Two-degree-of-freedom stick-slip driving positioning platform based on spatial parasitic motion mechanism

Abstract

The application discloses a two-degree-of-freedom stick-slip driving positioning platform based on a spatial parasitic motion mechanism, which comprises a base, two x-direction cross roller guides arranged in parallel and installed on the base, a connecting frame installed on the two x-direction cross roller guides, two y-direction cross roller guides installed on the connecting frame, and a motion platform installed on the two y-direction cross roller guides, wherein the motion platform is driven by the spatial parasitic motion mechanism, the spatial parasitic motion mechanism is provided with three parallel and circumferentially-distributed branch chains, and the horizontal projection of one of the branch chains extends along the y direction; each branch chain is provided with an X-shaped flexible hinge, a leaf-shaped flexible hinge and a double-parallel leaf-shaped flexible hinge which are arranged in series from top to bottom. The application has the characteristics of large stroke, high precision, high resolution and output decoupling, and has the characteristics of good isotropy, good dynamic characteristics, few drivers and large output force of forward and reverse bidirectional motion.

Description

Technical Field

[0001] This invention relates to positioning platforms, and more particularly to a two-degree-of-freedom, large-stroke, high-precision positioning platform that utilizes a piezoelectric ceramic drive and a spatial parasitic motion mechanism to provide clamping force and feed motion. It is suitable for applications in micro / nano manipulation, micro / nano fabrication, and micro / nano testing. Background Technology

[0002] With the development of nanotechnology, piezoelectric ceramic-driven positioning platforms based on the stick-slip principle have advantages such as large stroke, high precision, and high resolution. They are widely used in fields requiring fine operation, such as micro-product assembly, ultra-precision machining and manufacturing, X-ray lithography, scanning electron microscopy, and confocal microscopy, and have become an indispensable part of micro-nano science.

[0003] For a stick-slip driven positioning platform, its drive mechanism clamps the moving platform, providing clamping force. During the viscous motion phase, it feeds slowly, providing static friction in the feed direction. During the sliding motion phase, it contracts rapidly, providing sliding friction in the opposite direction of the feed. The stick-slip driven positioning platform utilizes the difference between the positive displacement generated by static friction and the retraction displacement caused by sliding friction, periodically superimposing these values ​​to achieve large-stroke, high-precision displacement output. The load capacity of the stick-slip driven positioning platform is positively correlated with the friction force; however, excessively high friction will increase the retraction displacement during the sliding motion phase, thus severely affecting the speed and output efficiency of the stick-slip driven positioning platform.

[0004] Jilin University disclosed a "device for suppressing the retraction motion of parasitic piezoelectric actuators using an arc-shaped hinge" in its patent publication number CN208597034U. Parasitic motion drive mechanisms can generate oblique driving displacement, utilizing parasitic displacement along the normal direction of the contact surface to continuously increase friction during the sticky process and continuously decrease friction during the sliding process, thus increasing load capacity while reducing retraction displacement. However, existing stick-slip drive positioning platforms based on parasitic motion drive mechanisms are all single-degree-of-freedom positioning platforms. To achieve two-degree-of-freedom motion, two single-degree-of-freedom stick-slip drive positioning platforms must be directly stacked, orthogonal, and connected in series. However, during motion, the upper platform acts as an external load for the lower platform, leading to differences in the dynamic characteristics and load capacity of the upper and lower platforms. Ultimately, this results in significant differences in the dynamic characteristics, load capacity, retraction displacement, and speed of the two-degree-of-freedom stick-slip drive positioning platform along the two motion directions. Summary of the Invention

[0005] This invention provides a two-degree-of-freedom stick-slip driven positioning platform based on a spatial parasitic motion mechanism to solve the technical problems existing in the prior art. This positioning platform not only has the characteristics of large stroke, high accuracy, high resolution and output decoupling, but also has the characteristics of good isotropy, good dynamic characteristics, few actuators and large forward and reverse output forces.

[0006] The technical solution adopted by this invention to solve the technical problems existing in the prior art is as follows: a two-degree-of-freedom stick-slip driven positioning platform based on a space parasitic motion mechanism, comprising a base, on which two parallel x-direction cross roller guides are mounted, a connecting frame is mounted on the two x-direction cross roller guides, and on the connecting frame, two y-direction cross roller guides are mounted, and a motion platform is mounted on the two y-direction cross roller guides. The motion platform is driven by a space parasitic motion mechanism, which has three parallel branches evenly distributed circumferentially, and one of the branches has a horizontal projection extending along the y-direction. Each branch has an X-shaped flexible hinge and a leaf-shaped flexible hinge arranged in series from top to bottom. The system comprises a chain and a double parallel leaf-shaped flexible hinge. The leaf-shaped flexible hinge is upward at a 45° angle, and its plane is perpendicular to the xy plane. One leg of the X-shaped flexible hinge is vertical, and the other leg is at a 45° angle to the xy plane and perpendicular to the leaf-shaped flexible hinge. The double parallel leaf-shaped flexible hinge is parallel to the xy plane. The upper ends of the three chains are connected in parallel to a ball joint, and the lower ends are connected in parallel to a column. The column is fixed on a ceramic mounting base. Each chain is driven by a piezoelectric ceramic, which is vertically mounted on the ceramic mounting base and preloaded by a preload bolt connected to the ceramic mounting base. The ceramic mounting base is fixed to the base, and the ball joint contacts the bottom surface of the motion platform.

[0007] The advantages and positive effects of this invention are as follows: It adopts the piezoelectric stick-slip drive principle, which can simultaneously meet the requirements of large stroke, high precision, and high resolution; two sets of cross roller guides are orthogonally arranged in series through a connecting frame, enabling two-degree-of-freedom uncoupled motion, avoiding the direct stacking, orthogonal, and series connection of two single-degree-of-freedom stick-slip drive positioning platforms, ensuring identical dynamic characteristics, load capacity, backlash displacement, and speed along both motion directions; the parasitic motion provided by the spatial parasitic motion mechanism can continuously increase friction during the sticking process and continuously decrease friction during the sliding process, improving output force while reducing backlash displacement; the spatial parasitic motion mechanism only requires three piezoelectric ceramics to simultaneously provide feed in two directions within the horizontal plane. The clamping force in the vertical direction is used for driving in the x and y directions, reducing the number of actuators, lowering costs, and simplifying control. The spatial parasitic motion mechanism can simultaneously achieve feed motion in both positive and negative x and y directions, avoiding the problem of low output force in the other direction caused by only being able to achieve feed motion in either the positive or negative x or y direction, thus improving the output force of bidirectional motion. The X-shaped flexible hinge, while capable of rotational deformation, ensures that the spatial parasitic motion mechanism has sufficient stiffness along the direction of the leaf-shaped flexible hinge and in the vertical direction when providing clamping force in the vertical direction, improving the output force. The ball joint ensures good point contact at all times during the driving of the motion platform by the spatial parasitic motion mechanism. In summary, the two-degree-of-freedom stick-slip driven positioning platform based on the spatial parasitic motion mechanism provided by this invention not only has the characteristics of large stroke, high accuracy, high resolution, and output decoupling, but also features good isotropy, good dynamic characteristics, fewer actuators, and large output force in both bidirectional motion. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure of the present invention;

[0009] Figure 2 This is a schematic diagram of the exploded structure of the present invention;

[0010] Figure 3 This is a top view schematic diagram of the space parasitic motion mechanism of the present invention;

[0011] Figure 4 This is a schematic diagram of the spatial parasitic motion mechanism, piezoelectric ceramic, and preload bolt of the present invention.

[0012] Figure 5 This is a schematic diagram of the parasitic motion of the spatial parasitic motion mechanism of the present invention under the drive of piezoelectric ceramics;

[0013] Figure 6 This is a schematic diagram of the piezoelectric ceramic driving voltage corresponding to the forward and reverse y-axis movements of the present invention;

[0014] Figure 7This is a schematic diagram of the piezoelectric ceramic driving voltage corresponding to the forward and reverse x-axis movements of the present invention;

[0015] Figure 8 This is a schematic diagram of the displacement output curve of the motion platform of the present invention.

[0016] In the diagram: 1. Motion platform, 2. Connecting frame, 3. Crossed roller guide rail in the x-direction, 4. Base, 5. Crossed roller guide rail in the y-direction, 6. Spatial parasitic motion mechanism, 6-1. Ball head, 6-2. X-shaped flexible hinge, 6-3. Leaf-shaped flexible hinge, 6-4. Double parallel leaf-shaped flexible hinge, 6-5. Column, 6-6. Ceramic mounting base, 7-1. Piezoelectric ceramic I, 7-2. Piezoelectric ceramic II, 7-3. Piezoelectric ceramic III, 8. Preload bolt. Detailed Implementation

[0017] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:

[0018] Please see Figures 1-6 A two-degree-of-freedom stick-slip driven positioning platform based on a spatial parasitic motion mechanism includes a base 4, on which two parallel x-direction cross roller guides 3 are mounted, a connecting frame 2 is mounted on the two x-direction cross roller guides 3, two y-direction cross roller guides 5 are mounted on the connecting frame 2, and a motion platform 1 is mounted on the two y-direction cross roller guides 5. The motion platform 1 is driven by a spatial parasitic motion mechanism 6.

[0019] The spatial parasitic motion mechanism 6 has three parallel branches evenly distributed circumferentially, with one branch's horizontal projection extending along the y-direction. Each branch has an X-shaped flexible hinge 6-2, a leaf-shaped flexible hinge 6-3, and a double parallel leaf-shaped flexible hinge 6-4 connected in series from top to bottom. The leaf-shaped flexible hinge 6-3 is upward at a 45° angle, and its plane is perpendicular to the xy-plane. One leg of the X-shaped flexible hinge 6-2 is vertical, and the other leg forms a 45° angle with the xy-plane and is perpendicular to the leaf-shaped flexible hinge 6-3. The double parallel leaf-shaped flexible hinge 6-4... Parallel to the xy plane, the upper ends of the three branches are connected in parallel to a ball head 6-1, and the lower ends are connected in parallel to a column 6-5. The column 6-5 is fixed on a ceramic mounting base 6-6. Each branch is driven by a piezoelectric ceramic, which is vertically mounted on the ceramic mounting base 6-6 and preloaded by a preload bolt 8. The preload bolt 8 is connected to the ceramic mounting base 6-6, which is fixed to the base 4. The ball head 6-1 contacts the bottom surface of the motion platform 1 and drives the motion platform 1 to move through friction.

[0020] In this embodiment, the spatial parasitic motion mechanism is integrally formed using CNC milling and wire cutting processes.

[0021] Working principle of the invention:

[0022] Please see Figures 1 to 8 In use, the preload of the piezoelectric ceramic is adjusted by the preload bolt 8 to ensure that the piezoelectric ceramic is in a good preload state and that the ball head 6-1 contacts the bottom surface of the motion platform 1.

[0023] Taking movement in the negative y-direction as an example, in use, this invention applies an electric field to the piezoelectric ceramic I7-1 that drives the horizontal projection extending along the y-direction. Figure 6 The voltage signal is shown. During the time interval t0-t1, the piezoelectric ceramic I7-1 elongates relatively slowly, pushing the spatial parasitic motion mechanism 6. Guided by its double parallel leaf-shaped flexible hinges 6-4, it sequentially drives the leaf-shaped flexible hinges 6-3 and X-shaped flexible hinges 6-2 to move and deform, ultimately pushing the ball head 6-1 to generate parasitic motion in the negative y-direction and the positive z-direction. Under the action of this parasitic motion, the ball head 6-1 provides a static friction force in the negative y-direction to the motion platform 1. Guided by the cross roller guides 5 in the y-direction, the motion platform 1 moves a relatively large distance L1 in the negative y-direction; as the feed displacement of the ball head 6-1 in the negative y-direction increases, the displacement in the positive z-direction also continuously increases, causing the clamping force to continuously increase, ultimately leading to a continuous increase in the static friction force. This process corresponds to the viscous motion stage.

[0024] At times t1-t2, the piezoelectric ceramic I7-1 retracts relatively quickly, and the double parallel leaf-shaped flexible hinges 6-4, 6-3, and 6-2, under their own elasticity, relatively quickly return to their initial positions and deformed states, ultimately driving the ball head 6-1 to return to its initial position relatively quickly along the positive y-direction and negative z-direction. Due to the inertia of the motion platform 1 moving along the negative y-direction during the viscous motion phase, relative sliding occurs between the ball head 6-1 and the motion platform 1, providing a sliding friction force along the positive y-direction. Guided by the cross roller guide 5 in the y-direction, the motion platform 1 moves a relatively small distance L2 along the positive y-direction. This process corresponds to the sliding motion phase.

[0025] Therefore, during the entire motion cycle from t0 to t2, the motion platform 1 moves along the negative y-direction, with a net displacement of L1-L2. By repeating the above motion cycle, the motion platform 1 can achieve a large-stroke motion along the negative y-direction.

[0026] Similar to movement in the negative y-direction, when the same input is simultaneously applied to piezoelectric ceramics II7-2 and III7-3... Figure 6 When the voltage signal shown is applied, the motion platform 1 can achieve a large stroke motion along the positive y-direction.

[0027] Similar to movement in the negative y-direction, when input to piezoelectric ceramic I7-1 and piezoelectric ceramic III7-3... Figure 7 When the voltage signal shown is applied, the motion platform 1 can achieve a large stroke motion along the positive x-direction.

[0028] Similar to movement in the negative y-direction, when input to piezoelectric ceramic I7-1 and piezoelectric ceramic II7-2... Figure 7 When the voltage signal shown is applied, the motion platform 1 can achieve a large stroke motion along the negative x-direction.

[0029] In summary, the stick-slip driven positioning platform of this invention can achieve large-stroke, high-precision motion along the x and y directions. The two sets of orthogonally arranged cross roller guides in series enable two-degree-of-freedom uncoupled motion, avoiding the direct stacking, orthogonal, and series connection of two single-degree-of-freedom stick-slip driven positioning platforms, ensuring identical dynamic characteristics, load capacity, backlash displacement, and speed along both motion directions. The piezoelectric ceramic-driven spatial parasitic motion mechanism requires only three piezoelectric ceramics to simultaneously achieve x- and y-direction drive, continuously increasing friction during the sticking process and decreasing friction during the sliding process, thus improving load capacity while reducing backlash displacement. The spatial parasitic motion mechanism can simultaneously achieve feed motion in both positive and negative x and y directions, avoiding the problem of low output force in the other direction due to only being able to achieve feed motion in either the positive or negative x or y direction, thereby improving the output force of bidirectional motion.

[0030] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A two-degree-of-freedom stick-slip driving positioning platform based on a spatial parasitic motion mechanism, comprising a base, characterized in that, Two x-direction cross roller guides are arranged in parallel on the base, a connecting frame is arranged on the two x-direction cross roller guides, two y-direction cross roller guides are arranged on the connecting frame, and a motion platform is arranged on the two y-direction cross roller guides, wherein the motion platform is driven by a spatial parasitic motion mechanism, The spatial parasitic motion mechanism is provided with three parallel branches which are distributed along the circumference, and the horizontal projection of one of the branches extends along the y direction, each of the branches is provided with an X-shaped flexible hinge, a leaf-shaped flexible hinge and a double parallel leaf-shaped flexible hinge which are arranged in series from top to bottom, the leaf-shaped flexible hinge extends upward along a 45° direction, and the plane thereof is perpendicular to the xy plane, one foot of the X-shaped flexible hinge extends along the vertical direction, and the other foot is at a 45° angle with the xy plane and is perpendicular to the leaf-shaped flexible hinge, the double parallel leaf-shaped flexible hinge is parallel to the xy plane, the upper ends of the three branches are connected in parallel to a ball head, and the lower ends are connected in parallel to a stand column, the stand column is fixed on a ceramic mounting base, each of the branches is driven by a piezoelectric ceramic, the piezoelectric ceramic is arranged vertically on the ceramic mounting base, and a pre-tightening bolt is arranged to provide a pre-tightening force, the pre-tightening bolt is connected to the ceramic mounting base, the ceramic mounting base is fixed on the base, and the ball head is in contact with the bottom surface of the motion platform.

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