Optical pointing platform based on three-degree-of-freedom piezoelectric actuator and working method thereof

Abstract

The application discloses an optical pointing platform based on a three-degree-of-freedom piezoelectric actuator and a working method thereof, and the device comprises a piezoelectric vibrator, a rotor, an improved bearing, a shell and an adjusting module, wherein the adjusting module comprises a connecting barrel, an adjusting end cover and a disc spring. The three-degree-of-freedom piezoelectric actuator is directly driven, and the traditional optical pointing platform composed of three single-degree-of-freedom motors in series and parallel is replaced, so that a transmission mechanism and a speed reducer are not needed, the structural complexity of the device is greatly reduced, and the structural function integration design is realized. The application has the advantages of simple structure, high positioning precision, three-degree-of-freedom rotary motion and high-precision positioning, and is more widely applicable and more applicable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of piezoelectric actuators, in particular to an optical pointing platform based on a three-degree-of-freedom piezoelectric actuator and a working method thereof. BACKGROUND

[0002] In the fields of optical pointing and satellite pose adjustment, the existing precise multi-dimensional driving system is mainly driven by multiple single-degree-of-freedom rotary electromagnetic motors, and multi-degree-of-freedom motion is transmitted through transmission mechanisms and reducers. These structures often result in complex structures and accumulated travel errors, making it difficult to further improve the precision. SUMMARY

[0003] The present application aims to solve the defects involved in the background art and provides an optical pointing platform based on a three-degree-of-freedom piezoelectric actuator and a working method thereof.

[0004] To solve the above technical problems, the present application adopts the following technical solutions:

[0005] The optical pointing platform based on a three-degree-of-freedom piezoelectric actuator comprises a piezoelectric vibrator, a rotor, an improved bearing, a shell, and an adjustment module.

[0006] The piezoelectric vibrator comprises a driving prism, a fixed plate, first to fourth columns, and first to eighth piezoelectric ceramic sheets.

[0007] The driving prism is a regular quadrangular prism with a smaller upper base area than a lower base area, and the lower base is provided with a first V-shaped groove and a second V-shaped groove. The first V-shaped groove and the second V-shaped groove are perpendicular to each other at the center of the lower base, dividing the lower base of the driving prism into four identical square shapes.

[0008] The fixed plate is a square.

[0009] The first to fourth columns are structurally identical, with their upper ends respectively and correspondingly fixed to the first to fourth square shapes of the lower base of the driving prism, and their lower ends are all fixed to the fixed plate perpendicularly, so that the axis of the driving prism passes through the center of the fixed plate. The two outer sides of the first to fourth columns are respectively the first to eighth sides in a clockwise direction.

[0010] The first to eighth piezoelectric ceramic sheets are structurally identical and are arranged at the same height on the first to eighth sides, respectively, and are all polarized in the thickness direction with the polarization direction from the outside to the inside.

[0011] The shell is a hollow regular prism or a hollow cylinder, and the center of the upper end face is provided with a first blind hole for cooperating with the radial spherical plain bearing, and the center of the first blind hole is provided with a through hole for the upper base of the driving prism to pass through.

[0012] The piezoelectric vibrator is arranged in the shell, a fixed plate is fixed on the lower end surface of the shell, and the driving prism is coaxial with the shell;

[0013] The improved bearing adopts a deep groove ball bearing without an inner ring or a thrust ball bearing without an inner ring, and comprises an outer ring, a retainer and a plurality of balls.

[0014] The rotor comprises an output platform, a connecting column and a driving spherical segment, wherein the connecting column is in a cylindrical shape, the driving spherical segment is a hollow spherical surface in the shape of a spherical segment, the lower end of the connecting column is fixed to the center of the outer wall of the driving spherical segment, the upper end is fixed to the center of the output platform perpendicularly, and the axis of the connecting column passes through the spherical center of the driving spherical segment; the radius of the bottom surface of the driving spherical segment is greater than the outer diameter of the original inner ring of the improved bearing and less than the inner diameter of the outer ring of the improved bearing.

[0015] The improved bearing is in clearance fit with the first blind hole gap of the upper end surface of the shell, and can slide freely up and down relative to the shell,

[0016] The opening of the driving spherical segment faces downward, the inner wall thereof abuts against the upper end surface of the driving prism, and the outer wall thereof abuts against each ball of the improved bearing; the output platform and the connecting column are located outside the shell.

[0017] The adjusting module comprises a connecting cylinder, an adjusting end cover and a disc spring.

[0018] The connecting cylinder is a hollow cylinder with openings at both ends, is sleeved outside the improved bearing, and is coaxially fixed to the upper end surface of the shell at the lower end; an outer thread is arranged on the outer wall of the connecting cylinder.

[0019] The adjusting end cover is in a cylindrical shape, a threaded blind hole is arranged at the center of the lower end surface of the adjusting end cover and is matched with the thread on the outer wall of the connecting cylinder, and a through hole is arranged at the center of the threaded blind hole and is used for the output shaft of the rotor to extend out.

[0020] The disc spring is arranged between the adjusting end cover and the radial spherical plain bearing, abuts against the outer ring of the improved bearing at one end, and abuts against the bottom surface of the threaded blind hole at the other end.

[0021] The adjusting end cover and the connecting cylinder are threadedly connected, and are used for adjusting the pre-pressure between the driving spherical segment and the driving prism through the disc spring.

[0022] As a further optimization scheme of the optical pointing platform based on the three-degree-of-freedom piezoelectric actuator, the piezoelectric vibrator is made of any one of titanium alloy, aluminum alloy and brass.

[0023] As a further optimization scheme of the optical pointing platform based on the three-degree-of-freedom piezoelectric actuator, the first to eighth piezoelectric ceramic sheets are correspondingly adhered to the first to eighth side walls through epoxy resin glue.

[0024] The application further discloses a working method of the optical pointing platform based on the three-degree-of-freedom piezoelectric actuator.

[0025] The center of gravity of the piezoelectric vibrator is used as the origin of a Cartesian coordinate system, an axis passing through the origin and parallel to the polarization direction of the second piezoelectric ceramic sheet is used as the X axis, and an axis passing through the origin and parallel to the polarization direction of the first piezoelectric ceramic sheet is used as the Y axis, and the axis of the shell is used as the Z axis;

[0026] If the rotor needs to be driven to rotate in the positive direction around the X axis, the first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes of the piezoelectric vibrator, and the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth driving electrodes of the piezoelectric vibrator.

[0027] The first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes of the piezoelectric vibrator, and the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth driving electrodes of the piezoelectric vibrator.

[0028] If the rotor needs to be driven to rotate in the reverse direction around the X axis, the phase of the third excitation signal is reversed.

[0029] If the rotor needs to be driven to rotate in the positive direction around the Y axis, the first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes of the piezoelectric vibrator, and the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth driving electrodes of the piezoelectric vibrator.

[0030] The first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes of the piezoelectric vibrator, and the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth driving electrodes of the piezoelectric vibrator.

[0031] If the rotor needs to be driven to rotate in the reverse direction around the Y axis, the phase of the third excitation signal is reversed.

[0032] If the rotor needs to be driven to rotate in the positive direction around the Z axis, the first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes of the piezoelectric vibrator, and the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth driving electrodes of the piezoelectric vibrator.

[0033] The first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes of the piezoelectric vibrator, and the first, second, third, fourth, fifth, sixth, seventh and eighth electrodes are respectively connected to the first, second, third, fourth, fifth, sixth, seventh and eighth driving electrodes of the piezoelectric vibrator.

[0034] If the rotor needs to be driven to rotate in the reverse direction around the Z axis, the first excitation signal is changed to lag the third excitation signal by π / 2 in the time phase difference.

[0035] Compared with the prior art, the application has the following technical effects:

[0036] 1. The present application utilizes three degrees of freedom piezoelectric actuator direct drive, instead of the traditional optical pointing platform composed of three single degree of freedom motor series, parallel connection, without using transmission mechanism and reducer, greatly reducing the complexity of the structure of the device, realizing the structure function integration design;

[0037] 2. Can directly realize three orthogonal direction rotation drive of optical pointing platform, increase the positioning accuracy of optical pointing platform at the same time, simplify the mechanical system, more widely applicable scene, stronger applicability. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the cross-sectional structure schematic diagram of the present application;

[0039] Figure 2 is the structure schematic diagram of piezoelectric vibrator in the present application;

[0040] Figure 3 is the polarization direction schematic diagram of the first to eighth piezoelectric ceramic sheet in the present application;

[0041] Figure 4 is the structure schematic diagram of rotor in the present application;

[0042] Figure 5 is the comparative schematic diagram of bending vibration mode of piezoelectric vibrator in two phase difference X axis direction of the present application;

[0043] Figure 6 is the comparative schematic diagram of bending vibration mode of piezoelectric vibrator in two phase difference Y axis direction of the present application;

[0044] Figure 7 is the comparative schematic diagram of longitudinal vibration mode of piezoelectric vibrator in two phase difference of the present application;

[0045] Figure 8 is the working state schematic diagram of piezoelectric vibrator when controlling the output platform to rotate around X axis of the present application;

[0046] Figure 9 is the working state schematic diagram of piezoelectric vibrator when controlling the output platform to rotate around Y axis of the present application;

[0047] Figure 10 is the working state schematic diagram of piezoelectric vibrator when controlling the output platform to rotate around Z axis of the present application.

[0048] In the figure, 1-piezoelectric vibrator, 2-rotor, 3-improved bearing, 4-housing, 5-connection cylinder, 6-adjusting end cover, 7-disc spring, 8-driving prism, 9-fixing plate, 10-first stand column, 11-second stand column, 12-first piezoelectric ceramic sheet, 13-second piezoelectric ceramic sheet, 14-third piezoelectric ceramic sheet, 15-driving ball defect, 16-connection column, 17-output platform. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings:

[0050] The present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. On the contrary, these embodiments are provided to make this disclosure thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the accompanying drawings, components are enlarged for clarity.

[0051] It should be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, and / or parts, these elements, components, and / or parts are not limited by these terms. These terms are merely used to distinguish elements, components, and / or parts from each other. Therefore, the first element, component, and / or part discussed below can become the second element, component, or part without departing from the teachings of the present invention.

[0052] like Figure 1 As shown, the present invention discloses an optical pointing platform based on a three-degree-of-freedom piezoelectric actuator, comprising a piezoelectric vibrator, a rotor, an improved bearing, a housing, and an adjustment module;

[0053] like Figure 2 As shown, the piezoelectric vibrator includes a driving prism, a fixing plate, first to fourth columns, and first to eighth piezoelectric ceramic sheets;

[0054] The driving pyramid is a regular quadrangular pyramid, the area of ​​its upper base is smaller than that of its lower base, and the lower base is provided with a first V-shaped groove and a second V-shaped groove; the first V-shaped groove and the second V-shaped groove are perpendicular to each other at the center of the lower base, dividing the lower base of the driving pyramid into first to fourth squares of the same shape;

[0055] The fixing plate is square;

[0056] The first to fourth columns have the same structure, with their upper ends fixedly connected to the first to fourth squares on the lower surface of the driving prism, and their lower ends fixedly connected perpendicularly to the fixing plate, so that the axis of the driving prism passes through the center of the fixing plate; the two outer side surfaces of the first to fourth columns are the first to eighth side surfaces in a clockwise direction.

[0057] The first to eighth piezoelectric ceramic sheets have the same structure and are arranged one by one at the same height on the first to eighth sides. They are all polarized along the thickness direction, and the polarization direction is from outside to inside. Figure 3 As shown;

[0058] The housing is a hollow regular prism or a hollow cylinder, and a first blind hole for cooperating with the centripetal spherical bearing is provided at the center of the upper end face, and a through hole for the bottom surface of the driving prism to pass through is provided at the center of the first blind hole;

[0059] The piezoelectric vibrator is arranged in the shell, the fixing plate is fixed on the lower end surface of the shell, and the driving prism and the shell are coaxial;

[0060] The improved bearing adopts a deep groove ball bearing with the inner ring removed or a thrust ball bearing with the inner ring removed, comprising an outer ring, a retaining frame and a plurality of balls;

[0061] like Figure 4 As shown, the rotor includes an output platform, a connecting post, and a driving spherical segment, wherein the connecting post is cylindrical, and the driving spherical segment is a hollow spherical segment; the lower end of the connecting post is fixedly connected to the center of the outer wall of the driving spherical segment, and the upper end is fixedly connected to the center of the output platform vertically, and the axis of the connecting post passes through the center of the driving spherical segment; the radius of the bottom surface of the driving spherical segment is larger than the outer diameter of the original inner ring of the improved bearing, and smaller than the inner diameter of the outer ring of the improved bearing;

[0062] The outer ring of the improved bearing and the first blind hole on the upper end surface of the housing are clearance-matched and can slide freely up and down relative to the housing.

[0063] The driving spherical segment is open downward, with its inner wall abutting against the upper end surface of the driving prism, and its outer wall abutting against each ball of the improved bearing; the output platform and the connecting column are both located outside the housing;

[0064] The adjustment module includes a connecting tube, an adjustment end cover and a disc spring;

[0065] The connecting tube is a hollow cylinder with two ends open, which is sleeved outside the improved bearing, and the lower end is coaxially fixedly connected to the upper end surface of the housing; the outer wall of the connecting tube is provided with an external thread;

[0066] The regulating end cap is cylindrical, and a threaded blind hole is provided at the center of its lower end surface for matching with the thread on the outer wall of the connecting tube, and a through hole is provided at the center of the threaded blind hole for the rotor output shaft to extend therethrough;

[0067] The disc spring is arranged between the adjustment end cover and the centripetal spherical bearing, with one end abutting against the outer ring of the improved bearing and the other end abutting against the bottom surface of the threaded blind hole;

[0068] The adjusting end cover is threadedly connected to the connecting tube and is used to adjust the preload between the driving spherical segment and the driving prism through the disc spring.

[0069] The piezoelectric vibrator is preferably made of any one of titanium alloy, aluminum alloy and brass.

[0070] The first to eighth piezoelectric ceramic sheets are correspondingly adhered to the first to eighth side walls by epoxy resin glue.

[0071] The application further discloses a working method of the optical pointing platform based on the three-degree-of-freedom piezoelectric actuator.

[0072] The center of gravity of the piezoelectric vibrator is taken as the origin of the Cartesian coordinate system, an axis passing through the origin and parallel to the polarization direction of the second piezoelectric ceramic sheet is taken as the X axis, and an axis passing through the origin and parallel to the polarization direction of the first piezoelectric ceramic sheet is taken as the Y axis.

[0073] If the rotor needs to be driven to rotate in the positive direction around the X axis, the third excitation signal is taken as a positive sine wave signal, the first excitation signal is taken as a sine wave signal with a phase difference of π / 2 with the third excitation signal, and the second excitation signal is taken as a sine wave signal with a phase opposite to that of the first excitation signal.

[0074] The first, second and third piezoelectric ceramic sheets are applied with the first excitation signal, the sixth and seventh piezoelectric ceramic sheets are applied with the second excitation signal, and the first, fourth, fifth and eighth piezoelectric ceramic sheets are applied with the third excitation signal. Figure 5 and Figure 7 The piezoelectric vibrator is simultaneously excited in the longitudinal vibration mode and the X-axis direction bending vibration mode as shown in Figure 8 and

[0075] If the rotor needs to be driven to rotate in the reverse direction around the X axis, the phase of the third excitation signal is simply taken as a negative sine wave signal.

[0076] If the rotor needs to be driven to rotate in the positive direction around the Y axis, the third excitation signal is taken as a positive sine wave signal, the first excitation signal is taken as a sine wave signal with a phase difference of π / 2 with the third excitation signal, and the second excitation signal is taken as a sine wave signal with a phase opposite to that of the first excitation signal.

[0077] The first, second and third piezoelectric ceramic sheets are applied with the first excitation signal, the sixth and seventh piezoelectric ceramic sheets are applied with the second excitation signal, and the first, fourth, fifth and eighth piezoelectric ceramic sheets are applied with the third excitation signal. Figure 6 and Figure 7 The piezoelectric vibrator is simultaneously excited in the longitudinal vibration mode and the X-axis direction bending vibration mode as shown in Figure 9 and

[0078] If the rotor needs to be driven to rotate in the reverse direction around the Y axis, the phase of the third excitation signal is simply taken as a negative sine wave signal.

[0079] If the rotor needs to be driven to rotate in the positive direction around the Z axis, the third excitation signal is taken as a positive sine wave signal, the first excitation signal is taken as a sine wave signal with a phase difference of π / 2 with the third excitation signal, and the second excitation signal is taken as a sine wave signal with a phase opposite to that of the first excitation signal.

[0080] The second and third piezoelectric ceramic pieces are applied with a first excitation signal, the sixth and seventh piezoelectric ceramic pieces are applied with a second excitation signal, the fourth and fifth piezoelectric ceramic pieces are applied with a third excitation signal, and the first and eighth piezoelectric ceramic pieces are applied with a fourth excitation signal; the fourth excitation signal is an alternating harmonic signal with the same frequency and amplitude as the first excitation signal, and the phase of the fourth excitation signal is opposite to that of the third excitation signal; the piezoelectric vibrator is simultaneously excited in the X-axis direction bending vibration mode and the Y-axis direction bending vibration mode, as shown in Figure 5 and Figure 6 The coupling of the two vibration modes forms a micro-elliptical motion perpendicular to the Z-axis on the driving surface of the piezoelectric vibrator, which drives the spherical rotor to rotate around the Z-axis through friction, as shown in Figure 10

[0081] If it is necessary to drive the rotor to rotate reversely around the Z-axis, the first excitation signal can be changed to lag the third excitation signal by π / 2 in time phase difference.

[0082] Those skilled in the art can understand 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 application belongs. It should also be understood that the terms, such as those defined in a general dictionary, should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0083] The above detailed description of the specific embodiments of the present application further illustrates the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.​

Claims

1. An optical pointing platform based on a three-degree-of-freedom piezoelectric actuator, characterized in that, The piezoelectric vibrator, the rotor, the improved bearing, the shell and the adjusting module are included. The piezoelectric vibrator includes a driving prism, a fixed plate, first to fourth columns and first to eighth piezoelectric ceramic sheets. The driving prism is a regular quadrangular prism with a smaller upper base than a lower base, and the lower base is provided with a first V-shaped groove and a second V-shaped groove. The fixed plate is a square. The first to fourth columns are structurally identical, and upper ends of the first to fourth columns are fixedly connected with the first to fourth squares of the lower base of the driving prism respectively, and lower ends of the first to fourth columns are fixedly connected with the fixed plate perpendicularly, so that an axis of the driving prism passes through a center of the fixed plate. The first to eighth piezoelectric ceramic sheets are structurally identical, and are arranged at the same height of the first to eighth sides respectively. The shell is a hollow regular prism or a hollow cylinder, and a first blind hole for cooperating with the angular ball bearing is arranged at a center of an upper end surface of the shell, and a through hole for the upper base of the driving prism is arranged at a center of the first blind hole. The piezoelectric vibrator is arranged in the shell, and the fixed plate is fixed on a lower end surface of the shell, and the driving prism is coaxial with the shell. The improved bearing is a deep groove ball bearing or a thrust ball bearing with an inner ring removed, and includes an outer ring, a retainer and a plurality of balls. The rotor includes an output platform, a connecting column and a driving spherical segment. The connecting column is cylindrical, and the driving spherical segment is a hollow spherical surface in the shape of a spherical segment. The connecting column is fixedly connected with a center of an outer wall of the driving spherical segment at a lower end, and is fixedly connected with a center of the output platform at an upper end perpendicularly, and an axis of the connecting column passes through a spherical center of the driving spherical segment. The bottom surface of the driving spherical segment has a radius greater than an outer diameter of an original inner ring of the improved bearing and less than an inner diameter of the outer ring of the improved bearing. The driving spherical segment is gap-fitted between the outer ring of the improved bearing and the first blind hole of the upper end surface of the shell, and can slide freely up and down relative to the shell. The output platform and the connecting column are located outside the shell. The adjusting module includes a connecting cylinder, an adjusting end cover and a disc spring. The connecting cylinder is a hollow cylinder with open ends, and is sleeved on the improved bearing, and is fixedly connected with the upper end surface of the shell coaxially at a lower end.

2. The optical pointing platform based on three-degree-of-freedom piezoelectric actuator according to claim 1, wherein, The adjusting end cover is cylindrical, and a threaded blind hole for cooperating with a thread on the outer wall of the connecting cylinder is arranged at a center of a lower end surface of the adjusting end cover, and a through hole for the output shaft of the rotor is arranged at a center of the threaded blind hole. The disc spring is arranged between the adjusting end cover and the angular ball bearing, and is abutted against the outer ring of the improved bearing at one end, and is abutted against a bottom surface of the threaded blind hole at the other end. The adjusting end cover is threadedly connected with the connecting cylinder, and is used for adjusting a pre-pressure between the driving spherical segment and the driving prism through the disc spring. The piezoelectric vibrator is made of any one of titanium alloy, aluminum alloy and brass.

3. The optical pointing platform based on three-degree-of-freedom piezoelectric actuator according to claim 1, wherein, The first to eighth piezoelectric ceramic sheets are correspondingly adhered to the first to eighth side walls by epoxy resin glue.

4. The method for operating the three-degree-of-freedom piezoelectric actuator based optical pointing platform according to claim 1, wherein, Comprising the following steps: The center of gravity of the piezoelectric vibrator is taken as the origin of the Cartesian coordinate system, an axis passing through the origin and parallel to the polarization direction of the second piezoelectric ceramic sheet is taken as the X axis, an axis passing through the origin and parallel to the polarization direction of the first piezoelectric ceramic sheet is taken as the Y axis, and the axis of the shell is taken as the Z axis; If the rotor needs to be driven to rotate in the positive direction around the X axis: The first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are correspondingly adhered to the first to eighth side walls by epoxy resin glue. If the rotor needs to be driven to rotate in the positive direction around the Y axis: The first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are correspondingly adhered to the first to eighth side walls by epoxy resin glue. If the rotor needs to be driven to rotate in the positive direction around the Z axis: The first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are correspondingly adhered to the first to eighth side walls by epoxy resin glue. If the rotor needs to be driven to rotate in the positive direction around the Z axis: The first, second, third, fourth, fifth, sixth, seventh and eighth piezoelectric ceramic sheets are correspondingly adhered to the first to eighth side walls by epoxy resin glue. ​

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