Autonomous berthing method for under-actuated ship based on berth adapter
By adjusting the ship's behavior by using the magnitude of the berth hook contact force in the berth adapter, the shortcomings of ship berth control in the complex marine environment in the prior art are solved, and stable and efficient berthing in complex environments are achieved.
Patent Information
- Application Number
- CN202411247964.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-06
- Publication Date
- 2025-01-14
AI Technical Summary
The design of existing berth adapters fails to fully consider the dynamic changes of the complex marine environment and lacks effective real-time control strategies, resulting in the problems of heading deviation and instability in the berthing process of under-driven ships.
By obtaining the berth area, calculating the optimal navigation path, and adjusting the ship's behavior by using the magnitude of the berth hook contact force during the berthing process, including adjustment of the driving force magnitude and direction, ensuring that the hull is parallel to the dock and achieving independent berthing.
It provides effective real-time control strategies in complex marine environments, improves the stability and efficiency of ship berthing, and reduces the requirements for captain operation level.
Smart Images
Figure CN119310987A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of ship berthing, and in particular to an autonomous berthing method for an under-actuated ship based on a berth adapter. Background Art
[0002] Due to the lack of lateral propulsion capability, the motion control of underactuated ships is highly nonlinear and uncertain, and is more prone to heading deviation and attitude instability, especially when affected by complex marine environments such as crosswinds and side currents. Traditional ship berthing methods usually rely on manual operations by experienced captains, which is not only inefficient but also requires a high level of operation from the captain.
[0003] In order to solve these problems, in recent years, many studies have been devoted to enhancing the berthing ability of ships through automation and intelligent means. For example, some studies have adopted advanced control algorithms such as fuzzy control, neural networks, and model predictive control to improve the autonomous control performance of underactuated ships. However, these methods still have some limitations in practical applications, such as slow system response, poor adaptability to environmental changes, and high computational costs caused by algorithm complexity. Berth adapters, as an emerging auxiliary equipment, can alleviate the difficulty of maneuvering underactuated ships to a certain extent. Through the optimization design of mechanical structure, berth adapters can provide additional support and stability during the berthing process of ships. However, the current design of berth adapters has not fully taken into account the dynamic changes of complex marine environments and lacks effective real-time control strategies. Summary of the invention
[0004] In view of this, the purpose of the present invention is to propose an autonomous berthing method for an under-actuated ship based on a berth adapter, so as to solve the problem that the current berth adapter design has not fully considered the dynamic changes of the complex marine environment and lacks an effective real-time control strategy.
[0005] Based on the above objectives, the present invention provides an autonomous berthing method for an under-actuated ship based on a berth adapter, comprising:
[0006] Transitional navigation phase: obtaining the berth area, calculating the optimal navigation path from the current position of the ship to the berth area, and the ship sails along the optimal navigation path;
[0007] Berthing preparation stage: When the ship reaches the predetermined distance of the berth area, it obtains the predetermined turning point in the berth area. When the ship is at the specified radius r of the turning point turning When the vessel is within the berth, it enters the turning state and starts to turn until the vessel points to the berth receiver;
[0008] Berthing stage: When |ψ-berth receiver direction|<1, where ψ is the ship's heading angle, the ship stops turning and sails towards the berth receiver. When the berthing hook on the ship just docks with the berthing receiver on the dock, or the berthing hook first contacts the dock and then slides along the dock into the berthing receiver on the dock, the ship enters the docking rotation state. In the docking rotation state, the magnitude of the contact force F on the berthing hook is li , adjust the behavior of the ship during the berthing process so that the hull is parallel to the dock and complete the berthing of the ship.
[0009] Optionally, the contact force F on the berth hook is li , adjusting the behavior of the ship during berthing includes:
[0010] The F li Based on the compression amount δ of the berth hook, the δ=|r hitch -|d ai ||
[0011] where r hitch is the radius of the berth hook, |d ai | is the distance between the berth hook and the contact surface;
[0012] Calculate the contact angle α between the berth hook and the berth receiver cf =α li -ψ;
[0013] where α li is the azimuth angle of the berth receiver, ψ is the heading angle of the ship (NED coordinate system);
[0014] Using the contact angle α cf , the contact force F li Decomposed into components in the hull coordinate system:
[0015]
[0016] Based on the contact force F li The component in the hull coordinate system adjusts the working behavior of the driving force during the berthing process of the ship.
[0017] Optionally, the specified radius
[0018] Among them, "vessel" and "turning" represent the coordinate position of the vessel and the coordinate position of the turning point respectively.
[0019] Optionally, the heading angle in the transition navigation phase adopts the LOS algorithm, and the heading angle of the ship in the berthing preparation phase is the angle x between the ship and the turning point. ref =atan2(turning y-vessel y ,turning x -vessel x ), the berthing stage heading angle is the angle between the berthing hook and the berthing receiver:
[0020] χ ref =atan2(docking y -hitch y ,docking x -hitch x )
[0021] Where docking and hitch are the coordinate positions of the berth receiver and berth hook in the NED coordinate system.
[0022] Optionally, the principle of the LOS algorithm is:
[0023]
[0024] In the formula represents waypoints, π p Calculate the track angle for two points, is the lateral distance between the ship and the route, Where Δ is the specified foresight distance parameter, χ d is the expected heading angle, and the relationship between the heading angle χ and the heading angle ψ is:
[0025] χ=ψ+β c
[0026] in u and v represent the longitudinal and lateral velocities of the ship respectively.
[0027] Optionally, the vessel includes radar and sonar systems, which are used to detect the surrounding environment, identify potential obstacles, and provide data for updating the navigation route.
[0028] When the method is used to berth a ship, the method first goes through a transitional navigation phase, in which the berthing area is first obtained, the optimal navigation path from the current position of the ship to the berthing area is calculated, and then the ship sails along the optimal navigation path, and then enters the berthing preparation phase, in which when the ship reaches a predetermined distance from the berthing area, a predetermined turning point in the berthing area is obtained, and when the ship is at a specified radius r of the turning point, the ship is turningWhen the ship enters the turning state, it starts to rotate until it points to the berth receiver, and finally enters the berthing stage. When |ψ-berth receiver direction|<1, where ψ is the ship's heading angle, the ship stops rotating and sails towards the berth receiver. When the berthing hook on the ship just docks with the berthing receiver on the dock, or the berthing hook first contacts the dock and then slides along the dock into the berthing receiver on the dock, the ship enters the docking rotation state. In the docking rotation state, the magnitude of the contact force F on the berthing hook is li , adjust the behavior of the ship during the berthing process so that the hull is parallel to the dock and complete the berthing of the ship.
[0029] From the above, it can be seen that the contact force F li To adjust the behavior of the ship during the berthing process. The behavior of the ship during the berthing process mainly includes the adjustment of the size and direction of the ship's driving force. When the marine environment changes, the size of the contact force F li When the change occurs, the behavior of the ship during the berthing process also changes accordingly, thus providing a strategy for implementing control. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0031] Figure 1 It is a schematic diagram of a ship from a transitional sailing phase to a berthing phase according to an embodiment of the present invention. DETAILED DESCRIPTION
[0032] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.
[0033] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0034] like Figure 1 As shown, an autonomous berthing method for an under-actuated ship based on a berth adapter comprises:
[0035] Transitional navigation phase: obtaining the berth area, calculating the optimal navigation path from the current position of the ship to the berth area, and the ship sails along the optimal navigation path;
[0036] Berthing preparation stage: When the ship reaches the predetermined distance of the berth area, it obtains the predetermined turning point in the berth area. When the ship is at the specified radius r of the turning point turning When the vessel is within the berth, it enters the turning state and starts to turn until the vessel points to the berth receiver;
[0037] Berthing stage: When |ψ-berth receiver direction|<1, where ψ is the ship's heading angle, the ship stops turning and sails towards the berth receiver. When the berthing hook on the ship just docks with the berthing receiver on the dock, or the berthing hook first contacts the dock and then slides along the dock into the berthing receiver on the dock, the ship enters the docking rotation state. In the docking rotation state, the magnitude of the contact force F on the berthing hook is li , adjust the behavior of the ship during the berthing process so that the hull is parallel to the dock and complete the berthing of the ship.
[0038] When the method is used to berth a ship, the method first goes through a transitional navigation phase, in which the berthing area is first obtained, the optimal navigation path from the current position of the ship to the berthing area is calculated, and then the ship sails along the optimal navigation path, and then enters the berthing preparation phase, in which when the ship reaches a predetermined distance from the berthing area, a predetermined turning point in the berthing area is obtained, and when the ship is at a specified radius r of the turning point, the ship is turningWhen the ship enters the turning state, it starts to rotate until it points to the berth receiver, and finally enters the berthing stage. When |ψ-berth receiver direction|<1, where ψ is the ship's heading angle, the ship stops rotating and sails towards the berth receiver. When the berthing hook on the ship just docks with the berthing receiver on the dock, or the berthing hook first contacts the dock and then slides along the dock into the berthing receiver on the dock, the ship enters the docking rotation state. In the docking rotation state, the magnitude of the contact force F on the berthing hook is li , adjust the behavior of the ship during the berthing process so that the hull is parallel to the dock and complete the berthing of the ship.
[0039] From the above, it can be seen that the contact force F li To adjust the behavior of the ship during the berthing process. The behavior of the ship during the berthing process mainly includes the adjustment of the size and direction of the ship's driving force. When the marine environment changes, the size of the contact force F li When the change occurs, the behavior of the ship during the berthing process also changes accordingly, thus providing a strategy for implementing control.
[0040] In some embodiments, the surface vessel is capable of moving in six degrees of freedom, namely surge, sway, heave, roll, pitch, and yaw. Due to the stability of heave, roll, and pitch due to its ship structure, the equations of these degrees of freedom can be eliminated to reduce the complexity of the equations. First, heave can be ignored due to the stable buoyancy and lighter weight. Due to its small size, rolling and pitching motions can also be ignored. Therefore, the three-degree-of-freedom motion model of the underactuated surface vessel can be expressed as follows:
[0041] Kinematics:
[0042] where η = [xy ψ] T Respectively represent the longitudinal position, lateral position and heading angle. v = [uvr] T They represent the longitudinal velocity, lateral velocity and heading angular velocity of the ship respectively. The transformation matrix J(η) can be defined as:
[0043]
[0044] dynamics:
[0045] In the formula
[0046] Where M represents the mass matrix. C(v), D(v)) represents the Coriolis matrix, the centripetal matrix, and the drag matrix. τ=[τ x 0 τ N ] TThe control input representing the driving force of the unmanned boat.
[0047] Expanding the above kinematics and dynamics, the motion model of the ship can be obtained as follows:
[0048]
[0049] The contact force F of the berth hook is based on li , adjusting the behavior of the ship during berthing includes:
[0050] The F li Based on the compression amount δ of the berth hook, the δ=|r hitch -|d ai ||, F li The specific relationship between and δ can be obtained by summarizing multiple sets of experimental data;
[0051] where r hitch is the radius of the berth hook, |d ai | is the distance between the berth hook and the contact surface;
[0052] Calculate the contact angle α between the berth hook and the berth receiver cf =α li -ψ;
[0053] where α li is the azimuth angle of the berth receiver, ψ is the heading angle of the ship (NED coordinate system);
[0054] Using the contact angle α cf , the contact force F li Decomposed into components in the hull coordinate system:
[0055]
[0056] Based on the contact force F li The component in the hull coordinate system adjusts the working behavior of the driving force during the berthing process. For example: through the contact force F li The magnitude and direction of the component in the hull coordinate system are used to determine whether the berth hook touches the dock shore. If so, τ is applied. N =0N, τ x =10N, that is, no yaw moment is applied, only propulsion force is applied. When the berth hook enters the berth receiver, it can also be judged according to the magnitude and direction of the force on the berth hook, because the direction of the berth receiver is different from the direction of the dock shore, so it can be judged whether to enter the docking state. In the docking state, only the yaw moment τ can be applied. N .
[0057] In some embodiments, the specified radius
[0058] Among them, "vessel" and "turning" represent the coordinate position of the vessel and the coordinate position of the turning point respectively.
[0059] In some embodiments, the heading angle of the transition navigation phase adopts the LOS algorithm, and the heading angle of the ship in the berthing preparation phase is the angle x between the ship and the turning point. ref =atan2(turning y -vessel y ,turning x -vessel x ), the berthing stage heading angle is the angle between the berthing hook and the berthing receiver:
[0060] χ ref =atan2(docking y -hitch y ,docking x -hitch x )
[0061] Where docking and hitch are the coordinate positions of the berth receiver and berth hook in the NED coordinate system.
[0062] The heading guidance in different states in heading planning is different. In the transition navigation stage, the path tracking adopts the LOS algorithm. In the berthing preparation stage, in order to ensure direct arrival at the turning point, the angle between the ship and the turning point is used as the required heading angle:
[0063] χ ref =atan2(turning y -vessel y ,turning x -vessel x )
[0064] During the approach docking phase, the course planning does not use the LOS algorithm. That is, using the LOS algorithm may cause the vessel to take unnecessary control actions to minimize the lateral distance error of the vessel from the course. The LOS algorithm is mainly used for path following, ensuring that the vessel remains on the correct path between two waypoints. However, in this method, the focus is more on driving towards the waypoint itself rather than strictly adhering to a direct path. Instead, in order to determine the heading, during the berthing phase, the angle between the berthing hook and the berthing receiver is directly used:
[0065] χ ref =atan2(docking y -hitch y ,dockingx -hitch x )
[0066] In some embodiments, the principle of the LOS algorithm is:
[0067]
[0068] In the formula represents waypoints, π p Calculate the track angle for two points, is the lateral distance between the ship and the route, Where Δ is the specified foresight distance parameter, χ d is the expected heading angle, and the relationship between the heading angle χ and the heading angle ψ is:
[0069] χ=ψ+β c
[0070] in u and v represent the longitudinal and lateral velocities of the ship respectively.
[0071] In some embodiments, the vessel includes radar and sonar systems for detecting the surrounding environment, identifying potential obstacles, and providing data for updating the navigation route.
[0072] It should be understood by those skilled in the art that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or in different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the above aspects of the present invention, which are not provided in detail for the sake of simplicity.
[0073] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. An autonomous berthing method for an underactuated ship based on a berth adapter, characterized in that: include: Transitional navigation phase: obtaining the berth area, calculating the optimal navigation path from the current position of the ship to the berth area, and the ship sails along the optimal navigation path; Berthing preparation stage: When the ship reaches the predetermined distance of the berth area, it obtains the predetermined turning point in the berth area. When the ship is at the specified radius r of the turning point turning When the vessel is within the berth, it enters the turning state and starts to turn until the vessel points to the berth receiver; Berthing stage: When |ψ-berth receiver direction|<1, where ψ is the ship's heading angle, the ship stops turning and sails towards the berth receiver. When the berthing hook on the ship just docks with the berthing receiver on the dock, or the berthing hook first contacts the dock and then slides along the dock into the berthing receiver on the dock, the ship enters the docking rotation state. In the docking rotation state, the magnitude of the contact force F on the berthing hook is li , adjust the behavior of the ship during the berthing process so that the hull is parallel to the dock and complete the berthing of the ship.
2. The autonomous berthing method for an underactuated ship based on a berth adapter according to claim 1, characterized in that: The contact force F of the berth hook is based on li , adjusting the behavior of the ship during berthing includes: The F li Based on the compression amount δ of the berth hook, the δ=|r hitch -|d ai || where r hitch is the radius of the berth hook, |d ai | is the distance between the berth hook and the contact surface; Calculate the contact angle α between the berth hook and the berth receiver cf =α li -ψ; where α li is the azimuth angle of the berth receiver, ψ is the heading angle of the ship (NED coordinate system); Using the contact angle α cf , the contact force F li Decomposed into components in the hull coordinate system: Based on the contact force F li The component in the hull coordinate system adjusts the working behavior of the driving force during the berthing process of the ship.
3. The autonomous berthing method for an under-actuated ship based on a berth adapter according to claim 1, characterized in that: The specified radius Among them, "vessel" and "turning" represent the coordinate position of the vessel and the coordinate position of the turning point respectively.
4. The autonomous berthing method for an under-actuated ship based on a berth adapter according to claim 1, characterized in that: The heading angle in the transitional navigation phase adopts the LOS algorithm, and the heading angle of the ship in the berthing preparation phase is the angle x between the ship and the turning point. re f = atan2(turning y -vessel y ,turning x -vessel x ), the berthing stage heading angle is the angle between the berthing hook and the berthing receiver: χ ref =atan2(docking y -hitch y ,docking x -hitch x ) Where docking and hitch are the coordinate positions of the berth receiver and berth hook in the NED coordinate system.
5. The autonomous berthing method for an under-actuated ship based on a berth adapter according to claim 4, characterized in that: The principle of the LOS algorithm is: In the formula represents waypoint, π p Calculate the track angle for two points, is the lateral distance between the ship and the route, Where Δ is the specified foresight distance parameter, χ d is the expected heading angle, and the relationship between the heading angle χ and the heading angle ψ is: x=ψ+β c in u and v represent the longitudinal and lateral velocities of the ship respectively.
6. The autonomous berthing method for an under-actuated ship based on a berth adapter according to claim 1, characterized in that: The vessel includes radar and sonar systems, which are used to detect the surrounding environment, identify potential obstacles, and provide data for updating the navigation route.