Bulk cargo ship anchoring stability regulation and control method based on mechanical optimization

Abstract

The invention relates to the field of ship engineering and ocean engineering, and discloses a bulk cargo ship anchoring stability regulation and control method based on mechanical optimization, comprising the following steps: S1, arranging a regulation and control device with a controllable hydrodynamic airfoil on an anchor chain of a ship; s2, the tension and the tension change rate of the anchor chain are obtained in real time, and the yawing motion state of the ship is obtained; s3, selecting between a first regulation and control mode for inhibiting the yawing motion and a second regulation and control mode for inhibiting the impact load of the anchor chain; and S4, determining a target attack angle of the hydrodynamic airfoil according to the selected regulation and control mode, and controlling the hydrodynamic airfoil to be adjusted to the target attack angle so as to generate expected hydrodynamic force. According to the method, the stress state of the anchor chain is monitored in real time and compared with the preset threshold value, dynamic switching between the two regulation and control modes of ship yawing suppression and anchor chain impact load suppression is achieved, and therefore the anchoring composite risk is subjected to coordinated regulation and control.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding and ocean engineering, specifically to a method for controlling the anchoring stability of bulk carriers based on mechanical optimization. Background Technology

[0002] In the field of marine engineering, especially for large vessels such as bulk carriers, single-point anchoring in open waters is a routine and necessary operation. During this period, the vessel is connected to the seabed only by a single anchor chain at the bow to withstand continuous environmental loads such as wind, waves, and currents, and to maintain the vessel's position within the designated waters.

[0003] To address instability during anchoring, existing technologies offer several solutions. One approach involves utilizing the ship's main propulsion system, bow thrusters, or auxiliary tugboats to apply active thrust directly against environmental loads, thereby controlling the ship's attitude. This method effectively and directly alters the ship's motion tendency. Another solution involves connecting highly elastic mooring elements, such as large-diameter nylon tow cables, in series within the anchor chain system. These elastic elements, utilizing their material properties, absorb some of the impact energy through tensile deformation when the anchor chain tension increases sharply, providing a passive buffering effect.

[0004] However, the aforementioned existing technologies have shortcomings in dealing with complex anchoring conditions. While active thrust control methods are direct in their effects, their control is typically based on the ship's attitude or positional deviations, failing to directly monitor and input the instantaneous stress state of the anchor chain as a decision-making input. Therefore, they cannot predict and respond to impending anchor chain impact loads. Passive buffer elements can only absorb energy after the impact occurs, failing to fundamentally suppress the significant bow roll motion that causes impact loads, and their buffering capacity is fixed, unable to adjust according to changes in risk level. Most critically, existing technologies treat suppressing bow roll motion and mitigating impact loads as two independent problems, lacking a coordinated control mechanism capable of real-time assessment of the current primary risk and dynamic switching of control objectives. Therefore, existing technologies cannot effectively and adaptively balance and switch between suppressing routine bow roll motion and responding to sudden impact loads. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for controlling the anchoring stability of bulk carriers based on mechanical optimization. This method solves the problem that existing technologies use independent methods to suppress bow roll and mitigate shocks, making it impossible to adaptively switch between the two control objectives based on the real-time risk of the anchoring system, thus making it difficult to coordinate and address the complex risks of anchoring.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a method for controlling the anchoring stability of bulk carriers based on mechanical optimization, comprising the following steps:

[0008] S1. Install a control device with controllable hydrodynamic fins on the ship's anchor chain.

[0009] S2. Real-time acquisition of the tension and tension change rate of the anchor chain, and acquisition of the bow roll motion state of the ship;

[0010] S3. Based on the comparison results of the tension and the rate of change of tension with a preset threshold, select between a first control mode for suppressing the yaw motion and a second control mode for suppressing the anchor chain impact load;

[0011] S4. Based on the selected control mode, determine the target angle of attack of the hydrodynamic surface, and control the hydrodynamic surface to adjust to the target angle of attack to generate the expected hydrodynamic force, thereby achieving the control of the ship's anchoring stability.

[0012] Preferably, in step S1, the control device for deploying the controllable hydrodynamic surface specifically includes:

[0013] The control device is fixed to the anchor chain by a universal rotating gripper;

[0014] The universal rotating gripper axially locks the control device and the anchor chain while allowing the anchor chain to rotate freely around its own axis, thus isolating the influence of the anchor chain torsion on the attitude of the control device.

[0015] Preferably, in step S2, obtaining the tension and tension change rate of the anchor chain includes:

[0016] Using tension sensors installed on the control device, the local tension of the anchor chain at the location of the control device is measured in real time;

[0017] The rate of change of tension is calculated based on the continuous time series data of the local tension.

[0018] In one specific embodiment, in step S2, obtaining the bow roll motion state of the ship includes:

[0019] The ship's position, speed, and heading in the geodetic coordinate system are acquired and recorded in real time using its onboard global positioning system, gyrocompass, or inertial navigation unit.

[0020] Based on the continuous time series data of the heading, the bow roll rate of the ship is calculated, and the position, velocity, heading, and bow roll rate are used together as a characterization of the ship's bow roll motion state.

[0021] Preferably, in step S3, the comparison result between the tension and the rate of change of tension and the preset threshold specifically includes:

[0022] When the real-time acquired tension is lower than a preset tension warning threshold, and the absolute value of the tension change rate is lower than a preset tension change rate critical threshold, a comparison result is generated to indicate the selection of the first control mode.

[0023] When the real-time acquired tension is not lower than the tension warning threshold, or the absolute value of the tension change rate is not lower than the tension change rate critical threshold, a comparison result is generated to indicate the selection of the second control mode.

[0024] Furthermore, in step S3, the selection between the first control mode and the second control mode specifically includes:

[0025] When it is determined that the absolute values ​​of the tension and the rate of change of tension are both lower than the corresponding preset thresholds, the current control mode is selected or maintained in the first control mode.

[0026] When it is determined that at least one of the absolute values ​​of the tension or the rate of change of tension is not lower than the corresponding preset threshold, the current control mode is immediately selected or switched to the second control mode, and a higher execution priority is assigned.

[0027] In one specific embodiment, in step S4, determining the target angle of attack of the hydrodynamic wing surface specifically includes:

[0028] When selecting the first control mode, the goal is to generate a restoring torque that resists the bow roll motion of the ship. Based on the bow roll motion state of the ship, the angle of attack that can generate the maximum lateral damping force of the hydrodynamic wing surface is calculated in real time and determined as the target angle of attack.

[0029] When selecting the second control mode, with the goal of generating a vertical buffering force that weakens the impact load of the anchor chain, the angle of attack that enables the hydrodynamic wing surface to generate the maximum vertical lift is calculated and determined as the target angle of attack.

[0030] Preferably, in step S4, adjusting the hydrodynamic surface to the target angle of attack specifically includes:

[0031] The target angle of attack is generated into a control command, and the control command is sent to the control device via underwater acoustic communication.

[0032] After receiving the control command, the control device drives the hydrodynamic surface to adjust to the target angle of attack through its internal actuator.

[0033] A second aspect of the present invention provides a bulk carrier anchoring stability control system based on mechanical optimization, the system being used to perform the method described in any of the preceding claims, characterized in that it includes:

[0034] The status acquisition module is used to acquire the anchor chain tension measured by the control device deployed on the ship's anchor chain in real time, calculate the tension change rate, and acquire the bow roll motion state of the ship.

[0035] The modal decision module, connected to the state acquisition module, is used to select between a first control mode for suppressing yaw motion and a second control mode for suppressing anchor chain impact load based on the comparison results of tension and tension change rate with a preset threshold.

[0036] The target determination module is connected to the modal decision module and the state acquisition module respectively, and is used to determine the target angle of attack of the hydrodynamic surface based on the selected control mode and in combination with the bow roll motion state of the ship.

[0037] The control execution module is connected to the target determination module. The control execution module is used to generate the target angle of attack into a control command and control the hydrodynamic surfaces in the control device to adjust to the target angle of attack to generate the expected hydrodynamic force.

[0038] Preferably, the control execution module includes:

[0039] The command sending unit is used to generate the target angle of attack into a control command and send the control command via underwater acoustic communication.

[0040] An instruction receiving unit is installed within the control device and is used to receive the control instructions via the underwater acoustic communication method.

[0041] An attitude execution unit, located within the control device, is used to drive the hydrodynamic surface to adjust to the target angle of attack after receiving the control command.

[0042] This invention provides a method for controlling the anchoring stability of bulk carriers based on mechanical optimization. It has the following beneficial effects:

[0043] 1. This invention acquires the tension and rate of change of the anchor chain in real time and dynamically selects between a first control mode for suppressing yaw and a second control mode for suppressing impact loads based on a comparison with a preset threshold. This design allows the method to switch according to the real-time priority of risks in the mooring system. When facing the risk of impact loads, vertical buffering (second control mode) is executed first, while yaw suppression (first control mode) is executed under normal conditions. This collaboratively addresses the complex risks during mooring and improves the targeting of the control.

[0044] 2. This invention sets different optimization objectives for two control modes. In the first control mode, the objective is to generate a restoring moment to resist the ship's yaw motion, and the angle of attack corresponding to the maximum lateral damping force is calculated. In the second control mode, the objective is to generate a vertical buffering force to reduce the impact load of the anchor chain, and the angle of attack corresponding to the maximum vertical lift is calculated. This method utilizes the same hydrodynamic surface and, by changing the calculation strategy for its target angle of attack, achieves the on-demand application of two different physical effects, making the control function more comprehensive.

[0045] 3. This invention uses a universal rotating gripper to fix the control device to the anchor chain. This gripper achieves axial locking while allowing the anchor chain to rotate freely around its own axis. This structural design isolates the anchor chain torsion from interfering with the attitude of the control device, ensuring that the angle of attack of the hydrodynamic surface can be precisely controlled without being affected by the rotational motion of the anchor chain itself, thereby guaranteeing the accuracy of the expected hydrodynamic application and the reliability of the control. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0047] Figure 2 This is a system architecture diagram of the present invention. Detailed Implementation

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Reference Figure 1 One embodiment of the present invention provides a method for controlling the anchoring stability of bulk carriers based on mechanical optimization. This method aims to synergistically suppress the bow roll motion and impact load on the anchor chain of the ship while anchored by using active control devices deployed on the ship's anchor chain.

[0050] First, a control device with controllable hydrodynamic surfaces is installed on the ship's anchor chain. This control device, acting as a hydrodynamic actuator, is located between the hull and the anchor point on the seabed.

[0051] After the control device is deployed, the system enters a real-time monitoring and control cycle. The system acquires data in real time on two aspects: one is the force state of the anchor chain, specifically including the tension and rate of change of the anchor chain; the other is the motion state of the ship, specifically including the bow roll motion of the ship.

[0052] After acquiring the aforementioned state data, the system executes a decision on the control mode. Based on a comparison between the tension and the rate of change of tension and a set of preset thresholds, the system dynamically selects between two preset control modes. The goal of the first control mode is to suppress the bow roll motion of the ship; the goal of the second control mode is to suppress the impact load on the anchor chain.

[0053] After determining the control mode to be executed, the system determines the target angle of attack of the hydrodynamic surface based on the selected control mode. Since the control objectives of the two modes are different, the calculation strategies for determining the target angle of attack are also different. The first control mode aims to generate the maximum lateral damping force, while the second control mode aims to generate the maximum vertical lift.

[0054] Finally, the system controls the hydrodynamic surfaces within the control device to adjust to the determined target angle of attack, causing the hydrodynamic surfaces to generate the expected hydrodynamic force under the action of the water flow. This hydrodynamic force acts on the anchor chain through the control device, thereby applying control or buffering forces to the hull, thus achieving regulation of the ship's anchoring stability. This method, through this closed-loop process, achieves adaptive, dual-modal regulation of anchoring risks.

[0055] Reference Figure 1 The control device is an integrated underwater unit, and its deployment is carried out during the anchoring process of the ship. For example, when the anchor chain is released to the predetermined working depth, the control device is fixed to a specific link of the anchor chain.

[0056] In one specific embodiment, the main housing of the control device encapsulates one or more controllable hydrodynamic surfaces; an actuator (e.g., a high-torque waterproof servo motor) for driving the hydrodynamic surfaces to deflect about their axis of rotation; a microcontroller (MCU) for receiving commands from the shipboard unit and controlling the actuator; a hydroacoustic communication device for bidirectional data exchange with the shipboard unit; and an energy module. The energy module may include a miniature hydrodynamic turbine generator and a backup battery pack for powering the control device in the presence of relative water flow.

[0057] The control device also integrates a sensor array to acquire the status of the control device itself and its surrounding environment. Specifically, the sensor array includes: an inertial measurement unit (IMU) for measuring the wing's own attitude (such as roll and pitch angles), and a sensor array for measuring the relative velocity v between the control device and the surrounding water. rel Acoustic Doppler current meter (ADCP), and pressure sensor for measuring working depth.

[0058] The control device is fixed to the anchor chain via a universal swivel grip. The universal swivel grip is the mechanical interface connecting the control device body to the anchor chain. The grip has an openable locking mechanism; when closed, its internal groove engages tightly with the anchor chain links, thereby locking the control device axially (in the length direction) along the anchor chain and preventing it from sliding axially.

[0059] Simultaneously, the locking mechanism of the omnidirectional rotating grip is connected to the main housing of the control device via a low-friction rotary joint (e.g., a waterproof thrust bearing or swivel). This structure allows the grip to rotate synchronously with the anchor chain as it twists about its own axis (when the grip is engaged). Because of the rotary joint between the grip and the control device body, the torsional motion of the anchor chain is isolated and not transmitted to the main housing of the control device. This design ensures that the attitude control reference of the control device (and its hydrodynamic surfaces) is independent of the torsional state of the anchor chain.

[0060] Reference Figure 1 The status of the anchor chain is obtained in real time by a control device deployed underwater.

[0061] In one specific embodiment, one or more tension sensors are integrated into the internal force-bearing structure of the omnidirectional rotating gripper. When the control device is fixed to the anchor chain via the gripper, the tension sensor can measure in real time the local force transmitted from the anchor chain to the gripper, i.e., the local tension T of the anchor chain at the location of the control device. c .

[0062] The microcontroller inside the control device operates at a preset sampling frequency f. s The local tension T was continuously collected. c (t), forming a time series dataset. The tension change rate This is obtained by performing real-time numerical differencing on the time series data. For example, at time t, the rate of change of tension... It can be approximated using the first-order backward difference formula:

[0063]

[0064] In the formula, T is the rate of change of tension; c (t) represents the continuously collected local tension; T c To regulate the local tension at the location of the control device; T c (t-Δt) represents the local tension value at the previous sampling time; Δt is the sampling time interval. The measured local tension T c (t) and the calculated rate of change of tension It will be transmitted to the shipboard decision unit via an underwater acoustic communication device.

[0065] The acquisition of the ship's bow roll motion is accomplished by shipboard equipment. In one specific embodiment, the shipboard decision unit is connected to the ship's integrated navigation system (INS) or independent navigation sensors.

[0066] Shipborne equipment acquires and records in real time the ship's position data (e.g., latitude and longitude or geodetic coordinates [X(t), Y(t)]) and speed data in the geodetic coordinate system. And the ship's real-time heading ψ(t).

[0067] The shipborne decision unit calculates the ship's bow roll rate r(t) by performing time differentiation based on real-time continuous time series data of bow ψ(t):

[0068]

[0069] In the formula, r(t) is the bow roll rate of the ship; ψ(t) is the real-time heading of the ship; Let represent the first-order differential operator with respect to time t.

[0070] In discrete-time systems, this calculation is also obtained by numerically differencing continuously acquired ψ(t) data or by estimating using a state filter (such as a Kalman filter). Finally, the position, velocity, heading ψ(t), and bow angular velocity r(t) are combined to characterize the bow motion state of the ship.

[0071] Reference Figure 1 Based on the comparison between the tension and the rate of change of tension and a preset threshold, a selection is made between a first control mode for suppressing the yaw motion and a second control mode for suppressing the anchor chain impact load. This step is executed in the shipboard decision unit, and its core is to dynamically select the control target based on a real-time risk assessment of the anchor chain's stress state.

[0072] To execute this decision, the system pre-sets two key thresholds: the tension warning threshold T. warn and the critical threshold of the rate of change of tension The tension warning threshold T warn This is a value used to determine whether the anchor chain tension has entered a warning zone. It can be set based on the minimum breaking load (MBL) or safe working load (SWL) of the anchor chain, for example, as a specific percentage of the safe working load. The tension change rate critical threshold... This is a value used to identify whether there is a sudden change in anchor chain tension. Its setting is designed to capture the characteristic of a sharp increase in tension before an impact load occurs.

[0073] During each control cycle, the shipborne decision unit will acquire the local tension T in real time. c (t) and the calculated rate of change of tension The comparison is performed against the two preset thresholds mentioned above. This comparison process follows the logic defined in claim 5:

[0074] When the tension T acquired in real time c (t) is lower than the preset tension warning threshold T warn And the absolute value of the rate of change of tension Below the preset critical threshold for the rate of change of tension When the system determines that the mooring system is in a state dominated by normal bow rolling motion, it generates a comparison result to indicate the selection of the first control mode.

[0075] When the tension T acquired in real time c (t) is not lower than the tension warning threshold T warn , or the absolute value of the rate of change of tension Not lower than the critical threshold of the rate of change of tension When the system determines that the mooring system is facing or about to face the risk of impact load, it generates a comparison result to indicate the selection of the second control mode.

[0076] Based on the above comparison results, the system performs a mode selection or switching action. This selection logic can be expressed as:

[0077]

[0078] In the formula, Mode(t) is the control mode selected by the system at time t; T is the rate of change of tension; c (t represents the continuously collected local tension; T) warn The tension warning threshold; This is the critical threshold for the rate of change of tension. Once the judgment condition is met, the system switches to the second control mode immediately, and this switching action is given a higher execution priority. This means that the control commands of the second control mode will override the commands of the first control mode, ensuring that the system responds first to more destructive impact load risks.

[0079] Reference Figure 1 Based on the selected control mode, the target angle of attack of the hydrodynamic surface is determined, and the hydrodynamic surface is controlled to adjust to the target angle of attack to generate the expected hydrodynamic force. This step is the final execution stage of the control method, including target determination and control execution.

[0080] The determination of the target angle of attack is carried out in the shipboard decision unit, and its core is to solve for an optimal wing angle of attack for the currently selected control mode. This process relies on a pre-calibrated hydrodynamic wing model. When the hydrodynamic wing moves relative to the water, it generates lift F. L and resistance F D Its size can be determined by the following formula:

[0081]

[0082] In the formula, F L For lift; F D ρ is the drag force; ρ is the density of seawater; v rel To control the relative velocity between the control device and the surrounding water (measured by an acoustic Doppler current meter on the control device), A f For the effective area of ​​the hydrodynamic wing surface, C L (α) and C D (α) represents the lift coefficient and drag coefficient related to the wing angle of attack α, respectively. The functional relationship between these two coefficients is pre-calibrated through tank tests or hydrodynamic simulations and stored in the shipboard decision unit (e.g., in the form of a lookup table or polynomial).

[0083] The process for determining the target angle of attack is as follows:

[0084] When selecting the first control mode, the objective is to generate a restoring torque that resists the ship's yaw motion, i.e., to generate the maximum lateral damping force. At this point, the shipboard decision unit, based on the acquired ship yaw angular velocity r(t), solves the following optimization problem to determine the target angle of attack. :

[0085]

[0086] In the formula, M z,fin (α) is the bow moment (component along the z-axis of the ship's coordinate system) generated by the hydrodynamic force (combined with the lift and drag generated at an angle of attack of α) on the ship's center of gravity; r(t) is the ship's bow angular velocity; This represents the parameter that maximizes the expression. The goal is to find an angle of attack that maximizes the instantaneous power of the damping moment generated by the wing surface in dissipating the ship's yaw kinetic energy.

[0087] When selecting the second control mode, the objective is to generate a vertical buffering force that weakens the impact load of the anchor chain, i.e., to generate maximum vertical lift. At this point, the shipboard decision unit solves the following optimization problem to determine the target angle of attack. :

[0088]

[0089] In the formula, F fin,Z(α) is the vertical component (positive Z-axis direction) of the total hydrodynamic force generated by the sum of lift and drag when the angle of attack is α in the geodetic coordinate system; This represents the parameter that maximizes the expression. The goal of this formula is to find an angle of attack that maximizes the upward lift of the wing surface to cushion the anchor chain.

[0090] The process of controlling the hydrodynamic surfaces to adjust to the target angle of attack is a closed-loop control execution process. The shipborne decision unit will calculate the target angle of attack ( or This is generated into a digital control command. This control command is encoded and transmitted via the ship's onboard underwater acoustic communication device.

[0091] The underwater control device receives the control command via its built-in underwater acoustic communication unit. The microcontroller inside the device decodes the command and extracts the target angle of attack value. Subsequently, the microcontroller outputs a control signal to its internal actuator (such as a servo motor). The actuator drives the hydrodynamic wing to rotate until the actual angle of attack of the wing matches the target angle of attack in the command. The actual angle of attack of the wing can be measured by an angle encoder linked to the actuator, providing position feedback and ensuring precise control execution.

[0092] Reference Figure 2 One embodiment of the present invention provides a bulk carrier anchoring stability control system based on mechanical optimization. This system is used to execute the control methods described in any of the preceding claims, and its physical implementation is typically distributed between the shipboard and underwater sections, with data and commands interacting between the two via an underwater acoustic communication link.

[0093] Based on its functions, the system includes a status acquisition module, a modal decision-making module, a target determination module, and a control execution module.

[0094] The status acquisition module is responsible for comprehensively collecting the basic data required for system decision-making and control. This module is physically distributed, with one part deployed on the underwater control equipment, including tension sensors for real-time measurement of local tension in the anchor chain; the other part is located on the shipboard system, including data interfaces connected to the ship's GPS, gyrocompass, or inertial navigation unit to acquire the ship's bow roll motion. The status acquisition module also includes a calculation unit for processing the collected local tension time-series data to calculate the rate of change of tension.

[0095] The modal decision module is typically implemented within the shipboard decision unit (e.g., an industrial computer or dedicated controller). It connects to the status acquisition module and receives real-time anchor chain tension and tension change rate from the status acquisition module. Internally, the modal decision module stores preset tension warning thresholds and tension change rate critical thresholds, performs comparisons and judgments, and ultimately outputs a modal selection signal (indicating the selection of the first or second control mode) to specify the current control target.

[0096] The target determination module, typically implemented within the shipboard decision unit, is connected to both the modal decision module and the state acquisition module. This module receives mode selection signals from the modal decision module and real-time bow roll motion data from the state acquisition module. Internally, the target determination module stores hydrodynamic coefficient models of the hydrodynamic surfaces and incorporates different target angle of attack calculation algorithms for the two control modes. Based on the received mode selection signals, it calls the corresponding algorithm, substitutes the real-time ship motion data, and calculates the optimal target angle of attack value.

[0097] The control execution module is a closed-loop control system that spans both the shipboard and underwater sections. Specifically, this module includes a command sending unit, a command receiving unit, and an attitude execution unit.

[0098] The command transmission unit is located within the shipborne decision unit. It is connected to the target determination module and receives the target angle of attack value output by the module. This command transmission unit is responsible for encapsulating this value into a specific digital control command message and converting it into an acoustic signal via the shipborne underwater acoustic communicator, which is then transmitted into the water.

[0099] The command receiving unit is located within the underwater control device. It consists of the underwater part (transducer) of the underwater acoustic communication device and a decoding circuit, used to receive acoustic signals from the shipborne unit and decode them back into digital control commands.

[0100] The attitude execution unit is entirely integrated within the underwater control device. It is connected to the command receiving unit, and its core consists of a microcontroller and a servo actuator. Upon receiving the decoded target angle of attack command, the microcontroller controls the servo actuator to precisely drive the hydrodynamic wing surface rotation. An angle sensor linked to the actuator provides real-time feedback on the actual angle of attack of the wing surface, forming a closed-loop position control system. This ensures that the wing surface ultimately stabilizes at the target angle of attack required by the command, thereby generating the expected hydrodynamic force.

Claims

1. A method for regulating the anchoring stability of bulk carriers based on mechanical optimization, characterized in that, Includes the following steps: S1. Install a control device with controllable hydrodynamic fins on the ship's anchor chain. S2. Real-time acquisition of the tension and tension change rate of the anchor chain, and acquisition of the bow roll motion state of the ship; S3. Based on the comparison results of the tension and the rate of change of tension with a preset threshold, select between a first control mode for suppressing the yaw motion and a second control mode for suppressing the anchor chain impact load; S4. Based on the selected control mode, determine the target angle of attack of the hydrodynamic surface, and control the hydrodynamic surface to adjust to the target angle of attack to generate the expected hydrodynamic force, thereby achieving the control of the ship's anchoring stability.

2. The method for controlling the anchoring stability of bulk carriers based on mechanical optimization according to claim 1, characterized in that, In step S1, the deployment of the control device with controllable hydrodynamic surfaces specifically includes: The control device is fixed to the anchor chain by a universal rotating gripper; The universal rotating gripper axially locks the control device and the anchor chain while allowing the anchor chain to rotate freely around its own axis, thus isolating the influence of the anchor chain torsion on the attitude of the control device.

3. The method for controlling the anchoring stability of bulk carriers based on mechanical optimization according to claim 1, characterized in that, In step S2, obtaining the tension and rate of change of the anchor chain includes: Using tension sensors installed on the control device, the local tension of the anchor chain at the location of the control device is measured in real time; The rate of change of tension is calculated based on the continuous time series data of the local tension.

4. The method for controlling the anchoring stability of bulk carriers based on mechanical optimization according to claim 1, characterized in that, In step S2, obtaining the bow roll motion state of the ship includes: The ship's position, speed, and heading in the geodetic coordinate system are acquired and recorded in real time using its onboard global positioning system, gyrocompass, or inertial navigation unit. Based on the continuous time series data of the heading, the bow roll rate of the ship is calculated, and the position, velocity, heading, and bow roll rate are used together as a characterization of the ship's bow roll motion state.

5. The method for controlling the anchoring stability of bulk carriers based on mechanical optimization according to claim 1, characterized in that, In step S3, the comparison results between the tension and the rate of change of tension and the preset threshold specifically include: When the real-time acquired tension is lower than a preset tension warning threshold, and the absolute value of the tension change rate is lower than a preset tension change rate critical threshold, a comparison result is generated to indicate the selection of the first control mode. When the real-time acquired tension is not lower than the tension warning threshold, or the absolute value of the tension change rate is not lower than the tension change rate critical threshold, a comparison result is generated to indicate the selection of the second control mode.

6. The method for controlling the anchoring stability of bulk carriers based on mechanical optimization according to claim 1, characterized in that, In step S3, the selection between the first control mode and the second control mode specifically includes: When it is determined that the absolute values ​​of the tension and the rate of change of tension are both lower than the corresponding preset thresholds, the current control mode is selected or maintained in the first control mode. When it is determined that at least one of the absolute values ​​of the tension or the rate of change of tension is not lower than the corresponding preset threshold, the current control mode is immediately selected or switched to the second control mode, and a higher execution priority is assigned.

7. The method for controlling the anchoring stability of bulk carriers based on mechanical optimization according to claim 1, characterized in that, In step S4, determining the target angle of attack of the hydrodynamic wing surface specifically includes: When selecting the first control mode, the goal is to generate a restoring torque that resists the bow roll motion of the ship. Based on the bow roll motion state of the ship, the angle of attack that can generate the maximum lateral damping force of the hydrodynamic wing surface is calculated in real time and determined as the target angle of attack. When selecting the second control mode, with the goal of generating a vertical buffering force that weakens the impact load of the anchor chain, the angle of attack that enables the hydrodynamic wing surface to generate the maximum vertical lift is calculated and determined as the target angle of attack.

8. The method for controlling the anchoring stability of bulk carriers based on mechanical optimization according to claim 1, characterized in that, In step S4, adjusting the hydrodynamic surface to the target angle of attack specifically includes: The target angle of attack is generated into a control command, and the control command is sent to the control device via underwater acoustic communication. After receiving the control command, the control device drives the hydrodynamic wing surface to adjust to the target angle of attack through its internal actuator.

9. A bulk carrier anchoring stability control system based on mechanical optimization, wherein the bulk carrier anchoring stability control method based on mechanical optimization according to any one of claims 1-8 is characterized in that, include: The status acquisition module is used to acquire the anchor chain tension measured by the control device deployed on the ship's anchor chain in real time, calculate the tension change rate, and acquire the bow roll motion state of the ship. The modal decision module, connected to the state acquisition module, is used to select between a first control mode for suppressing yaw motion and a second control mode for suppressing anchor chain impact load based on the comparison results of tension and tension change rate with a preset threshold. The target determination module is connected to the modal decision module and the state acquisition module respectively, and is used to determine the target angle of attack of the hydrodynamic surface based on the selected control mode and in combination with the bow roll motion state of the ship. The control execution module is connected to the target determination module. The control execution module is used to generate the target angle of attack into a control command and control the hydrodynamic surfaces in the control device to adjust to the target angle of attack to generate the expected hydrodynamic force.

10. The bulk carrier anchoring stability control system based on mechanical optimization according to claim 9, characterized in that, The control execution module includes: The command sending unit is used to generate the target angle of attack into a control command and send the control command via underwater acoustic communication. An instruction receiving unit is installed within the control device and is used to receive the control instructions via the underwater acoustic communication method. An attitude execution unit, located within the control device, is used to drive the hydrodynamic surface to adjust to the target angle of attack after receiving the control command.

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