Piezoelectrically driven flexible clamping mechanism with variable stiffness

Abstract

The present invention provides a piezoelectric-driven flexible clamping mechanism with variable stiffness, including a clamping unit for realizing a clamping function, and a variable stiffness unit for realizing a stiffness adjustment function. By adding a variable stiffness structure on the basis of a traditional flexible clamping mechanism, two piezoelectric ceramic drivers are used to completely separate the clamping function and the stiffness adjustment function, respectively. The first piezoelectric ceramic driver and the second piezoelectric ceramic driver can work simultaneously without affecting each other, which greatly improves the work efficiency and has good environmental interaction capabilities; the first diamond displacement amplification mechanism and the second diamond displacement amplification mechanism both use a double-beam structure instead of a traditional single-beam structure, which increases the stiffness of the output end while having a larger displacement amplification ratio; the bending deformation degree of the flexible sheet can be changed by controlling the output displacement of the second piezoelectric ceramic driver, realizing the transition of the high and low stiffness states at the jaws of the clamp fingers, and broadening the types of variable stiffness technologies.

Description

Technical Field

[0001] The invention relates to the field of micro-nano operation technology, and in particular to a piezoelectric driven flexible clamping mechanism with variable stiffness. Background Art

[0002] In recent years, with the rapid development of precision positioning, cell manipulation, microelectronic assembly and other fields, people have high requirements for the range of motion and motion accuracy of clamping mechanisms in micro-nano operations. Traditional rigid clamping mechanisms use rigid kinematic pairs to achieve the transmission or conversion of motion or force, but there are gaps in rigid kinematic pairs, which affects the accuracy of micro-nano operations. Flexible clamping mechanisms are widely used in micro-nano operations due to their integrated, frictionless and gapless characteristics.

[0003] Since the displacement is generated by its own deformation, the driver of the flexible clamping mechanism needs to have characteristics such as fast response speed and high resolution. Piezoelectric drivers are widely used to drive flexible clamping mechanisms because of their advantages of high resolution, high output stiffness and high response speed.

[0004] Traditional rigid clamping mechanisms can often only adapt to hard objects of different sizes through their opening and closing movements, and are difficult to adapt to objects with complex geometric shapes or brittle or soft textures. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a piezoelectric driven flexible clamping mechanism with variable stiffness, aiming to solve the technical problem in the prior art that traditional rigid clamping mechanisms can only adapt to hard objects of different sizes through their opening and closing movements, and are difficult to adapt to objects with complex geometric shapes or brittle and soft textures.

[0006] In order to achieve the above-mentioned object, the present invention is implemented by the following technical scheme: a piezoelectric driven flexible clamping mechanism with variable stiffness, comprising a clamping unit for realizing a clamping function, and a variable stiffness unit for realizing a stiffness adjustment function;

[0007] The clamping unit comprises a base and a clamp finger arranged in the middle of the base, the clamp finger comprises a first clamp finger and a second clamp finger arranged opposite to each other, a first rhombus displacement amplification mechanism is arranged between the first clamp finger and the second clamp finger, the bottom ends of the first clamp finger and the second clamp finger are respectively connected to the first output end and the second output end of the first rhombus displacement amplification mechanism through a rigid connecting piece, both sides of the first clamp finger and the second clamp finger are connected to the base through a flexible hinge, the first clamp finger and the second clamp finger each comprise a lower clamp finger arranged close to one side of the base, and an upper clamp finger arranged on one side of the lower clamp finger, and the flexible hinge is arranged on the lower clamp finger;

[0008] The variable stiffness unit includes a pair of flexible sheets arranged between the upper clamp fingers and the lower clamp fingers, two rigid elements arranged on both sides of the flexible sheets, and a second diamond-shaped displacement amplification mechanism arranged between the two rigid elements. The flexible sheets include a first pair of flexible sheets arranged corresponding to the first clamp fingers, and a second pair of flexible sheets arranged corresponding to the second clamp fingers. The rigid elements include a first rigid element connected to the first pair of flexible sheets, a second rigid element connected to the second pair of flexible sheets, and a third rigid element arranged between the first rigid element and the second rigid element. The second diamond-shaped displacement amplification mechanism includes a third output end connected to the third rigid element.

[0009] According to one aspect of the above technical solution, the first diamond-shaped displacement amplification mechanism and the second diamond-shaped displacement amplification mechanism are arranged in axial 90° eccentric arrangements.

[0010] According to one aspect of the above technical solution, the variable stiffness unit further includes an arc-shaped flexible hinge group respectively arranged between the first rigid element, the second rigid element and the third rigid element.

[0011] According to one aspect of the above technical solution, the first diamond-shaped displacement amplification mechanism also includes a first input end and a second input end corresponding to the two sides of the base respectively, and a first piezoelectric ceramic driver arranged between the first input end and the second input end, and the first input end, the second input end, the first output end and the second output end are connected by four first flexible hinge groups, and the first flexible hinge group includes a pair of first flexible beams arranged in parallel.

[0012] According to one aspect of the above technical solution, the angle between the first flexible beam and the first input end is 14°.

[0013] According to one aspect of the above technical solution, a first pre-tightening bolt is provided between the base and the first input end and the second input end, a first through hole corresponding to the first pre-tightening bolt is opened on the side of the base, and a first threaded hole corresponding to the first pre-tightening bolt is provided on the side of the first input end close to the base.

[0014] According to one aspect of the above technical solution, a fixing bolt is provided between the base and the workbench, and a second through hole corresponding to the fixing bolt is opened on the base.

[0015] According to one aspect of the above technical solution, the second diamond-shaped displacement amplification mechanism also includes a third input end, a fourth input end, a second piezoelectric ceramic driver arranged between the third input end and the fourth input end, and a fourth output end arranged corresponding to the third output end, and the third input end, the fourth input end, the third output end and the fourth output end are connected by four second flexible hinge groups, and the second flexible hinge groups include a pair of second flexible beams arranged in parallel.

[0016] According to one aspect of the above technical solution, the angle between the second flexible beam and the third input end is 14°.

[0017] According to one aspect of the above technical solution, the third input end and the fourth input end are respectively provided with U-shaped grooves for placing the second piezoelectric ceramic driver, and the side of the third input end is provided with a second pre-tightening bolt corresponding to the second piezoelectric ceramic driver through a second threaded hole, and the second pre-tightening bolt is arranged at intervals between the two flexible sheets of the first flexible sheet pair.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: by adding a variable stiffness structure on the basis of the traditional flexible clamping mechanism, two piezoelectric ceramic drivers are used to completely separate the clamping function and the stiffness adjustment function, and the first piezoelectric ceramic driver and the second piezoelectric ceramic driver can work simultaneously without affecting each other, which greatly improves the working efficiency and has good environmental interaction capability; the first diamond displacement amplification mechanism and the second diamond displacement amplification mechanism both adopt a double-beam structure instead of the traditional single-beam structure, which increases the stiffness of the output end while having a larger displacement amplification ratio; the degree of bending deformation of the flexible sheet can be changed by controlling the output displacement of the second piezoelectric ceramic driver, thereby realizing the transition between high and low stiffness states at the jaws of the clamp fingers, and broadening the types of variable stiffness technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a piezoelectric driven flexible clamping mechanism with variable stiffness in one embodiment of the present invention;

[0020] Figure 2 It is a schematic structural diagram of a clamping unit in one embodiment of the present invention;

[0021] Figure 3 It is a structural schematic diagram of the clamp finger in one embodiment of the present invention;

[0022] Figure 4 It is a schematic structural diagram of a variable stiffness unit in one embodiment of the present invention;

[0023] Figure 5 It is a schematic diagram of the structure of a rigid element in one embodiment of the present invention;

[0024] Figure 6 It is a structural schematic diagram of a first diamond-shaped displacement amplification mechanism in one embodiment of the present invention;

[0025] Figure 7 Schematic diagram of the structure of the second diamond-shaped displacement amplification mechanism in one embodiment of the present invention;

[0026] Figure 8 It is a schematic diagram of the assembly structure of a piezoelectric driven flexible clamping mechanism with variable stiffness in one embodiment of the present invention;

[0027] Description of main component symbols:

[0028] 1. Clamping unit; 2. Variable stiffness unit; 3. Clamp finger; 4. Rigid connector; 5. Base; 6. First through hole; 7. First rhombus displacement amplification mechanism; 8. Flexible hinge; 9. Second through hole; 10. Second rhombus displacement amplification mechanism; 11. Arc-shaped flexible hinge group; 12. Flexible sheet; 13. Rigid element; 14. Second piezoelectric ceramic driver; 15. First piezoelectric ceramic driver; 16. First pre-tightening bolt; 17. Fixing bolt; 18. Second pre-tightening bolt; 301. First clamp finger; 302. Second clamp Finger; 701, first output end; 702, first input end; 703, first threaded hole; 704, second output end; 705, first flexible hinge group; 706, second input end; 1001, third output end; 1002, third input end; 1003, second threaded hole; 1004, fourth output end; 1005, second flexible hinge group; 1006, fourth input end; 1007, U-shaped groove; 1301, first rigid element; 1302, second rigid element; 1303, third rigid element;

[0029] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0033] See also Figures 1 to 8 , shown is a piezoelectric driven flexible clamping mechanism with variable stiffness in one embodiment of the present invention, comprising a clamping unit 1 for realizing a clamping function, and a variable stiffness unit 2 for realizing a stiffness adjustment function. The clamping unit 1 is located at the lower layer and is used to realize a clamping action, and the variable stiffness unit 2 is located at the upper layer and is used to realize the adjustment of the stiffness at the jaws of the clamp finger 3.

[0034] The clamping unit 1 includes a base 5 and a clamp finger 3 arranged in the middle of the base 5, the clamp finger 3 includes a first clamp finger 301 and a second clamp finger 302 arranged opposite to each other, a first diamond-shaped displacement amplification mechanism 7 is arranged between the first clamp finger 301 and the second clamp finger 302, the bottom ends of the first clamp finger 301 and the second clamp finger 302 are respectively connected to the first output end 701 and the second output end 704 of the first diamond-shaped displacement amplification mechanism 7 through a rigid connecting member 4, both sides of the first clamp finger 301 and the second clamp finger 302 are connected to the base 5 through a flexible hinge 8, the first clamp finger 301 and the second clamp finger 302 both include a lower clamp finger 3 arranged close to one side of the base 5, and an upper clamp finger 3 arranged on one side of the lower clamp finger 3, and the flexible hinge 8 is arranged on the lower clamp finger 3.

[0035] The variable stiffness unit 2 includes a pair of flexible sheets 12 disposed between the upper and lower fingers 3, two rigid elements 13 disposed on both sides of the flexible sheets 12, and a second rhombus displacement amplification mechanism 10 disposed between the two rigid elements 13, wherein the flexible sheets 12 include a first flexible sheet pair disposed corresponding to the first fingers 301, and a second flexible sheet pair disposed corresponding to the second fingers 302, the rigid element 13 includes a first rigid element 1301 connected to the first flexible sheet pair, a second rigid element 1302 connected to the second flexible sheet pair, and a third rigid element 1303 disposed between the first rigid element 1301 and the second rigid element 1302, and the second rhombus displacement amplification mechanism 10 includes a third output terminal 1001 connected to the third rigid element 1303. The rigid elements 13 disposed horizontally on the left and right sides of the second rhombus displacement amplification mechanism 10 can ensure that the mechanism has good stability.

[0036] Furthermore, in the present embodiment, the first diamond-shaped displacement amplifying mechanism 7 also includes a first input end 702 and a second input end 706 respectively corresponding to the two sides of the base 5, and a first piezoelectric ceramic driver 15 arranged between the first input end 702 and the second input end 706, and the first input end 702, the second input end 706, the first output end 701 and the second output end 704 are connected by four first flexible hinge groups 705, and the first flexible hinge group 705 includes a pair of first flexible beams arranged in parallel.

[0037] Preferably, in this embodiment, the angle between the first flexible beam and the first input end 702 is 14°. A first pre-tightening bolt 16 is provided between the base 5 and the first input end 702 and the second input end 706. A first through hole 6 corresponding to the first pre-tightening bolt 16 is provided on the side of the base 5. A first threaded hole 703 corresponding to the first pre-tightening bolt 16 is provided on the side of the first input end 702 close to the base 5. The first rhombus displacement amplification mechanism 7 not only has a high displacement amplification ratio, but also increases the stiffness of the output end. A first threaded hole 703 is provided on the side of the first input end 702 to ensure that the first pre-tightening bolt 16 can pre-tighten the first piezoelectric ceramic driver 15 through the first threaded hole 703.

[0038] For ease of understanding, the piezoelectric-driven flexible clamping mechanism with variable stiffness is a spatial type as a whole, including two parts, the upper and lower parts. The lower layer is a clamping unit 1, wherein the first clamp finger 301 and the second clamp finger 302 are placed vertically, and the base 5 is placed horizontally on both sides of the first clamp finger 301 and the second clamp finger 302. The base 5 is provided with a second through hole 9, and the mechanism can be fixed to the end of the mechanical arm or the workbench with a fixing bolt 17. The side is provided with a first through hole 6, and the first pre-tightening bolt 16 can be used to pre-tighten the first piezoelectric ceramic driver 15; the upper layer is a variable stiffness unit 2, which is horizontally suspended above the clamping unit 1. The first rhombus displacement amplification mechanism 7 and the second rhombus displacement amplification mechanism 10 are arranged in an axial 90° eccentric manner.

[0039] Furthermore, in the present embodiment, the second diamond displacement amplification mechanism 10 also includes a third input terminal 1002, a fourth input terminal 1006, a second piezoelectric ceramic driver 14 arranged between the third input terminal 1002 and the fourth input terminal 1006, and a fourth output terminal 1004 arranged corresponding to the third output terminal 1001, and the third input terminal 1002, the fourth input terminal 1006, the third output terminal 1001 and the fourth output terminal 1004 are connected by four second flexible hinge groups 1005, and the second flexible hinge group 1005 includes a pair of second flexible beams arranged in parallel.

[0040] Preferably, in this embodiment, the angle between the second flexible beam and the third input end 1002 is 14°. The third input end 1002 and the fourth input end 1006 are respectively provided with a U-shaped groove 1007 for placing the second piezoelectric ceramic driver 14, and the side of the third input end 1002 is provided with a second pre-tightening bolt 18 corresponding to the second piezoelectric ceramic driver 14 through a second threaded hole 1003, and the second pre-tightening bolt 18 is arranged between the two flexible sheets 12 of the first flexible sheet pair in an interval manner. The side of the third input end 1002 is provided with a second threaded hole 1003 to ensure that the second pre-tightening bolt 18 can pre-tighten the second piezoelectric ceramic driver 14 through the second threaded hole 1003. The distance between the two flexible sheets 12 is slightly larger than the diameter of the second pre-tightening bolt 18 to ensure that the flexible sheet 12 does not contact the second pre-tightening bolt 18 when bending. The width of the above-mentioned U-shaped groove 1007 is preferably 5mm.

[0041] The first piezoelectric ceramic driver 15 is used to control the first finger 301 and the second finger 302 of the clamping unit 1 to move closer to or farther from each other, thereby achieving the action of clamping and unloading the clamped object; the second piezoelectric ceramic driver 14 is used to control the flexible sheet 12 of the variable stiffness unit 2 to bend and deform, so that the vertical stiffness of the finger 3 changes, thereby achieving the change of high and low stiffness at the jaws of the finger 3. The first piezoelectric ceramic driver 15 and the second piezoelectric ceramic driver 14 can work simultaneously without affecting each other, and greatly improve the work efficiency.

[0042] In addition, in this embodiment, the variable stiffness unit 2 further includes an arc-shaped flexible hinge group 11 respectively arranged between the first rigid element 1301 , the second rigid element 1302 and the third rigid element 1303 to reduce the coupling effect between the variable stiffness unit 2 and the clamping unit 1 .

[0043] In some application scenarios of the present embodiment, when the first piezoelectric ceramic driver 15 gives the first diamond displacement amplifying mechanism 7 an input displacement, the distance between the first input end 702 and the second input end 706 of the first diamond displacement amplifying mechanism 7 increases, and accordingly, the distance between the first output end 701 and the second output end 704 decreases, the first clamp finger 301 and the second clamp finger 302 approach each other, and the clamping mechanism completes the clamping action; when the input displacement on the first piezoelectric ceramic driver 15 is removed, the first diamond displacement amplifying mechanism 7 returns to its original state, the distance between the first input end 702 and the second input end 706 decreases, and accordingly, the distance between the first output end 701 and the second output end 704 increases, the first clamp finger 301 and the second clamp finger 302 move away from each other, and the clamping mechanism completes the unloading action.

[0044] When the second piezoelectric ceramic driver 14 gives an input displacement to the second diamond displacement amplifier mechanism 10, the distance between the third input and fourth input terminals 1006 of the second diamond displacement amplifier mechanism 10 increases, and correspondingly, the distance between the third output terminal 1001 and the fourth output terminal 1004 decreases. The two rigid elements 13 squeeze the two groups of flexible sheets 12, causing them to bend and deform, causing the vertical stiffness of the pliers 3 to change, thereby achieving a transition from high to low stiffness at the jaws of the pliers 3.

[0045] In summary, the piezoelectric-driven flexible clamping mechanism with variable stiffness in the above-mentioned embodiments of the present invention, by adding a variable stiffness structure on the basis of the traditional flexible clamping mechanism, uses two piezoelectric ceramic drivers to completely separate the clamping function and the stiffness adjustment function, and the first piezoelectric ceramic driver 15 and the second piezoelectric ceramic driver 14 can work simultaneously without affecting each other, which greatly improves the working efficiency and has good environmental interaction capability; the first diamond displacement amplification mechanism 7 and the second diamond displacement amplification mechanism 10 both adopt a double-beam structure instead of the traditional single-beam structure, which increases the stiffness of the output end while having a larger displacement amplification ratio; the bending deformation degree of the flexible sheet 12 can be changed by controlling the output displacement of the second piezoelectric ceramic driver 14, thereby realizing the transition between high and low stiffness states at the jaws of the clamp fingers 3, and broadening the types of variable stiffness technologies.

[0046] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A piezoelectrically driven flexible clamping mechanism with variable stiffness, characterized in that: It includes a clamping unit for realizing a clamping function, and a variable stiffness unit for realizing a stiffness adjustment function; The clamping unit comprises a base and a clamp finger arranged in the middle of the base, the clamp finger comprises a first clamp finger and a second clamp finger arranged opposite to each other, a first rhombus displacement amplification mechanism is arranged between the first clamp finger and the second clamp finger, the bottom ends of the first clamp finger and the second clamp finger are respectively connected to the first output end and the second output end of the first rhombus displacement amplification mechanism through a rigid connecting piece, both sides of the first clamp finger and the second clamp finger are connected to the base through a flexible hinge, the first clamp finger and the second clamp finger each comprise a lower clamp finger arranged close to one side of the base, and an upper clamp finger arranged on one side of the lower clamp finger, and the flexible hinge is arranged on the lower clamp finger; The variable stiffness unit includes a pair of flexible sheets arranged between the upper pliers and the lower pliers, two rigid elements arranged on both sides of the flexible sheets, and a second rhombus displacement amplification mechanism arranged between the two rigid elements, the flexible sheets include a first flexible sheet pair arranged corresponding to the first pliers, and a second flexible sheet pair arranged corresponding to the second pliers, the rigid elements include a first rigid element connected to the first flexible sheet pair, a second rigid element connected to the second flexible sheet pair, and a third rigid element arranged between the first rigid element and the second rigid element, and the second rhombus displacement amplification mechanism includes a third output terminal connected to the third rigid element; The first rhombus displacement amplifying mechanism and the second rhombus displacement amplifying mechanism are arranged in different planes at 90° in the axial direction; The variable stiffness unit further comprises an arc-shaped flexible hinge group respectively arranged between the first rigid element, the second rigid element and the third rigid element; The first diamond-shaped displacement amplification mechanism further includes a first input end and a second input end respectively corresponding to two sides of the base, and a first piezoelectric ceramic driver arranged between the first input end and the second input end, the first input end, the second input end, the first output end and the second output end are connected by four first flexible hinge groups, and the first flexible hinge group includes a pair of first flexible beams arranged in parallel; The second diamond-shaped displacement amplification mechanism also includes a third input end, a fourth input end, a second piezoelectric ceramic driver arranged between the third input end and the fourth input end, and a fourth output end arranged corresponding to the third output end. The third input end, the fourth input end, the third output end and the fourth output end are connected by four second flexible hinge groups, and the second flexible hinge groups include a pair of second flexible beams arranged in parallel.

2. The piezoelectric driven flexible clamping mechanism with variable stiffness according to claim 1, characterized in that: The included angle between the first flexible beam and the first input end is 14°.

3. The piezoelectric driven flexible clamping mechanism with variable stiffness according to claim 1, characterized in that: A first pre-tightening bolt is provided between the base and the first input end and the second input end, a first through hole corresponding to the first pre-tightening bolt is opened on the side of the base, and a first threaded hole corresponding to the first pre-tightening bolt is provided on the side of the first input end close to the base.

4. The piezoelectric driven flexible clamping mechanism with variable stiffness according to claim 1, characterized in that: A fixing bolt is arranged between the base and the workbench, and a second through hole corresponding to the fixing bolt is opened on the base.

5. The piezoelectric driven flexible clamping mechanism with variable stiffness according to claim 1, characterized in that: The included angle between the second flexible beam and the third input end is 14°.

6. The piezoelectric driven flexible clamping mechanism with variable stiffness according to claim 1, characterized in that: The third input end and the fourth input end are respectively provided with U-shaped grooves for placing the second piezoelectric ceramic driver, and the side of the third input end is provided with a second pre-tightening bolt corresponding to the second piezoelectric ceramic driver through a second threaded hole, and the second pre-tightening bolt is arranged at intervals between the two flexible sheets of the first flexible sheet pair.

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