CN114637195A - Binary coded digital self-induction piezoelectric stack device and working method - Google Patents

Binary coded digital self-induction piezoelectric stack device and working method Download PDF

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Publication number
CN114637195A
CN114637195A CN202210167766.3A CN202210167766A CN114637195A CN 114637195 A CN114637195 A CN 114637195A CN 202210167766 A CN202210167766 A CN 202210167766A CN 114637195 A CN114637195 A CN 114637195A
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digital
self
signal
compensation
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凌杰
陈龙
朱玉川
张洺铭
段榆洲
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/0205—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric not using a model or a simulator of the controlled system
    • G05B13/024—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric not using a model or a simulator of the controlled system in which a parameter or coefficient is automatically adjusted to optimise the performance

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Abstract

The invention discloses a binary coded digital self-induction piezoelectric stack device and a working method thereof, wherein the binary coded digital self-induction piezoelectric stack device comprises the following steps: the device comprises a self-induction unit, a compensation unit, a digital driving unit and a digital control unit; the digital driving unit comprises a plurality of pieces of third piezoelectric materials which are axially overlapped, the compensation unit comprises a single piece of second piezoelectric material, and the self-induction unit comprises a single piece of first piezoelectric material; the digital driving unit, the compensation unit and the self-induction unit are sequentially installed; the compensation unit is used for performing precision compensation on the displacement output by the digital driving unit; the self-induction unit is used for sensing the output displacement of the digital driving unit; the digital control unit generates a digital control signal and a precision compensation signal; the digital control unit outputs a digital driving signal to drive the digital driving unit to output displacement and transmits a precision compensation signal to the compensation unit. The invention can realize continuous stepped regulation of the output displacement of the stacked piezoelectric material through the digital driving signal, realize the closed-loop control and precision compensation of the piezoelectric stack and eliminate the hysteresis.

Description

Binary coded digital self-induction piezoelectric stack device and working method
Technical Field
The invention relates to the technical field of intelligent material actuators, in particular to a binary coded digital self-induction piezoelectric stack device and a working method.
Background
The electromechanical converter is one of the key elements of an electro-hydraulic servo valve and even a hydraulic control system as a bridge for connecting the electric element and the hydraulic mechanical element of the electromechanical converter. The performance of the electromechanical converter is good and bad, and is directly related to the performance index of the electro-hydraulic control system. The stacked piezoelectric material is a motor conversion intelligent material capable of outputting linear displacement under the action of an electric field. Compared with other forms of intelligent materials such as magnetostrictive materials and shape memory alloys, the stacked piezoelectric material has the advantages of small volume, fast response, large output force, simple driving mode and the like, and is widely applied to various electromechanical systems.
However, in terms of a driving method, all the existing stack-type piezoelectric materials adopt a series structure, piezoelectric sheets with equal thicknesses are axially overlapped, and an excitation voltage is applied and simultaneously driven. Meanwhile, the driving has the defects of poor reliability, and if a certain layer of piezoelectric material in the stack breaks down in working, the whole piezoelectric stack fails and generates heat seriously in working.
As for the driving signal, the existing stack type piezoelectric materials all use an analog signal. The analog driving signal has the disadvantages of serious hysteresis nonlinearity and poor anti-interference capability, and a complex control strategy needs to be designed to overcome the electromagnetic interference of a working environment. In the serial structure form, the maximum output displacement of the stacked piezoelectric material is adjusted by increasing the number of the piezoelectric sheets which are radially stacked. Under the driving mode of analog signals, the output displacement amplitude of the stacked piezoelectric material is controlled by adjusting the voltage amplitude of the driving signals.
Because inherent hysteresis nonlinearity exists between the driving signal and the output displacement of the piezoelectric material, domestic and foreign scholars successively put forward various feedforward control strategies in order to obtain linear output displacement.
Document 1: the method comprises the steps of Fangchu, Guokui, Xuxin, Jiangshuang, Wang Tan Jiang Feng, piezoelectric ceramic hysteresis nonlinear feedforward compensator [ J ], optical precision engineering, 2016,24(09): 2217-.
Document 2: the experimental result shows that after compensation is carried out by using the built hysteresis inverse model, the hysteresis loop of the piezoelectric stack actuator is reduced, but the nonlinearity of output displacement is reduced by only 3%.
In summary, although the series structure and the analog driving mode of the existing stacked piezoelectric material have the advantages of simple structure, convenient driving, high output precision and the like, the practical application of the stacked piezoelectric material is severely limited by the defects of hysteresis nonlinearity of input and output, poor working reliability, serious heating, poor anti-interference capability and the like, especially the fields of aerospace and the like which have higher requirements on the reliability and the anti-interference capability of the motor converter.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the defects, the digital self-induction piezoelectric stacking device of the binary coding can realize continuous stepped adjustment of output displacement of the stacking type piezoelectric material through a digital driving signal, and has strong working reliability; the piezoelectric stack closed-loop control and precision compensation can be realized, hysteresis is eliminated, and the anti-interference capability is strong. Meanwhile, the invention also provides a working method of the binary coded digital self-induction piezoelectric stack device, and provides a working method of the piezoelectric stack device with high reliability and anti-interference capability.
The technical scheme is as follows: in order to solve the above problems, the present invention provides a binary coded digital self-induced piezoelectric stack device, comprising: the device comprises a self-induction unit, a compensation unit, a digital driving unit and a digital control unit;
the digital driving unit comprises a plurality of pieces of third piezoelectric materials which are axially overlapped and divided into n stages, wherein n is an integer; for outputting the displacement; the compensation unit comprises a single piece of second piezoelectric material, and the self-induction unit comprises a single piece of first piezoelectric material; the digital driving unit is arranged on the compensation unit, and the compensation unit is arranged on the self-induction unit; the compensation unit is used for performing precision compensation on the displacement output by the digital driving unit according to the precision compensation signal; the self-induction unit is used for sensing the output displacement of the digital driving unit; the digital control unit outputs a binary coded digital driving signal to drive the digital driving unit to output displacement; the digital control unit collects the output of the self-induction unit and generates a binary coded digital control signal and a precision compensation signal by combining the reference displacement signal; the digital control unit transmits the precision compensation signal to the compensation unit; the digital control unit outputs a digital control signal to the digital drive unit to realize closed-loop control.
Further, the number of the third piezoelectric materials per stage in the digital driving unit is 2nAnd 1 piece of piezoelectric material is increased step by step according to binary arrangement, so that continuous step adjustment of output displacement of the stacked piezoelectric material is realized.
Furthermore, the positive electrode and the negative electrode of each stage of third piezoelectric material are connected to form series connection; the stages are radially superposed to form parallel drive.
Furthermore, the digital control unit specifically comprises an acquisition module, a digital output module and a motion control module; the acquisition module is used for acquiring the voltage signal output by the self-induction unit, converting the voltage signal into actual displacement and comparing the actual displacement with a reference displacement signal to obtain an error; the motion control module is used for carrying out logic judgment and operation according to the error to generate a binary coded digital control signal and a precision compensation signal; the digital output module is used for outputting a digital control signal and a precision compensation signal.
Furthermore, the number of the output ports of the digital output module is the same as the number of the stages of the digital driving units.
Furthermore, the compensation unit has two working modes, wherein the working mode 1 is used for performing precision compensation on the displacement output by the digital driving unit according to the precision compensation signal, and the working mode 2 is used for replacing a faulty piezoelectric material in the digital driving unit; the digital control unit further comprises a fault diagnosis module, the fault diagnosis module is used for judging the working state of the stacked piezoelectric materials in the digital driving unit in real time, and if the stacked piezoelectric materials have faults, the compensation unit is switched to the working mode 2.
Furthermore, the thicknesses of the self-induction unit and the compensation unit are adjustable according to actual working conditions.
In addition, the invention provides a working method of the binary coded digital self-induction piezoelectric stack device, which is characterized by comprising the following steps of:
(1) giving a reference displacement signal, outputting a binary coded digital driving signal according to a reference displacement signal digital control unit, and driving a digital driving unit to output displacement;
(2) the self-sensing unit is extruded by the digital driving unit, and an induced electric field is generated due to the direct piezoelectric effect to output induced voltage;
(3) the digital control unit collects the voltage signal output by the self-sensing unit, converts the voltage signal into actual displacement and compares the actual displacement with a given reference displacement signal to obtain an error; the motion control module carries out logic judgment and operation according to the error to generate a binary coded digital control signal and a precision compensation signal; the digital output module outputs a digital control signal to the digital drive unit to realize the closed-loop control of the device; the motion control module outputs a precision compensation signal to the compensation unit, and the compensation unit performs precision compensation on the displacement output by the digital driving unit.
Further, the step (3) further comprises the step of judging the working state of the stacked piezoelectric material in real time through a fault diagnosis module of the digital control unit, and if the stacked piezoelectric material has a fault, switching the compensation unit to the working mode 2, so that the compensation unit replaces the faulty piezoelectric piece to work.
Has the advantages that: compared with the prior art, the digital self-induction piezoelectric stack device with binary coding has the remarkable advantages that: the displacement output is realized by arranging an n-level binary piezoelectric stack structure of a digital driving unit; the accuracy compensation of output displacement is realized by arranging a single piezoelectric material of the compensation unit, and the piezoelectric sheet works in the failure era of the digital piezoelectric stack; sensing the output displacement of the piezoelectric stack by a single piece of piezoelectric material provided with a self-induction unit; finally, the digital control unit is used for realizing the binary coding stepped adjustment, closed-loop control, precision compensation and fault diagnosis of the output displacement of the piezoelectric stack, so that the piezoelectric stack device with high working reliability and high anti-interference capability is obtained. Compared with the prior art, the working method of the binary coded digital self-induction piezoelectric stack device provided by the invention is a working method of the piezoelectric stack device with high reliability and anti-interference capability.
Drawings
FIG. 1 is a schematic diagram of a binary coded digital self-induction piezoelectric stack and its digital control system;
FIG. 2 is a schematic diagram of the displacement output of a digital piezoelectric stack;
FIG. 3 is a graph of digital piezoelectric stack displacement versus control signal;
fig. 4 is a schematic diagram of the generation of the digital control signal and the precision compensation signal in this embodiment.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
As shown in fig. 1, the present invention employs a binary coded digital self-induction piezoelectric stack device, comprising: the self-induction unit 1, the compensation unit 2, the digital drive unit 3 and the digital control unit 4.
The digital driving unit 3 is formed by axially superposing n stages of flaky third piezoelectric materials, and the quantity of the flaky third piezoelectric materials stacked at each stage is 2n1 slice, i.e. increasing in steps according to a binary arrangement. As shown in fig. 2, the positive electrode and the negative electrode of each stage of the third sheet-shaped piezoelectric material are connected with each other to form a series connection, and the stages are radially overlapped to form a parallel drive. The digital driving unit 3 outputs displacement under the driving of the digital control unit 4 outputting binary coded digital driving signals.
The compensation unit 2 is composed of a single piece of second piezoelectric material, and the thickness of the compensation unit is adjustable according to actual working conditions; the digital drive unit 3 is mounted on the compensation unit 2. The compensation unit 2 has two modes of operation: mode 1 and mode 2 of operation. Wherein, the working mode 1: the compensation unit 2 works under the drive of the precision compensation signal output by the digital control unit 4, and carries out precision compensation on the displacement output by the digital drive unit 3, so that the displacement output precision of the digital piezoelectric stack is improved; the working mode 2 is as follows: the piezoelectric material replaces the fault piezoelectric material in the digital driving unit 3, and works under the driving of the digital control signal output by the digital controller 4, so that the displacement output reliability of the digital piezoelectric stack is ensured.
The self-induction unit 1 is made of a single piece of first piezoelectric material, and the thickness of the self-induction unit is adjustable according to actual working conditions; the compensation unit 2 is mounted on the self-induction unit 1. The self-induction unit 1 is used for sensing the output displacement of the digital driving unit 3.
The digital control unit 4 is respectively connected with the digital driving unit 3, the compensation unit 2 and the self-induction unit 1 through I/O ports. The digital control unit 4 specifically comprises an acquisition module, a digital output module and a motion control module. The number of output ports in the digital output module is n, the number of the output ports is determined by the number of stages of the digital driving unit 3, and one stage of piezoelectric material correspondingly outputs one output port.
The invention relates to a working method of a binary coded digital self-induction piezoelectric stack device, which specifically comprises the following steps of:
(1) and (3) piezoelectric stack displacement output: giving a reference displacement signal; according to the reference displacement signal, the digital control unit outputs a binary coded digital driving signal; opening each stage of piezoelectric stack driving switches of the digital driving unit, enabling driving voltage to act on positive and negative stages of stacked piezoelectric materials to form a driving electric field, and enabling the digital driving unit to output displacement;
(2) displacement amplitude self-perception: the self-sensing unit is extruded by the digital driving unit, and an induction electric field is generated by the positive piezoelectric effect to output induction voltage;
(3) closed-loop control and precision compensation: the digital control unit collects the voltage signal output by the self-sensing unit, converts the voltage signal into actual displacement and compares the actual displacement with a given reference displacement signal to obtain an error; the motion control module carries out logic judgment and operation according to the error to generate a binary coded digital control signal and a precision compensation signal; the digital output module outputs a digital control signal to the digital drive unit to realize the closed-loop control of the device; and outputting a precision compensation signal to the compensation unit through the motion control module, and performing precision compensation on the displacement output by the digital driving unit through the compensation unit.
As shown in FIGS. 3 and 4, for a four-level binary piezoelectric stack structure, the given reference displacement signal is εrAt the beginning, the actual displacement is 0, and the error is 14.3 δ by comparison; the digital output module outputs a digital control signal 14 delta to the digital driving unit, the digital control signal enters the controller and outputs a digital control signal 0111, and the digital control signal opens switches of a position 2, a position 3 and a position 4 to carry out binary coding step regulation; if the output precision compensation signal is an analog voltage quantity, the control compensation unit 2 outputs 0.3 delta displacement to enable the total displacement to reach 14.3 delta and reach a specified position. When vibration occurs, the self-sensing unit senses that the actual displacement is 12 delta and the error is 2.3 delta, the digital output module outputs a digital control signal 2 delta to the digital driving unit and outputs a digital control signal 0100, and the signal opens a position 2 to perform binary coding step adjustment; and controlling the compensation unit to output 0.3 delta displacement to reach the specified position again. Fault diagnosis and elimination: the working state of the stacked piezoelectric materials in the digital driving unit is judged in real time through a fault diagnosis module of the digital control unit, if the stacked piezoelectric materials have faults, the compensation unit is switched to a working mode 2, and the compensation unit replaces a faulty piezoelectric piece to work.

Claims (9)

1. A binary coded digital self-induced piezoelectric stack arrangement, comprising: the device comprises a self-induction unit (1), a compensation unit (2), a digital driving unit (3) and a digital control unit (4);
the digital driving unit (3) comprises a plurality of pieces of third piezoelectric materials which are axially overlapped and divided into n stages, wherein n is a positive integer; for outputting the displacement;
the compensation unit (2) comprises a single piece of second piezoelectric material, and the self-induction unit (1) comprises a single piece of first piezoelectric material; the digital driving unit (3) is arranged on the compensation unit (2), and the compensation unit (2) is arranged on the self-induction unit (1); the compensation unit (2) is used for performing precision compensation on the displacement output by the digital driving unit (3) according to the precision compensation signal; the self-induction unit (1) is used for sensing the output displacement of the digital drive unit (3);
the digital control unit (4) outputs a binary coded digital driving signal to drive the digital driving unit (3) to output displacement; the digital control unit (4) collects the output of the self-induction unit (1) and generates a binary coded digital control signal and a precision compensation signal by combining a reference displacement signal; the digital control unit (4) transmits the precision compensation signal to the compensation unit (2); the digital control unit (4) outputs a digital control signal to the digital drive unit (3) to realize closed-loop control.
2. The binary coded digital self-induction piezoelectric stack device according to claim 1, wherein the number of the third piezoelectric materials per stage in the digital driving unit (3) is 2n-1 tablet.
3. The binary coded digital self-induction piezoelectric stack device according to claim 2, wherein the third piezoelectric materials of each stage are connected in series by connecting the positive electrode and the negative electrode; the stages are radially superposed to form parallel drive.
4. The binary coded digital self-induction piezoelectric stack device according to claim 1, wherein the digital control unit (4) specifically comprises an acquisition module, a digital output module, and a motion control module; the acquisition module is used for acquiring a voltage signal output by the self-induction unit (1), converting the voltage signal into actual displacement and comparing the actual displacement with a reference displacement signal to obtain an error; the motion control module is used for carrying out logic judgment and operation according to the error to generate a binary coded digital control signal and a precision compensation signal; the digital output module is used for outputting a digital control signal and a precision compensation signal.
5. The binary coded digital self-induction piezoelectric stack device according to claim 4, wherein the number of output ports of the digital output module is the same as the number of stages of the digital driving unit (3).
6. The binary coded digital self-induction piezoelectric stack device according to claim 4, wherein the compensation unit (2) has two operation modes, wherein the operation mode 1 is used for performing precision compensation on the output displacement of the digital driving unit (3) according to the precision compensation signal, and the operation mode 2 is used for replacing a failed piezoelectric material in the digital driving unit (3); the digital control unit (4) further comprises a fault diagnosis module, the fault diagnosis module is used for judging the working state of the stacked piezoelectric materials in the digital driving unit (3) in real time, and if the stacked piezoelectric materials have faults, the compensation unit (2) is switched to the working mode 2.
7. The binary coded digital self-induction piezoelectric stack device according to claim 1, wherein the thicknesses of the self-induction unit (1) and the compensation unit (2) are adjustable according to actual working conditions.
8. A method of operating a binary coded digital self-induced piezoelectric stack apparatus as claimed in claim 6, comprising the steps of:
(1) giving a reference displacement signal, outputting a binary coded digital driving signal by the digital control unit according to the reference displacement signal, and driving the digital driving unit to output displacement;
(2) the self-sensing unit is extruded by the digital driving unit, and an induction electric field is generated by the positive piezoelectric effect to output induction voltage;
(3) the digital control unit collects the voltage signal output by the self-sensing unit, converts the voltage signal into actual displacement and compares the actual displacement with a given reference displacement signal to obtain an error; the motion control module carries out logic judgment and operation according to the error to generate a binary coded digital control signal and a precision compensation signal; the digital output module outputs a digital control signal to the digital drive unit to realize the closed-loop control of the device; the motion control module outputs a precision compensation signal to the compensation unit, and the compensation unit performs precision compensation on the displacement output by the digital driving unit.
9. The operating method of the binary-coded digital self-induction piezoelectric stack device according to claim 8, wherein the step (3) further comprises the step of judging the operating state of the stacked piezoelectric material in real time through a fault diagnosis module of the digital control unit, and if the stacked piezoelectric material has a fault, switching the compensation unit to the operating mode 2, and enabling the compensation unit to work instead of the faulty piezoelectric sheet.
CN202210167766.3A 2022-02-23 2022-02-23 Binary coded digital self-induction piezoelectric stack device and working method Pending CN114637195A (en)

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