CN116952293A - Application performance test method of PZT-based flexible piezoelectric sensor - Google Patents
Application performance test method of PZT-based flexible piezoelectric sensor Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 36
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- 238000012360 testing method Methods 0.000 claims abstract description 142
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- 230000035945 sensitivity Effects 0.000 claims abstract description 20
- 238000012512 characterization method Methods 0.000 claims abstract description 13
- 238000010998 test method Methods 0.000 claims abstract description 8
- 230000000694 effects Effects 0.000 claims abstract description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 43
- 230000005284 excitation Effects 0.000 claims description 16
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- 238000004804 winding Methods 0.000 claims description 8
- 210000000707 wrist Anatomy 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 3
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- 210000002321 radial artery Anatomy 0.000 claims description 3
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- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 101
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- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
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- G—PHYSICS
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
- G01H11/08—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means using piezoelectric devices
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- G—PHYSICS
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
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Abstract
The application provides an application performance test method of a PZT-based flexible piezoelectric sensor, which is characterized by comprising the following steps of: building a sensor test platform, performing sensor performance characterization test, motion state identification test and transformer vibration monitoring test on the PZT-based flexible piezoelectric sensor, and obtaining performance parameters of the PZT-based flexible piezoelectric sensor on each application surface; the sensor performance characterization test comprises a true and false signal judgment test, a dynamic response test, a sensitivity test, a linearity test, a response time test and a durability test; according to the test data obtained in the sensor performance characterization test, the performance data of the PZT-based flexible piezoelectric sensor are obtained through statistics; judging whether to perform a motion state identification test according to the performance data; the exercise state identification test comprises a bending state identification test and a pulse signal monitoring test. The application has the beneficial effects that: the test method has the effects of comprehensiveness, accuracy, high efficiency, reliability and stability.
Description
Technical Field
The application belongs to the field of performance test, and particularly relates to an application performance test method of a PZT-based flexible piezoelectric sensor.
Background
With the continuous development of science and technology, PZT-based flexible piezoelectric sensors are receiving attention in various fields, such as health monitoring, robotics, smart wearable devices, and the like. Among them, PZT (lead zirconium titanate) -based PZT-based flexible piezoelectric sensors are favored for their good piezoelectric performance, flexibility and stability. However, in practical applications, performance evaluation and optimization of PZT-based flexible piezoelectric sensors are critical, and therefore, it is very necessary to develop a comprehensive, accurate, and efficient application performance test method.
In the prior art, the performance test method for the PZT-based flexible piezoelectric sensor is generally simpler and one-sided, and the performance of the sensor in various application fields is difficult to comprehensively evaluate. In addition, the existing testing method is complex in operation, long in time consumption and high in testing cost, and all factors limit performance and application value of the PZT-based flexible piezoelectric sensor in practical application.
Disclosure of Invention
In view of the foregoing, the present application aims to provide a method for testing application performance of a PZT-based flexible piezoelectric sensor, so as to solve at least one of the above-mentioned technical problems.
In order to achieve the above purpose, the technical scheme of the application is realized as follows:
the application performance test method of the PZT-based flexible piezoelectric sensor comprises the steps of building a sensor test platform, performing a sensor performance characterization test, a motion state identification test and a transformer vibration monitoring test on the PZT-based flexible piezoelectric sensor, and obtaining performance parameters of the PZT-based flexible piezoelectric sensor on each application surface;
the sensor performance characterization test comprises a true and false signal judgment test, a dynamic response test, a sensitivity test, a linearity test, a response time test and a durability test;
according to the test data obtained in the sensor performance characterization test, the performance data of the PZT-based flexible piezoelectric sensor are obtained through statistics;
judging whether to perform a motion state identification test according to the performance data;
the exercise state identification test comprises a bending state identification test and a pulse signal monitoring test.
Further, the device forming the sensor test platform comprises a signal generator, a power amplifier, a vibration exciter, a signal acquisition card and a signal analysis system;
the signal generator generates electric signals with different waveforms, different frequencies and different amplitudes to simulate different excitation conditions;
the power amplifier amplifies the electric signal generated by the signal generator to a required power level according to the requirement of the vibration exciter, and drives the vibration exciter to generate mechanical vibration meeting the test condition;
the vibration exciter converts the electric signal into mechanical vibration, and applies periodic pressure to the piezoelectric sensor to enable the piezoelectric sensor to generate a charge signal;
the signal acquisition card detects and collects the charge signals output by the sensor, converts the charge signals into digital signals and transmits the digital signals to the central control computer;
the signal analysis system processes and analyzes the acquired digital signals, calculates the performance parameters of the PZT-based flexible piezoelectric sensor, and controls and monitors the testing process.
Further, the true and false signal determination test process is as follows:
and sealing the PZT-based flexible piezoelectric sensor by using an insulating adhesive tape to isolate the influence of external factors on the output voltage signal of the sensor, leading out a lead from the sensor to be connected with an external circuit, carrying out a positive-negative connection experiment on the positive electrode and the negative electrode which are in exchange connection, measuring the voltage output signal value of the PZT-based flexible piezoelectric sensor before and after the positive electrode and the negative electrode are connected in a reverse way, and outputting an electric signal by the PZT-based flexible piezoelectric sensor to be true if the absolute values of the output voltages of the sensors are equal but the directions are opposite.
Further, the dynamic response test procedure is as follows
Selecting a sinusoidal pressure signal as an input signal, setting parameters of a signal generator according to the amplitude, frequency and phase of the signal;
connecting an output signal of the signal generator to a power amplifier through a wire, and connecting the output signal of the power amplifier to a vibration exciter;
the vibration exciter generates a sinusoidal pressure signal and applies the sinusoidal pressure signal to the PZT-based flexible piezoelectric sensor, the PZT-based flexible piezoelectric sensor generates deformation and converts the deformation into a voltage signal based on a piezoelectric effect;
and the signal acquisition card transmits the voltage output signal of the PZT-based flexible piezoelectric sensor to the signal analysis system, and processes and analyzes the voltage output signal.
Further, according to the data of the PZT-based flexible piezoelectric sensor in the signal analysis system, the following calculation is performed:
calculating to obtain a sensitivity test result of the PZT-based flexible piezoelectric sensor through the peak voltage values of the PZT-based flexible piezoelectric sensor under different loads and the data of the applied loads;
calculating to obtain a linearity test result of the PZT-based flexible piezoelectric sensor through the output voltage value of the PZT-based flexible piezoelectric sensor and the pressure value born by the PZT-based flexible piezoelectric sensor;
and calculating a measuring point through data from a minimum value to a peak value in an output voltage waveform of the PZT-based flexible piezoelectric sensor to obtain a response time test result of the PZT-based flexible piezoelectric sensor.
Further, the durability test procedure is as follows:
setting a test environment required by durability test, wherein the temperature is indoor temperature, the load is 7N and 1HZ, and the test time is one week;
applying a cyclic load to the PZT-based flexible piezoelectric sensor in a circle, and performing output voltage test for 30 minutes to obtain a waveform chart of an output signal of the PZT-based flexible piezoelectric sensor;
if the waveform of the output signal of the sensor at the tail position of the waveform diagram is clear, and the peak value of the output voltage has small range fluctuation, but the peak value is unchanged, the PZT-based flexible piezoelectric sensor is judged to pass the durability test.
Further, the bending state identification test is as follows:
attaching a PZT-based flexible piezoelectric sensor to the bent part of the arm of a tester, leading out conductive spinning cloth from an electrode to be connected with a contact of a signal collector, and attaching an insulating tape around the PZT-based flexible piezoelectric sensor;
the tester moves the arm, and the PZT-based flexible piezoelectric sensor makes continuous actions of bending and straightening along with the arm of the tester;
identifying the real-time motion state of the arm by detecting the output voltage peak value of the PZT-based flexible piezoelectric sensor;
if the output voltage peak value of the PZT-based flexible piezoelectric sensor is obviously improved along with gradual bending of the arms of the testers, the PZT-based flexible piezoelectric sensor passes the bending state identification test.
Further, the pulse signal monitoring test is as follows:
fixing the sensor at the radial artery of the wrist of the tester, lightly placing the palm of the hand to be tested on the keyboard by the tester, and pressing different key positions of the keyboard according to a rule for eight times;
recording output waveforms of the PZT-based flexible piezoelectric sensor when a tester presses different key positions, and if the output waveforms of the PZT-based flexible piezoelectric sensor are obviously differentiated when the tester presses different key positions, identifying and testing the PZT-based flexible piezoelectric sensor through a bending state.
Further, the process of the transformer vibration monitoring test is as follows:
selecting iron cores with the same size and respectively made of amorphous alloy and ultrathin oriented silicon steel, winding a winding on the iron cores, and pasting a PZT-based flexible piezoelectric sensor on the surfaces of the iron cores;
different excitation conditions are simulated by applying different voltages to the windings, and the vibration condition of the iron core under the different excitation conditions is recorded, so that a transformer vibration monitoring test result is obtained;
if the PZT-based flexible piezoelectric sensor still can detect obvious vibration on the surface of the iron core of the ultrathin oriented silicon steel, the PZT-based flexible piezoelectric sensor monitors and tests through transformer vibration.
Compared with the prior art, the application performance testing method of the PZT-based flexible piezoelectric sensor has the following beneficial effects:
compared with the prior art, the technical scheme provided by the application has the following technical advantages:
comprehensively: the system tests the performance of the sensor in aspects of performance characterization, motion state identification, transformer vibration monitoring and the like systematically, and realizes comprehensive evaluation of the PZT-based flexible piezoelectric sensor.
Accuracy: according to the scheme, the performance of the sensor can be accurately estimated through a plurality of test methods such as a true and false signal judging test, a dynamic response test, a sensitivity test, a linearity test, a response time test, a durability test and the like, and powerful support is provided for optimal design and application.
High efficiency: the testing method is simple and convenient to operate, reduces testing cost and time, improves testing efficiency, and is beneficial to popularization of practical application.
Reliability and stability: through the movement state identification test, the reliability and stability of the sensor in different movement states are ensured, and the application range of the PZT-based flexible piezoelectric sensor is expanded.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:
FIG. 1 is a flow chart of a method for testing application performance of a PZT-based flexible piezoelectric sensor according to an embodiment of the present application;
FIG. 2 is a schematic diagram of an electrode forward and reverse connection experiment according to an embodiment of the present application;
FIG. 3 is a schematic diagram of the positive and negative voltage output signals of the electrodes according to the embodiment of the application;
FIG. 4 is a schematic diagram of the output voltage values of the sensor under different loads according to an embodiment of the present application;
FIG. 5 is a schematic diagram of the output of a conventional sensor and PZT-based flexible piezoelectric sensor according to an embodiment of the present application;
FIG. 6 is a schematic diagram of the output peak voltage at load 0-11N according to an embodiment of the present application;
FIG. 7 is a graph showing a fitted curve of the output peak voltage according to an embodiment of the present application;
FIG. 8 is a schematic diagram of response time of a sensor according to an embodiment of the application;
FIG. 9 is a schematic diagram of durability test data according to an embodiment of the present application;
FIG. 10 is a schematic diagram illustrating a pulse signal monitoring test according to an embodiment of the present application;
FIG. 11 is a diagram showing dynamic signals of different fingers inputting letters according to an embodiment of the present application;
fig. 12 is a schematic structural diagram of an iron core model according to an embodiment of the present application;
fig. 13 is a schematic diagram of vibration detection results of amorphous alloy iron cores under different excitation according to an embodiment of the present application;
fig. 14 is a schematic diagram of vibration detection results of ultrathin oriented silicon steel cores under different excitation according to an embodiment of the application.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other.
The application will be described in detail below with reference to the drawings in connection with embodiments.
The application performance test method of the PZT-based flexible piezoelectric sensor comprises the steps of building a sensor test platform, performing sensor performance characterization test, motion state identification test and transformer vibration monitoring test on the PZT-based flexible piezoelectric sensor, and obtaining performance parameters of the PZT-based flexible piezoelectric sensor on each application surface;
the sensor performance characterization test comprises a true and false signal judgment test, a dynamic response test, a sensitivity test, a linearity test, a response time test and a durability test;
according to the test data obtained in the sensor performance characterization test, the performance data of the PZT-based flexible piezoelectric sensor are obtained through statistics;
judging whether to perform a motion state identification test according to the performance data;
the exercise state identification test comprises a bending state identification test and a pulse signal monitoring test.
The device for forming the sensor test platform comprises a signal generator, a power amplifier, a vibration exciter, a signal acquisition card and a signal analysis system;
a signal generator: generating electrical signals of different waveforms (such as sine waves, square waves, triangular waves and the like), different frequencies (such as 1Hz, 10Hz, 100Hz and the like) and different amplitudes (such as 1V, 10V, 100V and the like) can be used for simulating different excitation conditions;
the power amplifier amplifies the electric signal generated by the signal generator to a required power level according to the requirement of the vibration exciter, and drives the vibration exciter to generate mechanical vibration meeting the test condition;
the vibration exciter converts the electric signal into mechanical vibration, applies periodic pressure to the piezoelectric sensor to enable the piezoelectric sensor to generate charge signals, and has different types, such as electromagnetic type, piezoelectric type and pneumatic type, and different working principles and characteristics;
the signal acquisition card detects and collects the charge signals output by the sensor, converts the charge signals into digital signals, transmits the digital signals to the central control computer, and can condition the signals, such as amplification, filtering and the like, so as to improve the signal quality and accuracy;
the signal analysis system processes and analyzes the acquired digital signals, calculates the performance parameters of the PZT-based flexible piezoelectric sensor, controls and monitors the testing process, and can also control and monitor the testing process so as to ensure the effectiveness and reliability of the test.
When the PZT-based flexible piezoelectric sensor deforms, voltage and current output signals can be generated, but experiments are required to be designed to test whether the output electric signals are true or false, namely whether the electric signals generated by the sensor are completely obtained by the piezoelectric effect of the piezoelectric element, but not electromagnetic interference or capacitance and friction power generation of the sensor in a natural environment.
The true and false signal judging and testing process is as follows:
as shown in fig. 2: and sealing the PZT-based flexible piezoelectric sensor by using an insulating tape to ensure that the output voltage signal of the sensor is not influenced by external factors, connecting a lead led out from the sensor with an external circuit, performing a positive and negative connection experiment, measuring the voltage output signal values of the PZT-based flexible piezoelectric sensor before and after the positive and negative connection of the electrodes, and determining that the output electric signal of the PZT-based flexible piezoelectric sensor is true if the absolute values of the output voltages of the sensors are equal but the directions are opposite.
As shown in FIG. 3, under the same experimental environment and excitation condition, the voltage signal values obtained by the positive electrode and the negative electrode of the PZT-based flexible piezoelectric sensor are basically equal, and the extreme value is between 4 and 6V. The voltage amplitude fluctuates but the voltage waveforms obtained by different wiring modes are opposite. The positive and negative connection experiments of the sensor electrodes prove that: the electrical signal generated by the PZT-based flexible piezoelectric sensor upon deformation comes from the piezoelectricity of the material itself.
After the voltage output signal of the PZT-based flexible piezoelectric sensor is determined to be completely obtained by the piezoelectric effect of the material, the design experiment further tests the performance of the PZT-based flexible piezoelectric sensor under different loads.
The dynamic response test procedure is as follows
In order to test the output characteristics of the PZT-based flexible piezoelectric sensor under dynamic pressure, a sinusoidal pressure signal is selected as an input signal;
first, parameters of the signal generator, including amplitude, frequency and phase of the signal, are set. Then, the output signal of the signal generator is connected to the power amplifier through a wire so as to increase the strength of the signal, and then the output signal of the power amplifier is connected to the vibration exciter;
when the vibration exciter receives an input signal, the vibration exciter generates a sine pressure signal with the same frequency and phase as the input signal and applies the sine pressure signal to the PZT-based flexible piezoelectric sensor contacted with the sine pressure signal;
when the PZT-based flexible piezoelectric sensor is affected by vibration transmitted by the vibration exciter, the PZT-based flexible piezoelectric sensor generates corresponding deformation and converts the deformation into a voltage signal based on a piezoelectric effect;
the signal acquisition card transmits a voltage output signal of the PZT-based flexible piezoelectric sensor to the computer;
the signal analysis system on the computer can display and record the voltage signals generated by the sensors under different frequencies and different pressures, and further process and analyze the voltage signals.
According to the working environment of the existing PZT-based flexible piezoelectric sensor in practical application, a load pressure range threshold is set to be 0.5N-9.5N, whether the PZT-based flexible piezoelectric sensor to be tested passes a dynamic response test is judged according to the results obtained through processing and analysis of a signal analysis system, if the output voltage of the PZT-based flexible piezoelectric sensor to be tested still can be changed stably under the conditions that the load pressure is lower than 0.5N and the load pressure is higher than 9.5N, the working range of the PZT-based flexible piezoelectric sensor to be tested is considered to meet the required working requirement range, namely the PZT-based flexible piezoelectric sensor passes the dynamic response test.
The frequency of the applied load was set to 1Hz, the load was gradually increased from 0.1N, and the output voltage values of the sensors under different loads were observed.
The experimental frequency is selected to be 1Hz, so that the piezoelectric potential is not completely derived after the load is applied to the sensor due to the excessive frequency.
As shown in fig. 4: when the load is 0.1N, the output voltage value of the sensor is 0.1V, and the output voltage is increased along with the increase of the load borne by the sensor, so that when the load is gradually increased from 0.5N to 7N, the peak value of the output voltage is rapidly increased from 0.55N to 7.25N, and when the load is increased from 7N to 11N, the output voltage of the sensor is accelerated slowly, namely the peak value of the output voltage of the sensor is basically not obviously changed after the load exceeds 7N, the output voltage limit of the sensor is reached, and the normal use requirement of the piezoelectric sensor can be met. The normal use basis of the sensor is satisfied, namely, the following indexes are used for measurement. Such as linear relationship: between the load range 0.1N and 7N, the sensor output voltage exhibits a good linear relationship with the load, meaning that within this range the sensor is able to accurately detect and react to load changes.
Output voltage peak: when the load increases to 7N, the peak output voltage of the sensor does not substantially change any more although the sensor output voltage increases slowly, which means that the sensor is operating stably in the resulting load range.
Wide working range: experimental results show that the sensor can work normally in the load range of 0.1N to 7N. This shows that the sensor has wider working range, can satisfy the demand of different application scenes.
In summary, the PZT-based flexible piezoelectric sensor has good output characteristics, high sensitivity, stability and a wider working range, so that the normal use requirement of the piezoelectric sensor can be met. )
As shown in fig. 4 and 5, it can be seen that the peak value of the output voltage of the conventional PVDF sensor at 1Hz and 2N is only about 1.38V, and the peak value of the voltage of the prepared PZT-based flexible piezoelectric sensor is about 2.3V, the output voltage is increased by 1.67 times, and the voltage increase factor is continuously increased as the volume fraction of PZT particles in the sensor increases.
According to the data of the PZT-based flexible piezoelectric sensor in the signal analysis system, the following calculation is performed:
the piezoelectric sensor with high sensitivity, high frequency response, high precision, portability and simplicity has important significance in detecting human motion gestures and monitoring equipment operation, so that other performance parameters of the piezoelectric sensor are further explored, and experimental tests are designed on the sensitivity, linearity, response time and the like of the sensor.
The sensitivity of a piezoelectric sensor, i.e., the ratio of output voltage to input force or pressure, is a value reflecting the ability of the sensor to convert the stress to an electrical signal, typically expressed in volts/newton (V/N) or volts/pascal (V/Pa), and it is important to develop a precision sensor to increase the sensitivity of a piezoelectric sensor.
As shown in fig. 6: analyzing the data obtained by the dynamic response experiment, and importing numerical calculation software to analyze and calculate by recording the peak voltage under different loads and the data of the applied load.
According to the working environment of the existing PZT-based flexible piezoelectric sensor in practical application, a sensitivity test threshold is set to be 1V/N, a load pressure range is a PZT-based flexible piezoelectric sensor response range obtained in dynamic response test, whether the PZT-based flexible piezoelectric sensor to be tested passes the sensitivity test is judged according to a sensitivity test result, and if the output voltage of the sensor to be tested can be increased rapidly along with load increase in the response range, the sensor passes the sensitivity test.
As shown in fig. 7: when the load is 0-6N, the output voltage of the sensor and the load are linearly increased, the sensitivity is calculated to be 1.19V/N, and when the load is more than 7N, the sensor output voltage is gradually saturated due to the limitations of the piezoelectric material of the sensor and the thickness, namely, the output voltage is basically unchanged along with the increase of the load.
Between the load range of 0.1N and 7N, the output voltage of the sensor increases rapidly with increasing load. This means that the sensor has a high sensitivity to load changes and can accurately detect load changes in practical applications.
The linearity of a piezoelectric sensor, i.e. whether the output voltage is proportional to the input force or pressure, is generally expressed by an error percentage or a linear fitting coefficient, the linearity is generally defined as the degree to which the line segment of the load and voltage output of the piezoelectric sensor can approach a straight line in a specific working range, the higher the linear fitting degree of the piezoelectric sensor, the more accurate the result output by the piezoelectric sensor is, which is not influenced by the environment or other factors, and the output value can reflect the actual force or pressure change.
According to the working environment of the traditional PZT-based flexible piezoelectric sensor in practical application, a linearity range threshold value is set to be 1+/-0.005, and if the fitted curve value between the output voltage peak value and the load pressure of the tested PZT-based flexible piezoelectric sensor in the load range is within the linearity range threshold value, the sensor passes a linearity test.
The load is within 0-6N, the output peak voltage and the load are in a linear relation, and the fitting coefficient of the fitting curve is 0.9962, so that the sensor is highly fitted in the working stress range, and the response of the sensor is more accurate and reliable. The fitted expression is obtained as:
y (U) ＝a×x (F) +b
wherein U is the output peak voltage of the sensor, and F is the external load. The method comprises the following steps of calculating and solving through numerical software: a=1.191 and b=0.025. Where a is also the sensitivity value of the piezoelectric sensor.
As shown in fig. 8: for the piezoelectric sensor, the response time is one of important indexes reflecting the output performance, the response time threshold is set to be 100ms according to the working environment of the traditional PZT-based flexible piezoelectric sensor in practical application, and if the response time of the tested sensor is lower than the response time threshold, the sensor passes the response time test.
And (3) carrying out sensor response time experiments under the loads of 1Hz and 5N, intercepting and amplifying a section from a minimum value to a peak value in the output voltage waveform, and calculating a measuring point to obtain the response time of the PZT-based flexible piezoelectric sensor as 58ms.
The durability test procedure was as follows:
as shown in fig. 9: setting a test environment required by durability test, wherein the temperature is indoor temperature, the load is 7N and 1HZ, and the test time is one week;
applying a cyclic load to the PZT-based flexible piezoelectric sensor in a circle, and performing output voltage test for 30 minutes to obtain a waveform chart of an output signal of the PZT-based flexible piezoelectric sensor;
if the waveform of the output signal of the sensor at the tail position of the waveform diagram is clear, and the peak value of the output voltage has small range fluctuation, but the peak value is unchanged, the PZT-based flexible piezoelectric sensor is judged to pass the durability test.
Counting test results in the true and false signal judging test, the dynamic response test, the sensitivity test, the linearity test, the response time test and the durability test, and if the PZT-based flexible piezoelectric sensor passes all the tests, carrying out a bending state identification test, a pulse signal monitoring test and a transformer vibration monitoring test on the PZT-based flexible piezoelectric sensor; otherwise, the PZT-based flexible piezoelectric sensor does not meet the product specification.
The bending state identification test is performed as follows:
attaching a PZT-based flexible piezoelectric sensor to the bent part of the arm of a tester, leading out conductive spinning cloth from an electrode to be connected with a contact of a signal collector, and attaching an insulating tape around the PZT-based flexible piezoelectric sensor;
the tester moves the arm, and the PZT-based flexible piezoelectric sensor makes continuous actions of bending and straightening along with the arm of the tester;
and identifying the real-time motion state of the arm by detecting the output voltage peak value of the PZT-based flexible piezoelectric sensor.
As shown in fig. 10: in a bending/straightening test, when the state of an arm is straight, the sensor can generate a noise voltage signal of about 60mV at most, and as the state of the arm is straight to bent, the PZT-based flexible piezoelectric sensor generates a voltage response and starts to output a voltage signal;
the peak value of the output voltage signal increases along with the increase of the bending angle of the arm, the peak value of the output voltage is different under different bending degrees of the arm, and the maximum voltage output signal value generated by the sensor is 4.25V.
The pulse signal monitoring test process is as follows:
as shown in fig. 11: fixing the sensor at the radial artery of the wrist of the tester, lightly placing the palm of the hand to be tested on the keyboard by the tester, and pressing different key positions of the keyboard according to a rule for eight times;
recording output waveforms of the PZT-based flexible piezoelectric sensor when a tester presses different key positions, and obtaining a pulse signal monitoring test result according to whether the differentiation of the output waveforms is obvious or not;
specifically, wrist pulse vibration is measured through the sensor, different key positions are pressed, different pulse vibration can be caused, and therefore the consideration standard of the waveform is as follows: the voltage waveforms generated by different key presses need to be clearly distinguishable differently, i.e. the two waveforms are not identical. And secondly, whether the waveform is regular or not is observed, errors are avoided, and the judging accuracy is ensured.
When the transformer operates, the magnetostriction effect can cause resonance phenomenon of the internal structure, so that the amplitude is overlarge, and further the problems of damage of an iron core of the transformer, loosening deformation of a winding, overlarge noise and the like can be caused, and the vibration monitoring of the transformer can prevent the costly downtime and keep the flow to operate stably; the overall safety can also be improved by early finding out dangerous situations; by monitoring the healthy running state of the power transformer in real time, the running safety, stability and reliability of the transformer can be improved.
Two kinds of iron cores with different materials and the same size are selected, windings are wound on the iron cores, different excitation conditions are respectively applied to simulate the vibration of the transformer under the actual working condition, and the iron core materials are selected from amorphous alloy and ultrathin oriented silicon steel.
The structure of the core model is shown in fig. 12: in the figure, the letter corresponds to the design parameter of the iron core, a is the stacking thickness of the iron core, b is the width of a window, c is the width of the window, R is the radius of a serial port fillet and the like; wherein the effective sectional area of the iron core is Ac, the area of the iron core window is Aw, the area of the iron core AwAc, the length of the magnetic circuit is Lm, and the main parameters of the iron core are shown in the following figures:
| design parameters | Parameter value | Design parameters | Parameter value |
| Iron core stacking thickness a/mm | 8±0.5 | Iron core window width b/mm | 20 |
| Iron core window height c/mm | 54 | Iron core height d/mm | 40±1 |
| Iron core width e/mm | 36±1 | Length f/mm of iron core | 70±2 |
| Window fillet radius R/mm | 2 | Magnetic path length Lm/cm | 17 |
| Effective sectional area Ac/cm of iron core 2 | 2.79 | Iron core window area Aw/cm 2 | 10.8 |
| Iron core area AwAc/cm 4 | 30.1 |
。
The reason for selecting amorphous alloy and ultrathin oriented silicon steel is as follows: the amorphous alloy iron core has obvious vibration under the power frequency excitation, is used for testing whether the PZT-based flexible piezoelectric sensor can detect an iron core vibration signal under low frequency, the ultrathin oriented silicon steel iron core material performance is excellent, the iron core basically has no obvious vibration under a few kilohertz, and the vibration detection performance of the sensor under high frequency is tested.
The vibration of the iron core is mainly caused by magnetostriction of materials after excitation is applied, and the excitation is simulated differently by using different applied voltages in experiments.
As shown in fig. 13: the 50Hz amorphous alloy iron cores are respectively excited by 0.1T, 0.3T and 0.5T, and the vibration signals generated by the amorphous alloy after different excitation are obviously detected by the sensor, so that the voltage waveform output by the sensor is good.
The amorphous alloy iron core vibrates more obviously, the PZT-based flexible piezoelectric sensor can obviously detect the vibration condition of the iron core, so that an ultra-thin oriented silicon steel material iron core vibration experiment is increased, the iron core of the ultra-thin oriented silicon steel material hardly vibrates under low frequency, the frequency applied to the iron core in practical research is usually more than kilohertz, the initial excitation conditions of 0.5T, 0.8T and 1.0T under 1kHz are set, and the existence of a voltage signal output of the sensor is tested;
as shown in fig. 14, it can be seen from the graph that the vibration of the ultra-thin oriented silicon steel core at high frequency is not obvious, but the sensor can still detect the slight vibration of the core and output a better voltage waveform.
The vibration experiments of iron cores made of different materials prove that the PZT-based flexible piezoelectric sensor can be applied to vibration monitoring of a transformer, the flexibility of the PZT-based flexible piezoelectric sensor can be applied to wider and complex scenes, the piezoelectric performance of the PZT-based flexible piezoelectric sensor is superior to that of the traditional PZT-based flexible piezoelectric sensor, and the analysis and research on the output voltage signals of the sensor can provide possibility for the structural optimization design of electrical equipment.
Those of ordinary skill in the art will appreciate that the elements and method steps of each example described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the elements and steps of each example have been described generally in terms of functionality in the foregoing description to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the several embodiments provided in the present application, it should be understood that the disclosed methods and systems may be implemented in other ways. For example, the above-described division of units is merely a logical function division, and there may be another division manner when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted or not performed. The units may or may not be physically separate, and components shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment of the present application.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and are intended to be included within the scope of the appended claims and description.
The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the application.
Claims (9)
1. A method for testing application performance of a PZT-based flexible piezoelectric sensor is characterized by comprising the following steps of:
building a sensor test platform, performing sensor performance characterization test, motion state identification test and transformer vibration monitoring test on the PZT-based flexible piezoelectric sensor, and obtaining performance parameters of the PZT-based flexible piezoelectric sensor on each application surface;
the sensor performance characterization test comprises a true and false signal judgment test, a dynamic response test, a sensitivity test, a linearity test, a response time test and a durability test;
according to the test data obtained in the sensor performance characterization test, the performance data of the PZT-based flexible piezoelectric sensor are obtained through statistics;
judging whether to perform a motion state identification test according to the performance data;
the exercise state identification test comprises a bending state identification test and a pulse signal monitoring test.
2. The application performance test method of the PZT-based flexible piezoelectric sensor according to claim 1, wherein:
the device for forming the sensor test platform comprises a signal generator, a power amplifier, a vibration exciter, a signal acquisition card and a signal analysis system;
the signal generator generates electric signals with different waveforms, different frequencies and different amplitudes to simulate different excitation conditions;
the power amplifier amplifies the electric signal generated by the signal generator to a required power level according to the requirement of the vibration exciter, and drives the vibration exciter to generate mechanical vibration meeting the test condition;
the vibration exciter converts the electric signal into mechanical vibration, and applies periodic pressure to the piezoelectric sensor to enable the piezoelectric sensor to generate a charge signal;
the signal acquisition card detects and collects the charge signals output by the sensor, converts the charge signals into digital signals and transmits the digital signals to the central control computer;
the signal analysis system processes and analyzes the acquired digital signals, calculates the performance parameters of the PZT-based flexible piezoelectric sensor, and controls and monitors the testing process.
3. The application performance test method of the PZT-based flexible piezoelectric sensor according to claim 1, wherein:
the true and false signal judging and testing process is as follows:
and sealing the PZT-based flexible piezoelectric sensor by using an insulating adhesive tape to isolate the influence of external factors on the output voltage signal of the sensor, leading out a lead from the sensor to be connected with an external circuit, carrying out a positive-negative connection experiment on the positive electrode and the negative electrode which are in exchange connection, measuring the voltage output signal value of the PZT-based flexible piezoelectric sensor before and after the positive electrode and the negative electrode are connected in a reverse way, and outputting an electric signal by the PZT-based flexible piezoelectric sensor to be true if the absolute values of the output voltages of the sensors are equal but the directions are opposite.
4. The application performance test method of the PZT-based flexible piezoelectric sensor according to claim 2, wherein:
the dynamic response test procedure is as follows
Selecting a sinusoidal pressure signal as an input signal, setting parameters of a signal generator according to the amplitude, frequency and phase of the signal;
connecting an output signal of the signal generator to a power amplifier through a wire, and connecting the output signal of the power amplifier to a vibration exciter;
the vibration exciter generates a sinusoidal pressure signal and applies the sinusoidal pressure signal to the PZT-based flexible piezoelectric sensor, the PZT-based flexible piezoelectric sensor generates deformation and converts the deformation into a voltage signal based on a piezoelectric effect;
and the signal acquisition card transmits the voltage output signal of the PZT-based flexible piezoelectric sensor to the signal analysis system, and processes and analyzes the voltage output signal.
5. The application performance test method for the PZT-based flexible piezoelectric sensor according to claim 4, wherein:
according to the data of the PZT-based flexible piezoelectric sensor in the signal analysis system, the following calculation is performed:
calculating to obtain a sensitivity test result of the PZT-based flexible piezoelectric sensor through the peak voltage values of the PZT-based flexible piezoelectric sensor under different loads and the data of the applied loads;
calculating to obtain a linearity test result of the PZT-based flexible piezoelectric sensor through the output voltage value of the PZT-based flexible piezoelectric sensor and the pressure value born by the PZT-based flexible piezoelectric sensor;
and calculating a measuring point through data from a minimum value to a peak value in an output voltage waveform of the PZT-based flexible piezoelectric sensor to obtain a response time test result of the PZT-based flexible piezoelectric sensor.
6. The application performance test method of the PZT-based flexible piezoelectric sensor according to claim 1, wherein:
the durability test procedure was as follows:
setting a test environment required by durability test, wherein the temperature is indoor temperature, the load is 7N and 1HZ, and the test time is one week;
applying a cyclic load to the PZT-based flexible piezoelectric sensor in a circle, and performing output voltage test for 30 minutes to obtain a waveform chart of an output signal of the PZT-based flexible piezoelectric sensor;
if the waveform of the output signal of the sensor at the tail position of the waveform diagram is clear, and the peak value of the output voltage has small range fluctuation, but the peak value is unchanged, the PZT-based flexible piezoelectric sensor is judged to pass the durability test.
7. The application performance test method of the PZT-based flexible piezoelectric sensor according to claim 1, wherein:
the bending state identification test is performed as follows:
attaching a PZT-based flexible piezoelectric sensor to the bent part of the arm of a tester, leading out conductive spinning cloth from an electrode to be connected with a contact of a signal collector, and attaching an insulating tape around the PZT-based flexible piezoelectric sensor;
the tester moves the arm, and the PZT-based flexible piezoelectric sensor makes continuous actions of bending and straightening along with the arm of the tester;
identifying the real-time motion state of the arm by detecting the output voltage peak value of the PZT-based flexible piezoelectric sensor;
if the output voltage peak value of the PZT-based flexible piezoelectric sensor is obviously improved along with gradual bending of the arms of the testers, the PZT-based flexible piezoelectric sensor passes the bending state identification test.
8. The application performance test method of the PZT-based flexible piezoelectric sensor according to claim 1, wherein:
the pulse signal monitoring test process is as follows:
fixing the sensor at the radial artery of the wrist of the tester, lightly placing the palm of the hand to be tested on the keyboard by the tester, and pressing different key positions of the keyboard according to a rule for eight times;
recording output waveforms of the PZT-based flexible piezoelectric sensor when a tester presses different key positions, and if the output waveforms of the PZT-based flexible piezoelectric sensor are obviously differentiated when the tester presses different key positions, identifying and testing the PZT-based flexible piezoelectric sensor through a bending state.
9. The application performance test method of the PZT-based flexible piezoelectric sensor according to claim 1, wherein:
the process of the transformer vibration monitoring test is as follows:
selecting iron cores with the same size and respectively made of amorphous alloy and ultrathin oriented silicon steel, winding a winding on the iron cores, and pasting a PZT-based flexible piezoelectric sensor on the surfaces of the iron cores;
different excitation conditions are simulated by applying different voltages to the windings, and the vibration condition of the iron core under the different excitation conditions is recorded, so that a transformer vibration monitoring test result is obtained;
if the PZT-based flexible piezoelectric sensor still can detect obvious vibration on the surface of the iron core of the ultrathin oriented silicon steel, the PZT-based flexible piezoelectric sensor monitors and tests through transformer vibration.
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