A composite damping XYZ decoupling parallel compliant positioning platform and control method

Abstract

The present invention discloses a composite damping XYZ decoupled parallel compliant positioning platform and control method. The platform comprises a dynamic platform with an embedded gradient local resonator. The dynamic platform is connected to three kinematic branches, each of which is connected to a piezoelectric ceramic actuator. The kinematic branches include a displacement amplification mechanism and two biaxially co-located orthogonal flexible hinges, each of which has an embedded damping substructure. This invention achieves a high-bandwidth micro-nano positioning platform that can be used as a high-speed scanning platform in applications such as atomic force microscopes (AFMs) and scanning electron microscopes (SEMs).

Description

Technical Field

[0001] The present invention relates to the field of micro-manipulation, and in particular to a composite damping XYZ decoupling parallel compliant positioning platform and a control method thereof. Background Art

[0002] With the continuous development of precision machining technology and in-depth research on precision manufacturing equipment, micro-nano manipulation (micro-assembly), cell puncture, and other aspects, various fields have put forward increasingly higher requirements for precision positioning technology. Nano-precision positioning platforms are motion, positioning, and manipulation platforms with nanometer-level accuracy. As the core module of nano-manufacturing equipment, micro-nano positioning platforms based on piezoelectric-driven compliant mechanisms play an important role in the field of precision engineering. Some practical application scenarios of micro-nano positioning platforms include: as a stage for atomic force microscopes (AFM) and scanning electron microscopes (SEM); as a microinjector for cell or early embryo manipulation under multi-viewing; for controlling the precise movement of tools on high-precision micro-cutting equipment; for precise positioning of micro-grippers for dexterous manipulation of micro-nano-scale objects; and for nanoimprint lithography with ultra-high resolution and high fidelity.

[0003] These application scenarios place high demands on the performance of micro-nano positioning platforms, including scanning speed, positioning accuracy, and travel range. To meet these requirements, various methods can be used to increase the platform's control bandwidth, thereby improving its dynamic characteristics. The key components of micro-nano positioning platforms based on piezoelectrically driven compliant mechanisms include piezoelectric ceramic actuators and compliant mechanisms. Therefore, improving the platform's scanning speed and positioning accuracy primarily faces two challenges: the hysteresis nonlinearity of the piezoelectric ceramic actuators, and the lightly damped nature of the compliant mechanisms, which limits the platform's maximum motion bandwidth to 1-10% of its resonant frequency. Therefore, compensating for piezoelectric ceramic hysteresis and enhancing the damping of compliant mechanisms have become key research areas. Numerous studies have been conducted both domestically and internationally, but many focus solely on compensating for piezoelectric ceramic hysteresis while ignoring the importance of enhancing mechanism damping. Alternatively, complex active damping controllers are employed to enhance mechanism damping, often in addition to hysteresis compensation. Passive damping is rarely employed to enhance mechanism damping.

[0004] Therefore, to address the above problems, it is necessary to design a three-dimensional parallel micro-nano positioning platform using composite damping that takes into account high bandwidth, large stroke and compactness. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art three-dimensional parallel micro-nano positioning platform, such as low scanning speed and large coupling displacement, the present invention provides a composite damping XYZ decoupling parallel compliant positioning platform and a control method.

[0006] This paper proposes a new approach to improving platform scanning speed and suppressing platform coupling using a composite damping method. This method employs a composite damping method that embeds a damping substructure in the hinge and a gradient local resonator in the moving platform. The combined mass of the damper and local resonator is approximately 26.44g, representing approximately 4% of the mass of the composite damping XYZ decoupled parallel compliant positioning platform. While minimizing the added mass, this method enhances hinge damping and tunes the platform's modal damping for specific frequency bands.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A composite damping XYZ decoupled parallel compliant positioning platform includes a moving platform with an embedded gradient local resonator. The moving platform is respectively connected to three kinematic branches, each of which is connected to a piezoelectric ceramic actuator. The kinematic branches include a displacement amplification mechanism and two biaxial co-located orthogonal flexible hinges, each of which has an embedded damping substructure.

[0009] Furthermore, the two coaxial, co-located orthogonal flexible hinges are arranged in a mirror image and are in a series relationship.

[0010] Furthermore, the coaxial, co-located, orthogonal flexible hinge is constructed by a circular through hole and an oblique opening, and has two orthogonal rotational degrees of freedom, and the damping substructure is embedded in the circular through hole.

[0011] Furthermore, the damping substructure includes an opening sealing ring, a viscoelastic damping material and an inner plug with a trapezoidal annular groove, and the inner plug and the opening sealing ring are bonded by the viscoelastic damping material.

[0012] Furthermore, the gradient local resonator includes 27 local resonance units and a three-layer nine-square grid frame. Each layer of the nine-square grid frame is equipped with 9 local resonance units. Each local resonance unit is composed of lead balls of different diameters wrapped in a homogeneous silica gel layer, forming an independent parallel relationship with the moving platform.

[0013] Furthermore, it also includes a rigid frame, which includes three base plates. The three base plates are arranged orthogonally in pairs, and two adjacent base plates are connected by triangular ribs. The displacement amplification mechanism is fixed on the base plates.

[0014] Furthermore, each layer of the nine-square grid frame is provided with 9 local resonance units, and the nine local resonance units include 3 2mm lead balls, 5 3mm lead balls, and 1 4mm lead ball.

[0015] Furthermore, the 4mm lead shot is located in the upper right corner of the nine-square grid, the three 2mm lead shots are located in the upper left corner and the lower right corner of the nine-square grid, and the 3mm lead shots are set in the remaining positions.

[0016] A control method for a composite damped XYZ decoupled parallel compliant positioning platform is disclosed. A control signal drives a piezoelectric ceramic actuator, causing it to generate a small input displacement to a displacement amplification mechanism. After amplification, the displacement is transmitted to two coaxial, co-located orthogonal flexible hinges to transmit the displacement to a moving platform. At the same time, the motion branches of other axes passively generate coupled motion. The coupled displacement of the moving platform is greatly suppressed through the spatial rotation of the two-axis co-located orthogonal hinges at the head and tail ends and the damping substructure embedded therein. When the three axes move together, the motion trajectory of the moving platform is a composite trajectory of the motion trajectories of the three axes.

[0017] An atomic force microscope comprises the composite damping XYZ decoupling parallel compliant positioning platform.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] (1) Each motion branch of the present invention adopts a bridge-type amplification mechanism, which effectively expands the travel range of the platform;

[0020] (2) Each kinematic branch of the present invention adopts a combination of two biaxial co-located orthogonal hinges connected in series, thereby achieving kinematic decoupling of the XYZ parallel micro-nano positioning platform;

[0021] (3) The present invention designs a new cylindrical damping substructure based on the structural characteristics of the biaxial co-located orthogonal hinge, which effectively improves the light damping characteristics of the metal-based orthogonal hinge, and achieves the enhancement of hinge damping while suppressing inter-axis coupling.

[0022] (4) The present invention introduces a gradient local resonator to enhance the modal damping of the platform on the basis of enhancing the hinge damping, thereby achieving composite damping enhancement of the platform and effectively improving the control bandwidth of the platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a composite damping XYZ decoupling parallel compliant positioning platform of the present invention;

[0024] Figure 2 It is a structural schematic diagram of the dynamic platform of the present invention;

[0025] Figure 3 Schematic diagram of the motion branched chain structure of the present invention;

[0026] Figure 4 Schematic diagram of the displacement amplification mechanism of the present invention;

[0027] Figure 5 It is a schematic diagram of the rigid frame structure of the present invention;

[0028] Figure 6 1 is a schematic structural diagram of a piezoelectric ceramic actuator according to the present invention;

[0029] FIG7( a ) and FIG7 ( b ) are respectively a schematic structural diagram and a cross-sectional view of the damping substructure of the present invention;

[0030] Figure 8 It is a control flow diagram of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0032] Example 1

[0033] like Figure 1 The figure shows a composite damping XYZ decoupled parallel compliant positioning platform, a three-dimensional micro-nano positioning platform. It primarily includes a moving platform 1, a kinematic branch chain 2, a rigid frame 3, a piezoelectric ceramic actuator 4 with strain gauges, a damping substructure 5, and a control system. The control system includes a host computer equipped with MATLAB / Simulink for control system development and a dSPACE real-time simulation control board connected to a piezoelectric ceramic driver to control the motion of the piezoelectric ceramic actuator.

[0034] The dynamic platform 1 is a cubic cavity with an embedded gradient local resonator and an external stage, used to carry the sample under test for scanning motion. Specifically, it comprises a base 101, a gradient local resonator, and a stage 103. The base 101 is positioned with one end of three orthogonally arranged kinematic branches 2 via cylindrical pins and threaded connections. The dynamic platform 1 and the three kinematic branches 2 are connected in parallel.

[0035] Furthermore, the gradient local resonator is composed of 27 local resonance units 102-1 and three nine-square grid frames 102-2, which are embedded in the cavity of the substrate 101 and are used to tune the modal damping of the platform. The three nine-square grid frames are stacked, and each nine-square grid frame is equipped with nine local resonance units. The local resonance unit 102-1 is made of a homogeneous silica gel layer coated with lead balls of different diameters, which are respectively embedded in each grid of the frame to form an independent parallel relationship with the moving platform. The stage 103 is embedded in the stepped countersunk hole of the substrate 101, and is used to carry the sample to be tested and limit the relative movement between the gradient local resonator and the substrate 101. Figure 2 shown.

[0036] Specifically, the local resonant superstructure module described in this embodiment includes three single-layer local resonant unit arrays, and each layer of the local resonant unit array is arranged in a nine-square grid frame. The single-layer local resonant unit array includes 3 2mm lead balls, 5 3mm lead balls, and 1 4mm lead ball, and 2mm, 3mm and 4mm represent the inner diameter of the silicone layer or the diameter of the lead ball.

[0037] The preferred setting is: the 4mm lead shot is located in the upper right corner of the nine-square grid, the three 2mm lead shots are located in the upper left corner and lower right corner of the nine-square grid respectively, and 3mm lead shots are set in the remaining positions.

[0038] There are three motion branches, which are used to provide the dynamic platform with freedom of movement. It includes a displacement amplification mechanism 201 and two biaxial co-located orthogonal flexible hinges 202, which can realize single-axial translation and rotation around the other two axes, and are used to transmit the motion and force generated by the piezoelectric ceramic actuator 3. The displacement amplification mechanism 201 can amplify the output displacement of the piezoelectric ceramic actuator 4. In this embodiment, the displacement amplification mechanism 201 is a bridge-type displacement amplification mechanism, and a butterfly-shaped displacement amplification mechanism, a diamond-shaped amplification mechanism, etc. can also be used. The biaxial co-located orthogonal flexible hinge 202 is constructed by a circular through hole and an oblique opening, and has two orthogonal rotational degrees of freedom. The two rotating axes are orthogonal to each other at one point, and the cross section is square. The two biaxial co-located orthogonal flexible hinges 202 are in a series relationship and are arranged in a mirror image. The specific structure is as follows Figure 3 and Figure 4 shown.

[0039] The two coaxial co-located orthogonal flexible hinges are embedded with a damping substructure 5, which is composed of an open sealing ring 501, a viscoelastic damping material 502 and an insert 503 with a trapezoidal annular groove. The open sealing ring 501 and the insert 503 are connected together by the viscosity of the viscoelastic damping material. In this embodiment, a total of 48 damping substructures are included, which are respectively embedded in the circular through holes of each biaxial co-located orthogonal flexible hinge 202 to enhance the damping of the metal-based flexible hinge, improve the control bandwidth of the platform, and suppress the inter-axis coupling of the parallel platform. The specific structure is as follows Figure 1 and Figure 7(a) to Figure 7(b) shown.

[0040] Specifically, two side surfaces and one bottom surface of the moving platform are respectively connected to three motion branches to form XYZ axis degrees of freedom.

[0041] The rigid frame 3 is used to provide rigid support for the present invention. The rigid frame includes a left substrate 301, a rear substrate 302, a bottom substrate 303, and three triangular ribs 304. The three substrates are arranged orthogonally in pairs and connected to each other by screws. One triangular rib 304 is connected to two substrates by screws at the same time. The ends of the displacement amplification mechanisms 201 of each motion branch 2 are fastened to the left substrate 301, the rear substrate 302, and the bottom substrate 303 respectively. The specific structure is as follows: Figure 5 shown.

[0042] In this embodiment, the three substrates have the same structure and are all made of 8 mm thick aluminum plates.

[0043] The piezoelectric ceramic actuator 4 is manufactured by Piezodrive, an Australian company, and its model is SCL050518. It is equipped with a matching piezoelectric ceramic driver, including a stacked piezoelectric ceramic 401 and a full-bridge strain displacement sensor 402 encapsulated thereon. The piezoelectric ceramic actuator 4 drives each motion branch to move according to the input signal, thereby causing the moving platform to generate a scanning motion corresponding to the signal. The full-bridge strain displacement sensor 402 is used to measure the output displacement of the stacked piezoelectric ceramic 401. The specific structure is as follows: Figure 6 shown.

[0044] In this embodiment, the configuration of the above platform is named 3 ⊥ (P ⊥ K ∥ K). Among them, 3 ⊥ (…) represents three axes that are orthogonal to each other and in parallel; P represents a displacement amplification mechanism 201 with a piezoelectric ceramic actuator 4; K represents a biaxial co-located orthogonal flexible hinge 202 with two orthogonal rotational degrees of freedom; P ⊥ K represents that the actuating axis of the displacement amplifying mechanism 201 and the two rotating axes of the biaxial co-located orthogonal flexible hinge 202 are perpendicular to each other; ∥ K represents that the rotation axes of the two biaxial co-located orthogonal flexible hinges 202 are parallel to each other, that is, the two biaxial co-located orthogonal flexible hinges 202 are in a series relationship. This configuration can achieve kinematic decoupling of the mechanism.

[0045] like Figure 8 As shown, the specific workflow of this embodiment is:

[0046] The control system generates a 0-10V control signal that is input to the piezoelectric ceramic driver. After amplification, the piezoelectric ceramic driver outputs a 0-150V voltage to the piezoelectric ceramic actuator 3, causing it to generate a small input displacement in the displacement amplifier mechanism 201. A full-bridge strain sensor 402, mounted on the surface of the stacked piezoelectric ceramic 401, measures this input displacement and performs analog-to-digital conversion via the ADC port on the dSPACE real-time simulation control board within the control system. The sensor is then transmitted to the host computer for processing, where a controller developed by the host computer implements semi-closed-loop control. The input displacement is amplified by the displacement amplifier mechanism 201 and transmitted to two biaxially co-located orthogonal flexible hinges 202. These hinges further transmit the displacement to the moving platform 1. Simultaneously, the kinematic branches 2 of the other axes passively generate coupled motion. However, the spatial rotation of the biaxially co-located orthogonal hinges 202 at both ends, along with the damping substructure 5 embedded within them, significantly suppresses the coupled displacement of the moving platform 1. When the three axes move together, the motion trajectory of the moving platform 1 is a composite trajectory of the motion trajectories of the three axes, thus enabling complex motion with three degrees of freedom in space.

[0047] Example 2

[0048] An atomic force microscope comprises the composite damping XYZ decoupling parallel compliant positioning platform.

[0049] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A composite damping XYZ decoupling parallel compliant positioning platform, characterized by: The invention comprises a moving platform, wherein the moving platform has a built-in gradient local resonator, the moving platform is respectively connected to three moving branches, each moving branch is connected to a piezoelectric ceramic actuator, the moving branches include a displacement amplification mechanism and two biaxial co-located orthogonal flexible hinges, and the biaxial co-located orthogonal flexible hinges have a built-in damping substructure; The gradient local resonator includes 27 local resonance units and a three-layer nine-square grid frame. Each layer of the nine-square grid frame is equipped with 9 local resonance units. Each local resonance unit is composed of lead balls of different diameters wrapped in a homogeneous silica layer, forming an independent parallel relationship with the moving platform. Each layer of the nine-square grid frame is provided with 9 local resonance units, and the 9 local resonance units include 3 2mm lead beads, 5 3mm lead beads, and 1 4mm lead bead; The 4mm lead ball is located in the upper right corner of the nine-square grid, the three 2mm lead balls are located in the upper left corner and the lower right corner of the nine-square grid, and 3mm lead balls are set in the remaining positions.

2. The composite damping XYZ decoupling parallel compliant positioning platform according to claim 1 is characterized in that: The two biaxial co-located orthogonal flexible hinges are arranged in a mirror image and are in a series relationship.

3. The composite damping XYZ decoupling parallel compliant positioning platform according to claim 1 is characterized in that: The biaxial co-located orthogonal flexible hinge is constructed by a circular through hole and an oblique opening, and has two orthogonal rotational degrees of freedom. The damping substructure is embedded in the circular through hole.

4. The composite damping XYZ decoupling parallel compliant positioning platform according to any one of claims 1 to 3, characterized in that: The damping substructure comprises an opening sealing ring, a viscoelastic damping material and an inner plug-in unit with a trapezoidal annular groove. The inner plug-in unit and the opening sealing ring are bonded by the viscoelastic damping material.

5. The composite damping XYZ decoupling parallel compliant positioning platform according to claim 1, characterized in that: It also includes a rigid frame, which includes three base plates. The three base plates are arranged orthogonally in pairs, and two adjacent base plates are connected by triangular ribs. The displacement amplification mechanism is fixed on the base plates.

6. A control method based on the composite damping XYZ decoupling parallel compliant positioning platform according to any one of claims 1 to 5, characterized in that: The control signal drives the piezoelectric ceramic actuator, causing it to generate a tiny input displacement to the displacement amplification mechanism. After amplification, the displacement is transmitted to two biaxial co-located orthogonal flexible hinges, and the displacement is transmitted to the moving platform. At the same time, the motion branches of the other axes passively generate coupled motion. The spatial rotation of the biaxial co-located orthogonal hinges at the head and tail ends and the damping substructure embedded therein greatly suppress the coupled displacement of the moving platform. When the three axes move together, the motion trajectory of the moving platform is the composite trajectory of the motion trajectories of the three axes.

7. An atomic force microscope, characterized in that It comprises the composite damping XYZ decoupling parallel compliant positioning platform as described in any one of claims 1 to 5.

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