Stacked triaxial piezoelectric flexible hinge platform

Abstract

The application provides a stacked three-axis piezoelectric flexible hinge platform, and belongs to the technical field of mechanical precision displacement driving. The hinge platform is a stacked structure along the Z direction, and sequentially comprises, from bottom to top, a main body provided with a Z-axis displacement unit, an X-axis displacement unit, a Y-axis displacement unit and an object table. The Z-axis displacement unit is installed in the main body, the main body has a fixed end and a moving end along the Z direction. The Z-axis displacement unit has a Z-axis output block at the top. The Z-axis output block is connected with the moving end of the main body. The moving end of the main body is provided with a first partition plate. An X-axis output block is installed on the first partition plate. The X-axis output block has a fixed end and a moving end along the X direction. The X-axis displacement unit is installed on the X-axis output block. A second partition plate is installed on the moving end of the X-axis output block. A Y-axis output block is installed on the second partition plate. The Y-axis output block has a fixed end and a moving end along the Y direction. The object table is connected with the moving end of the Y-axis output block.

Description

Technical Field

[0001] This invention relates to a hinge platform, specifically a stacked triaxial piezoelectric flexible hinge platform, belonging to the field of mechanical precision displacement drive technology. Background Technology

[0002] Piezoelectric ceramic stacked actuators, due to their nanometer-level resolution, millisecond-level response speed, and large output force, have become core actuation components in fields such as micro-nano positioning, optical alignment, biological microscopy imaging, and semiconductor detection. To further scale up the basic stroke of piezoelectric ceramics from tens of micrometers to hundreds of micrometers while simultaneously meeting the requirements of frictionless and gapless guidance, the field commonly employs a technical solution combining flexible hinge structures with displacement amplification mechanisms to form piezoelectric flexible hinge positioning platforms. When spatial three-dimensional positioning is required, existing technologies mainly adopt the following configuration approaches: Integrated multi-axis flexible hinge platform: This type of platform utilizes a continuous flexible hinge network formed by wire cutting from a single metal substrate (usually aluminum alloy or stainless steel). It integrates the XY (or XYZ) multi-axis motion guide structure, piezoelectric ceramic inserts, and pre-tensioning interfaces into a single unit. The advantages of this approach include zero assembly gaps, no frictional wear, uniform stiffness, and sub-nanometer resolution. However, the inherent characteristics of this integrated configuration mean that its three-axis (or multi-axis) motion functions share the same flexible deformation field and the same substrate. If a piezoelectric stack fractures due to fatigue or a localized flexible hinge area experiences plastic deformation / cracks, the entire machine typically needs to be removed from the optical path or equipment and returned to the factory for repair. Independent disassembly and replacement at the single-axis module level is not possible. Furthermore, the geometric parameters of the amplification mechanism and hinge network in this integrated topology are "fixed" after machining, making it difficult to adjust the stiffness matching and stroke distribution of different axes on-site as needed. In addition, the installation of piezoelectric ceramics in integral structures is mostly done by "groove tightening" or single-sided pre-tightening, which has limited precision adjustability of the pre-tightening force. Under long-term thermal cycling or dynamic loads, there is still a risk that the piezoelectric layer will be subjected to unexpected tensile / bending stress.

[0003] Series-Stacked Triaxial Flexible Platform: The common approach for existing series-stacked triaxial flexible platforms is to stack the X-axis platform on top of the Y-axis platform, and then connect the Z-axis platform (or Z-axis actuator) in series at the bottom or top, forming a three-layer series-stacked architecture. In this type of scheme, the motion of the upper platform is entirely borne by the lower platform, and the kinematic chain is in a cantilevered series relationship: not only do the lower axes (especially the bottom Z-axis bearing layer) have to bear the self-weight and eccentric load of all the modules above, resulting in a decrease in stiffness with the number of stacked layers, and an increase in modal coupling and "parasitic motion" with the increase of load; moreover, the axes usually share the same base or the same set of main load-bearing interfaces. When the piezoelectric actuator or flexible hinge branch of a certain axis (especially the middle Y-axis or the bottom Z-axis) fails, it is still necessary to disassemble all the modules above layer by layer to reach the fault point, and the maintenance path is not truly shortened. In addition, in order to accommodate the light transmission aperture or wiring space of each layer, this type of tandem stacked structure often requires large-area cutouts on the flexible arm or the use of thin cantilever arms, which further weakens the resistance to lateral loads and long-term reliability.

[0004] In summary, the existing technology has the following main drawbacks and shortcomings: (1) Although the integral flexible hinge platform has excellent precision and rigidity, its single, non-modular, integrated topology means that it does not have the ability to be independently disassembled and replaced on a single axis. Once the piezoelectric ceramic actuator is damaged (cracked, insulation breakdown, performance drift) or the flexible hinge is locally fatigued, it often means that the whole machine is out of service and high-cost repairs, and the maintenance cost throughout the entire life cycle remains high.

[0005] (2) Although the existing series-stacked platform is nominally arranged in a “layered” manner, the kinematic chain is a cantilevered series bearing relationship. The upper layer motion introduces additional bending moments and parasitic displacements into the lower layer. The effective stiffness deteriorates with the number of stacked layers, and the dynamic coupling between axes is difficult to completely eliminate by the structure alone. Moreover, fault repair still requires disassembly layer by layer, which does not fundamentally solve the “maintainability layer problem”.

[0006] (3) The pre-tightening protection design of piezoelectric stacks in the existing schemes is generally insufficient: the integrated structure mostly adopts fixed block / groove surface contact limit, and the pre-tightening force is fixed after leaving the factory, making it difficult to re-inspect and fine-tune according to the actual state of the piezoelectric ceramic at the site; while the existing series structure superimposes the pre-tightening load to the lower bearing flexible arm, which increases the composite stress state of the hinge area, which is not conducive to the long-term survival of the piezoelectric ceramic.

[0007] (4) In the trade-off between “compact and small structure” and “large output displacement”, existing solutions often lose one thing: the integral solution has to constrain the amplification ratio to ensure stiffness, thus limiting the stroke, or introduce multiple amplification stages to expand the volume; the existing series solution compresses the flexible arm section to control the volume, thus sacrificing the load-bearing stiffness and motion straightness. Summary of the Invention

[0008] In view of this, the present invention provides a stacked triaxial piezoelectric flexible hinge platform, which can realize independent disassembly and replacement of any single axis through an orthogonally stacked modular architecture to significantly reduce maintenance downtime. It can also balance large output displacement, high rigidity and safe service life of piezoelectric ceramics through independently integrated displacement amplification mechanism and adjustable preload protection mechanism for each axis, while maintaining a compact overall shape and suitable for integration in space-constrained occasions.

[0009] The technical solution of the present invention is: a stacked triaxial piezoelectric flexible hinge platform, wherein the hinge platform is a stacked structure along the Z direction, and from bottom to top, it consists of: a main body with a Z-axis displacement unit, an X-axis displacement unit, a Y-axis displacement unit, and a stage; The Z-axis displacement unit, X-axis displacement unit and Y-axis displacement unit are all piezoelectric flexible hinge positioning platforms; The Z-axis displacement unit is installed inside the main body, which has a fixed end and a moving end along the Z direction; the top of the Z-axis displacement unit has a Z-axis output block; the Z-axis output block is connected to the moving end of the main body; the moving end of the main body is equipped with a first partition. The X-axis output block is mounted on the first partition; the X-axis output block has a fixed end and a movable end along the X direction; the X-axis displacement unit is mounted on the X-axis output block, and one end of the X-axis displacement unit is connected to the fixed end of the X-axis output block, and the other end is connected to the movable end of the X-axis output block. The second partition is installed on the moving end of the X-axis output block; the Y-axis output block is installed on the second partition; the Y-axis output block has a fixed end and a moving end along the Y direction; the Y-axis displacement unit is installed on the Y-axis output block, wherein one end of the Y-axis displacement unit is connected to the fixed end of the Y-axis output block and the other end is connected to the moving end of the Y-axis output block at both ends in the Y direction. The stage is connected to the moving end of the Y-axis output block.

[0010] As a preferred embodiment of the present invention, a shallow groove is reserved on the surface of the Z-axis output block at the top of the Z-axis displacement unit for placing the Z-axis preload assembly. The Z-axis preload assembly includes a tapered tail cap and a screw plug; the lower end of the tapered tail cap is located in a shallow groove on the surface of the Z-axis output block, and the upper end passes through a hole on the top plate of the main body and is screwed to the screw plug, which is used to connect the Z-axis output block to the moving end of the main body. The lower end of the screw plug is hemispherical and adaptively coaxial with the conical tail cap.

[0011] In a preferred embodiment of the present invention, the top plate of the main body is its movable end, and the top plate is connected to the outer frame of the main body by flexible hinges around its perimeter, thereby realizing the movement of the top plate relative to the outer frame.

[0012] In a preferred embodiment of the present invention, the Z-axis displacement unit includes: a Z-axis piezoelectric drive assembly and a Z-axis triangular amplification mechanism; The Z-axis triangular amplification mechanism includes: a base and a flexible hinge arm; the Z-axis piezoelectric drive assembly is disposed in the piezoelectric ceramic mounting groove in the central region of the base and is connected to the connecting parts at both ends of the mounting groove. A flexible hinge arm is provided at each of the two opposite ends of the Z-axis piezoelectric drive assembly. The top center of the Z-axis displacement unit is provided with a vertical flexible hinge as a Z-axis output block; the bottom center is provided with a vertical flexible hinge for connecting the main body, and the main body is fixed.

[0013] In a preferred embodiment of the present invention, the X-axis displacement unit includes an X-axis piezoelectric drive assembly and an X-axis delta amplification mechanism; the X-axis piezoelectric drive assembly is placed in a piezoelectric ceramic mounting groove inside the X-axis delta amplification mechanism; one end of the X-axis delta amplification mechanism is connected to the moving end of the X-axis output block, and the other end is connected to the fixed end of the X-axis output block. The Y-axis displacement unit includes a Y-axis piezoelectric drive assembly and a Y-axis delta amplification mechanism. The Y-axis piezoelectric drive assembly is placed in a piezoelectric ceramic mounting slot inside the Y-axis delta amplification mechanism. At both ends of the Y-axis delta amplification mechanism, one end is connected to the moving end of the Y-axis output block, and the other end is connected to the fixed end of the Y-axis output block.

[0014] In a preferred embodiment of the present invention, the outer frame of the X-axis output block is its fixed end, which is mounted on the first partition; the middle part is its movable end, and its fixed end is connected to the output end by a flexible hinge. The outer frame of the Y-axis output block is its fixed end, which is mounted on the second partition; the middle part is its movable end, and its fixed end is connected to the output end by a flexible hinge.

[0015] In a preferred embodiment of the present invention, the flexible hinge between the fixed end and the output end of the X-axis output block is a loop-shaped symmetrical distribution structure. In the Y-axis output block, the flexible hinge between its fixed end and output end has a loop-shaped symmetrical distribution structure.

[0016] As a preferred embodiment of the present invention, the X-axis displacement unit and the Y-axis displacement unit are used in conjunction with the slide table to press the slide table and self-pre-tighten by the stiffness of the flexible hinge arm of the triangular amplification mechanism. For the X-axis displacement unit: Before installing the X-axis piezoelectric drive assembly, connect a slide table to each end of the X-axis delta amplification mechanism in the X direction. The two oppositely positioned slide tables move towards each other in the X direction, squeezing their flexible hinge arms to apply pressure. After squeezing, the piezoelectric ceramic mounting groove in the middle is opened. Then, install the X-axis piezoelectric drive assembly and fill it with glue. After the glue cures, restore the X-axis delta amplification mechanism to its initial position. At this time, the piezoelectric ceramic mounting groove in the middle is squeezed inward and shrinks, completing the pre-tightening. The Y-axis displacement unit adopts the same preload method as the X-axis displacement unit.

[0017] In a preferred embodiment of the present invention, an SGS strain gauge A is bonded to the moving end surface of the main body for measuring and feedback of Z-direction displacement. The weak resistance signal generated by the SGS strain gauge A is amplified by the sensing servo unit and then converted into a digital signal by a high-precision analog-to-digital converter circuit and input to the main control unit. The main control unit compares the actual measured real-time displacement with the externally input ideal target displacement value. After processing by the PID algorithm, it outputs the control quantity to the power amplifier module to drive the Z-axis displacement unit for dynamic compensation.

[0018] As a preferred embodiment of the present invention, SGS strain gauges B are attached to the flexible hinge deformation points of the X-axis output block and the Y-axis output block for displacement measurement and feedback. The weak resistance signal generated by the SGS strain gauge B is amplified by the sensing servo unit and then converted into a digital signal by a high-precision analog-to-digital converter circuit and input to the main control unit. The main control unit compares the actual measured real-time displacement with the externally input ideal target displacement value. After processing by the PID algorithm, it outputs the control quantity to the power amplifier module to drive the X-axis displacement unit and the Y-axis displacement unit to perform dynamic compensation.

[0019] Beneficial effects: (1) This invention breaks away from the traditional integral or serial configuration and designs the XYZ three axes as physically independent, functionally complete and quickly disassembled standardized modules (i.e., Z-axis displacement unit, X-axis displacement module and Y-axis displacement module), thereby solving the industry pain point of needing to repair the whole machine and the extremely high downtime maintenance cost when a single axis failure occurs. It enables the independent replacement of any faulty axis unit in situ without disassembling the other normal axis systems. Moreover, since only the Z-axis displacement unit is installed inside the main body, the X-axis displacement unit, Y-axis displacement unit and the stage are stacked on top of the main body and separated by partitions. Therefore, when in use, it is convenient to change the platform into any two-axis piezoelectric flexible hinge platform or any single-axis piezoelectric flexible hinge platform as needed.

[0020] (2) This invention can significantly improve the output displacement capability of the platform and optimize its size while ensuring high precision. By deeply integrating a high-efficiency displacement amplification mechanism and a flexible hinge (as a guiding mechanism) inside each independent axis module, the platform can effectively amplify the micro-displacement of piezoelectric ceramics to the level of hundreds of micrometers while maintaining a compact overall structure (i.e., thin and small in size). This overcomes the contradiction that existing compact designs cannot take into account large stroke output due to size limitations, and meets the dual requirements of large-area scanning and precise positioning in micro-nano operations. (3) The present invention constructs a complete piezoelectric ceramic drive protection mechanism: In view of the brittle behavior of piezoelectric ceramic materials that are resistant to compression but not to tension, a special pre-tightening mechanism is designed for each axis module, which can provide continuous, stable and adjustable pre-pressure for the piezoelectric ceramic stack, ensuring that the piezoelectric drive component is always in a safe pressure state during working cycle, assembly and accidental impact, effectively suppressing the damage of tensile stress and lateral shear force to the piezoelectric layer, thereby significantly extending the service life of the core drive component and improving the long-term reliability of the platform under complex working conditions.

[0021] (4) The present invention eliminates or weakens the motion coupling between axes by orthogonal stacking layout, ensuring the geometric orthogonality of each module during stacking assembly, so that the XYZ three-axis motion is strictly decoupled in space, reducing the complexity of motion control algorithm; the mounting holes (screw holes for detachable connection) on each component are strictly assembled according to the design dimensions, ensuring that the platform can still quickly restore the original high-precision positioning reference after multiple disassembly and maintenance, reducing the time cost of repeated assembly and adjustment. Attached Figure Description

[0022] Figure 1 This is an isometric view of the stacked triaxial piezoelectric flexible hinge platform of the present invention; Figure 2 This is an exploded view of the stacked triaxial piezoelectric flexible hinge platform of the present invention; Figure 3 This is a schematic diagram of the output principle of the Z-axis displacement unit; Figure 4 This is a schematic diagram of the output principle of the X-axis displacement unit; Figure 5 This is a schematic diagram of the assembly of the Z-axis displacement unit on the main body in this invention; Figure 6 This is a schematic diagram of the assembly of the X-axis displacement unit and the X-axis output block in this invention; Figure 7 This is a schematic diagram of the assembly of the Y-axis displacement unit and the Y-axis output block in this invention; Figure 8 This is a schematic diagram of the pre-tightening principle of the Z-axis displacement unit in this invention; Figure 9This is a schematic diagram illustrating the preload principle of the X-axis displacement unit and the Y-axis displacement unit in this invention; Figure 10 Examples of correct and incorrect methods for engaging off-axis loads with piezoelectric ceramic stacks; Figure 11 This is a schematic diagram of strain gauge bonding in a Z-axis displacement element; Figure 12 This is a flowchart of signal processing for SGS sensor closed-loop control. Figure 13 The diagram showing the relationship between force and displacement in the flexible hinge of this invention.

[0023] The components are: 1-Main body, 2-Z-axis displacement unit, 21-Z-axis piezoelectric drive assembly, 22-Z-axis triangular amplification mechanism, 221-Base, 222-Flexible hinge arm, 23-Z-axis output block, 3-X-axis displacement unit, 31-X-axis piezoelectric drive assembly, 32-X-axis triangular amplification mechanism, 33-X-axis output block, 331-X-axis output block fixed end, 332-X-axis output block moving end, 333-X-axis output block flexible hinge, 4-Y-axis displacement unit, 41-Y-axis piezoelectric drive assembly, 42-Y-axis triangular amplification mechanism, 43-Y-axis output block, 5-Stage, 6-Conical tail cap, 7-Screw plug, 8-Left side cover plate, 9-Right side cover plate, 10-First partition plate, 11-Second partition plate, 12-SGS strain gauge A, 13-SGS strain gauge B. Detailed Implementation

[0024] To better understand the purpose, structure, and function of this invention, the technical solutions of this invention will be described in detail, clearly, and completely below with reference to the accompanying drawings. The described technical solutions and embodiments are part of this invention, but not all of them. Based on the embodiments and technical solutions of this invention, all other embodiments and technical solutions obtained by those skilled in the art without making creative innovations are within the protection scope of this invention.

[0025] Example 1: In response to the common technical defects of existing triaxial piezoelectric flexible hinge platforms, such as "difficult maintenance due to the indivisibility of individual units", "uneven stiffness of series cantilever structures" and "lack of effective pre-tightening protection for piezoelectric ceramics", this embodiment provides a stacked triaxial piezoelectric flexible hinge platform.

[0026] For ease of description, let the vertical direction be the Z-direction, and the two mutually perpendicular directions in the horizontal plane be the X-direction and the Y-direction; for example Figure 1 and Figure 2As shown, the hinge platform is a stacked structure along the Z-axis, consisting of, from bottom to top: a main body 1 with a Z-axis displacement unit 2, an X-axis displacement unit 3, a Y-axis displacement unit 4, and a platform 5; a first partition 10 is provided between the main body 1 and the X-axis displacement unit 3, and a second partition 11 is provided between the X-axis displacement unit 3 and the Y-axis displacement unit 4.

[0027] Z-axis displacement unit 2, X-axis displacement unit 3, and Y-axis displacement unit 4 are all piezoelectric flexible hinge positioning platforms. Z-axis displacement unit 2 includes a Z-axis piezoelectric drive assembly 21, a Z-axis triangular amplification mechanism 22, and a Z-axis pre-tightening assembly. Z-axis displacement unit 2 is mounted on the main body 1. X-axis displacement unit 3 includes an X-axis piezoelectric drive assembly 31 and an X-axis triangular amplification mechanism 32. X-axis displacement unit 3 is mounted on the X-axis output block 33 to form an X-axis displacement module. Y-axis displacement unit 4 includes a Y-axis piezoelectric drive assembly 41 and a Y-axis triangular amplification mechanism 42. Y-axis displacement unit 4 is mounted on the Y-axis output block 43 to form a Y-axis displacement module.

[0028] As an example, the Z-axis piezoelectric drive assembly 21, the X-axis piezoelectric drive assembly 31, and the Y-axis piezoelectric drive assembly 41 all employ piezoelectric stacks.

[0029] like Figure 3 and Figure 4 As shown, the Z-axis displacement unit 2, X-axis displacement unit 3, and Y-axis displacement unit 4 all adopt an integrated flexible hinge transmission, which generates driving force through the inverse piezoelectric effect of piezoelectric ceramics, and realizes displacement transmission and geometric amplification by utilizing the elastic deformation of the flexible hinge.

[0030] The specific working principle of Z-axis displacement element 2 is as follows: like Figure 3 As shown, the Z-axis displacement unit 2 is generally flat and vertically arranged; the Z-axis triangular amplification mechanism 22 includes: a base 221 and flexible hinge arms 222 (elastic arms). The central area of ​​the base 221 has a through piezoelectric ceramic mounting groove. The Z-axis piezoelectric drive assembly 21 is disposed in the piezoelectric ceramic mounting groove in the central area of ​​the base 221 and connected to the connecting parts at both ends of the mounting groove; a flexible hinge arm 222 is provided at each of the two opposite ends of the Z-axis piezoelectric drive assembly 21 (i.e., the two opposite ends in the vertical direction). A vertical flexible hinge is provided at the top center of the Z-axis displacement unit 2 as a Z-axis output block 23; a vertical flexible hinge is provided at the bottom center for connecting the main body 1, and the main body 1 is fixed. The Z-axis output block 23 converges the motion trajectories from both sides and outputs them.

[0031] In Z-axis displacement unit 2, the movement of the Z-axis piezoelectric drive assembly 21 directly acts on the root of the adjacent oblique flexible hinge arm 222. The flexible hinge arms 222 on both sides are arranged symmetrically in a figure-eight or inverted V shape (in this example, the upper flexible hinge arm is inverted V shape, the lower flexible hinge arm is figure-eight shape, and the flexible hinge arms on both sides are arranged symmetrically). When the Z-axis piezoelectric drive assembly 21 extends horizontally, it forces the flexible hinge arms 222 on both sides to undergo a slight inward bending deformation. The top vertical flexible hinge (i.e., Z-axis output block 23) serves as the motion convergence point, superimposing the vertical component displacements generated by the bending of the flexible hinge arms on both sides, transforming them into a significantly increased vertical displacement at the top output end, thereby achieving amplified output of the micro-displacement.

[0032] The working principle of X-axis displacement unit 3 and Y-axis displacement unit 4 is the same as that of Z-axis displacement unit 2, except that the output displacement direction is different when the piezoelectric ceramic is excited (the triangular amplification mechanism in Z-axis displacement unit 2 is inward-facing, while the triangular amplification mechanism in X-axis displacement unit 3 and Y-axis displacement unit 4 is outward-facing). Taking X-axis displacement unit 3 as an example, ... Figure 4 As shown, the X-axis displacement unit 3 is horizontally positioned, and the X-axis piezoelectric drive assembly 31 is placed in the piezoelectric ceramic mounting slot inside the X-axis delta amplification mechanism 32. At both ends of the X-axis delta amplification mechanism 32, one end is connected to the moving end of the X-axis output block 33, and the other end is connected to the fixed end of the X-axis output block 33. Similarly, the Y-axis displacement unit 4 is horizontally positioned, and the Y-axis piezoelectric drive assembly 41 is placed in the piezoelectric ceramic mounting slot inside the Y-axis delta amplification mechanism 42. At both ends of the Y-axis delta amplification mechanism 42, one end is connected to the moving end of the Y-axis output block 43, and the other end is connected to the fixed end of the Y-axis output block 43.

[0033] The overall connection relationship of this stacked triaxial piezoelectric flexible hinge platform is as follows: like Figure 5 As shown, the Z-axis displacement unit 2 is installed inside the main body 1, which has a fixed end and a moving end along the Z-axis; the top plate of the main body 1 is the moving end, and the bottom plate is the fixed end. A shallow groove is pre-drilled on the surface of the Z-axis output block 23 at the top of the Z-axis displacement unit 2 to house the Z-axis preload assembly. The Z-axis preload assembly includes a conical tail cap 6 and a screw plug 7; the lower end of the conical tail cap 6 is located within the shallow groove on the surface of the Z-axis output block 23, and the upper end passes through a hole in the top plate of the main body 1 and is screwed to the screw plug 7 (using a fine-thread screw plug), connecting the Z-axis output block 23 of the Z-axis displacement unit 2 to the moving end of the main body 1. Thus, the top plate of the main body 1 serves as the external output end of the Z-axis. The lower end of the screw plug 7 is hemispherical and self-aligning with the conical tail cap 6. The two sides of the main body 1 are sealed using a left cover plate 8 and a right cover plate 9, respectively. The top plate of the main body 1 (the moving end of the main body 1) is detachably fitted with a first partition plate 10 using screws, thus completing the assembly of the Z-axis displacement unit 2.

[0034] As an example, the top plate of the main body 1 is connected to the outer frame of the main body 1 by flexible hinges (narrow necks connecting the top plate of the main body 1 and the outer frame) to enable the top plate to move relative to the outer frame.

[0035] As an example, the first partition 10 is machined with wire holes and weight reduction holes.

[0036] The X-axis output block 33 is detachably mounted on the first partition 10 by screws; the X-axis output block 33 has a fixed end and a movable end along the X direction; the X-axis displacement unit 3 is mounted on the X-axis output block 33 (the X-axis output block 33 is provided with a corresponding mounting groove), wherein one end of the X-axis displacement unit 3 is connected to the fixed end of the X-axis output block 33 and the other end is connected to the movable end of the X-axis output block 33 at both ends in the X direction.

[0037] As an example, such as Figure 6 As shown, the outer frame of the X-axis output block 33 is its fixed end (i.e., the fixed end 331 of the X-axis output block in the figure), which is mounted on the first partition 10; the middle part is its moving end (i.e., the moving end 332 of the X-axis output block in the figure), and its fixed end and output end are connected by a flexible hinge (the narrow neck between the two, i.e., the flexible hinge 333 of the X-axis output block in the figure). At both ends of the X-axis displacement unit 3, one end is fixedly connected to the outer frame of the X-axis output block 33, and the other end is connected to the moving end of the flexible hinge in the middle.

[0038] As an example, such as Figure 6 As shown, the flexible hinge 333 of the X-axis output block uses a loop-shaped symmetrical distribution structure (symmetrical about the X-axis displacement unit 3 along the X-axis axis of symmetry), which can effectively resist lateral interference and maximize the guarantee of movement in the output direction. Figure 13 As shown, the use of a loop-shaped flexible hinge provides significant resistance when subjected to loads in the non-moving direction, which plays a significant decoupling role when outputting displacement in different directions, reducing coupling errors.

[0039] The second partition 11 is detachably mounted on the top of the X-axis output block 33 by screws and is connected to the flexible hinge moving end of the X-axis output block 33. The Y-axis output block 43 has a fixed end and a moving end along the Y direction; the Y-axis displacement unit 4 is mounted on the Y-axis output block 43, wherein one end of the Y-axis displacement unit 4 is connected to the fixed end of the Y-axis output block 43, and the other end is connected to the moving end of the Y-axis output block 43.

[0040] The connection method between the Y-axis output block 43 and the Y-axis displacement unit 4 is the same as the connection method between the X-axis output block 33 and the X-axis displacement unit 3, only the displacement output direction is different. As an example, such as... Figure 7As shown, the outer frame of the Y-axis output block 43 is its fixed end, which is mounted on the second partition 11; the middle part is its moving end, and its fixed end and output end are connected by a flexible hinge (the narrow neck between the two). At both ends of the Y-axis displacement unit 4, one end is fixedly connected to the outer frame of the Y-axis output block 43, and the other end is connected to the moving end of the flexible hinge in the middle.

[0041] As an example, such as Figure 7 As shown, the flexible hinge of the Y-axis output block uses a loop-shaped symmetrical distribution structure (symmetrical about the Y-axis displacement unit 4 along the Y-axis axis of symmetry), which can effectively resist lateral interference and maximize the guarantee of movement in the output direction.

[0042] Finally, the stage 5 is installed on top of the Y-axis output block 43 and connected to its moving end, thus completing the platform assembly.

[0043] Since the Z-axis displacement unit 2, X-axis displacement unit 3, and Y-axis displacement unit 4 output different displacement directions when stimulating the piezoelectric ceramic, different pre-tightening methods are formulated based on this special characteristic.

[0044] For Z-axis displacement element 2, such as Figure 8 As shown, when voltage is applied to the Z-axis displacement unit 2, according to the inverse piezoelectric effect, the piezoelectric ceramic expands, and the output end faces upward. Therefore, when subjected to pressure from the upper end, the structure contracts, and the piezoelectric ceramic (i.e., the Z-axis piezoelectric drive assembly 21) is subjected to pressure, which acts as a pre-tightening agent. Based on this, the Z-axis displacement unit 2 uses a conical tail cap 6 and a screw plug 7 for pre-tightening. The pre-tightening force is roughly determined by simulation to find the screw plug 7's insertion depth. At the same time, utilizing the positive piezoelectric effect, a charge detector is used to detect the charge release of the piezoelectric ceramic, further precisely controlling the pre-tightening force of the piezoelectric ceramic. The conical tail cap 6 and the hemispherical screw plug 7 are adaptively coaxial, which allows for better uniform force distribution during output.

[0045] like Figure 10 As shown, compared to the direct planar contact method, the combination of the conical tail cap 6 and the hemispherical screw plug 7 not only distributes the applied force of the external load evenly on the entire cross-section of the piezoelectric stack, but more importantly, it plays the role of force axis guidance, ensuring that the driving force is strictly transmitted along the preset translation axis and avoiding the generation of overturning moment.

[0046] The X-axis displacement unit 3 and the Y-axis displacement unit 4, when installing piezoelectric ceramics, use the sliding table to press and self-tighten the rigidity of the triangular amplification mechanism's curved arm beam (i.e., flexible hinge arm) through the pressure of the triangular amplification mechanism.

[0047] Taking X-axis displacement element 3 as an example, such as Figure 9As shown, before installing the X-axis piezoelectric drive assembly 31, connect a slide table to each end of the X-axis delta amplification mechanism 32 in the X direction. The two opposing slide tables can move towards each other in the X direction (for ease of operation, one end can be fixed, and only the slide table at the other end can be moved), squeezing its flexible hinge arm to apply pressure. The movement position of the slide table is roughly found through simulation, and then the charge release amount of the piezoelectric ceramic is detected using a charge detector to further precisely control the preload of the piezoelectric ceramic. After squeezing, the groove in the middle where the piezoelectric ceramic is installed will open. At this time, install the X-axis piezoelectric drive assembly 31 (i.e., the piezoelectric ceramic) and fill it with glue. After the glue cures, restore the X-axis delta amplification mechanism 32 (i.e., the two ends of the X-axis delta amplification mechanism 32 in the X direction move away from each other and return to the initial position without pressure). At this time, the groove in the middle where the piezoelectric ceramic is installed squeezes inward and contracts, completing the preload.

[0048] In this flexible hinge platform, the three-axis displacement units are combined by stacking, which facilitates the replacement of different loads and strokes, as well as positioning and inspection. Each motion module is separated by a partition, and the decoupling effect in the non-motion direction is very effective. In addition, the piezoelectric ceramic pre-tightening method in this solution is precise, simple and efficient, ensuring output stability and service life.

[0049] Furthermore, in this flexible hinge platform, since only the Z-axis displacement unit is installed inside the main body, the X-axis displacement unit, Y-axis displacement unit, and stage are stacked sequentially on top of the main body and separated by partitions. Therefore, when in use, the platform can be easily changed into any two-axis biaxial piezoelectric flexible hinge platform or any single-axis monoaxial piezoelectric flexible hinge platform according to actual needs.

[0050] For example, by removing the Y-axis displacement unit and installing the stage on top of the Y-axis displacement unit, a two-axis piezoelectric flexible hinge platform with Z and X axes can be formed; or by removing the X-axis displacement unit and directly installing the Y-axis displacement unit and the stage on top of the Z-axis displacement unit, a two-axis piezoelectric flexible hinge platform with Z and Y axes can be formed; or by removing the main body and fixing the fixed end of the X-axis output block, a two-axis piezoelectric flexible hinge platform with X and Y axes can be formed.

[0051] Only the main body with the Z-axis displacement unit is retained, and the stage is directly installed on top of the Z-axis displacement block to form a Z-axis uniaxial piezoelectric flexible hinge platform; only the X-axis displacement module is retained, and the stage is directly installed on top of the X-axis output block to form an X-axis uniaxial piezoelectric flexible hinge platform; only the Y-axis displacement module and the stage are retained to form a Y-axis uniaxial piezoelectric flexible hinge platform.

[0052] Example 2: Based on the above embodiment 1, further, an SGS sensor is used for precision displacement measurement feedback adjustment.

[0053] To overcome the inherent hysteresis and creep nonlinearity of piezoelectric ceramics during the driving process, this embodiment integrates a surface-mounted strain gauge (SGS) as a displacement feedback unit at key stress-bearing parts of the flexible hinge (such as the output end of the amplification mechanism or the root of the hinge).

[0054] For Z-axis displacement element 2, such as Figure 11 As shown, SGS strain gauges A12 are bonded to the surface of the moving end (i.e., its top plate) of the main body 1. In this example, four SGS strain gauges A12 are rectangularly distributed on the surface of the top plate of the main body 1.

[0055] For X-axis displacement element 3 and Y-axis displacement element 4, such as Figure 6 and Figure 7 As shown, these two motion modules have similar functions. They both use a triangular amplification mechanism to transmit the output displacement to the middle working platform area (i.e., the flexible hinge moving end in the middle of its output block). Based on this, SGS strain gauges B13 are attached to the flexible hinge deformation points of the X-axis output block 33 and the Y-axis output block 43 for measurement and feedback (the blank area in the middle of the working platform area in the figure is the machined wire hole) to achieve high-precision positioning.

[0056] Furthermore, the feedback mechanism in this scheme is based on the elastic deformation-driven displacement mapping principle of the flexible hinge to measure the final displacement of the measuring stage (each moving end): when the piezoelectric ceramic is energized and generates a micro-axial displacement, it drives the displacement amplification mechanism to rotate slightly, thereby causing the flexible hinge to bend macroscopically. During this process, the SGS strain gauges attached to the surface of the flexible hinge sense the micro-strain generated by the force in real time and convert it into a corresponding change in resistance. The hardware circuit detects the resistance change of the SGS strain gauges and processes this change to measure the final displacement.

[0057] The specific closed-loop control process is as follows: Figure 12 As shown: The weak resistance signal generated by the SGS strain gauge is amplified by the sensing servo unit and then converted into a digital signal by a high-precision analog-to-digital converter (ADC) circuit, which is then input to the main control unit (MCU). The main control unit compares the actual measured real-time displacement with the externally input ideal target displacement value, processes it using a proportional-integral-derivative (PID) algorithm, and outputs a control quantity to the power amplifier module, thereby driving the piezoelectric ceramic to perform dynamic compensation.

[0058] Thanks to the high linearity of the transmission relationship between the deformation of the flexible hinge and the output displacement, this scheme can avoid the nonlinear error of piezoelectric ceramics at the source and achieve nanometer-level (nm) precision closed-loop control of the positioning stage's output displacement. Simultaneously, since the strain signal directly reflects the instantaneous response of the mechanical structure, this control loop has an extremely fast response speed, achieving millisecond-level (<1ms) step responses, ensuring the trajectory accuracy and stability of the platform during dynamic scanning.

[0059] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A stacked triaxial piezoelectric flexible hinge platform, characterized in that, The hinge platform is a stacked structure along the Z-axis, consisting of, from bottom to top: a main body with a Z-axis displacement unit, an X-axis displacement unit, a Y-axis displacement unit, and a stage. The Z-axis displacement unit, X-axis displacement unit and Y-axis displacement unit are all piezoelectric flexible hinge positioning platforms; The Z-axis displacement unit is installed inside the main body, which has a fixed end and a moving end along the Z direction; the top of the Z-axis displacement unit has a Z-axis output block; the Z-axis output block is connected to the moving end of the main body; the moving end of the main body is equipped with a first partition. The X-axis output block is mounted on the first partition; the X-axis output block has a fixed end and a movable end along the X direction; the X-axis displacement unit is mounted on the X-axis output block, and one end of the X-axis displacement unit is connected to the fixed end of the X-axis output block, and the other end is connected to the movable end of the X-axis output block. The second partition is installed on the moving end of the X-axis output block; the Y-axis output block is installed on the second partition; the Y-axis output block has a fixed end and a moving end along the Y direction; the Y-axis displacement unit is installed on the Y-axis output block, wherein one end of the Y-axis displacement unit is connected to the fixed end of the Y-axis output block and the other end is connected to the moving end of the Y-axis output block at both ends in the Y direction. The stage is connected to the moving end of the Y-axis output block.

2. The stacked triaxial piezoelectric flexible hinge platform as described in claim 1, characterized in that, A shallow groove is reserved on the surface of the Z-axis output block at the top of the Z-axis displacement unit for placing the Z-axis preload assembly. The Z-axis preload assembly includes a tapered tail cap and a screw plug; the lower end of the tapered tail cap is located in a shallow groove on the surface of the Z-axis output block, and the upper end passes through a hole on the top plate of the main body and is screwed to the screw plug, which is used to connect the Z-axis output block to the moving end of the main body. The lower end of the screw plug is hemispherical and adaptively coaxial with the conical tail cap.

3. The stacked triaxial piezoelectric flexible hinge platform as described in claim 1 or 2, characterized in that, The top plate of the main body is its movable end. The top plate is connected to the outer frame of the main body through flexible hinges around its perimeter, so as to realize the movement of the top plate relative to the outer frame.

4. The stacked triaxial piezoelectric flexible hinge platform as described in claim 1 or 2, characterized in that, The Z-axis displacement unit includes: a Z-axis piezoelectric drive assembly and a Z-axis triangular amplification mechanism; The Z-axis triangular amplification mechanism includes: a base and a flexible hinge arm; the Z-axis piezoelectric drive assembly is disposed in the piezoelectric ceramic mounting groove in the central region of the base and is connected to the connecting parts at both ends of the mounting groove. A flexible hinge arm is provided at each of the two opposite ends of the Z-axis piezoelectric drive assembly. The top center of the Z-axis displacement unit is provided with a vertical flexible hinge as a Z-axis output block; the bottom center is provided with a vertical flexible hinge for connecting the main body, and the main body is fixed.

5. The stacked triaxial piezoelectric flexible hinge platform as described in claim 1 or 2, characterized in that, The X-axis displacement unit includes an X-axis piezoelectric drive assembly and an X-axis delta amplification mechanism; the X-axis piezoelectric drive assembly is placed in a piezoelectric ceramic mounting slot inside the X-axis delta amplification mechanism; one end of the X-axis delta amplification mechanism is connected to the moving end of the X-axis output block, and the other end is connected to the fixed end of the X-axis output block. The Y-axis displacement unit includes a Y-axis piezoelectric drive assembly and a Y-axis delta amplification mechanism. The Y-axis piezoelectric drive assembly is placed in a piezoelectric ceramic mounting slot inside the Y-axis delta amplification mechanism. At both ends of the Y-axis delta amplification mechanism, one end is connected to the moving end of the Y-axis output block, and the other end is connected to the fixed end of the Y-axis output block.

6. The stacked triaxial piezoelectric flexible hinge platform as described in claim 5, characterized in that, The outer frame of the X-axis output block is its fixed end, which is mounted on the first partition; the middle part is its movable end, and its fixed end is connected to the output end by a flexible hinge. The outer frame of the Y-axis output block is its fixed end, which is mounted on the second partition; the middle part is its movable end, and its fixed end is connected to the output end by a flexible hinge.

7. The stacked triaxial piezoelectric flexible hinge platform as described in claim 5, characterized in that, In the X-axis output block, the flexible hinge between its fixed end and output end has a loop-shaped symmetrical distribution structure. In the Y-axis output block, the flexible hinge between its fixed end and output end has a loop-shaped symmetrical distribution structure.

8. The stacked triaxial piezoelectric flexible hinge platform as described in claim 5, characterized in that, The X-axis displacement unit and Y-axis displacement unit cooperate with the slide table to press the slide table and self-pre-tighten through the stiffness of the flexible hinge arm of the triangular amplification mechanism. For the X-axis displacement unit: Before installing the X-axis piezoelectric drive assembly, connect a slide table to each end of the X-axis delta amplification mechanism in the X direction. The two oppositely positioned slide tables move towards each other in the X direction, squeezing their flexible hinge arms to apply pressure. After squeezing, the piezoelectric ceramic mounting groove in the middle is opened. Then, install the X-axis piezoelectric drive assembly and fill it with glue. After the glue cures, restore the X-axis delta amplification mechanism to its initial position. At this time, the piezoelectric ceramic mounting groove in the middle is squeezed inward and shrinks, completing the pre-tightening. The Y-axis displacement unit adopts the same preload method as the X-axis displacement unit.

9. The stacked triaxial piezoelectric flexible hinge platform as described in claim 1 or 2, characterized in that, An SGS strain gauge A is bonded to the moving end surface of the main body for measuring and feedback of Z-axis displacement. The weak resistance signal generated by the SGS strain gauge A is amplified by the sensing servo unit and then converted into a digital signal by a high-precision analog-to-digital converter circuit and input to the main control unit. The main control unit compares the actual measured real-time displacement with the externally input ideal target displacement value. After processing by the PID algorithm, it outputs the control quantity to the power amplifier module to drive the Z-axis displacement unit for dynamic compensation.

10. The stacked triaxial piezoelectric flexible hinge platform as described in claim 6 or 7, characterized in that, SGS strain gauges B are attached to the flexible hinge deformation points of the X-axis output block and Y-axis output block for displacement measurement and feedback. The weak resistance signal generated by the SGS strain gauge B is amplified by the sensing servo unit and then converted into a digital signal by a high-precision analog-to-digital converter circuit and input to the main control unit. The main control unit compares the actual measured real-time displacement with the externally input ideal target displacement value. After processing by the PID algorithm, it outputs the control quantity to the power amplifier module to drive the X-axis displacement unit and the Y-axis displacement unit to perform dynamic compensation.

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