Wave compensation system and control method for two-ship transfer

Abstract

The present invention provides a wave compensation system and control method for two-ship transfers, comprising a transfer ship subsystem, a receiving ship subsystem, and a composite control system. The composite control system provides signal communication between the transfer ship subsystem and the receiving ship subsystem. The transfer ship subsystem is equipped with a first wave compensation platform and a first multifunctional load platform, while the receiving ship subsystem includes a second wave compensation platform and a second multifunctional load platform. The present invention provides an active wave compensation device for two-ship transfers, capable of simultaneously isolating the wave motion of both transfer vessels to ensure stable transfer operations. Stability is maintained in both transfer modes, including personnel transfer and cargo lifting.

Description

Technical Field

[0001] The present invention relates to the field of wave compensation systems, and in particular to a wave compensation system for two-ship transfer and a control method. Background Art

[0002] The existing wave compensation systems are mainly divided into personnel transfer wave compensation systems and cargo wave compensation systems. The personnel wave compensation system is equipped with a personnel transfer gallery at the end of the multi-degree-of-freedom wave compensation platform, and the cargo wave compensation system is equipped with a lifting steel rope at the end of the multi-degree-of-freedom wave compensation platform. There is no multifunctional version of the existing wave compensation system, that is, a specific wave compensation system can only be used for personnel transfer but not for lifting. Therefore, a wave compensation system that can realize both personnel transfer and lifting is needed. Summary of the Invention

[0003] In view of the defects in the prior art, the purpose of the present invention is to provide a wave compensation system and control method for two-ship transfer.

[0004] According to the present invention, a wave compensation system for two-ship transfer is provided, comprising: a transfer ship subsystem, a receiving ship subsystem and a composite control system;

[0005] The composite control system signals connect the transfer ship subsystem and the receiving ship subsystem;

[0006] The transfer ship subsystem is provided with a first wave compensation platform and a first multifunctional load platform, and the receiving ship subsystem includes a second wave compensation platform and a second multifunctional load platform.

[0007] Preferably, the first wave compensation platform and the second wave compensation platform each include: an upper platform, a drive branch chain and a lower platform;

[0008] The upper platform is connected to the lower platform through the driving branch chain.

[0009] Preferably, the drive branch chain comprises: a servo hydraulic cylinder, a Hooke's joint and a ball joint;

[0010] The servo hydraulic cylinder is connected to the Hooke's joint and the ball joint respectively. The servo hydraulic cylinder is hingedly connected to the lower platform via the Hooke's joint, and the servo hydraulic cylinder is hingedly connected to the upper platform via the ball joint.

[0011] Preferably, the first multifunctional load platform and the second multifunctional load platform both include: a movable gallery bridge, a fixed gallery bridge, a turntable and a hook;

[0012] The fixed gallery is hinged to the turntable, the movable gallery is slidably connected to the fixed gallery via an electric slide rail, and the hook is installed at one end of the movable gallery away from the turntable.

[0013] Preferably, the turntable is fixedly connected to the upper platform.

[0014] Preferably, the composite control system is provided with a variable structure control module, an adaptive control module and a feedforward control module.

[0015] Preferably, a control method of the wave compensation system for two-ship transfer comprises the following steps:

[0016] Step S1, establishing kinematic mathematical models of the transfer ship subsystem and the receiving ship subsystem;

[0017] Inverse kinematics solution:

[0018]

[0019] in, is the single-branch vector in the lower platform coordinate system, is the position vector of the center of the upper platform relative to the center of the lower platform, is the position vector of the spherical joint in the upper platform coordinate system, is the position vector of the Hooke's hinge in the lower platform coordinate system;

[0020] Establishment of Jacobian matrix J:

[0021]

[0022]

[0023]

[0024] in, is the unit direction vector of the ith single branch, is the position vector pointing from the center of the spherical joint to the center of the upper platform;

[0025] Step S2: establishing a dynamic mathematical model of the transfer ship subsystem and the receiving ship subsystem;

[0026] Step S3: Establish the transfer function of the servo hydraulic cylinder:

[0027] Step S4: The inertial measurement unit measures the six-dimensional motion information of the lower platform;

[0028] Step S5: The controller calculates the equivalent load mass m of the servo hydraulic cylinders of the transfer ship subsystem and the receiving ship subsystem based on the six-dimensional motion information and the dynamic equation of the joint space. ti ;

[0029] The calculation formula for equivalent load mass is as follows:

[0030] M act =J -T M c J -1

[0031] Among them, M c is the mass matrix of the platform on the six-degree-of-freedom motion platform, which is a constant parameter related to the structure and mass of the upper platform;

[0032] J satisfies:

[0033] Among them: e n are six stretching velocity unit vector matrices, and

[0034]

[0035] The Jacobian matrix between the generalized velocity of the upper platform and the velocity of the upper hinge is:

[0036] Where: is the conversion matrix between the generalized velocity of the upper platform and the velocity of the joint between the upper platform and the driving branch, and:

[0037]

[0038]

[0039] Among them: α, β, γ are the rotation angles of the moving coordinate system converted from the inertial coordinate system to the Euler angle;

[0040] Among them, the antisymmetric spiral matrix of the hinge point between the upper platform and the driving branch is:

[0041]

[0042] Bi is the coordinate of the hinge point between the upper platform and the driving branch in the moving coordinate system;

[0043] Decompose the equivalent load mass matrix according to the inertia force matrix:

[0044]

[0045] in, is the residual motion acceleration matrix after load and platform compensation, is the acceleration matrix of the servo hydraulic cylinder motion.

[0046] The equivalent mass m of the i-th servo hydraulic cylinder ti M F and M G The sum of the i-th diagonal elements of .

[0047] Step S6: The adaptive control module is configured to control the load mass m ti Calculating the current transfer function and adjusting the velocity and acceleration feedback coefficients, the variable structure control module further adjusts the velocity and acceleration feedback coefficients according to the current transfer function and the position error, and the feedforward control module adjusts the feedforward compensation control amount according to gravity;

[0048] Speed ​​feedback coefficient:

[0049] Acceleration feedback coefficient:

[0050]

[0051] in:

[0052] Ap is the effective area of ​​the hydraulic servo cylinder piston;

[0053] Bp is the viscous damping coefficient of the piston and equivalent load;

[0054] Kq is the flow gain coefficient of the hydraulic servo cylinder slide valve

[0055] Kc is the pressure gain coefficient of the hydraulic servo cylinder slide valve

[0056] C1: It is expected that the natural frequency remains unchanged when the element parameters change:

[0057]

[0058] C2: It is expected that the damping ratio remains unchanged when the element parameters change:

[0059]

[0060] m L is the equivalent mass, B p is the damping coefficient, x p is the cylinder position;

[0061] ω n Natural frequency:

[0062] β e is the effective bulk elastic modulus (including the mechanical flexibility of the oil, connecting pipes, and cylinder body)

[0063] set up

[0064] A p A is the working area of ​​the cylinder piston chamber, g is the working area of ​​the oil cylinder piston chamber;

[0065] V1=V 01 +A px p , V2=V 02 -A p x p

[0066] V 01 is the initial volume of the oil inlet chamber of the cylinder, V 02 is the initial volume of the oil return chamber of the cylinder;

[0067] Step S7: the composite control system sends the calculated control signal to the servo valve, which drives the servo hydraulic cylinder to adjust the length of the drive branch chain so that the upper platform remains stationary relative to the absolute reference system.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] 1. The present invention provides an active wave compensation device that can be used for two-ship transfer. It can simultaneously isolate the wave motion of the two transfer vessels to ensure the stability of the transfer operation. The transfer mode includes two working conditions, including personnel transfer and cargo lifting, and the stability can be guaranteed in both conditions.

[0070] 2. The present invention adopts a composite control system, including a variable structure control module, an adaptive control module and a feedforward control module. The variable structure control module can adjust its own parameters according to the position and speed errors of the electro-hydraulic servo system relative to the control target to ensure rapid responsiveness and avoid excessive overshoot and settling time.

[0071] The adaptive control module adjusts its own parameters based on the equivalent load mass of the current electro-hydraulic servo system calculated by dynamics to adapt to changes in load mass, making the transfer function more accurate;

[0072] The feedforward control module predicts in advance the influence of other branches on the single-branch electro-hydraulic servo system based on the equivalent coupled inertial force calculated by the dynamic solution, thereby compensating for the disturbing inertial force.

[0073] 3. The present invention is applicable to various application scenarios such as ship-to-ship transfer, wind turbine operation and maintenance, and recovery of unmanned aerial vehicles by surface ships. It can be installed in multiple locations or equipment and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0075] Figure 1 This is a schematic diagram of the wave compensation system when two ships are transferring;

[0076] Figure 2 This is a structural diagram of the heave compensation system;

[0077] Figure 3Schematic diagram of the transfer ship subsystem or receiving ship subsystem structure;

[0078] Figure 4 Schematic diagram of the drive branch chain structure;

[0079] Figure 5 This is a structural diagram of the wave compensation platform;

[0080] Figure 6 This is the schematic diagram of the composite control system;

[0081] As shown in the figure:

[0082]

[0083] DETAILED DESCRIPTION

[0084] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0085] Example 1

[0086] like Figure 1 As shown, this embodiment includes a transfer vessel subsystem, a receiving vessel subsystem, and a composite control system. The composite control system provides signal connections between the transfer vessel subsystem and the receiving vessel subsystem. The transfer vessel subsystem is equipped with a first wave compensation platform and a first multi-functional load platform, while the receiving vessel subsystem includes a second wave compensation platform and a second multi-functional load platform. The composite control system includes a variable structure control module, an adaptive control module, and a feedforward control module.

[0087] like Figure 2 and Figure 3 As shown, both the first and second heave compensation platforms include an upper platform 4, a drive chain 5, and a lower platform 6. The upper platform 4 is connected to the lower platform 6 via the drive chain 5. The first and second multifunctional load platforms also include a movable bridge 1, a fixed bridge 2, a turntable 3, and a hook 7. The fixed bridge 2 is hinged to the turntable 3, and the movable bridge 1 is slidably connected to the fixed bridge 2 via an electric slide rail. The hook 7 is mounted on the end of the movable bridge 1 away from the turntable 3. The turntable 3 is fixedly connected to the upper platform 4.

[0088] like Figure 4As shown, the drive branch chain 5 includes: a servo hydraulic cylinder 8, a Hooke's joint 9 and a ball joint 10; the servo hydraulic cylinder 8 is connected to the Hooke's joint 9 and the ball joint 10 respectively, the servo hydraulic cylinder 8 is hingedly connected to the lower platform 6 through the Hooke's joint 9, and the servo hydraulic cylinder 8 is hingedly connected to the upper platform 4 through the ball joint 10.

[0089] like Figure 5 As shown, coordinate systems are established at the centers of the upper platform 4 and the lower platform 6, respectively. The control method of the wave compensation system for the transfer of two ships includes the following steps:

[0090] Step S1, establishing kinematic mathematical models of the transfer ship subsystem and the receiving ship subsystem;

[0091] Inverse kinematics solution:

[0092]

[0093] in, is the single-branch vector in the lower platform 6 coordinate system, is the position vector of the center of the upper platform 4 relative to the center of the lower platform 6, is the position vector of the spherical joint 10 in the coordinate system of the upper platform 4, is the position vector of Hooke's hinge 9 in the coordinate system of the lower platform 6;

[0094] Establishment of Jacobian matrix J:

[0095]

[0096]

[0097]

[0098] in, is the unit direction vector of the ith single branch, is the position vector pointing from the center of the spherical joint 10 to the center of the upper platform 4;

[0099] Step S2: establishing dynamic mathematical models of the transfer ship subsystem and the receiving ship subsystem;

[0100] Step S3: Establish the transfer function of the servo hydraulic cylinder 8:

[0101] Step S4: The inertial measurement unit measures the six-dimensional motion information of the lower platform 6;

[0102] Step S5: The controller calculates the equivalent load mass m of the servo hydraulic cylinder 8 of the transfer ship subsystem and the receiving ship subsystem based on the six-dimensional motion information and the dynamic equation of the joint space. ti ;

[0103] Step S6: The adaptive control module is based on the equivalent load mass m ti The current transfer function is calculated and the velocity and acceleration feedback coefficients are adjusted. The variable structure control module adjusts the velocity and acceleration feedback coefficients again based on the current transfer function and position error. The feedforward control module adjusts the feedforward compensation control amount based on gravity. Feedforward control refers to adding a certain value to the controller parameters to compensate for the influence of gravity.

[0104] Step S7: The composite control system sends the calculated control signal to the servo valve, which drives the servo hydraulic cylinder 8 to adjust the length of the drive branch chain 5 so that the upper platform 4 remains stationary relative to the absolute reference system.

[0105] Example 2

[0106] Example 2 is a preferred example of Example 1.

[0107] like Figures 1 to 4 As shown, this embodiment includes: a transfer ship subsystem, a receiving ship subsystem and a composite control system.

[0108] The transfer ship subsystem and the receiving ship subsystem include a wave compensation platform and a multifunctional load platform respectively. The composite control system includes a variable structure control module, an adaptive control module and a feedforward control module.

[0109] The wave compensation platform comprises a lower platform 6, an upper platform 4 and six drive branches 5; the lower platform 6 is fixedly connected to the deck through anchor bolts.

[0110] The multifunctional load platform consists of a turntable 3, a fixed gallery 2, a movable gallery 1, and a hook 7. The turntable 3 is securely connected to the upper platform 4 of the heave compensation platform via anchor bolts. The gallery consists of two parts: the fixed gallery 2 and the movable gallery 1. The movable gallery 1 uses electric slides to achieve telescopic movement relative to the fixed gallery 2. The fixed gallery 2 is hinged to the turntable 3 and driven by a motor to achieve pitch and roll relative to the turntable 3. The turntable 3 is used to rotate the multifunctional load platform relative to the upper platform 4 of the heave compensation platform. The hook 7 is mounted at the end of the movable gallery for loading cargo.

[0111] When the wave compensation system for transferring two ships operates in personnel transfer mode, the movable corridor 1 of the transfer ship subsystem and the receiving ship subsystem are connected. The composite control system uses the wave motion of the two ships as information input to control the connected movable corridor 1 to remain stable relative to the ground, allowing personnel to be transferred between the two ships comfortably and safely.

[0112] When the heave compensation system for ship-to-ship transfers operates in cargo transfer mode, cargo is suspended from the transfer vessel subsystem's hook 7. The bridge and turntable 3 act like a crane arm, rotating and moving to transfer the cargo. The composite control system directs the heave compensation platform of the transfer vessel subsystem to offset the motion of the transfer vessel, protecting the cargo from the effects of the transfer vessel's waves. Simultaneously, the composite control system directs the heave compensation platform of the receiving vessel subsystem to offset the motion of the receiving vessel, ensuring a stable cargo placement.

[0113] The driving branch chain 5 includes: a servo hydraulic cylinder 8, a Hooke's hinge 9 and a ball joint 10. The Hooke's hinge 9 is installed at the bottom of the cylinder body of the servo hydraulic cylinder 8 and is hinged to the hinge support of the lower platform 6. The ball joint 10 is installed at the top of the push rod of the servo hydraulic cylinder 8 and is hinged to the hinge support of the upper platform 4.

[0114] Example 3

[0115] First, the sensors in the composite control system collect information about the ship's motion. Based on this information, the controller in the adaptive control module calculates the maximum length of the drive chains 5 required to maintain platform stability. This calculation is based on an inverse kinematic solution: the input is the 3D position and 3D angle information of the upper platform 4 relative to the lower platform 6, and the output is the target length of the six drive chains 5.

[0116] The target length of the six drive chains 5 is the controller's control target. The controller changes the length of the six drive chains 5 by driving the servo hydraulic cylinders 8, thereby enabling the drive chains 5 to reach the target length. However, the first difficulty lies in the sluggish response of the servo hydraulic cylinders 8. The heave compensation platform requires not only that the drive chains 5 accurately reach the target length, but also that they reach the target length within a specified time. If the drive chains 5 reach the target length too slowly, it is considered a control failure. To enable the hydraulic cylinders to quickly reach the target length, the controller increases the current, causing the servo hydraulic cylinders 8 to move rapidly. However, this introduces a second difficulty: if the servo hydraulic cylinders 8 move too quickly, due to inertia, they cannot stop in time after reaching the target length, resulting in an overshoot (the excess length is called overshoot). The ideal control characteristics of the servo hydraulic cylinders 8 can be summarized as: achieving the desired control length quickly and in a timely manner, while avoiding excessive overshoot. Overshoot can cause the upper platform of the heave compensation platform to produce a small but rapid residual motion, potentially damaging the equipment. The third difficulty is that the servo hydraulic cylinder 8 used in the heave compensation platform typically has a very long stroke. The optimal controller PID parameter range varies for different stroke lengths. Therefore, during the control process, the controller may need to continuously adjust its parameters to achieve optimal performance. Difficulties 1 and 2 can be considered local parameter adjustments, while difficulty 3 can be considered global parameter adjustments.

[0117] In one embodiment, taking the P parameter as an example, the adjustment principle of the I and D parameters is similar. The stroke range of the servo hydraulic cylinder 8 is 2m. When it is at the stroke position of 1.5m, it is hoped that it can reach the position of 1.8m within 1 second. Then, at the beginning of the movement, due to the large difference between 1.5m and 1.8m, the controller can use a large current, that is, a large P value to drive the servo hydraulic cylinder 8 to achieve rapid upward movement. When the servo hydraulic cylinder 8 approaches a position of about 1.75m, the movement speed of the servo hydraulic cylinder 8 should be slowed down, that is, the P value should be reduced so that the speed of the hydraulic cylinder is almost zero when it reaches 1.8m, which can avoid overshoot. How to achieve rapid movement to the target value within 1 second and maintain stability when reaching the target value can be achieved by adopting a variable structure control strategy.

[0118] In another embodiment, the desired target value remains at 1.8 m, but the servo hydraulic cylinder 8 is now at a stroke of 0.5 m. The optimal P parameter ranges for the servo hydraulic cylinder 8 at 1.5 m and 0.5 m differ significantly. This is due to the mechanical, oil, and equivalent load characteristics of the servo hydraulic cylinder 8. Determining the optimal P parameter range based on the current stroke and equivalent load of the servo hydraulic cylinder 8 can be achieved using an adaptive control strategy.

[0119] In summary, the controller design of the present invention primarily addresses two key issues. The adaptive control strategy focuses on determining the current position of servo hydraulic cylinder 8 and its equivalent load, and then determines the optimal initial PID parameter values. The variable structure control strategy focuses on determining how far away servo hydraulic cylinder 8 is from its target value and how quickly it is expected to reach that value. Based on the initial PID parameter values ​​determined by the adaptive method, the parameters are then adjusted. The adaptive and variable structure control strategies work together to complete the controller's workflow.

[0120] The design idea of ​​the adaptive method is: the controller calculates the velocity and acceleration feedback coefficients according to the current position of the servo hydraulic cylinder 8, the value of the equivalent load, and the expected response characteristics, thereby determining the initial values ​​of the optimal PID parameters of the servo hydraulic cylinder 8.

[0121] Design idea of ​​variable structure method: On the basis of the adaptive method, the controller further corrects the speed and acceleration feedback coefficients calculated above according to the error between the current position of the servo hydraulic cylinder 8 and the target position, and then improves the PID parameters.

[0122] In response to complex uncertainties, the design concept of the composite control strategy of the heave compensation platform includes two parts:

[0123] An adaptive control strategy is employed, primarily targeting the dynamic characteristics of a six-degree-of-freedom parallel mechanism and the hydraulic characteristics determined by cylinder position. This type of problem is characterized by deterministic, predictable, and compensable changes in parameter characteristics. First, velocity and acceleration feedback are introduced into the system. By solving the mechanism's dynamics and constructing a hydraulic transfer function for the valve-controlled cylinder, the velocity and acceleration feedback coefficients are made functions of variations in parameters such as equivalent mass, velocity coefficient, cylinder position, and motion state. This adaptive velocity and acceleration feedback coefficients stabilize the control system's characteristics.

[0124] A variable structure control strategy is employed. Given that the oscillation amplitude caused by system overshoot is relatively small and occurs when the output reaches or approaches the command signal, that is, output error Δ = YX ≈ 0, a two-stage transfer function is established for the output error Δ. For large errors, an underdamped transfer function with large overshoot is used to improve system responsiveness; for small errors, an overdamped transfer function with no overshoot is used. The system gain, velocity, and acceleration coefficients are designed as functions of the error Δ, increasing the natural frequency and the damping ratio to achieve the transfer function characteristics described above.

[0125] The wave compensation platform adapts to and offsets the impact of the hull's swaying and heaving caused by waves on the work platform by controlling the posture of the six-degree-of-freedom parallel mechanism, thereby keeping the work platform stationary. The six-degree-of-freedom parallel mechanism is driven by six servo hydraulic cylinders 8. Due to the characteristics of the mechanism, the equivalent load mass and velocity coefficient borne by the servo hydraulic cylinder 8 of each drive branch 5 when moving in different postures of the platform are variable; at the same time, the hydraulic stiffness of the servo hydraulic cylinder 8 at different stroke positions is also variable. Mass, damping, and stiffness are the three major factors that determine the response characteristics of the control system. As they change significantly, the response characteristics of the control system become unstable. The adaptive control strategy based on dynamic analysis is to achieve stable control characteristics by adjusting the speed and acceleration feedback coefficients.

[0126] The mass, damping, and stiffness factors discussed above are concentrated in the valve-controlled cylinder link. By maintaining the control characteristics of the valve-controlled cylinder system stable through adaptive control, the adaptive control objective can be achieved. The velocity feedback coefficient, Kv, can be adjusted to maintain a constant undamped oscillation frequency. By varying the acceleration feedback coefficient, the damping ratio remains constant, ensuring that the control system's response characteristics remain unchanged with changes in the equivalent load mass.

[0127] The equivalent mass and velocity coefficients of a single-branch drive control system for a six-degree-of-freedom parallel mechanism significantly impact the platform's control performance. Real-time calculation of these coefficients is a prerequisite for designing an adaptive control strategy. This strategy is based on an analysis of the platform's kinematics, dynamics, and the cross-linked load coupling between channels. First, using matrix and vector analysis methods, an inverse mathematical model for position, velocity, and acceleration is established. Secondly, the Lagrangian method is used to analyze the forces acting on the platform. The D'Alembert principle of a system of particles and the force equivalence method are employed to establish the upper platform's force (torque) balance equations. The Kane method is then used to establish the standard dynamic equations for the six-degree-of-freedom platform's task workspace and the dynamic equations for the platform's joint workspace. The equivalent mass and velocity coefficients of each branch control system are then calculated in real time.

[0128] Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, and units provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same functions of the system and its various devices, modules, and units provided by the present invention in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; the devices, modules, and units for implementing various functions can also be considered as both software modules implementing the method and structures within the hardware component.

[0129] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0130] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A control method for a wave compensation system for two-ship transfer, characterized in that: A wave compensation system for two-ship transfer, including a transfer ship subsystem, a receiving ship subsystem, and a composite control system; The composite control system signals connect the transfer ship subsystem and the receiving ship subsystem; The transfer ship subsystem is provided with a first wave compensation platform and a first multifunctional load platform, and the receiving ship subsystem includes a second wave compensation platform and a second multifunctional load platform; The first wave compensation platform and the second wave compensation platform both comprise: an upper platform (4), a drive branch chain (5) and a lower platform (6); The upper platform (4) is connected to the lower platform (6) via the drive branch chain (5); The drive branch chain (5) includes: a servo hydraulic cylinder (8), a Hooke's joint (9) and a ball joint (10); The servo hydraulic cylinder (8) is respectively connected to the Hooke's hinge (9) and the ball hinge (10); the servo hydraulic cylinder (8) is hingedly connected to the lower platform (6) via the Hooke's hinge (9); and the servo hydraulic cylinder (8) is hingedly connected to the upper platform (4) via the ball hinge (10); The first multifunctional load platform and the second multifunctional load platform both comprise: a movable gallery (1), a fixed gallery (2), a turntable (3) and a hook (7); The fixed gallery (2) is hinged to the turntable (3), the movable gallery (1) is slidably connected to the fixed gallery (2) via an electric slide rail, and the hook (7) is installed at one end of the movable gallery (1) away from the turntable (3); The composite control system is provided with a variable structure control module, an adaptive control module and a feedforward control module; The following steps are involved: Step S1, establishing kinematic mathematical models of the transfer ship subsystem and the receiving ship subsystem; Inverse kinematics solution: in, is the single-branch vector in the coordinate system of the lower platform (6), is the position vector of the center of the upper platform (4) relative to the center of the lower platform (6), is the position vector of the spherical joint (10) in the coordinate system of the upper platform (4), is the position vector of the Hooke's joint (9) in the coordinate system of the lower platform (6); Step S2: establishing a dynamic mathematical model of the transfer ship subsystem and the receiving ship subsystem; Step S3: Establish the transfer function of the servo hydraulic cylinder (8): Step S4: measuring the six-dimensional motion information of the lower platform (6); Step S5: Calculate the equivalent load mass m of the servo hydraulic cylinder (8) of the transfer ship subsystem and the receiving ship subsystem based on the six-dimensional motion information ti ; Step S6: The adaptive control module adjusts the current length of the drive branch chain (5) and the equivalent load mass m ti Calculate the current transfer function, adjust the speed and acceleration feedback coefficients, and determine the optimal initial value of PID control. The variable structure control module adjusts the speed and acceleration feedback coefficients again based on the current transfer function and position error, and continues to adjust the parameter values ​​based on the optimal initial value of PID. The feedforward control module adjusts the feedforward compensation control amount according to gravity. Step S7: The composite control system sends the calculated control signal to the servo valve, and the servo valve drives the servo hydraulic cylinder (8) to adjust the length of the drive branch chain (5) so that the upper platform (4) remains stationary relative to the absolute reference system; Speed ​​feedback coefficient: Acceleration feedback coefficient: in: β e is the effective bulk elastic modulus; Ap is the effective area of ​​the hydraulic servo cylinder piston; Bp is the viscous damping coefficient of the piston and equivalent load; Kq is the flow gain coefficient of the hydraulic servo cylinder slide valve; Kc is the pressure gain coefficient of the hydraulic servo cylinder slide valve; C1: It is expected that the natural frequency remains unchanged when the element parameters change: C2: It is expected that the damping ratio remains unchanged when the element parameters change: m L is the equivalent mass, B p is the damping coefficient, x p is the cylinder position; ω n Natural frequency: set up A p A is the working area of ​​the cylinder piston chamber, g is the working area of ​​the cylinder piston chamber; V1=V 01 +A p x p ,V2=V 02 -A p x p V 01 is the initial volume of the oil inlet chamber of the cylinder, V 02 It is the initial volume of the oil return chamber of the cylinder.

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