CN102374896A - Method and device for measuring equal precision frequency of single coil vibrating wire instrument - Google Patents
Method and device for measuring equal precision frequency of single coil vibrating wire instrument Download PDFInfo
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- CN102374896A CN102374896A CN 201110277519 CN201110277519A CN102374896A CN 102374896 A CN102374896 A CN 102374896A CN 201110277519 CN201110277519 CN 201110277519 CN 201110277519 A CN201110277519 A CN 201110277519A CN 102374896 A CN102374896 A CN 102374896A
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Abstract
The invention relates to a method and device for measuring the equal precision frequency of a single coil vibrating wire instrument. The method comprises the following steps of: generating induced voltage signals having frequencies accordant with the natural frequency of a string wire and attenuated amplitudes at the two ends of the frequency measuring coil; monitoring the amplitude attenuating conditions of the induced voltage signals through an induced voltage attenuating monitoring circuit; when the monitored amplitude attenuating speeds of the induced voltage signals are up to a preset value, providing a triggering signal for an equal precision frequency measuring circuit; adjusting the measuring time of the equal precision frequency measuring circuit by adjusting a standard reference pulse frequency through the precision frequency measuring circuit; and calculating the frequency of the string wire by using the equal precision frequency measuring circuit according to the induced voltage pulse sample number obtained by counting and the count value of a set standard reference pulse frequency counter. In the method, the lasting time of the measuring process can be adjusted adaptively according to the monitored amplitude attenuating conditions of the induced voltage signals activated by the string wire, so that the equal precision frequency measuring reliability of the single coil vibrating wire instrument is improved.
Description
Technical field
The present invention relates to Geotechnical Engineering health monitoring technical field, the unicoil type vibration wire instrument in particularly a kind of Geotechnical Engineering safety monitoring instrument etc. the frequency measurement with constant-precision method and apparatus.
Background technology
In safety monitoring, adopt the physical quantitys such as ess-strain, temperature, seam aperture, seepage and distortion of safety monitoring instrument monitoring Geotechnical Engineerings such as type vibration wire (or claiming steel chord type) instrument usually, in order to the safety of analysis and judgement Geotechnical Engineering to Geotechnical Engineering.
Type vibration wire instrument (or claim vibrating string type sensor) by two ends fix, the string wire of homogeneous forms.String wire length is L, and in perception external influence power F (can be ess-strain, temperature, seam aperture, seepage and the distortion etc. of Geotechnical Engineering), string wire can produce the stretcher strain of Δ L, in elastic range, and the influence of account temperature T simultaneously,
Δ T=T-T wherein
0, α is a linear expansion coefficient, T
0, α, K be known constant number.The mechanical vibration natural frequency f of string wire can obtain by following formula:
Wherein E is the elastic modulus of string wire, ρ
vBe the density of string wire, λ is the Poisson's coefficient of string wire material, and these are permanent number.Above-mentioned two formula are put in order; Eliminate
this common variable; Drawing F is definite function of f and T, just can realize the measurement of F through measurement f and T.Wherein, frequency parameter f is the most key measurement factor.
In the type vibration wire instrument that use in the safety monitoring field at present; Have various ways such as twin coil type vibration wire instrument, unicoil type vibration wire instrument, differential winding type vibration wire instrument according to the loop construction type, wherein unicoil type vibration wire instrument all has comparative advantage in many-sides such as kind, range of application, quantity.Fig. 1 is a unicoil type vibration wire apparatus structure synoptic diagram; String wire 1 is arranged in the magnetic field of frequency measurement coil 2 and permanent magnet 3 formations; Through apply the exciting current signal of alternation to frequency measurement coil 2 two ends in the unicoil type vibration wire instrument; Under the effect of permanent magnet 3, form alternating electromagnetic force, drive string wire 1 mechanical vibration take place, the string wire 1 of vibration is made cutting magnetic line movement in magnetic field; In frequency measurement coil 2, induce electromotive force, the frequency of induction electromotive force is the vibration frequency of string wire 1.Traditional frequency measurement method adopts the frequency counting method, and promptly the later frequency measurement circuit of exciting adopts counter to measure the induced potential recurrence interval, can record the vibration frequency of string wire 1, and this method principle simple, intuitive is feasible, is used widely.But in practice,, particularly wait the frequency measurement with constant-precision method through the method survey frequency of frequency counting; To different original frequencies; Precision such as the measurement of each frequency all guarantees, so will obtain certain definition and measuring accuracy, measuring process needs abundant induced potential impulse smaple; That is to say that the measuring process of frequency need continue the regular hour.
It is documented and test findings; String wire is after the exciting current signal is cancelled; The duration that produces induction electromotive force owing to the string wire cutting magnetic line is generally between 800ms～60ms; That is to say that behind each exciting, follow-up frequency measurement circuit is used for the time of frequency measurement should be accomplished between 800ms～60ms.Precision frequency measuring method such as existing; Be direct frequency measurement through precision such as frequency measurement circuit carry out, the time that its frequency measurement process need continues is predefined, regardless of unicoil type vibration wire instrument running status of living in; All measure according to predefined Measuring Time; Can't dynamic adjustments, and unicoil type vibration wire instrument is in the different operation phase, the duration that behind exciting, produces induced electromotive force exists than big-difference; Such as when vibrational waveform is significantly decayed suddenly; Make that the impulse smaple number of induced potential is not enough, will cause frequency measurement circuit not detect number or the inaccurate situation of measured value, finally cause the decline of the doomed dead and reliable measurement property of unicoil type vibration wire instrument; And the safety monitoring of Geotechnical Engineering has strict requirement to the reliability of safety monitoring assembly and measuring accuracy; This just requires on measuring principle and measuring method, to make every effort to accurately and reliably, therefore need to introduce more technological than the more reliable frequency measurement of frequency measurement with constant-precision method such as traditional, with the high precision that satisfies unicoil type vibration wire instrument and the measurement requirement of high reliability.
Summary of the invention
The present invention is directed to existing unicoil type vibration wire instrument etc. the unicoil type vibration wire instrument in the frequency measurement with constant-precision method in the different operation phase; The duration that behind exciting, produces induced electromotive force exists than big-difference; Cause accomplishing the problem of measuring or reducing measuring accuracy, proposed a kind of unicoil type vibration wire instrument etc. the frequency measurement with constant-precision method, this method is still based on the count measurement frequency; Can be according to the amplitude attenuation situation of the induced potential behind the string wire exciting that monitors; Regulate the duration of measuring process adaptively, and keep identical measuring accuracy, improved unicoil type vibration wire instrument frequency measuring reliability.The invention still further relates to a kind of unicoil type vibration wire instrument etc. the frequency measurement with constant-precision device.
Technical scheme of the present invention is following:
A kind of unicoil type vibration wire instrument etc. the frequency measurement with constant-precision method; At first make frequency measurement coil two ends generate and string wire natural frequency induced potential signal consistent, amplitude attenuation through the string wire exciting; The count value of frequency measurement with constant-precision circuit according to the canonical reference pulsed frequency counting device of induced potential impulse smaple number that counts to get and setting such as pass through then; Calculate the frequency of string wire; It is characterized in that, after frequency measurement coil two ends generate said induced potential signal, also pass through the amplitude attenuation situation of induced potential decay monitoring circuit monitors induced potential signal; And in the amplitude attenuation speed that monitors the induced potential signal during to predetermined value; To etc. the frequency measurement with constant-precision circuit trigger pip is provided, the trigger pip that frequency measurement with constant-precision circuit such as said provides according to induced potential decay observation circuit, the canonical reference pulsed frequency in the frequency measurement with constant-precision circuit such as adjustment such as adjust at the Measuring Time of frequency measurement with constant-precision circuit.
Frequency measurement with constant-precision circuit such as main and frequency measurement with constant-precision such as frequency measurement with constant-precision circuit such as auxiliary carries out are set in waiting frequency measurement with constant-precision circuit; Primary standard reference pulse frequency in the frequency measurement with constant-precision circuit such as said master is less than the auxiliary criteria reference pulse frequency in the frequency measurement with constant-precision circuit such as auxiliary; When induced potential is decayed observation circuit when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value, through of the adjustment of frequency measurement with constant-precision circuit such as master to the Measuring Time of the frequency measurement with constant-precision circuit such as switching realization of frequency measurement with constant-precision circuit such as assisting.
Said induced potential decay monitoring circuit monitors to the induced potential decay just often; The count value of the primary standard reference pulse frequency counter that obtains through frequency measurement with constant-precision circuit count such as main being provided with in impulse smaple number and the frequency measurement with constant-precision circuit such as main of induced potential calculates the frequency of string wire; Said induced potential decay observation circuit is when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value; To frequency measurement with constant-precision circuit such as auxiliary trigger pip is provided; After receiving trigger pip, frequency measurement with constant-precision circuit such as auxiliary starts; And, calculate the frequency of string wire according to the count value of the auxiliary criteria reference pulse frequency counter that is provided with in the impulse smaple number of the induced potential that counts to get and the frequency measurement with constant-precision circuit such as auxiliary.
After frequency measurement coil two ends generate said induced potential; Earlier the induced potential signal is amplified; The attenuation of the induced potential after amplifying through induced potential decay monitoring circuit monitors is again carried out the induced potential signal that amplifies after the shaping frequency measurement with constant-precision circuit such as input more simultaneously.
Realize by of the switching of frequency measurement with constant-precision circuit such as master through logic control circuit to frequency measurement with constant-precision circuit such as assisting; And induced potential impulse smaple number that frequency measurement with constant-precision circuit and frequency measurement with constant-precision circuit count such as auxiliary obtain such as will lead and the count value of each frequency counter is read in microcontroller, calculate the frequency of string wire by microcontroller.
A kind of unicoil type vibration wire instrument etc. the frequency measurement with constant-precision device; Comprise exciting device, on-off circuit and etc. the frequency measurement with constant-precision circuit, said on-off circuit at times with exciting device with etc. the frequency measurement with constant-precision circuit respectively with unicoil type vibration wire instrument in the frequency measurement coil link to each other; Saidly be meant at times: on-off circuit is communicated with exciting device and frequency measurement coil earlier, and exciting device applies the frequency sweep accumulation signal of alternation at frequency measurement coil two ends, formation alternating electromagnetic force under the effect of permanent magnet, driving string wire generation mechanical vibration; On-off circuit cuts off being connected between exciting device and the frequency measurement coil again, and the mechanical vibration of string wire form the standing wave of single-frequency, and frequency measurement coil two ends form and string wire mechanical vibration frequency induced potential signal consistent, amplitude attenuation; On-off circuit be communicated with again the frequency measurement coil with etc. the frequency measurement with constant-precision circuit; Frequency measurement with constant-precision circuit such as said is according to the count value of the canonical reference pulsed frequency counting device of induced potential impulse smaple number that counts to get and setting; Calculate the frequency of string wire; It is characterized in that; Also comprise induced potential decay observation circuit, said induced potential decay observation circuit with etc. the frequency measurement with constant-precision circuit link to each other the amplitude attenuation situation of the induced potential signal of induced potential decay monitoring circuit monitors frequency measurement coil two ends generation; And when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value; To etc. the frequency measurement with constant-precision circuit trigger pip is provided, the trigger pip that frequency measurement with constant-precision circuit such as said also provides according to induced potential decay observation circuit, the canonical reference pulsed frequency in the frequency measurement with constant-precision circuit such as adjustment such as adjust at the Measuring Time of frequency measurement with constant-precision circuit.
Frequency measurement with constant-precision circuit such as said comprises frequency measurement with constant-precision circuit such as main, frequency measurement with constant-precision circuit, logic control circuit and microcontroller such as auxiliary; Said logic control circuit links to each other with microcontroller with induced potential decay observation circuit respectively; Frequency measurement with constant-precision circuit such as said master comprise main frequency counter to be measured and primary standard reference pulse frequency counter; Said frequency measurement with constant-precision circuit such as auxiliary comprises auxiliary frequency counter to be measured and auxiliary criteria reference pulse frequency counter; Said primary standard reference pulse frequency is less than auxiliary criteria reference pulse frequency; After said logic control circuit receives the trigger pip of induced potential decay observation circuit, through controlling the adjustment of frequency measurement with constant-precision circuit such as main to the Measuring Time of the frequency measurement with constant-precision circuit such as switching realization of frequency measurement with constant-precision circuit such as auxiliary.
Also comprise amplifying circuit and shaping circuit; Said on-off circuit links to each other with induced potential decay observation circuit through amplifying circuit; Said on-off circuit successively through amplifying circuit and shaping circuit with etc. the frequency measurement with constant-precision circuit link to each other; Input to induced potential decay observation circuit after the induced potential that said amplifying circuit generates frequency measurement coil two ends amplifies again and monitor, said shaping circuit carries out the induced potential signal that amplifies after the shaping frequency measurement with constant-precision circuit such as input again.
Said logic control circuit is FPGA or CPLD.
Said induced potential decay observation circuit comprises precise rectification circuit, filtering circuit and the voltage comparator circuit that connects successively, and said precise rectification circuit links to each other with amplifying circuit, and voltage comparator circuit links to each other with logic control circuit.
Technique effect of the present invention is following:
The unicoil type vibration wire instrument that the present invention relates to etc. the frequency measurement with constant-precision method; Behind the string wire exciting, make frequency measurement coil two ends form and string wire mechanical vibration frequency induced potential signal consistent, amplitude attenuation; Amplitude attenuation situation through this induced potential signal of induced potential decay monitoring circuit monitors; And (the amplitude attenuation amount in the unit interval reaches predefined degree when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value; Show that amplitude attenuation is too fast); To etc. the frequency measurement with constant-precision circuit trigger pip is provided; The Measuring Time of frequency measurement with constant-precision circuit such as adjust etc. frequency measurement with constant-precision circuit adjustment canonical reference pulsed frequency in it, wait the count value of frequency measurement with constant-precision circuit at last, calculate the frequency of string wire according to induced potential impulse smaple number that counts to get and adjusted canonical reference pulsed frequency counting device.This measuring method can be known the duty of the different operation phase of tested unicoil type vibration wire instrument through the monitoring to the amplitude attenuation situation of induced potential signal, when monitoring induced potential signal attenuation relatively slowly the time; Estimate that the induced potential signal can continue the long period; Etc. the normal frequency measurement of frequency measurement with constant-precision circuit, when monitoring induced potential signal attenuation relatively rapidly the time, induced potential decay observation circuit triggers; To etc. the frequency measurement with constant-precision circuit trigger pip is provided; According to the amplitude attenuation situation of the induced potential signal of monitoring, the canonical reference pulsed frequency in the precision frequencies such as change in time dynamically changes the strategy of frequency measurement with the Measuring Time of frequency measurement with constant-precision circuit such as adjustment; Optimized the frequency measurement time; Accomplish equal precision measurement, avoided frequency measurement with constant-precision circuit such as existing to measure, when induced potential signal attenuation is too fast, cause to accomplish the problem of measuring or reducing measuring accuracy according to predetermined Measuring Time; Improve the reliability of frequency measurement, and guaranteed the precision of frequency measurement.
Frequency measurement with constant-precision circuit such as main and frequency measurement with constant-precision such as frequency measurement with constant-precision circuit such as auxiliary carries out are set; Canonical reference pulsed frequency in two circuit is different; Induced potential decay observation circuit is monitoring the induced potential rate of decay when reaching predetermined value; Through of adjustment and the optimization of frequency measurement with constant-precision circuit such as master to the Measuring Time of the frequency measurement with constant-precision circuit such as switching realization of frequency measurement with constant-precision circuit such as assisting, this measuring method simple possible, operation easily.
The unicoil type vibration wire instrument that the present invention relates to etc. the frequency measurement with constant-precision device; Through be provided with etc. the induced potential that links to each other of the frequency measurement with constant-precision circuit observation circuit of decaying; The amplitude attenuation situation of can monitoring frequency measuring the induced potential signal that the coil two ends generate; And when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value (the amplitude attenuation amount in the unit interval reaches predefined degree, shows that amplitude attenuation is too fast), trigger pip is provided to frequency measurement with constant-precision circuit such as follow-up; After receiving trigger pip etc. the frequency measurement with constant-precision circuit; The canonical reference pulsed frequency of adjusting self such as adjusts at the Measuring Time of frequency measurement with constant-precision circuit, this Measuring Time is optimized, according to the residing different conditions of unicoil type vibration wire instrument; Its frequency measurement time of dynamic adjustments; To guarantee from the induced potential signal, obtaining enough induced potential impulse smaple numbers, realize the frequency measurement with constant-precision such as self-adaptation of unicoil type vibration wire instrument, improved the reliability of frequency measurement.
Induced potential decay observation circuit is set comprises precise rectification circuit, filtering circuit and the voltage comparator circuit that connects successively, said precise rectification circuit links to each other with amplifying circuit, and voltage comparator circuit links to each other with logic control circuit.After the induced potential signal of the amplitude attenuation at frequency measurement coil two ends amplifies like this; Be converted into the average voltage amplitude of the reflection induced potential signal amplitude attenuation of direct current through precise rectification circuit; With getting into voltage comparator circuit and predefined normal voltage after its filtering more relatively; Draw the monitoring of the attenuation amplitude of induced potential signal; Through the qualitative analysis to the amplitude attenuation situation of induced potential signal, whether decision provides trigger pip to logic control circuit, further determine whether by etc. frequency measurement with constant-precision circuit adjustment and optimize Measuring Time to realize precision frequency such as adaptive measuring.Duty to different operation phase of unicoil type vibration wire instrument has good adaptive faculty, and the safety monitoring that can satisfy Geotechnical Engineering is to the reliability of safety monitoring instrument and the requirement that guarantees measuring accuracy.
Description of drawings
Fig. 1 is a unicoil type vibration wire apparatus structure synoptic diagram.
Fig. 2 for unicoil type vibration wire instrument of the present invention etc. the preferred structure synoptic diagram of frequency measurement with constant-precision device.
Fig. 3 is the slow induced potential signal waveforms of amplitude fading that the frequency measurement coil produces behind the exciting.
Fig. 4 is the fast induced potential signal waveforms of amplitude fading that the frequency measurement coil produces behind the exciting.
Fig. 5 is the preferred structure block diagram of induced potential decay observation circuit.
Fig. 6 such as is at the preferred structure block diagram of frequency measurement with constant-precision circuit.
Fig. 7 for unicoil type vibration wire instrument of the present invention etc. the preferred flow charts of frequency measurement with constant-precision method.
Each label is listed as follows among the figure:
The 1-string wire; 2-frequency measurement coil; The 3-permanent magnet; Frequency measurement with constant-precision circuit such as 4-; Frequency measurement with constant-precision circuit such as 5-master; Frequency measurement with constant-precision circuit such as 6-is auxiliary.
Embodiment
The present invention will be described below in conjunction with accompanying drawing.
Fig. 2 for unicoil type vibration wire instrument of the present invention etc. the preferred structure synoptic diagram of frequency measurement with constant-precision device.This device comprise exciting device, on-off circuit, amplifying circuit, shaping circuit, induced potential decay observation circuit and etc. frequency measurement with constant-precision circuit 4; Wherein, Exciting device comprises signal generator, on-off circuit at times with signal generator and amplifying circuit respectively with unicoil type vibration wire instrument in the frequency measurement coil link to each other.Be specially the line select switch circuit of on-off circuit at times as exciting and pick-up; When on-off circuit elder generation's communications signals generator and frequency measurement coil; The A of frequency measurement coil 2, B two ends are connected to the output terminal of signal generator; Signal generator applies the frequency sweep accumulation signal of alternation at the two ends of frequency measurement coil, under the effect of permanent magnet, form alternating electromagnetic force, drives string wire 1 mechanical vibration take place; On-off circuit is being connected between shutoff signal generator and the frequency measurement coil 2 again; The mechanical vibration of string wire 1 form the standing wave of single-frequency; Frequency measurement coil 2 two ends form and string wire 1 mechanical vibration frequency induced potential signal consistent, amplitude attenuation, slow induced potential signal waveforms and the fast induced potential signal waveforms of amplitude fading of amplitude fading shown in Fig. 3 and Fig. 4 difference; After getting in touch between on-off circuit shutoff signal generator and the frequency measurement coil 2, can be communicated with frequency measurement coil 2 and amplifying circuit, be about to the A of frequency measurement coil 2, the input end that the B two ends are connected to amplifying circuit; Amplifying circuit amplifies faint induced potential signal.The output terminal of amplifying circuit be connected with in turn shaping circuit with etc. the frequency measurement with constant-precision circuit; The output terminal of amplifying circuit also connects the input end of induced potential decay observation circuit simultaneously, the input end of the frequency measurement with constant-precision circuit 4 such as output terminal connection of induced potential decay observation circuit.
The preferred structure block diagram of induced potential decay observation circuit is as shown in Figure 5, comprises the precise rectification circuit, filtering circuit and the voltage comparator circuit that connect successively.Precise rectification circuit links to each other with amplifying circuit; Voltage comparator circuit with etc. the frequency measurement with constant-precision circuit link to each other; Induced potential signal through amplifying carries out AC-DC conversion through precise rectification circuit; Be converted into the average voltage amplitude of amplitude attenuation situation of the reflection induced potential signal of direct current; The average effect of the amplitude attenuation situation of its waveform reaction induced potential signal; Carry out inputing to voltage comparator circuit after the filtering through filtering circuit, in voltage comparator circuit, preestablished normal voltage, predefined normal voltage in the average voltage amplitude of the amplitude attenuation situation of reflection induced potential signal and the voltage comparator circuit is compared; This normal voltage can be arranged between 2～4V according to experiment value; The fast induced potential signal waveform of amplitude fading shown in Figure 4 is forced down than the standard electric of being scheduled to through the average voltage amplitude behind precise rectification circuit and the filtering circuit, to etc. the frequency measurement with constant-precision circuit trigger pip is provided, after the frequency measurement with constant-precision circuit receives trigger pip; Adjust the Measuring Time of the canonical reference pulsed frequency of self with frequency measurement with constant-precision circuit such as adjustment; This Measuring Time is optimized,, calculates the frequency of string wire etc. the count value of the canonical reference pulsed frequency counting device of frequency measurement with constant-precision circuit after according to the adjustment canonical reference pulsed frequency of the induced potential impulse smaple number that counts to get and setting; And slow induced potential signal waveform process precise rectification circuit and the predetermined normal voltage height of the average voltage amplitude ratio behind the filtering circuit of amplitude fading as shown in Figure 3; This moment not to etc. the frequency measurement with constant-precision circuit trigger pip is provided; Still measure according to original canonical reference pulsed frequency and original Measuring Time etc. the frequency measurement with constant-precision circuit; Etc. the count value of frequency measurement with constant-precision circuit, calculate the frequency of string wire according to the canonical reference pulsed frequency counting device of induced potential impulse smaple number that counts to get and setting.
Induced potential decay observation circuit shown in Figure 5 can be accomplished the qualitative analysis to the amplitude attenuation situation of induced potential signal; When the induced potential amplitude attenuation amount in the unit interval reaches predefined degree (predefined normal voltage is associated in this predefined degree and the voltage comparator circuit); Show that this amplitude attenuation is too fast; Then induced potential decay observation circuit to etc. the frequency measurement with constant-precision circuit trigger pip is provided; Except this structure, can also select devices such as sample circuit and A/D convertor circuit that the amplitude attenuation situation of induced potential signal is carried out quantitative test, again decision whether to etc. the frequency measurement with constant-precision circuit trigger pip is provided.
Preferred structure block diagram etc. frequency measurement with constant-precision circuit 4 is as shown in Figure 6; Comprise frequency measurement with constant-precision circuit 5 such as main, frequency measurement with constant-precision circuit 6, logic control circuit and microcontroller (to call MCU in the following text) such as auxiliary; Wherein, Frequency measurement with constant-precision circuit 5 such as master comprise that leading frequency counter to be measured, primary standard reference pulse frequency counter and analytic accounting counts sync logic; Analytic accounting is counted sync logic and is connected main frequency counter to be measured and primary standard reference pulse frequency counter respectively; Frequency measurement with constant-precision circuit 6 such as auxiliary comprises that auxiliary frequency counter to be measured, auxiliary criteria reference pulse frequency counter and auxiliary counting sync logic, auxiliary counting sync logic connect auxiliary frequency counter to be measured and auxiliary criteria reference pulse frequency counter respectively, like this; Etc. having two-way canonical reference pulse signal in the frequency measurement with constant-precision circuit, primary standard reference pulse frequency is less than auxiliary criteria reference pulse frequency; Logic control circuit comprises first logic control circuit and second logic control circuit; The input end of said first logic control circuit links to each other with induced potential decay observation circuit; Output terminal all connects analytic accounting and counts sync logic and auxiliary counting sync logic; Main frequency counter to be measured, primary standard reference pulse frequency counter, auxiliary frequency counter to be measured all are connected second logic control circuit with auxiliary criteria reference pulse frequency counter, and first logic control circuit all is connected MCU with second logic control circuit.
Suppose that the induced potential signal frequency treats that promptly measured frequency is Fx; Main frequency counter to be measured and auxiliary frequency counter to be measured all receive the counting that the induced potential signal that amplifies after the shaping is treated measured frequency Fx; Primary standard reference pulse frequency is F0; Auxiliary criteria reference pulse frequency is F0 ', F0＜F0 '.Logic control circuit (comprising first logic control circuit and second logic control circuit) can adopt FPGA (Field Programmable Gate Array; Field programmable gate array) or CPLD (Complex Programmable Logic Device, CPLD) realize.The induced potential signal of one tunnel amplification generates the square wave of same frequency behind shaping circuit; Get into frequency measurement with constant-precision circuit such as main; Carry out regular situation (being that the induced potential signal is decayed according to normal attenuation amplitude) etc. frequency measurement with constant-precision; The induced potential signal that amplify on another road gets into induced potential decay observation circuit, when generation is unusual (decay of induced potential signal amplitude is too fast), just produces the trigger pip of reaction induced potential signal degrade condition; First logic control circuit receives trigger pip; Accomplish the main and auxiliary switching that the frequency measurement with constant-precision circuit such as helps, promptly start frequency measurement with constant-precision circuit such as auxiliary, switch the main and auxiliary effect that the frequency measurement with constant-precision circuit such as helps so first logic control circuit has played; In other words conj.or perhaps under the constant situation of canonical reference pulsed frequency rolling counters forward (because primary standard reference pulse sample number is identical with auxiliary criteria reference pulse sample number; So primary standard reference pulse frequency counter is identical with the counting of auxiliary criteria reference pulse frequency counter) regulated the function of canonical reference pulsed frequency, convert it into F0 ' by F0, the time of minimizing frequency measurement process.Each frequency counter reads in MCU with count value separately through second logic control circuit; MCU calculates and treats measured frequency Fx; Realize unicoil type vibration wire instrument etc. frequency measurement with constant-precision; So second logic control circuit plays the generation interrelated logic, read in MCU to the corresponding counts value, and before measuring with the effect of each counter initialization zero clearing.
In preferred embodiment shown in Figure 2; The unique texture of frequency measurement with constant-precision circuit such as be provided with; Comprise two cover circuit: frequency measurement with constant-precision circuit such as main and frequency measurement with constant-precision circuit such as auxiliary; To different situations, start corresponding circuit, carry out computing according to each count value of frequency measurement with constant-precision circuit such as master when conventional and finally obtain treating measured frequency; When unusual, start frequency measurement with constant-precision circuit such as auxiliary; And finally each count value of frequency measurement with constant-precision circuit such as auxiliary is carried out computing and finally obtains treating measured frequency, should give up resulting each count values of frequency measurement with constant-precision circuit such as main this moment, perhaps with its read in MCU as just etc. the reference data of frequency measurement with constant-precision.Certainly; As frequency measurement with constant-precision devices such as a kind of unicoil type vibration wire instruments, its etc. the frequency measurement with constant-precision circuit can adopt other structures, as only accomplishing through circuit kit; Amplitude attenuation situation according to the induced potential signal that produces behind the type vibration wire instrument exciting; Adaptively modifying frequency measurement strategy the self-adaptation adjustment of the canonical reference pulsed frequency in the frequency measurement with constant-precision circuit such as carries out through logic control circuit, through changing the mode of canonical reference pulsed frequency; In the Measuring Time of frequency measurement with constant-precision circuit such as minimizing; From the induced potential signal, obtain enough induced potential impulse smaple numbers, precision such as guaranteed, improved the reliability of frequency measurement with constant-precision such as unicoil type vibration wire instrument.
The perfect measurement process of this frequency measuring equipment is following: be connected to the output terminal of signal generator to the frequency measurement coil through on-off circuit, promptly be communicated with exciting device and prepare exciting, accumulation signal affacts on the frequency measurement coil; The frequency measurement coil under the effect of permanent magnet, produces the electromagnetic force of alternation owing to applied alternation frequency sweep accumulation signal thereby had exchange current to flow through, and drives string wire generation mechanical vibration.After string wire produces mechanical vibration; By getting in touch between on-off circuit shutoff signal generator and the frequency measurement coil; Simultaneously be connected to the frequency measurement coil input end of amplifying circuit, promptly be communicated with the pick-up device (the pick-up device can be regarded as comprise amplifying circuit, shaping circuit, etc. frequency measurement with constant-precision circuit and induced potential decay observation circuit) prepare pick-up.Suitably wait for a period of time; Let the mechanical vibration of string wire form the standing wave of single-frequency; Because string wire vibration, alternation cutting magnetic line form the induced potential signal (induced potential signal waveform such as Fig. 3, shown in Figure 4) consistent with string wire mechanical vibration frequency at frequency measurement coil two ends.This induced potential telecommunications is amplified through the amplifying circuit inlet signal; As this induced potential signal is amplified to 2～3V from 5mV; This induced potential signal is after amplifying; One the tunnel gets into induced potential decay observation circuit, produces the trigger pip of reflection induced potential signal degrade condition, starts frequency measurement with constant-precision circuit such as auxiliary; The square wave of same frequency is carried out generating behind the shaping circuit in another road, gets into frequency measurement with constant-precision circuit such as main.FPGA/CPLD is according to preset steering logic; If the induced potential signal waveform attenuation ratio of amplifying is slower; As shown in Figure 3, induced potential decay observation circuit does not send trigger pip, and is auxiliary etc., and the frequency measurement with constant-precision circuit does not start; The induced potential impulse smaple number that this moment, MCU obtained according to frequency measurement with constant-precision circuit count such as main and the count value of primary standard reference pulse frequency counter calculate the frequency Fx of string wire; If induced potential signal waveform attenuation ratio is rapider, and is as shown in Figure 4, induced potential decay observation circuit sends trigger pip, triggers frequency measurement with constant-precision circuit such as auxiliary; Logic control circuit carries out by the switching of frequency measurement with constant-precision circuit such as master to frequency measurement with constant-precision circuit such as assisting; And according to the main and auxiliary startup situation that helps frequency measurement circuit; Produce interrelated logic; Read in MCU to corresponding count value, MCU treats measured frequency through calculating, and realizes the measurement of unicoil type vibration wire instrument frequency.
Fig. 7 is the preferred flow charts of the frequency measurement method of unicoil type vibration wire instrument of the present invention.This method comprises the steps:
A, frequency measurement coil 2 two ends in unicoil type vibration wire instrument shown in Figure 1 apply the frequency sweep accumulation signal of alternation; The practical implementation step can be with the A of frequency measurement coil 2, the output terminal that the B two ends are connected to signal generator; The frequency sweep accumulation signal that signal generator produces alternation is applied to frequency measurement coil 2 two ends; Frequency measurement coil 2 is owing to applied the frequency sweep accumulation signal of alternation thereby had exchange current to flow through; Under the effect of permanent magnet 3, form alternating electromagnetic force, drive string wire 1 mechanical vibration take place;
B, cancel the frequency sweep accumulation signal, i.e. annexation between cut-off signal generator and the frequency measurement coil 2; Suitable time-delay; Let the mechanical vibration of string wire 1 form the standing wave of single-frequency, because string wire 1 mechanical vibration, alternation cutting magnetic line form the induced potential signal consistent with string wire mechanical vibration frequency at frequency measurement coil 2 two ends; Its waveform is the damped oscillation waveform; In the different operation phase, the induced potential signal degrade condition is different to unicoil type vibration wire instrument, and Fig. 3 is the slow induced potential signal waveforms of amplitude fading; Fig. 4 is the fast induced potential signal waveforms of amplitude fading;
C, the induced potential signal is amplified, can pass through amplifying circuit work, amplifying circuit is amplified to 2～3V with this induced potential signal from 5mV, and the induced potential signal frequency is for treating measured frequency Fx;
D, the induced potential signal after will amplifying are divided into two-way: the one tunnel will be through the amplitude attenuation situation of induced potential decay monitoring circuit monitors induced potential signal; The structure of induced potential decay observation circuit can adopt block diagram shown in Figure 5; And when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value, to etc. the frequency measurement with constant-precision circuit trigger pip is provided; Another road becomes the same frequency square wave with induced potential signal shaping, frequency measurement with constant-precision circuit such as entering; Frequency measurement with constant-precision circuit such as main and frequency measurement with constant-precision such as frequency measurement with constant-precision circuit such as auxiliary carries out are set in its medium frequency measurement with constant-precision circuit; Primary standard reference pulse frequency F0 in the frequency measurement with constant-precision circuit 5 such as the composition etc. the frequency measurement with constant-precision circuit can adopt block diagram shown in Figure 6, and is main is less than the auxiliary criteria reference pulse frequency F0 ' in the frequency measurement with constant-precision circuit 6 such as auxiliary; The trigger pip of the amplitude attenuation situation of above-mentioned one tunnel reflection induced potential signal that produces starts frequency measurement with constant-precision circuit such as auxiliary, and the same frequency square wave that another road produces gets into main and auxiliary frequency measurement with constant-precision circuit such as help simultaneously;
E, etc. control logic circuit is set in the frequency measurement with constant-precision circuit; If induced potential signal waveform attenuation ratio is slower; As shown in Figure 3; Frequency measurement with constant-precision circuit such as induced potential decay observation circuit does not send trigger pip, and is auxiliary do not start, and this moment is by frequency measurement with constant-precision such as frequency measurement with constant-precision circuit completion such as masters; If induced potential signal waveform attenuation ratio is rapider; As shown in Figure 4; Induced potential decay observation circuit sends trigger pip; Trigger frequency measurement with constant-precision circuit such as auxiliary, control logic circuit such as leads at the switching of frequency measurement with constant-precision circuit to frequency measurement with constant-precision circuit such as auxiliary, because induced potential signal attenuation shown in Figure 4 is rapider; So after switching to frequency measurement with constant-precision circuit such as auxiliary; Can be under the constant situation of canonical reference pulsed frequency rolling counters forward (being that primary standard reference pulse frequency counter is identical with the counting of auxiliary criteria reference pulse frequency counter), increased canonical reference pulsed frequency (F0＜F0 '), reduce the time of frequency measurement process;
F, logic control circuit judge the process of measuring according to the main and auxiliary startup situation that the frequency measurement with constant-precision circuit such as helps, and produce interrelated logic, read in MCU to the count value of appropriate counter, and MCU calculates and treats measured frequency Fx.
Frequency measurement with constant-precision methods such as the unicoil type vibration wire instrument that the present invention relates to; Measure based on count frequency; Can be according to the waveform attenuating situation of the induced potential signal that produces behind the unicoil type vibration wire instrument exciting, adaptively modifying frequency measurement strategy is introduced main and auxiliary frequency measurement with constant-precision circuit such as help; To different situations, self-adapting start is main and auxiliary the frequency measurement with constant-precision circuit such as to help; Through changing the mode of standard reference frequency; In the Measuring Time of frequency measurement with constant-precision such as minimizing; From the induced potential signal, obtained enough induced potential impulse smaple numbers, guaranteed equal precision measurement, to the duty of different operation phase of unicoil type vibration wire instrument; Have good adaptive faculty, the safety monitoring that can satisfy Geotechnical Engineering is to the reliability of safety monitoring instrument and the requirement that guarantees measuring accuracy.
Should be pointed out that the above embodiment can make those skilled in the art more fully understand the invention, but do not limit the present invention in any way creation.Therefore; Although this instructions has carried out detailed explanation with reference to accompanying drawing and embodiment to the invention,, those skilled in the art are to be understood that; Still can make amendment or be equal to replacement the invention; In a word, all do not break away from the technical scheme and the improvement thereof of the spirit and the scope of the invention, and it all should be encompassed in the middle of the protection domain of the invention patent.
Claims (10)
- A unicoil type vibration wire instrument etc. the frequency measurement with constant-precision method; At first make frequency measurement coil two ends generate and string wire natural frequency induced potential signal consistent, amplitude attenuation through the string wire exciting; The count value of frequency measurement with constant-precision circuit according to the canonical reference pulsed frequency counting device of induced potential impulse smaple number that counts to get and setting such as pass through then; Calculate the frequency of string wire; It is characterized in that, after frequency measurement coil two ends generate said induced potential signal, also pass through the amplitude attenuation situation of induced potential decay monitoring circuit monitors induced potential signal; And in the amplitude attenuation speed that monitors the induced potential signal during to predetermined value; To etc. the frequency measurement with constant-precision circuit trigger pip is provided, the trigger pip that frequency measurement with constant-precision circuit such as said provides according to induced potential decay observation circuit, the canonical reference pulsed frequency in the frequency measurement with constant-precision circuit such as adjustment such as adjust at the Measuring Time of frequency measurement with constant-precision circuit.
- 2. unicoil type vibration wire instrument according to claim 1 etc. the frequency measurement with constant-precision method; It is characterized in that; Frequency measurement with constant-precision circuit such as main and frequency measurement with constant-precision such as frequency measurement with constant-precision circuit such as auxiliary carries out are set in waiting frequency measurement with constant-precision circuit; Primary standard reference pulse frequency in the frequency measurement with constant-precision circuit such as said master is less than the auxiliary criteria reference pulse frequency in the frequency measurement with constant-precision circuit such as auxiliary; When induced potential is decayed observation circuit when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value, through of the adjustment of frequency measurement with constant-precision circuit such as master to the Measuring Time of the frequency measurement with constant-precision circuit such as switching realization of frequency measurement with constant-precision circuit such as assisting.
- 3. unicoil type vibration wire instrument according to claim 2 etc. the frequency measurement with constant-precision method; It is characterized in that; Said induced potential decay monitoring circuit monitors to the induced potential decay just often; The count value of the primary standard reference pulse frequency counter that obtains through frequency measurement with constant-precision circuit count such as main being provided with in impulse smaple number and the frequency measurement with constant-precision circuit such as main of induced potential calculates the frequency of string wire; Said induced potential decay observation circuit is when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value; To frequency measurement with constant-precision circuit such as auxiliary trigger pip is provided; After receiving trigger pip, frequency measurement with constant-precision circuit such as auxiliary starts; And, calculate the frequency of string wire according to the count value of the auxiliary criteria reference pulse frequency counter that is provided with in the impulse smaple number of the induced potential that counts to get and the frequency measurement with constant-precision circuit such as auxiliary.
- According to claim 1 or 2 or 3 described unicoil type vibration wire instruments etc. the frequency measurement with constant-precision method; It is characterized in that; After frequency measurement coil two ends generate said induced potential; Earlier the induced potential signal is amplified, the attenuation of the induced potential after amplifying through induced potential decay monitoring circuit monitors is again carried out the induced potential signal that amplifies after the shaping frequency measurement with constant-precision circuit such as input more simultaneously.
- According to claim 2 or 3 described unicoil type vibration wire instruments etc. the frequency measurement with constant-precision method; It is characterized in that; Realize by of the switching of frequency measurement with constant-precision circuit such as master through logic control circuit to frequency measurement with constant-precision circuit such as assisting; And induced potential impulse smaple number that frequency measurement with constant-precision circuit and frequency measurement with constant-precision circuit count such as auxiliary obtain such as will lead and the count value of each frequency counter is read in microcontroller, calculate the frequency of string wire by microcontroller.
- A unicoil type vibration wire instrument etc. the frequency measurement with constant-precision device; Comprise exciting device, on-off circuit and etc. the frequency measurement with constant-precision circuit, said on-off circuit at times with exciting device with etc. the frequency measurement with constant-precision circuit respectively with unicoil type vibration wire instrument in the frequency measurement coil link to each other; Saidly be meant at times: on-off circuit is communicated with exciting device and frequency measurement coil earlier, and exciting device applies the frequency sweep accumulation signal of alternation at frequency measurement coil two ends, formation alternating electromagnetic force under the effect of permanent magnet, driving string wire generation mechanical vibration; On-off circuit cuts off being connected between exciting device and the frequency measurement coil again, and the mechanical vibration of string wire form the standing wave of single-frequency, and frequency measurement coil two ends form and string wire mechanical vibration frequency induced potential signal consistent, amplitude attenuation; On-off circuit be communicated with again the frequency measurement coil with etc. the frequency measurement with constant-precision circuit; Frequency measurement with constant-precision circuit such as said is according to the count value of the canonical reference pulsed frequency counting device of induced potential impulse smaple number that counts to get and setting; Calculate the frequency of string wire; It is characterized in that; Also comprise induced potential decay observation circuit, said induced potential decay observation circuit with etc. the frequency measurement with constant-precision circuit link to each other the amplitude attenuation situation of the induced potential signal of induced potential decay monitoring circuit monitors frequency measurement coil two ends generation; And when the amplitude attenuation speed that monitors the induced potential signal reaches predetermined value; To etc. the frequency measurement with constant-precision circuit trigger pip is provided, the trigger pip that frequency measurement with constant-precision circuit such as said also provides according to induced potential decay observation circuit, the canonical reference pulsed frequency in the frequency measurement with constant-precision circuit such as adjustment such as adjust at the Measuring Time of frequency measurement with constant-precision circuit.
- 7. unicoil type vibration wire instrument according to claim 6 etc. the frequency measurement with constant-precision device; It is characterized in that; Frequency measurement with constant-precision circuit such as said comprises frequency measurement with constant-precision circuit such as main, frequency measurement with constant-precision circuit, logic control circuit and microcontroller such as auxiliary; Said logic control circuit links to each other with microcontroller with induced potential decay observation circuit respectively; Frequency measurement with constant-precision circuit such as said master comprise main frequency counter to be measured and primary standard reference pulse frequency counter; Said frequency measurement with constant-precision circuit such as auxiliary comprises auxiliary frequency counter to be measured and auxiliary criteria reference pulse frequency counter; Said primary standard reference pulse frequency is less than auxiliary criteria reference pulse frequency, after said logic control circuit receives the trigger pip of induced potential decay observation circuit, through controlling the adjustment of frequency measurement with constant-precision circuit such as main to the Measuring Time of the frequency measurement with constant-precision circuit such as switching realization of frequency measurement with constant-precision circuit such as auxiliary.
- 8. unicoil type vibration wire instrument according to claim 7 etc. the frequency measurement with constant-precision device; It is characterized in that; Also comprise amplifying circuit and shaping circuit; Said on-off circuit links to each other with induced potential decay observation circuit through amplifying circuit; Said on-off circuit successively through amplifying circuit and shaping circuit with etc. the frequency measurement with constant-precision circuit link to each other, input to the induced potential observation circuit of decaying after the induced potential that said amplifying circuit generates frequency measurement coil two ends amplifies again to monitor, said shaping circuit carries out the induced potential signal of amplification after the shaping frequency measurement with constant-precision circuit such as input again.
- 9. unicoil type vibration wire instrument according to claim 7 etc. the frequency measurement with constant-precision device, it is characterized in that said logic control circuit is FPGA or CPLD.
- 10. unicoil type vibration wire instrument according to claim 8 etc. the frequency measurement with constant-precision device; It is characterized in that; Said induced potential decay observation circuit comprises precise rectification circuit, filtering circuit and the voltage comparator circuit that connects successively; Said precise rectification circuit links to each other with amplifying circuit, and voltage comparator circuit links to each other with logic control circuit.
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| CN104180839A (en) * | 2014-07-15 | 2014-12-03 | 常州大学 | Rapid measurement method for vibrating-wire sensor and detection circuit |
| CN104567975A (en) * | 2015-01-13 | 2015-04-29 | 基康仪器股份有限公司 | Inspection and calibration device and method for monocoil vibrating wire instrument |
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| CN106840367A (en) * | 2017-03-23 | 2017-06-13 | 北京航空航天大学 | A kind of floated low-frequency shock transducer of multiaxis |
| CN108375413A (en) * | 2017-01-31 | 2018-08-07 | 计算系统有限公司 | Detect the fault collection of vibration data |
| CN108776251A (en) * | 2018-03-30 | 2018-11-09 | 清华大学 | Induced potential measurement method and system |
| CN109506716A (en) * | 2018-12-25 | 2019-03-22 | 岩联(武汉)科技有限公司 | A kind of type vibration wire acquisition terminal and its excitation frequency range acquisition method |
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| CN110426003A (en) * | 2019-08-02 | 2019-11-08 | 上海西派埃自动化仪表工程有限责任公司 | Frequency measuring method, device, equipment and storage medium based on vibrating string extensometer |
| CN110702150A (en) * | 2019-10-11 | 2020-01-17 | 贵州省质安交通工程监控检测中心有限责任公司 | Optimized sweep frequency excitation method for vibrating wire collector |
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