise positioning), and fuzzy control (disturbance-resistant attitude adjustment), the whole-process coordinated control from path planning to precise docking is realized, solving the problem of lack of overall planning in the existing technology.

[0009] Marine environment adaptive mechanism:

[0010] In the return stage, the sea current speed is dynamically fused to real-time correct the expected speed, and the cumulative impact of the sea current on the path is quantified (joint optimization through path length and the time-domain cumulative effect of the sea current);

[0011] In the docking stage, anti-disturbance control parameters are generated based on the fuzzy rule reasoning of the sea current deviation and the attitude deviation, improving the robustness under complex sea conditions.

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

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

[0014] Quaternion attitude error threshold determination combined with adaptive modulation and coding transmission is used to construct a whole-process safety monitoring system integrating anomaly detection, replanning, and standby power linkage, significantly improving the recovery reliability.

[0015] The solution adopted by the present invention to solve its technical problems specifically includes:

[0016] A whole-process safety control method for a mother ship to recover an underwater vehicle underwater, including:

[0017] Returning near-segment path planning: Obtain the position of the mother ship through an acoustic positioning system, use the A* algorithm to plan the return path, and dynamically adjust the desired speed according to the sea current speed monitored in real time;

[0018] Adjustment section position and attitude adjustment: When the underwater vehicle approaches the mother ship to a set distance, start the optical recognition system to identify the feature identifier of the docking bay entrance, calculate the relative position deviation and attitude deviation, and use the thrusters and rudder surfaces for adjustment;

[0019] In-docking section attitude real-time adjustment: Obtain the sea current speed deviation and attitude deviation through a sea current sensor and an inertial measurement unit, and use a fuzzy control algorithm to generate the control parameters of the thrusters and rudder surfaces;

[0020] Whole-process safety monitoring and emergency handling: Real-time monitor the position, attitude, and power information of the underwater vehicle. When at least one of the monitored position deviation, attitude error, or power exceeds the corresponding threshold, perform at least one of the following emergency operations:

[0021] Re-plan the path, where the cost function of the path includes the path length and the cumulative cost affected by the sea current;

[0022] Start the standby power system.

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

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

[0025] Combined with the acoustic beacon information at at least three different positions, use the trilateration principle to determine the position of the underwater vehicle relative to the mother ship.

[0026] Furthermore, the optical recognition system includes:

[0027] Process the underwater image using an adaptive image enhancement algorithm;

[0028] Based on the HSV color space and shape features, jointly identify the feature identifier of the docking bay entrance.

[0029] Furthermore, the fuzzy control algorithm includes:

[0030] Take the ocean current speed deviation and attitude deviation as input variables and perform fuzzy processing;

[0031] Infer and generate control parameters according to the preset fuzzy control rules;

[0032] Obtain the precise control parameters of the thruster and rudder surface through defuzzification.

[0033] Furthermore, the position deviation is obtained by calculating the deviation between the current pose and the predetermined path, and it is determined as abnormal when the deviation magnitude exceeds the position deviation threshold;

[0034] The attitude error is determined as abnormal by comparing the magnitude of the attitude error quaternion with the attitude error threshold.

[0035] Furthermore, the cost function for replanning the path includes:

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

[0037] The ocean current cumulative cost: including the time-domain cumulative amount of the influence of the ocean current on the path, and the time-domain cumulative amount is realized by integrating or discretely summing the modulus value of the ocean current velocity vector in the time dimension;

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

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

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

[0041] And, a full-process safety control system for a mother ship to recover an underwater vehicle underwater, including:

[0042] Returning near-section path planning module: used to obtain the position of the mother ship through the acoustic positioning system, plan the return path 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 start the optical recognition system to identify the docking bay feature identifier when approaching the set distance from the mother ship, calculate the relative position and attitude deviation, and control the adjustment of the thruster and rudder surface;

[0044] Docking section attitude real-time adjustment module: used to obtain the ocean current speed deviation and attitude deviation through the ocean current sensor and IMU, and generate the control parameters of the thruster and rudder surface by using the fuzzy control algorithm;

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

[0046] Among them, the cost function of the path replanning includes the path length and the time-domain cumulative amount of the influence of ocean currents.

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

[0048] An adaptive modulation and coding unit that dynamically adjusts the modulation method and coding rate according to the channel signal-to-noise ratio;

[0049] A quaternion attitude analysis unit that determines abnormalities by calculating the norm of the attitude error quaternion.

[0050] In addition, an electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the steps of the above method.

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

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

[0053] Improved full-process coordinated control ability: Through the multi-stage collaborative control architecture of the return segment - adjustment segment - docking segment, combined with the closed-loop of the differential technology chain of acoustic positioning, optical recognition and fuzzy control, it solves the problem of the fragmented recovery process in the prior art, realizes the efficient connection from path planning to precise docking, and significantly improves the fluency and reliability of the recovery process.

[0054] Enhanced adaptability to complex marine environments:

[0055] In the return segment, the ocean current speed is dynamically fused to correct the ship speed in real time, and the cumulative influence of the ocean current on the path is quantified, effectively suppressing the path deviation caused by ocean current interference;

[0056] In the docking segment, anti-disturbance control parameters are generated based on the fuzzy rule reasoning of the ocean current deviation and attitude deviation, improving the attitude stability in a strong disturbance environment.

[0057] Optimized safety and robustness:

[0058] The fusion and complementarity of acoustic and optical positioning overcome the limitations of single technologies and improve the far / near-range navigation and positioning accuracy;

[0059] Quaternion attitude anomaly threshold determination combined with adaptive communication guarantee to construct a safety closed-loop of real-time monitoring - dynamic replanning - emergency power linkage, greatly reducing the risks of collision and out-of-control.

[0060] Cooperative gain:

[0061] Adaptive image enhancement in optical recognition improves the ability to capture feature identifiers, ensuring the accuracy of close-range docking;

[0062] Path replanning introduces a sea current time-domain cumulative cost factor to optimize the balance between path efficiency and safety under complex sea conditions. Description of the Drawings

[0063] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0064] Figure 1 It is a schematic diagram of the specific implementation module of the system according to the embodiment of the present invention. Specific Embodiments

[0065] To make the features and advantages of the present invention more obvious and understandable, specific embodiments are given below for detailed description as follows:

[0066] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the technical field 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] An embodiment of the present invention provides a full - process safety control method for a mother ship to recover an underwater vehicle underwater, aiming to solve problems in the prior art such as large impact of the marine environment, low navigation and positioning accuracy, lack of full - process control, and insufficient reliability and safety when the mother ship recovers the underwater vehicle underwater, and to achieve the safe and efficient recovery of the underwater vehicle from the return journey to docking. Its core technical solutions include: in the near - return stage, the underwater vehicle obtains the position of the mother ship through an acoustic positioning system, plans the return path based on the A* algorithm, and adjusts it in real - time according to the marine environment information; in the adjustment stage, the optical recognition system is started to identify the characteristic marks of the docking bay entrance, the relative position and attitude deviation are calculated, and the position and attitude are adjusted by using the thrusters and rudder surfaces; in the docking stage, information is obtained by means of a sea - current sensor and an inertial measurement unit, the thrusters and rudder surfaces are adjusted by using a fuzzy control algorithm, and at the same time, collision prevention is carried out through an ultrasonic ranging sensor; a full - process safety monitoring system is also established to monitor and process abnormal situations in real - time. The present invention has the advantages of improving recovery safety, enhancing navigation and positioning accuracy, realizing full - process coordinated control, and adapting to complex marine environments.

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

[0070] Path planning in the near - return stage: The underwater vehicle obtains the position information of the mother ship through an acoustic positioning system, plans the return path by using a path - planning method based on the A* algorithm, and adjusts the path according to the marine environment information monitored in real - time;

[0071] Position and attitude adjustment in the adjustment stage: After the underwater vehicle approaches the mother ship by a certain distance, the optical recognition system is started to identify the characteristic marks of the docking bay entrance, the relative position and attitude deviation are calculated, and the position and attitude are adjusted by using the thrusters and rudder surfaces;

[0072] Real - time attitude adjustment in the docking stage: The underwater vehicle monitors the sea - current situation and its own dynamic characteristics in real - time in the docking stage, adjusts the thrusters and rudder surfaces by using a fuzzy control algorithm, and at the same time monitors the distance from the ultrasonic ranging sensor at the docking bay entrance to the inner wall of the docking bay, and takes measures when the distance is less than the safety threshold;

[0073] Full - process safety monitoring and emergency handling: A safety monitoring system is established to monitor the state of the underwater vehicle, the marine environment, and the state information of the docking bay in real - time, and an emergency handling program is started when abnormal situations are detected.

[0074] Among them, the way for the acoustic positioning system to obtain the position information of the mother ship is as follows: The underwater vehicle is equipped with an acoustic receiver, and 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 signals, and determines the relative position by using the trilateration principle in combination with the information of multiple acoustic beacons.

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

[0076] When the optical recognition system recognizes the feature identifier of the docking bay entrance, an adaptive image enhancement algorithm is used to improve the image quality, and a joint recognition algorithm based on color space and shape features is used for feature identifier recognition.

[0077] When the fuzzy control algorithm is adopted in the docking section, the inputs of the fuzzy controller are determined as the sea current speed deviation and the attitude deviation, and the outputs are the control parameters of the thrusters and the rudder surfaces. Fuzzification processing is performed on the input and output variables, fuzzy control rules are formulated, and precise control parameters are obtained through inference synthesis and defuzzification.

[0078] In the whole-process safety monitoring and emergency handling, information collection is carried out by various sensors, an adaptive modulation and coding technology is adopted for information transmission, and the data analysis module judges whether it is abnormal by calculating the position deviation, attitude error, power, etc. and comparing with the corresponding thresholds. The emergency handling procedure includes issuing an alarm, adjusting the operating parameters, and starting the standby power system.

[0079] Based on the above methods, the embodiment of the present invention further provides a whole-process safety control system for a mother ship to recover an underwater vehicle underwater, including:

[0080] Returning near-section path planning module: used to obtain the position information of the mother ship through an acoustic positioning system, plan the return path based on the A* algorithm, and adjust the path in real time according to the ocean environment information;

[0081] Adjusting section position and attitude adjustment module: used to start the optical recognition system to recognize the feature identifier of the docking bay entrance after the underwater vehicle approaches the mother ship by a certain distance, calculate the relative position and attitude deviation, and control the thrusters and the rudder surfaces for adjustment;

[0082] Docking section attitude real-time adjustment module: used to monitor the sea current situation and its own dynamic characteristics in real time, adopt the fuzzy control algorithm to adjust the thrusters and the rudder surfaces, and monitor the distance from the inner wall of the docking bay through an ultrasonic ranging sensor and take measures;

[0083] Whole-process safety monitoring and emergency handling module: used to establish a safety monitoring system, monitor relevant information in real time, and start the emergency handling procedure when an abnormality occurs.

[0084] The following is a more specific introduction to the solution of the embodiment of the present invention:

[0085] 1. Returning near-section path planning

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

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

[0088] Assume that the underwater vehicle receives signals from multiple acoustic beacons of the mother ship simultaneously. Using the trilateration principle and combining the information of at least three acoustic beacons at different positions, the position of the underwater vehicle relative to the mother ship can be determined. Let the coordinates of the jth acoustic beacon be , and the coordinates of the underwater vehicle be , then there are:

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

[0090] 1.2 Initial path planning based on the 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 marine environment is abstracted into a two-dimensional or three-dimensional grid map, and each grid represents a feasible position. Let the current position of the underwater vehicle be the starting point , and the position of the mother ship be the end point .

[0092] The A* algorithm maintains two lists: the open list and the closed list . The open list contains the nodes to be explored, and the closed list contains the nodes that have been explored. For each node , two cost functions are defined:

[0093] : The actual cost from the starting point to the node .

[0094] : The estimated cost from the node to the end point The estimated cost is calculated using a heuristic function such as the Manhattan distance or the Euclidean distance.

[0095] : from the starting point passing through the node to the ending point of the total estimated cost.

[0096] The algorithm steps are as follows:

[0097] Add the starting point to the open list .

[0098] When the open list is not empty:

[0099] Select from the open list the node with the minimum .

[0100] If is the ending point , the path planning is completed, and backtrack the path.

[0101] Remove the node from the open list and add it to the closed list .

[0102] Traverse all adjacent nodes of the node : :

[0103] If is in the closed list , ignore it.

[0104] Calculate the new cost from the starting point passing through the node to the node , where is the cost from the node to the node to the node .

[0105] If is not in the open list , add it to the open list , and set , calculated using the heuristic function, .

[0106] If is already in the open list in, and , update , .

[0107] 1.3 Real-time Path Adjustment Considering the Marine Environment

[0108] The marine environment is complex and changeable, and factors such as ocean currents, water temperature, and salinity will affect the navigation of underwater vehicles. Ocean currents will cause underwater vehicles to deviate from the predetermined path, so it is necessary to consider the impact of ocean currents in real time. Let the ocean current speed be , and the desired speed of the underwater vehicle be , then the actual speed of the underwater vehicle is:

[0109] In order to make the underwater vehicle navigate along the predetermined path, it is necessary to adjust the desired speed according to the ocean current situation. Let the current position of the underwater vehicle be , and the next target position on the path be , then the desired speed can be calculated according to the following formula:

[0110] where is the estimated navigation time of the underwater vehicle from position to position . During the navigation process, continuously monitor the ocean current information and adjust the desired speed in real time to ensure that the underwater vehicle can accurately and quickly approach the mother ship. At the same time, combined with other marine environment information, such as the impact of water temperature and salinity on the acoustic signal propagation speed, correct the acoustic positioning results to improve the accuracy of path planning.

[0111] 2. Adjustment of the Position and Attitude of the Adjustment Section

[0112] 2.1 Activation of the Optical Recognition System and Search for Feature Identifications

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

[0114] where is the transformation function, Parameters related to local image features, obtained by analyzing features such as brightness and contrast in local image regions.

[0115] The camera starts to search for the feature identification of the docking bay entrance in a certain scanning mode. These feature identifications are usually marks of specific colors, unique shapes, etc. To accurately identify these features, a joint recognition algorithm based on color space and shape features is adopted. First, the image is converted from the RGB color space to the HSV color space. Let , , be the hue, saturation, and brightness components respectively. For feature identifications of specific colors, by setting the threshold ranges of , , , the possible regions are initially screened out.

[0116] 2.2 Relative Position and Attitude Deviation Calculation

[0117] After identifying the feature identification, the image processing module further analyzes the image. Let the position of the underwater vehicle in the image coordinate system be , and the position of the docking bay entrance feature identification in the image coordinate system be . Then the relative position deviation on the image plane is:

[0118] To convert the relative position deviation on the image plane into the relative position deviation in the actual space, camera calibration is required. Let the internal parameter matrix of the camera be , and the external parameter matrix be , where is the rotation matrix, is the translation vector. According to the camera imaging model, the relative position deviation in the actual space can be calculated by the following formula:

[0119] By solving the above equations, can be obtained.

[0120] For the calculation of attitude deviation, a method based on feature point matching and rotation matrix decomposition is adopted. Feature points of the feature identification are extracted from the image, and corresponding points in different image frames are found through the feature point matching algorithm. Let the coordinates of the feature points in the initial attitude be , and the coordinates of the feature points in the current attitude be . Then the attitude change is represented by calculating the rotation matrix . The rotation matrix can be decomposed into rotation angles around , , axes , namely:

[0121] Among them, , , are respectively the rotation matrices rotating around , , axis by , , angles. By decomposing the rotation matrix , the attitude deviation can be obtained.

[0122] 2.3 Position and Attitude Adjustment Control

[0123] The control module issues control commands to the thrusters and rudder surfaces according to the calculated relative position and attitude deviations. Let the thrust of the thruster be , and the deflection angle of the rudder surface be . The control law can adopt the PID control algorithm. For the position deviation , the thrust control law of the thruster is:

[0124] Among them, , , are respectively the proportional, integral, and differential coefficients.

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

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

[0127] By continuously adjusting the thrust of the thruster and the deflection angle of the rudder surface, the axis of the underwater vehicle is made to coincide as much as possible with the axis of the dock entrance. During the adjustment process, the above-mentioned identification, calculation, and control steps are continuously repeated until the position and attitude of the underwater vehicle meet the docking requirements.

[0128] 3. Real-time Attitude Adjustment in the Docking Section

[0129] In the docking section of the mother ship to recover the underwater vehicle underwater, the underwater vehicle faces a complex marine environment and strict attitude control requirements. In this stage, the attitude of the underwater vehicle needs to be adjusted in real time to ensure its safe and accurate entry into the dock and avoid collision with the inner wall of the dock. The following will elaborate in detail on the technical details of real-time attitude adjustment in the docking section.

[0130] 3.1 Acquisition of Sea Current Information and Attitude Information

[0131] The surface of the underwater vehicle is equipped with a sea current sensor and an Inertial Measurement Unit (IMU) to obtain the surrounding sea current conditions and its own attitude information in real time. The sea current sensor can measure the speed and direction of the sea current, where is a two-dimensional vector, representing the speed components of the sea current in and directions respectively; represents the angle between the sea 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 important bases for attitude adjustment.

[0133] 3.2 Design of Fuzzy Control Algorithm

[0134] In order to adjust the thrusters and rudder surfaces of the underwater vehicle in real time according to the sea current information and attitude information, a fuzzy control algorithm is adopted. The fuzzy control algorithm has the advantages of not relying on an accurate mathematical model and having strong robustness to system parameter changes, and is suitable for complex underwater environments.

[0135] First, determine the input and output variables of the fuzzy controller. The input variables are the sea current speed deviation , attitude deviation (including , , ), and the output variables are the control parameters of the thrusters and the control parameters of the rudder surfaces.

[0136] Fuzzify the input and output variables, divide them into different fuzzy sets, and determine the membership functions of each fuzzy set. For example, for the sea current speed deviation , it can be divided into fuzzy sets such as "Negative Big (NB)", "Negative Medium (NM)", "Negative Small (NS)", "Zero (ZO)", "Positive Small (PS)", "Positive Medium (PM)", "Positive Big (PB)", etc., and its membership function can adopt a triangular or trapezoidal membership function.

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

[0138] Inference and synthesis are performed on the fuzzy control rules to obtain a fuzzy output. Finally, through defuzzification processing, the fuzzy output is converted into precise control parameters and 。Common defuzzification methods include the centroid method, the maximum membership degree method, etc.

[0139] 3.3 Attitude adjustment model establishment

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

[0141]

[0142] Among them, 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; is the gravity and buoyancy vector; is the control input vector, including the forces and torques generated by the thrusters and rudders.

[0143] During the attitude adjustment process, according to the control parameters and obtained from the fuzzy control algorithm, the control input vector is calculated. Then, by solving the above - mentioned dynamic equations, the acceleration of the underwater vehicle is obtained, and further, the velocity and attitude information of the underwater vehicle are updated.

[0144] 3.4 Collision warning and handling

[0145] An ultrasonic ranging sensor is set at the dock entrance to continuously monitor the distance between the underwater vehicle and the inner wall of the dock . When the distance is less than the safety threshold , the system issues an alarm and takes corresponding measures.

[0146] Collision warning can adopt a threshold - based method, that is, when When it is determined that a collision may occur. At this time, the power of the thruster and the angle of the rudder surface can be adjusted to keep the underwater vehicle away from the inner wall of the dock compartment. For example, reduce the power of the thruster and at the same time adjust the control parameters of the rudder surface to change the course of the underwater vehicle.

[0147] Through the above technical means, the real-time adjustment of the attitude of the underwater vehicle in the docking section is realized, ensuring that the underwater vehicle enters the dock compartment safely and accurately in a complex marine environment.

[0148] 4. Whole-process safety monitoring and emergency handling

[0149] 4.1 Information collection and transmission

[0150] The whole-process safety monitoring system needs to collect the status information of the underwater vehicle, the marine environment information and the dock compartment status information in real time. The status information of the underwater vehicle includes position , attitude , speed , battery level , etc. The marine environment information includes sea current speed , sea current direction , water temperature , salinity , etc. The dock compartment status information includes dock compartment position , dock compartment attitude , etc.

[0151] These information are collected by various sensors distributed on the underwater vehicle, marine environment monitoring equipment and dock compartment. The collected information is transmitted to the monitoring center through wired or wireless communication links. In order to ensure the reliability and real-time of information transmission, adaptive modulation coding technology is adopted to dynamically adjust the modulation mode and coding rate according to the signal-to-noise ratio of the channel . Let the initial modulation mode be , and the coding rate be . When changes, adjust according to the following rules:

[0152] where and are functions determined according to the channel characteristics and communication protocols.

[0153] 4.2 Data analysis and anomaly judgment

[0154] The data analysis module of the monitoring center analyzes the collected information to judge whether there are abnormal situations. For the position information of the underwater vehicle, calculate its deviation from the predetermined path To determine whether there is a deviation. Let the expected position on the predetermined path be , then:

[0155] When ( is the position deviation threshold), it is determined that the position is abnormal.

[0156] For the attitude information, the attitude error is calculated to determine whether it is abnormal. The attitude is represented by quaternions. Let the expected attitude be , and the current attitude be , then the attitude error quaternion is:

[0157] When ( is the attitude error threshold), it is determined that the attitude is abnormal.

[0158] For the power information, when ( is the power threshold), it is determined that the power is too low and abnormal.

[0159] For the marine environment information and the dock compartment status information, corresponding thresholds are also set respectively for abnormality judgment.

[0160] 4.3 Emergency Handling Procedures

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

[0162] 4.3.1 Sound the Alarm When an abnormal situation is detected, the system immediately sounds an alarm through the audible and visual alarm device, and at the same time sends an alarm message to the operator's terminal device. The alarm message includes the type of abnormality, the time and location of the abnormality occurrence, etc.

[0163] 4.3.2 Adjust the Operating Parameters According to the type of abnormality, adjust the operating parameters of the underwater vehicle. For example, when the position deviates, re-plan the path. Let the new target position be , and use the improved A* algorithm for path planning, considering the influence of marine environmental factors on the path. The path cost function is defined as:

[0164] Where is the path length, and are the weight coefficients, represents the cumulative cost affected by the ocean current on the path.

[0165] When the attitude is abnormal, adjust the control parameters of the thrusters and rudder surfaces, and use a feedback control algorithm to restore the attitude to normal. Let the attitude error be , and the control input is:

[0166] where and are the proportional and derivative control coefficients respectively.

[0167] 4.3.3 Start the backup power system When the battery power is too low, start the backup power system. The backup power system can be a battery pack or other energy devices to ensure that the underwater vehicle can continue to complete the recovery task or safely float and wait for rescue.

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

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

[0170] Improve recovery safety: Through the whole-process safety monitoring and emergency handling system, information such as the status of the underwater vehicle, the marine environment, and the status of the docking bay is collected in real time, and the abnormal situation is judged by the data analysis module. Once an abnormality is detected, the emergency handling module automatically starts the emergency handling procedure, such as issuing an alarm, adjusting the operating parameters, starting the backup power system, etc., effectively reducing the risk of accidents such as collisions and damages during the recovery process of the underwater vehicle and improving the recovery safety.

[0171] Enhance navigation and positioning accuracy: Use an acoustic positioning system to obtain the position of the mother ship, and use the trilateration principle to determine the relative position of the underwater vehicle; after approaching the mother ship at a certain distance, start the optical recognition system to identify the characteristic marks of the docking bay entrance, and calculate the relative position and attitude deviation by combining camera calibration and the method based on feature point matching and rotation matrix decomposition. The combination of acoustic positioning and optical recognition systems makes up for the deficiencies of single positioning technologies, improves the navigation and positioning accuracy, and ensures that the underwater vehicle accurately approaches and enters the docking bay.

[0172] Achieve coordinated control throughout the process: Overall consideration is given to the whole process of the underwater vehicle from returning to the dock, and different control strategies are adopted in different stages. In the near return stage, the path is planned based on the A* algorithm and adjusted in real time according to the marine environment; in the adjustment stage, the position and attitude are adjusted through the optical recognition system and the PID control algorithm; in the docking stage, the attitude is adjusted by using the fuzzy control algorithm and the Newton-Euler equation modeling. Each stage is closely coordinated to make the recovery process more efficient and smooth.

[0173] Adapt to complex marine environments: fully consider marine environmental factors during path planning and attitude adjustment. For example, during the near-return path planning, adjust the desired speed according to the sea current speed Adjust the desired speed , and the formula is . , and at the same time, correct the acoustic positioning results by combining water temperature, salinity, etc.; during the docking section, obtain sea current and attitude information through sea current sensors and IMUs, and use a fuzzy control algorithm to adjust the thrusters and rudder surfaces. These measures enable the system to adjust the operating parameters of the underwater vehicle in real time according to changes in the marine environment, improving its adaptability to complex marine environments.

[0174] Based on the above design method, the module architecture and data interaction process of the system provided by the embodiments of the present invention can be obtained as Figure 1 shown, mainly including a near-return path planning module (A), an optical recognition module (G) in the adjustment section, a sea current detection module (K) in the docking section, and a full-process safety monitoring center (O). The near-return path planning module (A) obtains the mother ship position data through the acoustic positioning module (B), combines the coordinate information of the multi-beacon fusion positioning module (D), generates an initial path by the A* algorithm core module (E), and corrects the path in real time according to the sea current environment through the dynamic path adjustment module (C). Finally, the propulsion control module (F) executes the navigation instructions. In the adjustment section, the optical recognition module (G) captures the feature identification of the docking bay. After the feature identification extraction module (H) calculates the coordinate deviation, the attitude solution module (I) generates a control instruction to drive the rudder surface adjustment module (J) to complete attitude calibration. In the docking section, the sea current detection module (K) collects the flow velocity and real-time attitude data. The fuzzy control decision-making module (L) combines the feedback of the dynamics model module (M) to generate control parameters, and the thruster coordination module (N) realizes precise attitude adjustment. The safety monitoring center (O) integrates an abnormal diagnosis module (P) to analyze the system state in real time, triggers the audible and visual alarm device (R), and coordinates the power switching module (Q) and the emergency propulsion system (S) to handle abnormal conditions. Each module realizes full-process coordination through stage switching signals and data streams. Among them, the closed-loop control between path planning, attitude adjustment, and the dynamics model is dynamically coupled through the formulas and to ensure the safe and efficient operation of the system in complex marine environments.

[0175] Based on the same inventive concept, the present invention further 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 configured to execute the program instructions stored in the memory. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), 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, and is used to implement one or more instructions. Specifically, it is used to load and execute one or more instructions in the computer storage medium to implement the above method.

[0176] It should be further noted that, based on the same inventive concept, the present invention further provides a computer storage medium, on which a computer program is stored, and the computer program, when run by a processor, executes the above method. The storage medium may adopt 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, for example, but not be limited to, an electrical, magnetic, optical, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the computer-readable storage medium include: an electrical connection having one or more wires, a portable computer disk, a hard disk, a Random Access Memory (RAM), a Read-Only Memory (ROM), an Erasable Programmable Read-Only Memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, the computer-readable storage medium may be any tangible medium that contains or stores a program, and the program may be used by or combined with an instruction execution system, apparatus, or device.

[0177] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those with ordinary skills in the field to which the present invention pertains. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "comprising" or "including" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0178] As described above, it is only the preferred embodiment of the present invention, and it is not a limitation of the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

[0179] The present invention is not limited to the above best mode. Anyone inspired by the present invention can obtain various other forms of a full-process safety control method for underwater recovery of an underwater vehicle by a mother ship. All equal changes and modifications made according to the scope of the present invention application shall fall within the coverage scope of the present invention.

Claims

1. A full - process safety control method for a mother ship to recover an underwater vehicle underwater, characterized in that, Including: Near - return path planning: Obtain the position of the mother ship through an acoustic positioning system, use the A* algorithm to plan the return path, and dynamically adjust the desired speed according to the sea current speed monitored in real - time; Adjustment of position and attitude in the adjustment section: When the underwater vehicle approaches the mother ship to a set distance, start the optical recognition system to identify the characteristic marks of the docking bay entrance, calculate the relative position deviation and attitude deviation, and use the thrusters and rudder surfaces for adjustment; Real - time attitude adjustment in the docking section: Obtain the sea current speed deviation and attitude deviation through the sea current sensor and inertial measurement unit, and use the fuzzy control algorithm to generate the control parameters of the thrusters and rudder surfaces; Full - process safety monitoring and emergency handling: Monitor the position, attitude and power information of the underwater vehicle in real - time. When at least one of the monitored position deviation, attitude error or power exceeds the corresponding threshold, perform at least one of the following emergency operations: Re - plan the path, where the cost function of the path includes the path length and the cumulative cost affected by the sea current; Start the backup power system.

2. A full - process safety control method for a mother ship to recover an underwater vehicle underwater according to claim 1, characterized in that: The acoustic positioning system is implemented in the following way: The underwater vehicle receives the acoustic signal emitted by the mother ship's acoustic beacon and calculates the distance from the mother ship by measuring the propagation time of the acoustic signal; Combining the information of at least three acoustic beacons at different positions, and using the trilateration principle to determine the position of the underwater vehicle relative to the mother ship.

3. A full - process safety control method for a mother ship to recover an underwater vehicle underwater according to claim 1, characterized in that: The optical recognition system includes: Process the underwater image using an adaptive image enhancement algorithm; Jointly identify the characteristic marks of the docking bay entrance based on the HSV color space and shape features.

4. A full - process safety control method for a mother ship to recover an underwater vehicle underwater according to claim 1, characterized in that: The fuzzy control algorithm includes: Take the sea current speed deviation and attitude deviation as input variables and perform fuzzy processing; Infer and generate control parameters according to the preset fuzzy control rules; Obtain the precise control parameters of the thrusters and rudder surfaces through defuzzification.

5. A full - process safety control method for a mother ship to recover an underwater vehicle underwater according to claim 1, characterized in that: The position deviation is obtained by calculating the deviation between the current pose and the predetermined path, and is determined to be abnormal when the deviation norm exceeds the position deviation threshold; The attitude error is determined to be abnormal by comparing the norm of the attitude error quaternion with the attitude error threshold.

6. A full - process safety control method for a mother ship to recover an underwater vehicle underwater according to claim 1, characterized in that: The cost function of the re - planned path includes: The basic path cost including the path length; The sea current cumulative cost: including the time - domain cumulative amount of the influence of the sea current on the path, and the time - domain cumulative amount is realized by the integral or discrete summation of the modulus value of the sea current velocity vector in the time dimension; Joint optimization: Linearly combine the basic path cost and the sea current cumulative cost, and the weight coefficient is dynamically adjusted according to the sea current intensity.

7. The full-process safety control method for a mother ship to recover an underwater vehicle underwater according to claim 1, characterized in that: The information transmission of the safety monitoring adopts adaptive modulation and coding technology, and dynamically adjusts the modulation mode and coding rate according to the channel signal-to-noise ratio.

8. The full-process safety control method for a mother ship to recover an underwater vehicle underwater according to claim 1, characterized in that: During the real-time attitude adjustment of the docking section, according to the control parameters output by the fuzzy control algorithm, the attitude of the underwater vehicle is updated through the Newton-Euler equation.

9. A full-process safety control system for a mother ship to recover an underwater vehicle underwater, characterized in that, Including: Returning near-section path planning module: used to obtain the position of the mother ship through the acoustic positioning system, plan the return path based on the A* algorithm, and dynamically adjust the desired speed according to the real-time sea current speed; Adjustment section position and attitude adjustment module: used to start the optical recognition system to identify the docking bay feature identification when approaching the set distance of the mother ship, calculate the relative position and attitude deviation, and control the adjustment of the thruster and rudder surface; Docking section attitude real-time adjustment module: used to obtain the sea current speed deviation and attitude deviation through the sea current sensor and IMU, and generate the control parameters of the thruster and rudder surface by using the fuzzy control algorithm; Safety monitoring and emergency handling module: used to monitor the position, attitude and power information in real time, and trigger path replanning or the standby power system when the abnormality exceeds the threshold; Among them, the cost function of the path replanning includes the path length and the time-domain cumulative amount affected by the sea current.

10. The full-process safety control system for recovering an underwater vehicle by a mother ship underwater according to claim 9, characterized in that: The safety monitoring and emergency handling module includes: Adaptive modulation and coding unit, which dynamically adjusts the modulation mode and coding rate according to the channel signal-to-noise ratio; Quaternion attitude analysis unit, which determines the abnormality by calculating the modulus length of the attitude error quaternion.

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