Two-dimensional piezoelectric driving platform for suppressing orthogonal disturbance

Abstract

The application provides a two-dimensional piezoelectric driving platform for inhibiting orthogonal disturbance, which comprises a base plate and a working platform, four groups of flexible isolation structures are arranged in the X-Y orthogonal plane with the center of the working platform as the origin, the flexible isolation structures are connected with the working platform through a guide mechanism, piezoelectric driving units are arranged on the side away from the working platform of each group of orthogonal flexible isolation structures, the piezoelectric driving unit comprises a U-shaped groove, two piezoelectric stacks and a center block, the U-shaped groove is arranged on the base plate and connected with both ends of the flexible isolation structure, the center block is connected with the middle part of the outer side of the flexible isolation structure, the two ends of the piezoelectric stack are provided with ball heads, and the two ends of the piezoelectric stack are respectively in contact with the inner side wall of the U-shaped groove and the side surface of the center block. The application enhances the anti-disturbance ability of the piezoelectric driving unit through the flexible isolation structure, avoids the lateral force of the piezoelectric driving unit in the X(Y) direction on the piezoelectric driving unit in the Y(X) direction when the piezoelectric driving unit in the X(Y) direction works, and causes the piezoelectric driving unit to deflect and not work normally.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of two-dimensional piezoelectric driving platform in parallel, and particularly relates to a two-dimensional piezoelectric driving platform for suppressing orthogonal disturbance. BACKGROUND

[0002] In the field of aerial imaging, due to the large relative speed between the imaging system and the target, and the vibration of the aircraft itself, the imaging is blurred. At present, the clear and stable imaging of the imaging system can be realized by adjusting the boresight of the optical lens in the optical system through the piezoelectric driving platform.

[0003] Document [Optical Precision Engineering, 2017, 25(6): 1494-1501] discloses a two-way actuation large-stroke two-degree-of-freedom image stabilization mechanism, which connects two-direction piezoelectric driving units to the working platform through flexible hinges, and realizes arbitrary movement in the plane by synthesizing the displacement outputs in two perpendicular directions. However, as can be seen from the deformation diagram of the two-dimensional mechanism, the movement in one direction will cause the piezoelectric driving unit in the other direction to deform severely, which cannot work normally, and even damage the piezoelectric stack.

[0004] The above-mentioned traditional two-dimensional piezoelectric driving platform has the following disadvantages:

[0005] I. The driving stroke of the driving platform changes greatly with the change of the load stiffness, and the output stability is poor.

[0006] II. There is orthogonal disturbance between the piezoelectric driving units, that is, when the piezoelectric driving unit in one direction drives the working platform, the working platform will apply a lateral force to the piezoelectric driving unit in the orthogonal direction through the guide mechanism, causing the unit to deflect, and even causing the internal piezoelectric stack to be damaged.

[0007] Therefore, the purpose of the present application is to improve the displacement output stability and the anti-orthogonal disturbance ability of the two-dimensional piezoelectric driving platform. SUMMARY

[0008] The purpose of the present application is to provide a two-dimensional piezoelectric driving platform for suppressing orthogonal disturbance, which can realize anti-orthogonal disturbance and stable output displacement, and solve the problems of small output stiffness of the traditional parallel piezoelectric actuator, easy influence of the stroke by the load change, and orthogonal disturbance between the piezoelectric driving units.

[0009] The application provides a two-dimensional piezoelectric driving platform for inhibiting orthogonal disturbance, which comprises a substrate and a working platform arranged in the middle of the substrate, four groups of flexible isolation structures symmetrically arranged with respect to an X axis and a Y axis in an X-Y orthogonal plane with the center of the working platform as the origin, guiding mechanisms connecting the edges of the working platform and the flexible isolation structures, piezoelectric driving units arranged on the side away from the working platform of the two groups of flexible isolation structures at one end of the X axis and the Y axis, a U-shaped groove, two piezoelectric stacks and a center block, the U-shaped groove is arranged on the substrate and connected to the two ends of the flexible isolation structure, the inner side wall of the U-shaped groove is concave, the center block is connected to the middle part of the outer side of the flexible isolation structure, the two sides of the center block are concave, and the two ends of the piezoelectric stack are provided with ball heads and are in contact with the inner side wall of the U-shaped groove and the side surface of the center block respectively.

[0010] Preferably, the flexible isolation structure is a flexible isolation beam, and the flexible isolation beam is a thin plate beam fixedly connected to the substrate at both ends.

[0011] Preferably, the surface of the flexible isolation beam is parallel to the side surface of the working platform, and the two ends of the guiding mechanism are fixedly connected to the working platform and the flexible isolation beam respectively.

[0012] Preferably, the guiding mechanism is two mutually parallel guiding plates, and the two ends of the guiding plates are vertically connected to the side surface of the working platform and the flexible isolation beam respectively.

[0013] Preferably, the working platform is a square platform arranged in the middle of the substrate, the outer periphery of the working platform is separated from the substrate by an isolation groove, and a circular mounting groove is arranged in the center of the working platform.

[0014] Preferably, a fixing hole is arranged at each corner of the substrate.

[0015] Preferably, the inner side wall of the U-shaped groove is concave into a circular arc surface, and the two side surfaces of the center block are concave into circular arc surfaces.

[0016] Preferably, the two ends of the piezoelectric stack are in interference fit with the inner side wall of the U-shaped groove and the side surface of the center block.

[0017] Preferably, the guiding plate is an elastic plate member which can be bent and deformed when the working platform moves.

[0018] Preferably, the two piezoelectric stacks of the same piezoelectric driving unit apply voltages of the same size and direction.

[0019] The technical scheme of the present application enhances the anti-disturbance capability of the piezoelectric driving unit through the flexible isolation structure, avoids the lateral force brought to the piezoelectric driving unit in the Y (X) direction when the piezoelectric driving unit in the X (Y) direction works, causes the piezoelectric driving unit to deflect and cannot work normally, ensures that both piezoelectric driving units can work normally at the same time, improves the output stiffness of the piezoelectric driving unit, the driving stroke is not easily affected by the change of the load stiffness, enhances the output stability of the two-dimensional piezoelectric driving platform, and is beneficial to the two-dimensional piezoelectric driving platform to meet the use requirements under different working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical scheme in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0021] Figure 1 is a top view of the two-dimensional piezoelectric driving platform of the present application;

[0022] Figure 2 is a perspective view of the two-dimensional piezoelectric driving platform of the present application;

[0023] Figure 3 is a top view of the piezoelectric driving unit in the present application;

[0024] Figure 4 is a structural schematic view of the flexible isolation beam in the present application.

[0025] Explanation of reference signs:

[0026] 1: base plate; 2: working platform; 3: flexible isolation beam; 4: guide mechanism; 5: U-shaped groove; 6: piezoelectric stack; 7: center block; 8: circular mounting groove; 9: fixing hole. DETAILED DESCRIPTION

[0027] The technical scheme of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements indicated thereby must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0029] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited. In addition, the terms "mounting", "connecting", "connecting" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] As shown in Figure 1 , 2 The present application provides a two-dimensional piezoelectric driving platform for suppressing orthogonal disturbance, which comprises a substrate 1 and a work platform 2 arranged in the middle of the substrate 1, the work platform 2 is square, and four groups of flexible isolation structures symmetric about the X-axis and the Y-axis are arranged in the X-Y orthogonal plane with the center of the work platform 2 as the origin, the flexible isolation structure is a flexible isolation beam 3, each flexible isolation beam 3 is connected to each side of the work platform 2 through a guide mechanism 4, and the two groups of flexible isolation beams 3 located at the ends of the X-axis and the Y-axis orthogonal to each other are respectively provided with a piezoelectric driving unit on the side away from the work platform 2.

[0031] In this embodiment, the work platform 2 is a square platform cut and separated from the middle of the substrate 1, and the outer periphery of the work platform 2 is separated from the body of the substrate 1 by an isolation groove, so that the work platform 2 can be moved along the X-Y plane under the action of the piezoelectric driving unit. A circular mounting groove 8 is formed in the center of the work platform 2, which can be used to mount a load. Fixed holes 9 are formed at each corner of the substrate 1, which can be used to fix the two-dimensional piezoelectric driving platform.

[0032] As shown in Figure 3As shown, the piezoelectric driving unit comprises a U-shaped groove 5, two piezoelectric stacks 6 and a center block 7, wherein the U-shaped groove 5 is formed on the substrate 1 and connected with the two ends of the flexible isolation beam 3, the inner side wall of the U-shaped groove 5 is concave into a circular arc surface, the center block 7 is connected with the middle part of the side of the flexible isolation beam 3 away from the workbench 2, the center block 7 extends into the U-shaped groove 5, and the axis of the center block 7 is collinear with the axis of the U-shaped groove 5, the two sides of the center block 7 are concave into circular arc surfaces, the two ends of the piezoelectric stack 6 are provided with ball heads, the two ends of the two piezoelectric stacks 6 are respectively in contact with the inner side wall of the U-shaped groove 5 and the side of the center block 7, the two ends of the piezoelectric stack 6 are in interference fit with the inner side wall of the U-shaped groove 5 and the side of the center block 7, and the angle between the axis of the piezoelectric stack 6 and the bottom of the U-shaped groove 5 is θ, and through the cooperation of the ball head and the circular arc surface, the damage of the piezoelectric stack 6 caused by the introduction of lateral force during the movement of the center block 7 can be avoided.

[0033] In the embodiment, the flexible isolation beam 3 is a thin plate beam fixedly connected with the substrate 1 at both ends. The surface of the flexible isolation beam 3 is parallel to the side surface of the workbench 2, and the two ends of the guide mechanism 4 are fixedly connected with the workbench 2 and the flexible isolation beam 3 respectively. The guide mechanism 4 is two mutually parallel guide plates, the two ends of the guide plates are respectively connected with the side surfaces of the workbench 2 and the flexible isolation beam 3 perpendicularly, and the guide plates are elastic plate members which can be bent and deformed when the workbench 2 moves.

[0034] Compared with the piezoelectric driver which uses the flexible deformation of the mechanism to amplify the displacement, the piezoelectric driving unit of the present application has no flexible part, has a large output stiffness, and the driving stroke is not easily affected by the change of the load stiffness. The flexible isolation beam 3 is designed on the outside of the piezoelectric driving unit, which can isolate the disturbance in the orthogonal direction and protect the piezoelectric driving unit from deflecting due to the actuation in the orthogonal direction. The specific scheme is analyzed as follows:

[0035] I. When the piezoelectric driving unit works without load, the stroke can reach the designed maximum stroke x max ; when the piezoelectric driving unit drives the load to work, the stroke x is reduced due to the influence of the load stiffness K F , and the following equation is obtained:

[0036]

[0037] Wherein, K Q is the output stiffness of the piezoelectric driving unit.

[0038] As can be seen from the above equation, when the output stiffness of the piezoelectric driving unit is constant, the greater the stiffness of the load, the smaller the output displacement of the piezoelectric driving unit, and the greater the output stiffness of the piezoelectric driving unit, the smaller the influence of the change of the load stiffness on the output displacement of the piezoelectric driving unit.

[0039] Therefore, the application improves the output stability of the two-dimensional piezoelectric driving platform by improving the output stiffness of the piezoelectric driving unit.

[0040] II. When the piezoelectric driving unit is subjected to orthogonal disturbance, deflection occurs and the piezoelectric driving unit cannot work normally. A mechanism needs to be designed between the piezoelectric driving unit and the guide mechanism, which has a large stiffness in the lateral force direction to resist the lateral force and protect the piezoelectric driving unit from deflection caused by the lateral force, and has a small stiffness in the displacement output direction of the piezoelectric driving unit to minimize the weakening of the output displacement of the piezoelectric driving unit.

[0041] Based on the analysis, the application adds two symmetrical thin plate beams to form a flexible isolation beam 3 between the piezoelectric driving unit and the guide mechanism 4, which avoids the deflection of the piezoelectric driving unit caused by orthogonal disturbance.

[0042] Taking the Y direction displacement as an example, the same positive voltage is applied to the two piezoelectric stacks 6 of the piezoelectric driving unit in the Y axis, and the piezoelectric stacks 6 are elongated at the same time, and the displacement component in the vertical direction drives the output displacement of the center block. The angle between the piezoelectric stack 6 and the horizontal line is θ, the two piezoelectric stacks are elongated along the length direction at the same time, the center block 7 generates a vertical displacement A, according to the principle of triangular amplification, the displacement amplification ratio δ = 1 / tanθ, then the output displacement A of the piezoelectric driving unit is represented as:

[0043] A = a / tanθ

[0044] Wherein, a is the output displacement of the piezoelectric stack 6.

[0045] The center block 7 drives the work platform 2 to generate displacement through the guide mechanism 4 on the same side, and the movement of the work platform 2 causes the guide mechanism 4 in the orthogonal direction to deform, at this time, the isolation flexible beam 3 parallel to the displacement direction can isolate the above deformation and will not be transmitted to the piezoelectric driving unit on the same side, for example, the deformation caused by the displacement in the Y axis direction will not be transmitted to the piezoelectric driving unit in the X axis direction, avoiding causing the piezoelectric driving unit to deflect and cannot work normally.

[0046] In addition, the application also improves the output stiffness, the specific reasons are as follows:

[0047] The application uses two piezoelectric stacks 6 with ball heads to replace the flexible beams of the diamond mechanism based on the principle of triangular amplification, and designs a piezoelectric driving unit as shown in the figure. Figure 3 The piezoelectric driving unit has no flexible part. Through force analysis, the output stiffness is represented as follows:

[0048] K Q = 2*K PZT , sinθ*tanθ

[0049] Wherein, KPZT The rigidity of the piezoelectric stack 6, θ is the angle between the piezoelectric stack 6 and the horizontal line or the bottom surface of the U-shaped groove 5.

[0050] Taking K PZT = 60 N / μm, θ = 10°, the output rigidity K of the piezoelectric driving unit can be obtained Q = 3.67 N / μm, the output rigidity of the piezoelectric driver generally using a flexible amplification mechanism is in the order of 10- 2 N / μm.

[0051] Therefore, compared with the traditional flexible displacement amplification mechanism, the piezoelectric driving unit has very high output rigidity, and the output displacement of the two-dimensional piezoelectric driving platform is less affected by the change of load rigidity.

[0052] For the design goal of resisting orthogonal disturbance, the specific implementation is as follows:

[0053] As Figure 4 shown is a structural schematic diagram of a thin plate beam, and the structural parameters are length l, width t, and thickness b.

[0054] The tensile rigidity K l can be represented as

[0055]

[0056] The rotational rigidity K r can be represented as

[0057]

[0058] Taking t = 0.4 mm,

[0059]

[0060] It can be found that when the thickness t of the thin plate beam is 0.4 mm, the tensile rigidity is 37.5 times the rotational rigidity.

[0061] Therefore, the smaller rotational rigidity meets the design goal of avoiding weakening the driving stroke of the piezoelectric driving unit, and the larger tensile rigidity of the flexible isolation beam 3 resists the lateral force caused by the driving unit in the orthogonal direction, so as to achieve the design goal of resisting orthogonal disturbance.

[0062] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances, characterized in that, include: The substrate and a working platform located in its center have four sets of flexible isolation structures arranged symmetrically with respect to the X-axis and Y-axis in an XY orthogonal plane with the center of the working platform as the origin. These flexible isolation structures are connected to the edges of the working platform via guide mechanisms. Piezoelectric driving units are respectively arranged on the side of the two sets of flexible isolation structures located at one end of the X-axis and Y-axis, away from the working platform. Each piezoelectric driving unit includes a U-shaped groove, two piezoelectric stacks, and a central block. The U-shaped groove is formed on the substrate and connected to both ends of the flexible isolation structures. The inner wall of the U-shaped groove is concave, the central block is connected to the middle of the outer side of the flexible isolation structure, the two sides of the central block are concave, both ends of the piezoelectric stack are provided with ball heads, the two ends of the piezoelectric stack respectively abut against the inner wall of the U-shaped groove and the side of the central block, the flexible isolation structure is a flexible isolation beam, the flexible isolation beam is a thin plate beam whose two ends are fixedly connected to the substrate, the surface of the flexible isolation beam is parallel to the side of the working platform, and the two ends of the guide mechanism are fixedly connected to the working platform and the flexible isolation beam respectively.

2. The two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances according to claim 1, characterized in that, The guiding mechanism consists of two parallel guide plates, with both ends of the guide plates perpendicularly connected to the side of the working platform and the flexible isolation beam, respectively.

3. The two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances according to claim 1, characterized in that, The working platform is a square platform located in the middle of the substrate. The outer periphery of the working platform is separated from the substrate by an isolation groove, and a circular mounting groove is provided in the center of the working platform.

4. The two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances according to claim 1, characterized in that, Fixing holes are provided at each corner of the substrate.

5. The two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances according to claim 1, characterized in that, The inner wall of the U-shaped groove is concave into an arc surface, and the two sides of the central block are concave into arc surfaces.

6. The two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances according to claim 5, characterized in that, The two ends of the piezoelectric stack are interference-fitted with the inner sidewall of the U-shaped groove and the side of the central block.

7. The two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances according to claim 2, characterized in that, The guide plate is an elastic plate that can be bent and deformed when the working platform moves.

8. The two-dimensional piezoelectric drive platform for suppressing orthogonal disturbances according to claim 1, characterized in that, The magnitude and direction of the voltage applied to the two piezoelectric stacks of the same piezoelectric drive unit are the same.

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