阅读说明：本技术 基于静摩擦的旋转型压电传动装置及其工作方法 (Rotary piezoelectric transmission device based on static friction and working method thereof ) 是由 原路生 王亮 高禹 金家楣 于 2020-11-11 设计创作，主要内容包括：本发明公开了一种基于静摩擦的旋转型压电传动装置及其工作方法,装置包含壳体、2个旋转轴承、输出轴、2个固定模块和2个驱动模块。固定模块包含8个周向均匀设置在壳体内壁上的固定座,2个固定模块所在平面平行；驱动模块包含8个压电驱动单元；压电驱动单元包含柔性铰链、压电促动器和摩擦块；通过控制压电促动器运动的时序,使摩擦块产生固定步序的周期运动,在摩擦块与输出轴间静摩擦力的作用下使输出轴产生正反、向旋转运动,从而实现装置的正、反向运动工作。本发明可靠性高、输出推力大、精度高,通用性较好,易于推广,具有良好的经济效益。(The invention discloses a static friction-based rotary piezoelectric transmission device and a working method thereof. The fixing modules comprise 8 fixing seats which are uniformly arranged on the inner wall of the shell in the circumferential direction, and the planes of the 2 fixing modules are parallel; the driving module comprises 8 piezoelectric driving units; the piezoelectric driving unit comprises a flexible hinge, a piezoelectric actuator and a friction block; the friction block generates periodic motion with fixed step by controlling the motion time sequence of the piezoelectric actuator, and the output shaft generates positive and negative rotary motion under the action of static friction force between the friction block and the output shaft, so that the positive and negative motion work of the device is realized. The invention has the advantages of high reliability, large output thrust, high precision, better universality, easy popularization and good economic benefit.)

1. The rotary piezoelectric transmission device based on static friction is characterized by comprising a shell, a first rotating bearing, a second rotating bearing, an output shaft, a first fixing module, a second fixing module, a first driving module, a second driving module, a third fixing module, a fourth fixing module and a fourth driving module;

both ends of the output shaft are provided with connecting keys for connecting with the outside;

the shell is a hollow cylinder with two closed ends, and the centers of two end surfaces of the shell are provided with through holes;

the first rotating bearing and the second rotating bearing are respectively and correspondingly arranged in through holes on two end faces of the shell, the outer rings are fixedly connected with the shell, and the inner rings are fixedly connected with the output shaft, so that the output shaft can freely rotate relative to the shell;

the first fixing module and the second fixing module respectively comprise 8 fixing seats which are circumferentially and uniformly arranged on the inner wall of the shell, and the plane of the 8 fixing seats of the first fixing module is parallel to the plane of the 8 fixing seats of the second fixing module;

the first driving module, the second driving module and the third driving module respectively comprise 8 piezoelectric driving units;

the piezoelectric driving unit comprises a flexible hinge, a piezoelectric actuator and a friction block; the friction block comprises a connecting part and a friction part, wherein the friction part is an arc surface matched with the side wall of the output shaft and is used for abutting against the side wall of the output shaft and driving the output shaft to rotate through static friction; one end of the connecting part is connected with the friction part, and the other end of the connecting part is connected with one end of the piezoelectric actuator; the other end of the piezoelectric actuator is connected with one end of the flexible hinge; the flexible hinge is used for bending and steering to ensure that no sliding friction occurs between the friction block and the output shaft;

the 8 piezoelectric driving units of the first driving module are arranged on the 8 fixing seats of the first fixing module in a one-to-one correspondence manner, and the second driving module drives the 8 fixing seatsThe 8 piezoelectric driving units of the module are correspondingly arranged on the 8 fixing seats of the second fixing module one by one; the other end of the flexible hinge of the piezoelectric driving unit is fixedly connected with the corresponding fixing seat, the friction parts of the friction blocks of the piezoelectric driving unit are coaxially arranged with the output shaft, and the distance between the friction parts and the output shaft is a preset first distance threshold valuel ₁；

The piezoelectric driving units in the first driving module and the second driving module are used for applying thrust to the output shaft to enable the output shaft to rotate, wherein the thrust applied by 8 piezoelectric driving units in the first driving module is the same in size and direction, the thrust applied by 8 piezoelectric driving units in the second driving module is the same in size and direction, and the thrust applied by the piezoelectric driving units in the first driving module and the second driving module is the same in size and opposite in direction.

2. A stiction-based rotary piezoelectric actuator as recited in claim 1, further comprising a first mounting base and a second mounting base;

the first mounting base and the second mounting base are symmetrically arranged on two sides of the side wall of the shell and are fixedly connected with the shell;

and the first mounting base and the second mounting base are respectively provided with a mounting hole for fixing the shell with the outside.

3. The method of operating a rotary piezoelectric actuator based on static friction as claimed in claim 1, comprising the steps of:

the method comprises the following steps that 8 piezoelectric driving units in a first driving module are sequentially arranged from a first driving unit to an eighth driving unit in the circumferential direction and used for driving an output shaft to rotate in the forward direction, the first piezoelectric driving unit, the third piezoelectric driving unit, the fifth piezoelectric driving unit and the seventh piezoelectric driving unit are a first driving group, and the second piezoelectric driving unit, the fourth piezoelectric driving unit, the sixth piezoelectric driving unit and the eighth piezoelectric driving unit are a second driving group; the 8 piezoelectric driving units in the second driving module are sequentially arranged as a ninth driving unit to a sixteenth driving unit in the circumferential direction, the ninth piezoelectric driving unit, the eleventh piezoelectric driving unit, the thirteenth piezoelectric driving unit and the fifteenth piezoelectric driving unit are a third driving group, and the tenth piezoelectric driving unit, the twelfth piezoelectric driving unit, the fourteenth piezoelectric driving unit and the sixteenth piezoelectric driving unit are a fourth driving group;

if the output shaft needs to be driven to rotate in the positive direction:

step A.1), driving each piezoelectric driving unit in the first driving group to work to enable the piezoelectric driving unit to axially extend, and enabling a friction part of a friction block of the piezoelectric driving unit to be abutted against an output shaft; each piezoelectric driving unit in the second, third and fourth driving subgroups is driven to work, the friction part of the friction block is ensured to be separated from the output shaft, and the distance between the friction part and the output shaft is ensured to be a preset first distance threshold valuel ₁；

Step A.2), continuously driving each piezoelectric driving unit in the first driving small group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of the friction block of each piezoelectric driving unit in the first driving small group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to positively rotate by a preset angleθ；

Step A.3), driving each piezoelectric driving unit in the second driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step A.4), each piezoelectric driving unit in the first driving small group is driven to work to enable the piezoelectric driving unit to axially shorten, the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step A.5), continuously driving each piezoelectric driving unit in the second driving small group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of the friction block of each piezoelectric driving unit in the second driving small group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to positively rotate by a preset angleθ；

Step A.6), each piezoelectric driving unit in the first driving small group is driven to work to enable the piezoelectric driving unit to axially extend, and a friction part of a friction block of the piezoelectric driving unit is abutted against an output shaft;

step A.7), each piezoelectric driving unit in the second driving subgroup is driven to work to axially shorten, so that the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step A.8), repeatedly executing the steps A.2) to A.7);

if the output shaft needs to be driven to rotate reversely:

step B.1), driving each piezoelectric driving unit in the third driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft; each piezoelectric driving unit in the first, second and fourth driving subgroups is driven to work, the friction part of the friction block is ensured to be separated from the output shaft, and the distance between the friction part and the output shaft is ensured to be a preset first distance threshold valuel ₁；

Step B.2), continuously driving each piezoelectric driving unit in the third driving small group to work to enable each piezoelectric driving unit to axially extend, wherein at the moment, the friction part of each piezoelectric driving unit friction block in the third driving small group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to reversely rotate by a preset angleθ；

Step B.3), driving each piezoelectric driving unit in the fourth driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step B.4), driving each piezoelectric driving unit in the third driving subgroup to work to axially shorten the piezoelectric driving units, enabling the friction parts of the friction blocks to be separated from the output shaft, and enabling the distance between the friction parts and the output shaft to be a preset first distance threshold valuel ₁；

And step B.5), continuously driving each piezoelectric driving unit in the fourth driving group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of each piezoelectric driving unit friction block in the fourth driving group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to reversely rotate by a preset angleθ；

Step B.6), driving each piezoelectric driving unit in the third driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step B.7), each piezoelectric driving unit in the fourth driving subgroup is driven to work to shorten the axial direction, so that the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step B.8), repeat steps b.2) through B.7).

Technical Field

The invention relates to the field of piezoelectric drive, in particular to a rotary piezoelectric transmission device based on static friction and a working method thereof.

Background

The rotary piezoelectric transmission device is an actuator based on piezoelectric effect and ultrasonic vibration, and has the characteristics of high corresponding speed, high precision and the like, so that the rotary piezoelectric transmission device is widely applied to the fields of aerospace, war industry and the like. However, the output torque is limited to be small, so that the output torque can only be used as a rotation source of low load in the using process. Therefore, how to increase the rotation torque of the rotary piezoelectric actuator becomes a major problem for further widening the application range of the piezoelectric actuator and improving the performance of the device.

Disclosure of Invention

The invention aims to solve the technical problem of providing a rotating piezoelectric transmission device based on static friction and a working method thereof aiming at the defects involved in the background technology.

The invention adopts the following technical scheme for solving the technical problems:

a static friction-based rotary piezoelectric transmission device comprises a shell, a first rotary bearing, a second rotary bearing, an output shaft, a first fixed module, a second fixed module, a first driving module, a second driving module, a first rotating bearing, a second rotating bearing, a first fixing module, a second fixing module and a first driving module, wherein the first fixing module, the second fixing module and the first driving module;

both ends of the output shaft are provided with connecting keys for connecting with the outside;

the shell is a hollow cylinder with two closed ends, and the centers of two end surfaces of the shell are provided with through holes;

the first rotating bearing and the second rotating bearing are respectively and correspondingly arranged in through holes on two end faces of the shell, the outer rings are fixedly connected with the shell, and the inner rings are fixedly connected with the output shaft, so that the output shaft can freely rotate relative to the shell;

the first fixing module and the second fixing module respectively comprise 8 fixing seats which are circumferentially and uniformly arranged on the inner wall of the shell, and the plane of the 8 fixing seats of the first fixing module is parallel to the plane of the 8 fixing seats of the second fixing module;

the first driving module, the second driving module and the third driving module respectively comprise 8 piezoelectric driving units;

the piezoelectric driving unit comprises a flexible hinge, a piezoelectric actuator and a friction block; the friction block comprises a connecting part and a friction part, wherein the friction part is an arc surface matched with the side wall of the output shaft and is used for abutting against the side wall of the output shaft and driving the output shaft to rotate through static friction; one end of the connecting part is connected with the friction part, and the other end of the connecting part is connected with one end of the piezoelectric actuator; the other end of the piezoelectric actuator is connected with one end of the flexible hinge; the flexible hinge is used for bending and steering to ensure that no sliding friction occurs between the friction block and the output shaft;

the 8 piezoelectric driving units of the first driving module are correspondingly arranged on the 8 fixing seats of the first fixing module one by one, and the 8 piezoelectric driving units of the second driving module are correspondingly arranged on the 8 fixing seats of the second fixing module one by one; the other end of the flexible hinge of the piezoelectric driving unit is fixedly connected with the corresponding fixing seat, the friction parts of the friction blocks of the piezoelectric driving unit are coaxially arranged with the output shaft, and the distance between the friction parts and the output shaft is a preset first distance threshold valuel ₁；

The piezoelectric driving units in the first driving module and the second driving module are used for applying thrust to the output shaft to enable the output shaft to rotate, wherein the thrust applied by 8 piezoelectric driving units in the first driving module is the same in size and direction, the thrust applied by 8 piezoelectric driving units in the second driving module is the same in size and direction, and the thrust applied by the piezoelectric driving units in the first driving module and the second driving module is the same in size and opposite in direction.

The invention further discloses a static friction-based rotary piezoelectric transmission device, which comprises a first mounting base and a second mounting base;

the first mounting base and the second mounting base are symmetrically arranged on two sides of the side wall of the shell and are fixedly connected with the shell;

and the first mounting base and the second mounting base are respectively provided with a mounting hole for fixing the shell with the outside.

The invention also discloses a working method of the rotary piezoelectric transmission device based on the static friction, which comprises the following steps:

the method comprises the following steps that 8 piezoelectric driving units in a first driving module are sequentially arranged from a first driving unit to an eighth driving unit in the circumferential direction and used for driving an output shaft to rotate in the forward direction, the first piezoelectric driving unit, the third piezoelectric driving unit, the fifth piezoelectric driving unit and the seventh piezoelectric driving unit are a first driving group, and the second piezoelectric driving unit, the fourth piezoelectric driving unit, the sixth piezoelectric driving unit and the eighth piezoelectric driving unit are a second driving group; the 8 piezoelectric driving units in the second driving module are sequentially arranged as a ninth driving unit to a sixteenth driving unit in the circumferential direction, the ninth piezoelectric driving unit, the eleventh piezoelectric driving unit, the thirteenth piezoelectric driving unit and the fifteenth piezoelectric driving unit are a third driving group, and the tenth piezoelectric driving unit, the twelfth piezoelectric driving unit, the fourteenth piezoelectric driving unit and the sixteenth piezoelectric driving unit are a fourth driving group;

if the output shaft needs to be driven to rotate in the positive direction:

step A.1), driving each piezoelectric driving unit in the first driving group to work to enable the piezoelectric driving unit to axially extend, and enabling a friction part of a friction block of the piezoelectric driving unit to be abutted against an output shaft; each piezoelectric driving unit in the second, third and fourth driving subgroups is driven to work, the friction part of the friction block is ensured to be separated from the output shaft, and the distance between the friction part and the output shaft is ensured to be a preset first distance threshold valuel ₁；

Step A.2), continuously driving each piezoelectric driving unit in the first driving small group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of the friction block of each piezoelectric driving unit in the first driving small group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to positively rotate by a preset angleθ；

Step A.3), driving each piezoelectric driving unit in the second driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step A.4), each piezoelectric driving unit in the first driving small group is driven to work to enable the piezoelectric driving unit to axially shorten, the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step A.5), continuously driving each piezoelectric driving unit in the second driving small group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of the friction block of each piezoelectric driving unit in the second driving small group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to positively rotate by a preset angleθ；

Step A.6), each piezoelectric driving unit in the first driving small group is driven to work to enable the piezoelectric driving unit to axially extend, and a friction part of a friction block of the piezoelectric driving unit is abutted against an output shaft;

step A.7), each piezoelectric driving unit in the second driving subgroup is driven to work to axially shorten, so that the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step A.8), repeatedly executing the steps A.2) to A.7);

if the output shaft needs to be driven to rotate reversely:

step B.1), driving each piezoelectric driving unit in the third driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft; each piezoelectric driving unit in the first, second and fourth driving subgroups is driven to work, the friction part of the friction block is ensured to be separated from the output shaft, and the distance between the friction part and the output shaft is ensured to be a preset first distance threshold valuel ₁；

Step B.2), continuously driving each piezoelectric driving unit in the third driving small group to work to enable each piezoelectric driving unit to axially extend, wherein at the moment, the friction part of each piezoelectric driving unit friction block in the third driving small group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to reversely rotate by a preset angleθ；

Step B.3), driving each piezoelectric driving unit in the fourth driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step B.4), driving each piezoelectric driving unit in the third driving subgroup to work to axially shorten the piezoelectric driving units, enabling the friction parts of the friction blocks to be separated from the output shaft, and enabling the distance between the friction parts and the output shaft to be a preset first distance threshold valuel ₁；

And step B.5), continuously driving each piezoelectric driving unit in the fourth driving group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of each piezoelectric driving unit friction block in the fourth driving group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to reversely rotate by a preset angleθ；

Step B.6), driving each piezoelectric driving unit in the third driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step B.7), each piezoelectric driving unit in the fourth driving subgroup is driven to work to shorten the axial direction, so that the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step B.8), repeat steps b.2) through B.7).

Compared with the prior art, the invention adopting the technical scheme has the following technical effects:

1. the invention realizes the purpose of large torque of the device by arranging a plurality of groups of piezoelectric actuators and driving an output shaft to rotate forwards or reversely by virtue of static friction force under the action of huge output force of the piezoelectric actuators;

2. the invention adopts the piezoelectric actuator as the excitation source, so the response speed is high, the precision is high, and the rotating speed can be adjusted by changing the input frequency.

Drawings

FIG. 1 is a schematic external view of the present invention;

FIG. 2 is a schematic cross-sectional view of an axial structure of the present invention;

FIG. 3 is a schematic view of the output shaft of the present invention;

FIG. 4 is a schematic view of the structure of the housing, the first fixing module and the second fixing module;

FIG. 5 is a schematic structural view of a friction block of the piezoelectric driving unit according to the present invention;

FIG. 6 is a schematic structural view of a flexible hinge of the piezoelectric driving unit according to the present invention;

FIG. 7 is a schematic view of the structure of the first driving module, the first fixing module and the housing of the present invention;

FIG. 8 is a schematic view of a structure of the first driving module, the first fixing module, the second driving module, the second fixing module, and the housing of the present invention;

FIG. 9 is a schematic view of the structure of the first driving module, the second driving module, and the output shaft of the present invention;

FIG. 10 is a schematic external view of the housing of the present invention;

fig. 11 is a driving operation diagram of the present invention.

In the figure, 1-output shaft, 2-shell, 3-fixing base of first fixed module, 4-flexible hinge of piezoelectric driving unit in first driving group, 5-piezoelectric actuator of piezoelectric driving unit in first driving group, 6-friction block of piezoelectric driving unit in first driving group, 7-fixing base corresponding to piezoelectric driving unit in second driving group, 8-flexible hinge of piezoelectric driving unit in second driving group, 9-piezoelectric actuator of piezoelectric driving unit in second driving group, 10-friction block of piezoelectric driving unit in second driving group, 11-fixing base of second fixed module, 12-flexible hinge of piezoelectric driving unit in third driving group, 13-piezoelectric actuator of piezoelectric driving unit in third driving group, 14-a friction block of a piezoelectric driving unit in a third driving subgroup, 15-a fixed seat corresponding to the piezoelectric driving unit in a fourth driving subgroup, 16-a flexible hinge of the piezoelectric driving unit in the fourth driving subgroup, 17-a piezoelectric actuator of the piezoelectric driving unit in the fourth driving subgroup, 18-a friction block of the piezoelectric driving unit in the fourth driving subgroup, 19-a first mounting base, 20-a first rotating bearing, 21-a second rotating bearing and 22-a connecting key.

Detailed Description

The technical scheme of the invention is further explained in detail by combining the attached drawings:

the present 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 fig. 1 and 2, the present invention discloses a static friction based rotary piezoelectric actuator, which includes a housing, first to second rotary bearings, an output shaft, first to second fixed modules, and first to second driving modules.

As shown in fig. 3, both ends of the output shaft are provided with connection keys for connecting with the outside.

The shell is a hollow cylinder with two closed ends, and the centers of two end surfaces of the shell are provided with through holes;

the first rotating bearing and the second rotating bearing are respectively and correspondingly arranged in the through holes of the two end faces of the shell, the outer ring is fixedly connected with the shell, and the inner ring is fixedly connected with the output shaft, so that the output shaft can freely rotate relative to the shell.

As shown in fig. 4, the first fixing module and the second fixing module both include 8 fixing seats uniformly circumferentially disposed on the inner wall of the housing, and a plane where the 8 fixing seats of the first fixing module are located is parallel to a plane where the 8 fixing seats of the second fixing module are located.

The first to second driving modules each include 8 piezoelectric driving units.

The piezoelectric driving unit comprises a flexible hinge, a piezoelectric actuator and a friction block; as shown in fig. 5, the friction block includes a connecting portion and a friction portion, wherein the friction portion is an arc surface matched with the side wall of the output shaft, and is used for abutting against the side wall of the output shaft and driving the output shaft to rotate through static friction; one end of the connecting part is connected with the friction part, and the other end of the connecting part is connected with one end of the piezoelectric actuator; the other end of the piezoelectric actuator is connected with one end of the flexible hinge; the flexible hinge is used for bending and steering to ensure that sliding friction does not occur between the friction block and the output shaft, and the structural schematic diagram of the flexible hinge is shown in fig. 6.

As shown in fig. 7 and 8, 8 piezoelectric driving units of the first driving module are correspondingly arranged on 8 fixing seats of the first fixing module one by one, and 8 piezoelectric driving units of the second driving module are correspondingly arranged on 8 fixing seats of the second fixing module one by one; the other end of the flexible hinge of the piezoelectric driving unit is fixedly connected with the corresponding fixing seat, the friction parts of the friction blocks of the piezoelectric driving unit are coaxially arranged with the output shaft, and the distance between the friction parts and the output shaft is a preset first distance threshold valuel ₁。

As shown in fig. 9, the piezoelectric driving units in the first driving module and the second driving module are both configured to apply a thrust to the output shaft so that the output shaft rotates, where the thrust applied by 8 piezoelectric driving units in the first driving module is the same in magnitude and direction, the thrust applied by 8 piezoelectric driving units in the second driving module is the same in magnitude and direction, and the thrust applied by the piezoelectric driving units in the first driving module and the second driving module is the same in magnitude and opposite in direction.

As shown in fig. 10, the present invention may further include a first mounting base and a second mounting base;

the first mounting base and the second mounting base are symmetrically arranged on two sides of the side wall of the shell and are fixedly connected with the shell;

and the first mounting base and the second mounting base are respectively provided with a mounting hole for fixing the shell with the outside.

The invention also discloses a working method of the rotary piezoelectric transmission device based on the static friction, which comprises the following steps:

the method comprises the following steps that 8 piezoelectric driving units in a first driving module are sequentially arranged from a first driving unit to an eighth driving unit in the circumferential direction and used for driving an output shaft to rotate in the forward direction, the first piezoelectric driving unit, the third piezoelectric driving unit, the fifth piezoelectric driving unit and the seventh piezoelectric driving unit are a first driving group, and the second piezoelectric driving unit, the fourth piezoelectric driving unit, the sixth piezoelectric driving unit and the eighth piezoelectric driving unit are a second driving group; the 8 piezoelectric driving units in the second driving module are sequentially arranged as a ninth driving unit to a sixteenth driving unit in the circumferential direction, the ninth piezoelectric driving unit, the eleventh piezoelectric driving unit, the thirteenth piezoelectric driving unit and the fifteenth piezoelectric driving unit are a third driving group, and the tenth piezoelectric driving unit, the twelfth piezoelectric driving unit, the fourteenth piezoelectric driving unit and the sixteenth piezoelectric driving unit are a fourth driving group;

as shown in fig. 11, if it is necessary to drive the output shaft to rotate in the forward direction:

step A.1), driving each piezoelectric driving unit in the first driving group to work to enable the piezoelectric driving unit to axially extend, and enabling a friction part of a friction block of the piezoelectric driving unit to be abutted against an output shaft; each piezoelectric driving unit in the second, third and fourth driving subgroups is driven to work, the friction part of the friction block is ensured to be separated from the output shaft, and the distance between the friction part and the output shaft is ensured to be a preset first distance threshold valuel ₁；

Step A.2), continuously driving each piezoelectric driving unit in the first driving small group to work to enable each piezoelectric driving unit to axially extend, and at the moment, rubbing each piezoelectric driving unit rubbing block in the first driving small groupThe part and the output shaft are kept static under the action of static friction force to drive the output shaft to rotate forward by a preset angleθ；

Step A.3), driving each piezoelectric driving unit in the second driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step A.4), each piezoelectric driving unit in the first driving small group is driven to work to enable the piezoelectric driving unit to axially shorten, the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step A.5), continuously driving each piezoelectric driving unit in the second driving small group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of the friction block of each piezoelectric driving unit in the second driving small group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to positively rotate by a preset angleθ；

Step A.6), each piezoelectric driving unit in the first driving small group is driven to work to enable the piezoelectric driving unit to axially extend, and a friction part of a friction block of the piezoelectric driving unit is abutted against an output shaft;

step A.7), each piezoelectric driving unit in the second driving subgroup is driven to work to axially shorten, so that the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step A.8), repeatedly executing the steps A.2) to A.7);

if the output shaft needs to be driven to rotate reversely:

step B.1), driving each piezoelectric driving unit in the third driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft; each piezoelectric driving unit in the first, second and fourth driving subgroups is driven to work, the friction part of the friction block is ensured to be separated from the output shaft, and the distance between the friction part and the output shaft is ensured to be a preset first distance threshold valuel ₁；

Step B.2) continuously driving each piezoelectric driving unit in the third driving subgroup to work so as to enable each piezoelectric driving unit to extend axially, wherein the friction part and the friction block of each piezoelectric driving unit in the third driving subgroup are connected with the input end of the friction blockThe output shafts are kept static under the action of static friction force to drive the output shafts to rotate reversely by a preset angleθ；

Step B.3), driving each piezoelectric driving unit in the fourth driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step B.4), driving each piezoelectric driving unit in the third driving subgroup to work to axially shorten the piezoelectric driving units, enabling the friction parts of the friction blocks to be separated from the output shaft, and enabling the distance between the friction parts and the output shaft to be a preset first distance threshold valuel ₁；

And step B.5), continuously driving each piezoelectric driving unit in the fourth driving group to work to enable the piezoelectric driving unit to axially extend, wherein at the moment, the friction part of each piezoelectric driving unit friction block in the fourth driving group and the output shaft keep mutually static under the action of static friction force to drive the output shaft to reversely rotate by a preset angleθ；

Step B.6), driving each piezoelectric driving unit in the third driving group to work to enable the piezoelectric driving unit to axially extend, and enabling the friction part of the friction block to be abutted against the output shaft;

step B.7), each piezoelectric driving unit in the fourth driving subgroup is driven to work to shorten the axial direction, so that the friction part of the friction block is separated from the output shaft, and the distance between the friction part and the output shaft is a preset first distance threshold valuel ₁；

Step B.8), repeat steps b.2) through B.7).

It will be understood by those skilled 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 will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.