CN203838245U

CN203838245U - Device for measuring impedance angle of ultrasonic transducer by use of orthogonal correlation method

Info

Publication number: CN203838245U
Application number: CN201420235197.2U
Authority: CN
Inventors: 纪华伟; 李旭龙; 胡小平; 叶红仙; 赵志磊; 董昕頔
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2014-05-09
Filing date: 2014-05-09
Publication date: 2014-09-17
Anticipated expiration: 2024-05-09

Abstract

The utility model discloses a device for measuring the impedance angle of an ultrasonic transducer by use of an orthogonal correlation method. The device comprises a voltage sensor for measuring the voltage of a transducer, a current sensor for measuring the current of the transducer, a first conditioning circuit, a second conditioning circuit, an ARM Cortex-M3 microprocessor and a TFT-LCD display unit. The device is high in measuring precision, small in calculation quantity, applicable to non-synchronous sampling, and very suitable for high-frequency signal phase difference measuring. Voltage and current signal frequencies of the transducer in the working process can be acquired in real time, measurement error can be corrected according to the actual signal frequencies so as to obtain a high-accuracy transducer impedance angle, and the frequencies can provide a basis for an ultrasonic generator to realize frequency tracking.

Description

A kind of Orthogonal correlation method is measured the device of ultrasonic transducer angle of impedance

Technical field

The utility model belongs to electronic measuring technology field, is specifically related to measure for a kind of Orthogonal correlation method the device of ultrasonic transducer angle of impedance.

Background technology

In the ultrasonic cut process of cellular composite material, for tearing of overcoming in cutting process that cellular composite material occurs, press collapse, the problem such as burr and the distortion of core lattice, need to mate ultrasonic cut transducer used and ultrasonic generator, to obtain high transducer work efficiency and high crudy.But, in reality cutting, usually, due to the variation of the factors such as extraneous load, temperature, cause between generator and transducer not reaching good coupling, finally cause crudy and working (machining) efficiency extremely to reduce, damage sound vibrating system even when serious.Therefore, there is scholar to propose to adopt the mode of Dynamic Matching, make the dynamically variation of the resonance frequency of tracking sound vibrating system of generator output frequency, therefore need by the impedance of the online matching system that detects ultrasonic transducer and ultrasonic generator composition, and regulate accordingly the parameter of matching network, make sound vibrating system all the time in resonant condition, when not mating, the impedance of matching system is complex impedance, angle of impedance is non-vanishing, when resonance, angle of impedance is zero, therefore, be necessary the angle of impedance of the matching system forming by detection transducer and ultrasonic generator, judge that by the size of angle of impedance whether system is in resonant condition, and according to the parameter of the size adjustment matching network of angle of impedance, make sound vibrating system in resonant condition.

In engineering field, the measurement of angle of impedance adopts the phase differential between the voltage at transducer two ends and the electric current of the transducer of flowing through to detect more.Conventional method for measuring phase difference has zero passage method, Spectral Analysis Method and correlation method.Wherein, zero passage method is subject to extraneous factor impact, and sampling precision is not high.Frequency spectrum point-score is to utilize discrete Fourier transformation principle that time-domain signal is transformed to frequency domain, then determines the phase differential of two signals according to phase-frequency characteristic, but the method tends to produce spectrum leakage and fence effect.Correlation method is after two signals being made to related operation in time domain and then obtains phase differential.Relevant function method has good noise inhibiting ability, and fast response time can accurately measure phase differential, and real-time is stronger, but correlation method must be under synchronized sampling condition.But in actual measurement process, due to the impact of various factors, as undesirable in the performance of the slow fluctuation of measured signal frequency, hardware device etc., data system is difficult to accomplish strict synchronized sampling, and has circular error.In order to improve the accuracy of phase difference measurement, there is again multiple new method of measuring.As this spectrum estimation method of Bake, multiline interpolated DFT algorithm, windowed function method, asynchronous fft algorithm, neural network etc.

Summary of the invention

The utility model, for the deficiencies in the prior art, has proposed a kind of device of Orthogonal correlation method measurement ultrasonic transducer angle of impedance.

The technical solution that realizes the utility model object is:

Orthogonal correlation method is measured a device for ultrasonic transducer angle of impedance, and this device comprises the voltage sensor of measurement transducer voltage, current sensor, the first modulate circuit, the second modulate circuit, ARM Cortex-M3 microprocessor and the TFT-LCD display unit of measurement transducer electric current;

Voltage sensor is connected by Du Pont's line with the first modulate circuit signal input interface, and current sensor is connected by Du Pont's line with the second modulate circuit; The signal output interface of the first modulate circuit is connected with an analog to digital converter input port of ARMCortex-M3 microprocessor internal by Du Pont's line; The signal output interface of the second modulate circuit is connected with another analog to digital converter input port of ARM Cortex-M3 microprocessor internal by Du Pont's line; Connect ± 15V of voltage sensor power supply, connect+5V of current sensor power supply, connect+5V of the first modulate circuit power supply, connect+5V of the second modulate circuit power supply; Connect+5V of ARM Cortex-M3 microprocessor power supply, ARM Cortex-M3 microprocessor is connected by 8060 buses with TFT-LCD display screen;

The first described modulate circuit, comprise the first Hall voltage sensor U1, the first operational amplifier U2A, the second operational amplifier U2B, the 3rd operational amplifier U2C, four-operational amplifier U2D, the first resistance R 1, the second resistance R 2, the 3rd resistance R 3, the 4th resistance R 4, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7, the 8th resistance R 8, the 9th resistance R 9, the tenth resistance R 10, the 11 resistance R 11, the 12 resistance R 12, the 13 resistance R 13, the 14 resistance R 14, the 15 resistance R 15, the first capacitor C 1, the second capacitor C 2, the first diode D1 and the second diode D2, the model of the first Hall voltage sensor U1 is CHV-25P,

First resistance R 1 one end is connected with the input end In+ of voltage sensor, the other end is connected with 1 pin of Hall voltage sensor U1, the output terminal In-of voltage sensor is connected with 2 pin of Hall voltage sensor U1,3 pin of Hall voltage sensor U1 are connected with the negative pole of 15V power supply, 4 pin of Hall voltage sensor U1 are connected with the positive pole of 15V power supply, 5 pin of Hall voltage sensor U1 are connected with one end of the second resistance R 2, and the other end of the second resistance R 2 is connected to the ground, one end of the 3rd resistance R 3 is connected with 5 pin of Hall voltage sensor U1, the other end is connected with the positive input of the first operational amplifier U2A, the reverse input end of the first operational amplifier U2A is connected with output terminal, the positive power source terminal of the first operational amplifier U2A is connected with+15V power supply, the negative power end of the first operational amplifier U2A is connected with-15V power supply, the output terminal of the first operational amplifier U2A is connected with one end of the 4th resistance R 4, the other end of the 4th resistance R 4 is connected with one end of the 5th resistance R 5, the other end of the 5th resistance R 5 is connected with the positive input of the second operational amplifier U2B, one end of the first capacitor C 1 is connected with the other end of the 4th resistance R 4, the other end of the first capacitor C 1 is connected with the output terminal of the second operational amplifier U2B, one end of the second capacitor C 2 is connected with the positive input of the second operational amplifier U2B, the other end of the second capacitor C 2 is connected to the ground, one end of the reverse input end of the second operational amplifier U2B and the 6th resistance R 6, one end of the 7th resistance R 7 is connected, the other end of the 6th resistance R 6 is connected to the ground, the other end of the 7th resistance R 7 is connected with 7 ends of the second operational amplifier U2B, the positive power source terminal of the second operational amplifier U2B is connected with+15V power supply, the negative power end of the second operational amplifier U2B is connected with-15V power supply, one end of the 8th resistance R 8 is connected with the output terminal of the second operational amplifier U2B, the reverse input end of the other end of the 8th resistance R 8 and the 3rd operational amplifier U2C, one end of the 9th resistance R 9, one end of the 11 resistance R 11 is connected, the other end of the 9th resistance R 9 is connected with+5V power supply, the positive input of the 3rd operational amplifier U2C is connected with one end of the tenth resistance R 10, the other end of the tenth resistance R 10 is connected to the ground, the output terminal of the other end of the 11 resistance R 11 and the 3rd operational amplifier U2C, one end of the 12 resistance R 12 is connected, the positive power source terminal of the 3rd operational amplifier U2C is connected with+15V power supply, the 3rd operational amplifier U2C negative power end be connected with-15V power supply, the 12 other end of resistance R 12 and the reverse input end of four-operational amplifier U2D, one end of the 14 resistance R 14 is connected, the positive input of four-operational amplifier U2D is connected with one end of the 13 resistance R 13, the other end of the 13 resistance R 13 is connected to the ground, the 14 other end of resistance R 14 and 14 ends of four-operational amplifier U2D, one end of the 15 resistance R 15 is connected, the positive power source terminal of four-operational amplifier U2D is connected with+15V power supply, the negative power end of four-operational amplifier U2D is connected with-15V power supply, the anode of the other end of the 15 resistance R 15 and the first diode D1, the anodic bonding of the second diode D2 as output interface Out, connect+3.3V of the negative electrode of the first diode D1 power supply, the negative electrode of the second diode D2 is connected to the ground, transducer voltage output interface Out after modulate circuit 1 conditioning is connected with an input interface of microprocessor ARM Cortex-M3 internal mode number converter,

The second described modulate circuit 2, comprises the first Hall current sensor, and the first capacitor C 1, the first Hall current sensor model is ACS712-05B;

1 pin of the first Hall current sensor is connected and is connected with the signal input part of current sensor with 2 pin, 3 ends of the first Hall current sensor are connected and are connected with the signal output part of current sensor with 4 ends, 5 foots of the first Hall current sensor are connected with+5V power supply, 6 pin of the first Hall current sensor are connected with another input interface of microprocessor ARM Cortex-M3 internal mode number converter, 7 pin of the first Hall current sensor are connected with one end of the first capacitor C 1, the other end of the first capacitor C 1 is connected with 8 pin of the first Hall current sensor and ground connection.

Compared with prior art, its remarkable advantage is the utility model:

(1) a kind of improved Orthogonal correlation method is measured the device of ultrasonic transducer angle of impedance, high without complicated hardware circuit design, measuring accuracy, calculated amount is little, be applicable to non-synchronous sampling, meet signal real-time is required to higher occasion, and be applicable to very much the phase difference measurement of high-frequency signal.

(2) a kind of improved Orthogonal correlation method is measured the device of ultrasonic transducer angle of impedance, voltage, current signal frequency in can the Real-time Obtaining transducer course of work, according to actual signal frequency correction measuring error, obtain the transducer impedance angle of pin-point accuracy, and this frequency can also realize frequency-tracking for ultrasonic generator foundation is provided.

Brief description of the drawings

Fig. 1 is the device that a kind of improved Orthogonal correlation method of the present utility model is measured ultrasonic transducer angle of impedance.

Fig. 2 is the hardware circuit diagram that gathers ultrasonic transducer voltage signal modulate circuit 1 used.

Fig. 3 is the hardware circuit diagram that gathers ultrasonic transducer current signal modulate circuit 2 used.

Fig. 4 is that MATLAB is to the ultrasonic transducer angle of impedance measurement result comparison diagram before and after improving.

Embodiment

As shown in Figure 1, Figure 2, Figure 3 shows, Orthogonal correlation method is measured a device for ultrasonic transducer angle of impedance, and this device comprises the voltage sensor of measurement transducer voltage, current sensor, the first modulate circuit, the second modulate circuit, ARM Cortex-M3 microprocessor and the TFT-LCD display unit of measurement transducer electric current;

The method that a kind of improved Orthogonal correlation method the utility model proposes is measured ultrasonic transducer angle of impedance comprises the following steps:

Step 1: sensor gathers transducer both end voltage and flows through the current signal of transducer.

Step 2: modulate circuit 1 becomes the signal that can be received by analog to digital converter with modulate circuit 2 by the signal condition of sensor output.

Step 3: transducer voltage, current analog amount after analog to digital conversion convert digital quantity to, is beneficial to microprocessor ARM Cortex-M3 signal is directly carried out to correlation computations.

Step 4: introduce and the transducer voltage digital quantity relevant digital quantity that is orthogonal, this digital quantity is equivalent to transducer voltage digital quantity after discrete to right translation N ₀individual some gained, wherein:

N ₀＝[f _s/4f]。

Wherein, the frequency that f is sampled signal, the i.e. frequency of transducer voltage or current signal, f _sfor sample frequency, N ₀for integer.Due to, in actual cellular composite material ultrasonic cut process, the frequency f of transducer voltage, current signal is often drifted about, and causes f _snot integer always of/4f.Therefore, the voltage digital amount of introducing not always with the transducer voltage digital quantity relation that is orthogonal, at this moment have the deviation of an angle [alpha].

Orthogonal voltage digital amount and the transducer current digital quantity introduced are done to the correlation computations 1 that time constant equals 0, and result is as follows:

R_{{iu}_{2}} (0) = \frac{1}{N} Σ_{n = 0}^{N - 1} i (n) u_{2} (n) = \frac{UI}{2} \sin (θ_{U} - θ_{I}) .

Step 5: transducer voltage digital quantity and current digital amount are done respectively to the correlation computations 2 and 3 that time constant equals 0 and 1, the following formula of its operation result:

R_{iu} (0) = \frac{1}{N} Σ_{n = 0}^{N - 1} i (n) u (n) = \frac{UI}{2} \cos (θ_{U} - θ_{I});

R_{iu} (1) = \frac{1}{N} Σ_{n = 0}^{N - 1} i (n) u (n) = \frac{UI}{2} \cos (\frac{2 π f_{1}}{f_{s}} - θ_{U} - θ_{I});

Wherein, f ₁for transducer both end voltage in actual cellular composite material ultrasonic cut process and the frequency that flows through transducer current, f _sthe sample frequency providing for microprocessor ARM Cortex-M3 inside.

Step 6: obtain transducer both end voltage and the frequency f that flows through transducer current in actual cellular composite material ultrasonic cut process by correlation computations 2 and correlation computations 3 ₁, its result of calculation is as follows:

f_{1} = \frac{\arccos (\frac{2 R_{iu} (1)}{UI}) - \arccos (\frac{2 R_{iu} (0)}{UI})}{2 π} \times f_{s} .

Due to, in actual cellular composite material ultrasonic cut process, often due to reasons such as load, temperature, rigidity, corner wears, cause transducer both end voltage and the frequency that flows through transducer current to be drifted about, the quadrature voltage digital quantity that causes introducing not always with the transducer voltage digital quantity relation that is orthogonal, at this moment have the existence of a deviation α, by actual signal frequency f ₁the sample frequency f setting with microprocessor ARM Cortex-M3 inside _scan calculate angular deviation α, its result of calculation is as follows:

[f in formula _s/ 4f] represent the meaning that rounds.

Step 7: jointly calculate ultrasonic transducer impedance angle by correlation computations 1, correlation computations 2 and angular deviation α, its result of calculation is as follows:

θ = θ_{U} - θ_{I} = \arctan (\frac{\frac{R_{{iu}_{2}} (0)}{R_{iu} (0)} - \sin α}{\cos α}) .

Further, in order to prove that proposed a kind of improved Orthogonal correlation method measures the correctness of the device of ultrasonic transducer angle of impedance, the utility model calculates ultrasonic transducer angle of impedance for the Orthogonal correlation method before improving and after improving.

Suppose the superaudio signal that transducer both end voltage and the current signal that flows through transducer are 20KHz, its signal is respectively:

u(t)＝200sin(2π×20000t+π/3)；

i(t)＝3sin(2π×20000t)；

The amplitude that is transducer voltage, current signal is respectively 200V and 3A, and both phase differential are θ=π/3;

Consider in actual ultrasonic cut process, not 20KHz always of the frequency of transducer voltage, current signal, elect at random 20111Hz as therefore suppose signal frequency when emulation, under different sample frequency, the method of utilizing respectively MATLAB to measure ultrasonic transducer angle of impedance to the Orthogonal correlation method before and after improving is carried out simulating, verifying, and its simulation result is as follows:

As can be seen from the above table, adopt measuring accuracy that improved Orthogonal correlation method measures ultrasonic transducer angle of impedance apparently higher than the measuring accuracy before improving, and whether synchronize irrelevant with sampling, along with the raising of sample frequency, the actual signal frequency recording and angle of impedance precision have obviously and increase, but can't increase always, and sample frequency is too high, can affect equally the processing of data volume, be unfavorable for real-time.

Further, by ultrasonic transducer voltage, the current signal frequency of choosing a scope, improved Orthogonal correlation method angle of impedance is carried out to simulating, verifying.

Consider in actual cellular composite material ultrasonic cut process, a not fixed value always of transducer voltage, power frequency, its fluctuation size is without predictable, but disturbed by the factor such as load, temperature, rigidity of actual processing.Analyze for convenient, therefore suppose that transducer voltage, power frequency fluctuate within the scope of 25.0KHz at 19.5KHz, the sample frequency of considering real data collecting device is generally certain value, in order to obtain reflecting the signal of actual signal, and sampled data output can not be excessive, be 300KHz therefore get sample frequency.By MATLAB, the angle of impedance measuring method before and after improving is carried out to simulating, verifying, its simulation result as shown in Figure 4, known by curve map, angle of impedance measurement range before improvement changes within the scope of 60 °-61.4046 °, its variation range is 0-1.4 °, and angle of impedance measurement range after improving changes in 0-0.4 °, and while being directed to characteristic signals frequency, the measuring accuracy of the measuring accuracy after improvement before higher than improvement.

For a kind of improved Orthogonal correlation method that further checking the utility model proposes is measured the device of ultrasonic transducer angle of impedance and the practicality of new method, by building experiment porch, measure the cellular composite material Ultrasonic machining in resonant condition, when resonant condition, impedance angle equals 0 degree, in observing ultrasonic transducer voltage and current signal with oscillograph, utilize the mentioned device of the utility model, with different sample frequency, conditioning transducer voltage and current signal later gathered respectively, the final size that demonstrates impedance angle in LCD LCDs, its experimental result is as follows:

The utility model is 20.20KHz by the frequency of the ultrasonic transducer voltage and current signal of oscillograph gained, impedance angle is close to 0 degree, and utilize the mentioned a kind of improved Orthogonal correlation method of the utility model measure ultrasonic transducer angle of impedance device and method gained data as shown above, find by contrast, transducer impedance angle measuring method measuring accuracy after improvement apparently higher than improve before, and be directed to different sample frequency, the measuring accuracy difference obtaining.

Claims

1. Orthogonal correlation method is measured a device for ultrasonic transducer angle of impedance, and this device comprises the voltage sensor of measurement transducer voltage, current sensor, the first modulate circuit, the second modulate circuit, ARM Cortex-M3 microprocessor and the TFT-LCD display unit of measurement transducer electric current;

It is characterized in that: voltage sensor is connected by Du Pont's line with the first modulate circuit signal input interface, and current sensor is connected by Du Pont's line with the second modulate circuit; The signal output interface of the first modulate circuit is connected with an analog to digital converter input port of ARM Cortex-M3 microprocessor internal by Du Pont's line; The signal output interface of the second modulate circuit is connected with another analog to digital converter input port of ARM Cortex-M3 microprocessor internal by Du Pont's line; Voltage sensor connects 15V power supply, connect+5V of current sensor power supply, connect+5V of the first modulate circuit power supply, connect+5V of the second modulate circuit power supply; Connect+5V of ARM Cortex-M3 microprocessor power supply, ARM Cortex-M3 microprocessor is connected by 8060 buses with TFT-LCD display screen;