Multi-degree-of-freedom piezoelectric motor stator structure, piezoelectric motor and driving method

Abstract

The invention discloses a multi-degree-of-freedom piezoelectric motor stator structure, a piezoelectric motor and a driving method, and different voltage signals are applied to piezoelectric patches around a stator to excite first-order extension and multi-order bending modal motion, so that a driving foot of the stator generates elliptical motion, and further a mover is pushed to move. Based on the two-degree-of-freedom piezoelectric stator, the two-degree-of-freedom piezoelectric stator is suitable for plane multi-degree-of-freedom driving and rotation multi-degree-of-freedom driving, and the applicable range of the piezoelectric stator is greatly widened; and the two driving modes are simple in structure assembly design, and are suitable for a microminiature multi-degree-of-freedom precision driving system. As the motor can meet the driving requirements of planar and rotary driving occasions, the assembly design requirements of the motor are greatly reduced, and decoupling movement in different directions can be realized; according to the multi-degree-of-freedom driving mode based on the two-degree-of-freedom piezoelectric stator, the design flexibility is high, and the performance of the motor is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and in particular relates to a multi-degree-of-freedom piezoelectric motor stator structure, a piezoelectric motor and a driving method. Background Art

[0002] With the development of science and technology, the demand for high-precision multi-degree-of-freedom motors is increasing in some high-tech fields, such as mobile phone lenses, robots, aerospace, etc. Traditional electromagnetic motors work on the principle of electromagnetic induction. They have complex structures and are susceptible to electromagnetic interference. In addition, due to the volume limitations of magnets and coils, the electromechanical conversion efficiency of electromagnetic motors will decrease significantly as the size decreases. Therefore, it is difficult to achieve miniaturization, high precision and multi-degree-of-freedom motion at the same time.

[0003] Piezoelectric motors use the inverse piezoelectric effect of piezoelectric materials to convert electrical energy into mechanical energy, and then achieve the output of the rotor's macroscopic motion through friction coupling between the stator and the rotor. Therefore, piezoelectric motors have the characteristics of fast response speed, high power density, high displacement resolution, resistance to electromagnetic interference, and the ability to self-lock when power is off. In addition, due to its simple structure, it is easier to achieve multi-axis motion of the motor.

[0004] There are currently two main types of multi-degree-of-freedom drive for piezoelectric motors: one is to use the coordinated cooperation of multiple single-degree-of-freedom motion motors to complete multi-degree-of-freedom motion; the other is to use the coupling between different vibration modes of a single motor stator to achieve multi-degree-of-freedom motion. For the first multi-degree-of-freedom drive method, due to the existence of multiple motor stators and the stators are all single-degree-of-freedom motion, the volume and space required for the multi-degree-of-freedom motion motor are large, and because multiple motors need to be controlled, its multi-degree-of-freedom drive method is complex. For the second multi-degree-of-freedom drive method, due to the multi-mode coupling of a single motor stator, complete decoupling cannot be achieved in the motion in each direction, so its multi-degree-of-freedom drive may be unstable and unable to achieve drive in the corresponding direction. Summary of the invention

[0005] In order to solve the problems existing in the multi-degree-of-freedom drive of the motor, such as complex driving mode, large required volume, instability, etc., the present invention provides a multi-degree-of-freedom piezoelectric motor stator structure, a piezoelectric motor and a driving method, which can be effectively applied to various multi-degree-of-freedom driving occasions, including linear, rotational and other multi-degree-of-freedom motion occasions, and the driving mode is simple, easy to miniaturize, and can realize the decoupling of the multi-degree-of-freedom motor drive in different motion directions.

[0006] A multi-degree-of-freedom piezoelectric motor stator structure includes a plurality of piezoelectric blocks arranged in a circumferential array, wherein the polarization directions of the plurality of piezoelectric blocks are all downward, driving feet are fixed at the ends of the center positions of the plurality of piezoelectric blocks, and the plurality of piezoelectric blocks are respectively connected to an excitation voltage source.

[0007] Preferably, the piezoelectric block is made of high-performance piezoelectric ceramics or single crystal.

[0008] Preferably, the driving foot is in the shape of a hemisphere, a semi-cylinder or a cylinder.

[0009] Preferably, the bottom surface of the piezoelectric block is in the shape of an isosceles right triangle or a fan.

[0010] Preferably, four piezoelectric blocks with isosceles right triangle bottom surfaces are bonded together to form a rectangular structure, and the hemispherical driving feet are bonded to the four ends of the rectangular structure arranged in an array by epoxy resin glue. The polarization directions of the four piezoelectric blocks all point to the center position of the stator, and the two lateral right-angled surfaces of the piezoelectric blocks are grounded, and the other side of the piezoelectric block is connected to the driving signal.

[0011] Preferably, a slider is provided on one side of the driving foot of the multi-degree-of-freedom piezoelectric motor stator structure.

[0012] A piezoelectric motor comprises a micrometer, a bracket, a cross guide rail, a piezoelectric stator and a metal spring. The piezoelectric stator is fixed on the metal spring, and the metal spring is fixed by the bracket. The micrometer is fixed to the upper end of the metal spring by the bracket, and the piezoelectric stator is located at the upper end of the micrometer.

[0013] A piezoelectric motor comprises a spherical rotor, a metal spring, a piezoelectric stator and an annular bracket. The annular bracket is provided with a plurality of mounting holes in a circumferential direction, and a through-hole structure is provided in the middle of the annular bracket. The piezoelectric stator is fixed in the mounting hole of the annular bracket through the metal spring, and the spherical rotor is placed in the through-hole of the annular bracket.

[0014] A piezoelectric motor includes three stators arranged in a circle, with an included angle of 90 degrees between the three stators. The three stators are respectively fixed to a bracket by metal springs, and the middle of the bracket is a through hole; the rotor is installed in the through hole and is located between the three stators, and a ball is arranged on the other side of the rotor where the stator is not arranged.

[0015] A multi-freedom driving method for the above-mentioned piezoelectric motor comprises the following steps:

[0016] Applying excitation voltages with different phase angles to the piezoelectric blocks on the opposite sides of the piezoelectric stator causes the piezoelectric stator to generate first-order extension vibration and first-order bending vibration. The coupling of the two vibration states causes the driving foot of the piezoelectric stator to perform elliptical motion.

[0017] Preferably, the two piezoelectric stators on opposite sides are connected in parallel;

[0018] Preferably, the phase angles of the preset excitation voltages applied by two adjacent piezoelectric blocks differ by ninety degrees.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The present invention provides a multi-degree-of-freedom piezoelectric motor stator structure, including a plurality of piezoelectric blocks arranged in a circumferential array, the polarization directions of the plurality of piezoelectric blocks are all downward, driving feet are fixed at the ends of the central positions of the plurality of piezoelectric blocks, and the plurality of piezoelectric blocks are respectively connected to an excitation voltage source. The stator of the present application can realize two multi-degree-of-freedom motion occasions, linear and rotation, and improves the application occasions of the motor. The driving method is simple, and only 4 voltage signals are required to drive in single motor or multi-motor driving mode, avoiding the problem of requiring multiple voltage signals in multi-motor driving mode, and simplifying the control method.

[0021] Preferably, the driving method is simple, and only 4 voltage signals are required to drive in single-motor or multi-motor driving modes, thereby avoiding the problem of requiring multiple voltage signals in multi-motor driving modes and simplifying the control method;

[0022] This driving method has a simple structural design and does not require a complex mechanical structure, so it is easier to achieve miniaturization.

[0023] The present invention provides a piezoelectric motor, which stimulates multi-order extension and multi-order bending modal motions by applying different voltage signals to the piezoelectric plates around the stator, so that its driving foot generates elliptical motion, thereby driving the mover to move. Based on this dual-degree-of-freedom piezoelectric stator, it is respectively suitable for planar multi-degree-of-freedom drive and rotational multi-degree-of-freedom drive, which greatly improves the applicable scope of the piezoelectric stator; and the structural assembly design of the two driving modes is simple, which is suitable for micro-sized multi-degree-of-freedom precision drive systems. Since it can be applied to the driving requirements of both planar and rotational driving occasions, the assembly design requirements of the motor are greatly reduced, and decoupled motion in different directions can be achieved; the multi-degree-of-freedom drive method based on the dual-degree-of-freedom piezoelectric stator provided by the present invention has high design flexibility and effectively improves the performance of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the stator structure assembly of the multi-degree-of-freedom piezoelectric motor in an embodiment of the present invention.

[0025] Figure 2 This is a diagram of voltage signal applied to the piezoelectric block and a diagram of polarization direction in an embodiment of the present invention.

[0026] Figure 3 Schematic diagram of the motion principle of the dual-degree-of-freedom piezoelectric stator in the embodiment of the present invention; Figure 3 a is the extension mode of the piezoelectric stator, Figure 3 b is the bending mode of the piezoelectric stator, Figure 3 c are two voltage signals applied to the opposite sides of the piezoelectric stator, where the phase difference between the two voltage signals is 90°. Figure 3d is the voltage signal applied to the two groups of piezoelectric ceramic plates on opposite sides when the amplitudes of the two voltage signals on opposite sides of the piezoelectric stator are different.

[0027] Figure 4 is a schematic diagram of the motion mode of the piezoelectric stator in an embodiment of the present invention; Figure 4 a is the first-order extension mode of the dual-freedom stator, Figure 4 b is the first-order bending mode of the stator.

[0028] Figure 5 Schematic diagram of the planar dual-degree-of-freedom driving mode of the piezoelectric stator in an embodiment of the present invention.

[0029] Figure 6 Schematic diagram of the spherical multi-degree-of-freedom driving mode of the piezoelectric stator in an embodiment of the present invention.

[0030] Figure 7 This is a schematic diagram of the structural assembly of a single-stator planar dual-degree-of-freedom piezoelectric motor in Example 1 of the present invention.

[0031] Figure 8 This is a schematic diagram of the structural assembly of a four-stator spherical three-degree-of-freedom piezoelectric motor in Embodiment 2 of the present invention.

[0032] Fig. 9 The structure assembly and cross-sectional view of the three-stator spherical three-degree-of-freedom piezoelectric motor in Embodiment 3 of the present invention are shown in FIG. Fig. 9 (a) is a three-stator spherical three-degree-of-freedom piezoelectric motor structure assembly stereogram. Fig. 9 (b) is a cross-sectional view of the assembly of the three-stator spherical three-degree-of-freedom piezoelectric motor structure. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in a sequence other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] The present invention provides a multi-degree-of-freedom piezoelectric motor stator structure, such as Figure 1 As shown, it includes multiple piezoelectric blocks arranged in a circumferential array, the polarization directions of the multiple piezoelectric blocks are all downward, and a driving foot 105 is fixed to the end of the center position of the multiple piezoelectric blocks. By applying an excitation voltage source to the multiple piezoelectric blocks respectively, the excitation voltage is used to make the stator produce different modes of motion, thereby realizing driving in different directions.

[0036] Specifically, Figure 1 As shown, in one embodiment of the present application, a first piezoelectric block 101, a second piezoelectric block 102, a third piezoelectric block 103 and a fourth piezoelectric block 104 are included, and the first piezoelectric block 101, the second piezoelectric block 102, the third piezoelectric block 103 and the fourth piezoelectric block 104 are arranged in a rectangular array, and a driving foot 105 is fixed to the central end of the array of the first piezoelectric block 101, the second piezoelectric block 102, the third piezoelectric block 103 and the fourth piezoelectric block 104; the first piezoelectric block 101, the second piezoelectric block 102, the third piezoelectric block 103 and the fourth piezoelectric block 104 are all connected to an excitation voltage, so that the first piezoelectric block 101, the second piezoelectric block 102, the third piezoelectric block 103 and the fourth piezoelectric block 104 generate a combined motion, so that the piezoelectric stator generates motions of different modes, driving the driving foot 105 to complete different motion trajectories.

[0037] Specifically, the piezoelectric block is made of high-performance piezoelectric ceramics or single crystals. The driving foot 105 is specifically in the shape of a hemisphere, a semi-cylinder or a cylinder; the driving foot 105 is made of zirconium oxide, aluminum oxide, silicon carbide ceramics, high wear-resistant metal materials or carbon fiber materials.

[0038] The bottom surface of the piezoelectric block is an isosceles right triangle or a fan. In the specific implementation of the present application, four piezoelectric blocks with isosceles right triangle bottom surfaces are bonded together to form a rectangular structure, and the hemispherical driving feet 105 are bonded to the ends of the four rectangular structures arranged in an array by epoxy resin glue, such as Figure 2As shown, the polarization directions of the four piezoelectric blocks all point downward, the upper surfaces of the piezoelectric blocks are connected to the driving signals CH1 (CH2, CH3, CH4), and the lower surfaces of the piezoelectric blocks are grounded.

[0039] The motion mechanism of the above-mentioned multi-degree-of-freedom piezoelectric motor stator structure is explained, such as Figure 3 As shown, taking the X direction as an example, by applying the following to the first piezoelectric block 101 and the second piezoelectric block 103 disposed on opposite sides, Figure 3 C, the first piezoelectric block 101 and the second piezoelectric block 103 will generate Figure 3 The elongation and bending vibrations shown in a and 3b. The phase difference between the two driving voltages is 90°. When the time is from 0 to t1, both piezoelectric signals are positive, and the piezoelectric blocks at both ends of the stator are in the elongation state. At this time, the stator will do elongation motion, such as Figure 3 As shown in a; from time t1 to time t2, since one side of the piezoelectric blocks is in an extended state and the other side is in a shortened state, the stator will produce bending vibration, such as Figure 3 b. Similarly, from time t2 to time t3 and from time t3 to time t4, the piezoelectric stator is in an extended state and a bent state respectively. Similarly, in the Y direction, the piezoelectric stator can also generate this vibration mode.

[0040] On this basis, two sinusoidal voltage signals V0sin(ωt), V0cos(ωt), V1sin(ωt), V1cos(ωt) with a phase difference of 90° are applied to the first piezoelectric block 101, the third piezoelectric block 103, the second piezoelectric block 102, and the fourth piezoelectric block 104 on the opposite sides of the stator, respectively. Figure 3 By changing the amplitudes of V0 and V1, the elongation and bending vibration of the piezoelectric stator in any direction of the XOY plane can be achieved.

[0041] Through finite element simulation software, the size of the piezoelectric stator is optimized so that the frequency difference between its multi-order extension mode (can be first order, second order, third order...) and multi-order bending mode (can be first order, second order, third order...) is less than 1kHz, so as to ensure that it can produce extension and bending motion at the same time. On this basis, the frequencies of the two voltage signals CH1 and CH2 are adjusted to their resonant frequencies and applied to the piezoelectric blocks 101 and 103 respectively. At this time, the piezoelectric stator will produce the following Figure 4 a and Figure 4 b shows the first-order extension vibration and the first-order bending vibration. The coupling of the two vibration states will cause the driving foot 105 of the piezoelectric stator to perform elliptical motion, thereby driving the movement of the rotor.

[0042] Since the piezoelectric stator is symmetrical in the X and Y directions, when the two voltage signals CH1 and CH2 are applied to the first piezoelectric block 101 and the third piezoelectric block 103, the driving foot 105 of the piezoelectric stator performs elliptical motion in the XOZ plane; similarly, when the two voltage signals CH1 and CH2 are applied to the second piezoelectric block 102 and the fourth piezoelectric block 104, the driving foot 105 of the piezoelectric stator performs elliptical motion in the YOZ plane. Therefore, the driving foot 105 of the piezoelectric stator will perform elliptical motion along two different mutually orthogonal directions under different pressurization methods.

[0043] On this basis, two voltage signals V0sin(ωt), V0cos(ωt), V1sin(ωt), V1cos(ωt) with a phase difference of 90° are applied to the first piezoelectric block 101, the third piezoelectric block 103, the second piezoelectric block 102, and the fourth piezoelectric block 104 on the opposite side of the piezoelectric stator. By changing the amplitudes of V0 and V1, the driving foot 105 of the piezoelectric stator can achieve elliptical motion in any direction around the Z axis.

[0044] In one embodiment of the present invention, a multi-degree-of-freedom piezoelectric motor based on the multi-degree-of-freedom piezoelectric motor stator structure includes the multi-degree-of-freedom piezoelectric motor stator structure and a slider 402. On the basis that the driving foot 105 of the piezoelectric stator can make an elliptical motion in any direction around the Z axis, the slider 402 is placed at the piezoelectric stator so that the slider 402 contacts the surface of the driving foot 105. The piezoelectric stator can drive the slider 402 to move in any direction along the XOY plane, such as Figure 5 The slider 402 is a freely movable slider, and the surface of the slider 402 is adhered with wear-resistant materials such as zirconium oxide, aluminum oxide, silicon carbide ceramics, and high wear-resistant metal, and is in direct contact with the driving foot 105. The driving mode is a planar multi-degree-of-freedom driving mode.

[0045] In addition to the planar multi-degree-of-freedom driving mode, the structure of the present application can also realize spherical multi-degree-of-freedom driving, such as Figure 6As shown in the driving schematic diagram. In the driving mode, 501 is a spherical rotor, 502, 503, 504, 505 are all multi-degree-of-freedom piezoelectric motor stator structures, which are placed around the spherical rotor 501. The spherical rotor material is zirconium oxide, aluminum oxide, silicon carbide ceramics, high wear-resistant metal materials or carbon fiber materials. In the dual-stator working mode, the second multi-degree-of-freedom piezoelectric motor stator structure 503 and the fourth multi-degree-of-freedom piezoelectric motor stator structure 505 do not work, the first multi-degree-of-freedom piezoelectric motor stator structure 502 and the third multi-degree-of-freedom piezoelectric motor stator structure 504 move in the positive X direction and the negative X direction respectively, and the spherical rotor 501 will rotate around the Z axis. When the directions of the first multi-degree-of-freedom piezoelectric motor stator structure 502 and the third multi-degree-of-freedom piezoelectric motor stator structure 504 are swapped, the spherical rotor 501 will rotate around the Z axis in the opposite direction; similarly, when the first multi-degree-of-freedom piezoelectric motor stator structure 502 and the third multi-degree-of-freedom piezoelectric motor stator structure 504 do not work, and the second multi-degree-of-freedom piezoelectric motor stator structure 503 and the fourth multi-degree-of-freedom piezoelectric motor stator structure 505 move in the positive Y direction and the negative Y direction respectively, the spherical rotor 501 will rotate around the X axis and can rotate in the opposite direction at the same time. In the four-stator working mode, when the first multi-degree-of-freedom piezoelectric motor stator structure 502 and the third multi-degree-of-freedom piezoelectric motor stator structure 504 move in the positive Z direction and the negative Z direction respectively, the second multi-degree-of-freedom piezoelectric motor stator structure 503 and the fourth multi-degree-of-freedom piezoelectric motor stator structure 505 move in the positive X direction and the negative X direction respectively, the spherical rotor 501 will rotate around the Y axis, and similarly, it can rotate in the opposite direction.

[0046] The above-mentioned multi-degree-of-freedom driving method based on a piezoelectric motor will be described in detail in the following three specific embodiments.

[0047] Example 1

[0048] This embodiment provides a planar dual-degree-of-freedom motor structure based on the piezoelectric stator, such as Figure 7 In the assembly, 601 is a micrometer screw, 602 is a bracket, 603 is a cross rail, 604 is a piezoelectric stator, and 605 is a metal spring, which together form a planar double-degree-of-freedom piezoelectric motor. The piezoelectric stator 604 is fixed on the metal spring 605, and the metal spring 605 is fixed by the bracket. The micrometer screw 601 is fixed to the upper end of the metal spring 605 by the bracket 602, and the piezoelectric stator 604 is located at the upper end of the micrometer screw 601.

[0049] The micrometer screw 601 is used to change the deformation degree of the metal spring 605. By adjusting the length of the micrometer screw, the bending degree of the metal spring is controlled to adjust the preload force of the motor. The bracket 602 is made of aluminum alloy and serves as the overall support structure of the motor. The cross rail 603 is attached with a wear-resistant material on the surface. The wear-resistant material can be zirconium oxide, aluminum oxide, silicon carbide ceramics, high wear-resistant metal materials or carbon fiber materials, which are mainly used to realize the movement of the motor in the X and Y directions. The piezoelectric stator 604 is the multi-degree-of-freedom piezoelectric motor stator structure mentioned above. The metal spring is made of materials such as stainless steel 304 or phosphor bronze, and is mainly used to apply preload force to the piezoelectric stator.

[0050] The overall structure of the motor is connected through a bracket 602, and the deformation of the metal spring 605 is changed by a screw micrometer 601 to adjust the preload between the piezoelectric stator 604 and the cross guide rail 603. By applying two sinusoidal voltage signals CH1 and CH2 with a phase difference of 90° to the piezoelectric stator 604, the driving foot of the piezoelectric stator makes an elliptical motion, thereby pushing the cross slider to move in the X or Y direction. On this basis, by applying two sinusoidal voltage signals CH1 and CH2 with a phase difference of 90° to the two groups of piezoelectric ceramics on the opposite side of the piezoelectric stator 604, the cross slider can be pushed to move in any direction of the XOY plane. This driving method realizes the mutual decoupling of the piezoelectric motor moving in different directions.

[0051] Example 2

[0052] This embodiment provides a rotational three-degree-of-freedom motor structure based on the piezoelectric stator, such as Figure 8 As shown. The rotary three-degree-of-freedom motor includes a spherical rotor 701, a metal spring 702, a piezoelectric stator 703 and an annular bracket 706. The annular bracket 706 has multiple mounting holes in the circumference, and the middle of the annular bracket 706 is a through-hole structure. The piezoelectric stator 703 is fixed in the mounting hole of the annular bracket 706 through the metal spring 702, and the spherical rotor 701 is placed in the through-hole of the annular bracket 706; wherein, the surface of the spherical rotor 701 is made of zirconium oxide, aluminum oxide, silicon carbide ceramics, high wear-resistant metal materials or carbon fiber and other wear-resistant materials, and the surface is polished. The metal springs 702 / 704 are made of phosphor bronze or stainless steel, and have small holes at the ends, which are convenient for screwing into the annular bracket 706. The piezoelectric stator 703 / 705 is bonded to the surface of the metal spring by epoxy resin glue; the annular bracket 706 is made of aluminum alloy, stainless steel and other materials, and the internal connection is polished.

[0053] The overall assembly of the rotary three-degree-of-freedom motor is as follows Figure 8As shown, the spherical rotor 701 is nested in the annular bracket 706, and the contact surface between the two is very small, which can be approximated as linear friction. Four grooves are distributed around the overall bracket, and the corresponding four piezoelectric stators are placed in them respectively, and the stators are fixed in them with screws through the small holes of the metal springs. The two piezoelectric stators on the opposite sides are connected in parallel, and the pitch motion of the internal spherical rotor can be realized by applying the two voltage signals CH1 and CH2 to the two parallel piezoelectric stators. The specific principle is described in the above specification. Similarly, all four piezoelectric stators are connected in parallel, and the two voltage signals CH1 and CH2 are applied to the four parallel piezoelectric stators to realize the roll motion of the spherical rotor. The pitch motion along the X-axis and Y-axis and the roll motion along the Z-axis together constitute the three-degree-of-freedom motion of the rotary motor. Through three different motor combinations, the decoupling of the rotor in different motion directions is achieved.

[0054] Example 3

[0055] This embodiment provides a ball-based rotating three-degree-of-freedom motor structure, such as Fig. 9 The rotary three-degree-of-freedom motor includes three stators 802, 804, and 806 arranged on three circumferences, with an angle of 90 degrees between the three stators. The stators 802, 804, and 806 are fixed to a bracket 809 through metal springs 801, 803, and 805, respectively. A rotor 807 is installed between the stators 802, 804, and 806. A ball 808 is arranged on the other side of the rotor 807 where the stator is not arranged. The metal springs 801, 803, and 805 are made of phosphor bronze or stainless steel and have good elasticity. They are embedded in the bracket 809 through screws. 9; the piezoelectric stators 802, 804, 806 are the piezoelectric stators mentioned above, which are bonded to the surface of the metal spring by epoxy resin glue; the spherical rotor 807 is made of wear-resistant materials such as zirconium oxide, aluminum oxide, silicon carbide ceramics, high wear-resistant metal materials or carbon fiber, and is surface-polished; the ball 808 is made of wear-resistant materials such as zirconium oxide, aluminum oxide, silicon carbide ceramics, high wear-resistant metal materials or carbon fiber, and has good wear resistance; the integral bracket 809 is made of aluminum alloy, stainless steel and other materials, and the internal joints are polished and oxidized.

[0056] The overall assembly of the rotary three-degree-of-freedom motor is as follows Fig. 9 As shown in (a) in FIG. 8 . The spherical rotor 807 is nested in the integral bracket 809. In order to reduce the friction between the spherical rotor 807 and the bracket 809, a certain gap is left between the rotor 807 and the bracket 809, and a groove is opened inside the bracket 809, and the ball 808 is filled into the groove, as shown in FIG. Fig. 9As shown in (b) in the figure. Among them, rolling friction is formed between the ball 808 and the spherical rotor 807, which greatly reduces the friction force. Three grooves are distributed on the upper, left and right sides of the overall bracket, and the corresponding three piezoelectric stators 802, 804, and 806 are placed therein respectively, and the stators are fixed therein with screws through the small holes of the metal springs. When the sinusoidal signals CH1 and CH2 are applied to the stator 802, the spherical rotor can rotate around the X-axis; when the two-way sinusoidal signals CH1 and CH2 are applied to the stators 804 and 806 on the left and right sides, the spherical rotor 807 rotates around the Z-axis; when the three-way sinusoidal signals CH1 and CH2 are applied to the stators 802, 804 and 806 respectively, the spherical rotor rotates around the y-axis. The rotational motion around the X-axis, Y-axis and Z-axis together constitutes the three-degree-of-freedom motion of the rotary motor. At the same time, the three different motor combinations realize the decoupling of the rotor in different motion directions.

[0057] From the above, it can be seen that the multi-degree-of-freedom driving method based on the dual-degree-of-freedom piezoelectric stator proposed in the present invention can be applied to different multi-degree-of-freedom driving occasions, including planar multi-degree-of-freedom driving and rotational multi-degree-of-freedom driving. Compared with the traditional multi-degree-of-freedom driving method, it has the advantages of simple structure, easy miniaturization and integration, power-off self-locking, and applicability to different multi-degree-of-freedom driving occasions. It solves the problems of complex structure, large required volume, instability, etc. in multi-degree-of-freedom driving, and brings new solutions to micro-precision multi-degree-of-freedom driving systems.

[0058] Finally, it should be noted that the above embodiments are only intended to illustrate the technical concept of the present invention in detail, rather than to limit it. Those skilled in the art can understand that: without departing from the spirit and scope of the present invention and the appended claims, various changes, modifications and substitutions are possible, which all belong to the protection scope of this application, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A multi-degree-of-freedom piezoelectric motor stator structure, characterized in that: It comprises a plurality of piezoelectric blocks arranged in a circumferential array, wherein the polarization directions of the plurality of piezoelectric blocks all point to the center position of the array, a driving foot (105) is fixed at the center position end of the plurality of piezoelectric blocks, and the plurality of piezoelectric blocks are respectively connected to an excitation voltage source.

2. The multi-degree-of-freedom piezoelectric motor stator structure according to claim 1, characterized in that: The piezoelectric block is made of high-performance piezoelectric ceramics or single crystal.

3. The multi-degree-of-freedom piezoelectric motor stator structure according to claim 1, characterized in that: The driving foot (105) is in the shape of a hemisphere, a semi-cylinder or a cylinder.

4. The multi-degree-of-freedom piezoelectric motor stator structure according to claim 1, characterized in that: The bottom surface of the piezoelectric block is in the shape of an isosceles right triangle or a fan.

5. The multi-degree-of-freedom piezoelectric motor stator structure according to claim 1, characterized in that: Four piezoelectric blocks with isosceles right triangle bottom surfaces are bonded together to form a rectangular structure, and a hemispherical driving foot (105) is bonded to the ends of the four rectangular structures arranged in an array by epoxy resin glue. The polarization directions of the four piezoelectric blocks are all downward, the lower surfaces of the piezoelectric blocks are all grounded, and the upper surfaces of the four piezoelectric blocks are respectively connected to sinusoidal voltage signals with phase differences.

6. A piezoelectric motor based on the multi-degree-of-freedom piezoelectric motor stator structure according to claim 1, characterized in that: A slider is provided on one side of the driving foot of the multi-degree-of-freedom piezoelectric motor stator structure.

7. A single-stator linear dual-degree-of-freedom piezoelectric motor based on the multi-degree-of-freedom piezoelectric motor stator structure of claim 1, characterized in that: The invention comprises a micrometer screw (601), a bracket (602), a cross guide rail (603), a piezoelectric stator (604) and a metal spring (605), wherein the piezoelectric stator (604) is fixed on the metal spring (605), the metal spring (605) is fixed by the bracket, the micrometer screw (601) is fixed to the upper end of the metal spring (605) by the bracket (602), and the piezoelectric stator (604) is located at the upper end of the micrometer screw (601).

8. A four-stator spherical three-degree-of-freedom piezoelectric motor based on the multi-degree-of-freedom piezoelectric motor stator structure of claim 1, characterized in that: The invention comprises a spherical rotor (701), a metal spring (702), a piezoelectric stator (703) and an annular bracket (706). The annular bracket (706) is provided with a plurality of mounting holes in a circumferential direction. The middle of the annular bracket (706) is a through-hole structure. The piezoelectric stator (703) is fixed in the mounting hole of the annular bracket (706) through the metal spring (702). The spherical rotor (701) is placed in the through-hole of the annular bracket (706).

9. A three-stator spherical multi-degree-of-freedom piezoelectric motor based on the multi-degree-of-freedom piezoelectric motor stator structure of claim 1, characterized in that: It includes three stators arranged in a circle, with an included angle of 90 degrees between the three stators. The three stators are fixed to a bracket by metal springs respectively, and there is a through hole in the middle of the bracket; the rotor is installed in the through hole and is located between the three stators, and a ball is arranged on the other side of the rotor where the stator is not arranged.

10. A multi-freedom driving method for a piezoelectric motor according to any one of claims 7 to 9, characterized in that: The following steps are involved: Applying excitation voltages with different phase angles to the piezoelectric blocks on the opposite sides of the piezoelectric stator causes the piezoelectric stator to generate extension vibration and bending vibration. The coupling of the two vibration states causes the driving foot of the piezoelectric stator to perform elliptical motion.

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