CN105758322A - Antenna field rotary table deformation monitoring apparatus and method based on fiber grating sensor - Google Patents

Abstract

The invention discloses an antenna field rotary table deformation monitoring apparatus and method based on a fiber grating sensor. The apparatus comprises a fiber grating strain sensor, a fiber grating temperature sensor, a fiber network, an optical switch matrix, a fiber grating demodulator and an industrial control computer. The fiber grating strain sensor and the temperature sensor are arranged in an antenna field rotary table structure; the strain sensor and the temperature sensor, after multiplexing through the optical switch matrix, are then connected with the fiber grating demodulator; and the industrial control computer is used for positioning a position where a rotary table deforms according to output of the fiber grating demodulator and controlling conduction of the optical switch matrix. The apparatus can perform comprehensive monitoring on the deformation of the rotary table, gives an early warning about the time and the position of the deformation of the rotary table, and has great significance in guaranteeing safety of the rotary table and test personnel.

Description

Antenna field turntable deformation monitoring apparatus and method based on fiber-optic grating sensor

Technical field

The present invention relates to detection technique, particularly relate to a kind of antenna field turntable deformation monitoring apparatus and method based on fiber-optic grating sensor.

Background technology

Antenna field turntable in use, is subject to the sun for a long time and is exposed to the sun and raindrop erosion, causes turntable structure to deform upon and intensity reduces, and then affects turning table control precision and threaten turntable to use safety so that turntable structure damage and fatigue rupture monitoring are particularly significant.At present, along with the development of sensor technology and the network communications technology, the safety evaluation of Chinese large-sized structure is developed to real time on-line monitoring analysis directions by traditional regular safety check (nondestructive inspection and artificial inspection).

Antenna field turntable deformation monitoring system can measure and record the stressing conditions of monitoring point in real time, and carries out a degree of security evaluation and safe early warning.But, owing to traditional strain transducer itself has certain weight, distortion measurements is easily caused impact；The limited amount of monitoring point, its position is chosen and is difficult to reach optimum, it is easy to cause that some structure position safety declines and can not be found in time so that turntable operationally exists potential safety hazard.

Summary of the invention

The technical problem to be solved in the present invention is in that for defect of the prior art, it is provided that a kind of antenna field turntable deformation monitoring apparatus and method based on fiber-optic grating sensor.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of antenna field turntable deformation monitoring device based on fiber-optic grating sensor, including: fiber Bragg grating strain sensor, fiber-optical grating temperature sensor, fiber optic network, optical switch matrix, fiber Bragg grating (FBG) demodulator and industrial computer；

Described fiber Bragg grating strain sensor and temperature sensor are arranged in antenna field turntable structure；

Described strain transducer and temperature sensor are connected with fiber Bragg grating (FBG) demodulator after optical switch matrix multiplexes again；

The position that described industrial computer deforms upon for the output location turntable according to fiber Bragg grating (FBG) demodulator, and control the conducting of optical switch matrix.

A kind of antenna field turntable deformation monitoring method based on fiber-optic grating sensor, comprises the following steps:

1) in antenna field turntable structure, a number of fiber Bragg grating strain sensor and temperature sensor are disposed；

2) the multiple fiber Bragg grating strain sensors that will be distributed on turntable access fiber grating demodulation device with temperature sensor through optical-fiber network after optical switch matrix multiplexes；

3) receive the data of fiber grating demodulation device output, by frequency method strain be identified and position, specific as follows:

3.1) by fiber Bragg grating strain sensor record axial strain；Axial strain adopts following formula to calculate:

ε_x=Δ λ/λ₀(1-P_e)

Wherein, Δ λ is wave length shift, wavelength centered by λ 0, and Pe is optical fiber elasto-optical coefficient；

3.2) set turntable girder construction oscillation crosswise the i-th rank principal oscillation as:

In formula, Y_iX () is model function of vibration, ω_iFor natural mode of vibration,For phase angle, x is the coordinate figure in beam length direction；

Then: in the i-th rank principal oscillation, the kinetic energy of beam is

In formula (2), ρ is density of material, and A is the cross-sectional area of beam；

The elastic potential energy of beam is

In formula (3), E is the elastic modelling quantity of beam, and I is the moment of inertia in the cross section of beam；

3.3) maximum kinetic energy and maximum flexibility potential energy by the i-th rank principal oscillation are

$T_{i,max}=\frac{1}{2}{\mathrm{\ω}}_i^2{\∫}_0^l{\mathrm{\ρAY}}_i^{2}dx---\left(4\right)$

$U_{i,max}=\frac{1}{2}{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}dx---\left(5\right)$

3.4) according to conservation of mechanical energy in principal oscillation, i.e. T_i,max=U_i,max?

$\frac{1}{2}{\mathrm{\ω}}_i^2{\∫}_0^l{\mathrm{\ρAY}}_i^{2}dx=\frac{1}{2}{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}dx---\left(6\right)$

Solve formula (6) can obtain:

${\mathrm{\ω}}_i^2=\frac{{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}\left(x\right)dx}{{\∫}_0^l{\mathrm{\ρAY}}_i^2\left(x\right)dx}---\left(7\right);$

The rate of change of natural frequency f with-| Y_i" | variation tendency be similar to, it may be assumed that

$\frac{{\mathrm{\δf}}_2}{{\mathrm{\δf}}_1}\≈\frac{\left|Y_2^{\′\′}\right|}{\left|Y_1^{\′\′}\right|},\frac{{\mathrm{\δf}}_3}{{\mathrm{\δf}}_1}\≈\frac{\left|Y_3^{\′\′}\right|}{\left|Y_1^{\′\′}\right|}---\left(8\right)$

δ f in formula_i(i=1～3) are the rate of change of structure the i-th rank natural frequency；

3.5) when girder construction not damaged, the camber mode on each rank is calculated according to formula (7)；δ f is calculated by formula (8) when girder construction is damaged₂/δf₁With δ f₃/δf₁With the variation tendency of damage position, described damage position is historical data；

With damage position normalization coordinate for abscissa, with δ f₂/δf₁With δ f₃/δf₁For vertical coordinate, obtain 2 reference curves. by measure girder construction lossless time natural frequency and natural frequency when damaging, it is possible to calculate the ratio delta f of frequency change rate₂/δf₁With δ f₂/δf₁, do straight line with the ratio of frequency change rate, if obtaining the intersection point with reference curve. and δ f₂/δf₁With δ f₂/δf₁Intersection point in have the situation that coordinate is close, then it is assumed that be one of possible position of existing of damage under this coordinate；For symmetrical structure, point of symmetry are had at least to be probably undamaged；For unsymmetric structure, may recognize that damage position.

4) if turntable deforms upon, control optical switch matrix, adjust the sensor distribution situation of deformation happening part；

5) statistic law is utilized to set up the corresponding relation between trend and the ambient temperature that turntable deforms upon；

6) ambient temperature that the statistical law deformed upon according to historical data and turntable, and fiber-optical grating temperature sensor collects, the time and the positions that occur turntable deformation carry out early warning.

By such scheme, step 1) in, the deployed position of fiber Bragg grating strain sensor and temperature sensor and quantity basis the calculated results.

The beneficial effect comprise that:

1. by optical switch matrix is controlled, it is possible to adjust quantity and the distribution situation of effective fiber grating sensor in real time, improve the precision of monitoring in real time to greatest extent；

2. by historical data is carried out statistics and analysis, the time and the positions that occur turntable deformation carry out early warning, to ensureing that turntable and tester's safety are significant.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the invention will be further described, in accompanying drawing:

Fig. 1 is the structural representation of the embodiment of the present invention；

Fig. 2 FBG senses ultimate principle figure；

Fig. 3 is FBGs strain transducer measuring principle figure.

Detailed description of the invention

In order to make the purpose of the present invention, technical scheme and advantage clearly understand, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein is only in order to explain the present invention, is not intended to limit the present invention.

As it is shown in figure 1, a kind of antenna field turntable deformation monitoring system based on fiber-optic grating sensor is made up of fiber Bragg grating strain sensor, fiber-optical grating temperature sensor, fiber optic network, optical switch matrix, fiber Bragg grating (FBG) demodulator, industrial computer (containing online-monitoring software).

Described fiber Bragg grating strain sensor and temperature sensor are arranged in antenna field turntable structure；

Described strain transducer and temperature sensor are connected with fiber Bragg grating (FBG) demodulator after optical switch matrix multiplexes again；

The position that described industrial computer deforms upon for the output location turntable according to fiber Bragg grating (FBG) demodulator, and control the conducting of optical switch matrix.

Its operation principle is as follows: the quantity of fiber Bragg grating strain sensor and fiber-optical grating temperature sensor and distribution set according to the calculated results, carries out fiber grating demodulation after being multiplexed by optical-fiber network and optical switch matrix.The data that the demodulation of online-monitoring software analyte sensors is later, utilize frequency method strain is identified and positions, and by controlling optical switch matrix, adjust the distribution situation of strain happening part sensor, improve precision and the efficiency of turntable deformation monitoring；Utilizing statistic law to set up the corresponding relation between trend and the ambient temperature that its turntable deforms upon, the time and the positions that occur turntable deformation carry out early warning, thus ensureing turntable and tester's safety.

Adopt a kind of antenna field turntable deformation monitoring method of the above-mentioned antenna field turntable deformation monitoring device based on fiber-optic grating sensor, comprise the following steps:

1) a number of fiber grating strain and temperature sensor, position and quantity basis the calculated results are disposed at the key position of antenna field turntable structure；

2) it is distributed in the multiple fiber grating strains on turntable and temperature sensor and accesses fiber grating demodulation device after optical-fiber network and optical switch matrix multiplex；

3) use online-monitoring software to analyze the data of fiber grating demodulation device output, by frequency method strain be identified and position, specific as follows:

Fiber-optic grating sensor makes strain transducer, and its reflective Fresnel Fiber Bragg Grating FBG is under external pressure, and the cycle of fiber grating increases due to the physical extension of optical fiber, and the result of this change is shown as the drift of a Bragg wavelength, as shown in Figure 2.

Therefore, shown in axial strain expression formula following formula.

ε_x=Δ λ/λ₀(1-P_e)

Wherein, Δ λ is wave length shift, wavelength centered by λ 0, and Pe is optical fiber elasto-optical coefficient, for typical single-mode quartz optical fibers Pe=0.22).

FBG is used as strain transducer as it is shown on figure 3, measurement process needs amplified spontaneous emission source (ASE) and optical spectrum analyser (OSA) obtain and record dynamic strain.

If the i-th rank principal oscillation of the oscillation crosswise of turntable girder construction is:

In formula, Y_iX () is model function of vibration, ω_iFor natural mode of vibration,For phase angle, x is the coordinate figure in beam length direction.

In the i-th rank principal oscillation, the kinetic energy of beam is

In formula (2), ρ is density of material, and A is the cross-sectional area of beam.

The elastic potential energy of beam is

In formula (3), E is the elastic modelling quantity of beam, and I is the moment of inertia in cross section.

By the maximum kinetic energy of the known i-th rank principal oscillation of formula (2) and formula (3) and maximum flexibility potential energy it is

$T_{i,max}=\frac{1}{2}{\mathrm{\ω}}_i^2{\∫}_0^l{\mathrm{\ρAY}}_i^{2}dx---\left(4\right)$

$U_{i,max}=\frac{1}{2}{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}dx---\left(5\right)$

According to conservation of mechanical energy in principal oscillation, i.e. T_i,max=U_i,max?

$\frac{1}{2}{\mathrm{\ω}}_i^2{\∫}_0^l{\mathrm{\ρAY}}_i^{2}dx=\frac{1}{2}{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}dx---\left(6\right)$

Solve formula (6) can obtain:

${\mathrm{\ω}}_i^2=\frac{{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}\left(x\right)dx}{{\∫}_0^l{\mathrm{\ρAY}}_i^2\left(x\right)dx}---\left(7\right)$

Y in formula_i" (x) is camber mode, and when the somewhere of beam exists damage, I value can change.

When girder construction exist damage time, namely its somewhere cross sectional moment of inertia I will reduce, by formula (7) it can be seen that girder construction damage after its natural frequency can reduce.When injury region is positioned at the bigger position of curvature mode shape, natural frequency declines bigger；When injury region is positioned at the less position of curvature mode shape, natural frequency declines less；When injury region is positioned at curvature mode shape node location, natural frequency is held essentially constant. and this illustrates that this damage position causes the change of natural frequency relevant to curvature mode shape, in a certain degree when girder construction exists damageChanging Pattern withLinear.

The rate of change of natural frequency f with-| Y_i" | variation tendency be similar to, it may be assumed that

$\frac{{\mathrm{\δf}}_2}{{\mathrm{\δf}}_1}\≈\frac{\left|Y_2^{\′\′}\right|}{\left|Y_1^{\′\′}\right|},\frac{{\mathrm{\δf}}_3}{{\mathrm{\δf}}_1}\≈\frac{\left|Y_3^{\′\′}\right|}{\left|Y_1^{\′\′}\right|}---\left(8\right)$

δ f in formula_i(i=1～3) are the rate of change of structure the i-th rank natural frequency.

When girder construction not damaged, calculate the camber mode on each rank, formula (8) calculate δ f₂/δf₁With δ f₃/δf₁Variation tendency with damage position. with damage position normalization coordinate for abscissa, with δ f₂/δf₁With δ f₃/δf₁For vertical coordinate, obtain 2 reference curves. by measure girder construction lossless time natural frequency and natural frequency when damaging, it is possible to calculate the ratio delta f of frequency change rate₂/δf₁With δ f₂/δf₁, do straight line with the ratio of frequency change rate, if obtaining the intersection point with reference curve. and δ f₂/δf₁With δ f₂/δf₁Intersection point in have the situation that coordinate is close, then it is assumed that be one of possible position of existing of damage under this coordinate. for symmetrical structure, have at least point of symmetry to be probably undamaged；For unsymmetric structure, may recognize that damage position.

4) if turntable deforms upon, control optical switch matrix, adjust the sensor distribution situation of deformation happening part；

5) statistic law is utilized to set up the corresponding relation between trend and the ambient temperature that turntable deforms upon；

6) ambient temperature that the statistical law deformed upon according to historical data and turntable, and fiber-optical grating temperature sensor collects, the time and the positions that occur turntable deformation carry out early warning；

7) according to early warning, turntable is safeguarded, it is possible to ensure turntable and tester's safety, extend turntable life cycle.

It should be appreciated that for those of ordinary skills, it is possible to improved according to the above description or converted, and all these are improved and convert the protection domain that all should belong to claims of the present invention.

Claims (3)

1. the antenna field turntable deformation monitoring device based on fiber-optic grating sensor, it is characterised in that including:

Fiber Bragg grating strain sensor, fiber-optical grating temperature sensor, fiber optic network, optical switch matrix, fiber Bragg grating (FBG) demodulator and industrial computer；

Described fiber Bragg grating strain sensor and temperature sensor are arranged in antenna field turntable structure；

Described strain transducer and temperature sensor are connected with fiber Bragg grating (FBG) demodulator after optical switch matrix multiplexes again；

The position that described industrial computer deforms upon for the output location turntable according to fiber Bragg grating (FBG) demodulator, and control the conducting of optical switch matrix.

2., based on an antenna field turntable deformation monitoring method for fiber-optic grating sensor, comprise the following steps:

1) in antenna field turntable structure, a number of fiber Bragg grating strain sensor and temperature sensor are disposed；

2) the multiple fiber Bragg grating strain sensors that will be distributed on turntable access fiber grating demodulation device with temperature sensor through optical-fiber network after optical switch matrix multiplexes；

3) receive the data of fiber grating demodulation device output, by frequency method strain be identified and position；

4) if turntable deforms upon, control optical switch matrix, adjust the sensor distribution situation of deformation happening part；

5) statistic law is utilized to set up the corresponding relation between trend and the ambient temperature that turntable deforms upon；

6) ambient temperature that the statistical law deformed upon according to historical data and turntable, and fiber-optical grating temperature sensor collects, the time and the positions that occur turntable deformation carry out early warning.

3. the antenna field turntable deformation monitoring method based on fiber-optic grating sensor according to claim 2, it is characterised in that by frequency method to specifically comprising the following steps that strain is identified and positions

3.1) by fiber Bragg grating strain sensor record axial strain；Axial strain adopts following formula to calculate:

ε_x=Δ λ/λ₀(1-P_e)

Wherein, Δ λ is wave length shift, wavelength centered by λ 0, and Pe is optical fiber elasto-optical coefficient；

3.2) set turntable girder construction oscillation crosswise the i-th rank principal oscillation as:

In formula, Y_iX () is model function of vibration, ω_iFor natural mode of vibration,For phase angle, x is the coordinate figure in beam length direction；

Then: in the i-th rank principal oscillation, the kinetic energy of beam is

In formula (2), ρ is density of material, and A is the cross-sectional area of beam；

The elastic potential energy of beam is

In formula (3), E is the elastic modelling quantity of beam, and I is the moment of inertia in the cross section of beam；

3.3) maximum kinetic energy and maximum flexibility potential energy by the i-th rank principal oscillation are

$T_{i,\max }=\frac{1}{2}{\mathrm{\ω}}_i^2{\∫}_0^l{\mathrm{\ρAY}}_i^{2}dx---\left(4\right)$

$U_{i,max}=\frac{1}{2}{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}dx---\left(5\right)$

3.4) according to conservation of mechanical energy in principal oscillation, i.e. T_i,max=U_i,max?

$\frac{1}{2}{\mathrm{\ω}}_i^2{\∫}_0^l{\mathrm{\ρAY}}_i^{2}dx=\frac{1}{2}{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}dx---\left(6\right)$

Solve formula (6) can obtain:

${\mathrm{\ω}}_i^2=\frac{{\∫}_0^l{\mathrm{EIY}}_i^{\′\′2}\left(x\right)dx}{{\∫}_0^l{\mathrm{\ρAY}}_i^2\left(x\right)dx}---\left(7\right);$

The rate of change of natural frequency f with-| Y_i" | variation tendency be similar to, it may be assumed that

$\frac{{\mathrm{\δf}}_2}{{\mathrm{\δf}}_1}\≈\frac{\left|Y_2^{\′\′}\right|}{\left|Y_1^{\′\′}\right|},\frac{{\mathrm{\δf}}_3}{{\mathrm{\δf}}_1}\≈\frac{\left|Y_3^{\′\′}\right|}{\left|Y_1^{\′\′}\right|}---\left(8\right)$

δ f in formula_i(i=1～3) are the rate of change of structure the i-th rank natural frequency；

3.5) when girder construction not damaged, the camber mode on each rank is calculated according to formula (7)；δ f is calculated by formula (8) when girder construction is damaged₂/δf₁With δ f₃/δf₁With the variation tendency of damage position, described damage position is historical data.