A test device and control method for zero-speed roll reduction of a ship

Abstract

This invention relates to an experimental apparatus and control method for reducing roll at zero speed on a ship. The experimental apparatus includes a ship model, a forced roll device, a sensor device, and a fin roll damping device. The forced roll device drives the ship model to produce roll motion. The sensor device monitors the attitude information of the ship model during the roll motion. The control device generates motion decisions for the fin roll damping device through a strategy network. The fin roll damping device flaps to a specified angle and frequency according to the motion decisions generated by the control device. The sensor device monitors the attitude changes of the ship model and the actual flapping angle of the fin roll damping device in real time and feeds it back to the control device. The control device evaluates the effectiveness of the current strategy based on the feedback from the sensor device: if the roll reduction effect meets the requirements, the current strategy is strengthened; otherwise, the strategy network is updated to further optimize the control action of the fin roll damping device. The experimental apparatus and control method are simple in structure and can achieve roll reduction under different sea conditions and dynamic changes in ship roll.

Description

Technical Field

[0001] This invention relates to the field of ship roll reduction technology, specifically to a test device and control method for reducing ship roll at zero speed. Background Technology

[0002] With the development and utilization of marine resources, the safety of ship transportation, marine platform service and maintenance is receiving increasing attention and importance.

[0003] Ships, under the influence of external environmental loads such as wind, waves, and currents, experience six degrees of freedom of rolling motion, including roll, pitch, bow roll, sway, heave, and sway. Rolling motion is characterized by large amplitude, short period, and high acceleration, directly impacting crew comfort and the operational capability of equipment. Severe, large-amplitude rolling can cause capsizing and threaten the ship's stability and buoyancy. While the rolling moment is much smaller than the pitch moment, techniques for reducing ship rolling are feasible and effective. Furthermore, ships in free-floating or anchored states, as well as offshore platforms during installation and operation, are also susceptible to significant rolling motion due to wave action. Although methods such as bilge keels, lifting fins, and anti-roll tanks exist for active or passive control of ship rolling, these techniques have been developed to mitigate the impact of rolling motion. However, traditional lift-type anti-roll fins achieve roll reduction by rotating their spanwise axis to create an angle of attack and utilizing lift at ship speed. However, their amplitude of motion is relatively small, so they lose lift when the ship is at zero speed, significantly weakening their roll reduction capability. Anti-roll tanks have a good roll reduction effect near their resonant frequency, but their roll reduction capability decreases considerably when the wave frequency deviates from their resonant frequency.

[0004] Water tank model testing is a common method for studying the motion performance of ships in waves and roll reduction technologies. By installing roll reduction devices on ship models and conducting experiments in a water tank environment, it is possible to obtain the motion performance of a real ship in waves and test the roll reduction devices.

[0005] However, the roll drive devices in traditional ship model roll reduction test equipment are bulky, complex in structure, and expensive to purchase. In addition, traditional roll reduction control algorithms and strategies also have certain shortcomings in roll reduction efficiency, making it difficult to achieve roll reduction under different sea conditions and dynamic changes in ship roll. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a test device and control method for reducing ship roll at zero speed. The device has a simple structure and can reduce roll under different sea conditions and dynamic changes in ship roll.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A test device for reducing roll at zero speed of a ship includes a ship model and a control device. The ship model is equipped with a forced roll device, a sensor device and a fin roll reduction device.

[0009] The forced roll device is used to drive the model ship to produce a rolling motion.

[0010] The sensor device is used to monitor the attitude information of the model boat during the rolling motion, including the rolling angle, rolling angular velocity and rolling acceleration, and send it to the control device.

[0011] The control device is used to generate action decisions for the fin roll reduction device through a strategy network based on the received ship model attitude information.

[0012] The fin anti-roll device flaps to a specified angle and frequency based on the motion decision generated by the control device;

[0013] The sensor device monitors the attitude changes of the model boat and the actual flapping angle of the fin roll reduction device in real time and feeds it back to the control device. The control device evaluates the effectiveness of the current strategy based on the feedback from the sensor device: if the roll reduction effect meets the requirements, the current strategy is strengthened; otherwise, the strategy network is updated to further optimize the control action of the fin roll reduction device.

[0014] Furthermore, the forced roll device includes a stepper motor, a first transmission device, and a slider, with the slider slidably connected to the ship model; the stepper motor is fixed to the ship model and connected to the first transmission device, which is connected to the slider and is used to drive the slider to make lateral movements on the ship model.

[0015] Furthermore, the first transmission device includes a belt, a pulley, and a guide wheel. The pulley and the guide wheel are respectively hinged to the ship model. The belt is wound around the pulley and the guide wheel. A stepper motor is driven and connected to the pulley. The slider is fixed to the belt.

[0016] Furthermore, the first transmission device also includes a slide rail, which is fixed to the ship model, and the slider is nested on the slide rail and slidably connected to the slide rail.

[0017] Furthermore, the sensor device includes an accelerometer and a gyroscope. The accelerometer is located on the side of the ship model where it is placed and is used to measure the roll acceleration of the ship model. The gyroscope is located at the mid-longitudinal section of the ship model and is used to measure the roll angle and roll angular velocity of the ship model.

[0018] Furthermore, the fin anti-roll device includes a fin drive motor, a second transmission device, and a flapping fin. The fin drive motor is fixed to the boat model and connected to the second transmission device, and the second transmission device is connected to the flapping fin to drive the flapping fin to flap repeatedly.

[0019] Furthermore, the second transmission device includes a right-angle gearbox, the drive shaft of the fin drive motor is vertically arranged, the right-angle gearbox is located below the fin drive motor, the right-angle gearbox includes a linked vertical shaft and a horizontal shaft, the vertical shaft of the right-angle gearbox is connected to the drive shaft of the fin drive motor, and the flapping fin is connected to the horizontal shaft of the right-angle gearbox.

[0020] Furthermore, two sets of fin anti-roll devices are provided, with the two sets of fin anti-roll devices respectively located on the left and right sides of the ship model.

[0021] Furthermore, the control device is a PPO algorithm intelligent agent.

[0022] A control method for a test device for reducing roll at zero speed on a ship includes the following steps:

[0023] The forced rolling device drives the ship model to produce rolling motion;

[0024] The sensor device monitors the attitude information of the model boat during the rolling motion, including the rolling angle, rolling angular velocity and rolling acceleration, and sends it to the control device.

[0025] The control device generates motion decisions for the fin roll reduction device through a strategy network based on the received ship model attitude information.

[0026] The fin anti-roll device flaps to a specified angle and frequency based on the motion decision generated by the control device;

[0027] The sensor device monitors the attitude changes of the model boat and the actual flapping angle of the fin roll reduction device in real time and feeds it back to the control device. The control device evaluates the effectiveness of the current strategy based on the feedback from the sensor device: if the roll reduction effect meets the requirements, the current strategy is strengthened; otherwise, the strategy network is updated to further optimize the control action of the fin roll reduction device.

[0028] In summary, the present invention has the following advantages:

[0029] (1) The flapping fin anti-roll device in this invention uses bionic control by imitating the flapping of fish pectoral fins, which can generate a large anti-roll torque for ships at zero or low speeds, thereby achieving the purpose of reducing ship roll.

[0030] (2) The present invention uses artificial intelligence methods to learn, train and control the motion logic of the fin anti-roll device. Through artificial intelligence algorithm based on proximal strategy optimization (PPO) and using ship model roll information as feedback, it autonomously learns the anti-roll motion trajectory of flapping fins to realize ship anti-roll control and adapts to ship anti-roll under different roll frequencies and roll amplitudes.

[0031] (3) By introducing a forced roll device, this invention establishes a low-cost ship roll excitation method that can effectively simulate the ship roll motion caused by actual waves. The artificial intelligence roll reduction model trained in the forced roll environment can be directly applied to roll reduction control in actual wave environments without retraining. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the ship model.

[0033] Figure 2(a) is a schematic diagram of the forced swaying device.

[0034] Figure 2(b) is a structural schematic diagram of the forced roll device from another perspective.

[0035] Figure 3 This is a schematic diagram of the fin anti-roll device.

[0036] Figure 4 This is a flowchart of the PPO algorithm based on a flapping fin anti-roll device.

[0037] In the picture:

[0038] 1 is a ship model;

[0039] 2 is the forced lateral rocking device; 2-1 is the stepper motor; 2-2 is the slider; 2-3 is the slide rail; 2-4 is the belt; 2-5 is the pulley; 2-6 is the guide wheel; 2-7 is the base;

[0040] 3 is the fin anti-roll device; 3-1 is the fin drive motor; 3-2 is the connecting shaft; 3-3 is the waterproof bushing; 3-4 is the gearbox base; 3-5 is the right-angle gearbox; 3-6 is the flapping fin;

[0041] 4 is a gyroscope;

[0042] 5 represents the accelerometer. Detailed Implementation

[0043] The present invention will now be described in further detail.

[0044] like Figure 1 , Figure 4 As shown, a test device for reducing roll at zero speed of a ship includes a ship model 1 and a control device. In this embodiment, the control device is a PPO algorithm intelligent agent.

[0045] The ship model 1 is equipped with a forced roll device 2, a sensor device, and a fin anti-roll device 3;

[0046] The forced rolling device 2 is used to drive the ship model 1 to produce a rolling motion;

[0047] The sensor device is used to monitor the attitude information of the ship model 1 during the rolling motion, including the rolling angle, rolling angular velocity and rolling acceleration, and send it to the control device.

[0048] The control device is used to generate action decisions for the fin roll reduction device 3 through a strategy network based on the received attitude information of the ship model 1.

[0049] The fin anti-roll device 3 flaps to a specified angle and frequency based on the motion decision generated by the control device;

[0050] The sensor device monitors the attitude changes of the boat model 1 and the actual flapping angle of the fin anti-roll device 3 in real time and feeds it back to the control device. The control device evaluates the effectiveness of the current strategy based on the feedback from the sensor device: if the anti-roll effect meets the requirements, the current strategy is strengthened; otherwise, the strategy network is updated to further optimize the control action of the fin anti-roll device 3.

[0051] Specifically, the ship model 1 includes a hull shell, ballast blocks, and constraint connection devices. The hull shell is machined according to the hull line drawing of the target ship type, and its shape is geometrically similar to the target ship type. The interior of the hull shell is hollow, used to house other equipment. The ballast blocks are fixed inside the hull shell and are used to adjust the buoyancy of the model, ensuring that its center of gravity, weight distribution, and moment of inertia meet target values. The constraint connection devices are used to connect the ship model 1 to the tank trailer, etc., thereby preventing the ship model 1 from drifting and constraining the ship model 1's degrees of freedom such as pitch, sway, and bow roll as needed, improving the accuracy of the test.

[0052] The forced roll device 2 is installed at the rear of the midship to simulate the effect of waves and cause the model ship 1 to roll. The sensor device is installed on the deck in front of the midship to measure the roll angle, roll acceleration and other signals of the model ship 1. The fin anti-roll device 3 is installed at the midship position and has an opening at the bilge position to extend the flapping fins 3-6 of the fin anti-roll device 3 from the inside of the hull to the outside of the hull.

[0053] As shown in Figures 2(a) and 2(b), specifically, the forced rolling device 2 includes a stepper motor 2-1, a first transmission device, and a slider 2-2. The slider 2-2 is slidably connected to the ship model 1. The stepper motor 2-1 is fixed to the ship model 1 and connected to the first transmission device. The first transmission device is connected to the slider 2-2 and is used to drive the slider 2-2 to make lateral movements on the ship model 1. The first transmission device includes a belt 2-4, a pulley 2-5, and a guide wheel 2-6. The pulley 2-5 and the guide wheel 2-6 are respectively hinged to the ship model 1. The belt 2-4 is wound around the pulley 2-5 and the guide wheel 2-6. The stepper motor 2-1 is driven and connected to the pulley 2-5, and the slider 2-2 is fixed to the belt 2-4.

[0054] In this embodiment, the forced rolling device 2 also includes a base 2-7, which is fixed on the ship model 1. A stepper motor 2-1 is fixed to the bottom of the base 2-7, and the shaft of the stepper motor 2-1 is fixedly connected to the pulley 2-5. Two guide wheels 2-6 are respectively installed on the left and right sides of the base 2-7 by cylindrical pins and can rotate freely. There are a total of 4 guide wheels 2-6. The belt 2-4 is sleeved on the outer ring of the triangle formed by the pulley 2-5 and the two guide wheels 2-6, and contacts the outer ring of the belt 2-4 through the other two guide wheels 2-6 installed on the base 2-7, which serves to tension the belt 2-4. The slide rail 2-3 is installed above the base 2-7, and the slider 2-2 is nested on the slide rail 2-3 and can slide left and right. The slider 2-2 is fixedly connected to the belt 2-4 at one point by bolts. The rotation of the stepper motor 2-1 can be converted into the translation of the slider 2-2, and the forced rolling motion of the ship model 1 is achieved by the translation of the slider 2-2.

[0055] The sensor device includes an accelerometer 5 and a gyroscope 4. The accelerometer 5 is placed on the port or starboard side of the deck to measure the roll acceleration at that location; the gyroscope 4 is placed in the longitudinal section of the ship model 1 to monitor information such as the ship's roll angle and roll rate.

[0056] like Figure 3 As shown, the fin anti-roll device 3 is provided in two sets. The fin anti-roll device 3 includes a fin drive motor 3-1, a second transmission device, and a flapping fin 3-6. The second transmission device includes a connecting shaft 3-2, a waterproof bushing 3-3, a gearbox base 3-4, and a right-angle gearbox 3-5.

[0057] Two fin drive motors 3-1 are fixedly connected to the left and right sides of the ship, with the drive shafts of the fin drive motors 3-1 in a vertical direction. Two right-angle gearboxes 3-5 are respectively installed on both sides of the gearbox base 3-4 in the outer groove of the middle section of the ship model 1, positioned directly below the fin drive motors 3-1. The vertical axis of the right-angle gearboxes 3-5 is connected to the drive shaft of the fin drive motors 3-1 via a connecting shaft 3-2, which passes through the inside and outside of the hull via a waterproof bushing 3-3. The rotation shaft of the flapping fin 3-6 is fixedly connected to the horizontal axis of the right-angle gearboxes 3-5. The rotation of the shaft of the fin drive motor 3-1 can be converted into the flapping of the flapping fin 3-6.

[0058] like Figure 4 As shown, a control method for a test device for reducing roll at zero speed on a ship includes the following steps:

[0059] The forced rolling device 2 drives the ship model 1 to produce a rolling motion;

[0060] Gyroscope 4 and accelerometer 5 monitor the ship's attitude information, including key information such as roll angle, roll rate and acceleration, and convert this information into state signals and input them into the PPO algorithm agent;

[0061] Based on the received ship motion attitude information and the actual environmental conditions, the PPO algorithm agent generates the flapping angle and motion decisions for the fin roll reduction device 3 through a policy network. At this point, the PPO algorithm uses its policy function to determine the optimal motion angle of the fin roll reduction device 3 to maximize the roll reduction effect.

[0062] The diving servo is driven to rotate according to the angle signal of the fin anti-roll device 3 output by the PPO algorithm intelligent agent, so as to move the flapping fins 3-6 to the specified angle and frequency.

[0063] After the flapping fins 3-6 move, gyroscope 4 monitors the ship's attitude changes (the reduction in the ship's roll angle) and the actual flapping angle of the flapping fins 3-6 in real time, and returns the feedback signal to the PPO algorithm agent. The PPO algorithm agent evaluates the effectiveness of the current policy through the reward mechanism in the evaluation function of reinforcement learning: if the roll reduction effect is ideal, the agent strengthens the current policy; if the effect is poor, the PPO algorithm agent further optimizes the control action of the flapping fins 3-6 by updating the policy network.

[0064] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A test device for reducing roll at zero speed on a ship, characterized in that: It includes a ship model and a control device. The control device is a PPO algorithm intelligent agent. The ship model is equipped with a forced roll device, a sensor device, and a fin roll reduction device. The forced rolling device is used to drive the ship model to produce a rolling motion. The sensor device is used to monitor the attitude information of the model boat during the rolling motion, including the rolling angle, rolling angular velocity and rolling acceleration, and send it to the control device. The control device is used to generate action decisions for the fin roll reduction device through a strategy network based on the received ship model attitude information. The fin anti-roll device flaps to a specified angle and frequency based on the motion decision generated by the control device. The sensor device monitors the attitude changes of the model boat and the actual flapping angle of the fin anti-roll device in real time and feeds it back to the control device. The control device evaluates the effectiveness of the current strategy based on the feedback from the sensor device through the reward mechanism in the evaluation function of reinforcement learning: if the anti-roll effect meets the requirements, the parameters of the current strategy network are strengthened based on the reward mechanism; otherwise, the strategy network is updated through the PPO algorithm to further optimize the flapping angle and frequency of the fin anti-roll device.

2. The experimental apparatus according to claim 1, characterized in that: The forced roll device includes a stepper motor, a first transmission device, and a slider, with the slider slidably connected to the ship model; the stepper motor is fixed to the ship model and connected to the first transmission device, which is connected to the slider and is used to drive the slider to make lateral movements on the ship model.

3. The test apparatus according to claim 1, characterized in that: The first transmission device includes a belt, a pulley, and a guide wheel. The pulley and guide wheel are respectively hinged to the ship model. The belt is wound around the pulley and guide wheel. A stepper motor is connected to the pulley for driving. The slider is fixed to the belt.

4. The test apparatus according to claim 3, characterized in that: The first transmission device also includes a slide rail, which is fixed to the ship model, and a slider is nested on the slide rail and slidably connected to the slide rail.

5. The test apparatus according to claim 1, characterized in that: The sensor device includes an accelerometer and a gyroscope. The accelerometer is located on the side of the ship model to measure the roll acceleration of the ship model. The gyroscope is located at the mid-longitudinal section of the ship model to measure the roll angle and roll angular velocity of the ship model.

6. The test apparatus according to claim 1, characterized in that: The fin anti-roll device includes a fin drive motor, a second transmission device, and a flapping fin. The fin drive motor is fixed to the boat model and connected to the second transmission device. The second transmission device is connected to the flapping fin and is used to drive the flapping fin to flap repeatedly.

7. The test apparatus according to claim 6, characterized in that: The second transmission device includes a right-angle gearbox, the drive shaft of the fin drive motor is vertically arranged, the right-angle gearbox is located below the fin drive motor, the right-angle gearbox includes a linked vertical shaft and a horizontal shaft, the vertical shaft of the right-angle gearbox is connected to the drive shaft of the fin drive motor, and the flapping fin is connected to the horizontal shaft of the right-angle gearbox.

8. The test apparatus according to claim 1, characterized in that: Two sets of fin damping devices are provided, with the two sets of fin damping devices located on the left and right sides of the ship model respectively.

9. The control method of the test device for reducing roll at zero speed of a ship according to any one of claims 1-8, characterized in that: Includes the following steps, The forced rolling device drives the ship model to produce rolling motion; The sensor device monitors the attitude information of the ship model during the roll motion, including the roll angle, roll angular velocity and roll acceleration, and sends it to the control device, which is a PPO algorithm intelligent agent. The control device generates motion decisions for the fin roll reduction device through a strategy network based on the received ship model attitude information. The fin anti-roll device flaps to a specified angle and frequency based on the motion decision generated by the control device; The sensor device monitors the attitude changes of the model boat and the actual flapping angle of the fin anti-roll device in real time and feeds it back to the control device. Based on the feedback from the sensor device, the control device evaluates the effectiveness of the current strategy through the reward mechanism in the evaluation function of reinforcement learning: if the anti-roll effect meets the requirements, the parameters of the current strategy network are strengthened based on the reward mechanism; otherwise, the strategy network is updated through the PPO algorithm to further optimize the flapping angle and frequency of the fin anti-roll device.

Images