Spherical multi-degree-of-freedom piezoelectric actuating mechanism and driving method thereof

Abstract

The invention discloses a spherical multi-degree-of-freedom piezoelectric actuating mechanism and a driving method thereof. The spherical multi-degree-of-freedom piezoelectric actuating mechanism comprises a spherical vibrator, a rotor, a fixed base and a pre-tightening assembly, the vibrator comprises a piezoelectric vibrator base body, a driving foot and a piezoelectric ceramic piece; the rotor is composed of two hemispherical shells, the two hemispherical shells are combined through the pre-tightening assembly to form a spherical structure which wraps the piezoelectric vibrator, and the fixing base fixes the vibrator by clamping the special position of the vibrator and is located on the other side away from the rotor. The vibrator drives the rotor composed of the two hemispherical shells through friction so as to output torque outwards, and the rotation direction can be changed by changing the excitation direction. The mechanism has the advantages of few components, capability of realizing multi-degree-of-freedom movement, compact structure and the like.

Description

Technical Field

[0001] The invention relates to the field of robots, and in particular to a spherical multi-freedom piezoelectric actuating mechanism and a driving method thereof. Background Art

[0002] Traditional multi-DOF actuators mostly use multiple actuators and complex transmission structures to achieve their purpose, which makes such multi-DOF actuators relatively bulky and difficult to miniaturize and highly integrate. Existing technologies cannot meet the requirements of high precision and high integration in the aerospace and robotics fields. Summary of the invention

[0003] Purpose of the invention: The present invention provides a structural design and driving method for a spherical multi-degree-of-freedom piezoelectric actuator, which solves the problems of bulky size, difficulty in miniaturization and high integration.

[0004] Technical solution: The present invention proposes a spherical multi-degree-of-freedom piezoelectric actuating mechanism, comprising a spherical rotor, a piezoelectric vibrator located inside the spherical rotor, and a fixed base connected to the piezoelectric vibrator; the spherical rotor comprises a first hemispherical shell and a second hemispherical shell, the first hemispherical shell and the second hemispherical shell are fixedly connected by a pre-tightening component, the first hemispherical shell and the second hemispherical shell form a hollow spherical shell with a reserved hole below; the piezoelectric vibrator comprises a plurality of vibration rings, a plurality of driving feet and a plurality of piezoelectric ceramic sheets, driving feet are provided on both sides of the diameter of the vibration ring, the vibration ring comprises a first vibration ring, a second vibration ring, and a third vibration ring, the first vibration ring, the second vibration ring, and the third vibration ring are orthogonal to each other, the first vibration ring, the second vibration ring, and the third vibration ring each comprise a first end face, a second end face and an outer side wall, the driving foot is fixedly connected to the outer side wall of the vibration ring, the plurality of ceramic sheets are evenly distributed on the first end face and the second end face of the first vibration ring, the second vibration ring, and the third vibration ring, and the fixed base passes through the reserved hole below the first hemispherical shell and the second hemispherical shell to clamp the vibration ring and fix the piezoelectric vibrator.

[0005] Preferably, the first vibration ring, the second vibration ring and the third vibration ring have the same shape, which are all thin circular rings.

[0006] Preferably, the piezoelectric vibrator is formed by three thin circular vibration rings orthogonally forming a spherical cage shape.

[0007] Preferably, the first vibration ring, the second vibration ring and the third vibration ring further include an inner side wall, and the inner side wall and the outer side wall are in a circular shape and have the same axis.

[0008] Preferably, the fixed base comprises a first fixed arm, a second fixed arm and a base disc; the base disc is provided with a first fixed arm and a second fixed arm, and the first fixed arm and the second fixed arm are clamped on the first end face and the second end face of the vibration ring to fix the vibration ring.

[0009] Preferably, the pre-tightening assembly comprises an adjusting bolt and a pre-tightening spring, the adjusting bolt comprises a nut, a light column and a stud, and the pre-tightening spring is sleeved on the light column.

[0010] Preferably, countersunk holes are provided on the upper wing span and the side wing span of the outer wall of the first hemispherical shell, and threaded holes corresponding to the countersunk holes are provided on the upper wing span and the side wing span of the outer wall of the second hemispherical shell; one end of the preload spring contacts the nut, and the other end contacts the countersunk hole on the first hemispherical shell, and the adjusting bolt passes through the countersunk hole on the first hemispherical shell and is connected to the threaded hole on the second hemispherical shell, and the sides of the first hemispherical shell and the second hemispherical shell are butted against each other through the adjusting bolt and the preload spring.

[0011] Preferably, the piezoelectric ceramic sheets include forty-eight piezoelectric ceramic sheets, and the forty-eight piezoelectric ceramic sheets are all polarized along a thickness direction and have the same polarization direction.

[0012] Preferably, the first vibration ring is intersected by the second vibration ring and the third vibration ring to form four arc segments, and the first piezoelectric ceramic sheet, the second piezoelectric ceramic sheet, the third piezoelectric ceramic sheet, the fourth piezoelectric ceramic sheet, the fifth piezoelectric ceramic sheet, the sixth piezoelectric ceramic sheet, the seventh piezoelectric ceramic sheet and the eighth piezoelectric ceramic sheet are uniformly distributed in sequence on the first end surface of the first vibration ring along the circumference of the first end surface, wherein the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet are located on the first arc segment, the third piezoelectric ceramic sheet and the fourth piezoelectric ceramic sheet are located on the second arc segment, the fifth piezoelectric ceramic sheet and the sixth piezoelectric ceramic sheet are located on the third arc segment, and the seventh piezoelectric ceramic sheet and the eighth piezoelectric ceramic sheet are located on the Located on the fourth arc segment; on the second end surface of the first vibration ring, along the circumference of the second end surface, there are uniformly distributed a ninth piezoelectric ceramic sheet, a tenth piezoelectric ceramic sheet, an eleventh piezoelectric ceramic sheet, a twelfth piezoelectric ceramic sheet, a thirteenth piezoelectric ceramic sheet, a fourteenth piezoelectric ceramic sheet, a fifteenth piezoelectric ceramic sheet and a sixteenth piezoelectric ceramic sheet in sequence, wherein the ninth piezoelectric ceramic sheet and the tenth piezoelectric ceramic sheet are located on the first arc segment, the eleventh piezoelectric ceramic sheet and the twelfth piezoelectric ceramic sheet are located on the second arc segment, the thirteenth piezoelectric ceramic sheet and the fourteenth piezoelectric ceramic sheet are located on the third arc segment, and the fifteenth piezoelectric ceramic sheet and the sixteenth piezoelectric ceramic sheet are located on the fourth arc segment;

[0013] The second vibration ring is intersected by the first vibration ring and the third vibration ring to form four arc segments, and the first end surface of the second vibration ring is uniformly distributed along the circumference of the first end surface with the seventeenth piezoelectric ceramic sheet, the eighteenth piezoelectric ceramic sheet, the nineteenth piezoelectric ceramic sheet, the twentieth piezoelectric ceramic sheet, the twenty-first piezoelectric ceramic sheet, the twenty-second piezoelectric ceramic sheet, the twenty-third piezoelectric ceramic sheet and the twenty-fourth piezoelectric ceramic sheet in sequence, wherein the seventeenth piezoelectric ceramic sheet and the eighteenth piezoelectric ceramic sheet are located on the first arc segment, the nineteenth piezoelectric ceramic sheet and the twentieth piezoelectric ceramic sheet are located on the second arc segment, the twenty-first piezoelectric ceramic sheet and the twenty-second piezoelectric ceramic sheet are located on the third arc segment, and the twenty-third piezoelectric ceramic sheet and the twenty-fourth piezoelectric ceramic sheet are located on the third arc segment. the second end surface of the second vibration ring is uniformly distributed along the circumference of the second end surface with a twenty-fifth piezoelectric ceramic sheet, a twenty-sixth piezoelectric ceramic sheet, a twenty-seventh piezoelectric ceramic sheet, a twenty-eighth piezoelectric ceramic sheet, a twenty-ninth piezoelectric ceramic sheet, a thirtieth piezoelectric ceramic sheet, a thirty-first piezoelectric ceramic sheet and a thirty-second piezoelectric ceramic sheet, wherein the twenty-fifth piezoelectric ceramic sheet and the twenty-sixth piezoelectric ceramic sheet are located on the first arc segment, the twenty-seventh piezoelectric ceramic sheet and the twenty-eighth piezoelectric ceramic sheet are located on the second arc segment, the twenty-ninth piezoelectric ceramic sheet and the thirtieth piezoelectric ceramic sheet are located on the third arc segment, and the thirty-first piezoelectric ceramic sheet and the thirty-second piezoelectric ceramic sheet are located on the fourth arc segment;

[0014] The third vibration ring is formed by the intersection of the first vibration ring and the second vibration ring to form four arc segments, and the thirty-third piezoelectric ceramic piece, the thirty-fourth piezoelectric ceramic piece, the thirty-fifth piezoelectric ceramic piece, the thirty-sixth piezoelectric ceramic piece, the thirty-seventh piezoelectric ceramic piece, the thirty-eighth piezoelectric ceramic piece, the thirty-ninth piezoelectric ceramic piece and the fortieth piezoelectric ceramic piece are uniformly distributed in sequence along the circumference of the first end surface of the third vibration ring, wherein the thirty-third piezoelectric ceramic piece and the thirty-fourth piezoelectric ceramic piece are located on the first arc segment, the thirty-fifth piezoelectric ceramic piece and the thirty-sixth piezoelectric ceramic piece are located on the second arc segment, the thirty-seventh piezoelectric ceramic piece and the thirty-eighth piezoelectric ceramic piece are located on the third arc segment, and the thirty-ninth piezoelectric ceramic piece and the fortieth piezoelectric ceramic piece are located on the fourth arc segment. On the second end face of the third vibration ring, the forty-first piezoelectric ceramic sheet, the forty-second piezoelectric ceramic sheet, the forty-third piezoelectric ceramic sheet, the forty-fourth piezoelectric ceramic sheet, the forty-fifth piezoelectric ceramic sheet, the forty-sixth piezoelectric ceramic sheet, the forty-seventh piezoelectric ceramic sheet and the forty-eighth piezoelectric ceramic sheet are uniformly distributed in sequence along the circumference of the second end face, among which the forty-first piezoelectric ceramic sheet and the forty-second piezoelectric ceramic sheet, wherein the forty-first piezoelectric ceramic sheet and the forty-second piezoelectric ceramic sheet are located on the first arc segment, the forty-third piezoelectric ceramic sheet and the forty-fourth piezoelectric ceramic sheet are located on the second arc segment, the forty-fifth piezoelectric ceramic sheet and the forty-sixth piezoelectric ceramic sheet are located on the third arc segment, and the forty-seventh piezoelectric ceramic sheet and the forty-eighth piezoelectric ceramic sheet are located on the fourth arc segment.

[0015] A driving method for a spherical multi-degree-of-freedom piezoelectric actuator comprises the following steps: applying a first-phase driving voltage to a first piezoelectric ceramic sheet, a second piezoelectric ceramic sheet, a fourth piezoelectric ceramic sheet, a seventh piezoelectric ceramic sheet, an eleventh piezoelectric ceramic sheet, a thirteenth piezoelectric ceramic sheet, a fourteenth piezoelectric ceramic sheet, and a sixteenth piezoelectric ceramic sheet, and applying a second-phase driving voltage to a third piezoelectric ceramic sheet, a fifth piezoelectric ceramic sheet, a sixth piezoelectric ceramic sheet, an eighth piezoelectric ceramic sheet, a ninth piezoelectric ceramic sheet, a tenth piezoelectric ceramic sheet, a twelfth piezoelectric ceramic sheet, and a fifteenth piezoelectric ceramic sheet, so that a spherical rotor generates a rotation in a first direction; applying a first-phase driving voltage to a seventeenth piezoelectric ceramic sheet, an eighteenth piezoelectric ceramic sheet, a twentieth piezoelectric ceramic sheet, a twenty-third piezoelectric ceramic sheet, a twenty-seventh piezoelectric ceramic sheet, a twenty-ninth piezoelectric ceramic sheet, a thirtieth piezoelectric ceramic sheet, and a thirty-second piezoelectric ceramic sheet, and applying a second-phase driving voltage to a third piezoelectric ceramic sheet, a fifth piezoelectric ceramic sheet, a sixth piezoelectric ceramic sheet, an eighth piezoelectric ceramic sheet, a ninth piezoelectric ceramic sheet, a tenth piezoelectric ceramic sheet, a twelfth piezoelectric ceramic sheet, and a fifteenth piezoelectric ceramic sheet, so that a spherical rotor generates a rotation in a first direction; applying a first-phase driving voltage to a seventeenth piezoelectric ceramic sheet, an eighteenth piezoelectric ceramic sheet, a twentieth piezoelectric ceramic sheet, a twenty-third piezoelectric ceramic sheet, a twenty-seventh piezoelectric ceramic sheet, a twenty-ninth piezoelectric ceramic sheet, a The second phase driving voltage is applied to the twenty-first piezoelectric ceramic sheet, the twenty-second piezoelectric ceramic sheet, the twenty-fourth piezoelectric ceramic sheet, the twenty-fifth piezoelectric ceramic sheet, the twenty-sixth piezoelectric ceramic sheet, the twenty-eighth piezoelectric ceramic sheet, and the thirty-first piezoelectric ceramic sheet, so that the spherical rotor rotates in the second direction; the first phase driving voltage is applied to the thirty-third piezoelectric ceramic sheet, the thirty-fourth piezoelectric ceramic sheet, the thirty-sixth piezoelectric ceramic sheet, the thirty-ninth piezoelectric ceramic sheet, the forty-third piezoelectric ceramic sheet, the forty-fifth piezoelectric ceramic sheet, the forty-sixth piezoelectric ceramic sheet, and the forty-eighth piezoelectric ceramic sheet, and the second phase driving voltage is applied to the thirty-fifth piezoelectric ceramic sheet, the thirty-seventh piezoelectric ceramic sheet, the thirty-eighth piezoelectric ceramic sheet, the fortyth piezoelectric ceramic sheet, the forty-first piezoelectric ceramic sheet, the forty-second piezoelectric ceramic sheet, the forty-fourth piezoelectric ceramic sheet, and the forty-seventh piezoelectric ceramic sheet, so that the spherical rotor rotates in the third direction;

[0016] The first-phase driving voltage and the second-phase driving voltage are adjusted so that the phase difference is π / 2, so that the piezoelectric vibrator produces orthogonal radial expansion and contraction vibrations and axial bending vibrations, so that the driving foot end point performs elliptical motion, and the first hemispherical shell and the second hemispherical shell are driven to rotate under the action of friction force; if it is necessary to drive the first hemispherical shell and the second hemispherical shell to rotate in the opposite direction, the first-phase driving voltage and the second-phase driving voltage are adjusted so that the phase difference is -π / 2.

[0017] Beneficial effects: 1. The actuation principle of the actuation mechanism proposed in the present invention is piezoelectric drive technology, and symmetrical multi-leg drive is adopted to improve the continuity of the overall actuation and the motion resolution during actuation;

[0018] 2. The actuating mechanism proposed in the present invention can drive the rotor to rotate in multiple directions using only one piezoelectric vibrator unit. Due to the reduction of the actuating units, the structure of the actuating device is more compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 It is a structural exploded diagram of the present invention;

[0021] Figure 3 It is a schematic diagram of the fixed base structure of the present invention;

[0022] Figure 4 It is a schematic diagram of the structure of the piezoelectric vibrator of the present invention;

[0023] Figure 5 are schematic diagrams of the first to sixteenth piezoelectric ceramic sheets of the present invention;

[0024] Figure 6 are schematic diagrams of the seventeenth to thirty-second piezoelectric ceramic sheets of the present invention;

[0025] Figure 7 are schematic diagrams of the thirty-third to forty-eighth piezoelectric ceramic sheets of the present invention;

[0026] Figure 8 is a schematic diagram of the first hemispherical shell structure of the present invention;

[0027] Fig. 9 This is a schematic structural diagram of the second hemispherical shell of the present invention;

[0028] Fig.10 It is a structural schematic diagram of the adjusting bolt of the present invention;

[0029] Fig.11 is a schematic diagram of the radial vibration mode of the piezoelectric vibrator of the present invention;

[0030] Fig.12 It is a schematic diagram of the axial vibration mode of the piezoelectric vibrator of the present invention. DETAILED DESCRIPTION

[0031] according to Figures 1 to 12 The present invention discloses a spherical multi-degree-of-freedom piezoelectric actuator and a driving method thereof, such as Figure 1 and Figure 2 As shown, the spherical multi-degree-of-freedom piezoelectric actuator includes a piezoelectric vibrator 4, a spherical rotor 1, a preload assembly and a fixed base 2. Figure 4As shown, the piezoelectric vibrator 4 includes a first vibration ring 10, a second vibration ring 11, a third vibration ring 12, a driving foot 13, and first to forty-eight piezoelectric ceramic pieces; the first vibration ring 10, the second vibration ring 11, and the third vibration ring 12 are all thin circular rings with the same shape, and all include a first end face, a second end face, an inner side wall and an outer side wall, and the inner side wall and the outer side wall are both circular and have the same axis; the driving foot 13 is a cylinder, one end of the first and fourth driving feet are fixedly connected to the outer side wall of the first vibration ring, one end of the second and fifth driving feet are fixedly connected to the outer side wall of the second vibration ring, and one end of the third and sixth driving feet are fixedly connected to the outer side wall of the third vibration ring; the first and fourth driving feet are located on both sides of the diameter of the first vibration ring, the second and fifth driving feet are located on both sides of the diameter of the second vibration ring, and the third and sixth driving feet are located on both sides of the diameter of the third vibration ring, and the first to forty-eight piezoelectric ceramic pieces are all polarized along the thickness direction, and the polarization direction is the same.

[0032] The first vibration ring 10 , the second vibration ring 11 and the third vibration ring 12 are orthogonal to each other, and the piezoelectric vibrator 4 is in the shape of a spherical cage composed of three orthogonal thin circular rings.

[0033] like Figure 5 As shown, a first piezoelectric ceramic sheet 14, a second piezoelectric ceramic sheet 15, a third piezoelectric ceramic sheet 16, a fourth piezoelectric ceramic sheet 17, a fifth piezoelectric ceramic sheet 18, a sixth piezoelectric ceramic sheet 19, a seventh piezoelectric ceramic sheet 20 and an eighth piezoelectric ceramic sheet 21 are evenly distributed on a first end surface of the first vibration ring 10, and a ninth piezoelectric ceramic sheet 22, a tenth piezoelectric ceramic sheet 23, an eleventh piezoelectric ceramic sheet 24, a twelfth piezoelectric ceramic sheet 25, a thirteenth piezoelectric ceramic sheet 26, a fourteenth piezoelectric ceramic sheet 27, a fifteenth piezoelectric ceramic sheet 28 and a sixteenth piezoelectric ceramic sheet 29 are evenly distributed on a second end surface of the first vibration ring 10.

[0034] like Figure 6 As shown, the seventeenth piezoelectric ceramic sheet 30, the eighteenth piezoelectric ceramic sheet 31, the nineteenth piezoelectric ceramic sheet 32, the twentieth piezoelectric ceramic sheet 33, the twenty-first piezoelectric ceramic sheet 34, the twenty-second piezoelectric ceramic sheet 35, the twenty-third piezoelectric ceramic sheet 36 and the twenty-fourth piezoelectric ceramic sheet 37 are evenly distributed on the first end surface of the second vibration ring 11, and the twenty-fifth piezoelectric ceramic sheet 38, the twenty-sixth piezoelectric ceramic sheet 39, the twenty-seventh piezoelectric ceramic sheet 40, the twenty-eighth piezoelectric ceramic sheet 41, the twenty-ninth piezoelectric ceramic sheet 42, the thirtieth piezoelectric ceramic sheet 43, the thirty-first piezoelectric ceramic sheet 44 and the thirty-second piezoelectric ceramic sheet 45 are evenly distributed on the second end surface of the second vibration ring 11.

[0035] like Figure 7As shown, the thirty-third piezoelectric ceramic sheet 46, the thirty-fourth piezoelectric ceramic sheet 47, the thirty-fifth piezoelectric ceramic sheet 48, the thirty-sixth piezoelectric ceramic sheet 49, the thirty-seventh piezoelectric ceramic sheet 50, the thirty-eighth piezoelectric ceramic sheet 51, the thirty-ninth piezoelectric ceramic sheet 52 and the fortieth piezoelectric ceramic sheet 53 are evenly distributed on the first end surface of the third vibration ring 12, and the forty-first piezoelectric ceramic sheet 54, the forty-second piezoelectric ceramic sheet 55, the forty-third piezoelectric ceramic sheet 56, the forty-fourth piezoelectric ceramic sheet 57, the forty-fifth piezoelectric ceramic sheet 58, the forty-sixth piezoelectric ceramic sheet 59, the forty-seventh piezoelectric ceramic sheet 60 and the forty-eighth piezoelectric ceramic sheet 61 are evenly distributed on the second end surface of the third vibration ring 12.

[0036] like Figure 8 , Fig. 9 As shown, the spherical rotor 1 is composed of a first hemispherical shell 5 and a second hemispherical shell 3, and the first hemispherical shell 5 and the second hemispherical shell 3 both include an outer wall, an inner wall, a side surface and a lower surface; a hole is left below the hollow spherical shell composed of the first hemispherical shell 5 and the second hemispherical shell 3; the outer wall of the first hemispherical shell 5 is provided with a countersunk hole 62, and the second hemispherical shell 3 is provided with a corresponding threaded hole 63;

[0037] The pre-tightening assembly includes a pre-tightening element corresponding to the countersunk hole 62 provided on the outer wall of the first hemispherical shell and the threaded hole 63 on the outer wall of the second hemispherical shell; the pre-tightening element includes an adjusting bolt 67 and a pre-tightening spring 6, wherein the adjusting bolt 67 includes a nut 66, a light column 65 and a stud 64, the pre-tightening spring 6 is sleeved on the light column 65, one end of the pre-tightening spring 6 is in contact with the nut 66, and the other end is in contact with the countersunk hole 62 on the first hemispherical shell 5; the adjusting bolt 67 passes through the countersunk hole 62 on the first hemispherical shell 5 and is connected to the threaded hole 63 on the second hemispherical shell 3; the sides of the first hemispherical shell 5 and the second hemispherical shell 3 are butted against each other through the adjusting bolt 67 and the pre-tightening spring 6.

[0038] The fixed base 2 includes a first fixed arm 7, a second fixed arm 8 and a base disk 9; the first fixed arm 7 and the second fixed arm 8 are provided on the base disk 9; the first fixed arm 7 and the second fixed arm 8 are clamped on the first and second end faces of the vibration ring of the piezoelectric vibrator 4 to fix the piezoelectric vibrator 4.

[0039] The present invention also discloses a driving method of the spherical multi-degree-of-freedom piezoelectric actuating mechanism, comprising the following steps:

[0040] A first phase driving voltage is applied to the first piezoelectric ceramic sheet 14, the second piezoelectric ceramic sheet 15, the fourth piezoelectric ceramic sheet 17, the seventh piezoelectric ceramic sheet 20, the eleventh piezoelectric ceramic sheet 24, the thirteenth piezoelectric ceramic sheet 26, the fourteenth piezoelectric ceramic sheet 27, and the sixteenth piezoelectric ceramic sheet 29, and a first phase driving voltage is applied to the third piezoelectric ceramic sheet 16, the fifth piezoelectric ceramic sheet 18, the sixth piezoelectric ceramic sheet 19, the eighth piezoelectric ceramic sheet 21, the ninth piezoelectric ceramic sheet 22, the tenth piezoelectric ceramic sheet 23, and the twelfth piezoelectric ceramic sheet The first phase driving voltage is applied to the 17th piezoelectric ceramic piece 30, the 18th piezoelectric ceramic piece 31, the 20th piezoelectric ceramic piece 33, the 23rd piezoelectric ceramic piece 36, the 27th piezoelectric ceramic piece 40, the 29th piezoelectric ceramic piece 42, the 30th piezoelectric ceramic piece 43, and the 32nd piezoelectric ceramic piece 45, so that the spherical rotor 1 rotates in the first direction; the first phase driving voltage is applied to the 19th piezoelectric ceramic piece 32, the 21st piezoelectric ceramic piece 33, the 23rd piezoelectric ceramic piece 36, the 27th piezoelectric ceramic piece 40, the 29th piezoelectric ceramic piece 42, the 30th piezoelectric ceramic piece 43, and the 32nd piezoelectric ceramic piece 45, so that the spherical rotor 1 rotates in the first direction; 4. Apply a second-phase driving voltage to the twenty-second piezoelectric ceramic sheet 35, the twenty-fourth piezoelectric ceramic sheet 37, the twenty-fifth piezoelectric ceramic sheet 38, the twenty-sixth piezoelectric ceramic sheet 39, the twenty-eighth piezoelectric ceramic sheet 41, and the thirty-first piezoelectric ceramic sheet 44, so that the spherical rotor 1 rotates in the second direction; apply a first-phase driving voltage to the thirty-third piezoelectric ceramic sheet 46, the thirty-fourth piezoelectric ceramic sheet 47, the thirty-sixth piezoelectric ceramic sheet 49, the thirty-ninth piezoelectric ceramic sheet 52, the forty-third piezoelectric ceramic sheet 56, the forty-fifth piezoelectric ceramic sheet 58, the forty-sixth piezoelectric ceramic sheet 59, and the forty-eighth piezoelectric ceramic sheet 61; apply a second-phase driving voltage to the thirty-fifth piezoelectric ceramic sheet 48, the thirty-seventh piezoelectric ceramic sheet 50, the thirty-eighth piezoelectric ceramic sheet 51, the fortieth piezoelectric ceramic sheet 53, the forty-first piezoelectric ceramic sheet 54, the forty-second piezoelectric ceramic sheet 55, the forty-fourth piezoelectric ceramic sheet 57, and the forty-seventh piezoelectric ceramic sheet 60, so that the spherical rotor 1 rotates in the third direction;

[0041] The first-phase driving voltage and the second-phase driving voltage are adjusted so that their phase difference is π / 2, so that the piezoelectric vibrator 4 generates orthogonal radial expansion and contraction vibrations and axial bending vibrations, and the end points of the driving foot 13 make elliptical motions, and the first hemispherical shell 5 and the second hemispherical shell 3 are driven to rotate under the action of friction force; if it is necessary to drive the first hemispherical shell 5 and the second hemispherical shell 3 to rotate in the opposite direction, the first-phase driving voltage and the second-phase driving voltage are adjusted so that the phase difference is -π / 2.

Claims

1. A spherical multi-degree-of-freedom piezoelectric actuator, characterized in that: The invention comprises a spherical rotor (1), a piezoelectric vibrator (4) located inside the spherical rotor (1), and a fixed base (2) connected to the piezoelectric vibrator (4); the spherical rotor (1) comprises a first hemispherical shell (5) and a second hemispherical shell (3); the first hemispherical shell (5) and the second hemispherical shell (3) are fixedly connected via a pre-tightening component; the first hemispherical shell (5) and the second hemispherical shell (3) form a hollow spherical shell with a hole reserved at the bottom; the piezoelectric vibrator (4) comprises a plurality of vibration rings, a plurality of driving feet (13) and a plurality of piezoelectric ceramic sheets; the driving feet (13) are provided on both sides of the diameter of the vibration ring; the vibration ring comprises a first vibration ring (10), a second vibration ring (11 ), a third vibration ring (12), the first vibration ring (10), the second vibration ring (11), and the third vibration ring (12) are orthogonal to each other, the first vibration ring (10), the second vibration ring (11), and the third vibration ring (12) each comprise a first end face, a second end face, and an outer side wall, the driving foot (13) is fixedly connected to the outer side wall of the vibration ring, the plurality of ceramic sheets are evenly distributed on the first end face and the second end face of the first vibration ring (10), the second vibration ring (11), and the third vibration ring (12), and the fixed base (2) passes through the reserved holes below the first hemispherical shell (5) and the second hemispherical shell (3) to clamp the vibration ring and fix the piezoelectric vibrator (4).

2. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 1, characterized in that: The first vibration ring (10), the second vibration ring (11) and the third vibration ring (12) have the same shape, all being thin circular rings.

3. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 2, characterized in that: The piezoelectric vibrator (4) is formed into a ball cage shape by orthogonally intersecting three thin circular vibration rings.

4. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 2, characterized in that: The first vibration ring (10), the second vibration ring (11) and the third vibration ring (12) further comprise an inner side wall, wherein the inner side wall and the outer side wall are in a circular ring shape and have the same axis.

5. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 1, characterized in that: The fixed base (2) comprises a first fixed arm (7), a second fixed arm (8) and a base disc (9); the base disc (9) is provided with a first fixed arm (7) and a second fixed arm (8); the first fixed arm (7) and the second fixed arm (8) are clamped on the first end face and the second end face of the vibration ring to fix the vibration ring.

6. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 1, characterized in that: The preload assembly comprises an adjusting bolt (67) and a preload spring (6), wherein the adjusting bolt comprises a nut (66), a light column (65) and a stud (64), and the preload spring (6) is sleeved on the light column (65).

7. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 6, characterized in that: The upper wing span and the side wing span of the outer wall of the first hemispherical shell (5) are provided with countersunk holes (62), and the upper wing span and the side wing span of the outer wall of the second hemispherical shell (3) are provided with threaded holes (63) corresponding to the countersunk holes (62); one end of the preload spring (6) contacts with the nut (66), and the other end contacts with the countersunk hole (62) on the first hemispherical shell (5); the adjusting bolt (67) passes through the countersunk hole (62) on the first hemispherical shell (5) and is connected to the threaded hole (63) on the second hemispherical shell (3); the side surfaces of the first hemispherical shell (5) and the second hemispherical shell (3) are butted against each other through the adjusting bolt (67) and the preload spring (6).

8. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 1, characterized in that: The piezoelectric ceramic sheets include forty-eight piezoelectric ceramic sheets, and the forty-eight piezoelectric ceramic sheets are polarized along the thickness direction and have the same polarization direction.

9. The spherical multi-degree-of-freedom piezoelectric actuator according to claim 8, characterized in that: The first vibration ring (10) is intersected by the second vibration ring (11) and the third vibration ring (12) to form four arc segments. On the first end surface of the first vibration ring (10), a first piezoelectric ceramic sheet (14), a second piezoelectric ceramic sheet (15), a third piezoelectric ceramic sheet (16), a fourth piezoelectric ceramic sheet (17), a fifth piezoelectric ceramic sheet (18), a sixth piezoelectric ceramic sheet (19), a seventh piezoelectric ceramic sheet (20) and an eighth piezoelectric ceramic sheet (21) are uniformly distributed in sequence along the circumference of the first end surface. The first piezoelectric ceramic sheet (14) and the second piezoelectric ceramic sheet (15) are located on the first arc segment, the third piezoelectric ceramic sheet (16) and the fourth piezoelectric ceramic sheet (17) are located on the second arc segment, the fifth piezoelectric ceramic sheet (18) and the sixth piezoelectric ceramic sheet (19) are located on the third arc segment, and the seventh piezoelectric ceramic sheet (20) and the eighth piezoelectric ceramic sheet (21) are uniformly distributed in sequence along the circumference of the first end surface. (21) is located on the fourth arc segment; on the second end surface of the first vibration ring (10), along the circumference of the second end surface, there are uniformly distributed a ninth piezoelectric ceramic sheet (22), a tenth piezoelectric ceramic sheet (23), an eleventh piezoelectric ceramic sheet (24), a twelfth piezoelectric ceramic sheet (25), a thirteenth piezoelectric ceramic sheet (26), a fourteenth piezoelectric ceramic sheet (27), a fifteenth piezoelectric ceramic sheet (28) and a sixteenth piezoelectric ceramic sheet (29), wherein the ninth piezoelectric ceramic sheet (22) and the tenth piezoelectric ceramic sheet (23) are located on the first arc segment, the eleventh piezoelectric ceramic sheet (24) and the twelfth piezoelectric ceramic sheet (25) are located on the second arc segment, the thirteenth piezoelectric ceramic sheet (26) and the fourteenth piezoelectric ceramic sheet (27) are located on the third arc segment, and the fifteenth piezoelectric ceramic sheet (28) and the sixteenth piezoelectric ceramic sheet (29) are located on the fourth arc segment; The second vibration ring (11) is formed by the intersection of the first vibration ring (10) and the third vibration ring (12) to form four arc segments. On the first end surface of the second vibration ring (11), a seventeenth piezoelectric ceramic sheet (30), an eighteenth piezoelectric ceramic sheet (31), a nineteenth piezoelectric ceramic sheet (32), a twentieth piezoelectric ceramic sheet (33), a twenty-first piezoelectric ceramic sheet (34), a twenty-second piezoelectric ceramic sheet (35), a twenty-third piezoelectric ceramic sheet (36) and a twenty-fourth piezoelectric ceramic sheet (37) are uniformly distributed in sequence along the circumference of the first end surface. The seventeenth piezoelectric ceramic sheet (30) and the eighteenth piezoelectric ceramic sheet (31) are located on the first arc segment, the nineteenth piezoelectric ceramic sheet (32) and the twentieth piezoelectric ceramic sheet (33) are located on the second arc segment, the twenty-first piezoelectric ceramic sheet (34) and the twenty-second piezoelectric ceramic sheet (35) are located on the third arc segment, and the twenty-third piezoelectric ceramic sheet (36) and the twenty-fourth piezoelectric ceramic sheet (37) are uniformly distributed in sequence along the circumference of the first end surface. The ceramic sheet (37) is located on the fourth arc segment; on the second end surface of the second vibration ring (11), a twenty-fifth piezoelectric ceramic sheet (38), a twenty-sixth piezoelectric ceramic sheet (39), a twenty-seventh piezoelectric ceramic sheet (40), a twenty-eighth piezoelectric ceramic sheet (41), a twenty-ninth piezoelectric ceramic sheet (42), a thirtieth piezoelectric ceramic sheet (43), a thirty-first piezoelectric ceramic sheet (44) and a thirty-second piezoelectric ceramic sheet (45) are uniformly distributed in sequence along the circumference of the second end surface, wherein the twenty-fifth piezoelectric ceramic sheet (38) and the twenty-sixth piezoelectric ceramic sheet (39) are located on the first arc segment, the twenty-seventh piezoelectric ceramic sheet (40) and the twenty-eighth piezoelectric ceramic sheet (41) are located on the second arc segment, the twenty-ninth piezoelectric ceramic sheet (42) and the thirtieth piezoelectric ceramic sheet (43) are located on the third arc segment, and the thirty-first piezoelectric ceramic sheet (44) and the thirty-second piezoelectric ceramic sheet (45) are located on the fourth arc segment; The third vibration ring (12) is formed by the intersection of the first vibration ring (10) and the second vibration ring (11) to form four arc segments. A thirty-third piezoelectric ceramic sheet (46), a thirty-fourth piezoelectric ceramic sheet (47), a thirty-fifth piezoelectric ceramic sheet (48), a thirty-sixth piezoelectric ceramic sheet (49), a thirty-seventh piezoelectric ceramic sheet (50), a thirty-eighth piezoelectric ceramic sheet (51), a thirty-ninth piezoelectric ceramic sheet (52) and a fortieth piezoelectric ceramic sheet (53) are uniformly distributed in sequence along the circumference of the first end surface of the third vibration ring (12), wherein the thirty-third piezoelectric ceramic sheet (46) and the thirty-fourth piezoelectric ceramic sheet (47) are located on the first arc segment, the thirty-fifth piezoelectric ceramic sheet (48) and the thirty-sixth piezoelectric ceramic sheet (49) are located on the second arc segment, the thirty-seventh piezoelectric ceramic sheet (50) and the thirty-eighth piezoelectric ceramic sheet (51) are located on the third arc segment, and the thirty-ninth piezoelectric ceramic sheet (52) and the fortieth piezoelectric ceramic sheet (53) are located on the fourth arc segment. on a first arc segment; on the second end surface of the third vibration ring (12), along the circumference of the second end surface, there are uniformly distributed a forty-first piezoelectric ceramic sheet (54), a forty-second piezoelectric ceramic sheet (55), a forty-third piezoelectric ceramic sheet (56), a forty-fourth piezoelectric ceramic sheet (57), a forty-fifth piezoelectric ceramic sheet (58), a forty-sixth piezoelectric ceramic sheet (59), a forty-seventh piezoelectric ceramic sheet (60) and a forty-eighth piezoelectric ceramic sheet (61), wherein the forty-first piezoelectric ceramic sheet (54) and the forty-second piezoelectric ceramic sheet (55), wherein the forty-first piezoelectric ceramic sheet (54) and the forty-second piezoelectric ceramic sheet (55) are located on the first arc segment, the forty-third piezoelectric ceramic sheet (56) and the forty-fourth piezoelectric ceramic sheet (57) are located on the second arc segment, the forty-fifth piezoelectric ceramic sheet (58) and the forty-sixth piezoelectric ceramic sheet (59) are located on the third arc segment, and the forty-seventh piezoelectric ceramic sheet (60) and the forty-eighth piezoelectric ceramic sheet (61) are located on the fourth arc segment.

10. A driving method for a spherical multi-degree-of-freedom piezoelectric actuator according to claim 9, characterized in that: The following steps are involved: A first phase driving voltage is applied to the first piezoelectric ceramic sheet (14), the second piezoelectric ceramic sheet (15), the fourth piezoelectric ceramic sheet (17), the seventh piezoelectric ceramic sheet (20), the eleventh piezoelectric ceramic sheet (24), the thirteenth piezoelectric ceramic sheet (26), the fourteenth piezoelectric ceramic sheet (27), and the sixteenth piezoelectric ceramic sheet (29), and a third piezoelectric ceramic sheet (16), the fifth piezoelectric ceramic sheet (18), the sixth piezoelectric ceramic sheet (19), the eighth piezoelectric ceramic sheet (21), the ninth piezoelectric ceramic sheet (22), the tenth piezoelectric ceramic sheet (23), the twelfth piezoelectric ceramic sheet (29) are driven. The first piezoelectric ceramic sheet (25) and the fifteenth piezoelectric ceramic sheet (28) are applied with a second phase driving voltage to make the spherical rotor (1) rotate in a first direction; the first phase driving voltage is applied to the seventeenth piezoelectric ceramic sheet (30), the eighteenth piezoelectric ceramic sheet (31), the twentieth piezoelectric ceramic sheet (33), the twenty-third piezoelectric ceramic sheet (36), the twenty-seventh piezoelectric ceramic sheet (40), the twenty-ninth piezoelectric ceramic sheet (42), the thirtieth piezoelectric ceramic sheet (43), and the thirty-second piezoelectric ceramic sheet (45) to make the nineteenth piezoelectric ceramic sheet (32), the twenty-first piezoelectric ceramic sheet (31), the twentieth piezoelectric ceramic sheet (33), and the twenty-third piezoelectric ceramic sheet (36), and the twenty-seventh piezoelectric ceramic sheet (40), the twenty-ninth piezoelectric ceramic sheet (42), the thirtieth piezoelectric ceramic sheet (43), and the thirty-second piezoelectric ceramic sheet (45) The second phase driving voltage is applied to the piezoelectric ceramic sheet (34), the twenty-second piezoelectric ceramic sheet (35), the twenty-fourth piezoelectric ceramic sheet (37), the twenty-fifth piezoelectric ceramic sheet (38), the twenty-sixth piezoelectric ceramic sheet (39), the twenty-eighth piezoelectric ceramic sheet (41), and the thirty-first piezoelectric ceramic sheet (44), so that the spherical rotor (1) rotates in a second direction; the thirty-third piezoelectric ceramic sheet (46), the thirty-fourth piezoelectric ceramic sheet (47), the thirty-sixth piezoelectric ceramic sheet (49), the thirty-ninth piezoelectric ceramic sheet (52), the forty-third piezoelectric ceramic sheet (56), the A first phase driving voltage is applied to the forty-fifth piezoelectric ceramic sheet (58), the forty-sixth piezoelectric ceramic sheet (59), and the forty-eighth piezoelectric ceramic sheet (61), and a second phase driving voltage is applied to the thirty-fifth piezoelectric ceramic sheet (48), the thirty-seventh piezoelectric ceramic sheet (50), the thirty-eighth piezoelectric ceramic sheet (51), the fortieth piezoelectric ceramic sheet (53), the forty-first piezoelectric ceramic sheet (54), the forty-second piezoelectric ceramic sheet (55), the forty-fourth piezoelectric ceramic sheet (57), and the forty-seventh piezoelectric ceramic sheet (60), so that the spherical rotor (1) generates a rotation in a third direction; The first-phase driving voltage and the second-phase driving voltage are adjusted so that the phase difference is π / 2, so that the piezoelectric vibrator (4) generates orthogonal radial expansion and contraction vibrations and axial bending vibrations, so that the end point of the driving foot (13) performs elliptical motion, and the first hemispherical shell (5) and the second hemispherical shell (3) are driven to rotate under the action of friction force; if it is necessary to drive the first hemispherical shell (5) and the second hemispherical shell (3) to rotate in the opposite direction, the first-phase driving voltage and the second-phase driving voltage are adjusted so that the phase difference is -π / 2.

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