Multi-parameter cooperative control underwater propeller turnover hoisting management and control method

Abstract

The invention discloses a multi-parameter cooperative control underwater propeller turnover hoisting control method, particularly relates to the field of underwater propeller hoisting, and aims to solve the problem of unstable turnover control of a propeller under tidal current disturbance. The iteration interval of a high-risk section is compressed in time by means of self-adaptive step length mapping, then angle increment and target tension are synchronously corrected before the winding action by means of prediction correction circulation, and three-line linkage of angle adjustment, tension adjustment and environmental safety is achieved. The safety margin diagram is continuously refreshed under the driving of vibration and flow velocity dual information sources, and step length rollback is triggered once a node approaches a warning domain, so that potential oscillation is blocked in a germination stage. The synchronization reliability coefficient runs through the whole process, the winch synchronization quality is evaluated, real-time weighting is performed on step length mapping, and then a convergence path is kept close to a real balance channel. Therefore, the turning-over time is shortened, and the tension fluctuation amplitude is stabilized.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater propeller hoisting, and more specifically, to a method for controlling the turning over and hoisting of an underwater propeller using multi-parameter coordinated control. Background Art

[0002] The underwater propeller rollover and hoisting operation must be completed in an environment with unstable tidal currents and low water visibility. The mechanical relationship between the winch, sling, and propeller changes in real time with the rollover angle. The operator must rely on continuous calculations to select the winch speed and tension distribution to maintain a smooth transition of the propeller's posture. This operation emphasizes angle-force synchronization. Any delay or deviation in the command will directly translate into alternating loads on the steel strand, thereby affecting the integrity of the sealing cover and the safety of the hull.

[0003] However, the current control methods usually use fixed step sizes or empirical step sizes for step-by-step iteration, which does not fully consider the superposition effect of flip curvature mutations and tension phase misalignment. The algorithm convergence path repeatedly swings on the high-order constraint surface, which can easily trigger frequent reverse of the winch, and the tension peak instantaneously coincides with the environmental disturbance, extending the operation window and increasing the risk of cable breakage.

[0004] In order to solve the above problems, a technical solution is now provided. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a multi-parameter coordinated control method for underwater thruster turning over and hoisting control to solve the problem of unstable thruster turning over control under tidal disturbance proposed in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions: S1: Collect the flip angle sequence and the sling tension sequence, perform quadratic difference to calculate the instantaneous curvature, and refine the time interval of the high curvature segment according to the bisection principle, generate an iterative step table and write it into the control unit; S2: The control unit reads the iteration step table and the real-time tension value, uses the least squares prediction method to calculate the next flip angle increment and target tension value, and sends a winch speed command; S3: While the winch is executing the hoisting speed command, the curvature acceleration difference is first obtained based on the angular velocity curve and its time differential. The tension phase drift of the front and rear cables is then calculated using cross-spectral analysis. Both values ​​are input into a preset segmented mapping table to output a synchronization reliability coefficient. If the synchronization reliability coefficient is lower than the threshold, the current iteration step is shortened and the process returns to S2 to refresh the hoisting speed command. S4: The control unit continuously compares the flow rate monitoring data with the propeller vibration spectrum to construct a safety margin map. If a warning area appears in the safety margin map, the iteration step size is shortened and the system returns to S2 for prediction correction. S5: When the synchronization reliability coefficient is stable within the continuous cycle and the safety margin diagram remains positive, the control unit issues a synchronization lifting command to complete the turnaround.

[0007] In a preferred embodiment, step S1 includes the following contents: The sensor is used to collect flip angle and tension data at a fixed initial time interval. The instantaneous curvature is calculated by the second-order difference method. The high curvature segment is identified according to the curvature threshold. The time interval of the high curvature segment is halved to increase the data collection frequency. An iterative step table is generated to record the time interval of each segment. The iterative step table, flip angle sequence and tension sequence are transmitted to the control unit.

[0008] In a preferred embodiment, step S2 includes the following: The control unit extracts the step value of the current time segment from the iterative step table as the current time step, and uses the least squares prediction method based on the historical flip angle sequence and the historical tension sequence to calculate the flip angle increment and target tension value of the thruster at the next moment. The mechanical model is used to calculate the winch speed according to the flip angle increment and the target tension value, and the winch speed is sent as an instruction to the winch to adjust the retraction and extension speed of the sling.

[0009] In a preferred embodiment, step S3 includes the following contents: While the winch is executing the hoisting speed instruction, the control unit monitors the flip angle and tension data in real time, calculates the angular velocity and angular acceleration by differentiating the flip angle sequence, and obtains the curvature acceleration difference by comparing it with the reference angular acceleration.

[0010] In a preferred embodiment, step S3 further includes the following: The phase drift of the tension signals of the front and rear slings is calculated using the cross-spectrum analysis method. The curvature acceleration difference and the tension phase drift are input into a preset segmented mapping table to generate a synchronization reliability coefficient.

[0011] In a preferred embodiment, step S3 further includes the following: When the synchronization reliability coefficient is lower than the preset threshold, the control unit shortens the iteration step and returns to step S2 to recalculate the hoisting speed instruction.

[0012] In a preferred embodiment, step S4 includes the following contents: The control unit collects the flow rate monitoring data in the lifting area in real time through the water flow sensor, and collects the vibration signal on the propeller through the vibration sensor, and then performs frequency domain analysis to generate a vibration spectrum. The flow rate monitoring data and vibration spectrum are used to construct a safety margin diagram. When the safety margin value is lower than the preset warning threshold, the current iteration step will be shortened and step S2 will be triggered to regenerate a new winch speed instruction.

[0013] In a preferred embodiment, step S4 further includes the following: The safety margin diagram has time as the horizontal axis and the safety margin value as the vertical axis, and is determined by calculating the product of the flow rate term ratio and the vibration term.

[0014] In a preferred embodiment, step S5 includes the following contents: The control unit continuously monitors the generated synchronization reliability coefficient and safety margin map, and determines whether the synchronization reliability coefficient remains stable within a predetermined continuous period and whether the safety margin map maintains a positive value within the predetermined continuous period.

[0015] In a preferred embodiment, step S5 further includes the following: When the conditions that the synchronous reliability coefficient remains stable and the safety margin map maintains a positive value are met, the control unit issues a synchronous lifting command to complete the flipping operation and then archives the data for storage.

[0016] The technical effects and advantages of the multi-parameter coordinated control method for underwater propeller turning over and hoisting of the present invention are as follows: The present invention monitors the dynamic state of turning over through the dual perspectives of curvature acceleration difference and tension phase drift, uses adaptive step-size mapping to timely compress the iteration interval of high-risk sections, and then uses the prediction correction cycle to synchronously correct the angle increment and target tension before the winch action, thereby realizing the three-line linkage of angle adjustment, tension adjustment, and environmental safety. The safety margin diagram is continuously refreshed under the drive of the dual signal sources of vibration and flow rate. Once the node approaches the warning domain, the step-size rollback is triggered to block the potential oscillation in the bud stage. The synchronization reliability coefficient runs through the entire process, which not only evaluates the winch synchronization quality, but also gives real-time weight to the step-size mapping, thereby keeping the convergence path close to the real balance channel. The global collaborative logic eliminates the accumulation of reverse instructions and metal fatigue concentration, shortens the turning time, stabilizes the tension fluctuation amplitude, and retains high-resolution working condition files throughout the entire process, providing reliable prior boundaries and decision support for subsequent lifting operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a flow chart of the multi-parameter coordinated control method for underwater thruster turning over and hoisting of the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Example 1: Figure 1The present invention provides a multi-parameter coordinated control method for underwater thruster turning over and hoisting control, including: S1: Collect the flip angle sequence and the sling tension sequence, perform quadratic difference to calculate the instantaneous curvature, and refine the time interval of the high curvature segment according to the bisection principle, generate an iterative step table and write it into the control unit.

[0020] S2: The control unit reads the iteration step table and the real-time tension value, uses the least squares prediction method to calculate the next flip angle increment and target tension value, and sends a winch speed instruction.

[0021] S3: While the winch is executing the hoisting speed command, the curvature acceleration difference is first obtained based on the angular velocity curve and its time differential. Then, the tension phase drift of the front and rear cables is calculated using cross-spectral analysis. Both are input into the preset segmented mapping table to output the synchronization reliability coefficient. If the synchronization reliability coefficient is lower than the threshold, the current iteration step is shortened and the process returns to S2 to refresh the hoisting speed command.

[0022] S4: The control unit continuously compares the flow rate monitoring data with the propeller vibration spectrum to construct a safety margin diagram. If a warning area appears in the safety margin diagram, the iteration step size is also shortened and returns to S2 for prediction correction.

[0023] S5: When the synchronization reliability coefficient is stable within the continuous cycle and the safety margin diagram remains positive, the control unit issues a synchronization lifting command to complete the turnaround.

[0024] The flipping and hoisting operation of an underwater thruster is a highly difficult task to perform in a complex underwater environment, and it is necessary to cope with adverse conditions such as unstable tides and low water visibility. During the hoisting process, the mechanical relationship between the winch, sling and thruster is dynamically adjusted as the flip angle changes in real time. The operator must determine the winch speed and tension distribution through continuous calculations to ensure a smooth transition of the thruster posture. Angle-force synchronization is the core requirement of this operation. If command delays or deviations occur, the steel strands may be subjected to alternating loads, thereby threatening the integrity of the sealing cover and the safety of the hull. Traditional methods mostly use fixed step sizes or empirical step sizes for control, which fail to fully consider the superposition effect of sudden changes in flipping curvature and tension phase misalignment, which can easily cause problems such as unstable algorithm convergence and frequent winch reversal, extending operation time and increasing the risk of cable breakage.

[0025] This paper proposes a multi-parameter coordinated control method for underwater propulsion rollover and hoisting. By collecting real-time rollover angle and sling tension data, combined with adaptive step-size adjustment and predictive correction technology, it achieves coordinated optimization of angle adjustment, tension regulation, and environmental safety. Step S1, as the starting point of the entire process, is responsible for generating an iterative step-size table, providing a precise time reference for subsequent steps and ensuring that control instructions can adapt to the dynamic changes in the rollover process.

[0026] Step S1 includes the following contents: S1-1, data acquisition: First, angle sensors installed on the thruster and tension sensors on the sling collect the thruster's roll angle sequence and the sling's tension sequence in real time. The thruster's roll angle sequence reflects the thruster's posture changes during the lifting process, while the sling's tension sequence reflects the force applied to the sling. During the acquisition process, data is recorded at fixed initial intervals, such as every 0.1 seconds, to form discrete datasets of roll angle sequences and tension sequences. These datasets provide the raw input for subsequent instantaneous curvature calculation and high-curvature segment identification.

[0027] S1-2, instantaneous curvature calculation: In order to quantify the rate of change of the flip angle sequence, the instantaneous curvature is calculated using the quadratic difference method. The instantaneous curvature reflects the acceleration of the flip angle change and is used to identify the key sections of dynamic changes during the propeller flip process. The specific calculation process is: For each time point in the flip angle sequence, the angle value at that time point is subtracted from the angle value at the previous time point to obtain the first difference. The angle value at the next time point is then subtracted from the angle value at that time point to obtain the second difference. The difference between the first and second differences is then divided by the square of the initial time interval to obtain the instantaneous curvature value at that time point. This method generates an instantaneous curvature sequence by numerically approximating the second-order rate of change of angle changes.

[0028] The quadratic difference method effectively captures the acceleration trends of the rollover angle sequence and better reflects the intensity of the dynamic process than single differences. Calculating the instantaneous curvature sequence provides a quantitative basis for identifying subsequent high-curvature sections, ensuring that the control system can accurately determine the dynamic characteristics of the thruster rollover.

[0029] S1-3, high curvature segment identification and step size refinement: Based on the instantaneous curvature sequence, a curvature threshold, such as 0.05 radians per second squared, is set to distinguish between high and low curvature segments. For each time point in the instantaneous curvature sequence, if the instantaneous curvature value at that time point exceeds the curvature threshold, the time point is considered to be in the high curvature segment, indicating a dramatic change in the flip angle. If the instantaneous curvature value does not exceed the curvature threshold, the time point is considered to be in the low curvature segment, indicating a smooth change in the flip angle. For high curvature segments, the current time interval is halved, for example, from 0.1 seconds to 0.05 seconds, to increase the frequency of data acquisition and control. For low curvature segments, the initial time interval remains unchanged.

[0030] By using curvature thresholds to distinguish between high and low curvature sections, the temporal resolution can be adjusted based on the actual dynamic characteristics of the thruster rollover process. Refining the step size in high-curvature sections improves data acquisition density and control precision, ensuring timely response during periods of drastic rollover angle changes. Maintaining a larger step size in low-curvature sections reduces unnecessary computational burden and improves overall processing efficiency.

[0031] S1-4, iterative step table generation: Based on the results of high curvature segment identification and step size refinement, an iterative step size table is generated to record the time step for each time segment. The iterative step size table is presented as a pair of time segments and corresponding step sizes, for example, a step size of 0.1 seconds for one time segment and 0.05 seconds for another time segment. The generation process is to traverse the instantaneous curvature sequence and associate the high or low curvature attribute of each time point with its corresponding time step in chronological order. This is organized into a continuous list of time-step pairs to form a complete iterative step size table.

[0032] The iterative step table realizes the dynamic allocation of time resolution and clearly records the control requirements of each time segment during the thruster turning process.

[0033] S1-5, data writing control unit: The generated iteration step table, flip angle sequence, and tension sequence are transmitted to the control unit. Based on the iteration step table, the control unit determines the calculation frequency for each time segment and uses the flip angle sequence and tension sequence to predict the thruster's turning state and generate control instructions. This transmission process ensures that the time-step pairs in the iteration step table, the angle values ​​in the flip angle sequence, and the tension values ​​in the tension sequence are transmitted in chronological order, supporting real-time processing by the control unit.

[0034] The iterative step table, along with the flip angle sequence and tension sequence, is fed into the control unit, providing comprehensive information for thruster rollover control. The iterative step table sets a dynamic time base for the control unit, while the flip angle sequence and tension sequence provide real-time status data, enabling the control unit to adjust instructions based on actual dynamics, thereby improving the safety and efficiency of lifting operations.

[0035] Step S1 collects the flip angle sequence and the cable tension sequence and generates an iterative step table based on the adaptive adjustment of the instantaneous curvature, providing a dynamic time reference for subsequent control. However, relying solely on step adjustment is not enough to cope with the complex dynamic relationship between flip angle and tension during the flipping process, as well as the influence of environmental factors such as tidal disturbances. Step S2, as the core link of the control process, requires the use of real-time data and predictive models to generate accurate winch speed instructions to ensure a smooth transition of the propeller attitude and stable cable tension.

[0036] The processing logic in step S2 is designed to precisely regulate the propeller rollover process through the control unit, using input parameters to generate a winch speed command to ensure coordinated control of the rollover angle and sling tension. The following is a detailed description of the processing process.

[0037] Step S2 includes the following contents: S2-1, determine the current time step: The control unit first extracts the step value corresponding to the current time segment from the iteration step table, referred to as the current time step. The iteration step table, generated in step S1, records the calculation step size for each time segment and is used to guide the frequency of control command updates. The determination of the current time step directly impacts the temporal resolution of the prediction model and the cadence of hoisting speed commands. By reading the pre-set step value, the control unit can adjust the calculation and control frequency according to the dynamic requirements of the turning process, ensuring the system's timely response to changes in thruster attitude.

[0038] By using the predetermined values ​​in the iterative step table to determine the current time step, the control rhythm can be flexibly adjusted according to the different stages of the turning process, avoiding response delays or overly frequent calculations caused by fixed step sizes, thereby improving the adaptability and efficiency of the control system.

[0039] S2-2, predict the flip angle increment and target tension value at the next moment: Based on the historical flip angle sequence and the historical tension sequence, the control unit uses the least squares prediction method to calculate the flip angle increment and target tension value at the next moment. The historical flip angle sequence records the flip angle of the propeller at the past time point; the historical tension sequence records the tension value of the sling at the past time point, both of which are provided by step S1. The flip angle increment represents the change in the flip angle of the propeller at the next moment relative to the current moment; the target tension value represents the ideal tension value that the sling should reach at the next moment, in Newtons. The calculation idea of ​​the least squares prediction method is to find the mathematical model that can best describe the relationship between these data by analyzing the changing trends of the historical flip angle sequence and the historical tension sequence. Specifically, this method compares the deviation between the predicted value and the historical data, adjusts the sum of the squares of all deviations to the minimum, determines the characteristic coefficient of the model, and thus calculates the predicted value at the next moment.

[0040] The least-squares prediction method fully leverages the dynamic information in historical roll angle and tension sequences, accurately capturing the interplay between thruster roll trends and tension changes. This method provides forward-looking predictions based on trend analysis of historical data, ensuring smooth transitions in thruster attitude and stable control of cable tension, thereby improving system reliability and accuracy.

[0041] S2-3, calculate the winch speed: The control unit uses a mechanical model to calculate the required hoisting speed based on the predicted flip angle increment and the target tension value. The mechanical model comprehensively considers the mass of the propeller, the stiffness of the sling, and the geometric relationship during the flipping process. The calculation process first multiplies the predicted flip angle increment by the effective length of the sling to obtain the displacement of the sling that needs to be adjusted during the propeller flipping process; then, this displacement is divided by the current time step to obtain the basic hoisting speed. Next, based on the target tension value, the basic hoisting speed is adjusted using an experimentally calibrated correction factor to ensure that the tension of the sling can be maintained within the predicted target range. This adjustment takes into account the nonlinear relationship between tension and speed, ensuring that the control instructions can achieve both changes in the flip angle and meet the stability requirements of the tension.

[0042] By calculating the winch speed using a mechanical model, the predicted flip angle increment and target tension value can be converted into specific execution instructions. This method combines physical laws with experimental data to ensure that the calculated results meet the motion requirements of the propeller while maintaining the dynamic balance of the sling tension, thereby ensuring the safety and control accuracy of the flip process.

[0043] S2-4, send winch speed command: The control unit sends the calculated hoisting speed as a command to the winch, which guides the adjustment of the cable retraction and extension speed, thereby controlling the propeller's turning process. The hoisting speed command, measured in meters per second, directly drives the hoisting machine. This command transmission process ensures real-time communication between the control unit and the actuator, enabling the system to adjust the propeller's posture and cable tension in real time based on the calculated results.

[0044] There is a close contextual connection between step S2 and step S1 and step S3. The iterative step table, historical flip angle sequence and historical tension sequence generated by step S1 are directly used as input parameters of step S2 to ensure the continuity and consistency of the data source. The hoisting speed instruction calculated by step S2 is passed to step S3 for synchronization evaluation during execution. Step S3 calculates the synchronization reliability coefficient by analyzing the angular velocity curve and the tension phase drift. If the synchronization reliability coefficient is lower than the preset threshold, indicating that the current control effect is insufficient, step S3 will shorten the current time step and require step S2 to recalculate the hoisting speed instruction. This feedback mechanism enables step S2 to dynamically adjust the control instructions according to the actual execution situation to ensure the real-time and stability of the turning process.

[0045] Step S2 uses the iterative step table and real-time tension values ​​to calculate the next-moment roll angle increment and target tension value using the least squares prediction method, and generates a winch speed command. However, due to factors such as tidal disturbances, water damping, and system response delays, the winch speed command may deviate from expectations during actual execution, resulting in impaired synchronization between the roll angle and tension distribution, which in turn affects the stability of the thruster's attitude. Therefore, step S3, as a key link in real-time monitoring and feedback, quantifies the synchronization effect by evaluating the curvature acceleration difference and tension phase drift, and adjusts the iterative step size when necessary to ensure the smoothness and safety of the rollover process.

[0046] The processing logic in step S3 ensures the synchronization and stability of the propeller's turning process by monitoring and evaluating the winch's effectiveness in executing the winch speed command in real time. Based on real-time data and pre-set rules, the control unit calculates key indicators and dynamically adjusts control parameters to achieve a smooth transition of the propeller's attitude and stable control of the cable tension. The following details the processing process.

[0047] Step S3 includes the following contents: S3-1, calculate the curvature acceleration difference: The control unit first calculates the instantaneous angular velocity and angular acceleration using the flip angle sequence. The flip angle sequence records the flip angle of the propeller at different time points. The instantaneous angular velocity is obtained by analyzing the rate of change of the flip angle sequence over time, which indicates the speed of the propeller flipping. The angular acceleration is obtained by calculating the rate of change of the instantaneous angular velocity over time, which indicates the magnitude of the propeller flip acceleration. Next, the reference angular acceleration is introduced. This value comes from the next flip angle increment calculated based on the least squares prediction method in step S2, reflecting the angular acceleration that the propeller should reach under ideal conditions. By subtracting the actual calculated angular acceleration from the reference angular acceleration, the curvature acceleration difference is obtained. The curvature acceleration difference represents the deviation between the actual execution effect and the prediction model, and is used to evaluate the synchronization of the propeller flipping process.

[0048] Calculating the curvature acceleration difference quantifies the degree of deviation between the actual motion state and the expected state during the thruster rollover. Combining the real-time acquired rollover angle sequence with the predicted reference angular acceleration ensures that the monitoring results are both accurate and forward-looking, providing a reliable basis for subsequent synchronization assessments and effectively improving the control system's responsiveness.

[0049] S3-2, calculate the tension phase drift: The control unit performs frequency domain analysis on the tension sequences of the front and rear cables and calculates the tension phase drift. The tension sequences of the front and rear cables record their tension values ​​at different time points. First, the control unit uses cross-spectral analysis to convert the tension sequences of the front and rear cables into frequency domain signals, generating a cross-spectral function. The cross-spectral function describes the correlation between the tension signals of the front and rear cables at different frequencies. Next, by analyzing the cross-spectral function, the tension phase drift is calculated, representing the phase difference between the tension signals of the front and rear cables in the frequency domain. The magnitude of the tension phase drift reflects the degree of synchronization between the tension changes of the front and rear cables. A smaller phase drift indicates a higher degree of synchronization, while a smaller phase drift indicates a synchronization deviation.

[0050] Cross-spectral analysis is a signal processing technique used to analyze the correlation and phase relationship between two signals. By calculating the cross-spectrum of two signals—the conjugate product of their Fourier transforms—it reveals their interaction at different frequencies. The cross-spectrum provides information on the amplitude and phase differences between the signals, allowing identification of signal synchronization, delays, or phase shifts. This method is widely used in fields such as vibration analysis, acoustics, and biomedicine to assess system dynamics and detect abnormal conditions.

[0051] Calculating tension phase drift assesses the synchronization of tension changes between the front and rear cables through frequency-domain analysis, overcoming the limitations of relying solely on time-domain analysis. This method captures the dynamic characteristics of tension changes, ensuring a comprehensive assessment of synchronization and ultimately improving the accuracy and stability of tension control during thruster rollover.

[0052] S3-3, generate synchronous reliability coefficient: The control unit inputs the curvature acceleration difference and tension phase drift into a preset segmented mapping table to generate a synchronization reliability coefficient. The synchronization reliability coefficient is a dimensionless value ranging from 0 to 1, with values ​​closer to 1 indicating greater synchronization during the thruster rollover process. The segmented mapping table divides the curvature acceleration difference and tension phase drift into multiple intervals based on their amplitude ranges, and assigns a corresponding synchronization reliability coefficient to each interval. For example, when both the curvature acceleration difference and tension phase drift are within the preset ideal range, the synchronization reliability coefficient is 1. When either parameter exceeds the ideal range, the synchronization reliability coefficient decreases by a preset ratio.

[0053] In this invention, a "segmented mapping table" is a pre-defined tool used to convert curvature acceleration difference and tension phase drift into synchronization reliability coefficients to evaluate the synchronization effectiveness of the turning process. Specifically, this function is achieved by dividing the amplitude of the curvature acceleration difference and tension phase drift into multiple intervals and assigning a corresponding synchronization reliability coefficient value to each interval. This mapping relationship is established based on experimental data and system characteristic calibration to ensure the objectivity and consistency of the evaluation results. For example, when the curvature acceleration difference and tension phase drift are both within the ideal range, the synchronization reliability coefficient is set to 1, indicating optimal synchronization. However, as the difference or drift gradually increases, the synchronization reliability coefficient decreases proportionally, reaching a minimum of 0, reflecting a decrease in synchronization. This segmented mapping method not only simplifies the synchronization evaluation process, but also enables the control unit to quickly and accurately determine the synchronization status of the turning process and adjust system operation in real time based on the results, thereby improving overall performance and reliability.

[0054] Generating a synchronization reliability coefficient combines the curvature acceleration difference and tension phase drift into a single quantitative indicator, facilitating rapid assessment of the synchronization effectiveness of the rollover process. A segmented mapping table ensures objectivity and consistency in the evaluation process, enabling the control unit to efficiently make decisions based on the synchronization reliability coefficient, thereby optimizing the control accuracy of the thruster rollover process.

[0055] S3-4, determine and adjust the iteration step size: The control unit compares the synchronization reliability coefficient with a preset synchronization reliability coefficient threshold, for example, the threshold is set to 0.8. If the synchronization reliability coefficient is greater than or equal to the threshold, it indicates that the execution effect of the current propeller turning process is good. The control unit maintains the current iteration step unchanged and continues to execute subsequent steps. The iteration step is provided by the iteration step table generated in step S1. If the synchronization reliability coefficient is less than the threshold, it indicates that the synchronization is insufficient. The control unit shortens the current iteration step, for example, halves its value, and returns to step S2 to recalculate the turning angle increment, target tension value, and winch speed instruction.

[0056] By comparing the synchronization reliability coefficient with a threshold, real-time monitoring and dynamic adjustment of the synchronicity of the turning process are achieved. This feedback mechanism can quickly shorten the iteration step size when synchronicity decreases, increasing the update frequency of control instructions, thereby ensuring smooth transition of the thruster attitude and stable control of the tension of the front and rear cables, improving the adaptability and reliability of the system.

[0057] There is a close technical connection between step S3, step S2 and step S4. The winch speed instruction generated by step S2 is monitored and evaluated in real time by step S3 during execution to ensure the synchronization of the propeller turning over process. Step S3 generates a synchronization reliability coefficient by calculating the curvature acceleration difference and the tension phase drift, and adjusts the iteration step size when the synchronization is insufficient and returns to step S2 to recalculate the control parameters, forming a dynamic feedback loop to ensure the real-time and stability of the control system. At the same time, the execution result of step S3 provides support for step S4. Step S4 constructs a safety margin diagram by comparing the flow rate monitoring data with the propeller vibration spectrum to further evaluate the safety of the turning over process, and also shortens the iteration step size when necessary and returns to step S2 for prediction correction.

[0058] Since relying solely on angle and tension control cannot fully assess the real-time effects of environmental factors, particularly the potential safety hazards caused by the combined effects of flow rate changes and propeller vibration, step S4 incorporates flow rate monitoring data and propeller vibration spectrum to construct a safety margin map to quantify risk and trigger iterative step size adjustments when necessary. This forms a closed-loop connection with the prediction and correction in step S2, ensuring the safety and stability of the operation.

[0059] Step S4 includes the following contents: S4-1, data collection: The control unit first uses a water flow sensor to collect the water flow velocity in the lifting area in real time and generate flow rate monitoring data. Flow rate monitoring data reflects the dynamic changes in the tide in the operating environment and is an important basis for assessing the impact of the environment on the propeller's rollover. Simultaneously, a vibration sensor installed on the propeller collects the propeller's vibration signal, and the vibration signal is analyzed in the frequency domain to generate a vibration spectrum. The vibration spectrum describes the vibration intensity of the propeller at different frequencies and is used to quantify the vibration characteristics of the propeller during the rollover process. The purpose of collecting flow rate monitoring data and vibration spectrum is to comprehensively monitor the environment and equipment status and provide real-time input for subsequent safety assessments.

[0060] S4-2, construct safety margin diagram: The control unit uses flow rate monitoring data and the vibration spectrum to construct a safety margin chart. The safety margin chart is a dimensionless numerical value that comprehensively assesses the safety status of the current operation. The calculation of the safety margin takes into account the dual effects of flow rate and vibration. First, the flow rate term is calculated by comparing the real-time flow rate monitoring data with a preset safety flow rate threshold to determine the flow rate margin ratio. The safety flow rate threshold is an upper flow rate limit calibrated based on the operating environment and propeller tolerance. Second, the vibration term is calculated by comparing the energy difference within a specific frequency range of the propeller's real-time vibration spectrum with a reference vibration spectrum, which is a baseline vibration level calibrated under ideal, undisturbed conditions. Finally, the flow rate and vibration terms are multiplied to determine the safety margin value. A safety margin value closer to 1 indicates a safer operation. A decreasing safety margin value indicates that the flow rate or vibration is approaching a dangerous level.

[0061] The calculation of the safety margin, determined by multiplying the velocity term with the vibration term, has both strong theoretical basis and practical significance, as this method comprehensively considers the dual risks of environmental disturbances and the dynamic response of the equipment during underwater propulsion turning and lifting operations. The velocity term quantifies the threat posed by tidal disturbances to the lifting operation by calculating the margin ratio between real-time velocity monitoring data and a safety velocity threshold. When the velocity approaches or exceeds the safety threshold, the velocity term approaches zero, reflecting the increased environmental risk. The vibration term assesses the dynamic stability of the propulsion during turning by comparing the energy deviation between the propeller vibration spectrum and a reference vibration spectrum. When the vibration energy significantly exceeds the baseline, the vibration term decreases, indicating that the equipment may be at risk of instability or fatigue. The multiplication of the two to form a safety margin effectively captures the combined risks of the interaction between velocity and vibration. For example, high velocity can amplify the negative effects of vibration, while abnormal vibration can trigger structural resonance at specific velocity levels. This product form, based on the engineering principle of risk superposition, ensures that the safety margin decreases rapidly when any factor exceeds its limit, triggering control adjustments. Meanwhile, it maintains a high value when both factors are safe, reflecting the stability of the operation. Experimental calibration and mechanical analysis further validated the reliability of this method, making it a scientific basis for assessing operational safety.

[0062] A safety margin diagram quantifies the impact of flow velocity and vibration into a single safety indicator, allowing the control unit to quickly determine the safety status of the operation. This system simultaneously considers environmental and equipment factors, ensuring the control unit's comprehensive awareness of potential risks, thus providing reliable safety assurance for thruster turning and hoisting operations.

[0063] S4-3, Warning Area Identification: The control unit continuously monitors the safety margin value in the safety margin map and compares it with a preset warning threshold. The warning threshold is a pre-calibrated lower safety limit, such as 0.2, which defines the warning zone in the safety margin map. When the safety margin value falls below the warning threshold, the current operation has entered the warning zone, indicating that the flow rate or vibration is approaching dangerous levels, which may pose a threat to the safety of the thruster rollover process.

[0064] By setting warning thresholds and identifying warning zones, the control unit can promptly detect potential safety hazards. This early warning mechanism ensures that the control unit can take action before risks escalate, effectively preventing unexpected events during thruster rollover and improving operational safety and reliability.

[0065] S4-3, iterative step size adjustment: The control unit dynamically adjusts the iteration step size based on the monitoring results of the safety margin diagram and forms a feedback loop with step S2. If the safety margin value is greater than or equal to the warning threshold, it indicates that the operating status is safe, and the control unit keeps the current iteration step size unchanged and continues to execute the existing control process. The iteration step size is provided by the iteration step size table generated by step S1. If the safety margin value is lower than the warning threshold, it indicates that the warning area has been entered. The control unit shortens the current iteration step size, for example, halve it, to increase the update frequency of the control instructions and slow down the response of the turning action to environmental disturbances. The adjusted iteration step size is written into the iteration step size table of the control unit. The control unit re-executes step S2 based on the updated iteration step size table and the real-time tension value, that is, uses the least squares prediction method to calculate the next flip angle increment, the target tension value, and generates a new winch speed instruction.

[0066] Step S4 forms a close technical connection with steps S1, S2, and S5. The iterative step length table generated by step S1 provides the initial calculation step length for step S4. When step S4 detects an insufficient safety margin, it adjusts the iterative step length and passes the adjusted iterative step length to step S2, triggering the recalculation of the control command, forming a dynamic feedback loop between environmental disturbances and control commands. At the same time, step S4 uses the monitoring results of the safety margin diagram to provide a safety prerequisite for the synchronous lifting command of step S5, ensuring that the turning operation is completed when the safety margin remains positive.

[0067] The aforementioned steps S1 to S4 generate an iterative step table by collecting the flip angle sequence and the sling tension sequence, and combine the least squares prediction method, the synchronous reliability coefficient and the safety margin diagram to achieve dynamic control and safety monitoring of the flipping process. These steps ensure the coordination of the propeller flip angle and the sling tension by adjusting the iterative step and the winch speed instruction in real time, and continuously evaluate the environmental disturbance and equipment vibration. However, simple real-time adjustment and monitoring are not enough to ensure the ultimate stability and safety of the entire flipping process, especially in an environment with unstable tides and low water visibility. The flipping operation can only be completed safely when specific conditions are met. Step S5, as the end point of the entire process, is responsible for judging whether the flipping process has reached a safe and stable state, and completing the flipping when the conditions are met, while archiving the operation data to support subsequent optimization.

[0068] Step S5 includes the following contents: S5-1, monitoring synchronization reliability factor and safety margin diagram: The control unit continuously collects and analyzes data to monitor the synchronization reliability coefficient and safety margin diagram in real time to assess the synchronization and safety of the thruster turning process. Within each cycle, the continuous change amplitude of the synchronization reliability coefficient is calculated to determine whether it is always less than or equal to the preset fluctuation amplitude threshold within the preset number of consecutive cycles, thereby confirming the stability of the synchronization reliability coefficient. At the same time, the control unit checks whether the value in the safety margin diagram is always positive within the same number of consecutive cycles to verify the safety status of the operation. Only when the fluctuation amplitude of the synchronization reliability coefficient meets the stability condition and the value of the safety margin diagram remains positive, the control unit will confirm that the thruster turning process is in a safe and stable state. Otherwise, it will continue monitoring or return to the previous step for adjustment.

[0069] Through real-time monitoring of the synchronization reliability coefficient and safety margin diagram, the control unit can fully grasp the dynamic performance of the thruster turning process, ensuring that both synchronization and safety meet the expected requirements in complex environments.

[0070] S5-2, determine the conditions for turning over: The control unit simultaneously evaluates the stability of the synchronous reliability coefficient and the positive state of the values ​​in the safety margin diagram in each cycle to determine whether the propeller turning process has met the completion requirements. The judgment process first checks the variation range of the synchronous reliability coefficient within a preset number of consecutive cycles by calculating the difference between its maximum and minimum values ​​and comparing it with a preset fluctuation amplitude threshold. If the difference is less than or equal to the threshold, the synchronous reliability coefficient is considered stable. Secondly, it checks whether the values ​​in the safety margin diagram are all positive within the same number of consecutive cycles. By comparing the relative size of the values ​​in each cycle with zero one by one, it ensures that all are greater than zero. Only when the stability condition of the synchronous reliability coefficient and the positive value condition of the safety margin diagram are simultaneously met within a continuous preset number of cycles, the control unit determines that the propeller turning process has reached a safe and stable state and enters the subsequent process. If any condition is not met, return to step S3 to adjust the synchronization of the flip angle sequence and the sling tension sequence, or return to step S4 to correct the matching degree of the flow rate monitoring data and the vibration spectrum until the conditions are met.

[0071] Using dual validation criteria—synchronous reliability coefficient stability and positive safety margin diagram values—the control unit accurately determines the timing of the thruster rollover process, ensuring the operation is executed when both synchronization and safety requirements are met. This judgment mechanism, validated through multi-dimensional data, reduces the risk of misjudgment and improves the accuracy and safety of thruster rollover and hoisting operations.

[0072] S5-3, issue synchronous lifting command: When the stability of the synchronous reliability coefficient and the positive state of the safety margin diagram are simultaneously satisfied within a preset number of continuous cycles, the control unit generates and issues a synchronous lifting instruction to coordinate the action of the winch to complete the turning and lifting operation of the propeller. The synchronous lifting instruction is based on the next flip angle increment and target tension value predicted in step S2, and the specific instruction content is determined by calculating the tension adjustment required for each sling in the next cycle and the retraction and extension speed of the winch. The instruction includes a winch speed instruction and a tension distribution parameter, wherein the winch speed instruction is calculated based on the relationship between the flip angle increment and time, and the tension distribution parameter is determined based on the distribution ratio of the target tension value among the slings. The control unit sends these instructions to the winch, instructing it to adjust the retraction and extension speed of each sling so that the propeller can be smoothly lifted and lowered to the target position after the turning is completed, ensuring the coordination and stability of the entire process.

[0073] By generating and issuing synchronized lifting and lowering commands, the control unit precisely controls the winch, ensuring the thruster smoothly ascends and descends to the target position after turning. This command generation and execution mechanism, through pre-calculation and real-time coordination, ensures synchronized and smooth movements, improving the efficiency and safety of thruster turning and hoisting operations.

[0074] S5-4, Data Archiving: After the thruster flipping process is completed, the control unit stores the relevant data in the storage unit to support subsequent analysis and optimization. The stored data includes the flipping angle sequence, the sling tension sequence and the iteration step table. The flipping angle sequence records the angle change of the thruster at each time point during the flipping process, in radians, and is generated by sorting out the calculation results of steps S2 and S3; the sling tension sequence records the tension change of the front and rear slings at each time point, which is formed by summarizing the monitoring data of step S3; the iteration step table records the iteration step of each time segment, which comes from the adjustment process of steps S3 and S4. The control unit organizes these data in a timestamp-aligned manner to ensure that the correspondence between each set of data is clear and traceable. After being stored in the storage unit, a high-resolution working condition file is formed for reference and performance evaluation of subsequent lifting operations.

[0075] Step S5 directly utilizes the synchronization reliability coefficient provided by step S3 and the safety margin value provided by step S4. By judging stability and positive values, it determines the timing of the turnaround completion, ensuring that synchronization and safety requirements are met. Furthermore, the synchronization lifting command generated by step S5 relies on the flip angle increment and target tension value predicted in step S2, while the archived data provides a reference for optimizing the initial conditions in step S1. This seamless technical process, through data transmission and verification, ensures the stability, safety, and continuity of the thruster turnaround and hoisting operation, meeting the high standards required for operations in complex environments.

[0076] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0077] It should be noted that the system of the present invention can be deployed on the device itself to realize embedded applications, and can also be run on a PC or other terminal with a user interface, thereby meeting a variety of hardware environments and usage requirements.

[0078] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

[0079] It should be noted that, in this document, if there are relational terms such as first and second, etc., they are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article or device. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0080] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A multi-parameter coordinated control method for underwater thruster turning over and lifting, characterized in that: Including steps: S1: Collect the flip angle sequence and the sling tension sequence, perform quadratic difference to calculate the instantaneous curvature, and refine the time interval of the high curvature segment according to the bisection principle, generate an iterative step table and write it into the control unit; S2: The control unit reads the iteration step table and the real-time tension value, uses the least squares prediction method to calculate the next flip angle increment and target tension value, and sends a winch speed command; S3: While the winch is executing the hoisting speed command, the curvature acceleration difference is first obtained based on the angular velocity curve and its time differential. The tension phase drift of the front and rear cables is then calculated using cross-spectral analysis. Both values ​​are input into a preset segmented mapping table to output a synchronization reliability coefficient. If the synchronization reliability coefficient is lower than the threshold, the current iteration step is shortened and the process returns to S2 to refresh the hoisting speed command. S4: The control unit continuously compares the flow rate monitoring data with the propeller vibration spectrum to construct a safety margin map. If a warning area appears in the safety margin map, the iteration step size is shortened and the system returns to S2 for prediction correction. S5: When the synchronization reliability coefficient is stable within the continuous cycle and the safety margin diagram remains positive, the control unit issues a synchronization lifting command to complete the turnaround.

2. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 1 is characterized in that: Step S1 includes the following contents: The sensor is used to collect flip angle and tension data at a fixed initial time interval. The instantaneous curvature is calculated by the second-order difference method. The high curvature segment is identified according to the curvature threshold. The time interval of the high curvature segment is halved to increase the data collection frequency. An iterative step table is generated to record the time interval of each segment. The iterative step table, flip angle sequence and tension sequence are transmitted to the control unit.

3. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 2 is characterized in that: Step S2 includes the following contents: The control unit extracts the step value of the current time segment from the iterative step table as the current time step, and uses the least squares prediction method based on the historical flip angle sequence and the historical tension sequence to calculate the flip angle increment and target tension value of the thruster at the next moment. The mechanical model is used to calculate the winch speed according to the flip angle increment and the target tension value, and the winch speed is sent as an instruction to the winch to adjust the retraction and extension speed of the sling.

4. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 3 is characterized in that: Step S3 includes the following contents: While the winch is executing the hoisting speed instruction, the control unit monitors the flip angle and tension data in real time, calculates the angular velocity and angular acceleration by differentiating the flip angle sequence, and obtains the curvature acceleration difference by comparing it with the reference angular acceleration.

5. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 4 is characterized in that: Step S3 also includes the following: The phase drift of the tension signals of the front and rear slings is calculated using the cross-spectrum analysis method. The curvature acceleration difference and the tension phase drift are input into a preset segmented mapping table to generate a synchronization reliability coefficient.

6. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 5 is characterized in that: Step S3 also includes the following: When the synchronization reliability coefficient is lower than the preset threshold, the control unit shortens the iteration step and returns to step S2 to recalculate the hoisting speed instruction.

7. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 6 is characterized in that: Step S4 includes the following contents: The control unit collects the flow rate monitoring data in the lifting area in real time through the water flow sensor, and collects the vibration signal on the propeller through the vibration sensor, and then performs frequency domain analysis to generate a vibration spectrum. The flow rate monitoring data and vibration spectrum are used to construct a safety margin diagram. When the safety margin value is lower than the preset warning threshold, the current iteration step will be shortened and step S2 will be triggered to regenerate a new winch speed instruction.

8. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 7 is characterized in that: Step S4 also includes the following: The safety margin diagram has time as the horizontal axis and the safety margin value as the vertical axis, and is determined by calculating the product of the flow rate term ratio and the vibration term.

9. The method for controlling and managing the turning over and hoisting of an underwater propeller with multi-parameter coordinated control according to claim 8 is characterized in that: Step S5 includes the following contents: The control unit continuously monitors the generated synchronization reliability coefficient and safety margin map, and determines whether the synchronization reliability coefficient remains stable within a predetermined continuous period and whether the safety margin map maintains a positive value within the predetermined continuous period.

10. The multi-parameter coordinated control method for underwater propulsion turning over and hoisting according to claim 9 is characterized in that: Step S5 also includes the following: When the conditions that the synchronous reliability coefficient remains stable and the safety margin map maintains a positive value are met, the control unit issues a synchronous lifting command to complete the flipping operation and then archives the data for storage.

Images