CN201429461Y - Vibration signal acquisition unit - Google Patents

Abstract

The utility model relates to a vibration signal acquisition unit. The vibration signal acquisition unit comprises an acceleration sensor, an A/D conversion module, a resonance circuit, a demodulationcircuit, and an anti-aliasing filtering circuit, wherein, the resonance circuit is used for processing signals output by the acceleration sensor and outputting the result; the demodulation circuit isused for controlling the cut-off frequency and the gain of signals output by the resonance circuit and outputting the result; the anti-aliasing filtering circuit is used for processing signals outputby the demodulation circuit and outputting the result; and signals output by the anti-aliasing filtering circuit are output through the A/D conversion module. As the resonance demodulation technologyis adopted, and a resonator is arranged between the acceleration sensor and the A/D conversion module, the utility model can separate (high-frequency) breakdown signals, and isolates noise signals effectively, thereby improving the performance of a data acquisition system to a great extent.

Description

A kind of vibration signal collector

Technical field

The utility model relates to signal picker, particularly vibration signal collector.

Background technology

At present, vibration signal collector generally comprises acceleration transducer and A/D modular converter, and the detected vibration signal of acceleration transducer directly is defeated by computing machine by the A/D modular converter.

In industry spot, because some equipment (as the bearing of low-speed heave-load device etc.) gyro frequency very low (about 0.1Hz), frequency domain is but very wide, also mixed a lot of noise signals in the vibration signal, and existing acceleration transducer can not separate these noise signals effectively, therefore, in industry spot, be a difficult problem for the vibration signals of low-speed heave-load device always.

Summary of the invention

Technical problem to be solved in the utility model is: a kind of effectively vibration signal collector of burbling noise signal is provided.

The utility model solves the problems of the technologies described above the technical scheme that is adopted:

A kind of vibration signal collector, it comprises:

Acceleration transducer,

The A/D modular converter,

The resonant circuit that is used for the signal of acceleration transducer output is handled and exported,

Be used for to the signal of resonant circuit output carry out cutoff frequency and gain control and output demodulator circuit,

Be used for anti-aliasing filter circuit that the signal of demodulator circuit output is handled and exported;

The signal of anti-aliasing filter circuit output is by the output of A/D modular converter.

In the such scheme, demodulator circuit comprises:

The high-pass filtering circuit that is used for the signal of resonant circuit output is handled and exported,

Be used for unipolarity circuit that the signal of high-pass filtering circuit output is handled and exported.

In the such scheme, vibration signal collector also comprises control module; Control module comprises:

Microprocessor,

The communication module that is used for microprocessor and external unit communication;

The signal of anti-aliasing filter circuit output is by A/D modular converter input microprocessor.

In the such scheme, control module also comprises control and display part, and control is connected with the microprocessor communication with the display part.

In the such scheme, be provided with the photoelectricity coupled circuit between acceleration transducer and the resonant circuit.

In the such scheme, be provided with differential amplifier circuit between photoelectricity coupled circuit and the resonant circuit.

Advantage of the present utility model is:

1, the utility model adopts resonance demodulation technique, between acceleration transducer and A/D modular converter, be provided with by one " resonator ", fault-signal (high frequency) is separated,, can be promoted the performance of data acquisition system (DAS) to a great extent the noise signal effective isolation.

The utility model principle of work is:

Resonant circuit can be rejected the low-frequency spectra composition of the vibration and the impact of nearly all low frequency, keeps the radio-frequency component that impacts; Use its resonance-characteristic, impact is carried out resonance response, realizes the spatial transform of waveform, can realize that the paired pulses impact is amplified, the resonance conversion of broadening.

Demodulator circuit is used to realize cutoff frequency and gain control.

The anti-aliasing filter circuit is used to prevent the appearance of signal aliasing phenomenon.

2, demodulator circuit adopts hardware to realize the demodulation of high pass absolute value, is made of Hi-pass filter and unipolarity circuit (absolute value circuit, i.e. all-wave precise rectification circuit), and it is simple in structure, and control is convenient.

3, vibration signal collector also comprises control module, and control module can be vibration signal collector and realizes man-machine interaction, carries out communication easily etc. with the outside and create conditions.

4, be provided with the photoelectricity coupled circuit between acceleration transducer and the resonant circuit, carry out photoelectricity and isolate, with the strong and weak electricity of system separately, the interference free performance of enhanced system and safety coefficient.

Though 5,, in transmission course, have decay because the impact signal of acceleration transducer output amplifies through incorporated amplifier, and its amplitude is still very little, directly it is not handled if do not amplify, then distorted signals is quite serious.Therefore, be provided with differential amplifier circuit between photoelectricity coupled circuit of the present utility model and the resonant circuit.

Description of drawings

Fig. 1 is the structured flowchart of the utility model vibration signal collector embodiment

Fig. 2 is the circuit theory diagrams of photoelectricity coupled circuit

Fig. 3 is the circuit theory diagrams of differential amplifier circuit

Fig. 4 is the circuit theory diagrams of resonant circuit

Fig. 5 is the circuit theory diagrams of high-pass filtering circuit

Fig. 6 is the circuit theory diagrams of unipolarity circuit

Fig. 7 is the circuit theory diagrams of anti-aliasing filter circuit

Fig. 8 is the circuit theory diagrams of A/D modular converter

Fig. 9 is the time domain waveform through the vibration signal behind the resonance and demodulation

Figure 10 is the amplitude spectrum through the vibration signal behind the resonance and demodulation

Figure 11 is undressed original signal

Embodiment

As shown in Figure 1, the utility model vibration signal collector embodiment comprises: acceleration transducer, A/D modular converter, the resonant circuit that is used for the signal of acceleration transducer output is handled and exported, be used for to the signal of resonant circuit output carry out cutoff frequency and gain control and output demodulator circuit, be used for anti-aliasing filter circuit, control module that the signal of demodulator circuit output is handled and exported.

Demodulator circuit comprises: the high-pass filtering circuit that is used for the signal of resonant circuit output is handled and exported, be used for unipolarity circuit that the signal of high-pass filtering circuit output is handled and exported.

Control module comprises: microprocessor, be used for communication module, control and the display part of microprocessor and external unit communication.Control is connected with the microprocessor communication with the display part.Control and display part are touch-screen.

The signal of anti-aliasing filter circuit output is by A/D modular converter input microprocessor.

Be provided with the photoelectricity coupled circuit between acceleration transducer and the resonant circuit, be provided with differential amplifier circuit between photoelectricity coupled circuit and the resonant circuit.

The acceleration transducer of present embodiment is used for gathering the acceleration signal of target device vibration, and exports with the form of voltage; Acceleration transducer is provided the voltage and the constant current source of excitation by sensor interface.Acceleration transducer collects the signal condition that at first carries out a front end behind the vibration signal, and signal condition is realized by hardware circuit in the utility model.

Acceleration transducer is adopted into simulating signal, at first carries out the photoelectricity isolation and separates the interference free performance of enhanced system and safety coefficient with the strong and weak electricity with system.The photoelectricity coupled circuit of present embodiment is a linear optical coupling, adopts the separation principle and the common optocoupler of linear optical coupling not to have difference, just the single-shot list of common optocoupler is received pattern and changes a little, increases an optical receiving circuit that is used to feed back and is used for feedback.Though two optical receiving circuits all are non-linear, the nonlinear characteristic of two optical receiving circuits all is the same, like this, just can offset the non-linear of through path by the non-linear of feedback network, realizes linear purpose of isolating thereby reach.

As shown in Figure 2, present embodiment has selected for use the high-accuracy linear optical coupling of HCNR200 type of Agilent company to build the photoelectricity coupled circuit, has adopted the high-accuracy amplifier of LMV321 of TI company to assist the realization voltage of signals to isolate again.The output signal of acceleration transducer is imported from Vin, and photoelectricity coupled circuit output signal is exported from Vout.

As shown in Figure 3, present embodiment has selected for use the PGA205 of U.S. Burr-Brown company to build differential amplifier circuit.The maximum characteristics of this chip are for can realize 1,2,4,8 times gain control by online programming.Photoelectricity coupled circuit output signal is imported from Ains, and the signal after the amplification is from Aout or AoutG output.

The output of amplifier is meant with respect to reference edge, usually with reference edge ground connection.For making device reach the highest precision, the output terminal of amplifier must be connected to feedback end.Higher or when noise is arranged when source impedance, should respectively add the decoupling capacitor of 1 μ F in positive and negative power pins.Amplifier Gain is by the logic level decision of 15,16 pins.Wherein logical one is defined as greater than 2V digitally, digitally can be connected on V-or the power supply than the low 4V of V+.Numeral incoming level TTL and COMS compatibility.When using logical zero, the electric current of nearly 1 μ A flows out from digital input pin, and electric current is 0 when using logic level " 1 ".

PGA205 does not have latch function to digital input logic signal (A0, A1), and the conversion of logic input signal will cause new gain selection immediately, be approximately 1 μ s switching time.The pass of input logic A1, A0 and gain is: (0,0) amplifies 1 times, and (0,1) amplifies 2 times, and (1,0) amplifies 4 times, and (1,1) amplifies 8 times.

PGA205 can also slacken the interference on the sensor electrical cable in addition.The sensor cable skin is a screen layer, is proved by anti-interference theory and practice, when the screen layer of the cable of transmission weak signal adds certain potentials, with the interference that reduces greatly to be introduced by distributed capacitance coupling between screen layer and the heart yearn.

As shown in Figure 4, the resonant circuit of present embodiment selects for use the high-accuracy bandpass filter of MAX268 of MAXIM company to realize circuit.MAX268 inside comprises an amplifier and two second-order filter parts, can realize that precision very high bandpass filtering centre frequency, quality factor and operator scheme can set by pin input.

In the bandpass filter that adopts the MAX268 design, need to determine centre frequency f0 and passband width.Choosing of f0 will be determined according to the rotating speed of concrete plant equipment, because of the mechanical fault signal all comprises the characteristic frequency that is directly proportional with rotating speed, therefore determines f0 according to characteristic frequency, and then selects passband width BW, passes through formula

Q＝f ₀/BW

Obtain quality factor.In selected bandwidth range, the failure impact signal that only allows to contain radio-frequency component passes through, and filtering low-frequency noise and undesired signal, thereby realize the effect that fault is impacted does not just have demodulation waveforms output.

By the level syntagmatic of internal clocking fclk and five programmable input pin F4～F0, the ratio of control clock frequency fclk and bandpass filtering centre frequency f0, centre frequency that can this accommodation zone bandpass filter.Five pins of F0～F4 are capable of being combined to go out 32 kinds of states, and the decimal integer size that this five bit of F4～F0 is represented represents that with alphabetical N its value scope is 0～31.Computing formula is as follows:

N＝(f _clk/πf ₀)-13

Suppose that if centre frequency f0 is set be 30KHz, crystal oscillator frequency is selected 1.8432MHz, then N=(fclk/ π f0)-13=6.557 is arranged according to following formula, therefore N gets 6, can determine that by N everybody value of F4～F0 is followed successively by 00110, be F4, F3, F0 connect power-(5V), F2, F1 connect power supply just (+5V).

The passband width that bandpass filter is set is 6KHz, then quality factor

Q＝f ⁰/BW＝30/6＝5。

The selection of Q can realize by the level syntagmatic of these seven input pins able to programme of control Q6～Q0.Seven pins are capable of being combined to go out 128 kinds of states, and the decimal integer size that this seven bit of Q6～Q0 is represented represents that with alphabetical N its value scope is 0～127.Computing formula is as follows:

N＝128-(64/Q)

Q=5 substitution formula is got, N=128-(64/5)=115.2, so N gets 115, then Q6～Q0 is respectively 1110011, promptly Q6, Q5, Q4, Q1, Q0 connect power supply just (+5V), Q3, Q2 connect power-(5V).

After having determined centre frequency f0, bandwidth BW and the quality factor q of wave filter, can draw the numerical value of resistance in the peripheral circuit according to the computing formula in the MAX268 databook.

After signal has passed through one-level, secondary resonator, be actually and passed through a two-layer bandpass filtering link, just the signal of low frequency has been carried out high frequency modulated, this modulated process can effectively be preserved the fault-signal link, and after the modulation link, to carry out demodulation accordingly, just the relevant composition of carrier wave is removed, restored the signal that we want, through the operation of this modulation-demodulation, can in complete preservation fault-signal, effectively reject various interference components.

The demodulator circuit that present embodiment adopted is by being used for the high-pass filtering circuit that the signal of resonant circuit output is handled and exported and being used for the unipolarity circuit (being the all-wave precise rectification circuit) that the signal of high-pass filtering circuit output is handled and exported is constituted.The high-pass filtering circuit circuit as shown in Figure 5, the output signal of resonant circuit is imported from Vin, the high-pass filtering circuit output signal is exported from Vout.

The voltage controlled voltage source form is adopted in the design of Hi-pass filter, and it only needs an operational amplifier just can make up circuit very easily.Both introduce negative feedback in the circuit, introduced positive feedback again.When signal frequency went to zero, it is infinitely great that the reactance of C1 is tending towards, thereby positive feedback is very weak; When signal frequency was tending towards infinity, the reactance of C2 went to zero, thereby arithmetical unit in-phase input end voltage is tending towards input voltage vin.Can imagine, proper as long as positive feedback is introduced, voltage amplification factor numerical value is increased, can not cross again and produce self-sustained oscillation by force because of positive feedback.

In Fig. 5, the closed loop gain of in-phase input end is

$G=1+\frac{R_4}{{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="Y2009200869150010H3.png,Y2009200869150011H1.png"\; state="\{\{state\}\}">R</figure-callout>}}_3},$

Establishing gain herein is 2, then

R ₄＝R ₃，

Choosing resistance value is 13K.The centre frequency of Hi-pass filter can be by formula

${\mathrm{<figure-callout\; id="0"\; label="f"\; filenames="Y2009200869150009H2.png,Y2009200869150012H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_0=\frac{1}{2\mathrm{\&pi;}\sqrt{R_1{R}_2{C}_1{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y2009200869150009H2.png,Y2009200869150010H1.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}}$

Try to achieve.

The unipolarity circuit also is absolute value circuit, control system gain when realizing demodulation, its circuit as shown in Figure 6, the output signal of high-pass filtering circuit is imported from Vin, the unipolarity circuit output signal is exported from Vout.

With the shared detection demodulation function that can realize signal of Hi-pass filter.Adopt programmable-gain from cushioning absolute value circuit.This circuit can provide very high input impedance to signal source, so can be called from buffer circuit, from the connection of circuit also as can be seen, not only input end cushions, and output terminal is also cushioned by amplifier B.This circuit has by Graham and proposes.Circuit only needs three precision resistances, and the characteristics of circuit are that resistance is suitably selected, and can carry out gain programming at an easy rate.In the circuit, A finishes the input buffering function, and A, D1 and D2 carry out gain control.During the positive signal input, D1 connects, and the follower increasing benefit loop, addedlink loop, gaining loop comprises A and B.During the negative signal input, D2 connects, and A drives the B of anti-phase configuration work.Gain n can be the different value greater than 1, and degree of freedom is bigger relatively.In the design, the n value is 2, and resistance value is very convenient, and can realize with single electric resistance array.During positive input, A and B are with series system work, so control spurious oscillation with electric capacity C0.Gain according to the rules and used amplifier type, electric capacity is answered optimal selection.Each parameter has following relation in the circuit:

$n=\frac{R_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y2009200869150009H2.png,Y2009200869150010H1.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

${\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="Y2009200869150010H3.png,Y2009200869150011H1.png"\; state="\{\{state\}\}">R</figure-callout>}}_3={\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y2009200869150009H2.png,Y2009200869150010H1.png"\; state="\{\{state\}\}">R</figure-callout>}}_2*\frac{n+1}{n-1}.$

Add the appearance that an anti-aliasing filter circuit prevents the signal aliasing phenomenon behind the unipolarity circuit.Present embodiment adopts 4 rank chebyshev low-pass filters to realize anti-aliasing operation, its application circuit as shown in Figure 7, the output signal of unipolarity circuit is imported from Vin, the anti-aliasing filter circuit output signal is exported from Vout.

As shown in Figure 8, the A/D modular converter adopts ADS7805 to realize that the A/D of signal changes, and is connected with the microprocessor master chip S3C2410 of control module, and promptly the MD0---MD15 pin links to each other with the DATA0---DATA15 pin of S3C2410.

Control module has adopted touch screen technology for realizing man-machine interaction, and the touch-screen controlling resource on the S3C2410 sheet is directly drawn, and realizes the control of user of service to instrument; For realizing the communication of data collector and host computer, draw the serial ports and the USB mouth resource of master chip, give host computer with interim data upload of preserving on the acquisition instrument, conveniently on host computer, data analysis is reached a conclusion.

With S3C2410 is the system control module of master chip, is responsible for whole acquisition system is carried out scheduling of resource and distribution, realizes the interface that slave computer and host computer carry out communication.

The time domain waveform that the utility model vibration signal collector embodiment exports vibration signal as shown in Figure 9, the vibration signal amplitude spectrum of output as shown in figure 10, original signal is as shown in figure 11.As can be seen, present embodiment is separated fault-signal (high frequency), and noise signal has been carried out effective isolation among Fig. 9-11.Can see significantly that through comparison present embodiment is reasonable for the extraction effect of low-speed heave-load device fault-signal, reach the state of imagination.

Claims (6)

1, a kind of vibration signal collector, it comprises acceleration transducer, A/D modular converter; It is characterized in that: it also comprises:

The resonant circuit that is used for the signal of acceleration transducer output is handled and exported,

Be used for to the signal of resonant circuit output carry out cutoff frequency and gain control and output demodulator circuit,

Be used for anti-aliasing filter circuit that the signal of demodulator circuit output is handled and exported;

The signal of anti-aliasing filter circuit output is by the output of A/D modular converter.

2, vibration signal collector as claimed in claim 1, it is characterized in that: demodulator circuit comprises:

The high-pass filtering circuit that is used for the signal of resonant circuit output is handled and exported,

Be used for unipolarity circuit that the signal of high-pass filtering circuit output is handled and exported.

3, vibration signal collector as claimed in claim 1 or 2 is characterized in that: it also comprises control module; Control module comprises:

Microprocessor,

The communication module that is used for microprocessor and external unit communication;

The signal of anti-aliasing filter circuit output is by A/D modular converter input microprocessor.

4, vibration signal collector as claimed in claim 3 is characterized in that: control module also comprises control and display part, and control is connected with the microprocessor communication with the display part.

5, vibration signal collector as claimed in claim 1 is characterized in that: be provided with the photoelectricity coupled circuit between acceleration transducer and the resonant circuit.

6, vibration signal collector as claimed in claim 5 is characterized in that: be provided with differential amplifier circuit between photoelectricity coupled circuit and the resonant circuit.

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