A bionic stepping planar universal piezoelectric positioning platform based on differential friction drive

Abstract

The present invention discloses a bionic stepping planar universal piezoelectric positioning platform based on differential friction drive, belonging to the field of precision drive technology, which includes a nested unit A, a nested unit B, a nested unit C and a connecting seat; the nested unit C includes four pairs of piezoelectric wafers, an outer drive mechanism, an inner drive mechanism and drive feet; by controlling the sequential excitation of the piezoelectric wafers with voltage, the inner drive mechanism and the outer drive mechanism in the three nested units generate sequential deformations, so that the drive feet generate sequential displacements under the action of the friction difference, and further realize the universal stepping displacement output of the positioning platform in the plane and the stepping rotation displacement output around its own central axis.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision drive, and particularly relates to a bionic stepping planar universal piezoelectric positioning platform based on differential friction drive. Background Art

[0002] With the continuous development of technical fields such as aerospace, life science, precision instruments, and semiconductor manufacturing, the demand for precision drive in modes such as micro-displacement, high resolution, large stroke, and compact structure is also increasing day by day. Traditional precision drive technologies mostly use a combination of mechanical, fluid, and electromagnetic technologies to achieve, but due to the limitations of their working principles, it is difficult to meet drive requirements such as high resolution and compact structure. Piezoelectric drive is based on the inverse piezoelectric effect of piezoelectric materials. By applying a voltage, the mechanical deformation of the piezoelectric materials is controlled to generate rotational or linear motion. Piezoelectric drive has quickly become a popular research direction in the new field of precision drive technology due to its characteristics such as fast response speed, high resolution, and large stroke. Most of the existing piezoelectric drive technologies only achieve single-degree-of-freedom and two-degree-of-freedom motions and often produce large parasitic displacements, which are not conducive to precision drive. There is a lack of a piezoelectric drive mechanism that can integrate the output of universal displacement and rotation in a plane.

[0003] Based on the differential friction principle, the present invention theoretically eliminates parasitic displacements and has a compact structure design, enabling the driving feet to have universal displacement in a plane, thereby realizing the universal stepping displacement output of the positioning platform in the plane and the stepping rotation displacement output around its own central axis. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art that when the piezoelectric drive mechanism works, large parasitic displacements are generated, which are not conducive to precision drive; and there is a lack of a piezoelectric drive mechanism that can integrate the output of universal displacement and rotation in a plane.

[0005] A bionic stepping planar universal piezoelectric positioning platform based on differential friction drive includes a nested unit A, a nested unit B, a nested unit C, and a connecting seat;

[0006] The nested unit A, the nested unit B, and the nested unit C have the same structure, and the three nested units are evenly distributed on the same circumference;

[0007] The nested unit C includes four pairs of piezoelectric wafers, an outer drive mechanism, an inner drive mechanism, and a driving foot;

[0008] The outer drive mechanism includes a driving end Ⅰ, two plate-shaped flexible hinges Ⅰ, a support seat, and a connecting table Ⅰ. The support seat is provided with a rectangular through-hole. The first ends of the two plate-shaped flexible hinges Ⅰ are respectively fixedly connected to both sides of the driving end Ⅰ, the second ends of the two plate-shaped flexible hinges Ⅰ are respectively fixedly connected to both sides of the support seat, and the connecting table Ⅰ is connected to the support seat;

[0009] The inner driving mechanism includes a connecting platform II, two plate-shaped flexible hinges II, and a driving end II. The ends of the two plate-shaped flexible hinges II are respectively fixedly connected to both sides of the driving end II, and the heads of the two plate-shaped flexible hinges II are respectively fixedly connected to both sides of the connecting platform II. The upper end of the outer driving mechanism is fixedly connected to the upper end of the inner driving mechanism, and a fastening threaded hole II is opened at the center of the driving end II;

[0010] The driving foot is installed in the fastening threaded hole II;

[0011] Piezoelectric wafers are adhesively bonded to both sides of the two plate-shaped flexible hinges I and the two plate-shaped flexible hinges II;

[0012] By controlling the sequential excitation of the piezoelectric wafers by voltage, the inner driving mechanism and the outer driving mechanism in the three nested units generate sequential deformations, so that the driving foot generates sequential displacements under the action of the friction difference, and further realizes the universal stepping displacement output of the positioning platform in the plane and the stepping rotation displacement output around its own central axis.

[0013] Preferably, the connecting seat includes a base and three connecting platforms III. The base is provided with a central hole and three through holes II. The three through holes II are evenly distributed in a circular pattern outside the central hole. The central hole and the three through holes II are used for installing the loading platform later. The three connecting platforms III are evenly distributed on the same circumference and fixedly connected to the base. Two fastening threaded holes III are opened on each of the three connecting platforms III for connecting the nested unit A, the nested unit B, and the nested unit C.

[0014] Preferably, the driving end I is provided with a rectangular through slot, and two through holes I are provided on the driving end I. The connecting platform II is provided with a rectangular through slot, and two fastening threaded holes I corresponding to the through holes I are machined on the connecting platform II. Two fastening bolts II respectively pass through the through holes I and are installed in the fastening threaded holes I, so that the upper surface of the rectangular through slot of the driving end I and the lower surface of the rectangular through slot of the connecting platform II are closely attached.

[0015] Preferably, the connecting platform I is provided with two counterbored holes corresponding to the fastening threaded holes III. Two fastening bolts I respectively pass through the counterbored holes and are installed in the fastening threaded holes III, thereby fixedly connecting the nested unit C and the connecting seat.

[0016] Preferably, the nested unit C further includes a fastening nut. The driving foot is threadedly connected with the fastening nut. The driving foot is a ceramic ball screw, and a ceramic ball is installed at the bottom of the screw.

[0017] Preferably, the length and width of the rectangular through hole in the outer driving mechanism are respectively greater than the length and width of the driving end II in the inner driving mechanism, ensuring that the driving end II in the inner driving mechanism can displace in the rectangular through hole of the outer driving mechanism.

[0018] Preferably, both the outer driving mechanism and the inner driving mechanism are integrally machined from a single piece of elastic metal material.

[0019] Advantages of the present invention:

[0020] By controlling the sequential excitation of the piezoelectric wafers with voltage, the inner driving mechanism and the outer driving mechanism in the three centrally symmetrically distributed nested units generate sequential deformations, so that the driving feet generate sequential displacements under the action of the friction difference, and further realize the omnidirectional stepping displacement output of the positioning platform in the plane and the stepping rotation displacement output around its own central axis. Parasitic displacement is theoretically eliminated, providing a new idea for the design of a piezoelectric driving mechanism that can integrate omnidirectional displacement and rotation output in the plane. Description of the drawings

[0021] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 is an exploded perspective view of the nested unit of the present invention;

[0023] Figure 3 is a schematic perspective view of the outer driving mechanism of the present invention;

[0024] Figure 4 is a schematic perspective view of the inner driving mechanism of the present invention;

[0025] Figure 5 is a schematic perspective view of the connecting seat of the present invention;

[0026] Figure 6 is a cross-sectional view of the overall structure of the present invention;

[0027] Figure 7 is a bottom view of the overall structure of the present invention;

[0028] Figure 8 is a working principle diagram of the nested unit of the present invention;

[0029] Figure 9 is a working principle diagram of the present invention for outputting a stepping linear displacement in the positive X-axis direction;

[0030] Figure 10 is a working principle diagram of the present invention for outputting a stepping linear displacement in the positive Y-axis direction;

[0031] Figure 11 is a working principle diagram of the present invention for outputting a stepping rotational displacement in the clockwise direction around the Z-axis;

[0032] Figure 12 is a driving signal diagram of the present invention for outputting a stepping linear displacement along the X and Y axes; where e, f, and g are out-of-phase trapezoidal waveform diagrams, and h and i are out-of-phase triangular waveform diagrams;

[0033] Figure 13It is a driving signal diagram for the clockwise output of the stepping rotational displacement of the present invention around the Z-axis; where j and k are out-of-phase trapezoidal waveforms, and m is an out-of-phase triangular waveform;

[0034] Among them, each reference numeral:

[0035] 1: Nested unit A; 2: Nested unit B; 3: Nested unit C; 4: Fastening bolt I; 5: Connecting seat; 6: Fastening bolt II; 7: External drive mechanism; 8: Piezoelectric wafer; 9: Fastening nut; 10: Internal drive mechanism; 11: Driving foot; 12: Through hole I; 13: Driving end I; 14: Plate-type flexible hinge I; 15: Rectangular through hole; 16: Support seat; 17: Countersunk hole; 18: Connecting platform I; 19: Fastening threaded hole I; 20: Connecting platform II; 21: Plate-type flexible hinge II; 22: Fastening threaded hole II; 23: Driving end II; 24: Connecting platform III; 25: Fastening threaded hole III; 26: Base; 27: Central hole; 28: Through hole II;

[0036] 1-1: Piezoelectric wafer D; 1-2: Piezoelectric wafer E; 1-3: Piezoelectric wafer F; 1-4: Piezoelectric wafer G; 1-5: Piezoelectric wafer H; 1-6: Piezoelectric wafer I; 1-7: Piezoelectric wafer J; 1-8: Piezoelectric wafer K;

[0037] 2-1: Piezoelectric wafer L; 2-2: Piezoelectric wafer M; 2-3: Piezoelectric wafer N; 2-4: Piezoelectric wafer O; 2-5: Piezoelectric wafer P; 2-6: Piezoelectric wafer Q; 2-7: Piezoelectric wafer R; 2-8: Piezoelectric wafer S;

[0038] 3-1: Piezoelectric wafer n; 3-2: Piezoelectric wafer o; 3-3: Piezoelectric wafer p; 3-4: Piezoelectric wafer q; 3-5: Piezoelectric wafer r; 3-6: Piezoelectric wafer s; 3-7: Piezoelectric wafer u; 3-8: Piezoelectric wafer w. Detailed implementation manners

[0039] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to 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 used to limit the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0040] As Figures 1 - 7 shown, a bionic stepping planar universal piezoelectric positioning platform based on differential friction drive includes a nested unit A1, a nested unit B2, a nested unit C3 and a connecting seat 5;

[0041] The connecting base 5 includes a base 26 and three connecting platforms III 24. The base 26 is provided with a central hole 27 and three through holes II 28. The three through holes II 28 are evenly distributed in a circumferential manner outside the central hole 27. The central hole 27 and the three through holes II 28 are used for installing a load platform in the later stage. The three connecting platforms III 24 are evenly distributed on the same circumference and fixedly connected to the base 26. Two fastening threaded holes III 25 are opened on each of the three connecting platforms III 24, which are used to connect the nested unit A1, the nested unit B2, and the nested unit C3;

[0042] The nested unit C3 includes four pairs of piezoelectric wafers 8, an outer driving mechanism 7, an inner driving mechanism 10, a fastening nut 9, and a driving foot 11;

[0043] The outer driving mechanism 7 includes a driving end I 13, two plate-shaped flexible hinges I 14, a support seat 16, and a connecting platform I 18. The driving end I 13 is provided with a rectangular through slot. The support seat 16 is provided with a rectangular through hole 15. The first ends of the two plate-shaped flexible hinges I 14 are respectively fixedly connected to both sides of the driving end I 13. The second ends of the two plate-shaped flexible hinges I 14 are respectively fixedly connected to both sides of the support seat 16. The connecting platform I 18 is connected to the support seat 16. The connecting platform I 18 is provided with two counterbore holes 17 corresponding to the fastening threaded holes III 25. Two fastening bolts I 4 respectively pass through the counterbore holes 17 and are installed in the fastening threaded holes III 25, thereby fixedly connecting the nested unit C3 and the connecting base 5. The driving end I 13 is provided with two through holes I 12;

[0044] The inner driving mechanism 10 includes a connecting platform II 20, two plate-shaped flexible hinges II 21, and a driving end II 23. The connecting platform II 20 is provided with a rectangular through slot. The second ends of the two plate-shaped flexible hinges II 21 are respectively fixedly connected to both sides of the driving end II 23. The first ends of the two plate-shaped flexible hinges II 21 are respectively fixedly connected to both sides of the connecting platform II 20. Two fastening threaded holes I 19 corresponding to the through holes I 12 are machined on the connecting platform II 20. Two fastening bolts II 6 respectively pass through the through holes I 12 and are installed in the fastening threaded holes I 19, so that the upper surface of the rectangular through slot of the driving end I 13 and the lower surface of the rectangular through slot of the connecting platform II 20 are closely attached, thereby fixedly connecting the outer driving mechanism 7 and the inner driving mechanism 10. A fastening threaded hole II 22 is opened at the center of the driving end II 23;

[0045] The driving foot 11 is a ceramic ball screw, and a ceramic ball is installed at the bottom of the screw. The driving foot 11 passes through the fastening nut 9 and is installed in the fastening threaded hole II 22, thereby fixedly connecting the driving foot 11 to the inner driving mechanism 10;

[0046] Piezoelectric wafers 8 are glued to both sides of the two plate-shaped flexible hinges I 14 and the two plate-shaped flexible hinges II 21;

[0047] The nested unit B2, the nested unit A1, and the nested unit C3 have exactly the same structural configuration. The three nested units are evenly distributed on the same circumference and are installed on the connecting platform III 24 of the connecting seat 5;

[0048] By controlling the sequential excitation of the piezoelectric wafers with voltage, the inner drive mechanism 10 and the outer drive mechanism 7 in the three nested units generate sequential deformations, so that the driving feet 11 generate sequential displacements under the action of the friction force difference, and further realize the universal stepping displacement output of the positioning platform in the plane and the stepping rotation displacement output around its own central axis.

[0049] As Figure 2 、 Figure 3 、 Figure 6 、 Figure 7 shown, furthermore, the two pairs of piezoelectric wafers 8 used by the outer drive mechanism 7 included in the nested unit C3 are piezoelectric wafer n3-1, piezoelectric wafer o3-2, piezoelectric wafer u3-7, and piezoelectric wafer w3-8 respectively;

[0050] The piezoelectric wafer n3-1 and the piezoelectric wafer o3-2 are symmetrically glued to both sides of a plate-type flexible hinge I 14;

[0051] The piezoelectric wafer u3-7 and the piezoelectric wafer w3-8 are symmetrically glued to both sides of another plate-type flexible hinge I 14;

[0052] The two pairs of piezoelectric wafers 8 used by the inner drive mechanism 10 included in the nested unit C3 are piezoelectric wafer p3-3, piezoelectric wafer q3-4, piezoelectric wafer r3-5, and piezoelectric wafer s3-6 respectively;

[0053] The piezoelectric wafer p3-3 and the piezoelectric wafer q3-4 are symmetrically glued to both sides of a plate-type flexible hinge II 21;

[0054] The piezoelectric wafer r3-5 and the piezoelectric wafer s3-6 are symmetrically glued to both sides of another plate-type flexible hinge II 21;

[0055] The two pairs of piezoelectric wafers 8 used by the outer drive mechanism 7 included in the nested unit A1 are piezoelectric wafer F1-3, piezoelectric wafer G1-4, piezoelectric wafer H1-5, and piezoelectric wafer I1-6 respectively;

[0056] The piezoelectric wafer F1-3 and the piezoelectric wafer G1-4 are symmetrically glued to both sides of a plate-type flexible hinge I 14;

[0057] The piezoelectric wafer H1-5 and the piezoelectric wafer I1-6 are symmetrically glued to both sides of another plate-type flexible hinge I 14;

[0058] The two pairs of piezoelectric wafers 8 used by the inner driving mechanism 10 included in the nested unit A1 are piezoelectric wafer D1-1, piezoelectric wafer E1-2, piezoelectric wafer J1-7, and piezoelectric wafer K1-8 respectively;

[0059] Piezoelectric wafer D1-1 and piezoelectric wafer E1-2 are symmetrically glued to both sides of a plate-shaped flexible hinge II 21;

[0060] Piezoelectric wafer J1-7 and piezoelectric wafer K1-8 are symmetrically glued to both sides of another plate-shaped flexible hinge II 21;

[0061] The two pairs of piezoelectric wafers 8 used by the outer driving mechanism 7 included in the nested unit B2 are piezoelectric wafer N2-3, piezoelectric wafer O2-4, piezoelectric wafer P2-5, and piezoelectric wafer Q2-6 respectively;

[0062] Piezoelectric wafer N2-3 and piezoelectric wafer O2-4 are symmetrically glued to both sides of a plate-shaped flexible hinge I 14;

[0063] Piezoelectric wafer P2-5 and piezoelectric wafer Q2-6 are symmetrically glued to both sides of another plate-shaped flexible hinge I 14;

[0064] The two pairs of piezoelectric wafers 8 used by the inner driving mechanism 10 included in the nested unit A1 are piezoelectric wafer L2-1, piezoelectric wafer M2-2, piezoelectric wafer R2-7, and piezoelectric wafer S2-8 respectively;

[0065] Piezoelectric wafer L2-1 and piezoelectric wafer M2-2 are symmetrically glued to both sides of a plate-shaped flexible hinge I 14;

[0066] Piezoelectric wafer R2-7 and piezoelectric wafer S2-8 are symmetrically glued to both sides of another plate-shaped flexible hinge I 14.

[0067] As Figure 3 and Figure 4 shown, furthermore, the length and width of the rectangular through hole 15 in the outer driving mechanism 7 are respectively greater than the length and width of the driving end II 23 in the inner driving mechanism 10, ensuring that the driving end II 23 in the inner driving mechanism 10 can perform a small displacement within the rectangular through hole 15 of the outer driving mechanism 7.

[0068] As Figure 3 and Figure 4 shown, furthermore, both the outer driving mechanism 7 and the inner driving mechanism 10 are integrally processed from a single piece of elastic metal material.

[0069] Working principle of the present invention:

[0070] Referring to Figures 1 - 8 and Figure 12 shown, the driving foot can achieve a circular activity range in the XY plane. Taking the nested unit A1 as an example;

[0071] Apply the type-I signal in f to the piezoelectric wafers E1-2 and K1-8 simultaneously, and apply the type-II signal in f to the piezoelectric wafers D1-1 and J1-7 simultaneously. Figure 12 Apply the type-I signal in f to the piezoelectric wafers E1-2 and K1-8 simultaneously, and apply the type-II signal in f to the piezoelectric wafers D1-1 and J1-7 simultaneously. Figure 12 Apply the type-II signal in f to the piezoelectric wafers G1-4 and I1-6 simultaneously, and apply the type-I signal in h to the piezoelectric wafers F1-3 and H1-5 simultaneously. Figure 12 Apply the type-I signal in h to the piezoelectric wafers F1-3 and H1-5 simultaneously. Figure 12 Apply the type-II signal in h; as Figure 8 shown, within the time period of T / 4 - T / 2, the piezoelectric wafers E1-2 and K1-8 are driven by a positive voltage signal to elongate, and the piezoelectric wafers D1-1 and J1-7 are driven by a negative voltage signal to shorten. Under the combined action of the four piezoelectric wafers, the two plate-type flexible hinges II21 bend in the negative X-axis direction, driving the driving end II23 to displace a distance of t1 in the negative X-axis direction within the rectangular through-hole 15, thereby causing the driving foot 11 to displace from point a to point a'; within the time period of T / 2 - 3T / 4, the piezoelectric wafers G1-4 and I1-6 are driven by a positive voltage signal to elongate, and the piezoelectric wafers F1-3 and H1-5 are driven by a negative voltage signal to shorten. Under the combined action of the four piezoelectric wafers, the two plate-type flexible hinges I14 bend in the positive Y-axis direction, driving the entire inner driving mechanism 10 to displace a distance of t1 in the positive Y-axis direction within the rectangular through-hole 15, thereby causing the driving foot 11 to displace from point a' to point a".

[0072] By controlling the voltage magnitude of the excitation signals applied to each piezoelectric wafer in the nested unit A1, the driving foot 11 can be displaced to any point on the trajectory circle at a", thereby achieving omnidirectional displacement of the driving foot 11 in the plane.

[0073] Refer to Figures 1 - 9 and Figure 12 , taking the example of outputting a stepped linear displacement along the positive X-axis, the specific process is as follows:

[0074] Apply the type-I signal in e to the piezoelectric wafers D1-1 and J1-7 simultaneously, and apply the type-II signal in e to the piezoelectric wafers E1-2 and K1-8 simultaneously; apply the type-I signal in f to the piezoelectric wafers N2-3 and P2-5 simultaneously, and apply the type-II signal in f to the piezoelectric wafers O2-4 and Q2-6 simultaneously; apply the type-I signal in g to the piezoelectric wafers M2-2 and S2-8 simultaneously, and apply the type-II signal in g to the piezoelectric wafers L2-1 and R2-7 simultaneously; apply the type-I signal in g to the piezoelectric wafers n3-1 and u3-7 simultaneously. Figure 12 Apply the type-I signal in e to the piezoelectric wafers D1-1 and J1-7 simultaneously, and apply the type-II signal in e to the piezoelectric wafers E1-2 and K1-8 simultaneously; apply the type-I signal in f to the piezoelectric wafers N2-3 and P2-5 simultaneously, and apply the type-II signal in f to the piezoelectric wafers O2-4 and Q2-6 simultaneously; apply the type-I signal in g to the piezoelectric wafers M2-2 and S2-8 simultaneously, and apply the type-II signal in g to the piezoelectric wafers L2-1 and R2-7 simultaneously; apply the type-I signal in g to the piezoelectric wafers n3-1 and u3-7 simultaneously. Figure 12 Apply the type-II signal in f to the piezoelectric wafers G1-4 and I1-6 simultaneously, and apply the type-I signal in h to the piezoelectric wafers F1-3 and H1-5 simultaneously; apply the type-II signal in f to the piezoelectric wafers O2-4 and Q2-6 simultaneously, and apply the type-I signal in g to the piezoelectric wafers M2-2 and S2-8 simultaneously; apply the type-II signal in g to the piezoelectric wafers L2-1 and R2-7 simultaneously, and apply the type-I signal in g to the piezoelectric wafers n3-1 and u3-7 simultaneously. Figure 12 Apply the type-I signal in f to the piezoelectric wafers N2-3 and P2-5 simultaneously, and apply the type-II signal in f to the piezoelectric wafers O2-4 and Q2-6 simultaneously; apply the type-I signal in g to the piezoelectric wafers M2-2 and S2-8 simultaneously, and apply the type-II signal in g to the piezoelectric wafers L2-1 and R2-7 simultaneously; apply the type-I signal in g to the piezoelectric wafers n3-1 and u3-7 simultaneously. Figure 12 Apply the type-II signal in f to the piezoelectric wafers O2-4 and Q2-6 simultaneously, and apply the type-I signal in g to the piezoelectric wafers M2-2 and S2-8 simultaneously; apply the type-II signal in g to the piezoelectric wafers L2-1 and R2-7 simultaneously, and apply the type-I signal in g to the piezoelectric wafers n3-1 and u3-7 simultaneously. Figure 12 Apply the type-I signal in g to the piezoelectric wafers M2-2 and S2-8 simultaneously, and apply the type-II signal in g to the piezoelectric wafers L2-1 and R2-7 simultaneously; apply the type-I signal in g to the piezoelectric wafers n3-1 and u3-7 simultaneously. Figure 12 Apply the type-II signal in g to the piezoelectric wafers L2-1 and R2-7 simultaneously, and apply the type-I signal in g to the piezoelectric wafers n3-1 and u3-7 simultaneously. Figure 12Type I signal in h, simultaneously apply to piezoelectric wafer o3-2 and piezoelectric wafer w3-8 Figure 12 Type II signal in h; simultaneously apply to piezoelectric wafer p3-3 and piezoelectric wafer r3-5 Figure 12 Type I signal in i, simultaneously apply to piezoelectric wafer q3-4 and piezoelectric wafer s3-6 Figure 12 Type II signal in i;

[0075] 1. During 0 - T / 4, the voltages of piezoelectric wafers D1-1 and J1-7 linearly rise from 0 to U1, and the voltages of piezoelectric wafers E1-2 and K1-8 linearly drop from 0 to -U1; under the action of the inverse piezoelectric effect, piezoelectric wafers D1-1 and J1-7 gradually elongate, and piezoelectric wafers E1-2 and K1-8 gradually shorten. Since the maximum static frictions between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units B2 and C3 are in a static state. Therefore, the maximum reverse static friction exerted by the ground on the driving feet 11 in nested unit A1 is less than the sum of the maximum forward frictions exerted by the ground on the driving feet 11 in nested units B2 and C3. Thus, the center of the positioning platform is stationary, and the two plate-type flexible hinges II21 in nested unit A1 bend, driving the driving end II23 in nested unit A1 to generate a displacement t, so that the driving foot 11 in nested unit A1 displaces from point a to point a1;

[0076] 2. During T / 4 - T / 2, the voltages of piezoelectric wafers N2-3 and P2-5 linearly rise from 0 to U2, and the voltages of piezoelectric wafers O2-4 and Q2-6 linearly drop from 0 to -U2; the voltages of piezoelectric wafers M2-2 and S2-8 linearly rise from 0 to U3, and the voltages of piezoelectric wafers L2-1 and R2-7 linearly drop from 0 to -U3; under the action of the inverse piezoelectric effect, piezoelectric wafers N2-3, P2-5, M2-2, and S2-8 gradually elongate, and piezoelectric wafers O2-4, Q2-6, L2-1, and R2-7 gradually shorten. Since the maximum static frictions between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units A1 and C3 are in a static state. Therefore, the maximum reverse static friction exerted by the ground on the driving feet 11 in nested unit B2 is less than the sum of the maximum forward frictions exerted by the ground on the driving feet 11 in nested units A1 and C3. Thus, the center of the positioning platform is stationary, and the two plate-type flexible hinges II21 in nested unit B2 bend, driving the driving end II23 in nested unit B2 to generate a displacement t2. At the same time, the two plate-type flexible hinges I14 in nested unit B2 bend, driving the entire inner driving mechanism 10 in nested unit B2 to generate a displacement t1. Under the synthesis of displacement t1 and displacement t2, the driving foot 11 in nested unit B2 displaces from point b to point b1;

[0077] 3. During the process of T / 2 - 3T / 4, the voltages of piezoelectric wafers n3 - 1 and u3 - 7 linearly increase from 0 to U2, and the voltages of piezoelectric wafers o3 - 2 and w3 - 8 linearly decrease to -U2; the voltages of piezoelectric wafers p3 - 3 and r3 - 5 linearly increase from 0 to U3, and the voltages of piezoelectric wafers q3 - 4 and s3 - 6 linearly decrease from 0 to -U3; under the action of the inverse piezoelectric effect, piezoelectric wafers n3 - 1, u3 - 7, p3 - 3, and r3 - 5 gradually elongate, and piezoelectric wafers o3 - 2, w3 - 8, q3 - 4, and s3 - 6 gradually shorten. Since the maximum static frictions between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units A1 and B2 are in a static state. Therefore, the maximum reverse static friction exerted by the ground on the driving feet 11 in nested unit C3 is less than the sum of the maximum forward frictions exerted by the ground on the driving feet 11 in nested units A1 and B2. Thus, the center of the positioning platform is stationary, and the two plate - type flexible hinges II 21 in nested unit C3 bend, driving the driving end II 23 in nested unit C3 to generate a displacement t2. At the same time, the two plate - type flexible hinges I 14 in nested unit C3 bend, driving the entire inner driving mechanism 10 in nested unit C3 to generate a displacement t1. Under the synthesis of displacement t1 and displacement t2, the driving feet 11 in nested unit C3 displace from point c to point c1;

[0078] 4. During the process of 3T / 4 - T, the voltages of all piezoelectric wafers linearly increase / decrease to 0. Since there are static frictions between the driving feet 11 in the three nested units and the ground, the three driving feet 11 are stationary, and the center of the positioning platform displaces by t, from point d to point d1.

[0079] If the above process is continuously repeated, the positioning platform can achieve a large - stroke stepping linear displacement output along the positive X - axis; by changing the voltage direction, a large - stroke stepping linear displacement output along the negative X - axis can be achieved, which will not be elaborated here.

[0080] Refer to Figures 1 - 8 and Figure 10 、 Figure 12 , taking the output of a stepping linear displacement along the positive Y - axis as an example, the specific process is as follows:

[0081] Apply Figure 12 type - I signals in e to piezoelectric wafers G1 - 4 and I1 - 6 simultaneously, and apply Figure 12 type - II signals in e to piezoelectric wafers F1 - 3 and H1 - 5 simultaneously; apply Figure 12 type - I signals in f to piezoelectric wafers q3 - 4 and s3 - 6 simultaneously, and apply to piezoelectric wafers p3 - 3 and r3 - 5 simultaneouslyFigure 12 Type II signal in f; Apply simultaneously to piezoelectric wafer n3-1 and piezoelectric wafer u3-7 Figure 12 Type I signal in g; Apply simultaneously to piezoelectric wafer o3-2 and piezoelectric wafer w3-8 Figure 12 Type II signal in g; Apply simultaneously to piezoelectric wafer M2-2 and piezoelectric wafer S2-8 Figure 12 Type I signal in h; Apply simultaneously to piezoelectric wafer L2-1 and piezoelectric wafer R2-7 Figure 12 Type II signal in h; Apply simultaneously to piezoelectric wafer O2-4 and piezoelectric wafer Q2-6 Figure 12 Type I signal in i; Apply simultaneously to piezoelectric wafer N2-3 and piezoelectric wafer P2-5 Figure 12 Type II signal in i;

[0082] 1. During the period from 0 to T / 4, the voltages of piezoelectric wafers G1-4 and I1-6 increase linearly from 0 to U1, and the voltages of piezoelectric wafers F1-3 and H1-5 decrease linearly from 0 to -U1; under the action of the inverse piezoelectric effect, piezoelectric wafers G1-4 and I1-6 gradually elongate, and piezoelectric wafers F1-3 and H1-5 gradually shorten. Since the maximum static friction forces of the driving feet 11 on the ground and in the three nested units are equal, the driving feet 11 in the nested units B2 and C3 are in a static state. Therefore, the maximum reverse static friction force exerted by the ground on the driving feet 11 in the nested unit A1 is less than the sum of the maximum forward friction forces exerted by the ground on the driving feet 11 in the nested units B2 and C3. Thus, the center of the positioning platform is stationary, and the two plate-type flexible hinges I14 in the nested unit A1 bend, driving the entire inner driving mechanism 10 in the nested unit A1 to generate a displacement t. As a result, the driving feet 11 in the nested unit A1 are displaced from point a to point a2;

[0083] 2. During the process from T / 4 to T / 2, the voltages of piezoelectric wafers q3-4 and s3-6 linearly increase from 0 to U2, and the voltages of piezoelectric wafers p3-3 and r3-5 linearly decrease from 0 to -U2; the voltages of piezoelectric wafers n3-1 and u3-7 linearly increase from 0 to U3, and the voltages of piezoelectric wafers o3-2 and w3-8 linearly decrease from 0 to -U3; under the action of the inverse piezoelectric effect, piezoelectric wafers q3-4, s3-6, n3-1, and u3-7 gradually elongate, and piezoelectric wafers p3-3, r3-5, o3-2, and w3-8 gradually shorten. Since the maximum static friction forces between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units A1 and B2 are in a static state. Therefore, at this time, the maximum reverse static friction force exerted by the ground on the driving feet 11 in nested unit C3 is less than the sum of the maximum forward friction forces exerted by the ground on the driving feet 11 in nested units A1 and B2. Thus, the center of the positioning platform is stationary, and the two plate-shaped flexible hinges II 21 in nested unit C3 bend, driving the driving end II 23 in nested unit C3 to generate a displacement t1. At the same time, the two plate-shaped flexible hinges I 14 in nested unit C3 bend, driving the entire inner driving mechanism 10 in nested unit C3 to generate a displacement t2. Under the synthesis of displacement t1 and displacement t2, the driving feet 11 in nested unit C3 displace from point c to point c2;

[0084] 3. During the process from T / 2 to 3T / 4, the voltages of piezoelectric wafers M2-2 and S2-8 linearly increase from 0 to U2, and the voltages of piezoelectric wafers L2-1 and R2-7 linearly decrease to -U2; the voltages of piezoelectric wafers O2-4 and Q2-6 linearly increase from 0 to U3, and the voltages of piezoelectric wafers N2-3 and P2-5 linearly decrease from 0 to -U3; under the action of the inverse piezoelectric effect, piezoelectric wafers M2-2, S2-8, O2-4, and Q2-6 gradually elongate, and piezoelectric wafers L2-1, R2-7, N2-3, and P2-5 gradually shorten. Since the maximum static friction forces between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units A1 and C3 are in a static state. Therefore, at this time, the maximum reverse static friction force exerted by the ground on the driving feet 11 in nested unit B2 is less than the sum of the maximum forward friction forces exerted by the ground on the driving feet 11 in nested units A1 and C3. Thus, the center of the positioning platform is stationary, and the two plate-shaped flexible hinges II 21 in nested unit B2 bend, driving the driving end II 23 in nested unit B2 to generate a displacement t1. At the same time, the two plate-shaped flexible hinges I 14 in nested unit B2 bend, driving the entire inner driving mechanism 10 in nested unit B2 to generate a displacement t2. Under the synthesis of displacement t1 and displacement t2, the driving feet 11 in nested unit B2 displace from point b to point b2;

[0085] 4. During the 3T / 4-T process, the voltages of all piezoelectric wafers linearly rise / fall to 0. Since there is static friction between the driving feet 11 and the ground in the three nested units, the three driving feet 11 are stationary, and the center displacement t of the positioning platform moves from point d to point d2.

[0086] If the above process is continuously repeated, the positioning platform can achieve a large-stroke stepping linear displacement output in the positive Y-axis direction; by changing the voltage direction, a large-stroke stepping linear displacement output in the negative Y-axis direction can be achieved, which will not be elaborated here.

[0087] Within one cycle, by controlling the voltage magnitudes of the excitation signals received by the piezoelectric wafers in each nested unit, the excitation sequence can, based on the friction difference and displacement synthesis, cause the three driving feet to each generate the same displacement at any position on their respective trajectory circles in the plane, and then drive the entire positioning platform to perform corresponding displacements. If the above process is continuously repeated, the positioning platform can achieve omnidirectional displacement in the plane.

[0088] Refer to Figures 1 - 8 and Figure 11 、 Figure 13 , the specific process of the clockwise rotational displacement output of the present invention about the Z-axis is as follows:

[0089] Simultaneously apply Figure 13 type I signals in j to piezoelectric wafers G1-4 and piezoelectric wafers I1-6, and simultaneously apply Figure 13 type II signals in j to piezoelectric wafers F1-3 and piezoelectric wafers H1-5; simultaneously apply Figure 13 type I signals in k to piezoelectric wafers o3-2 and piezoelectric wafers w3-8, and simultaneously apply Figure 13 type II signals in k to piezoelectric wafers n3-1 and piezoelectric wafers u3-7; simultaneously apply Figure 13 type I signals in m to piezoelectric wafers N2-3 and piezoelectric wafers P2-5, and simultaneously apply Figure 13 type II signals in m to piezoelectric wafers O2-4 and piezoelectric wafers Q2-6;

[0090] 1. During the process from 0 to T / 4, the voltages of piezoelectric wafers G1-4 and I1-6 linearly increase from 0 to U1, and the voltages of piezoelectric wafers F1-3 and H1-5 linearly decrease from 0 to -U1. Under the action of the inverse piezoelectric effect, piezoelectric wafers G1-4 and I1-6 gradually elongate, and piezoelectric wafers F1-3 and H1-5 gradually shorten. Since the maximum static friction forces between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units B2 and C3 are in a static state. Therefore, the maximum reverse static friction force exerted by the ground on the driving foot 11 in nested unit A1 is less than the sum of the maximum forward friction forces exerted by the ground on the driving feet 11 in nested units B2 and C3. Thus, the center of the positioning platform is stationary, and the two plate-type flexible hinges Ⅰ14 in nested unit A1 bend, driving the entire inner driving mechanism 10 in nested unit A1 to generate a displacement t. As a result, the driving foot 11 in nested unit A1 moves from point a to point a3;

[0091] 2. During the process from T / 4 to T / 2, the voltages of piezoelectric wafers o3-2 and w3-8 linearly increase from 0 to U1, and the voltages of piezoelectric wafers n3-1 and u3-7 linearly decrease from 0 to -U1. Under the action of the inverse piezoelectric effect, piezoelectric wafers o3-2 and w3-8 gradually elongate, and piezoelectric wafers n3-1 and u3-7 gradually shorten. Since the maximum static friction forces between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units B2 and A1 are in a static state. Therefore, the maximum reverse static friction force exerted by the ground on the driving foot 11 in nested unit C3 is less than the sum of the maximum forward friction forces exerted by the ground on the driving feet 11 in nested units B2 and A1. Thus, the center of the positioning platform is stationary, and the two plate-type flexible hinges Ⅰ14 in nested unit C3 bend, driving the entire inner driving mechanism 10 in nested unit C3 to generate a displacement t. As a result, the driving foot 11 in nested unit C3 moves from point c to point c3;

[0092] 3. During the process from T / 2 to 3T / 4, the voltages of piezoelectric wafers N2-3 and P2-5 linearly increase from 0 to U1, and the voltages of piezoelectric wafers O2-4 and Q2-6 linearly decrease from 0 to -U1; under the action of the inverse piezoelectric effect, piezoelectric wafers N2-3 and P2-5 gradually elongate, and piezoelectric wafers O2-4 and Q2-6 gradually shorten. Since the maximum static frictions between the ground and the driving feet 11 in the three nested units are equal, the driving feet 11 in nested units C3 and A1 are in a static state. Therefore, the maximum reverse static friction exerted by the ground on the driving feet 11 in nested unit B2 is less than the sum of the maximum forward frictions exerted by the ground on the driving feet 11 in nested units C3 and A1. Thus, the center of the positioning platform is stationary, and the two plate-type flexible hinges Ⅰ14 in nested unit B2 bend, driving the entire internal driving mechanism 10 in nested unit B2 to generate a displacement t. As a result, the driving feet 11 in nested unit B2 are displaced from point b to point b3.

[0093] 4. During the process from 3T / 4 to T, the voltages of all piezoelectric wafers linearly increase / decrease to 0. Since there are static frictions between the driving feet 11 in the three nested units and the ground, the positioning platform rotates around the Z-axis by an angle Φ. At the same time, the three driving feet are displaced by W along the Z-axis under the action of the plate-type flexible hinge Ⅰ14 and the plate-type flexible hinge Ⅱ21. The three driving feet 11 are respectively displaced from point a3 to point a4, from point b3 to point b4, and from point c3 to point c4, completing one rotation displacement output.

[0094] If the above process is continuously repeated, the positioning platform can achieve a large-stroke stepwise rotational displacement output in the clockwise direction around the Z-axis; by changing the voltage direction, a large-stroke stepwise rotational displacement output in the counterclockwise direction around the Z-axis can be achieved, which will not be elaborated here.

[0095] The above embodiments 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 foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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 bionic step planar universal piezoelectric positioning platform based on differential friction drive, characterized in that: It includes a nested unit A (1), a nested unit B (2), a nested unit C (3) and a connecting seat (5); The nested unit A (1), the nested unit B (2) and the nested unit C (3) have the same structure, and the three nested units are evenly distributed on the same circumference; The nested unit C (3) includes four pairs of piezoelectric wafers (8), an outer driving mechanism (7), an inner driving mechanism (10) and driving feet (11); The outer driving mechanism (7) includes a driving end Ⅰ (13), two plate-shaped flexible hinges Ⅰ (14), a support seat (16) and a connecting platform Ⅰ (18). The support seat (16) is provided with a rectangular through hole (15). The first ends of the two plate-shaped flexible hinges Ⅰ (14) are respectively fixedly connected to both sides of the driving end Ⅰ (13), the second ends of the two plate-shaped flexible hinges Ⅰ (14) are respectively fixedly connected to both sides of the support seat (16), and the connecting platform Ⅰ (18) is connected to the support seat (16); The inner driving mechanism (10) includes a connecting platform Ⅱ (20), two plate-shaped flexible hinges Ⅱ (21) and a driving end Ⅱ (23). The second ends of the two plate-shaped flexible hinges Ⅱ (21) are respectively fixedly connected to both sides of the driving end Ⅱ (23), the first ends of the two plate-shaped flexible hinges Ⅱ (21) are respectively fixedly connected to both sides of the connecting platform Ⅱ (20). The upper end of the outer driving mechanism (7) and the upper end of the inner driving mechanism (10) are fixedly connected. A fastening threaded hole Ⅱ (22) is opened at the center of the driving end Ⅱ (23); The driving feet (11) are installed in the fastening threaded hole Ⅱ (22); Piezoelectric wafers (8) are adhesively bonded to both sides of the two plate-shaped flexible hinges Ⅰ (14) and the two plate-shaped flexible hinges Ⅱ (21); By controlling the sequential excitation of the piezoelectric wafers by voltage, the inner driving mechanism (10) and the outer driving mechanism (7) in the three nested units generate sequential deformations, so that the driving feet (11) generate sequential displacements under the action of the friction difference, thereby realizing the universal stepping displacement output of the positioning platform in the plane and the stepping rotation displacement output around its own central axis.

2. The bionic stepping planar universal piezoelectric positioning platform based on differential friction drive according to claim 1, wherein: The connecting seat (5) includes a base (26) and three connecting platforms Ⅲ (24). The base (26) is provided with a central hole (27) and three through holes Ⅱ (28). The three through holes Ⅱ (28) are evenly distributed in a circular shape outside the central hole (27). The central hole (27) and the three through holes Ⅱ (28) are used for installing a loading platform later. The three connecting platforms Ⅲ (24) are evenly distributed on the same circumference and fixedly connected to the base (26). Two fastening threaded holes Ⅲ (25) are opened on each of the three connecting platforms Ⅲ (24) for connecting the nested unit A (1), the nested unit B (2) and the nested unit C (3).

3. The bionic step planar universal piezoelectric positioning platform based on differential friction drive according to claim 2, wherein: A rectangular through slot is opened on the driving end Ⅰ (13), and two through holes Ⅰ (12) are provided on the driving end Ⅰ (13). A rectangular through slot is opened on the connecting platform Ⅱ (20), and two fastening threaded holes Ⅰ (19) corresponding to the through holes Ⅰ (12) are machined on the connecting platform Ⅱ (20). Two fastening bolts Ⅱ (6) respectively pass through the through holes Ⅰ (12) and are installed in the fastening threaded holes Ⅰ (19), so that the upper surface of the rectangular through slot of the driving end Ⅰ (13) and the lower surface of the rectangular through slot of the connecting platform Ⅱ (20) are closely attached.

4. A bionic stepping planar universal piezoelectric positioning platform based on differential friction drive according to claim 3, characterized in that: The connecting platform I (18) is provided with two counterbored holes (17) corresponding to the fastening threaded holes III (25). Two fastening bolts I (4) respectively pass through the counterbored holes (17) and are installed in the fastening threaded holes III (25), thereby fixedly connecting the nested unit C (3) and the connecting seat (5).

5. The bionic stepping planar universal piezoelectric positioning platform based on differential friction drive according to claim 4, wherein: The nested unit C (3) further includes a fastening nut (9). A fastening nut (9) is threadedly connected to the driving foot (11). The driving foot (11) is a ceramic ball screw, and a ceramic ball is installed at the bottom of its screw.

6. The bionic stepping planar universal piezoelectric positioning platform based on differential friction drive according to claim 5, wherein: In the outer driving mechanism (7), the length and width of the rectangular through hole (15) are respectively greater than the length and width of the driving end II (23) in the inner driving mechanism (10), ensuring that the driving end II (23) in the inner driving mechanism (10) can displace within the rectangular through hole (15) of the outer driving mechanism (7).

7. The bionic stepping planar universal piezoelectric positioning platform based on differential friction drive according to claim 6, wherein: Both the outer driving mechanism (7) and the inner driving mechanism (10) are integrally machined from a single piece of elastic metal material.

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