阅读说明：本技术 一种压电测量装置 (Piezoelectric measuring device ) 是由 方辉 于 2021-08-09 设计创作，主要内容包括：本发明涉及一种压电测量装置,包括主控模块、信号输入模块、驱动波形生成模块和锁相环模块；信号输入模块,用于采集动态力传感信号并传输至锁相环模块和主控模块；驱动波形生成模块,用于根据主控模块的振荡驱动指令产生驱动波形信号,并传输至锁相环模块和外设的振荡驱动接口；锁相环模块,用于实时检测动态力传感信号和驱动波形信号之间的相位差,并锁定相位差,以输出动态相位调整信号至主控模块；主控模块,还用于根据动态相位调整信号对动态力传感信号进行调整,基于调整后的动态力传感信号采样值,计算并输出待测压电样品的压电常数。本发明能够避免信号干扰,有效提高压电测量精度。(The invention relates to a piezoelectric measuring device, which comprises a main control module, a signal input module, a driving waveform generation module and a phase-locked loop module, wherein the main control module is used for controlling the signal input module to generate a driving waveform; the signal input module is used for acquiring dynamic force sensing signals and transmitting the dynamic force sensing signals to the phase-locked loop module and the main control module; the driving waveform generating module is used for generating a driving waveform signal according to the oscillation driving instruction of the main control module and transmitting the driving waveform signal to the phase-locked loop module and the oscillation driving interface of the peripheral equipment; the phase-locked loop module is used for detecting the phase difference between the dynamic force sensing signal and the driving waveform signal in real time and locking the phase difference so as to output a dynamic phase adjustment signal to the main control module; and the main control module is also used for adjusting the dynamic force sensing signal according to the dynamic phase adjusting signal, and calculating and outputting the piezoelectric constant of the piezoelectric sample to be detected based on the adjusted dynamic force sensing signal sampling value. The invention can avoid signal interference and effectively improve the piezoelectric measurement precision.)

1. A piezoelectric measuring device, comprising: the device comprises a main control module, a signal input module, a driving waveform generation module and a phase-locked loop module; the main control module is electrically connected with the driving waveform generation module, the signal input module is electrically connected with the phase-locked loop module, the phase-locked loop module is electrically connected with the main control module,

the signal input module is used for acquiring dynamic force sensing signals and transmitting the dynamic force sensing signals to the phase-locked loop module and the main control module;

the driving waveform generating module is used for generating a driving waveform signal according to the oscillation driving instruction of the main control module and transmitting the driving waveform signal to the phase-locked loop module and the oscillation driving interface of the peripheral equipment;

the phase-locked loop module is used for detecting the phase difference between the dynamic force sensing signal and the driving waveform signal in real time and locking the phase difference so as to output a dynamic phase adjustment signal to the main control module;

the main control module is used for outputting a driving instruction to the driving waveform generation module, adjusting the dynamic force sensing signal according to the dynamic phase adjustment signal, and calculating and outputting the piezoelectric constant of the piezoelectric sample to be detected based on the adjusted dynamic force sensing signal sampling value.

2. The piezoelectric measuring device according to claim 1, wherein the signal input module is further configured to collect a static force sensing signal and transmit the static force sensing signal to the phase-locked loop module and the main control module;

the phase-locked loop module is also used for detecting the phase difference between the static force sensing signal and the driving waveform signal in real time and locking the phase difference so as to output a static phase adjusting signal to the main control module;

the main control module is further used for adjusting the static force sensing signal according to the static phase adjusting signal, determining whether the piezoelectric sample to be tested is clamped or not based on the adjusted static force sensing signal sampling value and the preset static clamping force, and outputting a static force adjusting instruction to an external stepping driving interface.

3. The piezoelectric measuring device according to claim 1, wherein the phase-locked loop module includes a dynamic phase-locked loop circuit electrically connected to the driving waveform generating module and the signal input module, respectively;

the dynamic phase-locked loop circuit comprises a dynamic loop chip U21, a resistor R131, a resistor R134 and a capacitor C115;

the port SIGIN of the dynamic loop chip U21 is connected with the output end of the waveform generating circuit through the C115, the port VCONIN is connected with the output end of the signal input module through the resistor R131, and the port DEMOUT outputs a phase adjusting signal of a dynamic force sensing signal through the resistor R134.

4. The piezoelectric measuring device according to claim 3, wherein the phase-locked loop module further comprises a static phase-locked loop circuit electrically connected to the driving waveform generating module and the signal input module, respectively;

the static phase-locked loop circuit comprises a static loop chip U20, a resistor R122, a resistor R125 and a capacitor C111;

the port SIGIN of the static loop chip U20 is connected with the output end of the waveform generating circuit through a capacitor C111, the port VCOIN is connected with the output end of the signal input module through the resistor R122, and the port DEMOUT outputs a phase adjusting signal of a static force sensing signal through a resistor R125.

5. The piezoelectric measuring device according to claim 1, wherein the drive waveform signal includes a sine wave signal or a cosine wave signal.

6. The piezoelectric measuring device according to claim 2, wherein the main control module comprises a main control board and a micro control unit, the micro control unit is electrically connected with the main control board, and the micro control unit is further electrically connected with the signal input module, the phase-locked loop module and the driving waveform generation module respectively;

the main control board is used for outputting an oscillation driving instruction to the micro-control unit;

the micro-control unit is used for transmitting a driving instruction to the driving waveform generation module; the micro-control unit is also used for acquiring dynamic and static force sensing signals and corresponding phase adjustment signals transmitted by the signal input module and transmitting the signals to the main control board;

the main control board is further used for calculating and outputting the piezoelectric constant of the piezoelectric sample to be detected according to the dynamic force sensing signal and the corresponding phase adjusting signal, and determining whether the piezoelectric sample to be detected is clamped or not according to the static force sensing signal and the corresponding phase adjusting signal.

7. The piezoelectric measuring device according to claim 6, wherein the driving waveform generating module includes a waveform generating circuit and a waveform control circuit; the waveform generating circuit is electrically connected with the waveform control circuit; the waveform generating circuit is also electrically connected with the micro-control unit; the output end of the waveform generating circuit is electrically connected with the phase-locked loop module; the waveform control circuit is also electrically connected with the micro-control unit, and the output end of the waveform control circuit is connected with an external oscillation driving interface;

the waveform generating circuit is used for generating a corresponding waveform according to an enabling instruction of the micro-control unit, amplifying and outputting a driving waveform signal, and transmitting the driving waveform signal to the waveform control circuit; the waveform generating circuit is also used for transmitting a driving waveform signal to the phase-locked loop module;

and the waveform control circuit is used for adjusting the size of the driving waveform according to the waveform adjusting instruction of the micro-control unit and outputting the adjusted driving waveform signal to an external oscillation driving interface.

8. The piezoelectric measuring device according to claim 7, wherein the waveform generating circuit comprises a waveform generator U14, a capacitor C98, a resistor R97, a resistor R98, a resistor R99 and an operational amplifier chip U15B;

an enabling command input end of the waveform generator U14 is connected with the micro control unit, and a voltage output end is connected to a non-inverting input end of an operational amplifier chip U15B through a capacitor C98 and a resistor R97; the inverting input end of the operational amplifier chip U15B is grounded through a resistor R98 and connected to the output end of the operational amplifier chip U15B through a resistor R99, and the output end of the operational amplifier chip U15B is connected with the phase-locked loop module and the waveform control circuit.

9. The piezoelectric measuring device according to claim 8, wherein the waveform control circuit comprises a digital point pointer U16, a resistor R102, a resistor R103, a resistor R104, a resistor R119, a capacitor C101, and an operational amplifier chip U17A;

the VH end of the digital point location device U16 is connected to the output end of the operational amplifier chip U15B through a resistor R119, the Vw end of the digital point location device U16 is connected to the non-inverting input end of the operational amplifier chip U17A through a resistor R102, and the/INC end and the U/LD end of the digital point location device U16 are both connected with the micro-control unit; one end of the resistor R103 and the resistor R104 which are connected in series is connected to the output end of the operational amplifier chip U17A, and the other end of the resistor R103 and the resistor R104 are connected to a power supply; the inverting input end of the operational amplifier chip U17A is connected to a series connection point between the resistor R103 and the resistor R104; the output end of the operational amplifier chip U17A is connected with a capacitor C101 to output a driving waveform signal.

10. The piezoelectric measuring device according to claim 4, wherein the signal input module comprises a dynamic sensing circuit, a static sensing circuit, a digital-to-analog conversion circuit;

the dynamic sensing circuit is used for acquiring dynamic force sensing signals, amplifying the dynamic force sensing signals and transmitting the amplified dynamic force sensing signals to the analog-to-digital conversion circuit and the dynamic phase-locked loop circuit respectively;

the static sensing circuit is used for acquiring a static force sensing signal, and transmitting the static force sensing signal to the analog-to-digital conversion circuit and the static phase-locked loop circuit after amplification;

and the analog-to-digital conversion circuit is used for converting the dynamic force sensing signal and the static force sensing signal into corresponding digital signals and transmitting the digital signals to the micro control unit.

Technical Field

The application relates to the technical field of piezoelectric measurement, in particular to a piezoelectric measuring device based on a phase-locked loop technology.

Background

With the development of advanced intelligent manufacturing technology, the research and development of high-performance electronic materials and key functional devices are increasingly important, wherein the piezoelectric material is an important functional material for realizing the conversion and coupling of mechanical energy and electrical energy, and has wide application in the fields of aerospace, energy sources, advanced manufacturing, medical systems, weaponry and the like. However, in the process of research and development and application, the performance test of the piezoelectric material is very important.

According to the piezoelectric effect, when pressure is applied to a piezoelectric material, a potential difference is generated, which is called as a positive piezoelectric effect; on the contrary, when a voltage is applied, a mechanical stress is generated, which is called inverse piezoelectric effect. The piezoelectric constant is a conversion coefficient of a piezoelectric body for converting mechanical energy into electric energy or converting electric energy into mechanical energy, and reflects the coupling relation between the elastic (mechanical) property and the dielectric property of the piezoelectric material. The piezoelectric constants can be classified into three types, namely longitudinal piezoelectric constants (e.g., d33, d11, d22), transverse piezoelectric constants (e.g., d31, d32), and tangential piezoelectric constants (e.g., d15, d24, d 36).

The existing piezoelectric measuring instrument based on the quasi-static method generally adopts static force and dynamic force which can be respectively and independently driven, the static force is provided by a main control panel driving stepping motor, the dynamic force is generated by an oscillator, so that the dynamic force and the static force can simultaneously realize full-range loading, in the piezoelectric testing process, the testing precision is influenced by various factors such as signal interference, especially for a sample with weak piezoelectric effect, the acquired piezoelectric signal is weak, and the testing precision is often low due to noise interference, therefore, the problem that the testing precision is low due to the signal interference of the existing piezoelectric measuring equipment is considered by the inventor to be further solved.

Disclosure of Invention

In view of this, the present application provides a piezoelectric measuring device, which is used to solve the technical problem of low test accuracy caused by signal interference.

In order to solve the above problem, the present invention provides a piezoelectric measuring device including: the device comprises a main control module, a signal input module, a driving waveform generation module and a phase-locked loop module; the main control module is electrically connected with the driving waveform generation module, the signal input module is electrically connected with the phase-locked loop module, the phase-locked loop module is electrically connected with the main control module,

the signal input module is used for acquiring dynamic force sensing signals and transmitting the dynamic force sensing signals to the phase-locked loop module and the main control module;

the driving waveform generating module is used for generating a driving waveform signal according to the oscillation driving instruction of the main control module and transmitting the driving waveform signal to the phase-locked loop module and the oscillation driving interface of the peripheral equipment;

the phase-locked loop module is used for detecting the phase difference between the dynamic force sensing signal and the driving waveform signal in real time and locking the phase difference so as to output a dynamic phase adjustment signal to the main control module;

the main control module is used for outputting a driving instruction to the driving waveform generation module, adjusting the dynamic force sensing signal according to the dynamic phase adjustment signal, and calculating and outputting the piezoelectric constant of the piezoelectric sample to be detected based on the adjusted dynamic force sensing signal sampling value.

Optionally, the signal input module is further configured to collect a static force sensing signal and transmit the static force sensing signal to the phase-locked loop module and the main control module;

the phase-locked loop module is also used for detecting the phase difference between the static force sensing signal and the driving waveform signal in real time and locking the phase difference so as to output a static phase adjusting signal to the main control module;

the main control module is further used for adjusting the static force sensing signal according to the static phase adjusting signal, determining whether the piezoelectric sample to be tested is clamped or not based on the adjusted static force sensing signal sampling value and the preset static clamping force, and outputting a static force adjusting instruction to an external stepping driving interface.

Optionally, the phase-locked loop module includes a dynamic phase-locked loop circuit, and the dynamic phase-locked loop circuit is electrically connected to the driving waveform generating module and the signal input module respectively;

the dynamic phase-locked loop circuit comprises a dynamic loop chip U21, a resistor R131, a resistor R134 and a capacitor C115;

the port SIGIN of the dynamic loop chip U21 is connected with the output end of the waveform generating circuit through the C115, the port VCONIN is connected with the output end of the signal input module through the resistor R131, and the port DEMOUT outputs a phase adjusting signal of a dynamic force sensing signal through the resistor R134.

Optionally, the phase-locked loop module further includes a static phase-locked loop circuit, and the static phase-locked loop circuit is electrically connected to the driving waveform generating module and the signal input module respectively;

the static phase-locked loop circuit comprises a static loop chip U20, a resistor R122, a resistor R125 and a capacitor C111;

the port SIGIN of the static loop chip U20 is connected with the output end of the waveform generating circuit through a capacitor C111, the port VCOIN is connected with the output end of the signal input module through the resistor R122, and the port DEMOUT outputs a phase adjusting signal of a static force sensing signal through a resistor R125.

Optionally, the driving waveform signal includes a sine wave signal or a cosine wave signal.

Optionally, the main control module includes a main control board and a micro control unit, the micro control unit is electrically connected to the main control board, and the micro control unit is further electrically connected to the signal input module, the phase-locked loop module, and the driving waveform generation module, respectively;

the main control board is used for outputting an oscillation driving instruction to the micro-control unit;

the micro-control unit is used for transmitting a driving instruction to the driving waveform generation module; the micro-control unit is also used for acquiring dynamic and static force sensing signals and corresponding phase adjustment signals transmitted by the signal input module and transmitting the signals to the main control board;

the main control board is further used for calculating and outputting the piezoelectric constant of the piezoelectric sample to be detected according to the dynamic force sensing signal and the corresponding phase adjusting signal, and determining whether the piezoelectric sample to be detected is clamped or not according to the static force sensing signal and the corresponding phase adjusting signal.

Optionally, the driving waveform generating module includes a waveform generating circuit and a waveform control circuit; the waveform generating circuit is electrically connected with the waveform control circuit; the waveform generating circuit is also electrically connected with the micro-control unit; the output end of the waveform generating circuit is electrically connected with the phase-locked loop module; the waveform control circuit is also electrically connected with the micro-control unit, and the output end of the waveform control circuit is connected with an external oscillation driving interface;

the waveform generating circuit is used for generating a corresponding waveform according to an enabling instruction of the micro-control unit, amplifying and outputting a driving waveform signal, and transmitting the driving waveform signal to the waveform control circuit; the waveform generating circuit is also used for transmitting a driving waveform signal to the phase-locked loop module;

and the waveform control circuit is used for adjusting the size of the driving waveform according to the waveform adjusting instruction of the micro-control unit and outputting the adjusted driving waveform signal to an external oscillation driving interface.

Optionally, the waveform generating circuit includes a waveform generator U14, a capacitor C98, a resistor R97, a resistor R98, a resistor R99, and an operational amplifier chip U15B;

an enabling command input end of the waveform generator U14 is connected with the micro control unit, and a voltage output end is connected to a non-inverting input end of an operational amplifier chip U15B through a capacitor C98 and a resistor R97; the inverting input end of the operational amplifier chip U15B is grounded through a resistor R98 and connected to the output end of the operational amplifier chip U15B through a resistor R99, and the output end of the operational amplifier chip U15B is connected with the phase-locked loop module and the waveform control circuit.

Optionally, the waveform control circuit includes a digital point location device U16, a resistor R102, a resistor R103, a resistor R104, a resistor R119, a capacitor C101, and an operational amplifier chip U17A;

the VH end of the digital point location device U16 is connected to the output end of the operational amplifier chip U15B through a resistor R119, the Vw end of the digital point location device U16 is connected to the non-inverting input end of the operational amplifier chip U17A through a resistor R102, and the/INC end and the U/LD end of the digital point location device U16 are both connected with the micro-control unit; one end of the resistor R103 and the resistor R104 which are connected in series is connected to the output end of the operational amplifier chip U17A, and the other end of the resistor R103 and the resistor R104 are connected to a power supply; the inverting input end of the operational amplifier chip U17A is connected to a series connection point between the resistor R103 and the resistor R104; the output end of the operational amplifier chip U17A is connected with a capacitor C101 to output a driving waveform signal.

Optionally, the signal input module includes a dynamic sensing circuit, a static sensing circuit, and a digital-to-analog conversion circuit;

the dynamic sensing circuit is used for acquiring dynamic force sensing signals, amplifying the dynamic force sensing signals and transmitting the amplified dynamic force sensing signals to the analog-to-digital conversion circuit and the dynamic phase-locked loop circuit respectively;

the static sensing circuit is used for acquiring a static force sensing signal, and transmitting the static force sensing signal to the analog-to-digital conversion circuit and the static phase-locked loop circuit after amplification;

and the analog-to-digital conversion circuit is used for converting the dynamic force sensing signal and the static force sensing signal into corresponding digital signals and transmitting the digital signals to the micro control unit.

The application has the following beneficial technical effects: collecting dynamic force sensing signals through a signal input module, transmitting the dynamic force sensing signals to a phase-locked loop module as feedback signals, and transmitting the feedback signals to a micro-control unit; outputting a driving waveform through a driving waveform generating module, transmitting the driving waveform to an external oscillation driving interface, and transmitting the driving waveform to a phase-locked loop module; the phase-locked loop module is used for carrying out phase locking on the dynamic force sensing signal and the driving waveform and transmitting a phase difference signal of the dynamic force sensing signal and the driving waveform signal which are detected in real time to the main control module; the main control module adjusts the phase of the dynamic force sensing signal according to the dynamic phase adjusting signal so as to accurately obtain the frequency sampling values of the dynamic force sensing signal and the static force sensing signal, thereby effectively avoiding the situations of signal interference and signal inundation. And calculating and outputting the piezoelectric constant of the piezoelectric sample to be measured according to the adjusted frequency sampling value of the dynamic force sensing signal, thereby improving the piezoelectric measurement precision.

Drawings

FIG. 1 is a schematic block diagram of one embodiment of a piezoelectric measuring device provided by the present invention;

FIG. 2 is a circuit diagram of one embodiment of a waveform generation circuit provided by the present invention;

FIG. 3 is a circuit diagram of one embodiment of an output waveform control circuit provided by the present invention;

FIG. 4 is a circuit diagram of one embodiment of a dynamic phase locked loop circuit provided by the present invention;

FIG. 5 is a circuit diagram of one embodiment of a static phase-locked loop circuit provided by the present invention;

FIG. 6 is a functional block diagram of one embodiment of a main control board provided by the present invention;

FIG. 7(a) is a circuit diagram of an embodiment of a first pressure detecting unit provided in the present invention;

FIG. 7(b) is a circuit diagram of an embodiment of a first pressure detecting unit provided in the present invention;

FIG. 8 is a circuit diagram of one embodiment of a drive unit provided by the present invention;

FIG. 9 is a circuit diagram of one embodiment of a signal acquisition board provided by the present invention;

FIG. 10 is a circuit diagram of one embodiment of a static sensing circuit provided by the present invention;

FIG. 11 is a circuit diagram of one embodiment of a dynamic sensing circuit provided by the present invention;

description of reference numerals: 1. a main control module; 2. a signal input module; 3. a drive waveform generation module; 4. a phase-locked loop module;

Detailed Description

The present application is described in further detail below with reference to figures 1-11.

The embodiment of the application discloses piezoelectric measurement device, refer to fig. 1, the device includes: the device comprises a main control module 1, a signal input module 2, a driving waveform generation module 3 and a phase-locked loop module 4; the main control module 1 is electrically connected with the driving waveform generation module 3, the signal input module 2 is electrically connected with the phase-locked loop module 4, and the phase-locked loop module 4 is electrically connected with the main control module 1.

The signal input module 2 is used for acquiring dynamic force sensing signals and transmitting the dynamic force sensing signals to the phase-locked loop module 4 and the main control module 1; the driving waveform generating module 3 is used for generating a driving waveform signal according to the driving instruction of the main control module 1 and transmitting the driving waveform signal to the phase-locked loop module 4 and an oscillation driving interface of the peripheral equipment; the phase-locked loop module 4 is used for detecting the phase difference between the dynamic force sensing signal and the driving waveform signal in real time and locking the phase difference so as to output a dynamic phase adjustment signal to the main control module 1; the main control module 1 is configured to output a driving instruction to the driving waveform generation module, and is further configured to adjust the dynamic force sensing signal according to the dynamic phase adjustment signal, and calculate and output a piezoelectric constant of the piezoelectric sample to be measured based on the adjusted dynamic force sensing signal sampling value.

Optionally, the signal input module is further configured to collect a static force sensing signal and transmit the static force sensing signal to the phase-locked loop module and the main control module; the phase-locked loop module is also used for detecting the phase difference between the static force sensing signal and the driving waveform signal in real time and locking the phase difference so as to output a static phase adjusting signal to the main control module; the main control module is further used for adjusting the static force sensing signal according to the static phase adjusting signal, determining whether the piezoelectric sample to be tested is clamped or not based on the adjusted static force sensing signal sampling value and the preset static clamping force, and outputting a static force adjusting instruction to the external stepping drive interface.

Optionally, the main control module includes a main control board and a micro control unit, the micro control unit is electrically connected to the main control board, and the micro control unit is further electrically connected to the signal input module, the phase-locked loop module, and the driving waveform generation module, respectively.

The main control board is used for outputting an oscillation driving instruction to the micro-control unit; the micro-control unit is used for transmitting the driving instruction to the driving waveform generation module; the micro-control unit is also used for acquiring dynamic and static force sensing signals and corresponding phase adjustment signals transmitted by the signal input module and transmitting the signals to the main control board; the main control board is further used for calculating and outputting the piezoelectric constant of the piezoelectric sample to be detected according to the dynamic force sensing signal and the corresponding phase adjusting signal, and determining whether the piezoelectric sample to be detected is clamped or not according to the static force sensing signal and the corresponding phase adjusting signal.

Optionally, the signal input module includes a dynamic sensing circuit, a static sensing circuit, and a digital-to-analog conversion circuit; the dynamic sensing circuit is used for acquiring dynamic force sensing signals, amplifying the dynamic force sensing signals and transmitting the amplified dynamic force sensing signals to the analog-to-digital conversion circuit and the dynamic phase-locked loop circuit respectively; the static sensing circuit is used for acquiring a static force sensing signal, and transmitting the static force sensing signal to the analog-to-digital conversion circuit and the static phase-locked loop circuit after amplification; and the analog-to-digital conversion circuit is used for converting the dynamic force sensing signal and the static force sensing signal into corresponding digital signals and transmitting the digital signals to the micro control unit.

The piezoelectric measuring device of the embodiment further comprises a stepping motor and a pressure sensor which are electrically connected with the main control board, a dynamic deformation sensor (dynamic sensor) and a static deformation sensor (static sensor) which are electrically connected with the signal input module, and a modal shaker which is electrically connected with the driving waveform generating module, so that the piezoelectric constant measurement of the piezoelectric sample to be measured is completed in a cooperation manner.

In the measurement process, a driving waveform signal output by the driving waveform generation module is transmitted to the modal shaker, so that after the modal shaker oscillates, the dynamic deformation sensor detects a dynamic force sensing signal of the piezoelectric sample to be measured, and the dynamic sensing circuit acquires the dynamic force sensing signal detected by the dynamic deformation sensor; the main control board drives the stepping motor to enable the measuring clamp to clamp the piezoelectric sample to be measured, the static deformation sensor detects a static force sensing signal, and the static sensing circuit collects the static force sensing signal detected by the static deformation sensor. In addition, the real-time driving force generated by the stepping motor is detected by the pressure sensor and transmitted to the main control board. The dynamic sensing circuit and the static sensing circuit transmit dynamic force sensing signals and static force sensing signals to the micro-control unit through the digital-to-analog conversion circuit, and the dynamic force sensing signals and the static force sensing signals are transmitted to the main control board through the micro-control unit.

In addition, the dynamic sensing circuit and the static sensing circuit transmit the dynamic force sensing signal and the static force sensing signal to the phase-locked loop module as feedback signals, detect the real-time phase difference between the dynamic force sensing signal and the driving waveform signal through the phase locking function of the phase-locked loop module, output corresponding phase adjustment signals to the micro-control unit, detect the real-time phase difference between the static force sensing signal and the driving waveform signal, and output corresponding phase adjustment signals to the micro-control unit; the micro-control unit adjusts the phases of the dynamic force sensing signal and the static force sensing signal according to the dynamic phase adjusting signal and the static phase adjusting signal so as to accurately obtain the frequency sampling values of the dynamic force sensing signal and the static force sensing signal, thereby effectively avoiding the situations of signal interference and signal submergence; the micro-control unit transmits the adjusted dynamic force sensing signal, the adjusted static force sensing signal and the corresponding phase adjustment signal to the main control board, and the algorithm of the main control board calculates and outputs the piezoelectric constant of the piezoelectric sample to be measured according to the sampling value of the adjusted dynamic force sensing signal; and determining whether the piezoelectric sample to be tested is clamped or not according to the adjusted sampling value of the static force sensing signal and a preset static clamping force so as to output a static force adjusting instruction to an external stepping driving interface.

In one embodiment, the longitudinal piezoelectric constant d of the piezoelectric sample to be measured is measured₃₃The calculation formula is specifically as follows:wherein F is the corrected dynamic force, C is the known capacitance value, and V is the known voltage value. This embodiment can measure d15 (lateral piezoelectric constant) and d31 (tangential piezoelectric constant) by replacing the measuring jig. In one embodiment, the static clamping force of the piezoelectric sample to be tested is set to 10N.

Optionally, the driving waveform generating module includes a waveform generating circuit and a waveform control circuit; the waveform generating circuit is electrically connected with the waveform control circuit; the waveform generating circuit is also electrically connected with the micro-control unit; the output end of the waveform generating circuit is electrically connected with the phase-locked loop module; the waveform control circuit is also electrically connected with the micro-control unit, and the output end of the waveform control circuit is connected with an external oscillation driving interface;

the waveform generating circuit is used for generating a corresponding waveform according to the enabling instruction of the micro-control unit, amplifying and outputting a driving waveform signal and transmitting the driving waveform signal to the waveform control circuit; the waveform generating circuit is also used for transmitting the driving waveform signal to the phase-locked loop module;

and the waveform control circuit is used for adjusting the size of the driving waveform according to the waveform adjusting instruction of the micro-control unit and outputting the adjusted driving waveform signal to an external oscillation driving interface.

Optionally, referring to fig. 2, the waveform generating circuit includes a waveform generator U14, a capacitor C98, a resistor R97, a resistor R98, a resistor R99, and an operational amplifier chip U15B; an enable command input end of the waveform generator U14 is connected with the micro control unit, and a voltage output end is connected to a non-inverting input end of the operational amplifier chip U15B through a capacitor C98 and a resistor R97; the inverting input end of the operational amplifier chip U15B is grounded through a resistor R98 and connected to the output end of the operational amplifier chip U15B through a resistor R99, and the output end of the operational amplifier chip U15B is connected with the phase-locked loop module and the waveform control circuit. In the present embodiment, the drive waveform signal includes a sine wave signal or a cosine wave signal.

Optionally, referring to fig. 3, the waveform control circuit includes a digital point location U16, a resistor R102, a resistor R103, a resistor R104, a resistor R119, a capacitor C101, and an operational amplifier chip U17A; the VH end of the digital point location device U16 is connected to the output end of the operational amplifier chip U15B through a resistor R119, the Vw end of the digital point location device U16 is connected to the non-inverting input end of the operational amplifier chip U17A through a resistor R102, and the/INC end and the U/LD end of the digital point location device U16 are both connected with a micro-control unit; one end of the resistor R103 and the resistor R104 which are connected in series is connected to the output end of the operational amplifier chip U17A, and the other end is connected to a power supply; the inverting input end of the operational amplifier chip U17A is connected to the series connection point between the resistor R103 and the resistor R104; the output end of the operational amplifier chip U17A is connected to output a driving waveform signal through a capacitor C101.

In one embodiment, waveform generator U14 is a programmable waveform generator, such as an AD9833 chip, capable of generating sine wave, triangle wave, and square wave outputs. The operational amplifier chip U15B is of a model number such as TL 082. The waveform generator U14 communicates with the micro control unit via the SPI. After the micro-control unit outputs a waveform enabling instruction, the waveform generator U14 outputs a corresponding sine waveform or cosine waveform, and a V-SIN1 signal is output after passing through an operational amplifier chip U15B; the V-SIN1 signal is output in two paths, one path is output to the output waveform control circuit, and the other path is output to the phase-locked loop module. In one embodiment, the digital point location U16 is a model such as an X9C104 chip. The micro-control unit is connected to the first interface/INC and the second interface U/LD of the X9C104 chip to adjust the potential of the input V-SIN1 signal, so that the size of the output driving waveform can be controlled; further, the output driving waveform is amplified by an operational amplifier chip U17A and then output to power the modal exciter. In the embodiment, the output sine waveform can be controlled to be 0-10V and 0-300 HZ, so as to realize the function of frequency conversion test.

Optionally, the phase-locked loop module includes a dynamic phase-locked loop circuit, and referring to fig. 4, the dynamic phase-locked loop circuit is electrically connected to the driving waveform generating module and the signal input module, respectively; the dynamic phase-locked loop circuit comprises a dynamic loop chip U21, a resistor R131, a resistor R134 and a capacitor C115; the port SIGIN of the dynamic loop chip U21 is connected to the output terminal of the waveform generation circuit through the C115, the port VCOIN is connected to the output terminal of the signal input module through the resistor R131, and the port DEMOUT outputs the phase adjustment signal of the dynamic force sensing signal through the resistor R134.

Optionally, the phase-locked loop module further includes a static phase-locked loop circuit, and referring to fig. 5, the static phase-locked loop circuit is electrically connected to the driving waveform generating module and the signal input module, respectively; the static phase-locked loop circuit comprises a static loop chip U20, a resistor R122, a resistor R125 and a capacitor C111;

the port SIGIN of the static loop chip U20 is connected to the output terminal of the waveform generation circuit through the capacitor C111, the port VCOIN is connected to the output terminal of the signal input module through the resistor R122, and the port DEMOUT outputs the phase adjustment signal of the static force sensing signal through the resistor R125.

In one embodiment, the static loop chip U20 and the dynamic loop chip U21 may be phase-locked loop chips of models such as SN74LV 4046A; it should be noted that the Phase-locked Loop chip includes three parts, namely, a Phase Detector (PD), a low-pass Filter (LF), and a Voltage Controlled Oscillator (VCO); the dynamic phase-locked loop circuit and the dynamic phase-locked loop circuit have the same working principle, and the dynamic phase-locked loop circuit is used for illustrating the phase difference between an input signal V-SIN1, namely a driving waveform signal, and an output signal Vx1, namely a dynamic force sensing signal, is detected, the phase difference signal detected in real time is converted into a voltage signal through a phase discriminator to be output to a micro-control unit, the voltage signal is output to a low-pass filter to be filtered to form a control voltage of a voltage-controlled oscillator, the frequency of the output signal of the voltage-controlled oscillator is controlled, and the frequency and the phase of the output signal of the voltage-controlled oscillator are fed back to the phase discriminator through a feedback path. When the frequency of the output signal reflects the frequency of the input signal in proportion, the output voltage and the input voltage keep a fixed phase difference value, so that the phases of the output voltage and the input voltage are locked, the driving waveform signal V-SIN1, the static force sensing signal Vx1 and the dynamic force sensing signal Vx2 are locked in phase, and in the locking process, the phase discriminator outputs a phase adjusting signal to the micro-control unit in real time and serves as a supplement signal of the dynamic sensing signal, so that the frequency and the phase of the measuring signal are kept synchronous with the frequency and the phase of the oscillation driving signal, and the interference of noise is avoided.

Optionally, the piezoelectric measuring device of this embodiment further includes a power module and a display module, the power module is connected to the main control module, the signal input module, the driving waveform generation module and the phase-locked loop module, respectively, and the display module is connected to the power module and the main control module, respectively.

The power supply module is used for supplying power to the main control module, the signal input module, the driving waveform generation module, the phase-locked loop module and the display module; and the display module is used for displaying the piezoelectric constant measurement result.

In one embodiment, two power supplies are used, namely a 24V DC power supply and a 220V AC power supply; the power supply module adopts a power supply chip, the type of which is HE12P24LRN, and converts an input 220V alternating current power supply into a 12V 2A direct current power supply; the 12V direct-current power supply is divided into three paths to supply power to the main control module, the signal acquisition module and the display module, in addition, 5V power is output by one path through a voltage reduction chip with the model of LM2576-5, and the three paths are divided to supply power to the main control module, the signal acquisition board and the display module. In a specific embodiment, the power module is provided with three light strips. And a 24V direct-current power supply supplies power to the stepping motor and the three lamp strips. In one embodiment, the display module may employ an LCD panel or an LED panel.

Optionally, the main control board includes a main control unit, a pressure detection unit and a driving unit; the pressure detection unit and the driving unit are respectively connected with the main control unit.

The main control unit is used for outputting a stepping driving instruction to the driving unit; the driving unit is used for driving the stepping motor so that the piezoelectric measuring device applies force to the piezoelectric sample to be measured; the pressure detection unit is used for acquiring a pressure signal generated when the stepping motor moves and detected by a pressure sensor of the piezoelectric measurement device; the main control unit is also used for acquiring a pressure signal of the pressure detection unit, a dynamic force sensing signal, a static force sensing signal and a corresponding phase adjustment signal of the signal input module, and calculating and outputting a piezoelectric constant of the piezoelectric sample to be detected according to the dynamic force sensing signal and the corresponding phase adjustment signal; and if the piezoelectric sample to be detected is not clamped, outputting a stepping adjustment signal according to the static phase adjustment signal and the pressure signal so as to adjust the driving force of the stepping motor.

Optionally, the main control board further includes a first voltage reduction unit, an input end of the first voltage reduction unit is connected to an output end of the power module, and an output end of the first voltage reduction unit is connected to the main control unit. The first voltage reduction unit is used for reducing the voltage of the direct-current power supply output by the power supply module and supplying power to the main control unit. In one embodiment, the first buck unit is an LDO chip, such as AMS1117-3.3, for outputting 3.3V after the 5V DC power supply is stepped down.

In a specific embodiment, referring to fig. 6, the main control unit adopts a single chip microcomputer MCU, and the model is as follows: STM32F 407V; two 485 communication interfaces, a network port, a 232 communication protocol interface and a USB interface are arranged outside the main control unit; and the stepping motor and the micro-control unit are respectively connected for communication connection through two 485 communication interfaces. The first voltage reduction unit adopts an LDO chip, such as AMS1117-3.3, and outputs 3.3V after reducing the voltage of a 5V direct current power supply.

In a specific embodiment, the pressure detection unit includes a first pressure detection circuit and a second pressure detection circuit; the input end of the first pressure detection circuit is connected with the pressure sensor, and the output end of the first pressure detection circuit is connected with the main control unit; the input end of the second pressure detection circuit is connected with the pressure sensor, and the output end of the second pressure detection circuit is connected with the main control unit;

referring to fig. 7(a), the first pressure detection single circuit includes an operational amplifier chip U4B, a resistor R7, a resistor R8, a resistor R9, a resistor R10, and a port CN 15. The non-inverting input end of the operational amplifier chip U4B is connected to a first interface of a port CN15 through a resistor R8, and the port CN15 is used as a first signal input end; the second interface of the port CN15 is connected to the output end of the operational amplifier chip U4B through a resistor R7 and a resistor R9; the inverting input end of the operational amplifier chip U4B is connected to the series connection point of the resistor R7 and the resistor R9; the output end of the operational amplifier chip U4B outputs a pressure detection signal to the main control unit through a resistor R10.

Referring to fig. 7(b), the second pressure detection single circuit includes an operational amplifier chip U4A, a resistor R11, a resistor R12, a resistor R13, a resistor R14, and a port CN 16. The non-inverting input end of the operational amplifier chip U4A is connected to the first interface of the port CN16 through a resistor R12, and the port CN16 is used as a second signal input end; the second interface of the port CN16 is connected to the output end of the operational amplifier chip U4A through a resistor R11 and a resistor R13; the inverting input end of the operational amplifier chip U4A is connected to the series connection point of the resistor R11 and the resistor R13; the output end of the operational amplifier chip U4A outputs a pressure detection signal to the main control unit through a resistor R14.

In a specific embodiment, the operational amplifier chip U4A and the operational amplifier chip U4B are operational amplifier chips of models such as TL 082; signals of the pressure sensor are input to the corresponding pressure detection circuits through the port CN15 and the port CN16, amplified by the amplification circuit formed by the TL082 operational amplifier chip, and then transmitted to the I/O interface corresponding to the main control unit, it should be noted that the I/O interface of the main control unit has an ADC function.

In a specific embodiment, referring to fig. 8, the driving unit adopts a driving chip U10, and the driving chip U10 is connected to the main control unit; the driving chip is used for converting the stepping driving instruction output by the main control unit into a driving signal to be output to the stepping motor.

In one embodiment, the driver IC U10 is a type DS26LV31 TM/NOPB; after the main control unit outputs a drive control instruction, the drive control instruction is converted into a drive signal by the drive chip U10 and is output to the stepper motor socket CN 23.

In a specific embodiment, the micro control unit, the signal input module, the driving waveform generating module and the phase-locked loop module are integrated on a signal collecting board, referring to fig. 9, the collecting board further includes a second voltage-reducing unit, an input end of the second voltage-reducing unit is connected to an output end of the power module, and an output end of the second voltage-reducing unit is connected to the micro control unit. The first voltage reduction unit is used for reducing the voltage of the direct-current power supply output by the power supply module and supplying power to the micro-control unit. In one embodiment, the second buck unit is an LDO chip, such as AMS1117-3.3, for outputting 3.3V after the 5V DC power supply is stepped down.

In one embodiment, referring to fig. 10, the static sensing circuit of the signal input module includes an operational amplifier chip U18, a resistor R109, a resistor R110, a resistor R111, a resistor R112, a resistor R113, a capacitor C104, a capacitor C105, a capacitor C106, and a port CN 29. The reverse input end of the operational amplifier chip U18 is connected to the second interface of the port CN29 sequentially through the resistor R111, the capacitor C104 and the resistor R110, the first interface of the port CN29 is grounded through the resistor R109, and the port CN29 is used as a static force sensing signal input end; the capacitor C105 is connected in parallel with two ends of the resistor R111; the equidirectional input end of the operational amplifier chip U18 is grounded through a resistor R112; one end of the capacitor C106 is connected to the output end of the operational amplifier chip U18, and the other end is connected to a series connection point between the resistor R110 and the capacitor C104; the resistor R113 is connected in parallel across the capacitor C106.

Referring to fig. 11, the dynamic sensing circuit of the signal input module includes an operational amplifier chip U19, a resistor R114, a resistor R115, a resistor R116, a resistor R117, a resistor R118, a capacitor C108, a capacitor C109, a capacitor C110, and a port CN 30. The inverting input end of the operational amplifier chip U19 is connected to the second interface of the port CN30 sequentially through the resistor R116, the capacitor C108 and the resistor R115, the first interface of the port CN30 is grounded through the resistor R114, and the port CN30 is used as a dynamic force sensing signal input end; the capacitor C109 is connected in parallel to two ends of the resistor R116; the non-inverting input end of the operational amplifier chip U19 is grounded through a resistor R117; one end of the capacitor C110 is connected with the output end of the operational amplifier chip U19, the other end of the capacitor C110 is connected to the series connection point between the resistor R115 and the capacitor C108, and the resistor R118 is connected to the two ends of the capacitor C110 in parallel.

In a specific embodiment, the operational amplifier chip U18 and the operational amplifier chip U19 are OP 117; referring to fig. 6, data measured by the static deformation sensor is input from a port CN29 of the static sensing circuit, is amplified in proportion by an operational amplifier chip U18, and then outputs a signal Vx 1; referring to fig. 7, data measured by the dynamic deformation sensor is input from a port CN30 of the dynamic sensing circuit, is amplified in proportion by an operational amplifier chip U19, and then outputs a signal Vx 2. It should be noted that, the dynamic and static sensing circuits are all module finished products, and automatically convert the detected force values into voltage signals in proportion for output.

In a specific embodiment, the analog-to-digital conversion circuit adopts an analog-to-digital conversion chip with a model number of ADS 1256; in the embodiment, the analog-to-digital conversion chip can adopt two signal acquisition modes, wherein one mode is to acquire signals independently, namely to acquire a signal Vx1 and a signal Vx2 respectively, the other mode is to acquire a signal Vx1 and a signal Vx as differential signals, and the two signal acquisition modes are selected from one mode; furthermore, the analog-to-digital conversion chip converts the acquired signals into corresponding digital signals and transmits the digital signals to the micro-control unit. In this embodiment, the analog-to-digital conversion chip communicates with the micro control unit in an SPI communication manner.

The frequency test range of the piezoelectric measuring device of the embodiment is as follows: 0-300 HZ, minimum resolution: 0.1Hz, a calibration frequency of 110Hz (typical); the dynamic force test range is: 0.05-0.5N, static test force: 10N, minimum resolution ± 0.01N, calibration force 0.25N (typical value); the measurement range includes:

10PC/N，Accuracy：±2％±0.01PC/N，Loading：0.1μF；

100PC/N，Accuracy：±2％±0.1pC/N，Loading：1.0μF；

1000PC/N，Accuracy：±2％±1pC/N，Loading：1.0μF；

10000PC/N，Accuracy：±2％±1pC/N，Loading：1.0μF。

the piezoelectric measuring device of the embodiment collects dynamic force sensing signals through the signal input module, transmits the dynamic force sensing signals to the phase-locked loop module as feedback signals, and simultaneously transmits the feedback signals to the micro-control unit; the phase-locked loop module locks the phase of the dynamic force sensing signal and the driving waveform, and transmits the phase difference signal of the dynamic force sensing signal and the driving waveform signal detected in real time to the micro-control unit, so that the micro-control unit adjusts the phase of the dynamic force sensing signal according to the dynamic phase adjusting signal to accurately obtain the frequency sampling value of the dynamic force sensing signal and the static force sensing signal, thereby effectively avoiding signal interference and submergence. The micro-control unit transmits the adjusted dynamic force sensing signal and the corresponding phase adjustment signal to the main control board, and the piezoelectric constant of the piezoelectric sample to be measured is calculated and output by the algorithm of the main control board, so that the piezoelectric measurement precision is improved.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules, so as to perform all or part of the functions described above. The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.