CN106247921B - High-precision bridge deformation detection method based on RF phse measuring technique - Google Patents

Abstract

The invention relates to a bridge deformation detection method, comprising: installing a radio frequency transmitting device and a radio frequency receiving device on the pier of each span of the bridge, installing two radio frequency transmitting devices and a radio frequency receiving device on the other side, Several RF receiving devices are installed at the mid-span measurement point; the RF receiving device on each pier of each side of the bridge receives the RF signal from the RF transmitting device on the same side of the same span, and the RF receiving device at the mid-span measurement point receives The radio frequency signal of the radio frequency transmitting device of the side pier; the radio frequency receiving device measures the phase of the radio frequency signal, determines the distance between the radio frequency transmitting device and the radio frequency receiving device of each bridge pier on the same side, and calculates the frequency deviation according to this distance; according to the frequency deviation, the radio frequency transmission The measured distance from the device to the RF receiving device at the mid-span measurement point is corrected; the position coordinate value of the RF receiving device at the mid-span measurement point is calculated according to the corrected measured distance; the bridge deformation value is calculated according to the position coordinate value.

Description

High-precision bridge deformation detection method based on radio frequency phase measurement technology

technical field

The invention relates to the fields of bridge monitoring and radio frequency distance measurement, in particular to a high-precision bridge deformation detection method based on radio frequency phase measurement technology.

Background technique

Real-time deformation monitoring of large bridges is very necessary during bridge construction and operation. Through real-time deformation monitoring of large bridge structures, the deformation and deformation laws of the bridge can be grasped, so as to ensure the safe and healthy operation of the bridge structure and avoid the occurrence of catastrophic accidents; The verification of design rationality and the evaluation of bridge operating life and bearing capacity are of great practical significance. At present, the traditional monitoring methods of bridge deformation mainly include sensors, accelerometers, conventional geodetic technology, laser interferometer, conventional geodetic (total station, precision level), etc.; with the development of science and technology and the progress of space technology, there are Modern measurement methods such as GPS technology and synthetic aperture radar interferometry technology have been developed. Although these measurement methods have their own characteristics and application environments, they also have their limitations and cannot fully meet the requirements of continuous (multi-point), high-frequency (high-frequency), and real-time (dynamic) measurement of bridge vibration.

Contents of the invention

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a continuous, high-frequency, real-time, high-precision bridge deformation detection method based on radio frequency phase measurement, which can meet the real-time, all-weather, high-precision, long-term stable automatic monitoring of bridge deformation requirements.

To achieve the above object, the present invention can be achieved through the following technical solutions:

A high-precision bridge deformation detection method based on radio frequency phase measurement technology, including the following steps:

(1) Install one radio frequency transmitting device and one radio frequency receiving device on one pier of each span of the bridge, install two radio frequency transmitting devices and one radio frequency receiving device on the other side of the bridge pier, and install several radio frequency devices at the mid-span measurement point receiving equipment;

(2) The RF receiving equipment on each bridge pier on each side of the bridge receives the RF signal from the RF transmitting equipment on the same side of the bridge pier, and the RF receiving equipment on the mid-span measurement point receives the RF signal from the RF transmitting equipment on both sides of the same span. Signal;

(3) The radio frequency receiving equipment on the bridge pier measures the phase of the radio frequency signal, and determines the round ambiguity according to the characteristics of the frequency, so as to determine the distance from the radio frequency transmitting equipment to the radio frequency receiving equipment on each bridge pier on the same side, and calculate the frequency based on this distance. Partial;

(4) According to the frequency offset, the measured distances from the radio frequency transmitting equipment of the piers on both sides to the radio frequency receiving equipment of the mid-span measurement point are corrected;

(5) Calculate the position coordinate value of the radio frequency receiving equipment of the mid-span measurement point according to the measured distance after the correction of step (4);

(6) Calculate the bridge deformation value according to the position coordinate value of the radio frequency receiving equipment at the mid-span measurement point.

Further, all radio frequency transmitting devices emit electromagnetic waves of two frequencies, the frequencies are f ₁ and f ₂ respectively, f ₁ is the fine frequency, f ₂ is the coarse frequency, and the corresponding wavelengths are λ ₁ and λ ₂ respectively, the frequency The selection principles are as follows:

λ ₂ >D (1)

Among them: d is the minimum accuracy value required by the measurement; D is a value of the order of meters, which is not only far greater than the maximum deformation value of the measured bridge, but also far greater than the error value of manual measurement; M ₁ is the corresponding frequency f ₁ Phase measurement accuracy, M ₂ is the phase measurement accuracy corresponding to frequency f ₂ .

Further, assume that the number of a radio frequency transmitting device on one side of the bridge is 1, and the number of one radio frequency receiving device is %1; the numbers of the two radio frequency transmitting devices on the other side of the bridge are 2 and 3, and the number of one radio frequency receiving is %2; the radio frequency transmitting equipment and the radio frequency receiving equipment on the same side are separated by distances D _{1,% 1} , D _{2,% 2} and D _{3,% 2} satisfy the following conditions:

where c is the speed of light in vacuum.

Furthermore, the radio frequency signal is formed by the data code being modulated by spread spectrum with the gold code, and then modulated by the carrier BPSK.

Further, in step (3), it is assumed that a frequency offset Δf _i,(j) occurs at the transmitting frequency f _i,(j) (i=1,2) of the radio frequency transmitting device j (j=1,2,3), The RF receiving device k (for RF transmitting device 1, k=%1; for RF transmitting devices 2 and 3, k=%2) measures the phase difference as but:

where: c is the speed of light in vacuum, is the measured integer ambiguity, is the distance between RF transmitting device j and RF receiving device k measured at frequency f _i,(j) +Δf _i,(j) , is the actual distance;

Use the following formula to calculate the frequency offset:

in: Indicates the actual frequency;

Since D is a value of the order of meters, which is far greater than the error value of manual measurement, according to the conditions stipulated in (4), (5) and (6), it is determined by the method of manual measurement as well as

Further, in step (4), the measured distances from the radio frequency transmitting equipment j of the piers on both sides to the radio frequency receiving equipment m (m=#1, #2, #3,...) of the mid-span measurement point are:

in: is the integer ambiguity, is the phase difference.

Further, for the frequency f ₂ , the round ambiguity of phase detection Obtained by manual methods, due to different measurement accuracy and and There are two relations:

③ at this time

so Take the maximum value that satisfies formula (11);

④ at this time

so Take the minimum value that satisfies formula (12);

OK After that, it is calculated by formula (10)

Further, in step (5), under the condition that the coordinates (x _j , y _j , z _j ) of the radio frequency transmitting device j are known, the coordinates (x _m , y _m , z _m ) of the radio frequency receiving device m can be obtained by Determined by the following formula:

The present invention can realize long-distance high-precision bridge deformation measurement, solves the problem of complex layout and high cost of bridge deformation monitoring system in the prior art, has the advantages of continuous, high-frequency, real-time, high-precision, etc., and satisfies real-time, All-weather, high-precision, and long-term stable automatic monitoring requirements realize the health monitoring of bridges.

Description of drawings

Figure 1 is a top view of the equipment installation;

Fig. 2 is the schematic diagram of gold code generator;

Fig. 3 is a composition diagram of the data code transmitted by the radio frequency transmitting device;

Fig. 4 is the relationship diagram between carrier wave, golden code and data code;

Fig. 5 is a data composition diagram transmitted to the remote monitoring module;

Fig. 6 is a schematic diagram of the system of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

The high-precision bridge deformation detection method based on radio frequency phase measurement technology of the present invention comprises the following steps:

(1) Install one radio frequency transmitting device and one radio frequency receiving device on the pier on each side of the bridge (called side A), and install two radio frequency transmitting devices and one radio frequency on the other side of the pier (called side B) Receiving equipment, install several radio frequency receiving equipment at the mid-span measurement point.

All radio frequency transmitting equipment emits electromagnetic waves of two frequencies, the frequencies are f ₁ and f ₂ respectively, f ₁ is the fine frequency, f ₂ is the coarse frequency, and the corresponding wavelengths are λ ₁ and λ ₂ respectively. :

λ ₂ >D (1)

Among them: d is the minimum accuracy value required by the measurement; D is a value of the order of meters, which is not only far greater than the maximum deformation value of the measured bridge, but also far greater than the error value of manual measurement; M ₁ is the corresponding frequency f ₁ Phase measurement accuracy, M ₂ is the phase measurement accuracy corresponding to frequency f ₂ .

Assume that the number of one radio frequency transmitting device on side A is 1, and the number of one radio frequency receiving device is %1; the numbers of two radio frequency transmitting devices on side B are respectively 2 and 3, and the number of one radio frequency receiving device is %2; on the same side The distances D _{1,% 1} , D _{2,% 2} and D _{3,% 2} between the radio frequency transmitting equipment and the radio frequency receiving equipment meet the following conditions:

(2) The RF receiving equipment on each bridge pier on each side of the bridge receives the RF signal from the RF transmitting equipment on the same side of the bridge pier, and the RF receiving equipment on the mid-span measurement point receives the RF signal from the RF transmitting equipment on both sides of the same span. Signal. The radio frequency receiving equipment can receive the frequency signals of f ₁ and f ₂ at the same time. The radio frequency receiving equipment on side A has only one signal channel for each frequency, and only accepts the radio frequency signal of the radio frequency transmitting equipment on side A. The radio frequency receiving equipment on side B Each frequency has 2 signal channels, and only accepts the radio frequency signals of the 2 radio frequency transmitting devices on side B. Corresponding radio frequency receiving equipment (device number: #1, #2, #3, ...) is fixedly installed at the mid-span measurement point to receive frequency signals of f ₁ and f ₂ at the same time, and each frequency has 3 signal channels, which are respectively received The radio frequency signals of 3 radio frequency transmitting devices.

In order to realize the precise synchronization of data, the radio frequency signal data is composed of synchronization code, equipment identification code and time marking code. Design a gold code generator. The gold code generated by each radio frequency transmitting device is different. After the gold code is generated, spread spectrum modulation is performed on the data code, and then f ₁ and f ₂ frequency signals are used as carriers, and BPSK is performed on the spread spectrum modulated signal Modulate, then launch.

(3) The radio frequency receiving equipment on the bridge pier measures the phase of the radio frequency signal, and determines the round ambiguity according to the characteristics of the frequency, so as to determine the distance from the radio frequency transmitting equipment to the radio frequency receiving equipment on each bridge pier on the same side, and calculate the frequency based on this distance. Partial.

After the radio frequency receiving equipment receives the radio frequency signal, it strips the digital intermediate frequency signal through frequency mixing, determines the signal channel according to the gold code, performs correlation calculation to strip the gold code in the signal, and the rest is the data code modulated by BPSK; Perform phase measurements at the same time to obtain the phase difference corresponding to f ₁ and f ₂ frequencies and Add the received data code to the device identification code of the radio frequency receiving device itself, and A new data code is formed and transmitted to the remote monitoring module through the communication module for data processing.

Assume that a frequency offset Δf _i,(j ) occurs at the transmitting frequency f _i,(j) (i=1,2) of the radio frequency transmitting device j (j=1,2,3), and the radio frequency receiving device k (for the radio frequency transmitting device 1, k=%1; for radio frequency transmitting equipment 2 and 3, k=%2) The measured phase difference is but:

where: c is the speed of light in vacuum, is the measured integer ambiguity, is the distance between the RF transmitting device j and the RF receiving device k measured at frequency f _i,(j) +Δf _i,(j) , is the actual distance;

Use the following formula to calculate the frequency offset:

in: Indicates the actual frequency.

Since D is a value of the order of meters, which is far greater than the error value of manual measurement, according to the conditions specified in (4), (5) and (6), it can be determined by manual measurement

(4) According to the frequency offset, the measured distances from the radio frequency transmitting equipment on the piers on both sides to the radio frequency receiving equipment at the mid-span measurement point are corrected.

The measured distance from the radio frequency transmitting equipment j of the pier on both sides to the radio frequency receiving equipment m (m=#1, #2, #3,...) of the mid-span measurement point is:

in: is the integer ambiguity, is the phase difference.

For frequency f ₂ , the round ambiguity in phase detection It can be obtained by manual measurement, due to different measurement accuracy and and There are two relations:

① at this time

so Take the maximum value that satisfies formula (11);

② at this time

so Take the minimum value that satisfies formula (12);

OK After that, it is calculated by formula (10)

(5) Calculate the position coordinate value of the radio frequency receiving device at the mid-span measurement point according to the corrected measured distance in step (4).

Under the condition of knowing the j coordinates (x _j , y _j , z _j ) of the radio frequency transmitting equipment, the coordinates of m (x _m , y _m , z _m ) can be determined by the following formula

(6) Calculate the bridge deformation value according to the position coordinate value of the radio frequency receiving equipment at the mid-span measurement point.

Embodiment one

As shown in Figure 1, consider a certain span of a bridge with a span of 300m, one radio frequency transmitting device is fixedly installed on one side of the bridge span (side A, number: 1), and two radio frequency transmitters are fixedly installed on the other side (side B , No.: 2, 3), the two public radio frequencies are 315MHz and 433MHz, the two frequencies can be combined into f ₁ = 748MHz as the fine frequency, and f ₂ = 118MHz as the coarse frequency; one radio frequency receiver is fixedly installed on each side of the pier on both sides Equipment (number of side A: %1, number of side B: %2), the distance between the radio frequency receiving device and the radio frequency transmitting device is greater than 0.4m, the radio frequency receiving device of side B has 2 signal channels, and the radio frequency receiving device of side A has 1 Signal channel; install a radio frequency receiving device (number: #1) in the middle of the span, and this receiver has 3 signal channels.

RF transmitting device 1 generates gold codes according to the schematic diagram in Figure 2. At this time, the leftmost switch is closed, and the rest are disconnected. RF transmitting device 2 generates gold codes according to the schematic diagram in Figure 2. Open, the radio frequency transmitting device 3 generates a gold code according to the schematic diagram in Figure 2, at this time the third switch on the left is closed, and the rest are disconnected; fill in the data code according to Figure 3, the radio frequency transmitting device identification code of the radio frequency transmitting device 1 is 00000001, the radio frequency The radio frequency transmitting device identification code of the transmitting device 2 is 00000010, and the radio frequency transmitting device identification code of the radio frequency transmitting device 3 is 00000011; the time identification code starts from 00000000 and fills in sequentially by adding 1, and adds 1 to 11111111 to become 00000000 again. Carry out spread spectrum modulation on the data code according to Fig. 4, then use f ₁ and f ₂ frequency signals as carrier, carry on BPSK modulation to the spread spectrum modulation signal, and then transmit it.

Since the distance between radio frequency transmitting equipment 1 and radio frequency receiving equipment %1 is fixed, the frequency deviation of f1 and f2 of radio frequency transmitting equipment ₁ can be determined according to formula (9); the same principle can determine f1 and f _of radio frequency transmitting equipment ₂ and 3 ₂ frequency offset.

The phase measurement accuracy of radio frequency receiving equipment #1 is M=1/100 for coarse frequency, M=1/100 for fine frequency, the scale range of coarse frequency measurement is 0.0125-2.5m, and the scale range of fine frequency measurement is 0.002- 0.4m. Since λ ₂ ≥ 2.5m, which is far greater than the maximum deformation of the bridge (the maximum deformation of the bridge is on the order of millimeters, and it is also far greater than the error value of manual detection), so the radio frequency transmitting equipment 1, 2, and 3 are measured with the coarse frequency f ₂ The integer ambiguity at the distance of RF receiving device #1 can be obtained by manual measurement, and the distance obtained accordingly is the coarse distance; then the distance can be obtained by measuring the distance with fine frequency value, resulting in submillimeter distances.

According to Figure 5, fill in the corresponding data, wherein the radio frequency receiving device identification code of the radio frequency receiving device #1 is 00000001.

According to Figure 6, the data is transmitted to the management device through the communication device, and the management device groups the data according to the device identification code and time identification code according to the received data, and then calculates the coordinates of the radio frequency receiving equipment #1 according to the formula (13) position to get the bridge deformation value.

For those skilled in the art, various other corresponding changes and modifications can be made according to the above technical solutions and ideas, and all these changes and modifications should fall within the protection scope of the claims of the present invention.

Claims (8)

1. the high-precision bridge deformation detection method based on RF phse measuring technique, which comprises the following steps:

(1) in bridge, often across side bridge pier installs a radio frequency emitting devices and a radio frequency reception equipment, in other side bridge pier Two radio frequency emitting devices and a radio frequency reception equipment are installed, several radio frequency reception equipment are installed in span centre measurement point；

(2) often the radio frequency reception equipment across every side bridge pier is received from the same radio frequency emitting devices across the same side bridge pier bridge Radiofrequency signal, the radio frequency reception equipment of span centre measurement point receives the radio frequency from the same radio frequency emitting devices across two sides bridge pier Signal；

(3) the radio frequency reception equipment on bridge pier carries out phase measurement to radiofrequency signal, the characteristics of according to frequency, determines week mould preparation paste Degree, so that it is determined that the radio frequency emitting devices often across ipsilateral bridge pier calculate frequency deviation according to this distance to the distance of radio frequency reception equipment；

(4) arrived respectively according to radio frequency emitting devices of the frequency deviation to two sides bridge pier the actual measurement of the radio frequency reception equipment of span centre measurement point away from From being modified；

(5) position coordinate value of the radio frequency reception equipment of span centre measurement point is calculated according to step (4) revised measured distance；

(6) bridge deformation value is calculated according to the position coordinate value of the radio frequency reception equipment of span centre measurement point.

2. high-precision bridge deformation detection method according to claim 1, it is characterised in that: all radio frequency emitting devices are equal Emit the electromagnetic wave of two kinds of frequencies, frequency is respectively f₁And f₂, f₁For smart frequency, f₂For thick frequency, corresponding wavelength is respectively λ₁With λ₂, the selection principle of frequency is as follows:

λ₂> D (1)

Wherein: d is the minimum accuracy value of measurement request；D is the value of a rice order of magnitude, this value is not only far longer than tested bridge Maximum deformation value, and it is far longer than the error amount of manual measurement；M₁It is frequency f₁Corresponding phase-measurement accuracy, M₂It is frequency f₂It is right The phase-measurement accuracy answered.

3. high-precision bridge deformation detection method according to claim 2, it is characterised in that: assuming that one of side bridge pier Radio frequency emitting devices number is 1, and a radio frequency reception device numbering is %1；Two radio frequency emitting devices of other side bridge pier are compiled It number is respectively 2,3, radio frequency reception device numbering is %2；The radio frequency emitting devices and radio frequency reception equipment of the same side are separated by Distance D_{1, %1}、D_{2, %2}And D_{3, %2}Meet the following conditions:

Wherein: c is the light velocity in vacuum.

4. high-precision bridge deformation detection method according to claim 1, it is characterised in that: radiofrequency signal is by numeric data code After golden code band spectrum modulation, modulated using carrier wave BPSK.

5. high-precision bridge deformation detection method according to claim 3, it is characterised in that: in step (3), it is assumed that radio frequency Emit the tranmitting frequency f of equipment j_i,(j)Frequency deviation Δ f has occurred_i,(j), radio frequency reception equipment k measures phase difference and is Then:

Wherein: c is the light velocity in vacuum, j=1,2,3, i=1,2, for radio frequency emitting devices 1, k=%1；Radio frequency is sent out Jet device 2 and 3, k=%2,It is the week whole fuzziness of measurement,For with frequency f_i,(j)+Δf_i,(j)The radio frequency of measurement Emit the distance between equipment j and radio frequency reception equipment k,For actual range；

Frequency deviation is calculated with following formula:

Wherein:Indicate actual frequency；

Since D is the value of a rice order of magnitude, it is far longer than the error amount of manual measurement, according to as defined in formula (4), (5) and (6) Condition is determined by the method for manual measurement And

6. high-precision bridge deformation detection method according to claim 5, it is characterised in that: two sides bridge pier in step (4) Radio frequency emitting devices j arrive respectively span centre measurement point radio frequency reception equipment m measured distance are as follows:

Wherein: For week whole fuzziness,For phase difference.

7. high-precision bridge deformation detection method according to claim 6, it is characterised in that: for frequency f2, Week whole fuzziness when surveying phaseObtained by the method for manual measurement, since measurement accuracy is different and WithThere are two types of relationships:

①At this time

SoTake the maximum value for meeting formula (11)；

②At this time

SoTake the minimum value for meeting formula (12)；

It determinesAfterwards, it is calculated by formula (10)

8. high-precision bridge deformation detection method according to claim 7, it is characterised in that: in step (5), penetrated known Take place frequently the coordinate (x of jet device j_j,y_j,z_j) under conditions of, the coordinate (x of radio frequency reception equipment m_m,y_m,z_m) can be true by following formula It is fixed: