CN109110073A - Method for early warning, device and the equipment of marine floating type works parameter resonance movement - Google Patents
Method for early warning, device and the equipment of marine floating type works parameter resonance movement Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
- B63B39/005—Equipment to decrease ship's vibrations produced externally to the ship, e.g. wave-induced vibrations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
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- G05D1/08—Control of attitude, i.e. control of roll, pitch, or yaw
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- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
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- G05D1/08—Control of attitude, i.e. control of roll, pitch, or yaw
- G05D1/0875—Control of attitude, i.e. control of roll, pitch, or yaw specially adapted to water vehicles
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Abstract
The present invention provides method for early warning, device and the equipment of the movement of marine floating type works parameter resonance, comprising: obtains the motor message in the different freedom degrees of the marine floating type works acquired in real time；By the different motion signal when count one by one according to linear superposition with obtain close signal when count evidence one by one；According to it is described close signal when count one by one according to generate it is described close signal instantaneous frequency change over time instantaneous frequency when count evidence one by one；It is counted one by one when from the instantaneous frequency and picks out frequency discontinuity in；Wherein, the frequency discontinuity be parameter resonance move occur when as caused by the frequency multiplication relationship between the motor message at least two freedom degrees；It is calculated at the time of parameter resonance movement occurs according to the frequency discontinuity for progress early warning.The present invention realizes the advanced early warning of parameter resonance movement using more efficient algorithm and less installation cost, can consume seldom energy when the initial stage motion amplitude that parameter resonance occurs is smaller efficiently to evade parameter resonance movement.
Description
Technical Field
The invention relates to the field of ship and ocean engineering, in particular to an early warning method, a device, a storage medium and equipment for detecting parameter resonance motion of an ocean floating structure.
Background
When excited by waves, marine floating structures such as ships, ocean platforms, offshore floating fans and the like can generate nonlinear parametric resonance motions besides conventional wave excitation motions, such as: the parameter rolling motion of container ships and luxury mail ships, the parameter pitching motion of SPAR platforms and offshore floating fans, and the like. When the parameter resonance occurs, the large and violent movement and even instability and overturning of the floating structure can be accompanied, and great personnel and property losses are caused, such as: the container ship loses the case, SPAR platform and offshore floating type fan under the large-amplitude parameter pitching motion, and the like under the large-amplitude parameter rolling motion. Therefore, measures are urgently needed to avoid the occurrence of parameter resonance.
At present, active (an active anti-rolling water tank, an anti-rolling fin, a dynamic positioning system and the like) and passive devices (a passive anti-rolling water tank, a bilge keel, a heave plate and the like) are additionally arranged on an ocean floating structure to effectively avoid wave-excited motion. However, these devices have limited evasion effects for parametric resonance motions that are more severe than conventional wave-excited motions. According to the characteristic of the parameter resonance movement, when the initial stage just meets the parameter resonance condition, the movement amplitude is smaller. Therefore, if it is possible to warn at the initial stage of occurrence of the parameter resonance and to change the condition for achieving the resonance by using the apparatus, it is possible to efficiently avoid the parameter resonance exercise by consuming little energy. Therefore, the advanced early warning device of the ocean floating structure has important significance on the safety of the advanced early warning device.
The Chinese patent application 'a ship track tracking and predicting control method for actively inhibiting parameter rolling' (publication number: CN104881040A) proposes that when the ship generates parameter rolling, a rudder is adopted to inhibit the parameter rolling on the premise of sacrificing the ship track tracking performance as little as possible. In the invention, the rudder is stabilized when large parameter resonance motion occurs, a large amount of energy is consumed, and the track tracking performance of the ship is influenced. Therefore, the importance of performing advanced early warning on the parameter resonance motion and inhibiting when the motion amplitude is small can be seen. The inventor of Korean patent 'parameter rolling prevention apparatus and method for vessel' (publication: KR100827396B1) proposed a method and device for early warning of vessel parameter rolling and employs a rudder to suppress the parameter rolling. The wave monitoring equipment (wave monitoring device) required in the early warning device is not easy to obtain, and the application has certain limitation, which is obviously different from the parameter resonance advanced early warning only by adopting the conveniently obtained motion signal in the invention. The inventor of the danish patent "Prediction of resonance" (publication number: WO2010118752a1) proposes an algorithm and an apparatus for predicting the resonance of parameters between two related oscillation signals, which transform the two related oscillation signals in time domain and frequency domain, and further design two Prediction mechanisms of frequency identification in frequency domain and phase identification in time domain, respectively, to predict the resonance of parameters. However, the algorithm and the device only relate to the pre-warning of parameter rolling, and are not specially designed on the timeliness of the pre-warning, which is obviously different from the advanced pre-warning emphasized by the invention.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention provides a method, an apparatus, a medium and a device for early warning of parametric resonance motions of an ocean floating structure, which implement advanced early warning of parametric resonance motions by using a more efficient algorithm and less apparatus cost, so as to efficiently avoid the parametric resonance motions by consuming less energy when the initial motion amplitude of the parametric resonance occurs is small.
In order to achieve the above objects and other related objects, the present invention provides a method for pre-warning the parameter resonance motion of a floating structure, comprising: acquiring real-time acquired motion signals of the ocean floating structure on different degrees of freedom; linearly superposing the time history data of the different motion signals to obtain time history data of a combined signal; generating instantaneous frequency time history data of the instantaneous frequency of the combined signal changing along with time according to the time history data of the combined signal; identifying a frequency discontinuity from the instantaneous frequency history data; wherein the frequency discontinuity is caused by a frequency doubling relationship between motion signals in at least two degrees of freedom when parametric resonance motion occurs; and calculating the moment of the occurrence of the parameter resonance motion according to the frequency mutation so as to carry out early warning.
In an embodiment of the present invention, generating the instantaneous frequency time history data of the temporal variation of the instantaneous frequency of the combined signal according to the time history data of the combined signal is implemented based on an incremental real-time hilbert-yellow algorithm, and includes: screening all modal functions which are locally symmetrical to zero of the average value from the combined signal; and performing Hilbert transform on the screened mode functions to obtain the instantaneous frequency.
In an embodiment of the present invention, the calculating the time when the parameter resonance motion occurs according to the frequency jump includes:establishing a condition gamma 1 and a condition gamma2：
Wherein f isMA(t) is the instantaneous frequency, thTime of Gibbs peak point, μ1As a parameter, TS2The frequency dip α represents the frequency versus [0, t ] for the natural period of the target motion signalh]Mean frequency f within the intervalAverage(th) Magnitude of the drop, αcrIs a preset critical frequency descending amplitude;
such that:-f′MA(t)＞ΘPR
wherein, thetaPRA change rate threshold, wherein a value exceeding the threshold indicates that the parameter resonance motion is possible, and a value below the threshold indicates that the frequency change is not caused by the parameter resonance; according to the condition gamma 1 and the condition gamma2Calculating the time t of the occurrence of the parameter resonance motionp＝th+μ1TS2。
In an embodiment of the present invention, the change rate threshold Θ isPRThe method comprises the following steps: and the ratio of the difference between the natural frequency of the target motion signal and the natural frequency of the motion signal forming a frequency multiplication relation with the target motion signal to the transition time, wherein the transition time is the sum of the natural period of the target motion signal and the natural period of the motion signal forming the frequency multiplication relation with the target motion signal.
In one embodiment of the present invention, the method is based on the condition Γ 1 and the condition Γ2Before the moment when the parameter resonance motion occurs is calculated, preprocessing the instantaneous frequency time history data to eliminate data points caused by numerical errors; taking the preprocessed instantaneous frequency history data as the transientTime frequency fMA(t) substituting the condition Γ 1 and the condition Γ2And (6) performing calculation.
In an embodiment of the present invention, the preprocessing is implemented based on a moving average algorithm.
In order to achieve the above objects and other related objects, the present invention provides an early warning device for parameter resonance motion of a floating structure, comprising: the signal acquisition module is used for acquiring motion signals of the ocean floating structure on different degrees of freedom, which are acquired in real time; the signal processing module is used for linearly superposing the time history data of the different motion signals to obtain time history data of a combined signal; generating instantaneous frequency time history data of the instantaneous frequency of the combined signal changing along with time according to the time history data of the combined signal; identifying a frequency discontinuity from the instantaneous frequency history data; wherein the frequency discontinuity is caused by a frequency doubling relationship between motion signals in at least two degrees of freedom when parametric resonance motion occurs; and the resonance early warning module is used for calculating the moment of the occurrence of the parameter resonance motion according to the frequency mutation so as to carry out early warning.
In an embodiment of the present invention, the generating of the instantaneous frequency time history data by the signal processing module according to the time history data of the combined signal is implemented based on an incremental real-time hilbert-yellow algorithm, and includes: screening all modal functions which are locally symmetrical to zero of the average value from the combined signal; and performing Hilbert transform on the screened mode functions to obtain the instantaneous frequency.
In an embodiment of the present invention, the resonance early warning module calculates the time when the parameter resonance motion occurs according to the frequency jump by the following method: establishing a condition gamma 1 and a condition gamma2：
Wherein f isMA(t) is the instantaneous frequency, thIs a guitarTime of the Booth peak point, μ1As a parameter, TS2The frequency dip α represents the frequency versus [0, t ] for the natural period of the target motion signalh]Mean frequency f within the intervalAverage(th) Magnitude of the drop, αcrIs a preset critical frequency descending amplitude;
such that:-f′MA(t)＞ΘPR
wherein, thetaPRA change rate threshold, wherein a value exceeding the threshold indicates that the parameter resonance motion is possible, and a value below the threshold indicates that the frequency change is not caused by the parameter resonance; according to the condition gamma 1 and the condition gamma2Calculating the time t of the occurrence of the parameter resonance motionp＝th+μ1TS2。
In an embodiment of the present invention, the change rate threshold Θ isPRThe method comprises the following steps: and the ratio of the difference between the natural frequency of the target motion signal and the natural frequency of the motion signal forming a frequency multiplication relation with the target motion signal to the transition time, wherein the transition time is the sum of the natural period of the target motion signal and the natural period of the motion signal forming the frequency multiplication relation with the target motion signal.
In an embodiment of the present invention, the apparatus further includes: a data preprocessing module for preprocessing the data according to the condition Γ 1 and the condition Γ2Before the moment when the parameter resonance motion occurs is calculated, preprocessing the instantaneous frequency time history data to eliminate data points caused by numerical errors; taking the preprocessed instantaneous frequency time history data as the instantaneous frequency fMA(t) substituting the condition Γ 1 and the condition Γ2And (6) performing calculation.
In an embodiment of the present invention, the preprocessing is implemented based on a moving average algorithm.
To achieve the above and other related objects, the present invention provides a storage medium, in which a computer program is stored, and the computer program is loaded and executed by a processor to implement the method for warning the parameter resonance motion of the marine floating structure as described above.
To achieve the above and other related objects, the present invention provides an electronic device, comprising: a processor, and a memory; wherein the memory is for storing a computer program; the processor is used for loading and executing the computer program to enable the electronic device to execute the early warning method for the parameter resonance motion of the ocean floating structure.
To achieve the above and other related objects, the present invention provides a system for pre-warning parametric resonance motions of a floating structure, comprising: the angular motion detection device is arranged on the ocean floating structure and used for acquiring motion signals of the ocean floating structure on different degrees of freedom in real time; the electronic device as described above, being communicatively connected to the angular motion detection means.
Compared with the KR100827396B1 patent, the early warning method, the early warning device and the early warning equipment for the parameter resonance motion of the ocean floating structure adopt a more efficient algorithm and less device cost to realize the early warning of the parameter resonance motion; compared with the WO2010118752A1, the method adopts an IR-HHT algorithm to acquire motion time-frequency information so as to perform advanced early warning of parameter resonance motion. In addition, the invention is specially designed on the timeliness of early warning, and can carry out advanced early warning on the parameter resonance motion when the initial motion amplitude of the parameter resonance is smaller, so that the parameter resonance motion can be effectively avoided by consuming little energy.
Drawings
Fig. 1 is a schematic view showing a scene of a parametric resonance motion of an ocean floating structure according to an embodiment of the present invention.
Fig. 2 shows a time history data graph of the pitch motion signal S1 and the roll motion signal S2 in the inventive model experiment.
Fig. 3 is a schematic diagram of an early warning hardware device for parameter resonance motion of the marine floating structure according to an embodiment of the present invention.
Fig. 4 is a schematic diagram illustrating an early warning method for parameter resonance motion of a marine floating structure according to an embodiment of the present invention.
Fig. 5 shows a flow chart of the incremental real-time hilbert-yellow (IR-HHT) algorithm in an embodiment of the invention.
FIG. 6 shows an instantaneous frequency curve f (t) and its moving average fMA(t) and a Rate of Change-10 f'MA(t) schematic representation.
Fig. 7 is a diagram showing a simulation result of the parameter roll advance warning obtained in the model experiment of the present invention.
Fig. 8 is a schematic diagram of an early warning software device for parameter resonance motion of the marine floating structure according to an embodiment of the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The invention provides an advanced early warning algorithm and an advanced early warning device for parameter resonance motion of an ocean floating structure (such as a ship, an ocean platform, an offshore floating fan and the like), which adopt a more efficient algorithm and less device cost to realize advanced early warning of the parameter resonance motion so as to consume less energy to effectively avoid the parameter resonance motion when the initial motion amplitude of the parameter resonance occurs is smaller.
As shown in fig. 1, the marine floating structure 2 is excited by a wave 1 to perform six-degree-of-freedom oscillatory motion, comprising: x surging, y surging, z surging,Roll, theta pitch, psi yaw.
When the parameter resonance motion occurs, the ocean floating structure does wave frequency motion on some degrees of freedom and does low frequency resonance motion on some degrees of freedom, and a frequency doubling relationship exists between the two types of motions with different frequencies, such as: the frequency multiplication relation between the pitching and heaving motions and the rolling motion when the ship generates parameters and the frequency multiplication relation between the heaving and pitching motions when the Spar platform greatly pitches and the like.
The following will illustrate the mechanism of the parameter resonance motion and its frequency multiplication relationship by taking the parameter roll of the ship as an example.
The ship parameter rolling is parameter self-excited vibration caused by nonlinear periodic variation of rolling restoring force in longitudinal waves, and is simplified into a horse break equation in the following form:
wherein,is roll angle, zeta is damping coefficient, omega0And ω represents the roll natural frequency and wave encounter frequency, respectively, ε is the roll restoring force amplitude, and the term ε cos ω t is the periodically varying roll restoring force. When ζ and ε are small, ω is 2 ω0That is, the pitch frequency is about twice the roll natural frequency, and there is an unstable boundary, which is the frequency doubling relationship satisfied when the parametric resonance motion occurs.
Fig. 2 shows the time course curves of the pitch motion signal S1 (see fig. 11) and the roll motion signal S2 (see fig. 10) in the frequency doubling relationship when the parametric resonance motion occurs, which are obtained in the model experiment. As can be seen from fig. 2, between the two dashed vertical lines, signal S2 completes one cycle of oscillatory motion, and signal S1 completes two cycles of oscillatory motion, indicating the formation of a parametric resonance condition. At the same time, the amplitude of the signal S2 increases rapidly, creating a large and violent motion, which poses a great threat to the safety of the marine floating structure.
It can also be seen from fig. 2 that, when the amplitude of the signal S2 is still smaller, the frequency multiplication relationship between S1 and S2 is formed. Therefore, the invention identifies the frequency multiplication relation when the motion amplitude at the initial stage of resonance is small, thereby carrying out early warning of parameter resonance.
Referring to fig. 3, the early warning device for parameter resonance motion of the marine floating structure provided by the invention mainly comprises: motion detection device and the electronic equipment who is connected with motion detection device electricity, wherein, motion detection device is preferred: a six-axis gyroscope 301; the electronic device is a device including a processor (CPU/MCU/SOC), a memory (ROM/RAM), an input/output interface (bus interface/communication interface), and a system bus, and is preferably: a micro-mainframe computer 302. In a practical ship application scenario, the motion detection device and the electronic equipment may be installed in an equipment container box (e.g. 4 in fig. 1) of the ship and communicatively connected to a warning monitor (e.g. 3 in fig. 1) installed in a ship cab.
As shown in fig. 4, in the implementation of the present invention, the floating structure is excited by waves to make an oscillating motion, and the six-axis gyroscope 301 collects in real time the time history of two relative motion signals S1 and S2, where parameter resonance may occur, and transmits the signals to the micro main control computer 302. The micro main control computer 302 is integrated with a parameter resonance motion advance warning algorithm, and the algorithm firstly carries out linear superposition on two signal time histories to obtain a combined signal time history x (t) ═ S1+ S2; then, analyzing the time history x (t) of the synthesized signal based on an Incremental Real-time Hilbert-Huang (IR-HHT) algorithm to obtain an Instantaneous Frequency (IF) containing time frequency information of two motion signals; then, the algorithm analyzes the obtained instantaneous frequency, and the frequency mutation caused by parameter resonance is identified, so that an early warning result is obtained; finally, the early warning result is transmitted to an early warning monitor of the cab through a wireless signal 7. When the early warning signal shows that parameter resonance occurs, corresponding measures can be taken to avoid the parameter resonance movement.
The principle of the method for the pre-warning of the parametric resonance motions of the marine floating structure according to the present invention will be described in detail below.
In the IR-HHT algorithm, it is assumed that any complex signal can be decomposed into a finite number of Intrinsic Mode Functions (IMFs) with some physical significance. To obtain the IMF, the algorithm employs a filtering process called Empirical Mode Decomposition (EMD) to gradually find a series of IMFs of different frequencies from high to low by means of a continuously repeated filtering procedure. In order for IMF to have a certain physical significance, two conditions should be met:
1) the sum of the number of local maxima and minima on the curve must be equal to the number of zeros or differ by at most 1;
2) at any time, the average of the envelope of local maxima and the envelope of local minima is close to zero.
The first condition ensures that the IMF is narrow-band and the second condition ensures that the IMF has no zero-point offset. These two conditions ensure that the IMF is locally symmetric to mean zero, making it similar to a sine-valued function (sinusoid-like), but its period and amplitude are different from the sine-valued function and may vary. The meaningful instantaneous frequency IF can be found by directly using the Hilbert transform on the IMFs of these chord-like functions.
The EMD process in the IR-HHT method is shown in fig. 5, and in particular, for an original signal x (t):
step 1. initialize r0(t)＝x(t),i＝1；
And 2, decomposing the ith IMF, comprising:
A. initial h0(t)＝ri(t),k＝1；
B. Find out h0(t) all local maxima and local minima hk-1(t), if no new extreme value exists, jumping to the step D;
C. respectively connecting local maximum values and local minimum values in series into upper and lower envelope lines by adopting Hermite interpolation;
D. calculating the average of the upper and lower envelope lines to obtain the mean envelope line mk-1(t)；
E.hk(t)＝hk-1(t)-mk-1(t)；
F. Inspection hk(t) whether IMF is satisfied; if so, IMFi(t)＝hk(t), continuing with step 3; if not, returning to the step B and enabling k to be k + 1;
step 3. define ri(t)＝ri-1(t)-IMFi(t)；
Step 4, if ri(t) if there are still at least two maxima, continuing step 2 and making i equal to i + 1; otherwise, r endsi(t) is the average trend component of x (t).
If the IMF can not be solved, the EMD screening process is considered to be completed. Signal x (t) is equal to the superposition of these n IMFs with an average trend:
thus, the signal x (t) is decomposed into n IMFs with frequencies from high to low and a trend function, and Hilbert transform is performed on the IMFs including signals S1 and S2 to obtain the instantaneous frequency IF. Fig. 6 shows the instantaneous frequency IF curve f (t) (see fig. 12) of the sum signal x (t) of the signals S1 and S2 in fig. 2. It can be seen from the graph that the instantaneous frequency IF suddenly changes due to the frequency doubling relationship when the parametric resonance motion occurs, and the IF drops from the frequency of the signal S1 to the frequency of the signal S2 (the frequency of the signal S1 before the sudden change of the frequency is dominant, and the frequency of the signal S2 after the sudden change of the frequency is dominant). The invention designs an advanced early warning algorithm based on the sudden change of the instantaneous frequency IF to forecast the time when the parameter resonance occurs.
First, a Moving Average (Moving Average) method is introduced to preprocess the IF curve f (t) to eliminate sharp points caused by numerical errors in the curve of fig. 6. Instantaneous frequency f obtained by moving averageMA(t) (see 13) and the Change thereof-10 f'MA(t) is plotted as shown in FIG. 6. Thus, based on the instantaneous frequency fMA(t) designing a parameter resonance motion advanced early warning algorithm, wherein the algorithm comprises two conditions: frequency variation condition Γ1And rate of change condition Γ2。
Frequency variation condition Γ1For identifying sudden changes in frequency when parameter resonances occur. According to the gibbs phenomenon (gibbspenomenon), the discontinuity in frequency is reflected as a peak point (hump) in the instantaneous frequency (see 14), as shown in fig. 6. Based on the peak point, the advanced early warning algorithm designs a frequency change condition gamma1：
Wherein, the first isThe line condition takes the maximum point of the instantaneous frequency as the possible Gibbs peak point, thTime of peak point; the second row is used to determine if the interval [0, μ1TS2]Whether the instantaneous frequency is in a falling phase, where mu1Preferably 0.8 to 1, and in the third row, the frequency drop α represents the frequency relative to [0, th]Mean frequency f within the intervalAverage(th) Amplitude of drop, critical frequency drop αcrPreferably around 0.5, which is also the ratio of the frequency of the signal S2 to the frequency of the signal S1 at which parametric resonant motion occurs. Thus, the formula establishes the frequency variation condition Γ by determining the magnitude of the frequency drop after the Gibbs peak point1。
Since sudden changes in the instantaneous frequency may also occur in slow sea state changes, a rate of change condition Γ is introduced2As another criterion. First, a threshold theta of change rate needs to be setPRAbove this threshold, parametric resonance motion is likely to occur, and below the threshold, frequency changes due to parametric resonance are not likely to occur.
When the parameter resonance occurs, the instantaneous frequency of the resultant signal x (t) will be at a certain transition time ttranFrequency f of internal slave signal S1S1Down to frequency f of signal S2S2. Thus, the change rate threshold Θ can be setPR：
Wherein the periods of the signals S1 and S2 satisfy TS1＝TS22; transition time ttranSet to the sum of one S1 cycle and one S2 cycle. Finally, the rate of change condition Γ is set2：
Wherein the threshold of change rateThe value ΘPRIf the setting is too small, the slow change of the instantaneous frequency caused by the change of the sea state can be wrongly predicted, and if the setting is too large, the parameter rolling can not be predicted.
So far, the instantaneous frequency obtained based on the IR-HHT method applies the frequency variation condition Γ1And rate of change condition Γ2The formed advanced early warning algorithm can forecast the parameter rolling at tpThe time is as follows: t is tp＝th+μ1TS2。
The parameter resonance motion advanced early warning algorithm and the device are arranged in a model of a certain container ship to carry out advanced early warning of container ship parameter rolling, the effect of the invention is verified through experiments, and the early warning result is shown in figure 7.
Fig. 7 shows the experimental results of 4 conditions, each including the time history of roll angle 15 and pitch angle 16 acquired by the six-axis gyroscope in the experiment and the instantaneous frequency 17 obtained by the IR-HHT algorithm. In addition, fig. 7 also includes the pitch frequency fθ(see 18) and roll natural frequency froll(see FIG. 19).
As can be seen from fig. 7, when the parameter roll occurs, the roll angle 15 is continuously increased, the instantaneous frequency 17 is suddenly changed from the pitch frequency 18 to the roll natural frequency 19, and the advance warning algorithm warns the moment 20 when the parameter roll occurs. At this time, the amplitude of the parameter roll is also small.
According to experimental results, the parameter resonance motion advanced early warning algorithm and device provided by the invention can forecast when the parameter resonance motion amplitude is small so as to take corresponding evasive measures, and can effectively guarantee the safety of the marine floating structure.
In addition, the present invention includes a storage medium comprising: various media such as ROM, RAM, magnetic disk or optical disk, etc. which can store program codes, wherein the computer program is stored, and when the computer program is loaded and executed by a processor, the computer program realizes all or part of the steps of the method for early warning of the parameter resonance motion of the ocean floating structure in the foregoing embodiments. Since the technical features in the foregoing embodiments can be applied to this embodiment, detailed descriptions thereof are not repeated.
Specifically, as shown in fig. 8, the computer program is implemented based on the following modules:
the signal acquisition module 801 acquires real-time acquired motion signals of the marine floating structure in different degrees of freedom.
The signal processing module 802 first linearly superimposes the time history data of the different motion signals to obtain the time history data of the combined signal. Then, instantaneous frequency time history data of the instantaneous frequency of the combined signal changing with time is generated according to the time history data of the combined signal, such as: analyzing the time history of the combined signal based on an incremental real-time Hilbert-Huang algorithm to obtain the instantaneous frequency of the time-frequency information containing the combined signal, comprising: screening (e.g., based on an empirical mode decomposition algorithm) all mode functions from the combined signal that are locally symmetric to mean zero; and performing Hilbert transform on the screened mode functions to obtain the instantaneous frequency. Subsequently, it is identified from the instantaneous frequency history data that a frequency jump is caused by a frequency doubling relationship between the motion signals in at least two degrees of freedom when a parametric resonance motion occurs.
The resonance early warning module 803 calculates the moment of occurrence of the parameter resonance motion according to the frequency mutation for early warning, for example: preprocessing the curve of the instantaneous frequency (e.g., based on a moving average algorithm) to eliminate error data points; according to the preprocessed instantaneous frequency fMA(t) establishing a condition Γ 1 and a condition Γ2：
Wherein, thTime of Gibbs peak point, μ1As a parameter, the frequency dip α represents the frequency versus [0, th]Interval(s)Mean frequency f of innerAverage(th) Magnitude of the drop, αcrIs a predetermined critical frequency drop.
such that:-f′MA(t)＞ΘPR
Wherein, thetaPRA threshold rate of change, above which a parametric resonance motion is likely to occur, and below which a frequency change not caused by the parametric resonance is indicated. Optionally, the change rate threshold Θ isPRThe method comprises the following steps: the ratio of the difference between the natural frequency of the target motion signal and the natural frequency of the motion signal forming a frequency multiplication relation with the target motion signal to the transition time, wherein the transition time is the sum of the natural period of the target motion signal and the natural period of the motion signal forming the frequency multiplication relation with the target motion signal.
At this time, the time t of the occurrence of the parameter resonance motion is calculatedp＝th+μ1TS2。
So far, the instantaneous frequency obtained based on the IR-HHT method applies the frequency variation condition Γ1And rate of change condition Γ2The formed advanced early warning algorithm can forecast the parameter rolling at tpThe time is as follows: t is tp＝th+μ1TS2。
In summary, the early warning method, device, storage medium and apparatus for detecting the parametric resonance motions of the marine floating structure of the present invention effectively overcome various disadvantages in the prior art, and have high industrial utility value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (15)
1. An early warning method for parameter resonance motion of an ocean floating structure is characterized by comprising the following steps:
acquiring real-time acquired motion signals of the ocean floating structure on different degrees of freedom;
linearly superposing the time history data of the different motion signals to obtain time history data of a combined signal;
generating instantaneous frequency time history data of the instantaneous frequency of the combined signal changing along with time according to the time history data of the combined signal;
identifying a frequency discontinuity from the instantaneous frequency history data; wherein the frequency discontinuity is caused by a frequency doubling relationship between motion signals in at least two degrees of freedom when parametric resonance motion occurs;
and calculating the moment of the occurrence of the parameter resonance motion according to the frequency mutation so as to carry out early warning.
2. The method of claim 1, wherein generating the instantaneous frequency epoch data from the epoch data of the combined signal is based on an incremental real-time hilbert-yellow algorithm.
3. The method of claim 1, wherein calculating the time when the parameter resonance motion occurs according to the frequency mutation comprises:
establishing a condition gamma 1 and a condition gamma2：
Γ1：
Wherein f isMA(t) is the instantaneous frequency, thTime of Gibbs peak point, μ1As a parameter, TS2The frequency dip α represents the frequency versus [0, t ] for the natural period of the target motion signalh]Mean frequency f within the intervalAverage(th) Magnitude of the drop, αcrIs a preset critical frequency descending amplitude;
Γ2：
wherein, thetaPRA change rate threshold, wherein a value exceeding the threshold indicates that the parameter resonance motion is possible, and a value below the threshold indicates that the frequency change is not caused by the parameter resonance;
according to the condition gamma 1 and the condition gamma2Calculating the time t of the occurrence of the parameter resonance motionp＝th+μ1TS2。
4. The method according to claim 3, characterized in that said threshold rate of change ΘPRThe method comprises the following steps: and the ratio of the difference between the natural frequency of the target motion signal and the natural frequency of the motion signal forming a frequency multiplication relation with the target motion signal to the transition time, wherein the transition time is the sum of the natural period of the target motion signal and the natural period of the motion signal forming the frequency multiplication relation with the target motion signal.
5. Method according to claim 3, characterized in that said method is based on said condition Γ 1 and said condition Γ2Before the moment when the parameter resonance motion occurs is calculated, the method further comprises the following steps:
preprocessing the instantaneous frequency time history data to eliminate data points therein caused by numerical errors;
taking the preprocessed instantaneous frequency time history data as the instantaneous frequency fMA(t) substituting the condition Γ 1 and the condition Γ2And (6) performing calculation.
6. The method of claim 5, wherein the preprocessing is performed based on a moving average algorithm.
7. An early warning device for parameter resonance movement of an ocean floating structure is characterized by comprising:
the signal acquisition module is used for acquiring motion signals of the ocean floating structure on different degrees of freedom, which are acquired in real time;
the signal processing module is used for linearly superposing the time history data of the different motion signals to obtain time history data of a combined signal; generating instantaneous frequency time history data of the instantaneous frequency of the combined signal changing along with time according to the time history data of the combined signal; identifying a frequency discontinuity from the instantaneous frequency history data; wherein the frequency discontinuity is caused by a frequency doubling relationship between motion signals in at least two degrees of freedom when parametric resonance motion occurs;
and the resonance early warning module is used for calculating the moment of the occurrence of the parameter resonance motion according to the frequency mutation so as to carry out early warning.
8. The apparatus of claim 7, wherein the signal processing module generates the instantaneous frequency time history data from the time history data of the combined signal based on an incremental real-time Hilbert-Huang algorithm.
9. The device of claim 7, wherein the resonance early warning module calculates the occurrence time of the parameter resonance motion according to the frequency mutation by:
establishing a condition gamma 1 and a condition gamma2：
Γ1：
Wherein f isMA(t) is the instantaneous frequency, thTime of Gibbs peak point, μ1As a parameter, TS2The frequency dip α represents the frequency versus [0, t ] for the natural period of the target motion signalh]Mean frequency f within the intervalAverage(th) Magnitude of the drop, αcrIs a preset critical frequency descending amplitude;
Γ2：
wherein, thetaPRA change rate threshold, wherein a value exceeding the threshold indicates that the parameter resonance motion is possible, and a value below the threshold indicates that the frequency change is not caused by the parameter resonance;
according to the condition gamma 1 and the condition gamma2Calculating the time t of the occurrence of the parameter resonance motionp＝th+μ1TS2。
10. The apparatus according to claim 9, wherein said threshold rate of change ΘPRThe method comprises the following steps: and the ratio of the difference between the natural frequency of the target motion signal and the natural frequency of the motion signal forming a frequency multiplication relation with the target motion signal to the transition time, wherein the transition time is the sum of the natural period of the target motion signal and the natural period of the motion signal forming the frequency multiplication relation with the target motion signal.
11. The apparatus of claim 9, further comprising: the data preprocessing module is used for preprocessing the instantaneous frequency time history data to eliminate data points caused by numerical errors before the moment when the resonance early warning module calculates the parameter resonance motion; taking the preprocessed instantaneous frequency time history data as the instantaneous frequency fMA(t) substituting the condition Γ 1 and the condition Γ2And (6) performing calculation.
12. The apparatus of claim 11, wherein the preprocessing is performed based on a moving average algorithm.
13. A storage medium having a computer program stored thereon, wherein the computer program when loaded and executed by a processor implements the method for warning of parametric resonance motions of a marine floating structure as claimed in any one of claims 1 to 6.
14. An electronic device, comprising: a processor, and a memory; wherein,
the memory is used for storing a computer program;
the processor is used for loading and executing the computer program to enable the electronic device to execute the early warning method for the parameter resonance motion of the ocean floating structure according to any one of claims 1 to 6.
15. An early warning system for parameter resonance motions of an ocean floating structure, comprising:
the angular motion detection device is arranged on the ocean floating structure and used for acquiring motion signals of the ocean floating structure on different degrees of freedom in real time;
the electronic device of claim 14, communicatively coupled to the angular motion detection apparatus.
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| JP2020524635A (en) | 2020-08-20 |
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