Automatic ship mooring device based on parallel mechanism

Abstract

The automatic ship mooring device based on the parallel mechanism comprises a plurality of sets of mooring working units arranged in the length direction of a ship body, and each set of mooring working unit comprises a base fixedly installed on a wharf and a suction cup connecting mechanism used for being connected with a ship in an adsorption mode. Four parallel motion branch chains are connected between the base and the suction cup connecting mechanism, so that the suction cup connecting mechanism has the freedom degrees of three-dimensional movement and rotation around one shaft, and the four parallel motion branch chains are subjected to cooperative telescopic control through an arranged controller to achieve mooring buffering; the four parallel motion branch chains comprise a first UPU branch chain, a second UPU branch chain, a first SPU branch chain and a second SPU branch chain. Compared with the prior art, the method can actively adapt to and compensate the complex motion of the ship, and has the advantages of low control difficulty, high control precision and high reliability.

Description

Technical Field

[0001] This invention relates to the field of ship mooring technology, and in particular to an automatic ship mooring device based on a parallel mechanism. Background Technology

[0002] Ship mooring is a crucial part of ship navigation operations. It is mainly used for scenarios such as ships entering and leaving ports, berthing, and loading and unloading cargo. Its core is to use mooring devices to securely restrain ships to the dock, buoys, or seabed anchoring structures, preventing ships from drifting or colliding due to environmental disturbances such as wind, waves, and currents, and ensuring the safety of ships, crew members, and port facilities.

[0003] Traditional ship mooring primarily relies on passive cushioning devices such as nylon cables and rubber fenders. These methods have significant limitations: cables have limited elastic deformation under high tensile forces and are prone to fatigue breakage; rubber fenders mainly absorb energy through their own deformation, resulting in low cushioning efficiency and an inability to actively adapt to complex weather and sea conditions. Furthermore, the berthing process is time-consuming and poses safety hazards due to the ship's piloting skills and coordination with shore personnel. With the increasing size of ships and the automation of ports, traditional passive and sluggish mooring methods can no longer meet the demands for efficient and safe operations, especially under windy and wave conditions, where the risk of severe collisions and friction between ships and the dock remains prominent.

[0004] Most of the actuators in commercially available mooring devices are serial mechanisms. Serial mechanisms consist of a series of links connected end to end via joints. They are characterized by a large working space but also by an error accumulation effect. The accuracy of the end effector will be amplified step by step due to the gaps and deformations of each joint, resulting in insufficient rigidity when subjected to huge mooring reaction forces, which can easily lead to vibration and positioning deviations.

[0005] A search revealed that Chinese invention patent application CN107521623A discloses a five-DOF variable-cell multi-purpose ship mooring device. This mooring device utilizes parallel mooring supports to drive elliptical suction cup seats and magnetic suction cups to extend outward from the hull. After energization, the electromagnetic force generated by the magnetic suction cups connects the main ship hull to the dock to achieve mooring. However, because the parallel mooring supports use an RPUR chain with four kinematic pairs, the joint locking mode is switched by switching the power on and off of an undriven electromagnetic brake to change the degree of freedom of the mechanism to meet mooring requirements. However, in its two working modes, this 3RPU mechanism is underactuated for four or five degrees of freedom motion, and the error is easily coupled and amplified, resulting in low end-positioning accuracy and difficulty in ensuring control stability during mooring and meeting the requirements of strong disturbance application scenarios. Furthermore, if multiple mooring devices based on traditional 6-DOF parallel mechanisms (full degree of freedom) are used in mooring scenarios, there is redundancy in the degree of freedom, resulting in complex mechanism control, large degree-of-freedom coupling, and excessive power consumption. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology by providing an automatic ship mooring device based on a parallel mechanism. This device forms a fully driven parallel mechanism through the combination of two UPU branches and two SPU branches. It can actively adapt to and compensate for the complex motion of the ship, and is easier to decouple and coordinate in control, reducing control complexity. At the same time, it effectively reduces error accumulation links, improves positioning accuracy and fault tolerance, and meets the requirements of high reliability and strong disturbance application scenarios for ship mooring.

[0007] The objective of this invention can be achieved through the following technical solutions: An automatic mooring device for ships based on a parallel mechanism includes multiple sets of mooring work units arranged along the length of the ship. Each set of mooring work units includes a base fixedly installed on the dock and a suction cup connection mechanism for adsorption connection with the ship. Four parallel kinematic chains are connected between the base and the suction cup connection mechanism, so that the suction cup connection mechanism has three-dimensional movement and rotation around an axis. Mooring buffering is achieved through the coordinated extension and retraction control of the four parallel kinematic chains. The four parallel motion chains include a first UPU chain, a second UPU chain, a first SPU chain, and a second SPU chain. The first UPU chain, the second UPU chain, the first SPU chain, and the second SPU chain are all arranged asymmetrically and eccentrically, with the eccentric mounting point located on the suction cup connection mechanism. Here, U represents a universal joint, P represents a sliding joint, and S represents a ball joint.

[0008] Preferably, the first UPU branch includes a first universal joint, a first hydraulic sliding joint, and a second universal joint arranged in sequence; the second UPU branch includes a third universal joint, a second hydraulic sliding joint, and a fourth universal joint arranged in sequence; the first SPU branch includes a first ball joint, a third hydraulic sliding joint, and a fifth universal joint arranged in sequence; and the second SPU branch includes a second ball joint, a fourth hydraulic sliding joint, and a sixth universal joint arranged in sequence. The first universal joint, the third universal joint, the first ball joint, and the second ball joint are respectively connected to corresponding positions on the base; and the second universal joint, the fourth universal joint, the fifth universal joint, and the sixth universal joint are respectively connected to corresponding positions on the suction cup connecting mechanism.

[0009] Preferably, the line connecting the first universal joint and the third universal joint is perpendicular to the line connecting the first ball joint and the second ball joint, and the rotation axis of the first universal joint and the third universal joint is perpendicular to the straight line connecting the center of the hinge point of the first universal joint and the third universal joint. The line connecting the second and fourth universal joints is perpendicular to the line connecting the fifth and sixth universal joints, and the rotation axis of the fifth and sixth universal joints is perpendicular to the straight line connecting the center of the hinge point of the fifth and sixth universal joints.

[0010] Preferably, each hydraulic moving pair in the UPU branch chain includes two hydraulic cylinders arranged in parallel.

[0011] Preferably, a hydraulic protection unit is provided inside the cylinder of the hydraulic moving pair.

[0012] Preferably, the first hydraulic sliding pair, the second hydraulic sliding pair, the third hydraulic sliding pair, and the fourth hydraulic sliding pair are replaced with an electric push rod or a ball screw mechanism driven by a servo motor.

[0013] Preferably, the ball joint in the SPU branch is a spherical bearing, the inner ring of which is fixed to the base, and the outer ring of which is connected to the interface of the sliding pair.

[0014] Preferably, the number of mooring work units is two sets, which are arranged at the bow and stern of the ship.

[0015] Preferably, the two UPU branches and the two UPU branches are V-shaped in space.

[0016] Preferably, the base is fixedly installed on the dock by anchor bolts, and the reference plane remains vertical to the ground during operation. The base is provided with one or more calibration reference surfaces or reference holes for calibrating the vertical reference and horizontal position of the base during installation.

[0017] Compared with the prior art, the present invention has the following advantages: (1) The present invention uses a hybrid parallel mechanism consisting of two UPU branches and two SPU branches for ship mooring. Only four sets of moving part drive control are needed to actively adapt to and compensate for the complex motion of the ship. It is easier to decouple and coordinate in control, reducing control complexity. At the same time, it effectively reduces error accumulation links, improves positioning accuracy and fault tolerance, and meets the requirements of high reliability and strong disturbance application scenarios for ship mooring.

[0018] (2) The present invention has two UPU branches and two SPU branches connected in parallel, realizing the coordinated bearing of mooring load among the four branches: the two UPU branches, with their clear axial constraint characteristics of universal joints, form a high-rigidity skeleton that resists lateral squeezing force and rolling moment, which can effectively suppress the lateral displacement and swaying of the ship in wind and waves, and provide crucial static stability and dynamic anti-rolling capability for mooring connection; the two SPU branches take advantage of the rotational freedom of ball joints, and exhibit good adaptive compliance when subjected to normal squeezing force, longitudinal tension and pitch / yaw moment, that is, they can flexibly buffer impact and absorb energy through extension and rotation, avoiding damage to the hull or mechanism itself caused by rigid impact.

[0019] (3) The moving pairs in the UPU and SPU branches of this invention adopt hydraulic moving pairs, which combine the high thrust, high stiffness, strong impact resistance and buffering characteristics and load sharing characteristics of the hydraulic system with the multi-degree-of-freedom and high flexibility configuration of the UPU and SPU branches to form an intelligent execution that can provide stable support during static mooring and achieve active buffering and attitude adjustment under dynamic disturbances, meeting the high safety, reliability and force control accuracy requirements of ship berthing scenarios; the parallel setting of hydraulic cylinders can provide greater output force and effectively cope with the huge impact load generated during ship mooring.

[0020] (4) In view of the sudden change of pressure / tension state during the operation of the hydraulic moving pair, the present invention has designed a targeted mechanical hydraulic protection unit in the oil cylinder to prevent hydraulic failure accidents.

[0021] (5) In this invention, the ball joint in the SPU branch chain is set as a spherical bearing, which has high radial and axial load capacity and can effectively withstand the huge impact load generated during the mooring of the ship, thus achieving a balance between rotational flexibility and heavy load stability.

[0022] (6) The two UPU branches and two SPU branches of the present invention are arranged in a V-shape in space. This specific hybrid branch configuration and spatial layout enable the suction cup connection mechanism to obtain three degrees of freedom of movement and one degree of freedom of rotation around the horizontal axis relative to the base, thereby realizing ship mooring control.

[0023] (7) The entire mooring unit in this invention has the advantages of high rigidity and large load capacity while reducing the number of drives. The base, as the static platform of the parallel mechanism, is directly fixed to the dock. The moving platform where the mooring suction cup is located remains vertical in the initial state and is directly parallel to the ship's deck panels by adjustment. All branch loads are directly transmitted to the ground or through the triangular truss. The entire mooring structure has clear force transmission, compact structure, light weight, and is easy to install. In actual engineering installation, it can be reliably installed as a component through anchor bolts, which facilitates maintenance and replacement. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of an embodiment.

[0025] Figure 2 This is a detailed structural diagram of an embodiment.

[0026] Figure 3 This is a schematic diagram of the overall structure from the rear side view of an embodiment.

[0027] Figure 4 This is a schematic diagram of the ball joint assembly in the embodiment.

[0028] Figure 5This is a schematic diagram of the overall structure of the suction cup connection mechanism in the embodiment, which is a cross-shaped structure.

[0029] Figure 6 This is a schematic diagram of the overall structure of the suction cup connection mechanism, which is a rectangular structure, in the embodiment.

[0030] Figure 7 This is a schematic diagram of the overall structure of the suction cup connection mechanism in the embodiment, which is a circular structure.

[0031] Figure 8 This is a schematic diagram of the structure of the ball joint using a universal joint-rotary joint assembly in the embodiment.

[0032] Figure 9 This is a schematic diagram of the degrees of freedom corresponding to the two sets of mooring working units in the embodiment.

[0033] Figure 10 This is a schematic diagram of the deflection displacement corresponding to the two sets of mooring working units in the embodiment.

[0034] Figure label: 1-Base, 2-Suction cup connecting mechanism, 3-First UPU branch, 31-First universal joint, 32-First hydraulic sliding pair, 33-Second universal joint, 4-Second UPU branch, 41-Third universal joint, 42-Second hydraulic sliding pair, 43-Fourth universal joint, 5-First SPU branch, 51-Fifth universal joint, 52-Third hydraulic sliding pair, 55-First spherical bearing, 6-Second SPU branch, 61-Sixth universal joint, 62-Fourth hydraulic sliding pair, 65-Second spherical bearing, 7-Flexible vacuum suction cup, 8-Electric push rod, 9-Universal joint-slewing hinge assembly, 91-Universal joint, 92-Slewing hinge; 321-First hydraulic cylinder, 322-Second hydraulic cylinder, 323-Connecting seat, 324-Connecting seat. Detailed Implementation

[0035] The technical solutions of 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, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] Example 1 like Figures 1 to 3 As shown, this embodiment provides an automatic mooring device for ships based on a parallel mechanism, including multiple mooring work units arranged along the length of the ship. Each mooring work unit includes a base 1, a suction cup connecting mechanism 2, and four parallel motion chains connected between the two, namely a first UPU chain 3, a second UPU chain 4, a first SPU chain 5, and a second SPU chain 6.

[0037] Next, we will provide a detailed explanation of each part and the work process.

[0038] (1) Base In this embodiment, the base 1 is a rectangular frame structure with two rows of mounting through holes at the bottom for use with anchor bolts to securely install it on the dock. The reference plane is kept vertical to the ground during operation. The base 1 is provided with one or more calibration reference surfaces or reference holes for calibrating the vertical reference and horizontal position of the base during installation.

[0039] (2) Suction cup connection mechanism In this embodiment, the suction cup connection mechanism 2 serves as the output end. It has a standardized flange interface at its center for installing the flexible vacuum suction cup 7, and its four ends are provided with hinge points for connecting each motion chain. The position of the hinge points can be adjusted according to the dock conditions.

[0040] In this embodiment, the first UPU branch includes a first universal joint, a first hydraulic sliding joint, and a second universal joint arranged in sequence; the second UPU branch includes a third universal joint, a second hydraulic sliding joint, and a fourth universal joint arranged in sequence; the first SPU branch includes a first ball joint, a third hydraulic sliding joint, and a fifth universal joint arranged in sequence; and the second SPU branch includes a second ball joint, a fourth hydraulic sliding joint, and a sixth universal joint arranged in sequence. The first universal joint, the third universal joint, the first ball joint, and the second ball joint are respectively connected to corresponding positions on the base; and the second universal joint, the fourth universal joint, the fifth universal joint, and the sixth universal joint are respectively connected to corresponding positions on the suction cup connecting mechanism.

[0041] As another preferred embodiment, each movable hydraulic pair includes two hydraulic cylinders arranged in parallel, and a hydraulic protection unit is provided in the hydraulic cylinder of the hydraulic movable pair, which can effectively cope with the sudden change of the pressure / tension state during the operation of the hydraulic movable pair and avoid hydraulic failure accidents.

[0042] Figure 2 A schematic diagram of the parallel arrangement of two hydraulic cylinders in the first hydraulic sliding pair 32 is given. The first hydraulic sliding pair 32 includes a first hydraulic cylinder 321 and a second hydraulic cylinder 322. The cylinder barrels of the two hydraulic cylinders are connected to the first universal joint 31 through a common rigid connecting seat 323, and their piston rods are connected to the second universal joint 33 through another common rigid connecting seat 324.

[0043] The second universal joint 33 is connected to the first hinge point of the suction cup connection mechanism 2. The second UPU branch 4 has the same structure as the first UPU branch 3. It is composed of the third universal joint 41, the second hydraulic sliding joint 42 and the fourth universal joint 43 connected in series, and is connected to the second hinge point of the base 1 and the suction cup connection mechanism 2 respectively.

[0044] The first SPU branch 5 is composed of a fifth universal joint 51, a third hydraulic sliding joint 52, and a first spherical bearing 55 connected in series. The fifth universal joint 51 is fixed to the suction cup connecting mechanism 2. The specifications of the third hydraulic sliding joint 52 are the same as those of the aforementioned hydraulic cylinder. The end of its piston rod is fixed to the inner ring of the first spherical bearing 55, and the outer ring of the first spherical bearing 55 forms a spherical fit with the third hinge point of the base 1. The second SPU branch 6 has the same structure as the first SPU branch 5, and it is composed of a sixth universal joint 61, a fourth hydraulic sliding joint 62, and a second spherical bearing 65 connected in series, and is respectively connected to the fourth hinge point of the suction cup connecting mechanism 2 and the base 1.

[0045] In this embodiment, the first UPU branch 3 and the second UPU branch 4 are arranged in a V-shape in space, as are the first SPU branch 5 and the second SPU branch 6. This specific hybrid branch configuration and spatial layout allows the suction cup connection mechanism 2 to obtain three degrees of freedom of movement and one degree of freedom of rotation about the horizontal axis relative to the base 1.

[0046] In this embodiment, the suction cup connecting mechanism 2 can adopt different shapes such as rectangular, circular, or cross-shaped structures. Figures 5-7 As shown, adapting to different spatial constraints and force distribution requirements provides more design freedom, while still achieving effective connection with the four motion chains and ensuring the 3T1R degrees of freedom of the mechanism. Specifically, the suction cup connection mechanism 2 is designed to adapt to different ship shapes and hull sizes. When the hull size is large and the ship's side is relatively flat, a rectangle is used to achieve a larger area of ​​contact; when the hull size is small and the ship's side shape is complex, a circle is used to achieve a compact arrangement.

[0047] (3) Work process During mooring operations, the base 1 is fixed to the dock, and the suction cup connection mechanism 2 is attached to the ship's side via a flexible vacuum suction cup 7. When the ship moves, the controller drives four hydraulic sliding pairs to extend and retract in coordination based on sensor signals, thereby driving the suction cup connection mechanism 2 to actively move, in order to counteract the fluctuations in mooring force and achieve intelligent and efficient mooring buffering.

[0048] In practical ship mooring applications, multiple sets of mooring work units are used to work together in order to effectively compensate for the large-scale six-degree-of-freedom motion of the hull.

[0049] Next, combined Figure 9 and Figure 10 The following is a detailed explanation using two sets of mooring work units as examples.

[0050] Two sets of mooring work units are arranged parallel to each other along the wharf at the bow and stern of the ship, with their bases fixed to the same shore base, forming a cooperative mooring assembly.

[0051] In this combination, since the distance between the two mooring work units is much larger than the size of their suction cup connection devices, the flexible vacuum suction cups connecting the hull can effectively compensate for the small rotations (usually less than ±1°) between the hull and each automatic platform around the Y and Z axes; while the larger hull yaw and pitch movements are achieved by coordinating the translational movements of the two individual work units themselves.

[0052] In this way, the hull, the two mooring work units, and the shore base together form a stable system that can actively suppress multi-degree-of-freedom motion.

[0053] Furthermore, by increasing the number of individual working units along the length of the hull, it can be expanded into an intelligent mooring system controlled collaboratively by multiple hulls, to adapt to larger ships or more complex sea conditions.

[0054] (4) Control process Input parameters: Three-degree-of-freedom angular velocity and three-degree-of-freedom acceleration measured by the IMU unit on board the ship; Feedback parameters: the stroke of each hydraulic cylinder in each mooring work unit; Control logic: A set of input parameters is first converted into the ship's six-degree-of-freedom generalized velocity and generalized displacement, and the motion (wave-following) period is calculated. This is further decomposed into motion control targets for the suction cup connection device 2 of each mooring work unit. Then, through hydraulic servo control and feedback parameters, the output parameter is the required flow rate of the corresponding cylinder, driving four motion chains to achieve the control targets, thus achieving a closed-loop motion control. The specific control algorithm can be implemented based on existing motion control algorithms; this is not the core of this invention.

[0055] This invention addresses the requirement of "6 degrees of freedom full compensation" in mooring scenarios. It abandons the traditional approach of directly implementing all degrees of freedom within a single mechanism, reducing the dimensionality to 4 degrees of freedom in a single mooring work unit. Through a special eccentric arrangement of UPU+SPU, it achieves the effect of controlling 4 degrees of freedom (full drive) with 4 drives. By combining multiple single mooring work units, the necessary 6 degrees of freedom for a ship are achieved with fewer drives (4) in the mechanism, reducing the cost of each work unit and avoiding the complexity of the (maintenance / control system).

[0056] Example 2 like Figure 5 As shown, a top plan view of an alternative embodiment of a parallel ship mooring system is illustrated. Figure 5 In the alternative implementation scheme using electric drive shown, compared with embodiment 1, the overall configuration, base 1, suction cup connection mechanism 2 and branch layout remain unchanged. The core difference lies in the replacement of the drive element.

[0057] Specifically, in this embodiment, the first hydraulic sliding joint 32, the second hydraulic sliding joint 42, the third hydraulic sliding joint 52, and the fourth hydraulic sliding joint 62 in the first UPU branch 3, the second UPU branch 4, the first SPU branch 5, and the second SPU branch 6 are all replaced with electric push rods 8 driven by servo motors. Compared with hydraulic servo, servo control has simpler logic and faster response speed, making it suitable for mooring small and light vessels.

[0058] Specifically, the cylinder end and push rod end of the electric push rod 8 are connected to the base 1 and the suction cup connection mechanism 2 via universal joints or spherical bearings of the same specifications as in the original scheme. Each electric push rod 8 integrates a servo motor with a brake to ensure that the position can be locked when power is off. The control system of this scheme consists of a programmable logic controller (PLC) and a servo driver. By receiving force and displacement sensor signals, it drives the four electric push rods 8 to extend and retract in coordination, thereby realizing the 3T1R motion and active mooring function that is completely equivalent to that of Embodiment 1.

[0059] Example 3 The difference between this embodiment and embodiment 1 is that the first joint bearing 55 and the second joint bearing 65 at the ends of the first SPU branch 5 and the second SPU branch 6 are replaced with a universal joint-swivel assembly 9.

[0060] Specifically, such as Figure 8 As shown, the universal joint-slewing hinge assembly 9 consists of a standard cross-shaft universal joint 91 connected in series with a slewing bearing 92 mounted on its output shaft. One end of the universal joint 91 is connected to the piston rod end of the third hydraulic sliding joint 52, and the other end of the slewing bearing 92 is connected to the corresponding hinge point on the chassis 1. This universal joint-slewing hinge assembly 9 provides three rotational degrees of freedom equivalent to the original ball joint (S-joint).

[0061] In this embodiment, the ball joint is set as a combination of a universal joint and a slewing hinge. The universal joint bears rotation in two directions, while the slewing hinge provides rotational freedom around the axis. The combination of the two realizes the decoupling of three degrees of freedom of rotation, and distributes the loads in different directions to the corresponding hinge units. The universal joint mainly bears radial and lateral forces, while the slewing hinge bears axial forces and torque. Under the same size, it achieves higher load-bearing capacity and overall stiffness, and is more suitable for impact and alternating loads in ship mooring.

[0062] The other settings in this embodiment are the same as in the previous embodiment.

[0063] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A marine automatic mooring device based on a parallel mechanism, characterized in that, The mooring working unit comprises a plurality of groups of mooring working units arranged along the length direction of the ship body, each group of mooring working units comprising a base fixedly installed on the wharf and a suction disc connecting mechanism for being connected with the ship by suction, four parallel motion branches being connected between the base and the suction disc connecting mechanism, so that the suction disc connecting mechanism has the freedom of three-dimensional movement and rotation around an axis, and the four parallel motion branches are cooperatively controlled by the controller to realize mooring buffering. The four parallel motion branches comprise a first UPU branch, a second UPU branch, a first SPU branch and a second SPU branch, the first UPU branch and the second UPU branch and the first SPU branch and the second SPU branch are asymmetrically arranged with eccentric mounting points on the suction disc connecting mechanism.

2. A ship automatic mooring device based on parallel mechanism according to claim 1, characterized in that, The first UPU branch comprises a first universal joint, a first hydraulic moving pair and a second universal joint arranged in sequence, the second UPU branch comprises a third universal joint, a second hydraulic moving pair and a fourth universal joint arranged in sequence, the first SPU branch comprises a first spherical hinge, a third hydraulic moving pair and a fifth universal joint arranged in sequence, and the second SPU branch comprises a second spherical hinge, a fourth hydraulic moving pair and a sixth universal joint arranged in sequence, the first universal joint, the third universal joint, the first spherical hinge and the second spherical hinge are connected to corresponding positions on the base, and the second universal joint, the fourth universal joint, the fifth universal joint and the sixth universal joint are connected to corresponding positions on the suction disc connecting mechanism.

3. A ship automatic mooring device based on parallel mechanism according to claim 2, characterized in that, The connecting line of the first universal joint and the third universal joint is perpendicular to the connecting line of the first spherical hinge and the second spherical hinge, and the rotation axis of the first universal joint and the third universal joint is perpendicular to the straight line connecting the centers of the hinge points of the first universal joint and the third universal joint. The connecting line of the second universal joint and the fourth universal joint is perpendicular to the connecting line of the fifth universal joint and the sixth universal joint, and the rotation axis of the fifth universal joint and the sixth universal joint is perpendicular to the straight line connecting the centers of the hinge points of the fifth universal joint and the sixth universal joint.

4. A ship automatic mooring device based on parallel mechanism according to claim 2, characterized in that, Each hydraulic moving pair in the UPU branch comprises two parallel hydraulic cylinders.

5. A ship automatic mooring device based on parallel mechanism according to claim 2, characterized in that, A hydraulic protection unit is arranged in the oil cylinder of the hydraulic moving pair.

6. A ship automatic mooring device based on parallel mechanism according to claim 2, characterized in that, The first hydraulic moving pair, the second hydraulic moving pair, the third hydraulic moving pair and the fourth hydraulic moving pair are replaced by electric push rods or ball screw mechanisms driven by servo motors.

7. A vessel automatic mooring system based on parallel mechanism according to claim 2 or 6, characterized in that, The spherical hinge in the SPU branch is a joint bearing, the inner ring of the joint bearing is fixed to the base, and the outer ring of the joint bearing is connected to the interface of the moving pair.

8. A ship automatic mooring device based on parallel mechanism according to claim 1, characterized in that, The number of the mooring working units is two groups, which are arranged at the bow and the stern of the ship.

9. A ship automatic mooring device based on parallel mechanism according to claim 1, characterized in that, The two UPU branches and the two SPU branches are respectively V-shaped in space.

10. A ship automatic mooring device based on parallel mechanism according to claim 1, characterized in that, The base is a static platform of the parallel mechanism, is directly fixedly installed on the wharf through foundation bolts, and the reference plane where the mooring suction disc is located is kept vertical to the ground during operation, one or more calibration reference planes or reference holes are arranged on the base, and are used for calibrating the vertical reference and the horizontal position of the base during installation.

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