CN102589410A - Phase sensitive detection type linear variable differential transformer (LVDT) displacement sensor for measuring pile foundation micro strain - Google Patents
Phase sensitive detection type linear variable differential transformer (LVDT) displacement sensor for measuring pile foundation micro strain Download PDFInfo
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- CN102589410A CN102589410A CN2012100672279A CN201210067227A CN102589410A CN 102589410 A CN102589410 A CN 102589410A CN 2012100672279 A CN2012100672279 A CN 2012100672279A CN 201210067227 A CN201210067227 A CN 201210067227A CN 102589410 A CN102589410 A CN 102589410A
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Abstract
The invention discloses a phase sensitive detection type linear variable differential transformer (LVDT) displacement sensor for measuring pile foundation micro strain, which comprises a fixed-amplitude oscillator, an LVDT displacement sensor, a phase sensitive detection device and a single chip microcomputer, wherein an output end of the fixed-amplitude oscillator is respectively connected with an input end of the LVDT displacement sensor and an input end of comparison signals of the phase sensitive detection device, an output end of detecting signals of the LVDT displacement sensor is connected with an input end of the phase sensitive detection device, a signal input end of the single chip microcomputer is connected with an output end of the phase sensitive detection device, a signal output end of the singe chip microcomputer is connected with outside equipments. According to the phase sensitive detection type LVDT displacement sensor for measuring pile foundation micro strain, the LVDT displacement sensor has an excellent common mode rejection capability and can hardly be affected by the temperature drift; the LVDT displacement sensor is applicable for bi-directional measuring and wide range occasions due to the utilization of a phase sensitive detection circuit; the displacement can be directly sent out, the secondary transformation calculation is not needed; the LVDT displacement sensor has extremely refined measurement resolution ratio and linearity.
Description
Technical field
The present invention relates to a kind of displacement transducer circuit; Relate in particular to a kind of phase sensitive detection type LVDT (Linear Variable Differential Transformer that is used to measure the pile foundation microstrain; The abbreviation of linear variable difference transformer is hereinafter to be referred as LVDT) displacement transducer.
Background technology
The traditional approach of in the building field pile foundation microstrain being measured is realized through adopting a kind of steel chord type strain gauge that is called.Its principle is: when on the string wire that two ends are tightened, imposing the excitation electric pulse, this string wire produces exciting; Suppose that this string wire is fixed in a certain rigid body cavity; Do the time spent deformation will take place when this rigid body receives external force, the deformation of rigid body will cause the distance between two fixed endpoints of built-in string wire that subtle change takes place, when string wire receives the electric pulse excitation; Exciting will take place in string wire; Corresponding variation also takes place in its oscillation frequency, through contrasting current mensuration frequency and last time measuring frequency, converses strain value according to experimental formula.
From the principle of summary, can clearly find out that the steel chord type strain gauge has following irremediable defective:
(1) because the two ends of string wire are tight, receive the tension force effect all the time, so nature deformation can take place in string wire, thereby cause the variation of its output natural frequency;
(2) consistance of steel chord type taseometer output signal is relatively poor, and the level of tightness of its output response and string wire, the consistance of string wire material are relevant, so each sensor needs independent correction;
(3) the steel chord type signal of sensor has tangible temperature drift characteristic;
(4) when the pile foundation strain measurement; Need tested reinforcing bar is blocked, the steel chord type sensor is welded between two fractures of reinforcing bar, therefore when pile foundation load; If the elastic modulus and the tested reinforcing bar of steel chord type sensor are inconsistent, then measured value is not had a meaning of guiding construction;
(5) measured value need pass through empirical parameter and carries out second Conversion, and precision is relatively poor, does not have comparability and consistance.
Summary of the invention
The objective of the invention is to overcome the defective of prior art and a kind of phase sensitive detection type LVDT displacement transducer that is used to measure the pile foundation microstrain is provided, this LVDT displacement transducer has the measuring accuracy height, receives characteristics such as temperature drift effects hardly.
The objective of the invention is to realize like this:
A kind of phase sensitive detection type LVDT displacement transducer that is used to measure the pile foundation microstrain of the present invention; It comprises amplitude stabilizer oscillator, LVDT displacement transducer, phase-sensitive detector (PSD) and single-chip microcomputer; The output terminal of said amplitude stabilizer oscillator links to each other with the pumping signal input end of said LVDT displacement transducer and the comparison signal input end of said phase-sensitive detector (PSD) respectively; The detection signal output terminal of said LVDT displacement transducer links to each other with the input end of said phase-sensitive detector (PSD); The signal input part of said single-chip microcomputer links to each other with the output terminal of said phase-sensitive detector (PSD), and the signal output part of said single-chip microcomputer links to each other with external unit; Wherein:
Said amplitude stabilizer oscillator produces and exports the sine wave exciting signal of fixed ampllitude;
Said LVDT displacement transducer receives the sine wave exciting signal of said amplitude stabilizer oscillator output, detects the back output detection signal;
Said phase-sensitive detector (PSD) receives the detection signal of said LVDT displacement transducer output, and it is made phase sensitive detection handle, the output two-dimensional information signal;
Said single-chip microcomputer receives the two-dimensional information signal of said phase-sensitive detector (PSD) output, and this signal is carried out digitized processing, outwards exports digital signal with the RS232 mode.
Above-mentioned a kind of phase sensitive detection type LVDT displacement transducer that is used to measure the pile foundation microstrain, wherein, the digital signal of said single-chip microcomputer output is 12 position digital signals.
Displacement transducer of the present invention compared with prior art has the following advantages:
1. the LVDT displacement transducer of the present invention's employing has quite good common mode inhibition capacity; For example temperature variation class parameter is converted into the common mode amount in the output response of displacement transducer of the present invention; Therefore for this common mode measurer of temperature variation good inhibition ability is arranged, can receive the influence of temperature drift hardly;
2. owing to having adopted phase-sensitive detection circuit, applicable to the wide range occasion of bidirectional measurement;
3. direct output shift quantity need not twice transformation and calculates;
4. have the extremely meticulous Measurement Resolution and the linearity.
Description of drawings
Fig. 1 is the theory diagram of LVDT displacement transducer of the present invention;
Fig. 2 is the circuit structure diagram of LVDT displacement transducer of the present invention;
Fig. 3 is the circuit structure diagram of phase-sensitive detector (PSD) among the present invention.
Embodiment
To combine accompanying drawing that the present invention is described further below.
See also Fig. 1; The theory structure that the present invention is used to measure the phase sensitive detection type LVDT displacement transducer of pile foundation microstrain has been shown among the figure; It comprises amplitude stabilizer oscillator 1, LVDT displacement transducer 2, phase-sensitive detector (PSD) 3 and single-chip microcomputer 4; The output terminal of amplitude stabilizer oscillator 1 links to each other with the pumping signal input end of LVDT displacement transducer 2 and the comparison signal input end of phase-sensitive detector (PSD) 3 respectively; The detection signal output terminal of LVDT displacement transducer 2 links to each other with the input end of phase-sensitive detector (PSD) 3, and the signal input part of single-chip microcomputer 4 links to each other with the output terminal of phase-sensitive detector (PSD) 3, and the signal output part of single-chip microcomputer 4 links to each other with external unit.
Wherein, the model of single-chip microcomputer 4 is 12 CC2530.
See also Fig. 2, the circuit structure that the present invention is used to measure the phase sensitive detection type LVDT displacement transducer of pile foundation microstrain has been shown among the figure.2.5KHz amplitude stabilizer oscillator 1 by integrated operational amplifier IC1:A (TL082) and electric capacity constitute is started working; The sine wave of output forms the sine wave exciting signal of 3 volts (effective values) after integrated operational amplifier IC1:B (TL082) amplifies, export LVDT displacement transducer 2 (in order to the primary coil of excitation LVDT displacement transducer 2) and phase-sensitive detector (PSD) 3 (being used for as comparison signal) respectively to.The detection signal of LVDT displacement transducer 2 outputs is exported a signal that comprises amplitude Characteristics and sense of displacement after being carried out the phase sensitive detection processing by phase-sensitive detector (PSD) 3, is fed to the signal input part port of single-chip microcomputer 4 (CC2530).Simultaneously, energising back single-chip microcomputer 4 (CC2530) was started working, through 2 seconds time-delay post-sampling voltage signals; The purpose of implementing time-delay in 2 seconds is wait for amplitude stabilizer oscillator 1 output signal stable.12 position digital signals after single-chip microcomputer 4 (CC2530) digitized processing are exported with the RS232 mode.Reference source IC 8 (REF3020) provides voltage reference for the AD conversion of single-chip microcomputer 4.
The circuit structure of above-mentioned phase-sensitive detector (PSD) 3 is as shown in Figure 3; The operational amplifier OPA221 that wherein adopts is that a ultra-low noise, band are forbidden the low price high-performance amplifier of holding, and it forbids that end (Pin 8) goes up when inserting positive level; Device output is high resistant, and output is closed; When forbidding that end (Pin 8) is gone up the access zero level, output is enabled.
See also Fig. 3, the principle of phase-sensitive detector (PSD) 3 is following: the armature of LVDT displacement transducer 2 leaves initial point and prolongs axially and depart from left, then exports signal SIG and OSC homophase (for just).When the former limit at LVDT displacement transducer 2 adds the fixed ampllitude sine wave exciting signal OSC of 2.5KHz; Upper half at sine wave exciting signal; Comparer IC1:A (LM339) output DIS2 is a high level, and comparer IC1:B (LM339) output DIS1 is a low level, therefore; The output of IC3 (OPA211) inverting amplifier is under an embargo; The output of IC2 (OPA211) in-phase amplifier is enabled, since the input signal and the pumping signal OSC homophase of IC3 (OPA211) end of oppisite phase and IC2 (OPA211) homophase, sinusoidal wave first wave envelope of IC2 (OPA211) output cathode property; When the sine wave exciting signal zero passage gets into lower half; Comparer IC1:A (LM339) output DIS2 is a low level; Comparer IC1:B (LM339) output DIS1 is a high level, and therefore, the output of IC3 (OPA211) inverting amplifier is enabled; The output of IC2 (OPA211) in-phase amplifier is under an embargo, the sinusoidal wave envelope of IC3 (OPA211) output cathode property lower half; The output of synthetic IC2 (OPA211) and IC3 (OPA211) obtains the positive polarity sine wave envelope of similar full-wave rectification.
Prolong when axially departing to the right when the armature of LVDT displacement transducer 2 among Fig. 3 leaves initial point, then export signal SIG and OSC anti-phase.Upper half at sine wave exciting signal; Comparer IC1:A (LM339) output DIS2 is a high level, and comparer IC1:B (LM339) output DIS1 is a low level, therefore; The output of IC3 (OPA211) inverting amplifier is under an embargo; The output of IC2 (OPA211) in-phase amplifier is enabled, since the input signal and the pumping signal OSC anti-phase of IC3 (OPA211) end of oppisite phase and IC2 (OPA211) homophase, the sinusoidal wave half-wave envelope of IC2 (OPA211) output negative pole property; When the sine wave exciting signal zero passage gets into lower half; Comparer IC1:A (LM339) output DIS2 is a low level; Comparer IC1:B (LM339) output DIS1 is a high level, and therefore, the output of IC3 (OPA211) inverting amplifier is enabled; The output of IC2 (OPA211) in-phase amplifier is under an embargo, the sinusoidal wave envelope of IC3 (OPA211) output negative pole property lower half; The output of synthetic IC2 (OPA211) and IC3 (OPA211) obtains the negative polarity sine wave envelope of similar full-wave rectification.Resistance R 8 in Fig. 3 circuit, R14 constitute the output smoothing network of IC2 (OPA211) and IC3 (OPA211) respectively with electric capacity E1, get about 3 times time constant of driving source osc signal cycle; Certainly, can get bigger time constant, because be used for the strain measurement of pile foundation reinforcing bar, the dependent variable of reinforcing bar is individual variable very slowly.
Above embodiment only supplies to explain the present invention's usefulness; But not limitation of the present invention; The technician in relevant technologies field under the situation that does not break away from the spirit and scope of the present invention, can also make various conversion or modification; Therefore all technical schemes that are equal to also should belong to category of the present invention, should be limited each claim.
Claims (2)
1. phase sensitive detection type LVDT displacement transducer that is used to measure the pile foundation microstrain; It is characterized in that; It comprises amplitude stabilizer oscillator, LVDT displacement transducer, phase-sensitive detector (PSD) and single-chip microcomputer; The output terminal of said amplitude stabilizer oscillator links to each other with the pumping signal input end of said LVDT displacement transducer and the comparison signal input end of said phase-sensitive detector (PSD) respectively; The detection signal output terminal of said LVDT displacement transducer links to each other with the input end of said phase-sensitive detector (PSD), and the signal input part of said single-chip microcomputer links to each other with the output terminal of said phase-sensitive detector (PSD), and the signal output part of said single-chip microcomputer links to each other with external unit; Wherein:
Said amplitude stabilizer oscillator produces and exports the sine wave exciting signal of fixed ampllitude;
Said LVDT displacement transducer receives the sine wave exciting signal of said amplitude stabilizer oscillator output, detects the back output detection signal;
Said phase-sensitive detector (PSD) receives the detection signal of said LVDT displacement transducer output, and it is made phase sensitive detection handle, the output two-dimensional information signal;
Said single-chip microcomputer receives the two-dimensional information signal of said phase-sensitive detector (PSD) output, and this signal is carried out digitized processing, outwards exports digital signal with the RS232 mode.
2. a kind of phase sensitive detection type LVDT displacement transducer that is used to measure the pile foundation microstrain as claimed in claim 1 is characterized in that, the digital signal of said single-chip microcomputer output is 12 position digital signals.
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| CN2012100672279A CN102589410A (en) | 2012-03-15 | 2012-03-15 | Phase sensitive detection type linear variable differential transformer (LVDT) displacement sensor for measuring pile foundation micro strain |
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| CN2012100672279A CN102589410A (en) | 2012-03-15 | 2012-03-15 | Phase sensitive detection type linear variable differential transformer (LVDT) displacement sensor for measuring pile foundation micro strain |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103292679A (en) * | 2013-05-24 | 2013-09-11 | 江阴市江凌科技有限公司 | Displacement measuring circuit |
| CN104019833A (en) * | 2014-06-13 | 2014-09-03 | 四川亚美动力技术有限公司 | Engine oil pin position sensor detecting circuit |
| CN109238121A (en) * | 2018-11-09 | 2019-01-18 | 美钻深海能源科技研发（上海）有限公司 | A kind of underwater kit ohject displacement data detection system and its method |
| CN110132118A (en) * | 2019-06-13 | 2019-08-16 | 重庆红江机械有限责任公司 | A kind of displacement detection system based on LVDT sensor |
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| CN201909972U (en) * | 2010-11-10 | 2011-07-27 | 南京因泰莱配电自动化设备有限公司 | Long-term online monitoring device for mechanical properties of high-voltage circuit breaker |
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2012
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| EP0721563B1 (en) * | 1993-10-01 | 2000-06-28 | THE GOVERNMENT OF THE UNITED STATES OF AMERICA, as represented by THE SECRETARY OF THE NAVY | Magnetoresistive linear displacement sensor, angular displacement sensor, and variable resistor |
| US5708368A (en) * | 1996-03-07 | 1998-01-13 | Ade Corporation | Method and apparatus for emulation of a linear variable differential transducer by a capacitive gaging system |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103292679A (en) * | 2013-05-24 | 2013-09-11 | 江阴市江凌科技有限公司 | Displacement measuring circuit |
| CN103292679B (en) * | 2013-05-24 | 2015-09-30 | 江阴市江凌科技有限公司 | Displacement measurement circuit |
| CN104019833A (en) * | 2014-06-13 | 2014-09-03 | 四川亚美动力技术有限公司 | Engine oil pin position sensor detecting circuit |
| CN104019833B (en) * | 2014-06-13 | 2016-06-08 | 四川亚美动力技术有限公司 | Engine oil needle position sensor detection circuit |
| CN109238121A (en) * | 2018-11-09 | 2019-01-18 | 美钻深海能源科技研发（上海）有限公司 | A kind of underwater kit ohject displacement data detection system and its method |
| CN110132118A (en) * | 2019-06-13 | 2019-08-16 | 重庆红江机械有限责任公司 | A kind of displacement detection system based on LVDT sensor |
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Application publication date: 20120718 |