A spatial helical compliant mechanism with variable stiffness characteristics

Abstract

The application discloses a spatial spiral compliance mechanism with a variable stiffness characteristic, comprising a variable stiffness component, a bending component and a fixed base, wherein the variable stiffness component comprises a rigid element, two first leaf-shaped flexible hinges and a variable stiffness module, the two first leaf-shaped flexible hinges are oppositely arranged, and opposite ends of the two first leaf-shaped flexible hinges are respectively connected with the rigid element and the fixed base; the rigid element, the two first leaf-shaped flexible hinges and the fixed base enclose a containing space, the containing space is provided with the variable stiffness module, the fixed base is provided with a containing groove, the bending component is connected with the inner wall of the containing groove, and opposite ends of the variable stiffness module are respectively connected with the rigid element and the bending component; the rotation angle of the variable stiffness module is controlled by input displacement of a driver, the continuous and accurate adjustment of the lateral stiffness of the rigid element can be realized, the variable stiffness module can be quickly adjusted to a suitable stiffness value according to different working requirements, and the adaptability of the spatial spiral compliance device is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compliant mechanism, in particular to a spatial spiral compliant mechanism with variable stiffness characteristics. BACKGROUND

[0002] In recent years, with the rapid development of micro-nano technology and the revolutionary changes it has triggered in many fields such as manufacturing, information, materials, biology, medicine and national defense, compliant mechanisms have been widely used in high-precision fields such as microelectronic and optoelectronic device precision microfabrication and microoperation, biomedical engineering, which require positioning accuracy of sub-micron or even nanometer level.

[0003] Based on the working principle of realizing displacement output through self-elastic deformation, compliant mechanisms have strict requirements for the response speed and resolution of the driver. Piezoelectric drivers have become the preferred solution for driving compliant mechanisms due to their outstanding high-resolution characteristics, excellent output stiffness performance and fast dynamic response capabilities.

[0004] Traditional mechanical systems maintain constant stiffness characteristics after parameter determination, resulting in fixed and unchangeable mechanism performance. This characteristic significantly limits its applicable working range. SUMMARY

[0005] In view of the above situation, a spatial spiral compliant mechanism with variable stiffness characteristics is provided to solve the technical problems mentioned in the background.

[0006] A spatial spiral compliant mechanism with variable stiffness characteristics, comprising a variable stiffness component, a bending component and a fixed base, the variable stiffness component comprising a rigid element, two first leaf-shaped flexible hinges and a variable stiffness module, the two first leaf-shaped flexible hinges being oppositely arranged, the opposite ends of the two first leaf-shaped flexible hinges being connected with the rigid element and the fixed base respectively, the rigid element, the two first leaf-shaped flexible hinges and the fixed base forming an accommodating space, the variable stiffness module being provided in the accommodating space, the fixed base being provided with an accommodating groove, the bending component being connected with the inner wall of the accommodating groove, the opposite ends of the variable stiffness module being connected with the rigid element and the bending component respectively, the accommodating groove being provided with a driver, the driver being located at one end of the bending component away from the variable stiffness module, the driver driving the bending component to drive the variable stiffness module to rotate in the axial direction, the rigid element, the variable stiffness module, the bending component and the driver being coaxially arranged.

[0007] Compared with the prior art, the present application has the following advantages:

[0008] 1. Flexible stiffness adjustment capability: By driving the input displacement control of the variable stiffness module, the lateral stiffness of the rigid element can be continuously and accurately adjusted, and the appropriate stiffness value can be quickly adjusted according to different working requirements, greatly improving the adaptability of the spatial spiral compliant device.

[0009] 2. Compact and simple structure: The variable stiffness module design of the present application has a compact overall structure, which can greatly meet the variable stiffness requirement of the spatial spiral compliant device under complex working conditions, and has good environmental interaction capability.

[0010] 3. High stability and precision: The careful design of the variable stiffness assembly, the bending assembly and the fixed base ensures the stability and precision of the spatial spiral compliant device during operation, reduces the error caused by structural deformation and vibration, and can realize high-precision displacement transmission.

[0011] Further, the variable stiffness module comprises a first variable stiffness unit, a second leaf-shaped flexible hinge and a second variable stiffness unit, the opposite ends of the second leaf-shaped flexible hinge are connected with the first variable stiffness unit and the second variable stiffness unit respectively, the end of the first variable stiffness unit away from the second leaf-shaped flexible hinge is connected with the rigid element, and the end of the second variable stiffness unit away from the second leaf-shaped flexible hinge is connected with the bending assembly.

[0012] Further, the first variable stiffness unit comprises a first connecting piece, a plurality of first spiral beams and a second connecting piece, a plurality of first spiral beams are arranged at intervals and located between the first connecting piece and the second connecting piece, the opposite ends of a plurality of first spiral beams are connected with the circumferential edge of the end face of the first connecting piece and the second connecting piece respectively, a plurality of first spiral beams are arranged in axial torsion, the end of the first connecting piece away from the first spiral beam is connected with the rigid element, and the end of the second connecting piece away from the first spiral beam is connected with the second leaf-shaped flexible hinge.

[0013] Further, the second variable stiffness unit comprises a third connecting piece, a plurality of second spiral beams and a fourth connecting piece, a plurality of second spiral beams are arranged at intervals and located between the third connecting piece and the fourth connecting piece, the opposite ends of a plurality of second spiral beams are connected with the circumferential edge of the end face of the third connecting piece and the fourth connecting piece respectively, a plurality of second spiral beams are arranged in axial torsion, the end of the third connecting piece away from the second spiral beam is connected with the second leaf-shaped flexible hinge, and the end of the fourth connecting piece away from the second spiral beam is connected with the bending assembly.

[0014] Further, the relationship between the displacement of the driver and the lateral stiffness of the rigid element is:

[0015]

[0016] wherein, , is the lateral stiffness of the rigid element, is the elastic modulus of the spatial spiral compliant mechanism with variable stiffness characteristics, is the displacement of the driver.

[0017] Further, the first spiral beam and the second spiral beam are both in spiral shape, and the spiral directions are opposite, and the cross sections of the first spiral beam and the second spiral beam are both rectangular.

[0018] Further, the bending assembly comprises a left bending beam, a main piece and a right bending beam, opposite ends of the main piece are fixedly connected with the left bending beam and the right bending beam respectively, one end of the left bending beam away from the main piece is connected with the inner wall of the accommodating groove, one end of the right bending beam away from the main piece is connected with the inner wall of the accommodating groove, and opposite end faces of the main piece are connected with the driver and the fourth connecting piece respectively.

[0019] Further, a plurality of through holes are arranged on the fixed base, and the through holes are used for fixing the fixed base and a workbench.

[0020] Further, one end of the fixed base away from the bending assembly is provided with a threaded hole, the threaded hole is communicated with the accommodating groove, a locking bolt is arranged in the threaded hole, one end of the locking bolt extends into the accommodating groove and abuts against the driver.

[0021] Further, the driver, the main piece, the first connecting piece, the second connecting piece, the second leaf-shaped flexible hinge, the third connecting piece, the fourth connecting piece and the rigid element are coaxially arranged. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 Structure diagram of the spatial spiral compliant mechanism with variable stiffness characteristics of the present application Figure 1

[0024] Figure 2 Structure diagram of the spatial spiral compliant mechanism with variable stiffness characteristics of the present application Figure 2 ​​​

[0025] Figure 3 Structure diagram of the variable stiffness module of the present application;

[0026] Figure 4 First variable stiffness unit of the first variable stiffness unit of the present application;

[0027] Figure 5 First variable stiffness unit of the second variable stiffness unit of the present application;

[0028] Figure 6 Structure diagram of the bending assembly of the present application;

[0029] Figure 7 Structure diagram of the fixed base of the present application.

[0030] In the figure: 1, variable stiffness assembly; 11, rigid element; 12, first leaf-shaped flexible hinge; 13, variable stiffness module; 131, first variable stiffness unit; 1311, first connecting piece; 1312, first spiral beam; 1313, second connecting piece; 132, second leaf-shaped flexible hinge; 133, second variable stiffness unit; 1331, third connecting piece; 1332, second spiral beam; 1333, fourth connecting piece; 2, bending assembly; 21, left bending beam; 22, main piece; 23, right bending beam; 3, driver; 4, fixed base; 41, accommodating groove; 42, through hole; 43, threaded hole; 5, accommodating space; 6, fixing bolt; 7, locking bolt.

[0031] The embodiments of the present application will be further described below with reference to the drawings. DETAILED DESCRIPTION

[0032] Embodiments of the present application will be described in detail below with reference to the drawings, in which the same or similar components are denoted by the same or similar reference numerals throughout, and wherein the embodiments described below are exemplary and are intended to explain the embodiments of the present application, and should not be understood as limiting the present application.

[0033] In the description of the embodiments of the present application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be understood as limiting the present application.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] Please see Figures 1 to 7 A spatial helical compliant mechanism with variable stiffness characteristics includes a variable stiffness component 1, a bending component 2, and a fixed base 4.

[0036] Specifically, the variable stiffness component 1 includes a rigid element 11, two first leaf-shaped flexible hinges 12, and a variable stiffness module 13. The two first leaf-shaped flexible hinges 12 are arranged opposite to each other, and their opposite ends are respectively connected to the rigid element 11 and the fixed base 4. The rigid element 11, the two first leaf-shaped flexible hinges 12, and the fixed base 4 enclose a receiving space 5. The variable stiffness module 13 is provided in the receiving space 5. Its opposite ends are respectively connected to the rigid element 11 and the bending component 2. The variable stiffness module 13 includes a first variable stiffness unit 131 and a second leaf-shaped flexible hinge. The first variable stiffness unit 132 and the second variable stiffness unit 133 are respectively connected to the first variable stiffness unit 131 and the second variable stiffness unit 133 at opposite ends. The end of the first variable stiffness unit 131 facing away from the second variable stiffness unit 132 is connected to the rigid element 11. The end of the second variable stiffness unit 133 facing away from the second variable stiffness unit 132 is connected to the bending component 2. The main function of the first variable stiffness unit 12 is to restrict the axial movement of the rigid element 11 and ensure the effectiveness of the variable stiffness module 13. The accommodating space 5 provides installation and torsional space for the variable stiffness module 13.

[0037] The first variable stiffness unit 131 includes a first connector 1311, a plurality of first helical beams 1312 and a second connector 1313. The plurality of first helical beams 1312 are evenly distributed between the first connector 1311 and the second connector 1313. The two opposite ends of the plurality of first helical beams 1312 are respectively connected to the periphery of the end faces of the first connector 1311 and the second connector 1313. The plurality of first helical beams 1312 are twisted in the axial direction. The end of the first connector 1311 facing away from the first helical beam 1312 is connected to the rigid element 11. The end of the second connector 1313 facing away from the first helical beam 1312 is connected to the second leaf-shaped flexible hinge 132.

[0038] Specifically, the second variable stiffness unit 133 includes a third connector 1331, multiple second helical beams 1332, and a fourth connector 1333. The multiple second helical beams 1332 are evenly distributed between the third connector 1331 and the fourth connector 1333. The two opposite ends of the multiple second helical beams 1332 are respectively connected to the periphery of the end faces of the third connector 1331 and the fourth connector 1333. The multiple second helical beams 1332 are torsionally arranged along the axial direction. One end of the third connector 1331 facing away from the second helical beams 1332 is connected to the second leaf-shaped flexible hinge 132. One end of the fourth connector 1333 facing away from the second helical beams 1332 is connected to the main component 22.

[0039] Furthermore, both the first helical beam 1312 and the second helical beam 1332 are helical in shape and in opposite directions, and both the cross-sections of the first helical beam 1312 and the second helical beam 1332 are rectangular.

[0040] It should be noted that, based on the variable stiffness principle of the spatial spiral structure, the driver 3 realizes the input displacement through the connecting wire, which pushes the bending component 2 to squeeze towards the variable stiffness module 13. Since the rigid element 11, the first leaf-shaped flexible hinge 12 and the fixed base 4 do not deform relative to each other, the first spiral beam 1312 and the second spiral beam 1332 deform and twist. As a result, the first variable stiffness unit 131 and the second variable stiffness unit 133 approach each other along the axial direction and are compressed and deformed, which drives the second leaf-shaped flexible hinge 132 to rotate, thereby realizing the effective adjustment of the lateral stiffness of the rigid element 11. In this embodiment, there are six first helical beams 1312 and six second helical beams 1332. The cross-section of the first helical beam 1312 and the second helical beam 1332 is a rectangle with a length of 0.8 mm and a width of 1.6 mm. The helix length of both is 9.24 mm, the helix angle is 77°, the pitch is 67 mm, and the helix radius is 3.6 mm. The cross-section of the first leaf-shaped flexible hinge 12 is a rectangle with a length of 1 mm and a width of 12 mm, and the height is 54 mm. The cross-section of the second leaf-shaped flexible hinge 132 is a rectangle with a length of 1.1 mm and a width of 8.8 mm, and the height is 24 mm. This design enables the first variable stiffness unit 131 and the second variable stiffness unit 133 to generate large radial deformation when subjected to axial pressure, providing sufficient power for the rotation of the second leaf-shaped flexible hinge 132, thereby expanding the range of stiffness variation. During the process of the first variable stiffness unit 131 and the second variable stiffness unit 133 approaching each other along the axial direction and undergoing compression deformation, the spiral directions of the first helical beam 1312 and the second helical beam 1332 are set opposite, so that both ends of the second leaf-shaped flexible hinge 132 rotate in one direction, avoiding torsional deformation of the second leaf-shaped flexible hinge 132.

[0041] Specifically, the bending assembly 2 includes a left bending beam 21, a main member 22, and a right bending beam 23. The two opposite ends of the main member 22 are fixed to the left bending beam 21 and the right bending beam 23, respectively. The end of the left bending beam 21 facing away from the main member 22 is connected to the inner wall of the receiving groove 41, and the end of the right bending beam 23 facing away from the main member 22 is connected to the inner wall of the receiving groove 41. The two opposite ends of the main member 22 are connected to the driver 3 and the fourth connector 1333, respectively. The driver 3 inputs displacement onto the main member 22, and the main member 22 presses against the end face of the fourth connector 1333. Meanwhile, the left bending beam 21 and the right bending beam 23 remain connected to the receiving groove 41, and the main member 22 stably transmits the displacement output by the driver 3.

[0042] Specifically, the relationship between the displacement of the actuator 3 and the lateral stiffness of the rigid element 11 is as follows:

[0043]

[0044] in, ( , ) represents the lateral stiffness of rigid element 11. The elastic modulus of a spatial helical compliant mechanism with variable stiffness characteristics. This represents the displacement of driver 3.

[0045] In this embodiment, the variable stiffness component 1, the bending component 2 and the fixed base 4 are all made of 7075 aluminum alloy with an elastic modulus of 71 GPa. The actuator 3 is a piezoelectric ceramic actuator with an input displacement range of 0 mm to 1 mm. According to the above relationship, the lateral stiffness of the rigid element 11 varies from 6.29 N / mm to 51.57 N / mm. When the driver 3 gives the main component 22 an input displacement, in this embodiment, the input displacement of the driver 3 is 0.6 mm. The first connector 1311 and the second connector 1313 in the first variable stiffness unit 131 approach each other along the axial direction, and the third connector 1331 and the fourth connector 1333 in the second variable stiffness unit 133 approach each other along the axial direction, so that the first helical beam 1312 and the second helical beam 1332 are compressed and deformed along the axial direction. The second connector 1313 and the third connector 1331 rotate and drive the second leaf-shaped flexible hinge 132 to rotate, thereby changing the lateral stiffness of the rigid element 11. The lateral stiffness of the rigid element 11 is 23.17 N / mm.

[0046] Specifically, the fixed base 4 is provided with a receiving groove 41, and the receiving groove 41 is provided with a driver 3. The driver 3 is located at the end of the bending component 2 facing away from the variable stiffness module 13. The driver 3 drives the bending component 2 to rotate the variable stiffness module 13 in the axial direction. The fixed base 4 is provided with multiple through holes 42, and fixing bolts 6 are provided in the through holes 42. The fixed base 4 is fixed to the worktable by fixing bolts 6. The end of the fixed base 4 facing away from the bending component 2 is provided with a threaded hole 43, which communicates with the receiving groove 41. A locking bolt 7 is provided in the threaded hole 43. One end of the locking bolt 7 extends into the receiving groove 41 and abuts against the driver 3. The driver 3 is used as a device for input displacement. The size of the receiving groove 41 matches the driver 3 to ensure its installation accuracy and stability. The driver 3 is locked by locking bolt 7 to ensure the reliability, stability and accuracy of its connection. The fixing bolt 6 ensures the stable connection between the entire fixed base 4 and the worktable, so that it is in a stable state during operation.

[0047] Specifically, the driver 3, main component 22, first connector 1311, second connector 1313, second leaf-shaped flexible hinge 132, third connector 1331, fourth connector 1333 and rigid element 11 are coaxially arranged to ensure the displacement transmission effect and avoid deviation.

[0048] This invention controls the rotation angle of the variable stiffness module 13 by inputting displacement through the driver 3, enabling continuous and precise adjustment of the lateral stiffness of the rigid element 11. It can quickly adjust to a suitable stiffness value according to different working requirements, greatly improving the adaptability of the spatial helical compliant device. The design of the variable stiffness module 13 results in a compact overall structure, which can greatly meet the demand for variable stiffness in complex working conditions and has good environmental interaction capabilities. The careful design of the variable stiffness module 13, bending component 2, rigid element 11, and fixed base 4 ensures the stability and accuracy of the spatial helical compliant device during operation, reduces errors caused by structural deformation and vibration, and enables high-precision displacement transmission.

[0049] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A spatial helical compliant mechanism with variable stiffness characteristics, characterized in that: The device includes a variable stiffness component, a bending component, and a fixed base. The variable stiffness component includes a rigid element, two first leaf-shaped flexible hinges, and a variable stiffness module. The two first leaf-shaped flexible hinges are arranged opposite each other, and their opposite ends are respectively connected to the rigid element and the fixed base. The rigid element, the two first leaf-shaped flexible hinges, and the fixed base enclose a receiving space. The variable stiffness module is disposed within the receiving space. The fixed base has a receiving groove. The bending component is connected to the inner wall of the receiving groove. The opposite ends of the variable stiffness module are respectively connected to the rigid element and the bending component. A driver is disposed within the receiving groove. The driver is located at the end of the bending component facing away from the variable stiffness module. The driver is used to drive the bending component to rotate the variable stiffness module axially. The rigid element, the variable stiffness module, the bending component, and the driver are coaxially arranged. The variable stiffness module includes a first variable stiffness unit, a second leaf-shaped flexible hinge, and a second variable stiffness unit. The two opposite ends of the second leaf-shaped flexible hinge are respectively connected to the first variable stiffness unit and the second variable stiffness unit. The end of the first variable stiffness unit facing away from the second leaf-shaped flexible hinge is connected to the rigid element, and the end of the second variable stiffness unit facing away from the second leaf-shaped flexible hinge is connected to the bending component. The driver pushes the bending component to press against the variable stiffness module, thereby causing the first and second variable stiffness units to move closer to each other along the axial direction and compress and deform, and driving the second leaf-shaped flexible hinge to rotate, thereby achieving effective adjustment of the lateral stiffness of the rigid element.

2. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 1, characterized in that: The first variable stiffness unit includes a first connector, a plurality of first helical beams and a second connector. The plurality of first helical beams are evenly distributed between the first connector and the second connector. The two opposite ends of the plurality of first helical beams are respectively connected to the periphery of the end faces of the first connector and the second connector. The plurality of first helical beams are twisted along the axial direction. The end of the first connector facing away from the first helical beam is connected to the rigid element. The end of the second connector facing away from the first helical beam is connected to the second leaf-shaped flexible hinge.

3. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 2, characterized in that: The second variable stiffness unit includes a third connector, a plurality of second helical beams, and a fourth connector. The plurality of second helical beams are evenly distributed between the third connector and the fourth connector. The two opposite ends of the plurality of second helical beams are respectively connected to the periphery of the end faces of the third connector and the fourth connector. The plurality of second helical beams are twisted along the axial direction. The end of the third connector facing away from the second helical beams is connected to the second leaf-shaped flexible hinge. The end of the fourth connector facing away from the second helical beams is connected to the bending component.

4. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 1, characterized in that: The relationship between the displacement of the actuator and the lateral stiffness of the rigid element is as follows: in, ( , ) represents the lateral stiffness of the rigid element. The elastic modulus of a spatial helical compliant mechanism with variable stiffness characteristics. This represents the displacement of the driver.

5. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 3, characterized in that: Both the first and second spiral beams are spiral in shape and in opposite directions. The cross-sections of both the first and second spiral beams are rectangular.

6. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 3, characterized in that: The bending assembly includes a left bending beam, a main component, and a right bending beam. The two opposite ends of the main component are fixedly connected to the left bending beam and the right bending beam, respectively. The end of the left bending beam facing away from the main component is connected to the inner wall of the receiving groove, and the end of the right bending beam facing away from the main component is connected to the inner wall of the receiving groove. The two opposite ends of the main component are connected to the driver and the fourth connector, respectively.

7. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 1, characterized in that: The fixed base is provided with several through holes, which are used to fix the fixed base to the worktable.

8. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 7, characterized in that: The fixed base has a threaded hole at one end facing away from the bending component. The threaded hole communicates with the receiving groove. A locking bolt is provided in the threaded hole. One end of the locking bolt extends into the receiving groove and abuts against the driver.

9. The spatial helical compliant mechanism with variable stiffness characteristics according to claim 6, characterized in that: The driver, the main component, the first connector, the second connector, the second leaf-shaped flexible hinge, the third connector, the fourth connector, and the rigid element are coaxially arranged.

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