CN109870284B - Damping test method for FAST telescope cabin cable system - Google Patents
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Abstract
The invention discloses a damping test method of a FAST telescope cabin cable system, which is characterized by comprising the following steps: and applying excitation to enable the cabin cable system to generate free damping vibration, and calculating the damping and natural vibration frequency of the cabin cable system by measuring the vibration acceleration of the cabin. The invention can measure and evaluate the vibration response level of the cabin-substitute +6 cable system in the real environment on the FAST telescope engineering site, and provides the real damping ratio parameters of the system for the control programs of cable drive debugging, cabin cable joint debugging and telescope joint debugging according to the damping ratio of the vibration response test cabin cable system, thereby ensuring the control precision of the FAST telescope.
Description
The technical field is as follows:
the invention relates to the technical field of cabin cable damping system testing, in particular to a damping testing method of a FAST telescope cabin cable system.
Background art:
the project of a Spherical radio Telescope (Five-rounded-meter-Aperture-Spherical-radio-Telescope) with the caliber of 500 meters is called FAST for short. The project is built in a large pit and a large pit, a keeper, a spherical radio telescope with the caliber of 500 meters and the opening angle of 120 degrees is built in a natural karst place of the large pit and the keeper in the Kingkocun of the Kingtown, the Pingcang, the Guizhou, the Buyi nationality of the Miao nationality of the Guizhou province.
FAST is composed of a plurality of systems, such as site survey and excavation, an active reflecting surface, feed source support, measurement and control, a receiver and a terminal, and observation base construction. The feed source supporting system is one of three independent innovations of FAST, and comprises the following components: the device comprises a support tower, a cable drive, a feed source cabin, a cabin parking platform, dynamic monitoring and lightning protection. 6 hundred-meter high towers uniformly distributed on the circumference with the diameter of 600 meters support 6 steel cables to drag a feed source cabin weighing about 30 tons, the feed source cabin moves in a range of 200 meters at 150 meters high altitude, and meanwhile, an AB shaft mechanism and a stewart platform in the cabin finely adjust a receiver, the real-time positioning precision of a feed source is required to be better than 10 millimeters, so that the high-precision pointing tracking observation of a telescope on a celestial body is realized.
And the damping is an important factor influencing the control accuracy of the FAST feed source support system. The accurate positioning of the feed source supporting system to the receiver of the lower platform in the cabin is realized through joint debugging control of three-level adjusting mechanisms, firstly, the cable driving system primarily adjusts the position and the attitude of the feed source cabin (the error is not larger than 48mm), then, the AB shaft rotating mechanism in the cabin further compensates and adjusts the attitude angle of the lower platform, and finally, the Stewart fine adjusting platform in the cabin compensates the residual positioning error of the lower platform in real time to ensure that the residual positioning error is smaller than RMS (root mean square) 10 mm. The adjustment of the AB axis mechanism is quasi-static, but the dynamic adjustment of the Stewart platform can generate extra reaction force to the feed source cabin, and the reaction force can excite the cabin +6 cable system to generate resonance due to the large flexibility of the cabin +6 cable system, so that the control instability is caused. Only if the cabin cable system has a certain amount of damping, so that the excitation energy is quickly attenuated, the control stability of the system can be ensured, and the required control precision is reached.
To understand the damping of the cabin cable system, the damping ratio of the cabin cable system of various FAST scaling models has been tested. According to the test result, the lower limit of the damping ratio of the various model cabin cable systems is about 0.22%. According to the damping ratio measured by the test, the end-to-end simulation of the FAST feed support system prototype developed by the medium and high performance corporation in 2007 adopts the damping ratio parameter with the minimum value of 0.22%. Simulation results prove that under the damping parameters, the control accuracy of the lower platform in the feed source cabin meets the design requirements, but is in a critical state. Because factors influencing the system damping are complex and changeable, the requirements of a model similarity law are difficult to meet, and the damping ratio parameters obtained according to a model test are difficult to be suitable for the damping ratio of a prototype.
Moreover, the cabin cable damping system has uniqueness: the device is applied to the field environment in the mountainous area, has large span and complex operation condition, and the path of signal transmission to a control room is about 3 kilometers.
At present, no method capable of accurately calculating the damping of the cabin cable damping system exists theoretically, the damping ratio parameter of a cabin cable system prototype can only be obtained through a damping test of the cabin cable system prototype, the damping analysis can only be carried out through an experimental method and is identified from a structural vibration response signal, the obtained damping ratio parameter is inaccurate, and the control accuracy of an FAST telescope cannot be guaranteed.
Disclosure of Invention
In order to solve the problems, the invention provides a damping test method of a FAST telescope cabin cable system, which fills the gap of the damping test of the cabin cable damping system in the technology, can measure and evaluate the vibration response level of a cabin-substitute +6 cable system in the real environment in the FAST telescope engineering field, and tests the real damping ratio of the cabin cable system according to the vibration response.
The invention provides a damping test method of a FAST telescope cabin cable system, which comprises the following steps: the excitation is applied to enable the cabin cable system to generate free damping vibration, and the damping and natural vibration frequency of the cabin cable system are inversely calculated by measuring the vibration acceleration of the cabin.
The method for generating free damping vibration of the cabin cable system comprises the following steps:
(1) operating a cable driving control system of the cabin cable system to enable the cabin to leave the port, operating to a preset position and adjusting to a specified posture, and then locking the winch to enable the cabin to be in an air hovering state; the preset position is any one point on an arc with the selected cabin-replacing space coordinate as the center of a circle and the radius of 0.8-1.4 meters;
(2) the cable driving control system is used for driving the cabin replacement to move to a specified cabin replacement position coordinate at the speed of 100mm/s, then braking is carried out, the cabin replacement is locked tightly again, and the cabin cable system is in a free damping vibration state under the action of motion inertia and generates obvious vibration acceleration and vibration displacement.
The invention further discloses a damping test method of a FAST telescope cabin cable system, which specifically comprises the following steps:
step 7, completing test data recording in the control room, and operating a cable drive control system to enable the cabin to enter the harbor;
and 8, reversely calculating the damping and the natural vibration frequency of the cabin cable system at the cabin-replacing position point according to the measured cabin-replacing vibration response data, thereby obtaining the cabin cable system damping by using an ITD time domain identification method.
Further, after the signals are collected in the step 6, the network port signals and the serial port signals are converted into optical fiber signals through photoelectric conversion and transmitted to a control room; and 7, in the control room, converting all signals into network port signals or serial port signals again through a photoelectric converter for processing.
Further, the step 8 is to analyze and process the collected signals:
the vibration amplitude of a cabin cable system under environmental excitation is evaluated through recording the cabin-replacing wind speed, and is compared with the vibration amplitude generated by artificial excitation in a damping test, so that the vibration signal acquired by an acceleration sensor is determined; and performing FFT (fast Fourier transform) on the vibration signals acquired by the acceleration sensor, and then performing band-pass filtering processing on the vibration signals, and calculating the natural frequency and the damping ratio of the cabin cable.
Has the advantages that: the invention can measure and evaluate the vibration response level of the cabin-substitute +6 cable system in the real environment on the site of the FAST telescope engineering, and provides the real damping ratio parameters of the system for the control programs of cable drive debugging, cabin cable joint debugging and telescope joint debugging according to the damping ratio of the vibration response test cabin cable system, thereby ensuring the control precision of the FAST telescope.
By constructing a set of online data acquisition system, the invention can complete data acquisition of a designated point all day long without being limited by external conditions; and the method of optical fiber transmission is adopted, the attenuation of signals is reduced, and the long-distance transmission of the signals is realized; the selected instrument has good stability, can ensure the continuity of the test and is suitable for the cabin cable damping system.
Figure illustrates the drawings
FIG. 1 is a schematic diagram of a typical cabin replacement location point selected in a damping test of a cabin cable system according to the present invention;
FIG. 2 is a schematic view of a wind speed and direction curve of the cabin-replacing device of the present invention;
FIG. 3 is a schematic view of an acceleration curve of the cabin under environmental excitation according to the present invention;
FIG. 4 is an acceleration curve and a frequency spectrum diagram of the surrogate cabin under the WP1 position free damping vibration state of the invention;
FIG. 5 is a flow chart of the damping test method of the FAST telescope capsule cable system of the present invention.
Wherein, FIGS. 4A and a are low pass filtered curves and identified natural frequencies and damping ratios for a break from X with cabin speed reduced from 100mm/s to 0; FIGS. 4B and B are low pass filtered curves and identified natural frequencies and damping ratios for a commanded stopping in the Z direction with cabin speed reduced from 100mm/s to 0.
Detailed Description
The technical terms involved in the invention are explained as follows:
FAST: a500-meter Aperture Spherical radio Telescope.
Cabin replacement: distinguished from the feed bay. When the FAST feed source cabin is not completed, a temporary cabin similar to a formal cabin in appearance, mass and gravity center is designed to verify the stability of the cable-driven algorithm.
Cabin cable system: the feed source cabin and the cable driving mechanism of the FAS telescope are connected through the anchoring head, are responsible for finishing the attitude adjustment and motion tracking of the feed source cabin in the air, and are important components of the FAST telescope.
On the basis of a measuring instrument, the damping of the cabin cable system is identified by using an ITD time domain identification method. The ITD method is essentially a process of solving the true value, takes an impulse response function as a basis, utilizes the free response of each measuring point measured at the same time to establish a free response data matrix, and establishes a mathematical model of the characteristic matrix by the complex exponential relationship between the response and the characteristic value. And according to the relation between the model characteristic value and the vibration system characteristic value, the characteristic value and the characteristic vector of the system are obtained, and the modal frequency and the damping ratio of the system are included in the characteristic value. The ITD method can use the measuring point signals with the number less than that of excited modes to identify complete modal parameters, and the characteristic enables the time domain identification method to be suitable for parameter identification of complex structures with multiple degrees of freedom, so that the test equipment is minimum, and the test is simple and convenient.
The calculation method is as follows: assuming a multiple degree of freedom system with general viscous damping, the free damping response due to the initial conditions can be expressed as follows (taking the acceleration response as an example)
Wherein 2N is the complex mode number of the system, { ψiAnd
for the ith pair of conjugate complex mode shape vectors of the system,
for initial acceleration at psiiThe coordinate component on, Si、Si *For the ith pair of conjugate feature roots of the system feature equation,
the measurement instants are postponed by Δ t, so that a matrix is obtained
A series of linear matrix transformations are performed by the above two equations and the [ ∑ ] is eliminated, yielding:
the above two equations are equivalent to the problem of solving the matrix eigenvalues, and in consideration of the existence of measurement errors, the above two equations can be replaced by a double least square method to solve the following eigenvalue problem:
the equation can be directly processed and solved to obtain the system vibration mode vector { psir}. Let the eigenvalue of the equation be λr＝ar+jbrThen, there are:
according to the principle that the complex number imaginary parts and the complex number real parts are respectively equal, the following can be obtained:
the natural frequency and damping ratio of the system can be obtained by the formula.
Due to the existence of noise, an error usually exists between the calculated eigenvalue and the eigenvector, so that the calculated eigenvalue and the true eigenvalue lambda'r＝ar′+jbr' the relationship isr＝(1+ε)λ′r. It can be seen that the calculation of the modal frequency by the formula a-8 is determined by the ratio, the calculation result is very accurate, the calculation of the damping coefficient is determined by the absolute value, when Δ t is small, a large error often occurs, and the calculated damping ratio is very inaccurate.
Since the ITD method can calculate the vibration pattern of the recognition system, the recognition result of the vibration pattern can be usedThe damping ratio is further calculated, and the identification precision is improved. Selecting any one row r from the identified vibration mode matrix, wherein the corresponding characteristic value of the row r is arIdentification frequency of ωr. From [ psi]It can be seen that the ratio of adjacent elements in each column is
Namely, it is
Wherein psisrFor the identified row of the characteristic vector, row r, column s, the corresponding characteristic value λ can be calculated by the formula A-9rThereby obtaining the accurate arAnd br。
Calculated eigenvector psirAnd the theoretical mode matrix [ psi }]The corresponding columns in (a) are also in error, assuming a difference of one coefficient. Similar to the case of calculating modal frequency by using the feature values, what actually participates in the calculation is actually the ratio of two adjacent elements in the same column, so that this error is not brought into the calculation of the damping factor, so that the true damping ratio of the system can be obtained by using the feature vectors.
The preparation work to be completed by the present invention includes: and (3) referring to a cabin-replacing and cable-driven design drawing, determining an installation interface, an installation position and an installation direction of the accelerometer in the cabin-replacing, finishing a processing design drawing of the installation interface (including rain-proof), and processing and installing. And an accelerometer is arranged on the substitute cabin, so that debugging and calibration of a measurement system and transmission and acquisition of measurement data are performed. Following the cable driving debugging progress, carrying out cabin-replacing vibration response measurement and related data recording on the machine selection under different cabin positions and postures; and identifying the damping of the cabin cable system by using an ITD time domain identification method.
The test method selects appropriate cabin-replacing position points (four representative position points are selected in an experiment) on the focal plane of the FAST, and the control cable driving equipment drives the cabin-replacing position points to move to the position points. Then 6 winches are locked, free damping vibration is generated by the cabin cable system through excitation, and the damping and natural vibration frequency of the cabin cable system at the cabin replacing position point are calculated back through measuring the vibration acceleration of the cabin replacing.
The invention mainly comprises a data acquisition module, a data transmission module and a data analysis module. The data acquisition means that all sensors finish correct data acquisition in one experiment; the data transmission is to transmit all the collected data to a control room; and the data analysis is based on data acquisition, and the signals are filtered through certain time domain, frequency domain and other changes to obtain the final experimental result.
As shown in FIG. 1, the steps of the overall test method of the present invention are as follows: firstly, selecting and determining a proper cabin-replacing spatial position and posture so as to carry out a damping test; determining the installation position, the number and the direction of acceleration sensors (accelerometers) in the cabin; thirdly, installing an anemoscope, an acceleration sensor and corresponding power lines and data lines on the cabin, and carrying out necessary debugging, calibration and signal transmission testing; operating the cable drive control system to enable the cabin to leave the port and run to the position near the spatial coordinate position of the cabin selected in the test by about 1 m, adjusting the cabin to a specified posture, and then locking 6 windlasses to enable the cabin to be in an air hovering state; utilizing a cable driving control system to drive the cabin replacement to move to an appointed cabin replacement position coordinate at the speed of 100mm/s, then braking and re-locking tightly, wherein the cabin cable system is in a freely damped vibration state under the action of motion inertia and generates obvious vibration acceleration and vibration displacement; sixthly, sampling and measuring acceleration vibration response and instantaneous wind speed and direction of the cabin; seventhly, completing test data recording, operating a cable drive control system, and enabling the cabin to enter the harbor; and calculating the damping of the cabin cable system according to the measured cabin-replacing vibration response data.
The method can be specifically summarized into the following four parts:
1 a data acquisition module. The data acquisition module acquires two types of data: acceleration signals collected by the acceleration sensor and wind speed and direction signals collected by the anemorumbometer;
and 2, a data transmission module. After the data acquisition module acquires the signals, the network port signals and the serial port signals are converted into optical fiber signals through photoelectric conversion and transmitted to the control room. In the control room, all signals are converted into network port signals or serial port signals again through a photoelectric converter for processing;
and 3, a data analysis module. Signals acquired in the experimental process are analyzed and processed, the vibration amplitude of the cabin-generation cable system under environmental excitation can be evaluated through recording the wind speed of the cabin-generation cable system, and the vibration amplitude is compared with the vibration amplitude generated by artificial excitation in a damping test. And performing FFT (fast Fourier transform) on the vibration signals acquired by the acceleration sensor, and then performing band-pass filtering processing on the vibration signals to calculate the cabin _ cable natural frequency and the damping ratio.
4 protocol for the experiment. The damping ratio in the identification of the structural modal parameters is greatly influenced by measurement errors, so that the identified damping ratio is always fluctuated in a larger range, and the dispersion is larger. In the measuring method, the fluctuation of the damping ratio data is effectively reduced by acquiring a plurality of measured data samples and carrying out damping identification calculation for a plurality of times. In the experimental process, a plurality of vibration tests are carried out on each cabin-replacing position, different vibration excitation modes are manufactured by driving the cabin-replacing position to approach a specified coordinate point from different directions and stopping, and various possible vibration modes of a cabin _ cable system are expected to be excited, so that the damping ratio of the identified system has wide representativeness.
The requirements for data recording in the above test process are: simultaneously recording the wind speed and the cabin-replacing acceleration in each test; through a plurality of tests, various data are effectively recorded, and analysis and subsequent repeated tests are carried out in time.
The invention mainly adopts the following instruments: SLJ-100 single component accelerometer manufactured by China earthquake Bureau engineering mechanics, GMPLUS 6 data acquisition instrument manufactured by Euramerican geodetic instruments, and FSR-2F anemorumbometer manufactured by Beijing Tianyu Kezhi. After all sensors and auxiliary hardware are installed and fixed on the cabin, the cabin is moved to a specified position and is stabilized, external excitation is applied, signals of the cabin from excitation application to stabilization are collected, the signals are analyzed and processed, and the damping ratio of the cabin _ cable system is obtained.
As shown in figure 1, because the 6 towers of the support cabin cable system are distributed into regular hexagons, the focal plane for cabin operation can be divided into 12 completely symmetrical fan-shaped areas, and therefore, one fan-shaped area is taken for testing, and the obtained result is enough to reflect the performance characteristics of the cabin cable system in the whole focal plane area. For this purpose, the 1/12 sector between the 1h tower and the 3h tower, near the 1h tower, was selected, from which 4 typical depots were determined. The WP1 point is the central point of the focal plane, namely the lowest point of the focal plane, and the cabin cable system is in an axisymmetric state at the point; WP2 point represents the point at which the focal plane edge is closest to the cabin replacement location of a support tower, where the 2 rope tensions in the 6 ropes reach maximum and minimum values, respectively, representing an extreme state of the cabin rope system; WP3 represents the edge of the focal plane at the cabin-replacing position and is positioned on an angle bisector of an included angle formed by two adjacent supporting towers, wherein the tension of 2 steel cables in 6 cables is not greatly different from the maximum value, and the other 2 steel cables are not greatly different from the minimum value and represent the other extreme state of the cabin cable system; WP4 point is the arbitrarily selected cabin-substituting position point in the sector area and represents a common state of the cabin cable system in the whole focal plane.
In the test method, the work to be completed by the technical staff comprises the following steps: selecting the type of the sensor and designing an installation interface; an experimental scheme; and (6) processing experimental data. Among them, the experimental protocol is the most important. The correct experimental scheme can save a large amount of experimental time and obtain the most accurate damping result.
Four acceleration sensors are actually installed in the test, two of the four acceleration sensors can measure three vertical directions, but because the adopted dynamic acquisition instrument only has six data channels, only two three-way sensors are used, and acceleration data of 6 channels in 3 directions are output. The sampling frequency of the dynamic collector is 200Hz, and data records of one hour are continuously collected each time, and the recording time begins from 8 am, 39 minutes and 27 seconds. The anemoscope records instantaneous wind speed and wind direction data of the top of the cabin, and the sampling frequency is that one instantaneous wind speed and instantaneous wind direction are recorded every 1 minute. The vibration amplitude of the cabin cable system under the environmental excitation can be evaluated through recording the wind speed of the cabin cable system, and compared with the vibration amplitude generated by artificial excitation in the damping test. When the vibration amplitude of the latter is attenuated to a level not much different from that of the former, the sampling of the acceleration data in the test can be stopped, and the test can be ended. The vibration of the latter can be regarded as environment excitation noise, the amplitude of the vibration signal adopted by the damping identification is obviously larger than the noise value, and the damping identification can obtain better results. As can be seen from FIG. 2, the measured ambient wind speed on the proxy cabin is mostly below 2m/s, and the 6-point proxy cabin acceleration local graph generated by excitation is obtained; as shown in fig. 3, the peak values of the accelerations in the 6 directions are mostly 0.0003g or less.
As shown in 4 diagrams of fig. 4, the acceleration response curve of the cabin cable system under free damping vibration at the WP1 position is represented, and the corresponding filtered acceleration curve and the natural frequency and damping ratio of the cabin cable system identified by the ITD time domain method are listed. In the test, 3 excitation modes are set, namely, the cabin cable system is braked from X, Y and Z direction near the WP1 point, and the speed of the cabin cable system is reduced from 100mm/s to 0 from X, Y and Z direction respectively, so that the system is excited to freely damp vibration. Because the motor of the field reflecting surface hoisting equipment is frequently started, the influence of electromagnetic interference on the acceleration sensor is large, and partial measurement data are abandoned due to poor signal to noise ratio in all 4 typical positions.
In order to enable the cabin cable system to generate enough obvious vibration acceleration, the vibration amplitude of the cabin cable system at the beginning generally far exceeds the control line difference of cable drive, at the moment, the vibration attenuation of the system is fast, the damping is large, but the actual damping ratio of the system under small amplitude (within the line difference) vibration cannot be reflected, so as to be mentioned above, acceleration curve data with the beginning peak value in the range of 0.001-0.002 g is generally selected during damping identification, and data with small fluctuation amplitude and low signal-to-noise ratio are eliminated as much as possible. In addition, in order to effectively filter the influence of measurement noise on damping identification of the cabin cable system and improve identification accuracy, offline low-pass filtering or band-pass filtering processing is carried out on the selected acceleration data through FFT (fast Fourier transform), the estimated vibration frequency of the cabin cable system is about 0.2-0.4 Hz, the upper limit cut-off frequency of the low-pass filtering can be 0.3-0.5 Hz, the lower limit cut-off frequency of the band-pass filtering can be 0.15Hz, and the upper limit can be 0.25 Hz. Under the impact excitation caused by the control cable driving sudden stop, the cabin cable system generates vibration with a plurality of frequencies, most acceleration measurement data comprise two or more main vibration frequencies, and an ITD time domain identification method is applied to each main vibration frequency and the corresponding damping ratio. In order to ensure the identification accuracy, the vibration signals of the main vibration frequencies are separated by using an off-line low-pass filtering or band-pass filtering method, and then are respectively identified.
TABLE 1
As shown in table 1, the cabin cable system natural frequency identified by the positions WP 1-WP 4 and the damping ratio parameter at the frequency are shown in table 1. It can be seen from the table that the lowest order principal vibration frequency of the nacelle cable system at these typical locations is substantially between 0.14Hz and 0.18Hz, with a corresponding damping ratio of approximately between 0.0035 and 0.0060. In addition, the cabin cable system also has a high-order natural frequency of 0.46 Hz-0.5225 Hz, and the corresponding damping ratio of 0.0032-0.0125 is generally higher than the lowest-order natural frequency. It can be seen from the measured acceleration curve frequency spectrum (fig. 4) and the conversion relationship between the acceleration and the amplitude that the amplitude of these high-order frequencies is much smaller than the lowest-order natural frequency, and the influence on the control of the positioning accuracy of the feed source support is not obvious, so that only the lowest-order natural frequency of the system and the corresponding damping ratio are concerned in the method.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the embodiments may be appropriately combined to form other embodiments understood by those skilled in the art.
Claims (1)
1. A damping test method of a FAST telescope cabin cable system is characterized by comprising the following steps: applying excitation to enable the cabin cable system to generate free damping vibration, and calculating the damping and natural vibration frequency of the cabin cable system by measuring the vibration acceleration of the cabin;
the method comprises the following steps:
step 1, selecting a substitute cabin space coordinate position and a substitute cabin space coordinate attitude to be tested on a focal plane of FAST;
step 2, determining the installation positions, the number and the directions of the anemometers and the acceleration sensors in the cabin;
step 3, installing an anemoscope, an acceleration sensor and corresponding power lines and data lines on the cabin to prepare for acquiring the instantaneous wind speed and wind direction and the acceleration vibration response of the cabin in the step 6;
step 4, operating a cable drive control system to enable the cabin to leave the port and operate to a preset position, adjusting to a specified posture, and then locking 6 windlasses to enable the cabin to be in an air hovering state; the preset position is any one point on an arc with the selected cabin-replacing space coordinate position as the center of a circle and the radius of 0.8-1.4 meters;
step 5, driving the cabin replacement to move to a designated cabin replacement space coordinate position at a speed of 100mm/s by using a cable driving control system, braking and re-braking and tightly holding, so that the cabin cable system generates free damping vibration, vibration acceleration and vibration displacement under the action of motion inertia;
step 6, sampling and measuring the acceleration vibration response and the instantaneous wind speed and direction of the cabin, and transmitting the acquired data to a control room;
step 7, completing test data recording in the control room, and operating a cable drive control system to enable the cabin to enter the harbor;
step 8, inversely calculating the damping and the natural vibration frequency of the cabin cable system at the cabin space coordinate position according to the measured cabin-replacing vibration response data, thereby obtaining the cabin cable system damping by using an ITD time domain identification method;
after the signals are collected in the step 6, converting the network port signals and the serial port signals into optical fiber signals through photoelectric conversion, and transmitting the optical fiber signals to a control room; in the step 7, in the control room, all signals are converted into network port signals or serial port signals again through the photoelectric converter for processing;
analyzing and processing the acquired signals in the step 8:
the vibration amplitude of a cabin cable system under environmental excitation is evaluated through recording the cabin-replacing wind speed, and is compared with the vibration amplitude generated by artificial excitation in a damping test, so that the vibration signal acquired by an acceleration sensor is determined; and performing FFT (fast Fourier transform) on the vibration signals acquired by the acceleration sensor, and then performing band-pass filtering processing on the vibration signals, and calculating the inherent vibration frequency and the damping ratio of the cabin cable system.
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2019
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| JP2009092398A (en) * | 2007-10-04 | 2009-04-30 | Yokohama Rubber Co Ltd:The | Method for evaluating vibration damping performance of object |
| CN102506986A (en) * | 2011-12-02 | 2012-06-20 | 江苏方天电力技术有限公司 | Test system and method for mode and vibration of self-supporting tower and large-span power transmission tower |
| CN102790600A (en) * | 2012-07-13 | 2012-11-21 | 中国科学院国家天文台南京天文光学技术研究所 | Detecting and filtering method for nonlinear disturbance of large-caliber telescope |
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