Friction differential type two-degree-of-freedom bionic stepping piezoelectric actuator

Abstract

The invention discloses a friction differential type two-degree-of-freedom bionic stepping piezoelectric actuator, which belongs to the technical field of precision driving and comprises a driving mechanism A, a driving mechanism B, a fixed support and an output shaft. The fixing support comprises a supporting frame and two fixing feet, the two fixing feet are symmetrically connected to the two sides of the supporting frame, and a hole III is formed in the center of the supporting frame; the driving mechanism B comprises four pairs of piezoelectric wafers, a linear driving mechanism and a rotary driving mechanism; the driving mechanism A and the driving mechanism B can sequentially complete displacement along the X axis or rotation around the X axis and intervention of a fixed support, so that the driving mechanism A and the driving mechanism B can drive the output shaft to move or rotate and then return to the initial state one by one without influencing the output shaft, and the process is continuously and circularly repeated. According to the linear-rotation two-degree-of-freedom integrated cross-scale motion mechanism, a linear driving mechanism and a rotation driving mechanism are ingeniously combined, and the linear-rotation two-degree-of-freedom integrated cross-scale motion is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of precision driving, and in particular relates to a friction differential two-degree-of-freedom bionic stepping piezoelectric actuator. Background Art

[0002] Precision drive refers to highly accurate and controllable movement at the micron or even nanometer scale. This technology usually relies on various sensors and control systems to achieve precise positioning and motion control. With the development of precision drive application fields, various high-end technology fields such as medical equipment and aerospace have put forward higher requirements for precision drive. Precision drive technology mainly includes traditional servo motor drive, hydraulic and pneumatic drive, and piezoelectric drive. Piezoelectric drive has become a hot research direction in the field of precision drive due to its high resolution, no electromagnetic interference and fast response speed. Among them, piezoelectric stepper actuators based on the stepping principle are mainly divided into inchworm piezoelectric actuators, seal piezoelectric actuators and inertial piezoelectric actuators according to different structural compositions and driving principles.

[0003] The existing seal-type piezoelectric stepping actuator is mainly composed of a feed unit, a continuous clamping unit and an intermittent clamping unit. The design of the intermittent clamping unit causes the seal-type piezoelectric stepping actuator to have a large parasitic displacement and a single degree of freedom, which is not conducive to high-resolution multi-degree-of-freedom motion.

[0004] The present invention is based on the differential principle, cancels the clamping action of the existing seal-type piezoelectric stepping actuator, eliminates parasitic displacement, and realizes integrated cross-scale stepping motion with two degrees of freedom, linear and rotation, through a compact structural design. Summary of the invention

[0005] The invention aims to solve the problems of single degree of freedom and large parasitic displacement of the existing seal-type piezoelectric stepping actuator, and proposes a friction differential two-degree-of-freedom bionic stepping piezoelectric actuator.

[0006] A friction differential two-degree-of-freedom bionic stepping piezoelectric actuator, comprising a driving mechanism A, a driving mechanism B, a fixed support and an output shaft; The fixed support comprises a support frame and two fixed feet, the two fixed feet are symmetrically connected to both sides of the support frame, and a hole III is provided in the center of the support frame; The driving mechanism B includes four pairs of piezoelectric chips, a linear driving mechanism and a rotary driving mechanism; The linear drive mechanism includes two output ends I, two driving hinges I and a fixed end I, one end of the two driving hinges I is fixedly connected to one output end I respectively, the other ends of the two driving hinges I are fixedly connected to the fixed end I, and a hole I is opened in the center of the fixed end I; The rotary drive mechanism includes two fixed ends II, two driving hinges II and an output end II, one end of the two driving hinges II is fixedly connected to a fixed end II respectively, the other ends of the two driving hinges II are fixedly connected to the output end II, and a hole II is opened in the center of the output end II; Four pairs of piezoelectric chips are respectively connected to both sides of two driving hinges I and two driving hinges II; The drive mechanism A and the drive mechanism B have the same structural configuration and are symmetrically installed on both sides of the fixed support; The output shaft passes through hole II, hole I and hole III in sequence and is in frictional contact with holes II and III; Driving mechanism A and driving mechanism B can complete displacement along the X-axis or rotation around the X-axis in a timely manner. The intervention of fixed support enables driving mechanism A and driving mechanism B to drive the output shaft to produce displacement or rotation, and then retreat to the initial state one by one without affecting the output shaft. The process is repeated continuously, and the output shaft can realize cross-scale stepping linear motion or stepping rotational motion.

[0007] Preferably, four fastening threaded holes I are evenly distributed around the support frame, and each fixing foot is provided with a fixing hole for fixing the entire actuator to the working plane; Four countersunk holes I corresponding to the fastening threaded holes I are evenly distributed around the fixed end I, and four fastening bolts pass through the countersunk holes I respectively and are installed in the fastening threaded holes I, so as to fix the linear drive mechanism to the fixed support; two fastening threaded holes II are processed on both output ends I; The two fixed ends II are processed with two countersunk holes II corresponding to the fastening threaded holes II. Four fastening bolts II pass through the countersunk holes II respectively and are installed in the fastening threaded holes II, thereby fixedly connecting the rotary drive mechanism and the linear drive mechanism.

[0008] Preferably, two ball-end screw holes I are provided at the center of the top and bottom of the support frame; the two ball-end screws I are respectively installed in the ball-end screw holes I at the top and bottom of the fixed support and are in friction contact with the output shaft, and the ball-end screws I are used to adjust the friction preload between the fixed support and the output shaft.

[0009] Preferably, two ball-end screw holes II are provided at the top and bottom centers of the output end II, and four ball-end screws II are respectively installed in the ball-end screw holes II at the top and bottom of the rotary drive mechanism and are in frictional contact with the output shaft. The ball-end screws II are used to adjust the friction preload between the rotary drive mechanism and the output shaft.

[0010] Preferably, the linear drive mechanism and the rotary drive mechanism are both integrally machined from a single piece of elastic metal material.

[0011] Beneficial effects of the present invention: Through two symmetrically arranged drive mechanisms and a fixed support, a friction force / torque difference is generated, thereby realizing the stepping linear / rotational motion of the output shaft using the differential principle. This design eliminates the parasitic displacement generated by the clamping motion of the existing seal-type piezoelectric stepping actuator, and through a compact structural design, the linear drive mechanism and the rotary drive mechanism are cleverly combined to achieve integrated cross-scale motion with two degrees of freedom: linear and rotation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention; Figure 2 It is an exploded schematic diagram of the driving mechanism of the present invention; Figure 3 It is a three-dimensional structural schematic diagram of a linear drive mechanism; Figure 4 is a schematic diagram of the three-dimensional structure of the rotary drive mechanism; Figure 5 A schematic diagram of a three-dimensional structure of a fixed support; Figure 6 This is a fluctuation diagram of the voltage signal of the piezoelectric chip control of the present invention; Figure 7 This is a schematic diagram of the linear motion principle of the present invention under control voltage drive; Figure 8 This is a schematic diagram of the rotational motion principle of the present invention driven by a control voltage.

[0013] Among them, the reference numerals in the figure are: 1: driving mechanism A; 2: fixed support; 3: ball screw I; 4: driving mechanism B; 5: fastening bolt I; 6: output shaft; 7: piezoelectric chip; 8: linear driving mechanism; 9: ball screw II; 10: rotary driving mechanism; 11: fastening bolt II; 12: fastening threaded hole II; 13: output end I; 14: driving hinge I; 15: hole I; 16: fixed end I; 17: countersunk hole I; 18: countersunk hole II; 19: fixed end II; 20: driving hinge II; 21: output end II; 22: ball screw hole II; 23: hole II; 24: fixed hole; 25: fastening threaded hole I; 26: ball screw hole I; 27: hole III; 28: support frame; 29: fixed foot; 1-1: piezoelectric chip C; 1-2: piezoelectric chip D; 1-3: piezoelectric chip E; 1-4: piezoelectric chip F; 1-5: piezoelectric chip G; 1-6: piezoelectric chip H; 1-7: piezoelectric chip J; 1-8: piezoelectric chip K; 2-1: piezoelectric chip c; 2-2: piezoelectric chip d; 2-3: piezoelectric chip e; 2-4: piezoelectric chip f; 2-5: piezoelectric chip g; 2-6: piezoelectric chip h; 2-7: piezoelectric chip j; 2-8: piezoelectric chip k. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are protected by the present application.

[0015] like Figure 1-8 As shown, a friction differential two-degree-of-freedom bionic stepping piezoelectric actuator includes a driving mechanism A1, a driving mechanism B4, a fixed support 2 and an output shaft 6; The fixed support 2 includes a support frame 28 and two fixed feet 29, the two fixed feet 29 are symmetrically connected to the two sides of the support frame 28, a hole III27 is provided in the center of the support frame 28, four fastening threaded holes I25 are evenly distributed around the support frame 28, and each fixed foot 29 is provided with a fixing hole 24 to fix the entire actuator to the working plane; The driving mechanism B4 includes four pairs of piezoelectric chips 7, a linear driving mechanism 8 and a rotary driving mechanism 10; The linear drive mechanism 8 includes two output terminals I13, two drive hinges I14 and a fixed terminal I16. One end of the two drive hinges I14 is fixedly connected to one output terminal I13 respectively, and the other ends of the two drive hinges I14 are fixedly connected to the fixed terminal I16. A hole I15 is opened in the center of the fixed terminal I16. Four countersunk holes I17 corresponding to the fastening threaded holes I25 are evenly distributed around the fixed terminal I16. Four fastening bolts I5 pass through the countersunk holes I17 respectively and are installed in the fastening threaded holes I25, so as to fix the linear drive mechanism 8 to the fixed support 2. Two fastening threaded holes II12 are processed on the two output terminals I13. The rotary drive mechanism 10 includes two fixed ends II19, two driving hinges II20 and an output end II21. One end of the two driving hinges II20 is fixedly connected to a fixed end II19 respectively, and the other end of the two driving hinges II20 is fixedly connected to the output end II21. A hole II23 is opened in the center of the output end II21. The two fixed ends II19 are processed with two countersunk holes II18 corresponding to the fastening threaded holes II12. Four fastening bolts II11 pass through the countersunk holes II18 respectively and are installed in the fastening threaded holes II12, so as to fix the rotary drive mechanism 10 with the linear drive mechanism 8. Four pairs of piezoelectric wafers 7 are glued to both sides of two driving hinges I14 and two driving hinges II20 respectively; The drive mechanism A1 and the drive mechanism B4 have the same structural configuration and are symmetrically installed on both sides of the fixed support 2; The output shaft 6 passes through the hole II23, the hole I15 and the hole III27 in sequence, and is in frictional contact with the hole II23 and the hole III27; The driving mechanism A1 and the driving mechanism B4 can complete the displacement along the X-axis or the rotation around the X-axis in a timely manner. The intervention of the fixed support 2 enables the driving mechanism A1 and the driving mechanism B4 to drive the output shaft 6 to produce displacement or rotation, and then retreat to the initial state one by one without affecting the output shaft 6. The process is repeated continuously, and the output shaft 6 can realize a large-stroke cross-scale stepping linear motion or stepping rotational motion.

[0016] Furthermore, the two pairs of piezoelectric chips 7 used in the linear drive mechanism 8 included in the drive mechanism B4 are piezoelectric chip g2-5, piezoelectric chip h2-6, piezoelectric chip j2-7 and piezoelectric chip k2-8; The piezoelectric chip g2-5 and the piezoelectric chip h2-6 are symmetrically glued on both sides of the driving hinge I14; The piezoelectric chip j2-7 and the piezoelectric chip k2-8 are symmetrically glued on both sides of the driving hinge I14; The two pairs of piezoelectric chips 7 used in the rotation drive mechanism 10 included in the drive mechanism B4 are piezoelectric chip c2-1, piezoelectric chip d2-2, piezoelectric chip e2-3 and piezoelectric chip f2-4 respectively; The piezoelectric chip c2-1 and the piezoelectric chip d2-2 are symmetrically glued on both sides of the driving hinge II20; The piezoelectric chip e2-3 and the piezoelectric chip f2-4 are symmetrically glued on both sides of the driving hinge II20.

[0017] Furthermore, the two pairs of piezoelectric chips 7 used in the linear drive mechanism 8 included in the drive mechanism A1 are piezoelectric chip G1-5, piezoelectric chip H1-6, piezoelectric chip J1-7 and piezoelectric chip K1-8; The two pairs of piezoelectric chips 7 used in the rotation drive mechanism 10 included in the drive mechanism A1 are piezoelectric chip C1-1, piezoelectric chip D1-2, piezoelectric chip E1-3 and piezoelectric chip F1-4; Since the structural configurations of drive mechanism A1 and drive mechanism B4 are exactly the same, the installation positions of piezoelectric chip G1-5, piezoelectric chip H1-6, piezoelectric chip J1-7, piezoelectric chip K1-8, piezoelectric chip C1-1, piezoelectric chip D1-2, piezoelectric chip E1-3 and piezoelectric chip F1-4 used in drive mechanism A1 will not be repeated here.

[0018] Furthermore, two ball-end screw holes I26 are provided at the center of the top and bottom of the support frame 28; two ball-end screws I3 are respectively installed in the ball-end screw holes I26 at the top and bottom of the fixed support 2, and are in friction contact with the output shaft 6. The ball-end screws I3 are used to adjust the friction preload between the fixed support 2 and the output shaft 6.

[0019] Furthermore, two ball-end screw holes II22 are provided at the top and bottom centers of the output end II21, and four ball-end screws II9 are respectively installed in the ball-end screw holes II22 at the top and bottom of the rotary drive mechanism 10 and in frictional contact with the output shaft 6. The ball-end screws II9 are used to adjust the friction preload between the rotary drive mechanism 10 and the output shaft 6.

[0020] Furthermore, the linear drive mechanism 8 and the rotary drive mechanism 10 are both integrally machined from a whole piece of elastic metal material.

[0021] Working principle of the present invention: like Figure 1 As shown, in the initial state, by adjusting two ball screws I3 and four ball screws II9, the friction preload between the drive mechanism A1, the drive mechanism B4 and the fixed support 2 and the output shaft 6 is kept consistent, that is, the maximum static friction force / maximum friction torque between the drive mechanism A1, the drive mechanism B4 and the fixed support 2 and the output shaft 6 is equal; like Figure 1 , Figure 2 , Figure 4 and Figure 6-7 As shown, during linear stepping motion, the piezoelectric chip H1-6 and the piezoelectric chip J1-7 are used as follows Figure 6 (a) shows the type I control voltage, the piezoelectric chip G1-5 and the piezoelectric chip K1-8 adopt the following Figure 6 (a) shows the type II control voltage, the piezoelectric chip g2-5 and the piezoelectric chip k2-8 adopt the following Figure 6 (b) The I-type control voltage shown, the piezoelectric chip h2-6 and the piezoelectric chip j2-7 adopt the following Figure 6 (b) The type II control voltage shown, under the drive of the control voltage signal, the four pairs of piezoelectric chips produce time-sequential displacement by controlling the output terminals II21 of the drive mechanism A1 and the drive mechanism B4, and complete the linear stepping motion in an orderly manner; The specific motion process of the linear stepping motion of the present invention is as follows: 1. During the 0-T / 3 process, the voltages of the piezoelectric chips H1-6, J1-7, g2-5 and k2-8 increase linearly from 0 to U, and the voltages of the piezoelectric chips G1-5, K1-8, h2-6 and j2-7 decrease linearly from 0 to -U; Figure 1-5 and Figure 7As shown, under the action of the inverse piezoelectric effect, the piezoelectric chips H1-6, J1-7, g2-5 and k2-8 gradually extend, and the piezoelectric chips G1-5, K1-8, h2-6 and j2-7 gradually shorten, driving the driving hinge I14 to bend, thereby driving the driving mechanism A1 and the driving mechanism B4 to simultaneously generate a positive displacement ∆L along the X-axis. Since the maximum static friction between the driving mechanism A1, the driving mechanism B4 and the fixed support 2 and the output shaft 6 is equal, the static friction applied by the driving mechanism A1 and the driving mechanism B4 to the output shaft 6 along the positive direction of the X-axis is greater than the maximum static friction applied by the fixed support 2 to the output shaft 6 along the negative direction of the X-axis. Therefore, in the 0-T / 3 process, the output shaft 6 moves with the driving mechanism A1 and the driving mechanism B4, and the output displacement ∆L along the X-axis is generated; 2. During the T / 3-2T / 3 process, the voltage of the piezoelectric chip H1-6 and the piezoelectric chip J1-7 decreases linearly from U to 0, the voltage of the piezoelectric chip G1-5 and the piezoelectric chip K1-8 increases linearly from -U to 0, and the voltage of the piezoelectric chip g2-5, the piezoelectric chip h2-6, the piezoelectric chip j2-7 and the piezoelectric chip k2-8 remain unchanged; Figure 1-5 and Figure 7 As shown, under the inverse piezoelectric effect, the piezoelectric chips g2-5, h2-6, j2-7 and k2-8 remain unchanged, and the piezoelectric chips G1-5, H1-6, J1-7 and K1-8 gradually return to their initial states, driving the drive mechanism A1 to generate a negative displacement ∆L along the X-axis. Since the maximum static friction between the drive mechanism A1, the drive mechanism B4, the fixed support 2 and the output shaft 6 is equal, the static friction applied by the fixed support 2 and the drive mechanism B4 to the output shaft 6 along the positive direction of the X-axis is greater than the maximum static friction applied by the drive mechanism A1 to the output shaft 6 along the negative direction of the X-axis. Therefore, during the T / 3-2T / 3 process, the output shaft 6 remains stationary; 3. In the 2T / 3-T process, the voltage of the piezoelectric chip g2-5 and the piezoelectric chip k2-8 decreases linearly from U to 0, the voltage of the piezoelectric chip h2-6 and the piezoelectric chip j2-7 increases linearly from -U to 0, and the voltage of the piezoelectric chip G1-5, the piezoelectric chip H1-6, the piezoelectric chip J1-7 and the piezoelectric chip K1-8 remain unchanged; Figure 1-5 and Figure 7As shown, under the inverse piezoelectric effect, the piezoelectric chips G1-5, H1-6, J1-7 and K1-8 remain unchanged, and the piezoelectric chips g2-5, h2-6, j2-7 and k2-8 gradually return to their initial states, driving the drive mechanism B4 to generate a negative displacement ∆L along the X-axis. Since the maximum static friction between the drive mechanism A1, the drive mechanism B4, the fixed support 2 and the output shaft 6 is equal, the static friction applied by the drive mechanism A1 and the fixed support 2 to the output shaft 6 along the positive direction of the X-axis is greater than the maximum static friction applied by the drive mechanism B4 to the output shaft 6 along the negative direction of the X-axis. Therefore, during the 2T / 3-T process, the output shaft 6 remains stationary; After a cycle of the actuator, the drive mechanism A1 and the drive mechanism B4 can sequentially complete the displacement along the X-axis. The intervention of the fixed support 2 enables the drive mechanism A1 and the drive mechanism B4 to drive the output shaft 6 to produce displacement, and then retreat to the initial state one by one without affecting the output shaft 6, thereby replacing the clamping mechanism to drive the output shaft to complete a step-length linear motion along the positive direction of the X-axis. The process is repeated continuously, and the output shaft 6 can achieve a large-stroke cross-scale stepping linear motion. By applying the reverse driving voltage of the piezoelectric chip, the stepping motion of the output shaft 6 along the negative direction of the X-axis can be achieved, which will not be repeated here.

[0022] like Figure 1 , Figure 6 and Figure 8 As shown, during the rotational stepping motion, the piezoelectric chip C1-1 and the piezoelectric chip E1-3 adopt the following Figure 6 (a) Type II control voltage, piezoelectric chip D1-2 and piezoelectric chip F1-4 adopt the following Figure 6 (a) shows the type I control voltage, the piezoelectric chip c2-1 and the piezoelectric chip e2-3 adopt the following Figure 6 (b) The I-type control voltage shown, the piezoelectric chip d2-2 and the piezoelectric chip f2-4 adopt the following Figure 6 (b) The type II control voltage shown, under the drive of the control voltage signal, the four pairs of piezoelectric chips produce timed rotation by controlling the output terminals II21 of the drive mechanism A1 and the drive mechanism B4, and complete the rotation stepping motion in an orderly manner; The specific motion process of the rotary stepping motion of the present invention is as follows: 1. In the 0-T / 3 process, the voltage of the piezoelectric chip D1-2, the piezoelectric chip F1-4, the piezoelectric chip c2-1 and the piezoelectric chip e2-3 rises linearly from 0 to U, and the voltage of the piezoelectric chip C1-1, the piezoelectric chip E1-3, the piezoelectric chip d2-2 and the piezoelectric chip f2-4 drops linearly from 0 to -U; Figure 1-5 and Figure 8As shown, under the action of the inverse piezoelectric effect, the piezoelectric chip D1-2, the piezoelectric chip F1-4, the piezoelectric chip c2-1 and the piezoelectric chip e2-3 gradually extend, and the piezoelectric chip C1-1, the piezoelectric chip E1-3, the piezoelectric chip d2-2 and the piezoelectric chip f2-4 gradually shorten, driving the driving hinge II20 to bend, thereby driving the output end II21 of the driving mechanism A1 and the driving mechanism B4 to simultaneously generate a counterclockwise rotation angle ∆φ around the X-axis. Since the maximum static friction torque between the driving mechanism A1, the driving mechanism B4 and the fixed support 2 and the output shaft 6 is equal, the static friction torque applied by the driving mechanism A1 and the driving mechanism B4 to the output shaft 6 counterclockwise around the X-axis is greater than the maximum static friction torque applied by the fixed support 2 to the output shaft 6 clockwise around the X-axis. Therefore, in the 0-T / 3 process, the output shaft 6 rotates with the driving mechanism A1 and the driving mechanism B4, and the output rotates counterclockwise around the X-axis by an angle ∆φ; 2. During the T / 3-2T / 3 process, the voltage of the piezoelectric chip D1-2 and the piezoelectric chip F1-4 decreases linearly from U to 0, the voltage of the piezoelectric chip C1-1 and the piezoelectric chip E1-3 increases linearly from -U to 0, and the voltage of the piezoelectric chip c2-1, the piezoelectric chip d2-2, the piezoelectric chip e2-3 and the piezoelectric chip f2-4 remain unchanged; Figure 1-5 and Figure 8 As shown, under the action of the inverse piezoelectric effect, the piezoelectric chip c2-1, the piezoelectric chip d2-2, the piezoelectric chip e2-3 and the piezoelectric chip f2-4 remain unchanged, and the piezoelectric chip C1-1, the piezoelectric chip D1-2, the piezoelectric chip E1-3 and the piezoelectric chip F1-4 gradually return to the initial state, driving the output end II21 of the driving mechanism A1 to rotate around the X-axis clockwise by an angle ∆φ. Since the maximum static friction torques between the driving mechanism A1, the driving mechanism B4 and the fixed support 2 and the output shaft 6 are equal, the static friction torque applied by the fixed support 2 and the driving mechanism B4 to the output shaft 6 counterclockwise around the X-axis is greater than the maximum static friction torque applied by the driving mechanism A1 to the output shaft 6 clockwise around the X-axis. Therefore, during the 0-T / 3 process, the output shaft 6 remains stationary; 3. In the 2T / 3-T process, the voltage of the piezoelectric chip c2-1 and the piezoelectric chip e2-3 decreases linearly from U to 0, the voltage of the piezoelectric chip d2-2 and the piezoelectric chip f2-4 increases linearly from -U to 0, and the voltage of the piezoelectric chip C1-1, the piezoelectric chip D1-2, the piezoelectric chip E1-3 and the piezoelectric chip F1-4 remain unchanged; Figure 1-5 and Figure 8As shown, under the action of the inverse piezoelectric effect, the piezoelectric chip C1-1, the piezoelectric chip D1-2, the piezoelectric chip E1-3 and the piezoelectric chip F1-4 remain unchanged, and the piezoelectric chip c2-1, the piezoelectric chip e2-3, the piezoelectric chip d2-2 and the piezoelectric chip f2-4 gradually return to the initial state, driving the output end II21 of the driving mechanism B4 to rotate around the X-axis clockwise by an angle ∆φ. Since the maximum static friction torque between the driving mechanism A1, the driving mechanism B4 and the fixed support 2 and the output shaft 6 is equal, the static friction torque applied by the driving mechanism A1 and the fixed support 2 to the output shaft 6 counterclockwise around the X-axis is greater than the maximum static friction torque applied by the driving mechanism B4 to the output shaft 6 clockwise around the X-axis. Therefore, during the 0-T / 3 process, the output shaft 6 remains stationary; After a cycle of the actuator, the drive mechanism A1 and the drive mechanism B4 can complete the rotation around the X-axis in sequence. The intervention of the fixed support 2 enables the drive mechanism A1 and the drive mechanism B4 to drive the output shaft 6 to rotate, and then retreat to the initial state one by one without affecting the output shaft 6, thereby replacing the clamping mechanism to drive the output shaft to complete a step-length rotation motion counterclockwise around the X-axis. The process is repeated continuously, and the output shaft 6 can achieve a large-stroke cross-scale step rotation motion. By applying a reverse driving voltage to the piezoelectric chip, the output shaft 6 can achieve a clockwise stepping motion around the X-axis, which will not be repeated here.

[0023] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A friction differential two-degree-of-freedom bionic stepping piezoelectric actuator, characterized in that: It comprises a driving mechanism A (1), a driving mechanism B (4), a fixed support (2) and an output shaft (6); The fixed support (2) comprises a support frame (28) and two fixed feet (29), the two fixed feet (29) are symmetrically connected to two sides of the support frame (28), and a hole III (27) is provided in the center of the support frame (28); The driving mechanism B (4) comprises four pairs of piezoelectric chips (7), a linear driving mechanism (8) and a rotary driving mechanism (10); The linear drive mechanism (8) comprises two output ends I (13), two drive hinges I (14) and a fixed end I (16), one end of each of the two drive hinges I (14) being fixedly connected to one of the output ends I (13), the other ends of each of the two drive hinges I (14) being fixedly connected to the fixed end I (16), and a hole I (15) being formed in the center of the fixed end I (16); The rotary drive mechanism (10) comprises two fixed ends II (19), two driving hinges II (20) and an output end II (21), one end of each of the two driving hinges II (20) being fixedly connected to one of the fixed ends II (19), the other ends of each of the two driving hinges II (20) being fixedly connected to the output end II (21), and a hole II (23) being formed in the center of the output end II (21); Four pairs of piezoelectric chips (7) are respectively connected to two sides of two driving hinges I (14) and two driving hinges II (20); The drive mechanism A (1) and the drive mechanism B (4) have completely identical structural configurations and are symmetrically mounted on both sides of the fixed support (2); The output shaft (6) passes through hole II (23), hole I (15) and hole III (27) in sequence, and is in frictional contact with hole II (23) and hole III (27); The drive mechanism A (1) and the drive mechanism B (4) can sequentially complete displacement along the X-axis or rotation around the X-axis. The fixed support (2) is introduced so that the drive mechanism A (1) and the drive mechanism B (4) can drive the output shaft (6) to generate displacement or rotation, and then return to the initial state one by one without affecting the output shaft (6). The process is repeated continuously in a cycle, and the output shaft (6) can then achieve cross-scale stepping linear motion or stepping rotational motion.

2. The friction differential two-degree-of-freedom bionic stepping piezoelectric actuator according to claim 1, characterized in that: Four fastening threaded holes I (25) are evenly distributed around the support frame (28), and each fixing foot (29) is provided with a fixing hole (24) for fixing the entire actuator to the working plane; Four countersunk holes I (17) corresponding to the fastening threaded holes I (25) are evenly distributed around the fixed end I (16); four fastening bolts I (5) pass through the countersunk holes I (17) and are installed in the fastening threaded holes I (25), thereby fixing the linear drive mechanism (8) to the fixed support (2); two output ends I (13) are each processed with two fastening threaded holes II (12); The two fixed ends II (19) are each processed with two countersunk holes II (18) corresponding to the fastening threaded holes II (12), and four fastening bolts II (11) respectively pass through the countersunk holes II (18) and are installed in the fastening threaded holes II (12), thereby fixedly connecting the rotary drive mechanism (10) and the linear drive mechanism (8).

3. The friction differential two-degree-of-freedom bionic stepping piezoelectric actuator according to claim 1, characterized in that: Two ball screw holes I (26) are provided at the center of the top and bottom of the support frame (28); two ball screws I (3) are respectively installed in the ball screw holes I (26) at the top and bottom of the fixed support (2) and are in frictional contact with the output shaft (6); the ball screws I (3) are used to adjust the friction preload between the fixed support (2) and the output shaft (6).

4. The friction differential two-degree-of-freedom bionic stepping piezoelectric actuator according to claim 1, characterized in that: Two ball screw holes II (22) are provided at the top and bottom centers of the output end II (21). Four ball screws II (9) are respectively installed in the ball screw holes II (22) at the top and bottom of the rotary drive mechanism (10) and are in frictional contact with the output shaft (6). The ball screws II (9) are used to adjust the friction preload between the rotary drive mechanism (10) and the output shaft (6).

5. The friction differential two-degree-of-freedom bionic stepping piezoelectric actuator according to claim 1, characterized in that: The linear drive mechanism (8) and the rotary drive mechanism (10) are both integrally machined from a single piece of elastic metal material.

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