A pulsed liquid jet control system and method for offshore wind turbine attitude control

Abstract

The application provides a pulse liquid jet control system and method for floating wind turbine attitude control. The liquid in the liquid storage tank is driven by air pressure and transported to multiple nozzles arranged along the circumference of the platform through multiple independently controlled liquid pipes; the instantaneous flow, injection duration and pulse duty cycle of the liquid are independently adjusted for each nozzle to generate adjustable jet reaction force; the reaction force forms a control moment relative to the mass center of the platform to offset the attitude deviation caused by wind and waves. The attitude acquisition unit obtains the three-axis attitude angle and angular velocity of the platform in real time, the control unit calculates the target compensation moment using the PID algorithm, and maps the moment demand to the flow control instruction of each nozzle through the thrust distribution and flow conversion algorithm to form a closed-loop feedback. The system realizes active attitude correction of the floating wind turbine platform in the roll, pitch and yaw degrees of freedom through closed-loop feedback, and the control delay mainly depends on the control algorithm operation period and the valve response time.

Description

Technical Field

[0001] This invention relates to the field of attitude control technology for offshore wind turbines, specifically to a pulsed liquid jet control system and method for attitude control of floating wind turbines. Background Technology

[0002] Floating offshore wind turbines, with their towers and nacelles supported by floating foundations, represent a key technological approach for developing deep-sea wind energy resources. Compared to stationary offshore wind turbines, floating platforms exhibit significant roll, pitch, and yaw motion responses under the combined effects of wind, waves, and currents.

[0003] Existing attitude control methods for floating wind turbines mainly include the following categories: mooring systems passively limit the platform's range of motion by using the tension restoring torque of mooring cables; ballast systems change the platform's center of gravity and buoyancy by adjusting the water volume in the ballast tanks inside the floating body; and turbine body control indirectly affects the platform's attitude by changing the aerodynamic thrust of the impeller through pitch and generator torque regulation. Among these, ballast regulation relies on pumps and piping systems, and completing a single ballast water transfer typically takes tens of seconds to several minutes, making it difficult to effectively cope with sudden gusts and wave effects on a timescale of seconds; while pitch and torque control can achieve response times on the order of seconds, their system design goal is to optimize power generation, and when used for attitude control, power generation efficiency will inevitably be sacrificed; and adding large active mechanical actuators (such as gyro stabilizers and active ballast movement) will significantly increase the complexity of the floating body structure and the cost of modification.

[0004] In the field of marine engineering, liquid jet propulsion technology has been used for attitude control of underwater vehicles. Its basic principle is that when a nozzle ejects liquid at high speed, a reverse thrust is generated based on the conservation of momentum. However, in the field of floating wind turbine attitude control, a technical solution combining pulsed liquid jet propulsion with real-time closed-loop feedback of the platform's attitude has not yet emerged. Therefore, there is a need for an active attitude control system and method that is fast-responding, relatively simple in structure, and does not interfere with the wind turbine's power generation operation. Summary of the Invention

[0005] This invention provides a pulsed liquid jet control system for attitude control of a floating fan, comprising a pneumatic supply unit, a liquid storage tank, a liquid pipeline, at least three nozzles, a liquid flow controller corresponding to the number of nozzles, an attitude acquisition unit, and a control unit.

[0006] The air pressure supply unit is connected to the liquid storage tank to provide adjustable air pressure. The liquid storage tank is connected to the inlet of each liquid flow controller via liquid pipelines, and the outlet of each liquid flow controller is connected to the corresponding nozzle. The nozzles are arranged circumferentially along the floating blower platform, and the spray direction of each nozzle is set to generate an attitude correction torque relative to the platform's center of mass from the jet reaction force. The liquid flow controller is used to independently adjust the liquid flow rate, spray duration, and pulse duty cycle of the corresponding nozzle under the control of the control unit. The attitude acquisition unit is fixedly installed on the floating blower platform and electrically connected to the control unit to collect the platform's attitude angle and angular velocity in real time. The control unit is electrically connected to each liquid flow controller to calculate the target compensation torque based on the attitude information output by the attitude acquisition unit and to generate flow control commands for each nozzle through thrust distribution and flow conversion.

[0007] In some embodiments, the air pressure supply unit includes an air compressor, an air tank, a pressure regulating valve, and an air pressure sensor; the output port of the air compressor is connected to the inlet of the air tank, and the outlet of the air tank is connected to the liquid storage tank via the pressure regulating valve; the air pressure sensor is installed at the outlet pipeline of the pressure regulating valve to monitor the air pressure supplied to the liquid storage tank in real time and to provide feedback to the control unit.

[0008] In some embodiments, the liquid storage tank includes a liquid storage tank, an air inlet, a liquid outlet, and a filter component; the air inlet is connected to an air pressure supply unit, and the liquid outlet is connected to a liquid pipeline; the filter component is disposed at the liquid outlet or the inlet of the liquid pipeline to intercept particulate impurities in the liquid and prevent nozzle clogging.

[0009] In some embodiments, the liquid pipeline includes a main pipeline and multiple branch pipelines. One end of the main pipeline is connected to the outlet port of the storage tank, and the other end branches into multiple branch pipelines. Each branch pipeline is equipped with a check valve and a shut-off valve. The check valve is used to prevent liquid backflow, and the shut-off valve is used to cut off the liquid flow of the corresponding branch in case of maintenance or failure.

[0010] In some embodiments, the number of nozzles is three, and the three nozzles are evenly arranged at 120° azimuth intervals along the circumference of the floating wind turbine platform; each nozzle is a convergent conical nozzle, and its jet direction unit vector has a preset angle relative to the radial direction of the platform, so that the jet reaction force has both radial and tangential components, thereby generating a control torque covering the degrees of freedom of roll, pitch and yaw.

[0011] In some implementations, the liquid flow controller has a continuous flow regulation mode and a pulse operating mode; in the pulse operating mode, the liquid flow controller periodically opens and closes the valve under constant opening conditions according to the pulse duty cycle command output by the control unit, so that the average flow rate of the nozzle is the product of the target volume flow rate and the pulse duty cycle.

[0012] In some implementations, the control unit is used to execute the following control flow: The raw attitude data output by the attitude acquisition unit is subjected to low-pass filtering to obtain the real-time attitude angle vector and attitude angular velocity vector. Calculate the attitude deviation vector and the rate of change of deviation between the real-time attitude angle and the preset equilibrium attitude angle; When the magnitude of the attitude deviation vector exceeds the preset control start threshold or the magnitude of the angular velocity vector exceeds the preset angular velocity start threshold, the system enters the active jet control state; otherwise, it is in standby state and each liquid flow controller remains closed. Under active jet control, the target compensation torque vector is calculated according to the PID control law; Based on the installation position vector and the unit vector of the injection direction of each nozzle, the target compensation torque is distributed as the target jet thrust of each nozzle; Based on the physical relationship between jet thrust and liquid flow rate, the target jet thrust is converted into the target volumetric flow rate, and opening instructions and pulse duty cycle instructions for each liquid flow controller are generated.

[0013] In some implementations, the control unit performs constraint limiting on the target jet thrust of each nozzle during the thrust distribution process: if the calculated target thrust is less than zero, the target thrust of the nozzle is set to zero; if the calculated target thrust is greater than the maximum allowable thrust of the nozzle, the target thrust of the nozzle is set to the maximum allowable thrust; the torque difference generated after limiting is compensated by the remaining unsaturated nozzles through secondary distribution.

[0014] In some implementations, the target compensation torque vector Md(t) is calculated according to the following PID control law: ; In the formula, The target compensation torque vector; This is the attitude deviation vector; This is the platform attitude angle vector; Preset equilibrium attitude vector; , , These are respectively the roll angle, pitch angle, and yaw angle; This represents the rate of change of attitude deviation. , , These are the proportional, differential, and integral gain matrices, respectively.

[0015] The control unit distributes torque according to the nozzle installation position and spray direction, and satisfies the following relationship: ; In the formula, Number the nozzles; The jet control torque generated by the three nozzles together; Let be the installation position vector of the i-th nozzle relative to the platform's center of mass; Let be the unit vector of the injection direction of the i-th nozzle; Let be the jet thrust of the i-th nozzle; The target compensation torque. When When the allowable range is exceeded, the control unit shall follow Limit the amplitude.

[0016] The physical relationship between jet thrust and liquid flow rate is as follows: ; In the formula, The actual jet thrust of the i-th nozzle. Let CT be the target jet thrust of the i-th nozzle, and CT be the nozzle thrust coefficient. For the density of the liquid, Let i be the actual volumetric flow rate of the i-th nozzle. Let i be the target volumetric flow rate of the i-th nozzle. Let i be the outlet area of ​​the i-th nozzle. Let be the outlet diameter of the i-th nozzle. The control unit determines this based on... Generate the liquid flow controller's opening degree, injection duration, and pulse duty cycle.

[0017] The pulse duty cycle is determined according to the following formula: ; In the formula, Let be the pulse duty cycle of the i-th nozzle; Let i be the target volumetric flow rate of the i-th nozzle; Let be the maximum permissible volumetric flow rate of the i-th liquid flow controller.

[0018] In some implementations, the control unit also includes a safety protection module for setting all liquid flow controller output signals to zero and outputting an alarm signal when any of the following conditions are triggered: the pressure of the gas tank is lower than a preset safety lower limit, the liquid level of the liquid tank is lower than a preset lower limit, the deviation between the feedback flow and the command flow of any liquid flow controller continues to exceed the allowable range for a preset duration, the attitude acquisition unit signal is continuously lost for more than a preset number of sampling cycles, or the absolute value of any attitude angle of the platform exceeds a preset safety limit.

[0019] In some embodiments, the liquid is fresh water, seawater, or a circulating liquid containing corrosion inhibitors; the storage tank also includes a replenishment port and a return port, the replenishment port being used to replenish the liquid lost during spraying, and the return port being used to recover or recycle the liquid.

[0020] The present invention also provides a method for attitude control of a floating wind turbine using the above system, comprising the following steps: Step S1: The attitude acquisition unit collects the roll angle, pitch angle, yaw angle and corresponding angular velocity of the floating wind turbine platform in real time. Step S2: The control unit performs low-pass filtering on the original attitude data and calculates the attitude deviation vector and the rate of change of deviation between the real-time attitude and the preset equilibrium attitude. Step S3: When the magnitude of the attitude deviation vector or the magnitude of the angular velocity vector exceeds the preset control threshold, the control unit calculates the target compensation torque vector according to the PID control law. Step S4: The control unit distributes the target compensation torque into the target jet thrust of each nozzle according to the installation position vector and the unit vector of the jet direction of each nozzle, and performs constraint limiting of 0≤Fi≤Fimax and secondary distribution after limiting on the thrust distribution result. Step S5: The control unit calculates the target volumetric flow rate of each nozzle based on the thrust-flow relationship, and generates the target opening degree and pulse duty cycle of each liquid flow controller; Step S6: Each liquid flow controller adjusts the liquid flow of the corresponding nozzle according to the control command, so that the nozzle generates jet reaction force, forming a control torque acting on the platform to correct the platform attitude. Step S7: Repeat steps S1 to S6 to achieve closed-loop attitude control.

[0021] Compared with the prior art, the present invention has the following technical effects: The attitude correction response is fast. The response time of the liquid flow controller from receiving the command to completing the flow regulation is on the order of tens of milliseconds. The momentum transfer time of the jet from the nozzle outlet to the point of generating the reaction force is negligible. The overall system control delay is mainly determined by the control algorithm's computation cycle and the valve's mechanical response time, which is much smaller than the tens of seconds delay of the ballast regulation system. Therefore, the system can initiate active control intervention within one-tenth to one-hundredth of the wave motion timescale, applying restoring torque before the platform attitude deviates significantly, effectively suppressing the amplitude and duration of attitude oscillations.

[0022] The jet thrust can be continuously adjusted over a wide range to adapt to different sea conditions. Through a pulse duty cycle adjustment mechanism, while keeping the nozzle outlet area and supply pressure constant, the average thrust of a single nozzle can vary quasi-continuously between zero and the maximum continuous thrust, realizing the analog output of the actuator. When the platform attitude deviation is small, the system outputs small thrust with a low duty cycle for fine-tuning, avoiding overcorrection; when encountering sudden strong gusts or large waves that cause a sharp increase in attitude deviation, the system automatically increases the duty cycle to the upper limit to output the maximum thrust, achieving rapid attitude recovery.

[0023] Multi-nozzle cooperative control enables combined correction of three-degree-of-freedom attitude. Three nozzles are arranged at 120° intervals along the platform's circumference. The torque vector generated by the jet reaction force of each nozzle relative to the platform's center of mass has different directional components in space. The linear combination of these three torque vectors can cover the control torque space required for the three rotational degrees of freedom: roll, pitch, and yaw. By calculating the thrust contribution of each nozzle based on real-time attitude deviations using a thrust distribution algorithm, the system can simultaneously correct attitude deviations in multiple degrees of freedom.

[0024] The actuator has a simple structure, low modification cost, and is easy to deploy on existing platforms. The core components of the system are all industrial standard parts, which only need to be installed on the floating wind turbine platform and connected by pipelines and cables. There is no need to modify the structural load-bearing components of the floating body, the tower, the mooring system, or the wind turbine electrical control system. The installation workload, construction difficulty, and impact on the original structure of the platform are significantly lower than the solution of installing a large mechanical actuator.

[0025] The system has comprehensive safety protection functions. By monitoring the pressure of the gas storage tank, the liquid level of the liquid storage tank, the feedback status of the flow controller, the signal of the attitude acquisition unit, and the platform attitude angle in real time, it can automatically stop the jet spraying and output an alarm signal in abnormal operating conditions to prevent equipment damage or platform safety risks. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the pulsed liquid jet control system for attitude control of a floating fan according to the present invention; Figure 2 This is a comparison chart of the pitch angle response of the present invention with no control and PID control when the initial pitch is -10°.

[0027] Reference numerals in the attached diagram: 1. Air pressure supply unit; 2. Liquid storage tank; 3. Nozzle; 4. Attitude acquisition unit; 5. Control unit; 6. Liquid flow controller; 7. Multi-section liquid pipeline. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] Example 1: Attitude Control System of Floating Wind Turbine Model Test Platform This embodiment uses a semi-submersible floating wind turbine model test platform with a scale of 1:50 as the application object to describe the specific implementation of the present invention.

[0030] 1. Parameters of the floating wind turbine model platform The floating wind turbine model platform used in this embodiment adopts a semi-submersible floating foundation, with the main floating structure consisting of three columns and a central column. The upper part is supported by a tower supporting the wind turbine nacelle and rotor model. The total mass of the platform is approximately 80 kg, and the moment of inertia relative to the roll axis (x-axis) is I. roll Approximately 12 kg·m 2 The moment of inertia I relative to the pitch axis (y-axis) pitch Approximately 15 kg·m 2 Moment of inertia I relative to the yaw axis (z-axis) yaw Approximately 18 kg·m 2 The mooring system uses four catenary mooring cables, which are connected to the four corners of the platform. The equivalent mooring stiffness is approximately 50 N·m / ° in both the roll and pitch directions.

[0031] 2. Specific composition of air pressure supply unit 1 The air pressure supply unit 1 includes a small oil-free air compressor, an air tank, a precision pressure regulating valve, and an air pressure sensor.

[0032] The air compressor is a 750W oil-free reciprocating air compressor with a maximum discharge pressure of 0.8MPa and a discharge volume of approximately 60L / min. Automatic start-stop control is achieved through a power switch and a pressure switch—it automatically starts when the air tank pressure is below 0.5MPa and automatically stops when it is above 0.8MPa.

[0033] The gas storage tank has a volume of 24L and a designed working pressure of 0.8MPa. The tank body is made of carbon steel with rust-proof treatment on both the inner and outer surfaces. A safety valve (with an opening pressure set at 0.9MPa to prevent overpressure hazards) and a pressure gauge (for visually reading the pressure value on-site) are installed on the top of the tank. A drain valve is located at the bottom of the tank for periodically draining condensate. The gas storage tank outlet is connected to the inlet of a precision pressure regulating valve via a high-pressure hose.

[0034] The precision pressure regulating valve is a diaphragm-type precision pressure reducing valve, with an outlet pressure adjustment range of 0.05~0.7MPa and an adjustment accuracy of ±0.01MPa. In this embodiment, the outlet pressure of the pressure regulating valve is set to 0.3MPa—this pressure value is determined based on a comprehensive calculation of the nozzle 3 outlet diameter, maximum design thrust, and pipeline friction loss. The outlet of the pressure regulating valve is connected to the air inlet of the liquid storage tank 2 via a high-pressure hose.

[0035] The pressure sensor is a diffused silicon pressure transmitter with a range of 0~1.0MPa, outputting a 4~20mA analog current signal with an accuracy class of 0.5%FS. The pressure sensor is installed on the tee connector of the pressure regulating valve outlet pipeline, and its signal line is connected to the analog input channel of control unit 5 to monitor the actual pressure value supplied to storage tank 2 in real time. When the pressure sensor detects an output pressure below 0.15MPa (below the minimum pressure required for normal operation, which will result in severely insufficient jet thrust), control unit 5 determines it as an abnormal pressure and triggers a safety protection action.

[0036] 3. Specific composition of storage tank 2 The liquid storage tank 2 includes a liquid storage tank 2, an air inlet, a liquid outlet, a liquid replenishment inlet, a liquid drain inlet, and a filter component.

[0037] Storage tank 2 is a cylindrical stainless steel pressure vessel with a total volume of 30L and a designed working pressure of 0.6MPa. Two ports are located at the top of the tank: an air inlet (connected to the output pipeline of air supply unit 1) and a liquid replenishment port (used to replenish working liquid after consumption; normally sealed with a blind flange). An outlet port and a drain port are located at the bottom of the tank. The outlet port is located on the bottom side wall of the tank, with the port pipeline extending downwards from inside the tank to approximately 2cm from the bottom, ensuring that liquid can be drawn in even at low liquid levels without drawing in sediment from the bottom. The drain port is located at the lowest point of the tank and is used to empty storage tank 2 after the test or to periodically remove impurities from the bottom of the tank.

[0038] The filter element is a Y-type pipeline filter, installed between the liquid outlet of the storage tank 2 and the inlet of the main liquid pipeline. The filter screen is made of stainless steel woven mesh with a mesh size of 150μm. This mesh size can effectively intercept particulate impurities that may clog the nozzle 3 (the outlet diameter of the nozzle 3 is 4mm; 150μm particles can pass through the nozzle 3, but frequent impacts may cause wear; interception extends the life of the nozzle 3) without excessively increasing the flow resistance of the pipeline.

[0039] The working liquid in storage tank 2 is tap water. For long-term operation, a small amount of environmentally friendly corrosion inhibitor (such as sodium benzoate, concentration 0.1%~0.2%) can be added to the water to prevent the growth of microorganisms on the inner walls of storage tank 2 and pipelines.

[0040] 4. Specific composition of liquid pipelines and branches The liquid pipeline is specifically constructed as follows: the main pipeline uses a 20mm inner diameter PU (polyurethane) high-pressure hose with a maximum working pressure of 1.0MPa and a length of approximately 2m. One end connects to the outlet of the filter component via a quick connector, and the other end branches into three branch pipelines via a four-way connector. Each of the three branch pipelines uses a 10mm inner diameter PU high-pressure hose with a maximum working pressure of 1.0MPa and a length of approximately 1.5m.

[0041] The following fittings are installed sequentially on each branch pipe: First, a manual shut-off valve (stainless steel ball valve, nominal diameter DN10). This shut-off valve remains open during normal operation and can be manually closed when maintenance is required or when a fault occurs in this line, cutting off the liquid flow in this line without affecting the normal operation of other branches. Then, a check valve (spring return type, opening pressure approximately 0.02MPa, forward flow direction from the main pipe to the liquid flow controller 6). This check valve is used to prevent the liquid in the branch pipe from flowing back into the main pipe due to gravity or pressure fluctuations during the intermittent spraying of nozzle 3 or when the system is shut down, thereby avoiding interference with the flow control accuracy of other branches.

[0042] The outlets of the three branch pipes are connected to the inlets of the three liquid flow controllers 6 via quick couplings.

[0043] 5. Specific selection and setting of liquid flow controller 6 All three liquid flow controllers are ACU-10L electronic liquid flow controllers. Each controller has a rated maximum flow rate of 10 L / min, a flow rate adjustment range of 0.2~10 L / min, and a flow control accuracy of ±2%FS. The control signal interface supports 0~10V analog voltage signals (input impedance greater than 10kΩ), where 0V corresponds to the valve being fully closed and 10V corresponds to the valve being fully open (i.e., maximum flow rate of 10 L / min). There is a linear relationship between the control voltage and the target flow rate.

[0044] The ACU-10L integrates an electromagnetic proportional valve and a turbine flow sensor. The electromagnetic proportional valve's spool response time (the time from receiving a change in the control signal to the spool displacement reaching 90%) is less than 30ms, meeting the 20Hz control cycle requirement of this embodiment. The turbine flow sensor detects the actual volumetric flow rate passing through the controller in real time and outputs a 4~20mA analog current feedback signal (4mA corresponds to 0L / min, 20mA corresponds to 10L / min). This feedback signal is connected to the analog input channel of the control unit 5 for flow closed-loop verification and fault detection.

[0045] The controller supports pulse operation mode: when the control unit 5 alternately outputs high-level and low-level control signals at a certain frequency, the electromagnetic proportional valve inside the controller can follow the signal to periodically open and close within the response time limit. By adjusting the proportion of the high level to the entire pulse cycle (i.e., the duty cycle), the average flow rate of the nozzle 3 within the pulse cycle can be approximately equal to the product of the target volumetric flow rate and the duty cycle, provided that the valve opening and closing response is fast enough.

[0046] Three liquid flow controllers 6 independently control three nozzles 3, and the controllers do not interfere with each other.

[0047] 6. Specific configuration of nozzle 3 The three nozzles 3 are arranged circumferentially along the edge of the model platform deck, with azimuth angles of 0°, 120° and 240° respectively (with the platform bow as the reference direction of 0°, and counterclockwise as positive).

[0048] The structure of each nozzle 3 is as follows: the nozzle body is a converging cone nozzle 3 made of brass, with an inlet inner diameter of 10mm (matching the inner diameter of the branch pipe), an outlet inner diameter di=4mm, and a convergence half-angle of 15°. The outlet area Ai of nozzle 3 is Ai=π×(4 / 2). 2 =12.57mm 2 The nozzle 3 outlet is machined with a smooth, converging surface to reduce jet contraction and turbulence losses. After calibration, the thrust coefficient CT of the nozzle 3 used in this embodiment is approximately 0.95 (this value remains essentially constant within the water supply pressure range of 0.2~0.5MPa).

[0049] Nozzle 3 is fixed to the lower edge of the platform deck using stainless steel brackets and bolts. The installation positions of each nozzle 3 (with the platform's center of gravity as the origin, x-axis pointing bow, y-axis pointing starboard, and z-axis vertically upward) are as follows: The first nozzle 3 (0° azimuth, located at the bow of the platform): installation position vector r1 = (1.20, 0, –0.15) m; The second nozzle 3 (120° azimuth, located to the right rear of the platform): installation position vector r2 = (–0.60, 1.04, –0.15) m; The third nozzle 3 (240° azimuth, located to the left rear of the platform): installation position vector r3 = (–0.60, –1.04, –0.15) m; The unit vectors n1, n2, and n3 of the jet direction for each nozzle 3 are set as follows: the projection of the axis of each nozzle 3 in the horizontal plane is deflected outward by 30° relative to the platform's radial direction (from the center of mass to the nozzle 3's installation position)—that is, the jet direction of the first nozzle 3 is deflected 30° forward and to starboard in the horizontal plane from the bow, the jet direction of the second nozzle 3 is deflected 30° in the horizontal plane from its radial direction, and the jet direction of the third nozzle 3 is deflected 30° in the horizontal plane from its radial direction. The outlet axis of the nozzle 3 is horizontal in the vertical plane (i.e., no elevation or depression angle). This jet direction configuration causes the jet reaction force of each nozzle 3 to simultaneously generate a radial moment component (for roll and pitch control) and a tangential moment component (for yaw control) relative to the platform's center of mass, so that the combination of the three nozzles 3 can generate control moments covering the three degrees of freedom of roll, pitch, and yaw.

[0050] In this embodiment, the maximum jet thrust Fimax of a single nozzle 3 under a water supply pressure of 0.3MPa and in the fully open state is measured to be approximately 12N, corresponding to a maximum volumetric flow rate of approximately 10L / min.

[0051] 7. Specific configuration of attitude acquisition unit 4 Attitude acquisition unit 4 uses an MPU6050 six-axis inertial measurement module. This module integrates a three-axis MEMS gyroscope (angular velocity range ±2000° / s, resolution 16.4 LSB / (° / s)), a three-axis MEMS accelerometer (range ±16g, resolution 2048 LSB / g), and a digital motion processor (DMP), which can output fused attitude angle data.

[0052] The MPU6050 module connects to I 2 The module communicates with the control unit via the C-bus, with a data refresh rate configured at 100Hz. The module is externally encapsulated in a waterproof aluminum alloy box, which is secured to the top platform of the model wind turbine nacelle using four M4 bolts. During installation, ensure that the module's x-axis (module coordinate definition) is aligned with the platform's bow direction, and that the module's mounting plane is parallel to the platform's deck surface. The waterproof box's cable outlet is sealed with a waterproof cable connector. 2 The C-type communication cable uses shielded twisted-pair cable, and the shielding layer is grounded at a single point on the control unit end.

[0053] Each time the system starts, it executes a zero-point self-calibration procedure: under still water and no wind conditions (the platform is in a natural equilibrium state), it continuously collects 100 samples of attitude angle data (sampling interval 10ms, total duration 1 second), calculates the arithmetic mean of the attitude angles of each axis as the initial zero bias value and writes it into the control program. Subsequent real-time attitude angles must be deducted from this zero bias value.

[0054] 8. Specific composition of control unit 5 Control unit 5 is based on the STM32F407VGT6 microcontroller. This microcontroller is based on the ARM Cortex-M4 core, with a main frequency of 168MHz. It integrates a single-precision floating-point unit (FPU) and a digital signal processing (DSP) instruction set, which can efficiently perform floating-point operations required for control algorithms such as PID calculations, matrix operations, and square root calculations.

[0055] The hardware peripherals of control unit 5 are configured as follows: Analog output: The microcontroller uses three 12-bit DACs (digital-to-analog converters) inside, with an output range of 0~3.3V. The output is conditioned to 0~10V by an external operational amplifier (LM358) non-inverting amplifier circuit, and then output to three liquid flow controllers as flow control signals.

[0056] Analog Input: The microcontroller utilizes three internal 12-bit ADCs (Analog-to-Digital Converters) to receive 4-20mA flow signals from three liquid flow controllers. Each 4-20mA current flows through a sampling resistor with an accuracy of 250Ω±0.1%, is converted to a 1-5V voltage, and then input to the ADC channel. An additional ADC channel receives a 4-20mA signal from a pressure sensor.

[0057] Digital Communications: I 2 The C interface is used to communicate with the MPU6050 attitude acquisition unit; the UART serial port is used to communicate with the host computer to realize online parameter adjustment and data recording.

[0058] Power Supply: Control Unit 5 is powered by 24V DC (converted from 220V AC via a switching power supply). The board outputs 5V and 3.3V via DC-DC converters to power the various chips. The analog output circuit uses an independent 5V reference voltage source (REF02) to improve DAC output accuracy.

[0059] Control unit 5 is installed in a waterproof electrical control box, which is fixed above the model platform deck. All signal cables and power cables enter and exit through waterproof cable connectors at the bottom of the box.

[0060] II. Control Parameter Setting Based on the hydrodynamic characteristics of the model platform and multiple experimental adjustments, the following control parameters are adopted in this embodiment: Control start-up threshold setting: The magnitude of the attitude angle deviation vector ||e(t)|| = √(φ) 2 +θ 2 +ψ 2 The initiation threshold is 3°, and the magnitude of the attitude angular velocity vector is... The startup threshold is 1.5° / s. When the magnitudes of both vectors are below their respective thresholds, the system is in standby mode, all liquid flow controllers remain fully off, no liquid is consumed, and no jet thrust is generated.

[0061] PID control parameter tuning: Due to the different hydrodynamic restoring torque and damping characteristics in the roll and pitch directions, independent parameter settings for each channel are adopted.

[0062] Roll channel (corresponding to the target torque component in the Roll direction): Kp roll =2.5 N·m / °, Kd roll =1.2 N·m·s / °, Ki roll =0.1 N·m / (°·s) Pitch channel (corresponding to the target moment component in the Pitch direction): Kp pitch =2.0 N·m / °, Kd pitch =1.0 N·m·s / °, Ki pitch=0.1 N·m / (°·s) Yaw channel (corresponding to the target moment component in the yaw direction): Kp yaw =1.5 N·m / °, Kd yaw =0.8 N·m·s / °, Ki yaw =0.05 N·m / (°·s) Control period T control The control cycle is set to 50ms (corresponding to a control frequency of 20Hz). Under this control cycle, the MPU6050 can provide 5 attitude data samples (100Hz refresh rate) in each control cycle. The average of the 5 samples is taken as the attitude input for this cycle to reduce the influence of random noise.

[0063] Low-pass filter settings: A first-order digital Butterworth low-pass filter is used, with a cutoff frequency set to 8Hz. This cutoff frequency is higher than the dominant frequency of the platform's attitude motion (the dominant frequency of the model platform's response to waves is usually 0.5~2Hz), which can preserve complete attitude motion information while effectively filtering out high-frequency structural vibrations (above 10Hz) and sensor background noise.

[0064] Pulse injection parameter settings: The pulse frequency is set to 5Hz (pulse period T_pulse=200ms). At this frequency, the response time of the liquid flow controller (<30ms) is much shorter than the pulse period, and the valve can fully respond to the opening and closing commands of each pulse. The duty cycle Di is adjustable from 0 to 100%, adjusted in 5% steps (corresponding to 20 adjustable levels, meeting the control accuracy requirements).

[0065] III. System Workflow The following describes in detail the complete process of the system from startup to entering the normal closed-loop control cycle.

[0066] (I) System Initialization and Startup Step 1: Check the pipeline connections. Confirm that all quick-connect fittings are locked, all manual shut-off valves are in the normally open position, and the liquid level in storage tank 2 is within the normal range (the liquid level is at least 5cm above the outlet and at least 5cm below the inlet to prevent liquid from entering the pneumatic pipeline).

[0067] Step 2: Start the air compressor. Close the air compressor power switch, and the air compressor will begin filling the air tank. Once the air tank pressure gauge indicates a pressure above 0.6 MPa, adjust the precision pressure regulating valve to stabilize the outlet pressure at 0.3 MPa. At this point, the pressure signal fed back to control unit 5 by the pressure sensor should be approximately 0.3 MPa (corresponding to 12 mA current).

[0068] Step 3: The control unit 5 is powered on and completes a self-test. First, the control unit 5 reads the pressure sensor value to confirm it is within the normal range; then, it sequentially sends brief full-open and full-close commands to the three liquid flow controllers 6, reads the flow feedback signals from each controller, and confirms that the communication and operation of the three flow controllers are normal. After the self-test passes, the control unit 5 sends a "system ready" status code to the host computer via the UART serial port.

[0069] Step 4: Zero-point calibration of attitude acquisition unit 4. Under still water and windless conditions (model platform in free-floating equilibrium), the control unit continuously reads the attitude angle data output by MPU6050 via the I²C bus, acquiring 100 samples (taking 1 second), and calculates the arithmetic mean φ of roll, pitch, and yaw angles. offset θ offse t、ψ offset The zero-bias compensation value is written into the control program. After calibration, the control unit 5 sends the calibration result data to the host computer.

[0070] Step 5: Set control parameters and balance attitude angle. Send PID control parameters (Kp, Kd, ​​Ki channel values), control start threshold, pulse frequency, and target balance attitude angle to control unit 5 via the host computer's serial port. In this embodiment, the equilibrium attitude angle is set to... This means that the platform is expected to remain horizontal and its orientation unchanged.

[0071] Step 6: The system enters standby monitoring mode. Control unit 5 begins to read attitude data and calculate attitude deviation in a 50ms cycle, but liquid flow controller 6 remains fully off (0V), and nozzle 3 does not spray. At this time, the system is in a "sensing-judgment" state, waiting for the trigger condition.

[0072] (ii) Real-time closed-loop control cycle The following describes in detail the internal calculation and decision-making process of control unit 5, taking a complete control cycle (50ms) as an example.

[0073] Let the current time be t and the previous control period be t-50ms.

[0074] t=0ms (control cycle begins): Control unit 55 via I 2 The C bus sends a data request command to the MPU6050 to read the latest attitude data register values, including the raw values ​​of the three-axis angular velocities and the raw values ​​of the three-axis accelerations. Since the DMP of the MPU6050 is enabled, the attitude quaternion or Euler angle data calculated by DMP can also be read directly.

[0075] t=2ms: Attitude calculation and zero-bias correction. The zero-bias compensation value obtained in step 4 is subtracted from the read raw attitude angle data to obtain the real-time attitude angle of the current sampling point. The arithmetic mean of the attitude angles of the most recent 5 sampling points (current period + 4 points from the historical buffer, corresponding to 5 100Hz samples within a 50ms time window) is taken as the real-time attitude angle vector for this period. Similarly, calculate the attitude angular velocity vector. .

[0076] Assuming the measurement at the current time is: , The data indicates that the platform is tilted 8.5° to port (negative x-axis rotation direction), 4.2° to the stern (positive y-axis rotation direction), and yawed 1.8° to the right; and the platform is continuing to tilt to port at a rate of 0.8° / s and to the rear at a rate of 0.3° / s.

[0077] t=4ms: Low-pass filtering. The vector is subjected to a first-order Butterworth low-pass filter (cutoff frequency 8Hz) to eliminate the influence of high-frequency vibrations on the differential term calculation. The filtered angular velocity vector is: .

[0078] t=6ms: Calculate attitude deviation. Calculate the rate of change of attitude deviation. (use (value).

[0079] t=8ms: Control the start-up decision. Calculate ||e(t)|| = √(–8.5) 2 +4.2 2 +1.8 2 )≈√(72.25+17.64+3.24)=√93.13≈9.7°>3° threshold, the system determines to enter active jet control state. If ||e(t)||≤3° and If so, the output of the three-way liquid flow controller 6 will be set to zero, skipping subsequent control calculations and directly entering the next cycle.

[0080] t=10ms: PID control torque calculation. Calculate the target compensation torque components for each of the three channels.

[0081] Roll: Proportional term: ; Differential term: ; Points Item: Update accumulated points Where Δt = 0.05s, and assuming the historical cumulative integral value is –15.6°·s (the cumulative leftward tilt of the platform during previous periods), then the integral term = ; ; Pitch: Proportional term: ; Differential term: ; Integral term: Let Integral term = ; ; Yaw: Proportional term: ; Differential term: ; Integral term: Let Integral term = ; ; Obtain the target compensation torque vector .

[0082] t=15ms: Thrust distribution calculation. Based on the moment distribution equation. Solve for the target thrust of each nozzle 3.

[0083] Will coordinates and Substituting the directional values ​​into the system of equations, we calculate the unconstrained least squares solution and obtain the preliminary thrust distribution for each nozzle 3: .

[0084] Constraint check: F imax =12N (maximum thrust of a single nozzle 3 in this embodiment). Check each thrust value: F1unc=8.2N, within the range of 0~12N, no amplitude limiting is required; F2unc=5.1N, within the range of 0~12N, no amplitude limiting is required; F3unc=3.8N, within the range of 0~12N, no amplitude limiting is required.

[0085] All three thrusts are within the allowable range, so no constraint limiting or secondary distribution is required. The final target thrusts for each nozzle are: F1 = 8.2 N, F2 = 5.1 N, and F3 = 3.8 N.

[0086] t=18ms: Flow conversion calculation. Based on the thrust-flow relationship: ; Calculate the target volumetric flow rate required for each nozzle 3. Use the liquid density... Nozzle 3 outlet area The thrust coefficient CT = 0.95.

[0087] First nozzle 3: Recalculate: , The ratio is , .

[0088] Second nozzle 3: The ratio is , .

[0089] The third nozzle 3: The ratio is , .

[0090] t=20ms: Duty cycle and command generation calculation. Qimax = 10L / min (ACU - 10L rated maximum flow rate).

[0091] ; ; ; At a pulse frequency of 5Hz (period 200ms), the opening and closing times of each nozzle 3 within each pulse cycle are as follows: First nozzle 3: Opening time 200 × 0.33 = 66ms, Closing time 134ms Second nozzle 3: Opening time 200 × 0.26 = 52ms, Closing time 148ms The third nozzle (3): Opening time: 200 × 0.22 = 44 ms; Closing time: 156 ms Control unit 5 converts the duty cycle into a corresponding control voltage: a 0~100% duty cycle linearly corresponds to a 0~10V output. Therefore: The control voltage for the first nozzle 3 is 0.33 × 10V = 3.30V. The control voltage for the second nozzle 3 is 0.26 × 10V = 2.60V. The control voltage for the third nozzle is 0.22 × 10V = 2.20V. t=25ms: Control command output. Control unit 5 simultaneously updates the output voltage to three liquid flow controllers 6 via three DACs. Simultaneously, it reads the actual flow feedback signal from the flow controllers via three ADC channels and compares it with the commanded flow rate for verification. Data such as the timestamp, attitude angle, target torque, thrust of each nozzle 3, and flow rate for this cycle are packaged and sent to the host computer for storage via UART serial port.

[0092] t=30~80ms: Actuator response phase. After receiving the updated control voltage, the three liquid flow controllers 6 complete the valve core displacement adjustment within 30ms using their internal electromagnetic proportional valves. In pulse operation mode, the internal drive circuit of the controller controls the periodic opening and closing of the valve according to a frequency of 5Hz and the corresponding duty cycle. Under the pressure (0.3MPa) of the storage tank 2, the liquid is ejected through the main pipeline → branch pipeline → flow controller → nozzle 3.

[0093] The reaction force of the jet ejected from nozzle 3 acts on the platform. The resultant torque of the three paths is approximately... The direction of this torque is opposite to the direction of attitude deviation—the direction of roll. The torque resists the platform's tendency to tilt to the left, in the pitch direction. The torque resists the tendency of the platform to tilt backward.

[0094] t=50ms (start of the next control cycle): Control unit 5 repeats the above process. In the new cycle, since the jet control torque has been applied to the platform for 50ms, the platform attitude angle and angular velocity will change accordingly (the expected roll and pitch angles will decrease). The integral term of the PID algorithm is updated cumulatively based on the new attitude deviation, and the derivative term is recalculated based on the new angular velocity. The control command is dynamically adjusted—as the attitude deviation gradually decreases, the duty cycle and thrust also decrease accordingly to avoid overcorrection and reverse overshoot.

[0095] (III) Attitude recovery and steady-state maintenance As the closed-loop control cycle continues to run, the platform attitude deviation gradually decreases. When ||e(t)|| decreases to within the 3° threshold and When the flow rate decreases to within the 1.5° / s threshold, the control unit 5 determines that the platform has returned to the stable range, sets the output of all liquid flow controllers 6 to zero, and the system exits the active jet control state and returns to the standby monitoring state.

[0096] If subsequent wind and waves cause the platform's attitude to exceed the threshold again, the system can seamlessly re-enter active control mode. This "on-demand start-up, adaptive adjustment" working mode ensures attitude control effectiveness while minimizing fluid consumption and system energy consumption.

[0097] IV. Security Protection Mechanism In this embodiment, the following safety protection logic is integrated into the control unit 5, and each protection condition is cyclically detected at control cycle (50ms) intervals.

[0098] Protection Condition 1 – Low Pressure Protection: When the pressure sensor reports a pressure below 0.15 MPa (possibly due to air compressor failure, air tank leakage, or pressure regulating valve malfunction), control unit 5 determines that the jet thrust will be severely insufficient, making effective attitude control impossible. At this time, control unit 5 immediately sets the output signal of the three-way liquid flow controller 6 to zero (0V), closes all nozzles 3, and sends alarm code 0x01 (low pressure) to the host computer via UART.

[0099] Protection Condition 2 – Low Liquid Level Protection: A float-type liquid level switch is installed inside the storage tank 2. When the liquid level is 3cm below the outlet port, the switch contacts open. Upon detecting this signal, the control unit 5 determines that the liquid in the storage tank 2 is insufficient to maintain normal spraying—continued spraying may cause air to enter the liquid pipeline, leading to airlock in the nozzle 3 and unstable jet flow. At this time, the control unit 5 closes all nozzles 3 and sends alarm code 0x02 (low liquid level) to the host computer, prompting the operator to replenish the liquid.

[0100] Protection Condition 3 – Flow Feedback Abnormal Protection: In active control mode, the control unit 5 continuously compares the commanded flow rate Qi of each liquid flow controller 6 with the feedback flow rate Qi. fb If the deviation of a certain path is |Qi–Qi fb If the flow rate continuously exceeds 30% of the maximum flow rate of a given channel (i.e., 3 L / min) for more than 1 second (20 control cycles), the channel is considered faulty—possible causes include valve jamming, pipeline blockage, or flow sensor malfunction. Control unit 5 resets the output of the liquid flow controller 6 for that channel to zero, stops the injection in that channel, and sends alarm code 0x03 (abnormal flow) and the faulty channel number to the host computer. Other normal channels continue to operate, maintaining partial control capability.

[0101] Protection Condition 4 – Attitude Signal Loss Protection: Control Unit 5 attempts to read MPU6050 data via the I²C bus in each control cycle. If valid attitude data (I²C signal loss) is not successfully read for 10 consecutive control cycles (500ms), the system will terminate the protection. 2 If communication times out or data verification fails, the attitude acquisition unit 4 is determined to have experienced a communication interruption or sensor malfunction—at this point, the system loses its attitude sensing capability and cannot perform closed-loop control. The control unit 5 shuts down all nozzles 3 and sends alarm code 0x04 (attitude signal loss) to the host computer.

[0102] Protection Condition 5 – Attitude Angle Over-Limit Protection: If the absolute value of any attitude angle (roll, pitch, or yaw) exceeds 45° – this is the preset platform safety limit; exceeding this angle poses a risk of platform capsizing, and jet control alone is insufficient to restore a safe attitude – control unit 5 shuts down all nozzles 3 and sends alarm code 0x05 (Attitude Over-Limit) to the host computer. At this point, test personnel must assess the platform's safety status and take other intervention measures.

[0103] V. Experimental Verification and Results Data To verify the actual effect of the pulsed liquid jet control system described in this embodiment, a floating wind turbine model attitude response test platform was built in a wave pool.

[0104] Experimental conditions: The pool dimensions were 50m × 30m × 1.5m (length × width × depth). A wave generator produced regular waves with a wave height of 0.1m and a wave period of 1.5s. An axial flow fan was simultaneously installed upstream of the model to simulate wind load, with a wind speed of approximately 3m / s (corresponding to the model dimensions). The initial pitch angle of the platform was... The initial offset was set to -20° by artificially applying it (to simulate the severe forward tilting of the wind turbine caused by a sudden forward gust of wind).

[0105] Uncontrolled operation: Power to the three liquid flow controllers 6 is turned off (or the output of control unit 5 is kept at 0V), and the platform relies solely on the passive restoring torque provided by the mooring system for response. Pitch angle time history data is recorded over 25 seconds (MPU6050 sampling rate 100Hz). The test results show that the platform pitch angle oscillates from an initial -20°. Due to the limited restoring torque and insufficient damping provided by the mooring system, the pitch angle oscillates continuously between -20° and approximately +5°, with the oscillation amplitude decaying slowly. At the end of the 25-second sampling period, the pitch angle is still fluctuating within ±2°, failing to reach stability. The root mean square value of pitch (RMS) over 25 seconds is calculated to be 6.204°. The time required for the pitch angle to remain stable within ±1.5° is taken as the settling time, Ts≈22.96s.

[0106] PID control mode (Kp=2.0, Ki=0.0, Kd=0.0): The jet control system was started, and other test conditions remained the same as in the no-control mode. Test results showed that control unit 5 detected a pitch deviation of -20° in the first control cycle (far exceeding the 3° start-up threshold) and immediately entered active jet control mode; nozzle 3, located at the front of the platform, sprayed with a high duty cycle (initial D≈1.0), generating a restoring torque that lifted the bow; the pitch angle recovered rapidly from -20° to within -10° in approximately 5 seconds; subsequently, as the attitude deviation decreased, control unit 5 automatically reduced the duty cycle for fine adjustment; after approximately 17.75 seconds, the pitch angle stabilized within ±1.5°. The Pitch RMS was statistically calculated to be 5.388°, and the stabilization time Ts≈17.75s. The platform pitch time-history response was recorded under both the no-control and PID control modes, and the pitch response curves are shown below. Figure 2 As shown. Where P control is a PID control law in K... i =K d A special case when =0.

[0107] Quantitative analysis of control effect improvement: RMS improvement rate η RMS =(RMS0–RMS c ) / RMS0×100%=(6.204-5.388) / 6.204×100%=13.16%; Settlement time reduction rate η Ts =(Ts0-Ts c ) / Ts0×100%=(22.96-17.75) / 22.96×100%=22.68%.

[0108] The above experimental data show that the pulsed liquid jet control system described in this invention can effectively reduce the pitch oscillation amplitude of a floating wind turbine platform under wind-wave coupling (RMS reduction of 13.16%) and significantly accelerate the attitude recovery speed (stabilization time shortened by 22.68%). These effects are achieved using only proportional control (Kp=2.0, Ki=0.0, Kd=0.0). Further optimization of the derivative and integral control parameters is expected to further improve the control performance.

[0109] It should be understood that the above embodiments are merely exemplary. Those skilled in the art can make various non-substantial improvements and substitutions based on the technical concept of this invention, and all such improvements and substitutions should be considered to fall within the protection scope of this application.

Claims

1. A pulsed liquid jet control system for attitude control of a floating fan, characterized in that, It includes a pneumatic supply unit (1), a liquid storage tank (2), a liquid pipeline, at least three nozzles (3), a liquid flow controller (6) corresponding to the number of nozzles (3), an attitude acquisition unit (4), and a control unit (5); The air pressure supply unit (1) is connected to the liquid storage tank (2) and is used to provide adjustable air pressure to the liquid storage tank (2); The liquid storage tank (2) is connected to the inlet of each of the liquid flow controllers (6) via the liquid pipeline, and the outlet of each of the liquid flow controllers (6) is connected to the corresponding nozzle (3); The nozzles (3) are arranged circumferentially along the floating fan platform, and the spray direction of each nozzle (3) is set to enable the jet reaction force to generate an attitude correction torque relative to the center of mass of the platform. The liquid flow controller (6) is used to independently adjust the liquid flow rate, injection duration and pulse duty cycle of the corresponding nozzle (3) under the control of the control unit (5); The attitude acquisition unit (4) is fixedly installed on the floating wind turbine platform and electrically connected to the control unit (5) for real-time acquisition of the platform's attitude angle and angular velocity; The control unit (5) is electrically connected to each of the liquid flow controllers (6) and is used to calculate the target compensation torque based on the attitude information output by the attitude acquisition unit (4) and generate flow control commands for each nozzle (3) through thrust distribution and flow conversion.

2. The pulsed liquid jet control system according to claim 1, characterized in that, The air pressure supply unit (1) includes an air compressor, an air tank, a pressure regulating valve and an air pressure sensor; the output port of the air compressor is connected to the inlet of the air tank, and the outlet of the air tank is connected to the liquid storage tank (2) via the pressure regulating valve; the air pressure sensor is installed at the outlet pipeline of the pressure regulating valve and is used to monitor the air pressure supplied to the liquid storage tank (2) in real time and feed it back to the control unit (5).

3. The pulsed liquid jet control system according to claim 1, characterized in that, The liquid storage tank (2) includes a liquid storage tank (2), an air inlet, a liquid outlet, and a filter component; the air inlet is connected to the air pressure supply unit (1), and the liquid outlet is connected to the liquid pipeline; the filter component is located at the liquid outlet or the inlet of the liquid pipeline and is used to intercept particulate impurities in the liquid.

4. The pulsed liquid jet control system according to claim 1, characterized in that, The liquid pipeline includes a main pipeline and multiple branch pipelines. One end of the main pipeline is connected to the outlet of the liquid storage tank (2), and the other end is divided into multiple branch pipelines. Each branch pipeline is equipped with a check valve and a shut-off valve. The check valve is used to prevent liquid backflow, and the shut-off valve is used to cut off the liquid flow of the corresponding branch during maintenance or failure. The outlets of the multiple branch pipelines are respectively connected to the inlet of each liquid flow controller (6).

5. The pulsed liquid jet control system according to claim 1, characterized in that, The number of nozzles (3) is three, and the three nozzles (3) are evenly arranged at 120° azimuth intervals along the circumference of the floating wind turbine platform; each nozzle (3) adopts a convergent cone nozzle, and its jet direction unit vector has a preset angle relative to the radial direction of the platform, the preset angle being 20°~40°, so that the jet reaction force has both radial and tangential components, so as to generate a control torque covering the roll, pitch and yaw degrees of freedom.

6. The pulsed liquid jet control system according to claim 1, characterized in that, The liquid flow controller (6) has a continuous flow regulation mode and a pulse working mode. In the pulse working mode, the liquid flow controller (6) periodically opens and closes the valve under constant opening conditions according to the pulse duty cycle command output by the control unit (5), so that the average flow of the nozzle (3) is the product of the target volume flow rate and the pulse duty cycle.

7. A method for attitude control of a floating fan using the pulsed liquid jet control system according to any one of claims 1-6, characterized in that, Includes the following steps: The raw attitude data output by the attitude acquisition unit (4) is subjected to low-pass filtering to obtain the real-time attitude angle vector and attitude angular velocity vector; Calculate the attitude deviation vector and the rate of change of deviation between the real-time attitude angle and the preset equilibrium attitude angle; When the magnitude of the attitude deviation vector exceeds the preset control start threshold or the magnitude of the angular velocity vector exceeds the preset angular velocity start threshold, the system enters the active jet control state; otherwise, it is in standby state and each liquid flow controller (6) remains closed. Under active jet control, the target compensation torque vector is calculated according to the PID control law; Based on the installation position vector and jet direction unit vector of each nozzle (3), the target compensation torque is distributed as the target jet thrust of each nozzle (3); Based on the physical relationship between jet thrust and liquid flow rate, the target jet thrust is converted into the target volume flow rate, and the opening command and pulse duty cycle command of each liquid flow controller (6) are generated.

8. The method according to claim 7, characterized in that, During the thrust distribution process, the control unit (5) performs constraint limiting on the target jet thrust of each nozzle (3): if the calculated target thrust is less than zero, the target thrust of the nozzle (3) is set to zero; if the calculated target thrust is greater than the maximum allowable thrust of the nozzle (3), the target thrust of the nozzle (3) is set to the maximum allowable thrust; the torque difference generated after limiting is compensated by the remaining unsaturated nozzles (3) through secondary distribution.

9. The method according to claim 7, characterized in that, The target compensation torque vector Md(t) is calculated according to the following PID control law: ； In the formula, This is the attitude deviation vector. This is the real-time attitude angle vector. To preset the equilibrium attitude angle vector, Let Kp, Kd, ​​and Ki be the attitude deviation rate vector, and Kp, Kd, ​​and Ki be the proportional gain matrix, differential gain matrix, and integral gain matrix, respectively. The physical relationship between the jet thrust and the liquid flow rate is as follows: ； In the formula, The actual jet thrust of the i-th nozzle (3) Let CT be the target jet thrust of the i-th nozzle (3), and CT be the nozzle thrust coefficient. For the density of the liquid, The actual volumetric flow rate of the i-th nozzle (3) is... For the target volumetric flow rate of the i-th nozzle (3), Let i be the outlet area of ​​the i-th nozzle (3). Let (3) be the outlet diameter of the i-th nozzle; The pulse duty cycle is determined according to the following formula: ； In the formula, Let be the pulse duty cycle of the i-th nozzle (3); The target volumetric flow rate of the i-th nozzle (3); The maximum volumetric flow rate allowed by the i-th liquid flow controller (6) is given.

10. The pulsed liquid jet control system according to claim 2, characterized in that, The control unit (5) also includes a safety protection module, which is used to set the output signals of all liquid flow controllers (6) to zero and output an alarm signal when any of the following conditions are triggered: the pressure of the gas storage tank is lower than the preset safety lower limit, the liquid level of the liquid storage tank (2) is lower than the preset lower limit, the deviation between the feedback flow and the command flow of any liquid flow controller (6) continues to exceed the allowable range for a preset duration, the signal of the attitude acquisition unit (4) is continuously lost for more than the preset number of sampling cycles, or the absolute value of any attitude angle of the platform exceeds the preset safety limit.

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