Temperature-resistant digital piezoelectric actuator and driving method thereof

Abstract

The application discloses a temperature-resistant digital piezoelectric actuator and a driving method thereof, and belongs to the technical field of intelligent material actuators. The piezoelectric actuator comprises an adjusting screw, a sleeve, a composite piezoelectric stack, an output rod, a disc spring, a twist-proof cover and a pre-tightening end cover. The composite piezoelectric stack is composed of n layers of composite piezoelectric axial stacks, each layer being composed of piezoelectric materials with different dielectric properties in a target temperature range, so that the dielectric stability characteristics in a wide temperature range are ensured. The output rod realizes the sensing and closed-loop control of the output displacement of the actuator. The total number of control ports of the actuator is 15, and the distributed digital control is realized by digital signal driving in the form of digital coding according to equivalent coding. The application is suitable for the fields with high requirements for the reliability, anti-interference ability, output displacement and control precision of motor converters in a wide temperature range under the working environment of temperature change, such as ultra-precision machining, micro-nano operation, aerospace electro-hydraulic servo control and precision actuation.

Description

Technical Field

[0001] This invention relates to a temperature-resistant digital piezoelectric actuator and its driving method, belonging to the field of smart material actuator technology. Background Technology

[0002] A motor-to-electrical converter (MTC) is a device that enables the conversion between electrical and mechanical energy. Piezoelectric materials, as intelligent materials that achieve electro-mechanical conversion through their piezoelectric effect, are widely used in aerospace precision actuation, micro-nano manipulation and positioning, micro-nano assembly, ultrasonic generators, and active vibration control due to their advantages such as high frequency response, small size, and large output force. For example, in ultra-precision machining, stacked piezoelectric actuators are used in high-speed servo tool systems to drive flexible hinge mechanisms, thereby achieving micro-feeding; in micro-nano manipulation, stacked piezoelectric actuators are used to drive flexible hinge mechanisms as grippers, and cantilever beam piezoelectric actuators are used as grippers to form micro-grippers, enabling the picking, handling, and assembly of micro-parts and components in MEMS; in biomedical engineering, piezoelectric actuator-driven micro-positioning platforms serve as cell-bearing mechanisms, facilitating micro-manipulation such as cell capture and release; and in aerospace precision actuation, piezoelectric actuators are often used to drive hydraulic valves in electro-hydraulic systems, enabling high-frequency response of hydraulic components. In these applications, the performance of the piezoelectric motor converter, i.e., the piezoelectric actuator, made of piezoelectric materials, directly affects the system performance and reliability.

[0003] Currently, under the operating conditions of a wide temperature range (-60-150℃) and high frequency, the performance of piezoelectric actuators often changes due to temperature variations, affecting their driving capability. Meanwhile, traditional electromagnetic actuators typically have a bandwidth of less than 400 Hz, failing to meet high-frequency requirements. In contrast, smart material actuators offer the advantage of high bandwidth (>1000 Hz). Magnetostrictive materials, with their relatively high Curie temperature (380℃), can, to some extent, meet the wide temperature range requirement. However, magnetostrictive actuators involve two-stage electro-magnetic-mechanical conversion, and the constant current power supply, excitation coil, and permanent magnet required to drive such actuators result in a complex structure and low energy conversion efficiency. Compared to magnetostrictive materials, piezoelectric materials achieve direct electro-mechanical conversion, offering advantages such as simple structure, high energy utilization, and a more compact structure, making them more suitable for applications with limited space, high driving precision, and high energy utilization. However, piezoelectric materials are limited by their relatively low Curie temperature (mostly below 100℃), making them unsuitable for high-temperature environments. With the development and advancement of high-temperature piezoelectric material formulations and sintering processes, high-temperature piezoelectric ceramic materials with a Curie temperature of up to 510 ℃ have been developed in recent years, leading to broader application prospects for high-frequency actuators based on piezoelectric ceramics. However, within a wide temperature range, the stability of various properties of piezoelectric materials is difficult to guarantee with changes in ambient temperature. To better apply them to operating conditions with drastic changes in internal ambient temperature, the consistency and stability of the output performance of piezoelectric actuators across a wide temperature range is a problem that urgently needs to be solved.

[0004] To address the issues of output performance variations and inconsistencies in piezoelectric actuators caused by temperature changes over a wide temperature range, it is necessary to consider how to achieve stable and consistent output from the perspectives of piezoelectric actuator structure, drive method, and control method.

[0005] In terms of actuator structure, current piezoelectric actuators often employ a stacked configuration, where piezoelectric sheets of equal thickness are axially stacked to achieve large displacement output. However, this structure cannot address the impact of temperature variations on the performance of the piezoelectric material itself.

[0006] In terms of the driving method, for stacked piezoelectric actuators, an electrically parallel structure is adopted, that is, excitation voltage is applied to each piezoelectric material simultaneously, and they are driven at the same time. The advantage of simultaneous driving is that the drive system structure is simple, requiring only one signal generator and power amplifier. The disadvantage is poor reliability; if the output performance of one layer of piezoelectric material in the stack is affected by temperature changes during operation, the output performance of the entire piezoelectric stack will be affected.

[0007] Regarding the driving signal, existing stacked piezoelectric materials all use analog signals. The advantages of analog driving signals are high driving accuracy and easy implementation of closed-loop position control. The disadvantages are severe hysteresis nonlinearity, poor anti-interference ability, and the need to design complex control strategies to overcome electromagnetic interference in the working environment.

[0008] In summary, while the existing series structure of stacked piezoelectric materials and its simulation and parallel driving methods have advantages such as simple structure, convenient driving, large output displacement and high precision, their output performance is limited by the characteristics of the actuator structure and driving. Under wide temperature range temperature changes, the performance of piezoelectric materials is unstable due to temperature, the stacking generates serious heat, and the working reliability is poor. These shortcomings severely limit the practical application of stacked piezoelectric materials, especially in fields such as precision driving and micro-nano manipulation, where the reliability and anti-interference ability of motor converters are highly required. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a temperature-resistant digital piezoelectric actuator and its driving method, which can achieve temperature resistance over a wide temperature range and, through digital driving signals, enable continuous and stepped adjustment of the output displacement of the stacked piezoelectric material.

[0010] A temperature-resistant digital piezoelectric actuator is characterized in that: the piezoelectric actuator is symmetrical along the central axis and includes a motor converter and a composite piezoelectric stack; the motor converter includes a hollow sleeve with an adjusting screw at the top and a pre-tightening end cap at the bottom, and an output rod located on the upper part of the pre-tightening end cap and extending outward through the pre-tightening end cap;

[0011] The composite piezoelectric stack is coaxially positioned between the adjusting screw and the output rod, driving the output rod to reciprocate in the output direction of the composite piezoelectric stack.

[0012] Preferably, the composite piezoelectric stack includes sheet-like piezoelectric materials with different dielectric properties within the target temperature range. Specifically, the composite piezoelectric stack is formed by axially stacking n layers of composite piezoelectric materials. The composite piezoelectric material is a set of sheet-like piezoelectric units, which are formed by connecting the positive and negative electrodes of sheet-like piezoelectric materials with opposite dielectric properties within the temperature range in series. Sheet-like piezoelectric units with different temperature ranges are selected and stacked to form a composite piezoelectric stack.

[0013] Preferably, the side of the composite piezoelectric stack that contacts the upper adjusting screw is the fixed end, and the side of the composite piezoelectric stack near the pre-tightening end cap is the output end. The output end drives the external component to reciprocate through the output rod.

[0014] Preferably, the output rod is an integral composite structure consisting of an upper stepped frustum and a lower round rod. Matching anti-twist caps are snapped onto both ends of the stepped frustum to prevent the piezoelectric material output end from being damaged by external torque during output force and displacement. The anti-twist caps are in contact with the inner wall surface of the hollow sleeve.

[0015] Preferably, a disc spring is fitted on the output rod, and the disc spring is located on the upper part of the pre-tightening end cover and fitted onto the round part of the output rod.

[0016] This invention also discloses a driving method for a temperature-sensitive digital piezoelectric actuator, comprising the following steps:

[0017] Step 1, Actuator Displacement Output: By discretizing the composite piezoelectric stack, the composite piezoelectric is equivalently encoded; Step 2, Distributed digital control is adopted to reasonably allocate the working position of the output displacement according to the heating condition and output performance of the piezoelectric stack; Step 3, the corresponding working position is driven by the digital signal based on the equivalent encoding to realize the adjustment of the output displacement, and the actuator output displacement is sensed through the output rod to realize closed-loop control and accuracy compensation.

[0018] Preferably, the actuator displacement output in step 1 is as follows: given a reference displacement signal, the digital control unit outputs an equivalent encoded digital drive signal to turn on the drive switches of each layer of the composite piezoelectric stack. The drive voltage acts on the positive and negative poles of the working piezoelectric layer to form a drive electric field, and the composite piezoelectric stack outputs displacement.

[0019] As a preferred option, step 2, distributed digital control, specifically involves: releasing the control degrees of freedom through discrete piezoelectric stacks and digitally encoding and underactuating them, so that each piezoelectric layer can work intermittently. For output displacement control requirements with large displacement and small fluctuations, continuous displacement is simulated by step displacement output through digital signals. At the same time, the digital signals are not affected by complex electromagnetic waves, thus improving the reliability of the system.

[0020] The specific process is as follows:

[0021] Actuator displacement output: Given a reference displacement signal, the digital control unit outputs an equivalent encoded digital drive signal to turn on the drive switches of the composite piezoelectric layers of the piezoelectric stack. The drive voltage acts on the positive and negative terminals of the working piezoelectric layer to form a drive electric field, and the piezoelectric stack outputs displacement.

[0022] Distributed digital control: By using discrete piezoelectric stacks, the control degrees of freedom are released and digitally encoded and underactuated, meaning that each piezoelectric layer can work intermittently. For output displacement control requirements with large displacement and small fluctuations, the continuous displacement is simulated by step displacement output through digital signals. At the same time, the digital signals are not affected by complex electromagnetic waves, which can improve the reliability of the system.

[0023] Closed-loop control and accuracy compensation: The output displacement signal of output rod 5 is acquired by the digital control unit, converted into actual displacement, and compared with a given reference displacement signal to obtain the error. The motion control module performs logical judgment and calculation. Specifically, if there is a relative error between the output displacement of the digital piezoelectric actuator and the relative reference displacement signal, the error value is processed by the controller. Based on the piezoelectric stack displacement output model and interlayer temperature rise model, the controller judges the piezoelectric sheet displacement output and diagnoses faults. Subsequently, based on this working condition, the controller, after performing relevant logical judgments and calculations, determines the corresponding actuation layer and arranges a reasonable drive strategy, thereby generating equivalent encoded digital control signals and accuracy compensation signals. Finally, the control signal is output through the digital output module to achieve closed-loop control and accuracy compensation of the actuator. The specific implementation process uses a 15-layer piezoelectric sheet as an example.

[0024] By encoding the 15-layer piezoelectric elements with 15 bits, different control combinations can be used to rationally allocate the working position of the output displacement for different output displacement requirements and piezoelectric element heating conditions. Furthermore, digital control can be used to rationally allocate the control voltage, reducing self-heating and optimizing heat distribution within the stack. After inputting digital signals to the working piezoelectric layers, the range of output displacement variation increases with the number of energized layers. Simultaneous driving of all 15 piezoelectric elements allows for the achievement of the maximum displacement value.

[0025] Beneficial effects:

[0026] (1) The present invention uses piezoelectric materials with different temperature ranges, which broadens the working temperature range of the piezoelectric actuator and improves its resistance to temperature changes over a wide temperature range;

[0027] (2) By discretizing the composite piezoelectric stack, the driving signal is converted from an electrical signal to a digital signal, which improves the anti-interference capability of the signal and alleviates the hysteresis nonlinearity caused by the analog signal driving the piezoelectric actuator, thereby improving the output accuracy of the actuator.

[0028] (3) The present invention realizes distributed digital control of stacked piezoelectric materials. After releasing the control degree of freedom, the drive rod realizes the continuous and stepped adjustment of the output displacement of the stacked piezoelectric materials.

[0029] (4) By discretizing the composite piezoelectric stack, the present invention can combine different coding and control strategies to realize digital drive, which is easier to realize intelligently compared with the traditional analog signal drive method.

[0030] (5) The present invention rationally allocates the working layer and control voltage through digital coding and switching strategies, reduces self-generated heat and optimizes the heat distribution in the stack, thereby improving the service life and output displacement consistency of the piezoelectric actuator. Attached Figure Description

[0031] Figure 1This is a structural diagram of a temperature-resistant digital piezoelectric actuator according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of a temperature-resistant digital piezoelectric actuator and its driving method according to an embodiment of the present invention.

[0033] Figure 3 This is an equivalent-encoded digital piezoelectric stack displacement output diagram according to an embodiment of the present invention;

[0034] Figure label:

[0035] 1 Piezoelectric actuator, 2 Adjusting screw, 3 Sleeve, 4 Composite piezoelectric stack, 5 Output rod, 6 Disc spring, 7 Anti-torsion cover, 8 Preload end cover, 9 Composite piezoelectric. Detailed Implementation

[0036] To more intuitively and clearly illustrate the structural principles and driving methods in the embodiments of the present invention, the following description will be based on the accompanying drawings. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] like Figures 1 to 3 As shown, embodiments of the present invention provide a temperature-resistant digital piezoelectric actuator and its driving method. It utilizes a multi-material composite piezoelectric layer to achieve wide-temperature-range resistance to temperature variations, and enables continuous, stepped adjustment of the output displacement of the stacked piezoelectric material via digital driving signals. To achieve the above objectives, embodiments of the present invention employ the following technical solutions:

[0038] A temperature-resistant digital piezoelectric actuator structure as follows Figure 1 As shown, the piezoelectric actuator 1 includes a motor converter and a composite piezoelectric stack 4. The entire piezoelectric actuator 1 is symmetrical about the central axis. The motor converter includes a sleeve 3, an adjusting screw 2 installed on the upper end of the sleeve 3, an anti-twist cover 7 and a pre-tightening end cover 8 installed on the lower end of the sleeve 3, an output rod 5 installed in the anti-twist cover 7 and the pre-tightening end cover 8, and a disc spring 6 installed in the pre-tightening end cover 8 and the output rod 5.

[0039] The composite piezoelectric stack 4 is installed between the adjusting screw 2 and the output rod 5. The side of the composite piezoelectric stack 4 that contacts the upper adjusting screw 2 is the fixed end, and the side of the composite piezoelectric stack 4 near the pre-tightening end cap 8 is the output end. The output end drives the external component to reciprocate through the output rod 5. Taking a 2-layer composite piezoelectric stack as an example, the specific implementation is as follows:

[0040] By comparing the dielectric temperature spectrum curves of existing piezoelectric materials, two piezoelectric materials with opposite trends in dielectric temperature curves are selected, i.e., their dielectric constants decrease and increase respectively within a certain temperature range. This achieves dielectric stability over a wide temperature range without sacrificing energy density and strain output.

[0041] This invention also discloses an equivalent encoding driving method for a temperature-variable digital piezoelectric actuator. By discretizing the composite piezoelectric stack (n layers with n pairs of positive and negative terminals), control degrees of freedom are released. The n piezoelectric layers are equivalently encoded, and the corresponding operating positions are driven by the equivalent encoded digital signals. Distributed digital control is employed to achieve underactuation of the actuator, allowing each piezoelectric layer to operate intermittently. Simultaneously, stepped displacement output via digital signals simulates continuous displacement. Closed-loop control and precision compensation are used to rationally allocate the operating positions of the output displacement based on the piezoelectric stack's heating characteristics and output performance, thus achieving output displacement adjustment. The actuator's output displacement is sensed and controlled in a closed-loop manner via an output rod.

[0042] Specifically,

[0043] Actuator displacement output: Given a reference displacement signal, the digital control unit outputs an equivalent encoded digital drive signal to turn on the drive switches of the composite piezoelectric layers of the piezoelectric stack. The drive voltage acts on the positive and negative terminals of the working piezoelectric layer to form a drive electric field, and the piezoelectric stack outputs displacement.

[0044] Distributed digital control: By using discrete piezoelectric stacks, the control degrees of freedom are released and digitally encoded and underactuated, meaning that each piezoelectric layer can work intermittently. For output displacement control requirements with large displacement and small fluctuations, the continuous displacement is simulated by step displacement output through digital signals. At the same time, the digital signals are not affected by complex electromagnetic waves, which can improve the reliability of the system.

[0045] The following design is for distributed digital control:

[0046] (1) Design of controller anti-temperature rise decision algorithm

[0047]

[0048] n: Total number of working piezoelectric positions, i: Piezoelectric layer number, p i : The working state of the piezoelectric layer, 0 is off, 1 is on.

[0049]

[0050] In the formula: The decision variable is the state of the n piezoelectric layers, including the on / off state p. i Electric field boundary condition B EiMechanical field boundary conditions B Fi ; The target space is represented by m target space functions Q. i (x i The model consists of i = 1, 2, ..., m, where Q represents the objective function, which is a function of the influence of the heat of the piezoelectric stack on the output. The optimization objective of the model is to ensure that the heat of each piezoelectric layer has the least impact on its own output characteristics.

[0051] (2) Design of controller anti-temperature rise control algorithm

[0052] Since the signal driving the digital piezoelectric actuator is a digital signal, the control duty cycle of n PWM signals can be designed based on the temperature rise model and displacement tracking error. :

[0053]

[0054] In the formula: e is the position tracking error

[0055] Specifically, a differential PWM controller based on differential PID can be used. The principle is to design n PWM signals to drive n layers of piezoelectric cells respectively. Taking the case of driving a single-layer piezoelectric cell as an example... This is the initial duty cycle of PWM-1. The actual duty cycle is adjusted based on this, as shown in the following formula:

[0056]

[0057] It controls the duty cycle; when the feedback position is the same as the desired position, The value is 0; when there is an error between the feedback position and the desired position, the control duty cycle is used. Adjustments were made.

[0058] Closed-loop control and accuracy compensation: The output displacement signal of output rod 5 is acquired by the digital control unit, converted into actual displacement, and compared with a given reference displacement signal to obtain the error. The motion control module performs logical judgment and calculation. Specifically, if there is a relative error between the output displacement of the digital piezoelectric actuator and the relative reference displacement signal, the error value is processed by the controller. Based on the piezoelectric stack displacement output model and interlayer temperature rise model, the controller judges the piezoelectric sheet displacement output and diagnoses faults. Subsequently, based on this working condition, the controller, after performing relevant logical judgments and calculations, determines the corresponding actuation layer and arranges a reasonable drive strategy, thereby generating equivalent encoded digital control signals and accuracy compensation signals. Finally, the control signal is output through the digital output module to achieve closed-loop control and accuracy compensation of the actuator. The specific implementation process uses a 15-layer piezoelectric sheet as an example.

[0059] A 15-bit encoding is used for the 15-layer piezoelectric element. For different output displacement requirements and piezoelectric element heating conditions, different control combinations can be used to rationally allocate the working position of the output displacement, and the control voltage can be rationally allocated through digital control to reduce self-heating and optimize heat distribution within the stack. For example, ideally, the output displacement of the piezoelectric layer at a 100V drive voltage is 's'. If a target output displacement of 5*s is required, a stack of 5 composite piezoelectric layers can be used as the working layers of the actuator to achieve this displacement. When the measured displacement output value is less than 5*s, the controller collects the error signal and performs logical judgment and decision-making: First, the corresponding drive voltage can be adjusted, i.e., the drive voltage is increased within the maximum working voltage range of the piezoelectric element. If the drive voltage has reached the maximum value of a single-layer composite piezoelectric element, it can be determined that the piezoelectric stack working layer still has temperature changes, affecting its output displacement. The controller can then sequentially drive the current 5 working layers to identify the temperature-changing layer. Subsequently, based on the actuator's temperature rise model, adjustments are made to the piezoelectric working layers, excitation duration, and switching frequency to ensure the actuator meets the drive requirements within a short time. After the controller completes its decision-making process, the system inputs a digital signal to the piezoelectric layer at the working position via the digital drive unit. Specifically, the digital signal is a square wave with a value between 0 and 1. When the piezoelectric layer needs to operate, it is given a high level; the amplitude and drive time are adjusted according to the tracking error and the controller's decision. When the piezoelectric layer does not need to operate, the output voltage amplitude is 0, ultimately achieving the target displacement. Furthermore, as the number of energized layers increases, the range of output displacement can be expanded; simultaneous drive of 15 piezoelectric elements can achieve the maximum displacement.

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A driving method of a temperature-variable-resistant digital piezoelectric actuator, characterized by, The piezoelectric actuator is symmetrical about the central axis and includes a motor converter and a composite piezoelectric stack. The motor converter includes a hollow sleeve (3), with an adjusting screw (2) at the top and a pre-tightening end cap (8) at the bottom. The output rod (5) is located on the upper part of the pre-tightening end cap (8) and extends outward through the pre-tightening end cap (8). The composite piezoelectric stack (4) is coaxially disposed between the adjusting screw (2) and the output rod (5), pushing the output rod (5) to reciprocate in the output direction of the composite piezoelectric stack (4); The driving method for this piezoelectric actuator includes the following steps: Step 1, actuator displacement output: By discretizing the composite piezoelectric stack (4), the composite piezoelectric (9) is encoded by equivalent value; Step 2 employs distributed digital control. Based on the heating characteristics and output performance of the piezoelectric stack, the operating position of the output displacement is rationally allocated. Specifically, by discretizing the piezoelectric stack, the control degrees of freedom are released, and digital encoding and underactuation are applied, allowing each piezoelectric layer to operate intermittently. For output displacement control requirements with large displacements and small fluctuations, continuous displacement is simulated through stepped displacement output using digital signals. Simultaneously, the digital signals are unaffected by complex electromagnetic interference, improving system reliability. The distributed digital control includes controller temperature rise-resistant decision-making and controller temperature rise-resistant control. The controller's temperature rise resistance decision algorithm is as follows: (1) The total number of piezoelectric elements n in the working position: , The objective function Q for the influence of heat from the piezoelectric stack on the output is: wherein are decision variables, i.e. the states of the n piezoelectric layers, including the on-off situation p i , electric field boundary conditions B Ei , mechanical field boundary conditions B Fi ; (2) The controller's anti-temperature rise control algorithm is as follows: Control duty cycle of n PWM signals : , e is a position tracking error; Step 3: Drive the corresponding working position based on the digital signal of equivalent encoding to realize the adjustment of output displacement, and sense the output displacement of the actuator through the output rod to realize closed-loop control and accuracy compensation.

2. The driving method of the temperature-variable-resistant digital piezoelectric actuator according to claim 1, wherein Step 1 actuator displacement output is as follows: given a reference displacement signal, the digital control unit outputs an equivalent encoded digital drive signal to turn on the drive switch of each layer of composite piezoelectric (9) of the composite piezoelectric stack (4). The drive voltage acts on the positive and negative poles of the working piezoelectric layer to form a drive electric field, and the composite piezoelectric stack (4) outputs displacement.

3. The driving method of the temperature-variable resistant digital piezoelectric actuator according to claim 1, wherein The composite piezoelectric stack (4) includes n layers of composite piezoelectric (9), corresponding to n pairs of positive and negative terminals. Encoding is achieved based on the positive and negative terminals, thereby releasing the control degrees of freedom and realizing discretization.

4. The driving method of the temperature-variable-resistant digital piezoelectric actuator according to claim 3, wherein Step 3, closed-loop control and precision compensation, specifically involves: acquiring the output displacement signal of the output rod (5) through the digital control unit, converting it into actual displacement, comparing it with the given reference displacement signal to obtain the error, and using the motion control module for logical judgment and calculation. That is, if there is a relative error between the output displacement of the digital piezoelectric actuator and the relative reference displacement signal, the error value is processed by the controller. Based on the piezoelectric stack displacement output model and the interlayer temperature rise model, the piezoelectric sheet displacement output situation is judged and fault diagnosis is performed. Then, based on the working situation, after performing relevant logical judgment and calculation, the controller decides on the corresponding actuation layer and arranges a reasonable driving strategy, thereby generating equivalent encoded digital control signals and precision compensation signals. Finally, the digital output module outputs digital control signals to realize the closed-loop control and precision compensation of the actuator.

5. The temperature-invariant driving method of a digital piezoelectric actuator according to any one of claims 1 to 4, characterized by, The composite piezoelectric stack (4) includes sheet piezoelectric materials with different dielectric properties within the target temperature range. Specifically, the composite piezoelectric stack (4) is formed by axially stacking n layers of composite piezoelectric (9). The composite piezoelectric (9) is a set of sheet piezoelectric units. The positive and negative poles of sheet piezoelectric materials with opposite dielectric properties within the temperature range are connected in series to form a set of sheet piezoelectric units. Sheet piezoelectric units with different temperature ranges are selected and stacked to form the composite piezoelectric stack (4).

6. The driving method of the temperature-variable-resistant digital piezoelectric actuator according to claim 5, wherein The side of the composite piezoelectric stack (4) that contacts the upper adjusting screw (2) is the fixed end, and the side of the composite piezoelectric stack (4) that is close to the pre-tightening end cap (8) is the output end. The output end drives the external component to reciprocate through the output rod (5).

7. The driving method of the temperature-variable resistant digital piezoelectric actuator according to claim 6, wherein The output rod (5) is an integral composite structure consisting of an upper stepped frustum and a lower round rod. Anti-twist caps (7) are snapped onto both ends of the stepped frustum to prevent the piezoelectric material output end from being damaged by external torque when outputting force and displacement. The anti-twist caps (7) are in contact with the inner wall of the hollow sleeve (3).

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