Omnibearing motion control fish-like robot for turbulent flow of deep sea riser

Abstract

The invention discloses an omni-directional motion control fish-like robot for turbulent flow of a deep sea riser. The omni-directional motion control fish-like robot comprises a vibration analysis module and a turbulent flow unit, the turbulent flow unit comprises a fish-shaped fairing and a sensor module arranged on the fish-shaped fairing, one end of the fish-shaped fairing is a shunting tip, and the sensor module obtains current ocean current information; a flexible fishtail and a tail fin are sequentially connected behind the fish-shaped fairing, the flexible fishtail comprises at least three steering engines which are sequentially connected, the steering engines independently act to simulate swinging of the fishtail, and the tail fin is similar to a fin and swings along with action of the steering engines; the vibration analysis module analyzes ocean current information collected by the sensor module and sends out a control signal to control a steering engine of the flexible fishtail to swing, and generated feedback is just counteracted with the vortex. Through rotation of the three connected steering engines, flexible swing of the tail is achieved, the swimming posture of fish in water is simulated, cyclically-falling vortexes can be generated, the vortexes counteract vortexes causing vortex-induced vibration, and the effect of suppressing vortex-induced vibration is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of vortex-induced vibration suppression of marine risers, and in particular to an omnidirectional motion-controlled fish-like robot used for deep-sea riser turbulence. Background Art

[0002] The technology of suppressing vortex-induced vibration of marine risers is an important research direction in the field of marine engineering, which aims to reduce the fatigue damage of risers under the action of vortex-induced vibration and increase their service life. When the ocean current flows through the riser, vortex shedding will occur at a certain flow rate, causing vortex-induced vibration of the riser. When the vortex shedding frequency is close to the natural frequency of the marine riser, the vibration will force the vortex shedding frequency to be fixed near the natural frequency of the structure, resulting in frequency lock-in phenomenon, causing strong riser vibration and aggravating the fatigue damage of the riser.

[0003] Vortex-induced vibration is one of the main causes of fatigue failure of marine risers. Currently, the methods for suppressing vortex-induced vibration are mostly static passive suppression structures with single functions, average efficiency and poor flexibility. Active control method is a new type of vortex-induced vibration suppression technology developed in recent years. By installing sensors and control systems on the riser, the vibration state of the riser can be monitored in real time, and corresponding control measures can be taken according to the vibration information to reduce the vibration amplitude. Active control method has the advantages of fast response speed and high control accuracy, but the cost is relatively high and the technical difficulty is relatively high. Summary of the invention

[0004] According to the problems raised in the background technology, the present invention provides a fish-like robot to solve the problems. The present invention will be further described below.

[0005] A fish-shaped robot with omnidirectional motion control for deep-sea riser spoiler comprises a vibration analysis module and a spoiler unit, wherein the spoiler unit comprises a fish-shaped fairing and a sensor module arranged on the fish-shaped fairing, wherein one end of the fish-shaped fairing is a diverter tip, and the sensor module obtains current ocean current information; a flexible fish tail and a tail fin are sequentially connected behind the fish-shaped fairing, wherein the flexible fish tail comprises at least three sequentially connected steering gears, wherein the steering gears independently act to imitate the swinging of the fish tail, and the tail fins are similar to fish fins and swing with the action of the steering gears; the vibration analysis module analyzes the ocean current information collected by the sensor module, and sends a control signal to control the steering gear of the flexible fish tail to make it swing, and the generated feedback just offsets the vortex.

[0006] Preferably, the fish-shaped fairing has an automatic control module and a communication module built in, and the automatic control module is communicatively connected with the vibration analysis module via the communication module.

[0007] Preferably, the sensor module includes an ocean current sensor and a pressure sensor, which are two groups in total and are symmetrically installed on both sides of the diversion tip.

[0008] Preferably, the tail fin includes a coccyx and first connecting rods symmetrically pivoted on both sides of the coccyx, the first connecting rods are respectively pivoted to second connecting rods, the two second connecting rods are pivoted on the same pivot, and the pivot is connected to the coccyx through a variable rod, and the surfaces on both sides of the tail fin are covered with skin.

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

[0010] Preferably, the fish-like robot is hung on the marine riser through a holding assembly, a column groove is penetrated on the fish-shaped fairing, the holding assembly is arranged in this column groove, the holding assembly includes two symmetrical parts, any part includes a base fixedly connected to the fish-shaped fairing, a lead screw is built in the base, two sliders are provided on the lead screw, the upper and lower parts of the lead screw have opposite thread rotation directions, the thread rotation directions of the two sliders are also opposite, and a swing arm is pivoted on any slider, one end of the swing arm is connected to a column ring, the other ends of the two swing arms are pivoted to each other, and a climbing roller is provided at the pivot point.

[0011] Preferably, the column ring is provided with a plurality of circumferential rollers. When the upper and lower columns embrace the riser, the circumferential rollers press on the riser, retaining the rotational freedom of the fish-like robot relative to the riser, and automatically turning to the direction of the ocean current according to the different pressures on both sides of the diversion tip.

[0012] Preferably, a tail housing is provided outside the servo, and the tail housing is connected to the servo to assist in imitating the swinging of a fish tail.

[0013] Preferably, the tail shell surface provided outside the steering gear and the back flow side of the fish-shaped fairing are provided with micro transverse grooves, which are perpendicular to the direction of the ocean current. Under certain flow conditions, the accompanying waves brought by the periodic corrugated surface during navigation generate a row of artificial parallel vortices at the ridge-shaped valley bottom perpendicular to the incoming flow direction, thereby changing the water flow morphology in the turbulent boundary layer, and the sliding friction between the incoming flow and the solid surface is changed into rolling friction, which further plays a role in reducing drag and noise.

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

[0015] Preferably, the tail shell of the flexible fish tail peripheral and the fish-shaped fairing are provided with a skin layer, which is composed of three layers, namely, a rigid layer, a flexible layer, and a protrusion 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 protrusion layer, and can cleverly absorb and eliminate the factors that cause the chaotic phenomenon of the water flow due to stimulation; the transverse grooves are provided on the surface of the protrusion layer.

[0016] Beneficial effects: Compared with the prior art, the present invention has strong adaptability. The present invention can autonomously select active and passive vibration suppression modes according to the depth and current speed, and the active vibration suppression mode can autonomously adjust the swing mode of the flexible tail and the shape of the tail fin according to the actual application situation. The present invention has high vibration suppression efficiency. In the active vibration suppression mode, the present solution can autonomously adapt to the actual application situation compared with the traditional passive vibration suppression mode, and the vibration suppression efficiency is higher. At the same time, the specially designed surface microstructure can greatly reduce the generation of vortices and fundamentally improve the vibration suppression efficiency. The present invention has strong scalability. By analyzing the collected underwater data, the design of the flexible tail and the swing scheme of the tail are continuously optimized, and the present solution is continuously iterated and optimized. The present invention has good controllability and is equipped with a holding component. It can be flexibly arranged on the riser through cluster control and adjust its own position to face the direction of the ocean current. The present invention has good integrity, complete overall functions and a certain self-powered ability, which creates convenience for data collection and self-climbing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : A schematic structural diagram of the fish-like robot of the present invention; Figure 2 : Schematic diagram of the structure of the flexible fish tail and caudal fin; Figure 3 : Figure 1 A schematic diagram of the structure of the holding assembly shown in FIG. In the figure: a fish-shaped fairing 1, a sensor module 2, a diverter tip 3, a tail fin 4, a servo 5, a coccyx 6, a first connecting rod 7, a second connecting rod 8, a variable rod 9, a base 10, a lead screw 11, a slider 12, a swing arm 13, a column ring 14, a climbing roller 15, a circumferential roller 16, a transverse groove 17, a power generation turbine 18, and a tail casing 19. DETAILED DESCRIPTION

[0018] Next, combine with Figure 1-3 A specific embodiment of the present invention is described in detail.

[0019] Reference Figure 1A fish-shaped robot with omnidirectional motion control for deep-sea riser spoiler, comprising a vibration analysis module and a spoiler unit, wherein the spoiler unit comprises a fish-shaped fairing 1 and a sensor module 2 arranged on the fish-shaped fairing, wherein the fish-shaped fairing is preferably an integrated spindle-shaped streamlined structure, and the whole is similar to a fish shape, and one end of the fish-shaped fairing is a diverter tip 3, and the diverter tip is located in the direction of the riser flow. The sensor module comprises an ocean current sensor and a pressure sensor, which are two groups in total and are symmetrically installed on both sides of the diverter tip 3, to obtain the current ocean current speed, and thereby control the spoiler unit to make it move to achieve the purpose of suppressing vortex-induced vibration.

[0020] Reference Figure 1 and 2 The spoiler unit also includes a flexible fish tail and a tail fin 4. The flexible fish tail is connected to the side of the fish-shaped fairing 1 that is different from the diverter tip 3, and includes three servos 5 connected in sequence. The three servos 5 are connected one by one through buckles. The diverter tip 3 is located in the direction of the flow from the riser, and the flexible fish tail is located in the back direction of the ocean current. The independent actions of the three servos 5 imitate the swing of the fish tail to achieve the purpose of active spoiler.

[0021] The tail fin 4 is connected to the last section of the steering gear, and the whole is similar to a fish fin. The steering gear 5 is used to swing the tail fin 4. The tail fin 4 of different shapes is suitable for different flow rate environments. In this embodiment, the tail fin 4 can be deformed autonomously, and is composed of a skeleton structure of a variable tail fin, including a coccyx 6 and a first connecting rod 7 pivotally connected to the two sides of the coccyx 6 symmetrically. The first connecting rod 7 is pivotally connected to a second connecting rod 8 respectively. The two second connecting rods 8 are pivotally connected to the same pivot. The pivot is connected to the coccyx 6 through a variable rod 9. By controlling the length of the variable rod, the deformation control of the shape of the tail fin 4 can be achieved.

[0022] In one embodiment, the variable rod 9 includes a sleeve and a thin rod nested in the sleeve. There are two schemes for controlling this part: one is to control the air pressure in the cavity of the sleeve to control the change in the overall length of the variable rod. This requires a high-pressure gas cylinder and a solenoid valve. The high-pressure gas cylinder is connected to the inner cavity of the sleeve through a pneumatic pipeline, and the solenoid valve is arranged on the pneumatic pipeline to control the on and off of the pneumatic pipeline; the second is to achieve it through threaded transmission. The outer surface of the thin rod and the inner surface of the sleeve are provided with threads. The thin rod and the sleeve threads cooperate. The thin rod is controlled by a motor to rotate, thereby realizing the change control of the overall length of the variable rod, and the stability when working in the same shape is very good.

[0023] In order to adapt to the different shapes of tail fins, the surfaces on both sides of the tail fin are covered with rubber skin.

[0024] Reference Figure 1 The steering gear 5 is provided with a tail housing 19 outside, and the tail housing is connected to the steering gear to assist in imitating the swing of the fish tail.

[0025] Reference Figure 1 and3 The fish-like robot is hung on the marine riser through a holding assembly. A column slot is provided on the fish-shaped fairing 1. The holding assembly is arranged in the column slot. The marine riser passes through the column slot. The holding assembly is clamped on the marine riser to stabilize in the ocean current. The holding assembly includes two symmetrical parts. Any part includes a base 10 fixedly connected to the fish-shaped fairing 1. The base 10 has a screw 11 built therein. Two sliders 12 are arranged on the screw 11. The upper and lower parts of the screw have opposite thread rotation directions. The thread rotation directions of the two sliders 12 are also opposite. A swing arm 13 is pivoted on any slider 12. One end of the swing arm 13 is connected to a column ring 14. The other ends of the two swing arms 13 are pivoted to each other, and a climbing roller 15 is arranged at the pivot.

[0026] The lead screw 11 rotates under the drive of the motor. When the lead screw rotates to make the two sliders slide toward the center at the same time, the upper and lower column rings 14 release the vertical pipe, and the middle climbing roller 14 is pressed on the vertical pipe. The climbing roller 15 is a power wheel, and the friction between the column ring 14 and the vertical pipe is used to achieve up and down climbing; when the lead screw rotates to make the two sliders slide toward both ends at the same time, the middle climbing roller 15 leaves the vertical pipe, and the upper and lower column rings 14 hold the vertical pipe to fix the position of the spoiler robot.

[0027] All the fish-like robots are installed on the upper end of the riser on the drilling operation platform in turn. Each time one is installed, it is put into place by the holding component of the fish-like robot, and the next fish-like robot is installed at the same time. This process is repeated until all the fish-like robots are installed.

[0028] The fish-shaped fairing 1 has a built-in communication module, through which the fish-shaped robot is connected to the vibration analysis module of the control platform. Relying on the sensor and the communication module, all the fish-shaped robots are controlled by cluster control so that they are evenly distributed on the riser through the holding components.

[0029] The column holding ring 14 is provided with a plurality of circumferential rollers 16. When the upper and lower column holding rings 14 hold the riser, the circumferential rollers 16 press on the riser, retaining the fish-like robot's rotational freedom relative to the riser, and automatically turning to the direction of the ocean current according to the different pressures on both sides of the diversion tip. That is, the holding assembly of the present invention can simultaneously realize multiple actions such as climbing, pipe diameter adaptation and fixation, and robot rotation around the column axis.

[0030] The fish-like robot of the present invention autonomously switches the disturbance mode according to the ocean current speed measured by its own sensor. In the case of high flow rate, the active vibration suppression mode is adopted; in the case of low flow rate, the passive vibration suppression mode is adopted.

[0031] In the passive vibration suppression mode, the streamlined section of the fish-shaped fairing 1, when the ocean current bypasses the fish-shaped fairing 1, the boundary layer separation point migrates backward, delaying the formation of the wake vortex, reducing the wake width, and the ocean current generates a vortex behind the blunt cylinder, i.e., the riser. The flexible fish tail swings freely with the water flow, and the flexible fish tail interacts with the vortex of the blunt cylinder wake to weaken the vortex detached from the riser.

[0032] Reference Figure 1 Furthermore, micro transverse grooves 17 are provided on the tail shell surface outside the steering gear 5 and the dorsal side of the fish-shaped fairing 1. The transverse grooves are perpendicular to the direction of the ocean current. Under certain flow conditions, the accompanying waves brought by the periodic corrugated surface during navigation generate a row of artificial parallel vortices at the ridge-shaped valley bottom perpendicular to the incoming flow direction, thereby changing the water flow pattern in the turbulent boundary layer, and the sliding friction between the incoming flow and the solid surface is converted into rolling friction, which further plays a role in reducing drag and noise.

[0033] The cross section of the transverse groove is in the shape of a trigonometric function. According to tests, 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.

[0034] The tail shell of the flexible fish tail peripheral and the fish-shaped fairing 1 are provided with a skin layer on the surface, which is composed of three layers, namely, a rigid layer, a flexible layer, and a protrusion layer from the inside to the outside. Among them, the rigid layer is responsible for fixing the shape of the shell; the flexible layer is sandwiched between the rigid layer and the protrusion layer, and can cleverly absorb and eliminate the factors that cause the chaotic phenomenon of the water flow due to stimulation. The flexible layer is filled with elastic silicone materials, or uses high-viscosity damping fluid, such as silicone oil; the protrusion layer is also a surface layer, and the aforementioned transverse grooves are set on the surface of this layer.

[0035] The fish-shaped robot also has a built-in power generation module. The fish-shaped fairing 1 is provided with power generation turbines 18 in the high flow velocity areas on both sides of the diverter tip 3 to convert the kinetic energy of the ocean current into electrical energy. This technology is conventional technology and will not be further elaborated in this embodiment.

[0036] The fish-shaped fairing 1 also has a built-in automatic control module, which is connected to 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 time for the vortex to develop and fall off measured experimentally, and sends a control signal to the automatic control module, which sends a signal to the servo 5 of the flexible fish tail at the back, so that the feedback generated by its swing is exactly offset by the vortex.

[0037] Realization of active vibration suppression function at high flow rate. In the active vibration suppression mode, the fish-like robot controls the three servos 5 at the tail to achieve flexible swing according to the flow rate data collected by the sensor on the diverter tip, and at the same time, the shape of the tail fin 4 can be changed according to the flow rate. The vortex generated in front is destroyed by the swing of the flexible fish tail and the tail fin 4.

[0038] The present invention has strong adaptability. The present scheme can autonomously select active and passive vibration suppression modes according to the depth and ocean current speed, and the active vibration suppression mode can autonomously adjust the swing mode of the flexible tail and the shape of the tail fin according to the actual application situation. The present invention has high vibration suppression efficiency. In the active vibration suppression mode, the present scheme can autonomously adapt to the actual application situation compared with the traditional passive vibration suppression mode, and the vibration suppression efficiency is higher. At the same time, the specially designed surface microstructure can greatly reduce the generation of vortices and fundamentally improve the vibration suppression efficiency. The present invention has strong scalability. By analyzing the collected underwater data, the design of the flexible tail and the swing scheme of the tail are continuously optimized, and the present scheme is continuously iterated and optimized. The present invention has good controllability and is equipped with a holding component. It can be flexibly arranged on the riser through cluster control and adjust its own position to face the direction of the ocean current. The present invention has good integrity, complete overall functions and a certain self-power supply capability, which creates convenience for data collection and self-climbing.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fish-like robot with omnidirectional motion control for deep-sea riser disturbance, characterized in that: Includes vibration analysis module and spoiler unit; The spoiler unit comprises a fish-shaped fairing (1) and a sensor module (2) arranged on the fish-shaped fairing, one end of the fish-shaped fairing (1) being a diverter tip (3), and the sensor module (2) acquiring current ocean current information; a flexible fish tail and a tail fin (4) are sequentially connected behind the fish-shaped fairing (1), the flexible fish tail comprising at least three sequentially connected steering gears (5), the steering gears (5) independently acting to imitate the swinging of the fish tail, and the tail fin (4) is similar to a fish fin and swings along with the action of the steering gear (5); The vibration analysis module analyses the ocean current information collected by the sensor module (2), and sends a control signal to control the steering engine (5) of the flexible fish tail to make it swing, so that the generated feedback just cancels out the vortex.

2. The omnidirectional motion controlled fish-like robot according to claim 1, characterized in that: The fish-shaped fairing (1) has an automatic control module and a communication module built in, and the automatic control module is connected to the vibration analysis module through the communication module; the sensor module comprises an ocean current sensor and a pressure sensor, which are two groups in total and are symmetrically installed on both sides of the diverter tip (3).

3. The omnidirectional motion controlled fish-like robot according to claim 1, characterized in that: The tail fin (4) comprises a coccyx (6) and first connecting rods (7) pivotally connected to the coccyx (6) symmetrically on both sides, 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, and the pivot is connected to the coccyx (6) via a variable rod (9), and the surfaces on both sides of the tail fin are covered with skin.

4. The omnidirectional motion controlled fish-like robot according to claim 3, characterized in that: The variable rod (9) can achieve deformation control of the shape of the tail fin (4) by controlling its length, and the variable rod (9) comprises a sleeve and a thin rod embedded in the sleeve; The inner cavity of the sleeve is connected to the high-pressure gas cylinder through a pneumatic pipeline, and a solenoid valve is provided on the pneumatic pipeline. The pressure in the inner cavity of the sleeve can be controlled to control the overall length of the variable rod; or, the outer surface of the thin rod and the inner surface of the sleeve are provided with threads, the thin rod and the sleeve threads are matched, the thin rod is controlled by a motor, and the rotation of the thin rod can control the overall length of the variable rod.

5. The omnidirectional motion controlled fish-like robot according to claim 1, characterized in that: The fish-like robot is hung on a marine riser via a holding assembly. A column slot is provided through the fish-shaped fairing (1). The holding assembly is arranged in the column slot. The holding assembly comprises two symmetrical parts. Any part comprises 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 arranged on the lead screw (11). The upper and lower parts of the lead screw have opposite thread rotation directions. The thread rotation directions of the two sliders (12) are also opposite. Any slider (12) is pivotally connected to a swing arm (13). One end of the swing arm (13) is connected to a column holding ring (14). The other ends of the two swing arms (13) are pivotally connected to each other, and a climbing roller (15) is arranged at the pivoting position.

6. The omnidirectional motion controlled fish-like robot according to claim 5, characterized in that: The column holding ring (14) is provided with a plurality of circumferential rollers (16); when the upper and lower column holding rings (14) hold the vertical pipe, the circumferential rollers (16) are pressed against the vertical pipe.

7. The omnidirectional motion controlled fish-like robot according to claim 1, characterized in that: The steering gear (5) is provided with a tail housing outside, and the tail housing is connected to the steering gear (5) to assist in imitating the swinging of a fish tail.

8. The omnidirectional motion controlled fish-like robot according to claim 7, characterized in that: Micro transverse grooves (17) are provided on the surface of the tail shell provided outside the steering gear (5) and on the backstream side of the fish-shaped fairing (1), and the transverse grooves are perpendicular to the direction of the ocean current.

9. The omnidirectional motion controlled fish-like robot according to claim 8, characterized in that: The cross section of the transverse groove is in the shape of a trigonometric function, the wavelength is four times the amplitude, and the wavelength does not exceed 0.2 mm.

10. The omnidirectional motion controlled fish-like robot according to claim 1, characterized in that: The tail shell of the flexible fishtail peripheral and the fish-shaped fairing 1 are provided with skin layers on their surfaces. The skin layers are respectively a rigid layer, a flexible layer, and a protrusion layer from the inside to the outside. The rigid layer is responsible for fixing the shape of the outer shell, and the flexible layer is sandwiched between the rigid layer and the protrusion layer. The transverse grooves are provided on the surface of the protrusion layer.

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