A high compensation accuracy hybrid semi-active heave compensation system and method

Abstract

The application belongs to the technical field of heave compensation, and provides a high-compensation-precision hybrid semi-active heave compensation system and a control method. The high-compensation-precision hybrid semi-active heave compensation system comprises a pulley block, a cable storage winch system, an active control device, a passive control device, a control unit and a sensing assembly. The active control device and the passive control device are both vertical structures. A movable pulley is arranged at the top of the active control device and the passive control device. In the passive heave compensation mode, the movable pulley can move up and down along the vertical direction under the action of the passive control device alone. In the semi-active compensation mode, the movable pulley can move up and down along the vertical direction under the joint action of the active control device and the passive control device. The sensing assembly senses heave signals of a mother ship and displacement signals of the passive control device and transmits the signals to the control unit. The control unit controls the active control device to generate a movement opposite to the heave direction of the mother ship according to the received signals.

Description

Technical Field

[0001] This invention belongs to the field of heave compensation technology, and particularly relates to a hybrid semi-active heave compensation system and method with high compensation accuracy. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Tethered underwater robots (ROVs) and offshore wind turbines are common loads used in offshore operations. Offshore wind turbines are connected to the end of a marine crane via steel cables, while ROVs are connected to repeaters via umbilical cables. The repeaters are then connected to a surface vessel via long umbilical cables. During operations, these loads inevitably face the heave and sway caused by waves on the hull and the ROV / wind turbine. In severe cases, this can lead to collisions between the ROV / wind turbine and the repeater or the hull, causing significant damage. Similar issues exist in offshore load lifting between vessels and wind farm construction. Therefore, appropriate compensation must be provided for the heave and sway of vessels during offshore operations to ensure the smooth progress of these tasks.

[0004] While existing heave compensation technologies employ modular linear switched reluctance motors as the core component of active control devices, effectively reducing thrust fluctuations, motor vibration, and noise, and further mitigating these effects through well-designed control methods, the power density and system efficiency of linear switched reluctance motors remain lower than those of permanent magnet linear motors due to their inherent characteristics. Thrust fluctuations and vibration noise can only be suppressed as much as possible (especially during commutation), not fundamentally resolved. Therefore, their application is limited in situations requiring higher power density, greater heave compensation thrust, higher system compensation accuracy, and lower equipment noise. Summary of the Invention

[0005] To address the technical problems mentioned above, this invention provides a hybrid semi-active heave compensation system and control method with high compensation accuracy. The compensation system has the advantages of simple structure, good control effect, small weight and volume saving deck space, high stability and compensation accuracy, low energy consumption, and large thrust, making it suitable for heavy loads.

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

[0007] The first aspect of the present invention provides a hybrid semi-active heave compensation system with high compensation accuracy.

[0008] A high-precision hybrid semi-active heave compensation system includes a pulley block, a cable storage winch system, an active control device, a passive control device, a control unit, and a sensing component; the pulley block includes a movable pulley and a fixed pulley.

[0009] The cable storage winch system is connected to one end of the hoisting cable, and the other end of the hoisting cable is connected to the hoisting load via a movable pulley and a fixed pulley in sequence;

[0010] Both the active control device and the passive control device are vertical structures;

[0011] The movable pulley is installed on top of the active control device and the passive control device; in the passive heave compensation mode, the movable pulley can move up and down in the vertical direction under the action of the passive control device alone; in the semi-active compensation mode, the movable pulley can move up and down in the vertical direction under the combined action of the active control device and the passive control device.

[0012] The passive control device is used to passively generate drive signals based on the heave motion of the mother ship to control the movement of the movable pulley;

[0013] The sensing component is used to sense the heave signal of the mother ship and the displacement signal of the passive control device and transmit them to the control unit. The control unit is used to control the active control device to generate a movement opposite to the heave direction of the mother ship according to the received signals, so as to work together with the passive control device to control the movable pulley to move up and down in the vertical direction.

[0014] In one implementation, the active control device is a motor, and the passive control device is a hydraulic cylinder.

[0015] In one implementation, the active control device consists of two motors; the passive control device consists of two hydraulic cylinders; wherein, the two linear motors are located inside the two hydraulic cylinders, and the hydraulic cylinders and linear motors are symmetrically placed.

[0016] In one implementation, the motor is a permanent magnet linear motor.

[0017] In one embodiment, the permanent magnet linear motor includes a stator permanent magnet, a mover, a three-phase armature winding wound on the mover, and a stator track. The stator permanent magnet is laid at equal intervals on the stator track and arranged alternately according to different polarities. The three-phase winding is assembled inside the mover.

[0018] In one implementation, two hydraulic cylinders are symmetrically placed on both sides of the pulley with the central axis of the movable pulley as the center line. Each hydraulic cylinder is equipped with an oil-gas separator, a pressure control unit, and three gas storage cylinders.

[0019] In one embodiment, the hydraulic cylinder consists of a cylinder barrel and a piston, including a rod chamber and a rodless chamber, the rodless chamber being an oil-filled chamber, and a position sensor is arranged at the piston rod end to detect the position of the piston rod.

[0020] In one implementation, the piston end is connected to the base via a hinge to provide passively compensated thrust, the rod chamber is connected to the oil tank via an oil passage, and the oil hole at the bottom of the rodless chamber is connected to the oil-gas separator via an oil passage.

[0021] In one embodiment, the movable pulley is mounted on a movable pulley base, which is connected to the drive end of the passive control device. The movable pulley base is also connected to a transmission base, which is connected to a support plate. The support plate is connected to a guide rail, which is vertically positioned outside the active control device. The support plate can move passively along the guide rail under the action of the drive end of the passive control device or move along the guide rail under the active drive of the active control device.

[0022] A second aspect of the present invention provides a control method for a hybrid semi-active heave compensation system with high compensation accuracy.

[0023] A control method employing a hybrid semi-active heave compensation system with high compensation accuracy as described above includes: preparation work, passive heave compensation mode, and active heave compensation mode.

[0024] When the working mode is in the standby mode, only the passive control device is activated and placed in the preset initial state;

[0025] When the working mode is passive heave compensation mode, only the passive control device works;

[0026] When the working mode is switched to semi-active compensation mode, the passive control device and the active control device operate simultaneously.

[0027] As one implementation method, when the heave compensation motion of the mother ship caused by waves is less than or equal to a preset threshold range, the high-compensation-precision hybrid semi-active heave compensation system is put into passive heave compensation mode.

[0028] As one implementation method, when the heave compensation motion of the mother ship caused by waves exceeds the preset threshold range, the high-compensation-precision hybrid semi-active heave compensation system is only put into semi-active compensation mode.

[0029] The beneficial effects of this invention are:

[0030] (1) The semi-active heave compensation system of the present invention adopts a vertical structure, with the moving pulley placed at the top of the entire heave compensation device, which makes the compensation stroke less restricted and saves deck space; moreover, the active control device and the passive control device are symmetrically arranged, which is a distributed structure, with greater compensation force, faster response speed and less compensation lag.

[0031] (2) This invention is more suitable for offshore operations involving large-volume, heavy loads that are easily affected by surface and seabed waves, and for work environments with harsh conditions (large surface waves and turbulent seabed). It can be used in offshore operations such as large-scale tethered underwater robot operations, large-scale offshore wind farm construction, sea transport and hoisting of wind turbines and their components, and large-scale offshore oil field construction, providing heave compensation displacement to ensure the safety of operating equipment and personnel.

[0032] (3) A permanent magnet linear motor is used as a transmission mechanism to complete the reciprocating linear motion. The linear motor is placed symmetrically on both sides with the central axis of the movable pulley as the axis. The motor drive circuit drives the linear motor to reciprocate to provide the energy for active heave compensation. The hydraulic device and hydraulic compensation cylinder provide the energy for passive compensation. This compensation system has the advantages of simple structure, good control effect, small weight and volume to save deck space, high stability and compensation accuracy, low energy consumption and large thrust, which can be applied to heavy loads.

[0033] (4) This invention utilizes a permanent magnet linear motor, which has a smaller size and lower energy consumption at the same output power, and can be applied to offshore operation systems with higher power requirements and lower energy loss requirements; moreover, the thrust fluctuation of the permanent magnet linear motor is reduced, making the thrust output smoother, and making the lifting load more stable during the lowering or recovery process, thus improving the safety and stability of offshore lifting operations (wind turbines, oil field construction, underwater robots); the reduction of noise reduces the overall noise of the semi-active control device, and the reduction of vibration can further reduce the thrust fluctuation of the motor output, extend the device life, improve the working reliability, and improve the control accuracy, thus further improving the system compensation accuracy; it is suitable for occasions with high power and thrust requirements, low noise, and high compensation accuracy.

[0034] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1This is a schematic diagram of the structure of a hybrid semi-active heave compensation system with high compensation accuracy according to an embodiment of the present invention.

[0037] The components are: 1. Mother ship, 2. Cable storage winch system, 3. Moving pulley, 4. Fixed pulley, 5. Hydraulic cylinder, 6. Piston rod, 7. Gas accumulator, 8. Stator, 9. Mover, 10. Mover slider, 11. Long baffle, 12. Short baffle, 13. Mover support plate, 14. Mover position sensor, 15. Piston rod position sensor, 16. Motor transmission base, 17. Mother ship heave motion detection unit, 18. Lifting cable. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] Terminology Explanation:

[0042] Permanent magnet linear motor: The long stator of a permanent magnet linear motor is a permanent magnet, and the short mover contains an armature winding. Its primary rotor does not need to generate a magnetic field through primary reactive current. Therefore, it has the advantages of high efficiency, good heat dissipation, high power factor and high thrust density. Moreover, the excitation power through the secondary rotor is small. On ships, it can appropriately reduce the power capacity and weight of the ship. It plays an excellent role in heave compensation systems that require control precision and compensation stroke.

[0043] Replacing the hydraulic system with a linear motor can reduce hydraulic lines, improve system efficiency, provide fast response, short acceleration and deceleration processes, theoretically have unlimited compensation stroke, facilitate equipment maintenance, improve stability and fault tolerance, and reduce pollution caused by oil leaks to the environment.

[0044] according to Figure 1This embodiment provides a high-accuracy hybrid semi-active heave compensation system, including a pulley block and a cable storage winch system; the pulley block includes movable pulleys and fixed pulleys; the high-accuracy hybrid semi-active heave compensation system further includes: an active control device, a passive control device, a control unit, and a sensing component.

[0045] exist Figure 1 In the process, the cable storage winch system 2 is connected to one end of the hoisting cable 18, and the other end of the hoisting cable 18 is connected to the hoisting load through the movable pulley 3 and the fixed pulley 4 in sequence; the cable storage winch system 18 and the fixed pulley 4 are both fixed on the mother ship 1.

[0046] Specifically, the fixed pulley 4 can be fixed to the mother ship 1 via a support frame.

[0047] Both the active control device and the passive control device are vertical structures;

[0048] The movable pulley is installed on top of the active control device and the passive control device; in the passive heave compensation mode, the movable pulley can move up and down in the vertical direction under the action of the passive control device alone; in the semi-active compensation mode, the movable pulley can move up and down in the vertical direction under the combined action of the active control device and the passive control device.

[0049] The passive control device is used to passively generate drive signals based on the heave motion of the mother ship to control the movement of the movable pulley;

[0050] The sensing component is used to sense the heave signal of the mother ship and the displacement signal of the passive control device and transmit them to the control unit. The control unit is used to control the active control device to generate a movement opposite to the heave direction of the mother ship according to the received signals, so as to work together with the passive control device to control the movable pulley to move up and down in the vertical direction.

[0051] In some specific implementations, the active control device is a motor, and the passive control device is a hydraulic cylinder.

[0052] The movable pulley is mounted on a movable pulley base, and the movable pulley base is connected to the drive end of the passive control device (e.g., Figure 1 The piston rod 6 in the middle is connected to the end of the piston rod 6. The movable pulley base is also connected to the transmission base (e.g., the end of the piston rod 6 in the middle). Figure 1 The motor drive base 16 is connected to the motor drive base (e.g., the motor drive base 16), and the drive base is connected to the support plate (e.g., the motor drive base 16). Figure 1 The moving part support plate 13 is connected to the guide rail (e.g., made of...). Figure 1 The long baffle 11 and the short baffle 12 are connected together. The guide rail is vertically arranged on the outside of the active control device. The support plate can move passively along the guide rail under the action of the drive end of the passive control device or move along the guide rail under the active drive of the active control device.

[0053] In this embodiment, the active control device consists of two motors; the passive control device consists of two hydraulic cylinders; wherein, the two linear motors are located inside the two hydraulic cylinders, and the hydraulic cylinders and linear motors are symmetrically placed.

[0054] Figure 1 As shown, the guide rail in this embodiment is composed of a long baffle 11 and a short baffle 12. The motor in this embodiment is a permanent magnet linear motor. There are two permanent magnet linear motors, symmetrically positioned on both sides of the central axis of the movable pulley to provide sufficient thrust for heave compensation. There are two identical bases for the linear motors. There are four identical long baffles 11 and four identical short baffles 12, with their bottom ends fixed to the bases along with the motor stator. The two long baffles 11 and two short baffles 12 on each side are arranged in a rectangular configuration, with the permanent magnet linear motor positioned between the long and short baffles.

[0055] The drive mechanism of the semi-active control device is thus composed of two identical hydraulic cylinders and two identical permanent magnet linear motors, providing greater heave compensation thrust to drive the load.

[0056] Specifically, the permanent magnet linear motor includes a stator permanent magnet 8, a mover 9, a three-phase armature winding wound on the mover, and a stator track. The stator permanent magnets are laid at equal intervals on the stator track and are arranged alternately according to different polarities. The three-phase winding is assembled inside the mover.

[0057] In this embodiment, the active control device includes a drive mechanism: it is a permanent magnet linear motor composed of a stator permanent magnet 8, a mover 9, a mover slider 10, a mover position sensor 14, a long baffle 11, a short baffle 12, and a base. The transmission mechanism includes a mover support plate 13 and a motor transmission base 16. The permanent magnet 8 of the permanent magnet linear motor is fixed on the bottom base. The mover 9 contains windings and is connected to the guide rail through the mover slider 10 to reduce friction loss. The overall arrangement is rectangular. The mover 9 is cast and embedded under the mover support plate 13. The motor transmission base 16 is embedded on the mover support plate 13. The top end is connected to the bottom partition of the movable pulley through a hinge. The entire active lifting compensation transmission structure is driven by the mover of the permanent magnet linear motor, which in turn drives the movable pulley to move and provides active compensation power.

[0058] In this example, the thrust and displacement of the permanent magnet linear motor are precisely adjusted by the control component according to compensation requirements. An incremental displacement sensor 14 is installed on the baffle of the mover 9, which is externally embedded in the mover baffle. The displacement sensor 14 is used to measure the displacement of the mover and feeds the measured displacement back to the control system. It is compared with the heave displacement of the mother ship detected by the mother ship heave motion detection unit (MRU), thereby controlling the reciprocating motion of the mover according to the algorithm pre-designed by the control system.

[0059] In this embodiment, long baffles are symmetrically arranged on both sides of the slider of the permanent magnet linear motor. The long and short baffles are in the form of a cuboid structure. The motor itself is also centrally symmetrical, which ensures the relative constancy of the air gap of the motor. Theoretically, this eliminates the noise and vibration problems caused by the imbalance of the normal force perpendicular to the direction of motion. A guide rail is provided on the upper side of the long baffle to fix the slider of the motor and reduce the frictional resistance during motor operation. The permanent magnet linear motor is embedded on the slider of the long baffles on both sides. A support plate is installed on the upper part of the mover, and a base is fixed on the support plate to facilitate the conversion of the thrust of the mover into the upward or downward motion of the pulley. The short baffles are placed at the upper and lower ends of the permanent magnet linear motor to prevent the mover from slipping.

[0060] The base is a cuboid structure placed at the bottom of the motor. A long baffle is fixed on the base and is U-shaped when viewed from the side. It has grooves for placing the motor's stator permanent magnets and fixing the motor stator.

[0061] In this embodiment, the passive control device includes a hydraulic cylinder 5, a piston rod 6, a gas accumulator 7, and a piston rod position sensor 15. The gas accumulator 7 is composed of an oil-liquid separator, a pressure control unit, and three gas storage cylinders. It provides compensating force when the sea surface waves are small, thus acting as a vibration damper. The oil-gas separator is positioned between the hydraulic cylinder and the gas storage cylinders to separate the oil and gas. The oil-gas separator, pressure control unit, and gas storage cylinders together constitute a gas accumulator 7, giving the structure spring-like characteristics.

[0062] When the ship is subjected to wave-induced heave motion U3, the passive control device compensates for part of the load heave motion. The mother ship heave motion detection unit MRU detects the heave motion of the mother ship 1 in real time and drives the permanent magnet linear motor mover to move in the opposite direction of the mother ship's heave motion through the controller, thereby reducing the oscillation amplitude of the underwater load.

[0063] The hydraulic cylinder consists of a cylinder barrel and a piston, including a rod chamber and a rodless chamber. The rodless chamber is an oil-filled chamber. A position sensor is arranged at the piston rod end to detect the position of the piston rod. The piston end is connected to the base through a hinge to provide passively compensated thrust. The rod chamber is connected to the oil tank through an oil passage. The oil hole at the bottom of the rodless chamber is connected to the oil-gas separator cylinder through an oil passage.

[0064] In some specific implementations, the passive control device also includes an upper end cover, a lower end cover, and a sealed chamber. The two hydraulic cylinders of the passive control device are symmetrically placed on both sides of the pulley with the central axis of the movable pulley as the center line. Each hydraulic cylinder is equipped with an oil-gas separation cylinder, a gas pressure control unit, and three gas storage cylinders.

[0065] The passive control device relies on externally input energy to compensate for the heave motion of the ship lifting heavy objects. It includes a centrally symmetrical permanent magnet linear motor, an incremental sensor for detecting the position of the linear motor mover, a support plate, a base, and a pulley assembly mounted on the mover. The core of the active control device consists of two permanent magnet linear motors, symmetrically mounted on both sides of the pulley support plate, which drive the pulley to reciprocate linearly and provide thrust for active heave compensation. The stator is fixed on the bottom base, and the mover is cast and embedded in a non-magnetic material shell and fixed on the upper guide rail of the long baffle by a slider.

[0066] In this embodiment, the entire compensation system is vertically fixed on the mother ship deck. The movable pulley is placed above the hydraulic cylinder and the permanent magnet linear motor. The compensation stroke of this structure is not limited by space, but only depends on the overall size of the hydraulic cylinder and the motor.

[0067] The core of the drive mechanism of the active control device in this embodiment is a permanent magnet linear motor. The permanent magnet stator is laid on the bottom base, and the mover is embedded in the upper mover support plate. It is installed on the long baffles on both sides through sliders and guide rails, and then fixed on the deck of the mother ship. The motor controller works with the drive circuit to drive the motor mover to drive the moving pulley to reciprocate, providing active heave compensation force. It works together with the passive hydraulic compensation cylinder to achieve semi-active heave compensation.

[0068] In this embodiment, the movable pulley is mounted on the movable pulley base, and the piston rod of the passive compensation cylinder is connected to the movable pulley base through a hinge seat, and is arranged parallel to the linear motor in space.

[0069] The sensing components include a mother ship heave motion detection system and displacement sensors. The mother ship heave motion detection system consists of a motion detection unit and its supporting equipment. The sensor used in the motion detection unit is an accelerometer, which detects the acceleration in the heave direction of the hull and calculates the mother ship's heave displacement through double integration. This signal serves as the tracking compensation input signal for the semi-active heave compensation system. The displacement sensors include a permanent magnet linear motor mover position sensor and a hydraulic cylinder piston rod position sensor. Both the motion detection unit and the displacement sensors are connected to the control system.

[0070] In one or more embodiments, the controller has a built-in power supply to ensure power supply, the mother ship heave detection system and various sensors are connected to the controller, and different algorithms are used for different working conditions to help the controller respond quickly and thus accurately control the load.

[0071] The working method of the high-compensation-precision hybrid semi-active heave compensation system as described above includes: preparation, passive heave compensation mode and active heave compensation mode.

[0072] When the working mode is in the standby mode, only the passive control device is activated and placed in the preset initial state;

[0073] When the working mode is passive heave compensation mode, only the passive control device works;

[0074] When the working mode is switched to semi-active compensation mode, the passive control device and the active control device operate simultaneously.

[0075] When the heave compensation motion of the mother ship caused by the waves is less than or equal to the preset threshold range, the high-compensation-precision hybrid semi-active heave compensation system is put into passive heave compensation mode.

[0076] When the heave compensation motion of the mother ship caused by waves exceeds the preset threshold range, the high-precision hybrid semi-active heave compensation system is put into semi-active compensation mode.

[0077] When a cabled underwater robot / offshore wind turbine is subjected to various external disturbances and rises or falls slightly, the hydraulic cylinder piston will be compressed or stretched due to the inertia of the underwater robot / offshore wind turbine. The passive control device and the underwater robot / offshore wind turbine move up and down with the waves and maintain a relatively uniform speed or descend.

[0078] When underwater robots / offshore wind turbines traverse areas with large waves, to further reduce the impact of waves on their heave motion, the passive control device is first adjusted. The piston rods of the two hydraulic cylinders move up and down with the waves to match the reduced weight of the underwater robot / offshore wind turbine. At this time, the air or nitrogen in the oil-gas separator and gas cylinder provides a buffering effect, further reducing the sudden change in the tension of the steel cable of the underwater robot / offshore wind turbine and preventing the steel cable from breaking due to frequent and drastic changes in tension. At the same time, the active heave compensation mode is activated, the controller and motor drive circuit are turned on, and the motor mover is controlled to run after the mover displacement sensor compares the signal with the mother ship's heave compensation detection device. The mover drives the pulley through the mover transmission rod to further compensate for the heave displacement.

[0079] Specifically, the preparation mode is designed to compensate for the static weight of tethered underwater robots / offshore wind turbines, etc. In this mode, the cable storage winch does not rotate, and one end of the umbilical cable is essentially fixed to the hull. When the working mode is in preparation mode, neither the controller nor the motor drive circuit needs to be activated; only passive compensation of the hydraulic cylinder's movement is required. At this time, the hull remains stationary. Corresponding to different masses of tethered underwater robots / offshore wind turbines, the hydraulic cylinder piston is also at different positions within its stroke. The pneumatic control unit can then regulate the nitrogen pressure between the gas cylinder and the oil-gas separator cylinder. Regulating the gas pressure controls the storage or release of nitrogen from the gas cylinder, causing the piston in the oil-gas separator cylinder to retract or release. This, in turn, brings the hydraulic cylinder piston rod and the motor actuator to the same preset position, thus completing the preparation phase.

[0080] Passive heave compensation technology is mainly based on the working principle of a gas-hydraulic spring. The liquid and gaseous media in the gas accumulator act together on the hydraulic cylinder piston through an oil circuit, giving the structure spring-like characteristics. When the operating mode is passive heave compensation, components such as the controller and motor drive circuit do not need to be activated; only the passive control device needs to operate.

[0081] When the heave motion of the mother ship drives the passive compensation hydraulic cylinder and the moving and fixed pulley block to heave, the piston of the hydraulic cylinder will be compressed or stretched due to inertia. Initially, the motor mover and the hydraulic cylinder piston rod are in the preset position. When the mother ship 1 rises, due to the large inertia of the underwater robot / offshore wind turbine, the equivalent load acting on the passive cylinder piston rod 6 increases, forcing the piston rod to retract and compress the gas in the gas accumulator 7. At the same time, the cable is released. The heave displacement of the tethered underwater robot / offshore wind turbine is passively controlled by the gas accumulator 7. Its compensation relies on the interaction between the gas chamber pressure and the oil chamber pressure of the oil-gas separation cylinder of the gas accumulator 7 to generate the filling and discharging process of the hydraulic cylinder 5.

[0082] When the working mode is switched to semi-active compensation mode, the controller and drive circuit and other components need to be activated. The active and passive control devices act simultaneously. The mother ship heave compensation detection unit (MRU) and the mover displacement sensor generate displacement signals at the same time and send these position signals to the controller. The controller calculates the actual displacement of the mother ship and the actual displacement of the mover based on these signals, calculates the actual load offset, and finally converts the desired displacement adjustment into an electrical signal and sends it to the motor drive circuit to control the direction and magnitude of the linear motor mover, thereby adjusting the displacement deviation of the underwater robot / offshore wind turbine.

[0083] For example, when the initial position is a preset position, the controller calculates the control signal for the drive circuit based on the given signal of the heave compensation from the mother ship heave motion detection unit and the value of the mover position sensor 14. This energizes each phase winding wound around the stator, controlling the mover 9 of the linear motor to reciprocate, thereby counteracting the additional motion caused by the load due to waves. When the mother ship 1 rises, due to the large inertia of the cabled underwater robot / offshore wind turbine, the equivalent load acting on the passive cylinder piston rod 6 increases, causing the piston rod to retract and compress the gas in the gas accumulator 7. Simultaneously, the control and drive components control the mover 9 of the linear motor to move in the direction of piston rod retraction, further retracting the piston rod 6, thereby releasing more cable 18.

[0084] By releasing cable 18 when the mother ship rises due to waves and retrieving cable 18 when it descends, the tension fluctuations of the cable and the oscillation amplitude of the tethered underwater robot / offshore wind turbine, etc., are reduced. When the ship encounters waves and undergoes heave motion, the above process can be repeated cyclically to achieve continuous heave compensation.

[0085] It should be noted that the load connected by the cable can be in the form of other loads besides underwater robots and offshore wind turbines, which will not be described in detail here.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-accuracy hybrid semi-active heave compensation system, characterized in that, It includes a pulley block, a cable storage winch system, an active control device, a passive control device, a control unit, and a sensing component; the pulley block includes a movable pulley and a fixed pulley; the cable storage winch system is connected to one end of the hoisting cable, and the other end of the hoisting cable passes through the movable pulley and the fixed pulley in sequence to connect to the hoisting load; Both the active control device and the passive control device are vertical structures; the movable pulley is located on top of the active control device and the passive control device; in the passive heave compensation mode, the movable pulley can move up and down vertically under the action of the passive control device alone; in the semi-active compensation mode, the movable pulley can move up and down vertically under the combined action of the active control device and the passive control device; the passive control device is used to passively generate a drive signal based on the heave motion of the mother ship to control the movement of the movable pulley. The active control device is a motor, and the passive control device is a hydraulic cylinder; The motor is a permanent magnet linear motor; the permanent magnet linear motor includes a stator permanent magnet, a mover, a three-phase armature winding wound on the mover, and a stator track. The stator permanent magnet is laid at equal intervals on the stator track and arranged alternately according to different polarities. The three-phase winding is assembled inside the mover. The movable pulley is mounted on the movable pulley base, which is connected to the drive end of the passive control device. The movable pulley base is also connected to the transmission base, which is connected to the support plate. The support plate is connected to the guide rail, which is vertically arranged on the outside of the active control device. The support plate can move passively along the guide rail under the action of the drive end of the passive control device or move along the guide rail under the active drive of the active control device. The sensing component is used to sense the heave signal of the mother ship and the displacement signal of the passive control device and transmit them to the control unit. The control unit is used to control the active control device to generate a movement opposite to the heave direction of the mother ship according to the received signals, so as to work together with the passive control device to control the movable pulley to move up and down in the vertical direction.

2. The high-accuracy hybrid semi-active heave compensation system as described in claim 1, characterized in that, The active control device consists of two motors; the passive control device consists of two hydraulic cylinders; wherein, the two linear motors are located inside the two hydraulic cylinders, and the hydraulic cylinders and linear motors are symmetrically placed.

3. The high-accuracy hybrid semi-active heave compensation system as described in claim 1, characterized in that, Two hydraulic cylinders are symmetrically placed on both sides of the moving pulley with the central axis as the center line. Each hydraulic cylinder is equipped with an oil-gas separation cylinder, a pressure control unit and three air storage cylinders.

4. The high-accuracy hybrid semi-active heave compensation system as described in claim 1 or 3, characterized in that, The hydraulic cylinder consists of a cylinder barrel and a piston, including a rod chamber and a rodless chamber. The rodless chamber is an oil-filled chamber. A position sensor is arranged at the piston rod end to detect the position of the piston rod.

5. The high-accuracy hybrid semi-active heave compensation system as described in claim 4, characterized in that, The piston end is connected to the base via a hinge to provide passively compensated thrust. The rod chamber is connected to the oil tank via an oil passage, and the oil hole at the bottom of the rodless chamber is connected to the oil-gas separator via an oil passage.

6. A control method for a hybrid semi-active heave compensation system with high compensation accuracy as described in any one of claims 1-5, characterized in that, include: Preparation work, passive heave compensation mode and active heave compensation mode; When the working mode is in the standby mode, only the passive control device is activated and placed in the preset initial state; When the working mode is passive heave compensation mode, only the passive control device works; When the working mode is switched to semi-active compensation mode, the passive control device and the active control device operate simultaneously.

7. The control method for the high-compensation-accuracy hybrid semi-active heave compensation system as described in claim 6, characterized in that, When the heave compensation motion of the mother ship caused by the waves is less than or equal to the preset threshold range, the high-compensation-precision hybrid semi-active heave compensation system is put into passive heave compensation mode. When the heave compensation motion of the mother ship caused by waves exceeds the preset threshold range, the high-compensation-precision hybrid semi-active heave compensation system is put into semi-active compensation mode.

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