Pneumatic pitch drive system and method for underwater semi-active flapping wing power generation device

Abstract

This invention discloses a pneumatic pitch drive system and method for an underwater semi-active flapping fin power generation device, belonging to the field of fluid energy conversion technology. The system includes a mounting frame, an air supply module, and a motion module. The motion module includes flapping fins and a pitch drive assembly, which comprises dual pneumatic chambers, a piston-rack assembly, gears, and an angle detection element. The air supply module is separate from the motion module and includes an air source and valve group for independently controlling the air supply and exhaust of the dual pneumatic chambers. The controller adjusts the pressure difference between the two chambers according to the deviation between the actual pitch angle and the target pitch angle, driving the piston-rack assembly to reciprocate, and driving the flapping fins to pitch motion via the gears, forming a closed-loop control. This invention reduces the use of underwater electrical components, lowers the risk of seal failure and corrosion, and overcomes the response lag and motion overshoot problems caused by the compressibility of gas through closed-loop control, improving the stability of pitch control and energy harvesting efficiency.

Description

Technical Field

[0001] This invention relates to the field of fluid energy conversion technology, specifically to a pneumatic pitch drive system and method for an underwater semi-active flapping wing power generation device. Background Technology

[0002] With the increasing demand for low-speed hydrodynamic energy development, such as ocean and river energy, flapping-wing energy harvesting devices are attracting widespread attention due to their excellent adaptability in low-velocity and complex flow fields. In underwater semi-active flapping-wing power generation devices, the pitching motion of the flapping wing is usually directly driven by motors, servo motors, or servo drives. These electrical actuators can achieve high control precision and response speed, facilitating the implementation of complex motion laws such as sinusoidal oscillation or specified angle tracking through preset programs, thereby optimizing the hydrodynamic performance of the flapping wing. However, when these electrical drive components are directly deployed in the underwater environment, their long-term operation faces severe challenges. Because underwater sealing technology cannot completely prevent water molecule penetration, seal failures are prone to occur at motor and wiring joints, leading to problems such as water ingress short circuits, accelerated insulation aging, and electrochemical corrosion. More importantly, the reliability of the transmission mechanism and power supply signal lines of these electrical components will significantly decrease when subjected to periodic hydrodynamic torques and mechanical shocks. Once a failure occurs, not only are repair costs high, but salvage and replacement operations are also extremely difficult, severely restricting the overall service life and commercial feasibility of the device.

[0003] To mitigate the safety hazards of underwater electric drives, some flapping-wing energy harvesting devices have adopted a fluid pressure drive system. This involves placing the air compressor and control valve assembly, along with other electrical components, above the water surface, and transmitting power to the underwater actuators via air pipelines. While this approach reduces the number of electrically connected underwater components, conventional pneumatic systems often employ on / off directional valve control. The compressibility of gas itself easily leads to motion response lag, overshoot, and amplitude deviation, making it difficult to achieve continuous, smooth, and precise closed-loop control of the flapping wing's pitch angle. Ultimately, this affects the optimal phase matching between the flapping wing's pitch and buoyancy movements, thus reducing energy conversion efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a pneumatic pitch drive system and method for an underwater semi-active flapping wing power generation device to solve the above-mentioned problems.

[0005] The technical solution of this invention is: A pneumatic pitch drive system for an underwater semi-active flapping-wing power generation device includes: a mounting base fixed in an underwater environment; and a motion module mounted on the mounting base and capable of floating and sinking along the mounting base. The motion module includes flapping wings and a pitch drive assembly. The pitch drive assembly includes: a first pneumatic chamber, a second pneumatic chamber, a piston-rack assembly, a gear, and an angle detection element. The first and second pneumatic chambers are coaxially arranged. The piston-rack assembly is disposed between the first and second pneumatic chambers and includes a first piston, a second piston, and a rack connecting the two pistons. The first and second pistons are slidably disposed within the first and second pneumatic chambers, respectively. The gear and the rack... The system is engaged and connected to the flapping wing drive assembly; the angle detection element is used to detect the actual pitch angle of the flapping wing; the air supply module is separately set from the motion module and connected to the pitch drive assembly through a pipeline, and the air supply module is set above the water surface or on the shore; the air supply module includes an air source and a valve group, the valve group is used to independently control the air supply and exhaust of the first air pressure chamber and the second air pressure chamber; the controller is communicatively connected to the angle detection element and the valve group, the controller controls the valve group according to the deviation between the actual pitch angle and the target pitch angle, so as to adjust the pressure difference between the first air pressure chamber and the second air pressure chamber, drive the piston-rack assembly to reciprocate, and drive the flapping wing to pitch through the gear, forming a closed-loop control.

[0006] Furthermore, the pitch drive assembly also includes: multiple pressure sensors, respectively disposed on the first and second pressure chambers, for collecting pressure signals in the two pressure chambers; each pressure sensor is communicatively connected to the controller, which determines the target pressure difference based on the actual pitch angle, the target pitch angle, and the pressure signals of the two pressure chambers, and then controls the valve group to adjust the actual pressure difference between the first and second pressure chambers.

[0007] Furthermore, the air supply module also includes: a pressure stabilizing chamber, which is connected to the air source via a connecting pipe; an air inlet pipe and an air outlet pipe, both of which are flexible pipes used to generate adaptive bending deformation when the motion module performs buoyancy motion; the air inlet pipe is configured with two paths, which are respectively connected from the pressure stabilizing chamber to the first air pressure chamber and the second air pressure chamber; the air outlet pipe is configured with two paths, which are respectively led out from the first air pressure chamber and the second air pressure chamber, with the end being an exhaust port.

[0008] Furthermore, the valve assembly includes: a first pressure regulating valve, a second pressure regulating valve, a first exhaust valve, and a second exhaust valve; the first pressure regulating valve and the second pressure regulating valve are respectively disposed on the two intake pipes and are used to control the air supply to the first air pressure chamber and the second air pressure chamber respectively; the first exhaust valve and the second exhaust valve are respectively disposed on the two exhaust pipes and are used to control the exhaust from the first air pressure chamber and the second air pressure chamber respectively.

[0009] Furthermore, the controller is configured as follows: When the flapping wings need to pitch in the first direction, the first pressure regulating valve is controlled to increase the air supply pressure to increase the pressure of the first air chamber, and the second exhaust valve is controlled to open or the second pressure regulating valve is controlled to decrease the air supply pressure to reduce the pressure of the second air chamber, so that the pressure of the first air chamber is greater than the pressure of the second air chamber. When the flapping wings need to pitch in the second direction, the second pressure regulating valve is controlled to increase the air supply pressure to increase the pressure of the second air chamber, and the first exhaust valve is controlled to open or the first pressure regulating valve is controlled to decrease the air supply pressure to reduce the pressure of the first air chamber, so that the pressure of the second air chamber is greater than the pressure of the first air chamber.

[0010] Furthermore, the mounting base includes: a water platform, a sliding rail reinforcing rib, and a base. The sliding rail is vertically positioned between the water platform and the base, and the reinforcing rib connects the water platform and the base to enhance the structural stability of the mounting base. The motion module also includes: two pneumatic chamber clamps, respectively fitted onto the outside of the first and second pneumatic chambers, and the two pneumatic chamber clamps are fixedly connected by a connecting rod to fix the first and second pneumatic chambers together; and two sliders, respectively fixedly mounted on the two pneumatic chamber clamps and slidingly engaged with the sliding rail to achieve the buoyancy motion of the motion module.

[0011] Furthermore, the gas supply module also includes an air filter and a pressure reducing valve; the air filter and the pressure reducing valve are disposed on the connecting pipe between the pressure stabilizing chamber and the gas source, the outlet of the gas source is sequentially connected to the air filter, the pressure reducing valve and the pressure stabilizing chamber, and the outlet of the pressure stabilizing chamber is connected to the first pressure regulating valve and the second pressure regulating valve respectively.

[0012] Furthermore, the angle detection element is an absolute angle encoder, which is mounted on the connecting shaft between the gear and the flapping wing.

[0013] A pneumatic pitch drive method for an underwater semi-active flapping-wing power generation device, implemented using the above-mentioned system, includes the following steps: Generate the target pitch angle signal for flapping wings; The actual pitch angle of the flapping wing is collected in real time by the angle detection element and fed back to the controller; The controller adjusts the air supply and exhaust states of the first and second air pressure chambers independently through the valve group according to the deviation between the target pitch angle and the actual pitch angle, so as to change the pressure difference between the two air pressure chambers. The piston-rack assembly is driven to reciprocate by the pressure difference, and the flapping wings are driven to pitch through the meshing of the rack and gear. By repeatedly collecting data from the angle detection element, adjusting the controller, and driving the piston-rack assembly, the actual pitch angle of the flapping wing continuously tracks the target pitch angle, forming a closed-loop control.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention separates the air supply module and motion module and places them outside the underwater environment. It transmits pneumatic power to the underwater pitch drive component only through pipelines, avoiding the need to arrange electrical drive components such as motors and servos underwater. This effectively reduces the risk of equipment failure caused by seal failure, water ingress short circuits and corrosion damage, and improves the safety and reliability of the device in long-term operation. Simultaneously, the pressure difference between the first and second air pressure chambers drives the piston-rack assembly to reciprocate. The linear motion is converted into the reciprocating pitch motion of the flapping wing through the meshing of the gear and rack. The pure pneumatic actuator replaces the traditional underwater electrical actuator, avoiding electrical hazards at the underwater dynamic seals. Moreover, the controller can independently adjust the air supply and exhaust states of the two air pressure chambers through the valve group based on the deviation between the actual pitch angle and the target pitch angle fed back by the angle detection element in real time. This real-time correction of the pressure difference between the two chambers forms an angle closed-loop control, effectively overcoming the response lag and motion overshoot problems caused by the compressibility of gas. This allows the actual pitch angle of the flapping wing to accurately and stably track the target pitch angle, ensuring the best phase matching between the pitch motion and the buoyancy motion, thereby improving the energy harvesting efficiency and operational stability of the underwater semi-active flapping wing power generation device. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0016] Figure 2 This is a schematic diagram of the mounting base of the present invention.

[0017] Figure 3 This is a schematic diagram of the motion module of the present invention.

[0018] Figure 4 This is a schematic diagram of the pitch drive assembly of the present invention.

[0019] Figure 5 This is a schematic diagram of the structure of the pneumatic chamber clamp of the present invention.

[0020] Figure 6 This is a schematic diagram of the piston-rack assembly of the present invention.

[0021] Figure 7 This is a cross-sectional view of the air pressure chamber and its internal structure.

[0022] Figure 8 This is a schematic diagram of the gas supply module.

[0023] The components include: 1. Mounting frame; 1a. Floating platform; 1b. Slide rail; 1c. Reinforcing rib; 1d. Base; 2. Air supply module; 3. Motion module; 4. Flapping wing; 5. Pitch drive assembly; 6. Air intake pipe; 7. Exhaust pipe; 8. First air pressure chamber; 9. Second air pressure chamber; 10. Pressure sensor; 11. Angle detection element; 12. Air pressure chamber clamp; 13. Slider structure; 14. First piston; 15. Second piston; 16. Rack; 17. Gear; 18. Air source; 19. Air filter; 20. Pressure reducing valve; 21. Pressure stabilizing chamber; 22. First pressure regulating valve; 23. Second pressure regulating valve; 24. First exhaust valve; 25. Second exhaust valve. Detailed Implementation

[0024] The following is combined with Figures 1 to 8 The specific embodiments of the present invention will be described in detail below. In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] It should be noted that the circuit connections involved in this invention all adopt conventional circuit connection methods and do not involve any innovation.

[0027] Example like Figure 1 and Figure 2As shown, this embodiment of a pneumatic pitch drive system for an underwater semi-active flapping wing power generation device includes: a mounting base 1, an air supply module 2, and a motion module 3. The mounting base 1, as the main load-bearing structure of the entire device, is fixedly arranged underwater to provide a guiding foundation for the floating and sinking movement of the motion module 3. The mounting base 1 includes a surface platform 1a, slide rails 1b, reinforcing ribs 1c, and a base 1d; wherein, the surface platform 1a is located on the upper part of the mounting base 1 and is used to install and support the air supply module 2; the base 1d is located on the lower part of the mounting base 1 and is used to improve the support stability of the device when arranged underwater; four slide rails 1b are vertically connected between the surface platform 1a and the base 1d, and are used to cooperate with the slider structure 13 on the motion module 3, enabling the motion module 3 to float and sink along the slide rails 1b; the reinforcing ribs 1c are located between the surface platform 1a and the base 1d to enhance the overall rigidity and deformation resistance of the mounting base 1, thereby ensuring the guiding stability of the motion module 3 during the floating and sinking process. The air supply module 2 is arranged on the water platform 1a, or it can be set on the shore as needed, and is connected to the pitch drive component 5 in the motion module 3 through a pipeline; the motion module 3 is installed on the slide rail 1b and can perform reciprocating floating motion along the slide rail 1b under the action of fluid.

[0028] like Figure 3 , Figure 4 and Figure 5 As shown, the motion module 3 is mounted on the mounting base 1 and can perform floating and sinking movements along the mounting base 1. The motion module 3 mainly includes a flapping wing 4 and a pitch drive assembly 5. The flapping wing 4 is connected to the pitch drive assembly 5, which drives the flapping wing 4 to perform reciprocating pitch movements around the pitch axis. The pitch drive assembly 5 includes a first air pressure chamber 8 and a second air pressure chamber 9 arranged coaxially opposite to each other, a piston-rack assembly, a gear 17, and an angle detection element 11. The first air pressure chamber 8 and the second air pressure chamber 9 are fixedly connected by a central connecting structure to form a symmetrically arranged double air pressure chamber structure. The piston-rack assembly is located between the first air pressure chamber 8 and the second air pressure chamber 9 and includes a first piston 14, a second piston 15, and a rack 16 connected between the two pistons. The first piston 14 and the second piston 15 are slidably disposed in the first air pressure chamber 8 and the second air pressure chamber 9, respectively. The gear 17 meshes with the rack 16 and is drivenly connected to the flapping wing 4. The angle detection element 11 is used to detect the actual pitch angle of the flapping wing 4. Each pressure chamber is equipped with a pressure sensor 10, which is used to detect the pressure signal in the corresponding pressure chamber in real time, providing feedback for the adjustment of the pressure difference between the two pressure chambers. Each pressure sensor 10 is communicatively connected to the controller. The controller determines the target pressure difference based on the target pitch angle, the actual pitch angle, and the pressure signals from the two pressure chambers, and then controls the valve group to adjust the actual pressure difference between the first pressure chamber 8 and the second pressure chamber 9, thereby realizing a dual closed-loop control combining angle feedback and pressure feedback.

[0029] like Figure 8 As shown, the air supply module 2 is installed on the water platform 1a above the mounting base 1 (or can be installed on the shore as needed) to provide compressed air to the pitch drive assembly 5 in the underwater motion module 3, and to control the air supply and exhaust process of the first air pressure chamber 8 and the second air pressure chamber 9.

[0030] The gas supply module 2 also includes a pressure stabilizing chamber 21, which is connected to the gas source 18 via a connecting pipe. The pressure stabilizing chamber 21 is used to buffer pressure fluctuations during the gas supply process and to provide a relatively stable inlet pressure for the subsequent pressure regulating valve.

[0031] Both the intake pipe 6 and the exhaust pipe 7 are flexible pipes designed to adapt to the floating and sinking motion of the motion module 3. The intake pipe 6 has two branches, connecting from the pressure stabilizing chamber 21 to the first pressure chamber 8 and the second pressure chamber 9, respectively. The exhaust pipe 7 also has two branches, leading out from the first pressure chamber 8 and the second pressure chamber 9, with exhaust ports at their ends. Because the motion module 3 can float and sink along the slide rail 1b under the influence of fluid, the flexible pipes can adapt to the vertical movement of the motion module 3, thus avoiding additional constraints on the floating and sinking motion of the motion module 3 by the air pipes and ensuring the continuity of air supply and exhaust processes in the pressure chambers.

[0032] like Figure 8 As shown, the valve assembly includes a first pressure regulating valve 22, a second pressure regulating valve 23, a first exhaust valve 24, and a second exhaust valve 25. The first pressure regulating valve 22 and the second pressure regulating valve 23 are respectively installed on two intake pipes 6, used to control the supply pressure of the first pressure chamber 8 and the second pressure chamber 9, respectively. By controlling the output pressure of the first pressure regulating valve 22 and the second pressure regulating valve 23, a pressure difference of different magnitudes and directions can be formed between the first pressure chamber 8 and the second pressure chamber 9, thereby driving the piston-rack assembly to reciprocate. The first exhaust valve 24 and the second exhaust valve 25 are respectively installed on two exhaust pipes 7, used to control the exhaust pressure reduction of the first pressure chamber 8 and the second pressure chamber 9, respectively. When it is necessary to reduce the pressure in a certain pressure chamber, the controller controls the corresponding exhaust valve to open, allowing the gas in that pressure chamber to be discharged through the exhaust pipe 7; when it is necessary to maintain the pressure in a pressure chamber, the corresponding exhaust valve closes to maintain the pressure state of that pressure chamber.

[0033] The controller is communicatively connected to the angle detection element 11, the pressure sensor 10, and the valve group. During operation, the controller adjusts the working states of the first pressure regulating valve 22, the second pressure regulating valve 23, the first exhaust valve 24, and the second exhaust valve 25 according to the pressure signals collected by the pressure sensors 10 in the first and second pressure chambers 8 and 9, and the actual pitch angle signal of the flapping wing 4 collected by the angle detection element 11.

[0034] When the flapping wing 4 needs to pitch in the first direction, the controller controls the first pressure regulating valve 22 to increase the air supply pressure to raise the pressure in the first air pressure chamber 8, and controls the second exhaust valve 25 to open or controls the second pressure regulating valve 23 to decrease the air supply pressure to lower the pressure in the second air pressure chamber 9, so that the pressure in the first air pressure chamber 8 is greater than the pressure in the second air pressure chamber 9. When the flapping wing 4 needs to pitch in the second direction, the controller controls the second pressure regulating valve 23 to increase the air supply pressure to raise the pressure in the second air pressure chamber 9, and controls the first exhaust valve 24 to open or controls the first pressure regulating valve 22 to decrease the air supply pressure to lower the pressure in the first air pressure chamber 8, so that the pressure in the second air pressure chamber 9 is greater than the pressure in the first air pressure chamber 8. When the flapping wing 4 approaches the target pitch angle, the controller reduces the air supply or closes the corresponding exhaust valve to stabilize the pressure in both air pressure chambers, thereby achieving closed-loop regulation of the flapping wing 4's pitch angle.

[0035] like Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, the mounting base 1 includes a water platform 1a, a slide rail 1b, a reinforcing rib 1c, and a base 1d. The slide rail 1b is vertically positioned between the water platform 1a and the base 1d, and the reinforcing rib 1c connects the water platform 1a and the base 1d to enhance the overall rigidity and deformation resistance of the mounting base 1, thereby ensuring the guiding stability of the motion module 3 during the floating and sinking process.

[0036] The motion module 3 also includes two pneumatic chamber clamps 12 and two sliders 13. The two pneumatic chamber clamps 12 are respectively fitted onto the outside of the first pneumatic chamber 8 and the second pneumatic chamber 9, and are fixedly connected by a connecting rod to securely connect the first pneumatic chamber 8 and the second pneumatic chamber 9. The two sliders 13 are respectively fixedly mounted on the two pneumatic chamber clamps 12 and slide in cooperation with the slide rail 1b to realize the floating and sinking movement of the motion module 3. The pneumatic chamber clamps 12 serve two purposes: firstly, to connect and fix the first pneumatic chamber 8, the second pneumatic chamber 9, and the sliders 13; secondly, to enhance the lateral support and limiting function of the pitch drive assembly 5, thereby improving the motion stability and guiding reliability of the motion module 3 during the floating and sinking process.

[0037] like Figure 8As shown, the air supply module 2 also includes an air filter 19 and a pressure reducing valve 20. The air filter 19 and pressure reducing valve 20 are located on the connecting pipe between the pressure regulating chamber 21 and the air source 18. The air source 18 is an air compressor used to supply compressed air to the entire air circuit system. The outlet of the air source 18 is sequentially connected to the air filter 19, the pressure reducing valve 20, and the pressure regulating chamber 21. The air filter 19 is used to remove moisture, oil mist, and particulate impurities from the compressed air to improve the operational stability of subsequent air circuit components. The pressure reducing valve 20 is used to adjust the higher pressure gas output from the air source 18 to a pressure range suitable for the operation of the pitch drive assembly 5. The outlet of the pressure regulating chamber 21 is connected to the first pressure regulating valve 22 and the second pressure regulating valve 23, respectively, to provide stable and independently adjustable compressed air to the two intake pipes 6.

[0038] like Figure 6 and Figure 7 As shown, the angle detection element 11 is disposed on the connecting shaft between the gear 17 and the flapping wing 4. In this embodiment, the angle detection element 11 is an absolute angle encoder. A symmetrical annular hole structure is provided in the central area of ​​the connection between the first air pressure chamber 8 and the second air pressure chamber 9. The annular hole structure is used to install the absolute angle encoder, so that the absolute angle encoder can be arranged between the pitch transmission structure and the flapping wing 4. Connecting shafts extending outward are respectively provided on the left and right sides of the gear 17. The connecting shafts pass through the absolute angle encoder disposed at the air pressure chamber connection and are connected to the flapping wing 4 through a coupling. The absolute angle encoder is used to detect the actual pitch angle signal transmitted from the gear 17 to the flapping wing 4 in real time and feeds the angle signal back to the controller. Through the above structure, the pressure difference between the first air pressure chamber 8 and the second air pressure chamber 9 can be sequentially converted into the linear motion of the piston-rack assembly, the rotational motion of the gear 17, and the pitch motion of the flapping wing 4, thereby realizing pneumatic pitch drive.

[0039] This embodiment also provides a pneumatic pitch drive method for an underwater semi-active flapping wing power generation device. This method is based on the above system, and its specific process is as follows: First, a target pitch angle signal is generated based on the target motion law of the flapping wing 4. The target pitch angle can be a fixed angle control signal or a periodic pitch angle signal that varies with time. For example, during periodic flapping wing energy harvesting, the target pitch angle signal can be generated based on the set pitch amplitude, pitch frequency, and phase parameters.

[0040] Secondly, the actual pitch angle of the flapping wing 4 is acquired in real time by the angle detection element 11 and fed back to the controller. Simultaneously, pressure sensors 10, respectively installed on the first and second pressure chambers 8 and 9, acquire the pressure signals within the two chambers in real time and feed them back to the controller. Based on the deviation between the target pitch angle and the actual pitch angle, and combined with the real-time pressure status of the two chambers, the controller determines the required target pressure difference between the first and second pressure chambers 8 and 9. According to the target pressure difference, the controller independently adjusts the air supply and exhaust states of the first and second pressure chambers 8 and 9 through valve groups to change the pressure difference between the two chambers.

[0041] When the controller determines that the flapping wing 4 needs to pitch in the first direction, the controller controls the first pressure regulating valve 22 to increase the air supply pressure to increase the pressure in the first air pressure chamber 8, and controls the second exhaust valve 25 to open or controls the second pressure regulating valve 23 to decrease the air supply pressure to decrease the pressure in the second air pressure chamber 9, so that the pressure in the first air pressure chamber 8 is greater than the pressure in the second air pressure chamber 9. At this time, the pressure difference formed between the first air pressure chamber 8 and the second air pressure chamber 9 pushes the piston-rack assembly to move in the corresponding direction, and the rack 16 drives the gear 17 to rotate, thereby causing the flapping wing 4 to pitch in the first direction.

[0042] When the controller determines that the flapping wing 4 needs to pitch in the second direction, the controller controls the second pressure regulating valve 23 to increase the air supply pressure to increase the pressure in the second air pressure chamber 9, and controls the first exhaust valve 24 to open or controls the first pressure regulating valve 22 to decrease the air supply pressure to reduce the pressure in the first air pressure chamber 8, so that the pressure in the second air pressure chamber 9 is greater than the pressure in the first air pressure chamber 8. At this time, the piston-rack assembly moves in the opposite direction under the action of the reverse pressure difference, and the rack 16 drives the gear 17 to rotate in the opposite direction, thereby driving the flapping wing 4 to pitch in the second direction.

[0043] When the actual pitch angle of the flapping wing 4 is close to the target pitch angle, the controller reduces the pressure difference between the two air chambers based on the angle deviation and the pressure signals of the two air chambers, or controls the corresponding pressure regulating valve and exhaust valve to enter the pressure holding state, thereby reducing the movement speed of the piston-rack assembly and reducing the pitch overshoot of the flapping wing 4. If the actual pitch angle exceeds the target pitch angle, the controller adjusts the pressure difference between the first air chamber 8 and the second air chamber 9 in the opposite direction to correct the flapping wing 4 towards the target pitch angle.

[0044] The above-mentioned steps of acquiring data from the angle detection element 11, adjusting the controller, and driving the piston-rack assembly are repeated to ensure that the actual pitch angle of the flapping wing 4 continuously tracks the target pitch angle. As a result, the pressure difference between the first air chamber 8 and the second air chamber 9 is adjusted in real time, the piston-rack assembly generates reciprocating linear motion, and the gear 17 converts the linear motion into reciprocating rotational motion, ultimately realizing the closed-loop pneumatic pitch drive of the flapping wing 4.

[0045] Through the above control method, this embodiment can adjust the air supply and exhaust process of the two air chambers in real time according to the actual pitch state of the flapping wing 4 and the pressure state of the two air chambers. This makes the air pressure difference drive process no longer rely on simple on / off switching control, but forms a closed-loop control mode that combines angle feedback and pressure feedback, thereby improving the stability, adjustability and tracking accuracy of the flapping wing pitch motion.

[0046] It should be noted that this embodiment mainly focuses on the active drive and closed-loop control of the flapping wing pitch direction in an underwater semi-active flapping wing power generation device. The key is to achieve controllable adjustment of the flapping wing pitch angle through dual-pressure chamber differential drive, piston-rack-gear transmission, pressure feedback, and angle feedback. For the buoyancy motion generated by the motion module 3 along the slide rail 1b, its energy harvesting method can be configured according to actual application requirements. For example, the reciprocating buoyancy motion of the motion module 3 can be converted into the rotational motion of the generator rotor through a rack and pinion mechanism, pulley mechanism, crank-connecting rod mechanism, or other linear-rotation conversion mechanism, thereby realizing the conversion of mechanical energy in the buoyancy direction into electrical energy. The above-mentioned buoyancy energy harvesting mechanism can be used in conjunction with the closed-loop pneumatic pitch drive system of this embodiment, but it does not affect the limitations of this embodiment on the flapping wing pitch drive method and its control method.

[0047] In this embodiment, the pressure difference between the two air chambers is mainly used to generate the driving force for the piston-rack assembly, and then converts the linear motion into the pitch rotation of the flapping fin through the meshing relationship between the rack and gear. Therefore, from the perspective of the ideal mechanism, the pressure difference first corresponds to the driving force on the piston. After being transmitted through the rack and gear, the driving force forms a driving torque acting on the pitch axis, and the pitch angle is the result of the combined effects of the driving torque, mechanism friction, sealing resistance, air compressibility, pipeline hysteresis, and control feedback.

[0048] Therefore, for a specific device structure and specific operating conditions, the correspondence or control parameters between pressure difference and pitch angle response can be obtained through experimental calibration or debugging. For example, an empirical mapping relationship between target pressure difference, actual pressure difference and actual pitch angle can be established for subsequent controller parameter tuning.

[0049] This embodiment does not limit itself to a specific algorithm. In actual implementation, different control methods can be selected based on the device size, air chamber volume, flapping wing load, motion frequency, and target control accuracy, such as proportional control, PID control, feedforward plus feedback control, or control methods based on calibration tables.

[0050] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A pneumatic pitch drive system for an underwater semi-active flapping wing power generation device, characterized in that, include: Mounting base frame, fixed in the underwater environment; A motion module, mounted on the mounting base and capable of floating along the mounting base, includes flapping wings and a pitch drive assembly; The pitch drive assembly includes: a first air chamber, a second air chamber, a piston-rack assembly, a gear, and an angle detection element; the piston-rack assembly is disposed between the first and second air chambers, and includes a first piston, a second piston, and a rack connecting the two pistons, with the first and second pistons slidably disposed within the first and second air chambers respectively; the gear meshes with the rack and is drively connected to the flapping wing; the angle detection element is used to detect the actual pitch angle of the flapping wing; The air supply module is separately set from the motion module and is connected to the pitch drive assembly through a pipeline; the air supply module includes an air source and a valve group, the valve group being used to independently control the air supply and exhaust of the first and second air pressure chambers; The controller is communicatively connected to the angle detection element and the valve group. The controller controls the valve group according to the deviation between the actual pitch angle and the target pitch angle to adjust the pressure difference between the first air chamber and the second air chamber, drive the piston-rack assembly to reciprocate, and drive the flapping wing to pitch through the gear, forming a closed-loop control.

2. The pneumatic pitch drive system for an underwater semi-active flapping wing power generation device according to claim 1, characterized in that, The pitch drive assembly also includes: Multiple pressure sensors are respectively installed on the first and second pressure chambers to collect pressure signals in the two pressure chambers; each pressure sensor is communicatively connected to the controller, which determines the target pressure difference based on the actual pitch angle, the target pitch angle, and the pressure signals from the two pressure chambers, and then controls the valve group to adjust the actual pressure difference between the first and second pressure chambers.

3. The pneumatic pitch drive system for an underwater semi-active flapping wing power generation device according to claim 2, characterized in that, The gas supply module also includes: The pressure-stabilizing chamber is connected to the gas source via a connecting pipe; The system includes an intake pipe and an exhaust pipe, both of which are flexible pipes. The intake pipe has two branches, which are connected from the pressure stabilizing chamber to the first pressure chamber and the second pressure chamber, respectively. The exhaust pipe has two branches, which are led out from the first pressure chamber and the second pressure chamber, respectively, and the end is an exhaust port.

4. The pneumatic pitch drive system for an underwater semi-active flapping wing power generation device according to claim 3, characterized in that, The valve assembly includes: a first pressure regulating valve, a second pressure regulating valve, a first vent valve, and a second vent valve; The first pressure regulating valve and the second pressure regulating valve are respectively installed on the two air inlet pipes, and are used to control the air supply to the first air pressure chamber and the second air pressure chamber respectively; The first exhaust valve and the second exhaust valve are respectively installed on the two exhaust pipes and are used to control the exhaust of the first air pressure chamber and the second air pressure chamber respectively.

5. The pneumatic pitch drive system for an underwater semi-active flapping wing power generation device according to claim 4, characterized in that, The controller is configured as follows: When the flapping wings need to pitch in the first direction, the first pressure regulating valve is controlled to increase the air supply pressure to increase the pressure of the first air chamber, and the second exhaust valve is controlled to open or the second pressure regulating valve is controlled to decrease the air supply pressure to reduce the pressure of the second air chamber, so that the pressure of the first air chamber is greater than the pressure of the second air chamber. When the flapping wings need to pitch in the second direction, the second pressure regulating valve is controlled to increase the air supply pressure to increase the pressure of the second air chamber, and the first exhaust valve is controlled to open or the first pressure regulating valve is controlled to decrease the air supply pressure to reduce the pressure of the first air chamber, so that the pressure of the second air chamber is greater than the pressure of the first air chamber.

6. The pneumatic pitch drive system for an underwater semi-active flapping wing power generation device according to claim 1, characterized in that, The mounting frame includes: a water platform, a slide rail, a reinforcing rib, and a base; the slide rail is vertically disposed between the water platform and the base; the reinforcing rib connects the water platform and the base. The motion module also includes: Two air pressure chamber clamps are respectively sleeved on the outside of the first air pressure chamber and the second air pressure chamber. The two air pressure chamber clamps are fixedly connected by a connecting rod to fix the first air pressure chamber and the second air pressure chamber. Two sliders are fixedly mounted on the two pneumatic chamber clamps respectively, and slide in cooperation with the slide rail to realize the floating and sinking movement of the motion module.

7. The pneumatic pitch drive system for an underwater semi-active flapping wing power generation device according to claim 3, characterized in that, The gas supply module also includes an air filter and a pressure reducing valve; the air filter and pressure reducing valve are disposed on the connecting pipe between the pressure regulating chamber and the gas source.

8. The pneumatic pitch drive system for an underwater semi-active flapping wing power generation device according to claim 1, characterized in that, The angle detection element is an absolute angle encoder, which is mounted on the connecting shaft between the gear and the flapping wing.

9. A pneumatic pitch drive method for an underwater semi-active flapping wing power generation device, implemented using the system described in any one of claims 1 to 8, characterized in that, Includes the following steps: Generate the target pitch angle signal for flapping wings; The actual pitch angle of the flapping wing is collected in real time by the angle detection element and fed back to the controller; The controller adjusts the air supply and exhaust states of the first and second air pressure chambers independently through the valve group according to the deviation between the target pitch angle and the actual pitch angle, so as to change the pressure difference between the two air pressure chambers. The piston-rack assembly is driven to reciprocate by the pressure difference, and the flapping wings are driven to pitch through the meshing of the rack and gear. By repeatedly collecting data from the angle detection element, adjusting the controller, and driving the piston-rack assembly, the actual pitch angle of the flapping wing continuously tracks the target pitch angle, forming a closed-loop control.

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