CN110186384B - Ship structure stress monitoring system sensor deviation fault diagnosis method - Google Patents
Ship structure stress monitoring system sensor deviation fault diagnosis method Download PDFInfo
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- CN110186384B CN110186384B CN201910552343.1A CN201910552343A CN110186384B CN 110186384 B CN110186384 B CN 110186384B CN 201910552343 A CN201910552343 A CN 201910552343A CN 110186384 B CN110186384 B CN 110186384B
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- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
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Abstract
The invention belongs to the field of ship structure stress monitoring, and particularly relates to a method for diagnosing deviation faults of a sensor of a ship structure stress monitoring system. The invention collects the stress real-time data in a certain period of time by the fiber grating strain sensor arranged at the structure monitoring point, searches the historical stress data of the fiber grating strain sensor with the same or close to the ship motion amplitude in the database, and can judge whether the corresponding fiber grating strain has the deviation fault or not by combining the judgment condition of the deviation fault of the sensor. The invention is easy to realize, has high operability and reliability, does not generate misjudgment, can accurately judge whether the strain of the fiber bragg grating generates deviation fault in real time, and can guide personnel to check and maintain the sensor generating the deviation fault in time, thereby ensuring the normal operation of the ship structure stress monitoring system.
Description
Technical Field
The invention belongs to the field of ship structure stress monitoring, and particularly relates to a method for diagnosing deviation faults of a sensor of a ship structure stress monitoring system.
Background
The structural strength of the ship body is one of main factors influencing the safety of the ship, various specifications and criterions are set in the design and construction process of the ship in order to ensure that the ship body has enough strength to resist the damage effect of environmental loads on the structure, but for the ship sailing in the marine environment, the load borne by the structure has strong randomness, and the random factors cannot be accurately forecasted in the design and construction process, so that a stress monitoring system of the ship body structure is introduced to ensure the safety of the ship in the use process.
The ship structure stress monitoring system is an important component of an intelligent ship, and the sensor is used as an important element of a ship structure stress monitoring technology, so that the effectiveness and the reliability of the whole system are determined by whether the sensor can work normally or not. The fiber bragg grating strain sensor has the advantages of large measuring range, no need of a temperature compensation sensor, capability of avoiding external influences such as electromagnetic interference and the like, and can ensure the accuracy of monitoring data; thus, hull structure stress monitoring systems employ this type of sensor. However, due to the complicated and bad working environment of the sensor and the special installation position, the sensor becomes the most prone to failure in the system. Among them, the most common faults of the sensor are deviation faults caused by the weakening of the light source intensity of the sensor or the occurrence of cold joint between the sensor and the base, between the base and the structure, between the light paths and other structures. If the sensor has a deviation fault, the main signal characteristic is that the stress data measured by the sensor has a certain difference compared with the normal data, but the difference cannot be simply used as a fault judgment condition. Therefore, in order to accurately judge whether the sensor has a deviation fault, a special diagnostic algorithm for the sensor deviation fault needs to be designed, the algorithm can accurately diagnose the deviation fault of the sensor in real time, and the deviation fault information of the sensor can be timely fed back to ship operation and equipment maintenance personnel.
Disclosure of Invention
The invention aims to provide a method for diagnosing the deviation fault of a sensor of a ship structure stress monitoring system, which can accurately diagnose the deviation fault of the sensor.
The purpose of the invention is realized by the following technical scheme:
a method for diagnosing deviation faults of a sensor of a ship hull structure stress monitoring system comprises the following steps:
step 1: the fiber bragg grating strain sensor collects strain signals of a hull structure within a period of time;
step 2: processing the strain signal to obtain stress data;
and step 3: calculating the sample mean value of the stress data measured by the fiber grating strain sensor in the current time period
Mean amplitude of stress
And average across zero cycles
And 4, step 4: searching the average amplitude of the stress data measured by the fiber bragg grating strain sensor in a certain historical time period when the difference between the average amplitude of the ship motion in the current time period and the average amplitude of the stress data measured by the fiber bragg grating strain sensor in the current time period is less than 5 percent from the database
And average across zero cycles
Judging whether the stress data measured by the fiber bragg grating strain sensor in the current time period meets the following conditions:
a,
II,
III,
Wherein σsThe yield limit of the steel material measured by the fiber grating strain sensor; k ranges from 0.75 to 0.80; m is1The value range is 0.8 to 0.9, m2The value range is 1.1 to 1.2;
and 5: and if the stress data measured by the fiber grating strain sensor in the current time period simultaneously meet the three conditions in the step 4, diagnosing that the fiber grating strain sensor has deviation faults.
The present invention may further comprise:
the specific method for processing the strain signal in the step 2 comprises the following steps:
step 2.1: the fiber bragg grating strain sensor converts the collected strain signal into a wavelength signal;
step 2.2: transmitting the wavelength signal to a demodulator to be converted into an electric signal;
step 2.3: transmitting the electric signal to a strain signal processing program and converting the electric signal into stress data;
step 2.4: and carrying out sampling frequency filtering on the stress data to remove high-frequency noise components mixed in the data.
The invention has the beneficial effects that:
the invention collects the stress real-time data in a certain period of time by the fiber grating strain sensor arranged at the structure monitoring point, searches the historical stress data of the fiber grating strain sensor with the same or close to the ship motion amplitude in the database, and can judge whether the corresponding fiber grating strain has the deviation fault or not by combining the judgment condition of the deviation fault of the sensor. The invention is easy to realize, has high operability and reliability, does not generate misjudgment, can accurately judge whether the strain of the fiber bragg grating generates deviation fault in real time, and can guide personnel to check and maintain the sensor generating the deviation fault in time, thereby ensuring the normal operation of the ship structure stress monitoring system.
Drawings
FIG. 1 is a flow chart of the present invention.
FIG. 2 is a graph of data characteristics of a fiber grating strain sensor in the event of a bias fault.
Fig. 3 is a functional block diagram of a hull structure stress monitoring system.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The ship structure stress monitoring system comprehensively utilizes a structure parameter identification technology, an optical fiber sensing technology, a database technology, a multi-data information fusion technology, an ultra-large information quantity data processing technology, a ship structure finite element analysis technology, an intensity evaluation theory, related sensors, software and hardware equipment and the like to realize real-time monitoring and evaluation of the safety of a ship structure, and the system mainly has the main functions of data acquisition, environment monitoring, stress monitoring, data processing, intensity evaluation, alarming and recording, a database, an interactive interface and the like, so that the safety performance of a sailing ship is improved, and data are accumulated for the design of the ship structure. The main functions of the system are shown in figure 3.
The ship structure stress monitoring system is an important component of an intelligent ship, and the sensor is used as an important element of a ship structure stress monitoring technology, so that the effectiveness and the reliability of the whole system are determined by whether the sensor can work normally or not. The fiber bragg grating strain sensor has the advantages of large measuring range, no need of a temperature compensation sensor, capability of avoiding external influences such as electromagnetic interference and the like, and can ensure the accuracy of monitoring data; thus, hull structure stress monitoring systems employ this type of sensor. However, due to the complicated and bad working environment of the sensor and the special installation position, the sensor becomes the most prone to failure in the system.
The stress in the hull structure stress monitoring system is collected by using a fiber bragg grating strain sensor. The signal transmission process is as follows: the optical fiber sensor converts a strain signal of the ship structure into a wavelength signal, transmits the wavelength signal to the signal demodulator through an optical cable, converts the wavelength signal into an electric signal by the demodulator, uploads the electric signal to the strain signal processing program, and then the strain signal processing program identifies the signal, converts the signal into a stress signal and stores the stress signal in the database system. The calculation formula of the strain converted into stress is shown in table 1, which is specifically determined by the arrangement form of the sensors.
The invention aims to provide a method for diagnosing the deviation fault of a sensor of a ship hull structure stress monitoring system, which aims to solve the problem of accurately diagnosing the fault of the sensor in the existing ship hull structure stress monitoring system.
The principle of the invention is as follows:
possible causes of sensor deviation failure are possible failure due to sensor mounting, weak light source intensity, and the like. When the sensor has deviation fault, the signal characteristics mainly include that the intensity of the light source is weakened or the sensor and the base, the base and the structure, the optical path and other structures are in cold joint, and the like, which causes the problem that the measured data of the sensor is reduced compared with the normal data. If the sensor has a deviation fault, the main signal characteristic is that the stress data measured by the sensor has a certain difference compared with the normal data, and the characteristic curve is shown in fig. 2, but the condition for judging the fault cannot be simply taken as the characteristic curve. In fact, if the mean value of the sample of the test data in a certain period of time of the sensor is zero, the amplitude of the data measured by the sensor in the certain period of time is smaller than the normal data in a certain historical time which is the same as or close to the ship motion, and the average zero crossing period of the test data in the certain period of time is consistent with the normal data in the certain historical time which is the same as or close to the ship motion amplitude, the deviation fault of the sensor can be basically determined.
TABLE 1
The specific scheme of the invention is as follows:
in order to realize the real-time effective diagnosis of the deviation fault of the sensor of the ship structure stress monitoring system, the invention determines the judgment condition of the deviation fault of the sensor according to the characteristics of data signals when the sensor generates the deviation fault. The invention can accurately judge the working state of the sensor in real time, can accurately judge the sensor with deviation fault, and can give timely feedback to equipment operation or maintenance personnel.
Acquiring a strain signal within a certain period of time by a fiber bragg grating strain sensor arranged at a structure monitoring position, and processing the strain signal and strain processing by a demodulator of a ship structure stress monitoring system; then filtering with sampling frequency to remove high-frequency noise component mixed in data; and finally, identifying the sensor with the fault by combining the normal historical data stored in the database and the judgment condition of the deviation fault of the sensor, and displaying the fault information of the sensor. The specific flow is shown in fig. 1, and the specific method is as follows:
1. low-pass filtering collected data, setting stop band cut-off frequency as sampling frequency, and removing high-frequency noise;
2. calculating the sample mean, zero crossing period and amplitude of the stress time history signal in the past 60 seconds (5-10 periods);
3. calculating an average zero crossing period and an average stress amplitude;
4. if a certain sensor has deviation fault, the measured data of the sensor needs to satisfy the following conditions at the same time:
1) the mean value of the stress data samples of the sensor is zero, in the invention, the upper limit of the range of the zero value is defined as 5 percent of the yield limit of the steel material, namely the mean value of the samples of the stress data measured by the fiber grating strain sensor in the current time period
Is less than the yield limit sigma of the steel material measured by the fiber grating strain sensors5% of the total.
If { X1,X2,…,XnIs the total sample of the stress measurements, then the sample mean
Satisfies the following conditions:
wherein: n is the total number of samples in the period of time, sigmasIs the yield limit of steel materials.
2) The amplitude of the data measured by the sensor in the time period is smaller than the amplitude of the test data in a certain historical time period which is the same as or close to the ship motion amplitude; the amplitude of the data measured by the sensor in the time period is smaller than the amplitude of the test data in a certain historical time period which is the same as or close to the ship motion amplitude, and a specific range of 'smaller than' is given by adopting a coefficient discrimination method. In the invention, the upper limit of the stress average amplitude is 0.75-0.80 of the historical stress average amplitude. The amplitude is the same as or close to the ship motion amplitude, and a specific amplitude range of 'close' needs to be given. For the average value of the ship motion amplitude, when the current value is different from the historical value by less than 5%, the current value is considered to be similar. I.e. the average amplitude of the stress data measured by the fiber grating strain sensor in the current time period
Less than the average amplitude of the stress data measured by the fiber grating strain sensor in a certain historical time period when the difference between the average amplitude of the ship motion in the current time period and the average value of the amplitude of the ship motion in the current time period is less than 5 percent
75% to 80%.
Wherein:
in order to obtain the average magnitude of the stress,
the average amplitude of the historical stress is obtained, m is the number of zero crossing cycles of the stress signal in the time period, and the value of k is 0.75-0.80.
3) The average zero crossing period is consistent with the measured data in a certain historical time period which is the same as or close to the motion amplitude of the ship. The average period of stress, which is generated by the wave-induced bending moment, spans zero. The average zero crossing period is consistent with the measured data in a certain historical time period which is the same as or close to the ship motion amplitude, a coefficient discrimination method is adopted, and a consistent range is given specifically. In the invention, the value of the stress average zero crossing period is between m of the historical stress average zero crossing period1～m2Wherein m is1The value is 0.8-0.9 m2The value is 1.1-1.2. The amplitude is the same as or close to the ship motion amplitude, and a specific amplitude range of 'close' needs to be given. For the average value of the ship motion amplitude, when the current value is different from the historical value by less than 5%, the current value is considered to be similar. Namely the average zero crossing period of the stress data measured by the fiber grating strain sensor in the current time period
And the average zero crossing period of the stress data measured by the fiber grating strain sensor in a certain historical time period when the difference between the average value of the ship motion amplitude in the current time period and the average value of the ship motion amplitude in the current time period is less than 5 percent
The ratio of (A) to (B) satisfies:
wherein:
respectively the current and historical stress average zero crossing periods; m is1The value is 0.8-0.9 m2The value is 1.1-1.2.
And further limiting, the statistics of the data amplitude adopts a method of analyzing an extreme value of the monitoring data of the sensor in a zero crossing period, and the corresponding amplitude is obtained by calculation.
The determination of the zero crossing period of the data adopts the condition that the value of the data is changed from a negative value to a positive value.
The statistics of the ship motion historical data (including amplitude and average zero crossing period) adopts the following method: firstly, recording the first-appearing ship motion as historical data; if at some future time the same vessel motion occurs again, the database is updated. The ship motion amplitude is the same or close, and a certain range exists for the regulation that the amplitude is close. For the average value of the ship motion amplitude, when the current value is different from the historical value by less than 5%, the current value is considered to be similar. If the condition cannot be met, the current working condition can be considered as a new working condition and is stored in a database to be used as a reference or comparison value of the future sea state.
The ship motion amplitude is the same or close, and a certain range exists for the regulation that the amplitude is close. For the average value of the ship motion amplitude, when the current value is different from the historical value by less than 5%, the current value is considered to be similar. If the condition cannot be met, the current working condition can be considered as a new working condition and is stored in a database to be used as a reference or comparison value of the future sea state.
Counting real-time data acquired by a sensor within a certain period of time, analyzing extreme values of the sensor within each zero crossing period, and calculating corresponding amplitude values; counting the sample mean value of the real-time data in the period of time; searching a historical stress amplitude of the sensor which is the same as or close to the ship motion amplitude in a database; searching an average zero crossing period of historical stress of the sensor, which is the same as or close to the ship motion amplitude, in a database; and judging whether the corresponding sensor has deviation faults or not by combining the judgment conditions of the deviation faults of the sensors.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A method for diagnosing deviation faults of a sensor of a ship hull structure stress monitoring system is characterized by comprising the following steps:
step 1: the fiber bragg grating strain sensor collects strain signals of a hull structure within a period of time;
step 2: processing the strain signal to obtain stress data;
and step 3: calculating the sample mean value of the stress data measured by the fiber grating strain sensor in the current time period
Mean amplitude of stress
And average across zero cycles
And 4, step 4: searching the average amplitude of the stress data measured by the fiber bragg grating strain sensor in a certain historical time period when the difference between the average amplitude of the ship motion in the current time period and the average amplitude of the stress data measured by the fiber bragg grating strain sensor in the current time period is less than 5 percent from the database
And average across zero cycles
Judging whether the stress data measured by the fiber bragg grating strain sensor in the current time period meets the following conditions:
a,
II,
III,
Wherein σsThe yield limit of the steel material measured by the fiber grating strain sensor; k ranges from 0.75 to 0.80; m is1The value range is 0.8 to 0.9, m2The value range is 1.1 to 1.2;
and 5: and if the stress data measured by the fiber grating strain sensor in the current time period simultaneously meet the three conditions in the step 4, diagnosing that the fiber grating strain sensor has deviation faults.
2. The method for diagnosing the deviation fault of the sensor of the ship hull structure stress monitoring system according to claim 1, wherein the method comprises the following steps: the specific method for processing the strain signal in the step 2 is as follows:
step 2.1: the fiber bragg grating strain sensor converts the collected strain signal into a wavelength signal;
step 2.2: transmitting the wavelength signal to a demodulator to be converted into an electric signal;
step 2.3: transmitting the electric signal to a strain signal processing program and converting the electric signal into stress data;
step 2.4: and carrying out sampling frequency filtering on the stress data to remove high-frequency noise components mixed in the data.
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| CN112965014B (en) * | 2021-03-04 | 2022-09-02 | 哈尔滨工业大学 | Compensation method and device for magnetic interference caused by change of mechanical structure of airplane |
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