CN114221576B - Wheel type pre-compression low-frequency piezoelectric actuator based on flexible hinge structure and working method thereof - Google Patents

Abstract

The invention discloses a wheel type pre-compression low-frequency piezoelectric actuator based on a flexible hinge structure and a working method thereof. The first piezoelectric driving assembly, the second piezoelectric driving assembly and the base are integrally designed, the pre-pressure between the driving feet of the first piezoelectric driving assembly and the second piezoelectric driving assembly and the output shaft is regulated through the regulating wheel type pre-tightening mechanism, and the wheel type pre-tightening mechanism has the function of a linear bearing. The first piezoelectric driving component and the second piezoelectric driving component are driven to realize forward and reverse movement of the output shaft. The invention has the advantages of high reliability, simple structure, multiple groups of controllable, high precision, better universality, easy popularization and good economic benefit, and the wheel type pre-tightening mechanism has extremely high application value for pre-pressure assembly and adjustment of the piezoelectric stick-slip actuator.

Description

Wheeled preloaded low-frequency piezoelectric actuator based on flexible hinge structure and its working method

Technical field

The present invention relates to the field of piezoelectric drive, and in particular to a wheel-type preloaded low-frequency piezoelectric actuator based on a flexible hinge structure and a working method thereof.

Background technique

The piezoelectric stick-slip actuator device is a transmission device based on the inverse piezoelectric effect. Because of its fast response speed and high precision, it has extremely wide applications in the fields of biology, robotics and machinery manufacturing, especially micro-nano control. in applications. However, the stability during exercise is poor, resulting in a low market application rate. The main reason is that the preload force is variable. Currently, the commonly used method of applying the preload force is to use bolts or differential rulers to apply it at the tail of the stator. This rigid application method is easily affected by surface microscopic wear or assembly errors. Therefore, how to assemble and apply preload has become a major engineering problem faced by linear piezoelectric actuators to further broaden their application range and improve device performance.

Contents of the invention

The technical problem to be solved by the present invention is to provide a wheel-type preloaded low-frequency piezoelectric actuator based on a flexible hinge structure and a working method thereof in view of the defects involved in the background technology.

The present invention adopts the following technical solutions to solve the above technical problems:

A wheel-type preloaded low-frequency piezoelectric actuator based on a flexible hinge structure, including a base, a first piezoelectric drive component, a second piezoelectric drive component, a housing, an output shaft, and a wheel-type preload mechanism;

The base is provided with symmetrical first bevel and second bevel to form a V-shaped notch, and the first bevel and second bevel are symmetrically provided with threaded through holes perpendicular to the bevel;

The first piezoelectric driving component and the second piezoelectric driving component have the same structure, and both include preloaded bolts, gaskets, piezoelectric stacks, conductive blocks, deformation structural members and driving feet, wherein the conductive block, driving foot Each foot is a semi-cylinder, including a first end wall, a second end wall, a curved side wall and a flat side wall; the lower end surface of the piezoelectric stack and the upper end surface of the gasket are firmly connected, and the piezoelectric stack The upper end surface of the stack is fixedly connected to the planar side wall of the conductive block; the deformation structure is U-shaped and includes a top plate, first to second inclined plates, first to second flexible hinges, and first to second flexible hinges. Two side plates, the first side plate and the second side plate are arranged in parallel, and the upper ends of the first side plate and the second side plate respectively pass through the first flexible hinge, the second flexible hinge and one end of the first inclined plate. One end of the second inclined plate is connected correspondingly, and the other end of the first inclined plate and the other end of the second inclined plate are respectively connected with the two ends of the top plate; the flat side wall of the driving foot and the top plate The upper end surface is firmly connected;

The first piezoelectric driving assembly and the second piezoelectric driving assembly are symmetrically arranged on the first inclined plane and the second inclined plane, wherein the lower ends of the first side plate and the second side plate of the deformation structure of the first piezoelectric driving assembly are vertically connected to the first inclined surface, including the threaded holes on the first inclined surface; the preloaded bolts of the first piezoelectric driving assembly are threadedly connected to the threaded holes on the first inclined surface, extending into the first piezoelectric The lower end surface of the deformation structural member of the driving assembly resists the backing plate of the first piezoelectric driving assembly, so that the arc side wall of the conductive block of the first piezoelectric driving assembly and the lower end surface of the top plate of the deformation structural member of the first piezoelectric driving assembly offset ; The lower ends of the first side plate and the second side plate of the deformation structure of the second piezoelectric driving assembly are vertically connected to the second inclined plane, including the threaded holes on the second inclined plane; the second piezoelectric driving assembly The preloaded bolt is threadedly connected to the threaded hole on the second inclined surface, extends into the deformation structure of the second piezoelectric drive component, and resists the lower end surface of the second piezoelectric drive component pad, so that the second piezoelectric drive component The arc side wall of the conductive block offsets the lower end surface of the top plate of the deformation structure of the second piezoelectric driving component;

The deformation structural member of the first piezoelectric driving assembly, the deformation structural member of the second piezoelectric driving assembly, the conductive block of the first piezoelectric driving assembly, the conductive block of the second piezoelectric driving assembly, and the conductive block of the first piezoelectric driving assembly. The driving foot and the driving foot of the second piezoelectric driving component are on the same plane;

The housing is hollow and has a first through-slot communicated with its inner cavity on the upper end surface for containing the base, the first piezoelectric driving component and the second piezoelectric driving component, and allowing the third The driving feet of a piezoelectric driving component and a second piezoelectric driving component extend from the first through slot; the housing and the base are fixedly connected;

The wheel-type preloading mechanism includes a runner, a runner frame, m preload springs, and m preload bolts, where m is a natural number greater than or equal to 3;

The wheel includes a wheel body and a wheel axle, and the wheel body can freely rotate around the wheel axle;

The runner frame is in the shape of a flat plate, with a second through slot for the runner body to pass through, and m circumferentially provided through slots that match the pre-tightening bolts. hole;

The runner is arranged in the second through groove, and both ends of its wheel shaft are vertically connected to the side walls of the second through groove, so that part of the wheel body is located above the runner frame and part is located below the runner frame. And the wheel body can rotate freely in the second slot;

The upper end surface of the housing is provided with m threaded holes corresponding to the m preload bolts;

The output shaft is a rectangular parallelepiped and is arranged between the runner and the housing;

The m preload springs are placed on the m preload bolts in one-to-one correspondence; the m preload bolts pass through their corresponding through holes on the runner frame and engage with their corresponding threads on the housing. The holes are threadedly connected, and one end of the preload spring on it is against its nut, and one end is against the upper end surface of the runner frame, so that the driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component It offsets the lower end surface of the output shaft, and the upper end surface of the runner and the output shaft between the driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component offset; the runner and the The driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component are on the same plane.

As a further optimization solution of the wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure of the present invention, the output shaft is provided with a friction layer made of ceramic material to improve the friction between the runner and the output shaft. and output shaft wear resistance.

As a further optimization solution of the wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure of the present invention, the deformation structural members of the first and second piezoelectric driving components are made of aluminum alloy, spring steel or brass. made of.

As a further optimization solution of the wheel-type pre-loaded low-frequency piezoelectric actuator based on the flexible hinge structure of the present invention, the driving feet of the first and second piezoelectric driving components are made of alumina ceramic materials or zirconia ceramic materials. In order to increase the friction during friction driving and improve the service life.

The invention also discloses a working method of the wheel-type preloaded low-frequency piezoelectric actuator based on a flexible hinge structure, which includes the following steps:

If you need to drive the output shaft to move forward:

Step A.1), adjust the first to fourth preload bolts so that the runner applies preload Fn to the output shaft;

Step A.2), use a rising triangular wave to drive the piezoelectric stack of the first piezoelectric driving component for T1 seconds to extend it by L1, and at the same time control the piezoelectric stack of the second piezoelectric driving component to maintain its original length. At this time The output shaft is pushed forward by the first piezoelectric driving component by a distance of x ₁ under the action of static friction, and at the same time, the runner rotates forward through an angle θ1;

Step A.3), use a descending triangular wave drive to drive the piezoelectric stack of the first piezoelectric drive component for T2 seconds, causing it to shrink back to its original length. T2 is smaller than T1, and the output shaft is pressed by the first piezoelectric stack under the action of sliding friction. The electric drive component pulls the distance x ₂ in the opposite direction, and at the same time, the runner reversely rotates through the angle θ2;

Step A.4), repeat steps A.2) to step A.3) to make the output shaft continuously make positive stick-slip steps, and the step length of each cycle is x ₁ - x ₂ ;

If you need to drive the output shaft to move in reverse:

Step B.1), adjust the first to fourth preload bolts so that the runner applies preload Fn to the output shaft;

Step B.2), use a rising triangular wave to drive the piezoelectric stack of the second piezoelectric driving component for T1 seconds to extend it by L1, and at the same time control the piezoelectric stack of the first piezoelectric driving component to maintain its original length. At this time The output shaft is pushed backward by the second piezoelectric driving component by a distance of x ₁ under the action of static friction, and at the same time, the runner reversely rotates through an angle θ1;

Step B.3), use a descending triangular wave to drive the piezoelectric stack of the second piezoelectric drive component for T2 seconds, causing it to shrink back to its original length. T2 is smaller than T1, and the output shaft is driven by the second piezoelectric stack under the action of sliding friction. The driving component pulls the distance x ₂ forward, and at the same time, the runner rotates forward through the angle θ2;

Step B.4), repeat steps B.2) to step B.3), so that the output shaft continuously makes reverse stick-slip steps, and the step length of each cycle is x ₁ - x ₂ .

As a further optimization solution for the working method of the wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure of the present invention, the T1:T2=9:1.

Compared with the existing technology, the present invention adopts the above technical solution and has the following technical effects:

1. The present invention achieves forward and reverse bidirectional motion output by arranging at least two sets of piezoelectric drive modules with opposite directions. Since the piezoelectric drive modules are installed in the base using an embedded design, there are fewer structural assembly parts, which effectively reduces Assembly errors, and the output stroke of the device can be adjusted according to the selection of different numbers of piezoelectric drive modules or output shaft strokes;

2. The present invention adopts a wheel-type preloading scheme. The preloading force application is optimized from the traditional method of setting a differential ruler or bolts at the base to applying it at the output shaft, which has better stability and thus achieves the effect of preloading. , and there is no need to install separate bearings on the output shaft, which has certain guiding value for the assembly method of stick-slip drives.

Description of the drawings

Figure 1 is a schematic structural diagram of the present invention;

Figure 2 is a schematic structural diagram of the present invention with the casing removed;

Figure 3 is a schematic structural diagram of the deformation structure of the first and second piezoelectric driving components and the base in the present invention;

Figure 4 is a schematic structural diagram of the wheel-type pretensioning mechanism in the present invention;

Figure 5 is a schematic structural diagram of the housing in the present invention;

Figure 6 is a schematic diagram of the forward driving principle of the present invention;

Figure 7 is a schematic diagram of the reverse driving principle of the present invention;

Figure 8 is a schematic diagram of driving a triangular wave in the present invention.

In the figure, 1-output shaft, 2-preload bolt, 3-runner frame, 4-runner axle, 5-runner wheel body, 6-preload spring, 7-first piezoelectric drive assembly Conducting block, 8-driving foot of the second piezoelectric driving component, 9-base, 10-preloading bolt of the first piezoelectric driving component, 11-piezoelectric stack of the second piezoelectric driving component, 12- Spacer for the second piezoelectric actuation assembly.

Detailed ways

The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings:

The invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, components are exaggerated for clarity.

As shown in Figures 1 and 2, the present invention discloses a wheel-type pre-pressure low-frequency piezoelectric actuator based on a flexible hinge structure, including a base, a first piezoelectric drive component, a second piezoelectric drive component, Housing, output shaft, and wheel preload mechanism;

The base is provided with symmetrical first bevel and second bevel to form a V-shaped notch, and the first bevel and second bevel are symmetrically provided with threaded through holes perpendicular to the bevel;

The first piezoelectric driving component and the second piezoelectric driving component have the same structure, and both include preloaded bolts, gaskets, piezoelectric stacks, conductive blocks, deformation structural members and driving feet, wherein the conductive block, driving foot Each foot is a semi-cylinder, including a first end wall, a second end wall, a curved side wall and a flat side wall; the lower end surface of the piezoelectric stack and the upper end surface of the gasket are firmly connected, and the piezoelectric stack The upper end surface of the stack is fixedly connected to the planar side wall of the conductive block; the deformation structure is U-shaped and includes a top plate, first to second inclined plates, first to second flexible hinges, and first to second flexible hinges. Two side plates, the first side plate and the second side plate are arranged in parallel, and the upper ends of the first side plate and the second side plate respectively pass through the first flexible hinge, the second flexible hinge and one end of the first inclined plate. One end of the second inclined plate is connected correspondingly, and the other end of the first inclined plate and the other end of the second inclined plate are respectively connected with the two ends of the top plate; the flat side wall of the driving foot and the top plate The upper end surface is firmly connected;

The first piezoelectric driving assembly and the second piezoelectric driving assembly are symmetrically arranged on the first inclined plane and the second inclined plane, wherein the lower ends of the first side plate and the second side plate of the deformation structure of the first piezoelectric driving assembly are vertically connected to the first inclined surface, including the threaded holes on the first inclined surface, as shown in Figure 3; the preloaded bolts of the first piezoelectric driving assembly are threadedly connected to the threaded holes on the first inclined surface, Stretch into the deformation structure of the first piezoelectric drive component to resist the lower end surface of the first piezoelectric drive component pad, causing the arc side walls of the first piezoelectric drive component conduction block and the first piezoelectric drive component deformation structure The lower end faces of the top plate of the second piezoelectric drive assembly are offset; the lower ends of the first side plate and the second side plate of the second piezoelectric driving assembly deformation structure are vertically connected to the second inclined plane, including the threaded hole on the second inclined plane; The preloaded bolts of the two piezoelectric driving components are threadedly connected to the threaded holes on the second inclined surface, and extend into the deformation structure of the second piezoelectric driving component to resist the lower end surface of the backing plate of the second piezoelectric driving component, so that The arcuate side wall of the conductive block of the second piezoelectric drive component offsets the lower end surface of the top plate of the deformation structure member of the second piezoelectric drive component;

The deformation structural member of the first piezoelectric driving assembly, the deformation structural member of the second piezoelectric driving assembly, the conductive block of the first piezoelectric driving assembly, the conductive block of the second piezoelectric driving assembly, and the conductive block of the first piezoelectric driving assembly. The driving foot and the driving foot of the second piezoelectric driving component are on the same plane;

As shown in Figure 5, the housing is hollow and has a first through-slot communicated with the inner cavity on the upper end surface, which is used to include the base, the first piezoelectric driving component, and the second piezoelectric driving component. inside, so that the driving feet of the first piezoelectric driving component and the second piezoelectric driving component extend from the first through slot; the housing and the base are fixedly connected;

As shown in Figure 4, the wheel-type preloading mechanism includes a runner, a runner frame, m preload springs, and m preload bolts, where m is a natural number greater than or equal to 3;

The wheel includes a wheel body and a wheel axle, and the wheel body can freely rotate around the wheel axle;

The runner frame is in the shape of a flat plate, with a second through slot for the runner body to pass through, and m circumferentially provided through slots that match the pre-tightening bolts. hole;

The runner is arranged in the second through groove, and both ends of its wheel shaft are vertically connected to the side walls of the second through groove, so that part of the wheel body is located above the runner frame and part is located below the runner frame. And the wheel body can rotate freely in the second slot;

The upper end surface of the housing is provided with m threaded holes corresponding to the m preload bolts;

The output shaft is a rectangular parallelepiped and is arranged between the runner and the housing;

The m preload springs are placed on the m preload bolts in one-to-one correspondence; the m preload bolts pass through their corresponding through holes on the runner frame and engage with their corresponding threads on the housing. The holes are threadedly connected, and one end of the preload spring on it is against its nut, and one end is against the upper end surface of the runner frame, so that the driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component It offsets the lower end surface of the output shaft, and the upper end surface of the runner and the output shaft between the driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component offset; the runner and the The driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component are on the same plane.

As a further optimization solution of the wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure of the present invention, the output shaft is provided with a friction layer made of ceramic material to improve the friction between the runner and the output shaft. and output shaft wear resistance.

As a further optimization solution of the wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure of the present invention, the deformation structural members of the first and second piezoelectric driving components are made of aluminum alloy, spring steel or brass. made of.

As a further optimization solution of the wheel-type pre-loaded low-frequency piezoelectric actuator based on the flexible hinge structure of the present invention, the driving feet of the first and second piezoelectric driving components are made of alumina ceramic materials or zirconia ceramic materials. In order to increase the friction during friction driving and improve the service life.

In the present invention, when the first piezoelectric driving component and the second piezoelectric driving component are excited by voltage, the driving feet of the first piezoelectric driving component and the second piezoelectric driving component will produce periodic telescopic motion. Between the output shaft and the driving foot, Under the action of the friction force between the output shaft and the output shaft, the output shaft produces periodic motion in different steps. By stimulating the first piezoelectric driving component and the second piezoelectric driving component, the forward or reverse driving mode can be realized.

The driving voltages of the first piezoelectric driving component and the second piezoelectric driving component adopt modulated triangular waves. Under special working conditions, square waves, trapezoidal waves, sine waves and other waveforms can also be selected as replacements.

Driving methods include but are not limited to the following:

As shown in Figure 6, if it is necessary to drive the output shaft to move forward:

If you need to drive the output shaft to move forward:

Step A.1), adjust the first to fourth preload bolts so that the runner applies preload Fn to the output shaft;

Step A.2), use a rising triangular wave to drive the piezoelectric stack of the first piezoelectric driving component for T1 seconds to extend it by L1, and at the same time control the piezoelectric stack of the second piezoelectric driving component to maintain its original length. At this time The output shaft is pushed forward by the first piezoelectric driving component by a distance of x ₁ under the action of static friction, and at the same time, the runner rotates forward through an angle θ1;

Step A.3), use a descending triangular wave drive to drive the piezoelectric stack of the first piezoelectric drive component for T2 seconds, causing it to shrink back to its original length. T2 is smaller than T1, and the output shaft is pressed by the first piezoelectric stack under the action of sliding friction. The electric drive component pulls the distance x ₂ in the opposite direction, and at the same time, the runner reversely rotates through the angle θ2;

Step A.4), repeat steps A.2) to step A.3) to make the output shaft continuously make positive stick-slip steps, and the step length of each cycle is x ₁ - x ₂ ;

If you need to drive the output shaft to move in reverse:

Step B.1), adjust the first to fourth preload bolts so that the runner applies preload Fn to the output shaft;

Step B.2), use a rising triangular wave to drive the piezoelectric stack of the second piezoelectric driving component for T1 seconds to extend it by L1, and at the same time control the piezoelectric stack of the first piezoelectric driving component to maintain its original length. At this time The output shaft is pushed backward by the second piezoelectric driving component by a distance of x ₁ under the action of static friction, and at the same time, the runner reversely rotates through an angle θ1;

Step B.3), use a descending triangular wave to drive the piezoelectric stack of the second piezoelectric drive component for T2 seconds, causing it to shrink back to its original length. T2 is smaller than T1, and the output shaft is driven by the second piezoelectric stack under the action of sliding friction. The driving component pulls the distance x ₂ forward, and at the same time, the runner rotates forward through the angle θ2;

Step B.4), repeat steps B.2) to step B.3), so that the output shaft continuously makes reverse stick-slip steps, and the step length of each cycle is x ₁ - x ₂ .

As shown in Figure 8, the rise and fall time ratio of the triangle wave is generally greater than 7:3, that is, T1:T2 is generally greater than 7:3, and 9:1 is preferred.

It can be understood by one of ordinary skill in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in general dictionaries are to be understood to have meanings consistent with their meaning in the context of the prior art, and are not to be taken in an idealized or overly formal sense unless defined as herein. explain.

The above-mentioned specific embodiments further describe the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (6)

1. A wheel-type preloaded low-frequency piezoelectric actuator based on a flexible hinge structure, which is characterized by including a base, a first piezoelectric driving component, a second piezoelectric driving component, a housing, an output shaft, and a wheel-type actuator. Preload mechanism; The base is provided with symmetrical first bevel and second bevel to form a V-shaped notch, and the first bevel and second bevel are symmetrically provided with threaded through holes perpendicular to the bevel; The first piezoelectric driving component and the second piezoelectric driving component have the same structure, and both include preloaded bolts, gaskets, piezoelectric stacks, conductive blocks, deformation structural members and driving feet, wherein the conductive block, driving foot Each foot is a semi-cylinder, including a first end wall, a second end wall, a curved side wall and a flat side wall; the lower end surface of the piezoelectric stack and the upper end surface of the gasket are firmly connected, and the piezoelectric stack The upper end surface of the stack is fixedly connected to the planar side wall of the conductive block; the deformation structure is in an inverted U shape and includes a top plate, first to second inclined plates, first to second flexible hinges, and first to second flexible hinges. Two side plates, the first side plate and the second side plate are arranged in parallel, and the upper ends of the first side plate and the second side plate respectively pass through the first flexible hinge, the second flexible hinge and one end of the first inclined plate. One end of the second inclined plate is connected correspondingly, and the other end of the first inclined plate and the other end of the second inclined plate are respectively connected with the two ends of the top plate; the flat side wall of the driving foot and the top plate The upper end surface is firmly connected; The first piezoelectric driving assembly and the second piezoelectric driving assembly are symmetrically arranged on the first inclined plane and the second inclined plane, wherein the lower ends of the first side plate and the second side plate of the deformation structure of the first piezoelectric driving assembly are vertically connected to the first inclined surface, including the threaded holes on the first inclined surface; the preloaded bolts of the first piezoelectric driving assembly are threadedly connected to the threaded holes on the first inclined surface, extending into the first piezoelectric The lower end surface of the deformation structural member of the driving assembly resists the backing plate of the first piezoelectric driving assembly, so that the arc side wall of the conductive block of the first piezoelectric driving assembly and the lower end surface of the top plate of the deformation structural member of the first piezoelectric driving assembly offset ; The lower ends of the first side plate and the second side plate of the deformation structure of the second piezoelectric driving assembly are vertically connected to the second inclined plane, including the threaded holes on the second inclined plane; the second piezoelectric driving assembly The preloaded bolt is threadedly connected to the threaded hole on the second inclined surface, extends into the deformation structure of the second piezoelectric drive component, and resists the lower end surface of the second piezoelectric drive component pad, so that the second piezoelectric drive component The curved side wall of the conductive block offsets the lower end surface of the top plate of the deformation structure of the second piezoelectric driving component; The deformation structural member of the first piezoelectric driving assembly, the deformation structural member of the second piezoelectric driving assembly, the conductive block of the first piezoelectric driving assembly, the conductive block of the second piezoelectric driving assembly, and the conductive block of the first piezoelectric driving assembly. The driving foot and the driving foot of the second piezoelectric driving component are on the same plane; The housing is hollow and has a first through-slot communicated with its inner cavity on the upper end surface for containing the base, the first piezoelectric driving component and the second piezoelectric driving component, and allowing the third The driving feet of a piezoelectric driving component and a second piezoelectric driving component extend from the first through slot; the housing and the base are fixedly connected; The wheel-type preloading mechanism includes a runner, a runner frame, m preload springs, and m preload bolts, where m is a natural number greater than or equal to 3; The wheel includes a wheel body and a wheel axle, and the wheel body can freely rotate around the wheel axle; The runner frame is in the shape of a flat plate, with a second through slot for the runner body to pass through, and m circumferentially provided through slots that match the pre-tightening bolts. hole; The runner is arranged in the second through groove, and both ends of its wheel shaft are vertically connected to the side walls of the second through groove, so that part of the wheel body is located above the runner frame and part is located below the runner frame. And the wheel body can rotate freely in the second slot; The upper end surface of the housing is provided with m threaded holes corresponding to the m pre-tightening bolts; The output shaft is a rectangular parallelepiped and is arranged between the runner and the housing; The m preload springs are placed on the m preload bolts in one-to-one correspondence; the m preload bolts pass through their corresponding through holes on the runner frame and engage with their corresponding threads on the housing. The holes are threadedly connected, and one end of the preload spring on it is against its nut, and one end is against the upper end surface of the runner frame, so that the driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component It offsets the lower end surface of the output shaft, and the upper end surface of the runner and the output shaft between the driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component offset; the runner and the The driving foot of the first piezoelectric driving component and the driving foot of the second piezoelectric driving component are on the same plane. 2. The wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure according to claim 1, characterized in that the output shaft is provided with a friction layer made of ceramic material to improve the runner and output The friction between the shafts and the wear resistance of the output shaft. 3. The wheel-type preloaded low-frequency piezoelectric actuator based on a flexible hinge structure according to claim 1, characterized in that the deformation structural members of the first and second piezoelectric drive components are made of aluminum alloy, Made of one of spring steel or brass. 4. The wheel-type preloaded low-frequency piezoelectric actuator based on a flexible hinge structure according to claim 1, characterized in that the driving feet of the first and second piezoelectric driving components are made of alumina ceramic materials. Or made of zirconia ceramic material to increase friction during friction driving and improve service life. 5. The working method of the wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure according to claim 1, characterized in that it includes the following steps: If you need to drive the output shaft to move forward: Step A.1), adjust the first to fourth preload bolts so that the runner applies preload Fn to the output shaft; Step A.2), use a rising triangular wave to drive the piezoelectric stack of the first piezoelectric driving component for T1 seconds to extend it by L1, and at the same time control the piezoelectric stack of the second piezoelectric driving component to maintain its original length. At this time The output shaft is pushed forward by the first piezoelectric driving component by a distance of x ₁ under the action of static friction, and at the same time, the runner rotates forward through an angle θ1; Step A.3), use a descending triangular wave drive to drive the piezoelectric stack of the first piezoelectric drive component for T2 seconds, causing it to shrink back to its original length. T2 is smaller than T1, and the output shaft is pressed by the first piezoelectric stack under the action of sliding friction. The electric drive component pulls the distance x ₂ in the opposite direction, and at the same time, the runner reversely rotates through the angle θ2; Step A.4), repeat steps A.2) to step A.3) to make the output shaft continuously make positive stick-slip steps, and the step length of each cycle is x ₁ - x ₂ ; If you need to drive the output shaft to move in reverse: Step B.1), adjust the first to fourth preload bolts so that the runner applies preload Fn to the output shaft; Step B.2), use a rising triangular wave to drive the piezoelectric stack of the second piezoelectric driving component for T1 seconds to extend it by L1, and at the same time control the piezoelectric stack of the first piezoelectric driving component to maintain its original length. At this time The output shaft is pushed backward by the second piezoelectric driving component by a distance of x ₁ under the action of static friction, and at the same time, the runner reversely rotates through an angle θ1; Step B.3), use a descending triangular wave to drive the piezoelectric stack of the second piezoelectric drive component for T2 seconds, causing it to shrink back to its original length. T2 is smaller than T1, and the output shaft is driven by the second piezoelectric stack under the action of sliding friction. The driving component pulls the distance x ₂ forward, and at the same time, the runner rotates forward through the angle θ2; Step B.4), repeat steps B.2) to step B.3), so that the output shaft continuously makes reverse stick-slip steps, and the step length of each cycle is x ₁ - x ₂ . 6. The working method of the wheel-type preloaded low-frequency piezoelectric actuator based on the flexible hinge structure according to claim 5, characterized in that the T1:T2=9:1.