A fish-shaped robot with omnidirectional motion control for deep-sea riser turbulence control

Abstract

A fish-shaped robot with omnidirectional motion control for deep-sea riser current disturbance includes a vibration analysis module and a current disturbance unit. The current disturbance unit includes a fish-shaped fairing and a sensor module mounted on the fairing. One end of the fairing is a flow-splitting tip. The sensor module acquires current ocean current information. A flexible fish tail and a tail fin are connected sequentially behind the fairing. The flexible fish tail includes at least three sequentially connected servos. The servos move independently, mimicking the swaying of a fish tail. The tail fin, similar to a fish fin, sways with the servos. The vibration analysis module analyzes the ocean current information collected by the sensor module and sends control signals to control the servos of the flexible fish tail to sway. The resulting feedback cancels out vortices. This invention achieves flexible tail swaying by rotating three connected servos, simulating the swimming posture of a fish in water. This generates periodically falling vortices, which cancel out the vortices causing vortex-induced vibrations, thus suppressing vortex-induced vibrations.

Description

Technical Field

[0001] This invention relates to the field of marine riser vortex-induced vibration suppression technology, specifically to a fish-shaped robot for omnidirectional motion control of deep-sea riser disturbances. Background Technology

[0002] Vortex-induced vibration suppression technology for marine risers is an important research direction in the field of marine engineering. It aims to reduce fatigue damage to risers under vortex-induced vibration and improve their service life. When ocean currents flow through a riser, vortices are generated at certain flow velocities, causing vortex-induced vibration. When the vortex shedding frequency is close to the natural frequency of the marine riser, the vibration forces the vortex shedding frequency to fix near the structure's natural frequency, resulting in a frequency lock-in phenomenon. This causes strong riser vibration and exacerbates fatigue damage to the riser.

[0003] Vortex-induced vibration (VEM) is one of the main causes of fatigue failure in marine risers. Current methods for suppressing VEM are mostly static, passive suppression structures, which are limited in function, efficiency, and flexibility. Active control methods are a new type of VEM suppression technology developed in recent years. By installing sensors and a control system on the riser, the vibration state can be monitored in real time, and corresponding control measures can be taken to reduce the vibration amplitude based on the vibration information. Active control methods have advantages such as fast response speed and high control accuracy, but currently, they are relatively expensive and technically challenging. Summary of the Invention

[0004] In response to the problems raised in the background art, the present invention provides a fish-like robot to solve them, and the present invention will be further described below.

[0005] A fish-shaped robot with omnidirectional motion control for deep-sea riser current disturbance includes a vibration analysis module and a current disturbance unit. The current disturbance unit includes a fish-shaped fairing and a sensor module mounted on the fairing. One end of the fairing is a flow-splitting tip. The sensor module acquires current ocean current information. A flexible fish tail and a tail fin are connected in sequence behind the fairing. The flexible fish tail includes at least three servo motors connected in sequence. The servo motors move independently to mimic the swaying of a fish tail. The tail fin, similar to a fish fin, sways with the movement of the servo motors. The vibration analysis module analyzes the ocean current information collected by the sensor module and sends control signals to control the servo motors of the flexible fish tail to sway. The resulting feedback cancels out vortices.

[0006] Preferably, the fish-shaped fairing has an integrated automatic control module and a communication module, and the automatic control module is connected to the vibration analysis module through the communication module.

[0007] Preferably, the sensor module includes two sets of ocean current sensors and pressure sensors, which are symmetrically installed on both sides of the diversion tip.

[0008] Preferably, the caudal fin includes a caudal bone and first connecting rods symmetrically pivoted on both sides of the caudal bone. Each first connecting rod is pivotally connected to a second connecting rod. The two second connecting rods are pivotally connected to the same pivot, which is connected to the caudal bone via a variable rod. The surfaces on both sides of the caudal fin are covered with skin.

[0009] Preferably, the variable rod can control the deformation of the tail fin shape by controlling its length. The variable rod includes a sleeve and a thin rod nested in the sleeve. The inner cavity of the sleeve is connected to a high-pressure gas cylinder through a pneumatic pipeline. A solenoid valve is provided on the pneumatic pipeline. Controlling the pressure in the inner cavity of the sleeve can control the overall length of the variable rod. Alternatively, the outer surface of the thin rod and the inner surface of the sleeve are provided with threads. The thin rod and the sleeve are threaded together. The thin rod is controlled by a motor. The rotation of the thin rod can control the overall length of the variable rod.

[0010] Preferably, the fish-shaped robot is attached to the marine riser via a holding assembly. A groove is provided through the fish-shaped fairing, and the holding assembly is located in this groove. The holding assembly consists of two symmetrical parts. Each part includes a base fixedly connected to the fish-shaped fairing. The base has a lead screw inside, and the lead screw has two sliders. The upper and lower parts of the lead screw have opposite thread directions, and the two sliders also have opposite thread directions. Each slider is pivotally connected to a swing arm. One end of each swing arm is connected to a holding ring, and the other ends of the two swing arms are pivotally connected to each other. A climbing roller is provided at this pivot point.

[0011] Preferably, the ferrule is provided with multiple circumferential rollers. When the upper and lower ferrules hold the riser, the circumferential rollers press on the riser, preserving the rotational freedom of the fish-shaped robot relative to the riser. Based on the different pressures on both sides of the diversion tip, it automatically turns to the direction of the ocean current.

[0012] Preferably, the servo is equipped with a tail cover, which is connected to the servo to assist in mimicking the swinging motion of a fish tail.

[0013] Preferably, the servo motor's tail shell surface and the back-flow side of the fish-shaped fairing are provided with micro-lateral grooves, which are perpendicular to the ocean current direction. Under certain flow conditions, the accompanying waves generated by the periodic corrugated surface during navigation produce a row of artificial parallel vortices at the ridge-shaped valleys perpendicular to the incoming flow direction, thereby changing the water flow pattern within the turbulent boundary layer. The sliding friction between the incoming flow and the solid surface is transformed into rolling friction, further reducing drag and noise.

[0014] Preferably, the cross-section of the transverse groove is trigonometric in shape, the wavelength is four times the amplitude, and the wavelength should not exceed 0.2 mm for the best drag reduction effect.

[0015] Preferably, the flexible fishtail outer shell and the fish-shaped fairing have a skin layer on their surface. The skin layer consists of three layers: a rigid layer, a flexible layer, and a protruding layer, from the inside out. The rigid layer is responsible for fixing the shape of the outer shell; the flexible layer is sandwiched between the rigid layer and the protruding layer, which can cleverly absorb and eliminate factors that cause turbulence in the water flow due to stimulation; the transverse grooves are provided on the surface of the protruding layer.

[0016] Beneficial Effects: Compared with existing technologies, this invention has strong adaptability. This solution can autonomously select active and passive vibration suppression modes based on depth and ocean current velocity. Furthermore, the active vibration suppression mode can autonomously adjust the flexible tail oscillation pattern and tail fin shape according to actual application conditions. This invention has high vibration suppression efficiency. In active vibration suppression mode, compared to traditional passive vibration suppression modes, this solution can autonomously adapt to actual application conditions, resulting in higher vibration suppression efficiency. Simultaneously, the specially designed surface microstructures can greatly reduce vortex generation, fundamentally improving vibration suppression efficiency. This invention has strong scalability. By analyzing the collected underwater data, the design of the flexible tail and the tail oscillation scheme can be continuously optimized, allowing for iterative improvements. This invention has good maneuverability. Equipped with a holding component, it can be flexibly arranged on the riser through cluster control and its position adjusted to face the ocean current direction. This invention has good overall integrity, complete overall functions, and a certain degree of self-powering capability, facilitating data acquisition and self-ascent. Attached Figure Description

[0017] Figure 1 : A schematic diagram of the structure of the fish-shaped robot of the present invention;

[0018] Figure 2 : A schematic diagram of the structure of a flexible fish tail and caudal fin;

[0019] Figure 3 : Figure 1 A schematic diagram of the holding component described at point A in the diagram;

[0020] In the diagram: 1. Fish-shaped fairing; 2. Sensor module; 3. Diverter tip; 4. Tail fin; 5. Servo; 6. Tail bone; 7. First link; 8. Second link; 9. Variable rod; 10. Base; 11. Lead screw; 12. Slider; 13. Swing arm; 14. Column clamping ring; 15. Climbing roller; 16. Circumferential roller; 17. Lateral groove; 18. Generating turbine; 19. Tail shell. Detailed Implementation

[0021] Next, we will combine the appendix Figure 1-3 A specific embodiment of the present invention will be described in detail below.

[0022] Reference Appendix Figure 1A fish-shaped robot for omnidirectional motion control in deep-sea riser turbulence control includes a vibration analysis module and a turbulence control unit. The turbulence control unit comprises a fish-shaped fairing 1 and a sensor module 2 mounted on the fairing. The fairing is preferably an integrally formed, streamlined, spindle-shaped structure, resembling a fish in shape. One end of the fairing is a flow-splitting tip 3, located in the direction of the incoming flow from the riser. The sensor module includes two sets of ocean current sensors and pressure sensors, symmetrically mounted on both sides of the flow-splitting tip 3, to acquire the current ocean current velocity and control the turbulence control unit to suppress vortex-induced vibration.

[0023] Reference Appendix Figure 1 and 2 The turbulence-disrupting unit also includes a flexible fishtail and a tail fin 4. The flexible fishtail is connected to the side of the fish-shaped fairing 1 opposite to the splitter tip 3 and includes three sequentially connected servo motors 5, which are linked one by one by clips. The splitter tip 3 is located in the direction of the incoming flow from the riser, while the flexible fishtail is located in the direction of the opposite flow. The independent movement of the three servo motors 5 mimics the swaying of a fishtail to achieve the purpose of active turbulence.

[0024] The caudal fin 4 is connected to the distal servo motor and resembles a fish fin. It is oscillating via the servo motor 5. Different shapes of caudal fins 4 are suitable for different flow velocity environments. In this embodiment, the caudal fin 4 can deform autonomously and is composed of a variable caudal fin skeleton structure, including a caudal bone 6 and first connecting rods 7 symmetrically pivoted on both sides of the caudal bone 6. The first connecting rods 7 are pivotally connected to second connecting rods 8 respectively. The two second connecting rods 8 are pivotally connected to the same pivot axis, which is connected to the caudal bone 6 via a variable rod 9. By controlling the length of the variable rod, the deformation control of the shape of the caudal fin 4 can be achieved.

[0025] In one embodiment, the variable rod 9 includes a sleeve and a thin rod nested inside the sleeve. There are two control methods for this part: one is to control the overall length change of the variable rod by controlling the air pressure inside the sleeve cavity. This requires a high-pressure gas cylinder and a solenoid valve. The high-pressure gas cylinder is connected to the sleeve cavity via a pneumatic pipeline, and the solenoid valve is located on the pneumatic pipeline to control its opening and closing. The other method is through threaded transmission. The outer surface of the thin rod and the inner surface of the sleeve are threaded, and the thin rod and sleeve are threaded together. The thin rod is rotated under the control of a motor, thereby achieving control over the overall length change of the variable rod, and exhibiting excellent stability when operating in the same shape.

[0026] To accommodate different tail fin shapes, the surfaces on both sides of the tail fin are covered with rubber skin.

[0027] Reference Appendix Figure 1 The servo motor 5 is equipped with a tail cover 19, which is connected to the servo motor to assist in mimicking the swinging of a fish tail.

[0028] Reference Appendix Figure 1 and3 The fish-shaped robot is attached to a marine riser via a holding assembly. A groove is provided through the fish-shaped fairing 1, and the holding assembly is located within this groove. The marine riser passes through this groove, and the holding assembly clamps onto the marine riser to stabilize it in the ocean current. The holding assembly consists of two symmetrical parts. Each part includes a base 10 fixedly connected to the fish-shaped fairing 1. A lead screw 11 is built into the base 10, and two sliders 12 are provided on the lead screw 11. The upper and lower parts of the lead screw have opposite thread directions, and the two sliders 12 also have opposite thread directions. A swing arm 13 is pivotally connected to each slider 12. One end of each swing arm 13 is connected to a holding ring 14, and the other ends of the two swing arms 13 are pivotally connected to each other, with a climbing roller 15 provided at this pivot point.

[0029] The lead screw 11 rotates under the drive of the motor. When the lead screw rotates and causes the two sliders to slide towards the center at the same time, the upper and lower retaining rings 14 release the vertical tube, and the middle climbing roller 15 is pressed on the vertical tube. The climbing roller 15 is a power wheel, which uses the friction between the retaining rings 14 and the vertical tube to achieve vertical climbing. When the lead screw rotates and causes the two sliders to slide towards both ends at the same time, the middle climbing roller 15 leaves the vertical tube, and the upper and lower retaining rings 14 hold the vertical tube, fixing the position of the turbulence robot.

[0030] On the drilling platform, all the fish-shaped robots are installed sequentially on the top of the riser. Each time a fish-shaped robot is installed, it is positioned by the gripping component that comes with it, and then the next fish-shaped robot is installed. This process is repeated until all the fish-shaped robots are installed.

[0031] The fish-shaped fairing 1 has a built-in communication module, which enables communication between the fish-like robots and the vibration analysis module of the control platform. Relying on sensors and the communication module, all fish-like robots are controlled through cluster control, allowing them to be evenly distributed on the riser via the holding components.

[0032] The column-holding ring 14 is equipped with multiple circumferential rollers 16. When the upper and lower column-holding rings 14 hold the riser, the circumferential rollers 16 press against the riser, preserving the rotational freedom of the fish-like robot relative to the riser. Based on the different pressures on both sides of the splitting tip, it automatically veers towards the direction of the ocean current. In other words, the holding assembly described in this invention can simultaneously perform multiple actions such as climbing, pipe diameter adaptation and fixation, and robot rotation around the column axis.

[0033] The fish-shaped robot of this invention can autonomously switch turbulence modes based on the ocean current speed measured by its own sensors. Under high current speed, it adopts an active vibration suppression mode; under low current speed, it adopts a passive vibration suppression mode.

[0034] In passive vibration suppression mode, the streamlined profile of the fish-shaped fairing 1 causes the boundary layer separation point to shift backward as the ocean current flows around it, delaying the formation of wake vortices and reducing the wake width. The ocean current generates vortices behind the blunt cylinder (riser). The flexible fishtail swings freely with the water flow, interacting with the vortices in the wake of the blunt cylinder, thus weakening any vortices detached from the riser.

[0035] Reference Appendix Figure 1 Furthermore, the tail shell surface of the servo motor 5 and the back-flow side of the fish-shaped fairing 1 are provided with micro transverse grooves 17. The transverse grooves are perpendicular to the ocean current direction. Under certain flow conditions, the accompanying waves brought up by the periodic corrugated surface during navigation generate a row of artificial parallel vortices at the ridge valley bottom perpendicular to the incoming flow direction, thereby changing the water flow pattern in the turbulent boundary layer. The sliding friction between the incoming flow and the solid surface becomes rolling friction, which further plays the role of drag reduction and noise reduction.

[0036] The cross-section of the transverse groove is trigonometric in shape. Experiments have shown that the drag reduction effect is best when the wavelength is four times the amplitude. At the same time, the wavelength should not exceed 0.2 mm.

[0037] The flexible fishtail's outer shell and fish-shaped fairing 1 have a skin layer on their surface. This skin layer consists of three layers: a rigid layer, a flexible layer, and a protruding layer, from the inside out. The rigid layer is responsible for fixing the shape of the outer shell. The flexible layer, sandwiched between the rigid layer and the protruding layer, can cleverly absorb and eliminate factors that cause turbulence in the water flow due to stimulation. The flexible layer is filled with a highly elastic silicone-like material or a high-viscosity damping fluid, such as silicone oil. The protruding layer is also a surface layer, and the aforementioned transverse grooves are set on the surface of this layer.

[0038] The fish-shaped robot also has a built-in power generation module. Power generation turbines 18 are provided on the fish-shaped fairing 1 at the high-velocity areas on both sides of the splitting tip 3 to convert the kinetic energy of the ocean current into electrical energy. This technology is conventional and will not be further described in this embodiment.

[0039] The fish-shaped fairing 1 also has a built-in automatic control module, which communicates with the vibration analysis module on the drilling platform through the communication module. The vibration analysis module analyzes the water flow signals of different frequencies, amplitudes and phases obtained by the sensor module 2, and combines the experimentally measured time of vortex development and shedding to send a control signal to the automatic control module, which in turn sends a signal to the servo motor 5 of the flexible fish tail behind it, so that the feedback generated by its swing can just cancel out the vortex.

[0040] The active vibration damping function is implemented at high flow rates. In active vibration damping mode, the fish-shaped robot controls the three servo motors 5 at the tail to flexibly swing according to the flow rate data collected by the sensor at the flow tip. At the same time, it can change the shape of the tail fin 4 according to the flow rate. Through the swinging of the flexible fish tail and tail fin 4, the vortex generated in front is destroyed.

[0041] This invention boasts strong adaptability. The proposed solution can autonomously select between active and passive vibration suppression modes based on depth and ocean current velocity. Furthermore, the active vibration suppression mode can autonomously adjust the flexible tail's oscillation pattern and the tail fin's shape according to actual application conditions. This invention offers high vibration suppression efficiency. In active vibration suppression mode, compared to traditional passive modes, this solution can autonomously adapt to actual application conditions, resulting in higher vibration suppression efficiency. Simultaneously, the specially designed surface microstructures can significantly reduce vortex generation, fundamentally improving vibration suppression efficiency. This invention is highly scalable. By analyzing the collected underwater data, the design of the flexible tail and its oscillation scheme can be continuously optimized, allowing for iterative improvements. This invention offers good maneuverability. Equipped with a holding component, it can be flexibly arranged on the riser through cluster control and its position adjusted to face the ocean current direction. This invention has good overall integrity, complete overall functionality, and a certain degree of self-powered capability, facilitating data acquisition and self-ascent.

[0042] 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 fish-shaped robot with omnidirectional motion control for deep-sea riser turbulence control, characterized in that, Includes a vibration analysis module and a turbulence unit; The turbulence unit includes a fish-shaped fairing (1) and a sensor module (2) mounted on the fish-shaped fairing. One end of the fish-shaped fairing (1) is a shunting tip (3). The sensor module (2) acquires current ocean current information. A flexible fish tail and a tail fin (4) are connected in sequence behind the fish-shaped fairing (1). The flexible fish tail includes at least three servo motors (5) connected in sequence. The servo motors (5) move independently to mimic the swaying of the fish tail. The tail fin (4) is similar to a fish fin and sways with the movement of the servo motors (5). The vibration analysis module analyzes the ocean current information collected by the sensor module (2), sends a control signal to control the servo motor (5) of the flexible fish tail to swing, and the resulting feedback cancels out the vortex. The fish-shaped fairing (1) has an automatic control module and a communication module built in it. The automatic control module is connected to the vibration analysis module through the communication module. The sensor module includes an ocean current sensor and a pressure sensor, which are arranged in two sets and symmetrically installed on both sides of the diversion tip (3). The fish-shaped robot is attached to the marine riser via a holding assembly. A groove is provided through the fish-shaped fairing (1), and the holding assembly is located in this groove. The holding assembly consists of two symmetrical parts. Each part includes a base (10) fixedly connected to the fish-shaped fairing (1). A lead screw (11) is built into the base (10). Two sliders (12) are provided on the lead screw (11). The upper and lower parts of the lead screw have opposite thread directions, and the two sliders (12) also have opposite thread directions. A swing arm (13) is pivotally connected to each slider (12). One end of each swing arm (13) is connected to a holding ring (14). The other ends of the two swing arms (13) are pivotally connected to each other, and a climbing roller (15) is provided at this pivot point. Multiple circumferential rollers (16) are provided on the holding ring (14). When the upper and lower holding rings (14) hold the riser, the circumferential rollers (16) press on the riser. The servo motor (5) is provided with a tail shell, which is connected to the servo motor (5) to assist in imitating the swing of a fish tail. The surface of the tail shell and the back-flow side of the fish-shaped fairing (1) provided with micro transverse grooves (17) are provided. The transverse grooves are perpendicular to the ocean current direction. The cross section of the transverse grooves is trigonometric in shape, the wavelength is four times the amplitude, and the wavelength does not exceed 0.2 mm. The flexible fish tail shell and the fish-shaped fairing 1 are provided with a skin layer. The skin layer consists of a rigid layer, a flexible layer and a protruding layer from the inside to the outside. The rigid layer is responsible for fixing the shape of the shell. The flexible layer is sandwiched between the rigid layer and the protruding layer. The transverse groove is provided on the surface of the protruding layer.

2. The omnidirectional motion control fish-shaped robot according to claim 1, characterized in that: The caudal fin (4) includes a caudal bone (6) and first connecting rods (7) pivotally connected symmetrically on both sides of the caudal bone (6). The first connecting rods (7) are respectively pivotally connected to second connecting rods (8). The two second connecting rods (8) are pivotally connected to the same pivot axis, which is connected to the caudal bone (6) through a variable rod (9). The surfaces on both sides of the caudal fin are covered with skin.

3. The omnidirectional motion control fish-shaped robot according to claim 2, characterized in that: The variable rod (9) can control the deformation of the tail fin (4) by controlling its length. The variable rod (9) includes a sleeve and a thin rod nested in the sleeve. The inner cavity of the sleeve is connected to a high-pressure gas cylinder via a pneumatic pipeline. A solenoid valve is installed on the pneumatic pipeline. Controlling the pressure in the inner cavity of the sleeve can control the overall length of the variable rod; or, the outer surface of the thin rod and the inner surface of the sleeve are threaded, the thin rod and the sleeve are threaded together, the thin rod is controlled by a motor, and the rotation of the thin rod can control the overall length of the variable rod.

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