A stick-slip driven variable stiffness compliant mechanism with lockable mobility

Abstract

The utility model discloses a kind of stick-slip drive variable stiffness compliance mechanism with lockable movement, comprising: variable stiffness unit and locking unit, variable stiffness unit is located in the left and right parts of mechanism, by drive mechanism group, leaf spring and base constitute, drive mechanism group generates elongation deformation by piezoelectric stack, via displacement amplification mechanism drive leaf spring displacement, realize variable stiffness function;Locking unit is located in the middle part of mechanism, by a composite bridge type compliance mechanism, the compliance mechanism can generate the required input / output stiffness, to transmit the powerful force for high load locking.The utility model adopts piezoelectric stack to realize displacement locking function and stiffness adjusting function respectively, compared with traditional flexible variable stiffness mechanism, the mechanism adopts integrated design, can freely and smoothly change stiffness, and easily keep stiffness stable, to significantly improve work efficiency, with excellent environmental interaction ability, suitable for the case needing accurate control and stable operation.

Description

Technical Field

[0001] This utility model relates to the field of micro-nano manipulation technology, specifically to a stick-slip driven variable stiffness compliant mechanism with lockable movement. Background Technology

[0002] A variable stiffness mechanism is a mechanical system or device that can actively or passively change its structural stiffness (i.e., its ability to resist deformation). Simply put, it can become "rigid" or "soft" as needed, just like human muscles. Its core value lies in "customizing" stiffness on demand, enabling a mechanism to adapt to a variety of different or even contradictory task requirements.

[0003] With the rapid development of micro- and nano-technology, the requirements for micro- and nano-manipulation mechanisms are becoming increasingly stringent. Traditional variable stiffness mechanisms often only allow for changes in stiffness by adjusting structural parameters, resulting in complex operations and a limited range of stiffness variations. At the micro- and nano-scale, they often suffer from insufficient positioning accuracy and low efficiency in stiffness variation, making it difficult to meet the demands for high-precision and high-efficiency micro- and nano-manipulation. Utility Model Content In view of the shortcomings of the existing technology, the main purpose of this utility model is to provide a stick-slip driven variable stiffness compliant mechanism with lockable movement, which aims to solve the problems of low stiffness change accuracy and low change efficiency of traditional variable stiffness mechanisms.

[0004] To achieve the above objectives, the embodiments of this utility model are implemented through the following technical solutions: a base, a locking unit, and a variable stiffness unit. The base includes a first rod and a second rod and a third rod connected to opposite ends of the first rod. Two slide rails are provided on the side of the first rod facing the second rod. The locking unit includes a composite bridge-type compliant component, which is slidably connected between the two slide rails. A first piezoelectric stack is provided inside the composite bridge-type compliant component to restrict the sliding of the composite bridge-type compliant component within the slide rails. The variable stiffness unit includes a leaf spring and a driving assembly. The driving assembly includes a first driving mechanism and a second driving mechanism. The opposing sides of the second rod and the third rod are respectively rotatably connected to the... A first driving mechanism and a second driving mechanism are provided. One end of the composite bridge compliant component is connected to the leaf spring. The end of the leaf spring facing away from the composite bridge compliant component is clamped between the first driving mechanism and the second driving mechanism. A limiting rod is provided on the facing side of the second rod and the third rod. The limiting rod is located between the first rod and the component. The end of the leaf spring facing away from the composite bridge compliant component is clamped between the two limiting rods. One of the limiting rods, the third rod, the leaf spring and the first driving mechanism form a first cavity. The other limiting rod, the second rod, the leaf spring and the second driving mechanism form a second cavity. A second piezoelectric stack is provided in the first cavity and a third piezoelectric stack is provided in the second cavity.

[0005] Compared with existing technologies, the advantages of this invention are as follows: the variable stiffness unit, through the synergistic action of the drive mechanism and the leaf spring, can continuously and smoothly adjust the stiffness to meet the stiffness requirements of different operations. The locking unit employs a composite bridge-type compliant mechanism, which can generate the required input / output stiffness, ensuring stable locking under high loads and guaranteeing the reliability of the mechanism. Furthermore, this mechanism uses three piezoelectric stacks to achieve displacement locking and stiffness adjustment functions respectively. Compared with traditional flexible variable stiffness mechanisms, it has advantages such as integrated design, simple operation, smooth stiffness changes, and ease of maintaining stiffness stability. These characteristics make this mechanism widely applicable in the field of micro-nano manipulation technology, especially in applications requiring high-precision and high-efficiency operation.

[0006] Furthermore, the composite bridge compliant component includes a first fixed block, a second fixed block, a first telescopic block, and a second telescopic block. The first fixed block and the second fixed block are arranged opposite to each other. The first telescopic block and the second telescopic block are arranged between the first fixed block and the second fixed block. The opposite ends of the first telescopic block are connected to the first fixed block and the second fixed block respectively by two first flexible inclined beams. The opposite ends of the second telescopic block are connected to the first fixed block and the second fixed block respectively by two second flexible inclined beams. The first fixed block, the second fixed block, the first telescopic block, the second telescopic block, the two first flexible inclined beams, and the two second flexible inclined beams enclose a receiving cavity, and the first piezoelectric stack is arranged inside the receiving cavity.

[0007] Furthermore, the locking unit also includes a fixing structure, which includes a first plate and a second plate. The end of the composite bridge flexible component facing the leaf spring is connected to the first plate and the second plate. A first clamping space is formed between the first plate and the second plate. One end of the leaf spring is placed in the first clamping space. A first through hole perpendicular to the leaf spring is opened on both the first plate and the second plate. An opening adapted to the first through hole is opened on the leaf spring. A fixing pin is provided in the first through hole to fix the leaf spring to the first plate and the second plate.

[0008] Furthermore, both the first flexible inclined beam and the second flexible inclined beam have a through second hole.

[0009] Furthermore, the first driving mechanism includes a first hinge and a first driving foot. The first driving foot is connected to the third rod through the first hinge. One end of the first driving foot facing away from the first hinge abuts against the leaf spring. The two opposite ends of the second piezoelectric stack abut against the limiting rod and the first driving foot, respectively.

[0010] Furthermore, the first drive foot includes an extension rod and a bending rod. One end of the extension rod is connected to the first hinge, and the end of the extension rod facing away from the first hinge is connected to the bending rod. The end of the bending rod facing away from the extension rod extends in the opposite direction from the limiting rod along the extension rod. Attached Figure Description

[0011] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a three-dimensional structural diagram of a lockable and movable stick-slip driven variable stiffness compliant mechanism according to an embodiment of the present utility model. Figure 2This is a schematic diagram of the locking unit structure of a lockable and movable stick-slip driven variable stiffness compliant mechanism according to an embodiment of the present utility model. Figure 3 This is a schematic diagram of a composite bridge mechanism with a lockable and movable stick-slip driven variable stiffness compliant mechanism according to an embodiment of the present invention. Figure 4 This is a schematic diagram of a variable stiffness unit structure with a lockable and movable stick-slip driven variable stiffness compliant mechanism according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the overall assembly structure of a lockable and movable stick-slip driven variable stiffness compliant mechanism according to an embodiment of the present invention. In the diagram: 1. Locking unit; 11. Composite bridge compliant assembly; 111. First telescopic block; 112. First fixing block; 113. Second telescopic block; 114. Second fixing block; 115. First flexible inclined beam; 116. Second flexible inclined beam; 12. Fixing structure; 121. Fixing pin; 122. First plate; 123. Second plate; 124. First through hole; 2. Variable stiffness unit; 21. Leaf spring; 22. First drive mechanism; 23. First hinge; 24. 1. First driving foot; 241. Extension rod; 242. Bending rod; 25. Second driving mechanism; 26. Second driving foot; 27. Second hinge; 3. Base; 31. First rod; 32. Second rod; 33. Limiting rod; 34. Slide rail; 35. Third rod; 4. Fixing bolt; 5. First piezoelectric stack; 51. First wedge; 6. Second piezoelectric stack; 61. Second wedge; 7. Third piezoelectric stack; 71. Third wedge; 8. Bolt hole; 9. Bolt. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the scope described herein. Rather, the present invention covers any substitutions, modifications, equivalent methods, and schemes made within the spirit and scope of the present invention as defined in the claims. To provide the public with a better understanding of the present invention, some specific details are described in detail below.

[0013] Please see Figures 1 to 5This utility model provides a lockable, movable stick-slip driven variable stiffness compliant mechanism, including a locking unit 1, a variable stiffness unit 2, and a base 3. The base 3 includes a first rod 31 and a second rod 32 and a third rod 35 connected to opposite ends of the first rod 31. Two slide rails 34 are provided on the side of the first rod 31 facing the second rod 32. The locking unit 1 includes a composite bridge compliant component 11, which is slidably connected between the two slide rails 34. A first piezoelectric stack 5 is provided inside the composite bridge compliant component 11 to restrict the sliding of the composite bridge compliant component 11 within the slide rails 34. The variable stiffness unit 2 includes a leaf spring 21 and a drive assembly. The drive assembly includes a first drive mechanism 22 and a second drive mechanism 25. The opposing sides of the second rod 32 and the third rod 35 are respectively rotatably connected to the first drive mechanism 22. The first drive mechanism 22 and the second drive mechanism 25 are connected. One end of the composite bridge compliant component 11 is connected to the leaf spring 21. The end of the leaf spring 21 facing away from the composite bridge compliant component 11 is clamped between the first drive mechanism 22 and the second drive mechanism 25. The opposing sides of the second rod 32 and the third rod 35 are provided with limiting rods 33. The limiting rods 33 are located between the first rod 31 and the drive assembly. The end of the leaf spring 21 facing away from the composite bridge compliant component 11 is clamped between the two limiting rods 33. One limiting rod 33, the third rod 35, the leaf spring 21 and the first drive mechanism 22 enclose a first cavity. The other limiting rod 33, the second rod 32, the leaf spring 21 and the second drive mechanism 25 enclose a second cavity. A second piezoelectric stack 6 is provided in the first cavity and a third piezoelectric stack 7 is provided in the second cavity.

[0014] Specifically, the stick-slip driven variable stiffness compliant mechanism with lockable movement is planar in shape and includes three parts: left, middle and right. The left and right parts are the variable stiffness units 2. The first drive mechanism 22 and the second drive mechanism 25 are placed symmetrically. The base 3 is integrated with the first drive mechanism 22 and the second drive mechanism 25. The base 3 is provided with bolts 8, which can be used to fix the mechanism to the end of the robotic arm or the worktable. The middle part is the locking unit 1.

[0015] The composite bridge-type compliant component 11 includes a first telescopic block 111, a first fixing block 112, a second telescopic block 113, and a second fixing block 114. The first fixing block 112 and the second fixing block 114 are arranged opposite to each other. The first telescopic block 111 and the second telescopic block 113 are arranged between the first fixing block 112 and the second fixing block 114. The opposite ends of the first telescopic block 111 are connected to the first fixing block 112 and the second fixing block 114 respectively by two first flexible inclined beams 115. The opposite ends of the second telescopic block 113 are connected to the first fixing block 112 and the second fixing block 114 respectively by two second flexible inclined beams 116. A cavity is formed by a fixed block 114, a first telescopic block 111, a second telescopic block 113, two first flexible inclined beams 115, and two second flexible inclined beams 116. A first piezoelectric stack 5 is disposed in the cavity. The first piezoelectric stack 5 can extend along the axial direction after an input voltage is applied, and can quickly return to its original shape when the input voltage is reduced. A first wedge 51 is disposed between the first fixed block 112 and the first piezoelectric stack 5. The first wedge 51 is used to pre-tighten the first piezoelectric stack 5. A second through hole is provided on the first flexible inclined beam 115 and the second flexible inclined beam 116 to make the rotation of the first flexible inclined beam 115 and the second flexible inclined beam 116 smoother.

[0016] The locking unit 1 further includes a fixing structure 12, which includes a first plate 122 and a second plate 123. The composite bridge flexible component 11 is connected to the first plate 122 and the second plate 123 at one end facing the leaf spring 21. A first clamping space is formed between the first plate 122 and the second plate 123. One end of the leaf spring 21 is placed in the first clamping space. A first through hole 124 perpendicular to the leaf spring 21 is opened on both the first plate 122 and the second plate 123. An opening adapted to the first through hole 124 is opened on the leaf spring 21. A fixing pin 121 is provided in the first through hole 124 to fix the leaf spring 21 to the first plate 122 and the second plate 123.

[0017] The first driving mechanism 22 includes a first hinge 23 and a first driving foot 24. The first driving foot 24 is connected to the second rod 32 via the first hinge 23. The end of the first driving foot 24 facing away from the first hinge 23 abuts against the leaf spring 21. The two opposite ends of the second piezoelectric stack 6 abut against one of its limiting rods 33 and the first driving foot 24, respectively. A second wedge 61 is provided between the second piezoelectric stack 6 and its limiting rod 33. The second wedge 61 is used to pre-tighten the second piezoelectric stack 6. The first driving foot 24 includes an extension rod 241 and a bending rod 242. One end of the extension rod 241 is connected to the first hinge 23, and the end of the extension rod 241 facing away from the first hinge 23 is connected to the bending rod 242. The bending rod 242 faces away from the extension rod 241. One end of the second piezoelectric stack 6 extends from the extension rod 241 toward the limiting rod 242. The extension rod 241 is used to amplify the displacement of the second piezoelectric stack 6. The bending rod 242 makes the movement of the leaf spring smoother. The second drive mechanism 25 includes a second hinge 27 and a second drive foot 26. The second drive foot 26 is connected to the second rod 32 through the second hinge 27. The end of the second drive foot 26 facing away from the second hinge 27 abuts against the leaf spring 21. The two opposite ends of the second piezoelectric stack 6 abut against one of its limiting rods 33 and the first drive foot 24, respectively. A second wedge 71 is provided between the third piezoelectric stack 7 and one of its limiting rods 33. The second wedge 71 is used to pre-tighten the second piezoelectric stack 7. The structure of the second drive foot 26 is the same as that of the first drive foot 24.

[0018] Specifically, the first hinge 23 serves as a pivot point. When the second piezoelectric stack 6 extends, the first driving foot 24 rotates around the first hinge 23. Therefore, the output displacement of the first driving foot 24 is the amplified displacement of the second piezoelectric stack 6 after passing through the bending member 242. Since the first driving foot 24 is fixed while the leaf spring 21 is movable, when the input voltage of the second piezoelectric stack 6 slowly increases, the second piezoelectric stack 6 slowly extends, and the first driving foot 24 provides a driving force to the leaf spring 21, causing the leaf spring 21 to move. When the input voltage of the second piezoelectric stack 6 rapidly decreases, the second piezoelectric stack 6 rapidly contracts. The first drive foot 24 recovers from slight deformation to its original state. Due to inertia, the leaf spring 21 will continue to slide a short distance along the previous direction of movement. In each cycle, the first drive mechanism 22 repeats the above steps, inputting a periodic sawtooth wave voltage to the second piezoelectric stack 6. Through the accumulation of small displacements step by step, the leaf spring 21 can achieve a large working stroke. The principle of the second drive mechanism 25 is the same as that of the first drive mechanism 22. Moreover, the direction of movement of the leaf spring 21 can be changed by simply changing the symmetry of the sawtooth wave. Therefore, this stick-slip drive variable stiffness compliant mechanism with lockable movement can be freely changed to the required stiffness.

[0019] When the stick-slip driven variable stiffness compliant mechanism with lockable movement reaches the required stiffness, the composite bridge compliant component 11 is given an input displacement through the first piezoelectric stack 5. The distance between the first fixed block 112 and the second fixed block 114 increases, and the first flexible inclined beam 115 and the second flexible inclined beam 116 are straightened. Correspondingly, the distance between the first telescopic block 111 and the second telescopic block 113 also increases. The first telescopic block 111 and the second telescopic block 113 squeeze the slide rail 34, thereby increasing the friction force between the first telescopic block 111, the second telescopic block 113 and the slide rail 34, thus realizing the displacement locking function of the composite bridge compliant mechanism 4.

[0020] It should be noted that when an element is said to be "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is said to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "middle," "right," "first," "second," "third," and similar expressions used in this document are for illustrative purposes only.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "and," "and," and "or" as used herein include any and all combinations of one or more of the associated listed items.

[0022] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims

1. A stick-slip driven variable stiffness compliant mechanism with lockable movement, characterized in that, include: The system comprises a base, a locking unit, and a variable stiffness unit. The base includes a first rod and second and third rods connected to opposite ends of the first rod. Two slide rails are provided on the side of the first rod facing the second rod. The locking unit includes a composite bridge-type compliant assembly slidably connected between the two slide rails. A first piezoelectric stack is disposed inside the composite bridge-type compliant assembly to restrict the sliding of the composite bridge-type compliant assembly within the slide rails. The variable stiffness unit includes a leaf spring and a drive assembly. The drive assembly includes a first drive mechanism and a second drive mechanism. The opposing sides of the second and third rods are respectively rotatably connected to the first drive mechanism and the second drive mechanism. One end of the composite bridge compliant component is connected to the leaf spring. The end of the leaf spring facing away from the composite bridge compliant component is clamped between the first driving mechanism and the second driving mechanism. A limiting rod is provided on the facing side of the second rod and the third rod. The limiting rod is located between the first rod and the component. The end of the leaf spring facing away from the composite bridge compliant component is clamped between the two limiting rods. One limiting rod, the third rod, the leaf spring and the first driving mechanism form a first cavity. The other limiting rod, the second rod, the leaf spring and the second driving mechanism form a second cavity. A second piezoelectric stack is provided in the first cavity and a third piezoelectric stack is provided in the second cavity.

2. The stick-slip driven variable stiffness compliant mechanism with lockable movement according to claim 1, characterized in that, The composite bridge-type compliant component includes a first fixed block, a second fixed block, a first telescopic block, and a second telescopic block. The first fixed block and the second fixed block are arranged opposite to each other. The first telescopic block and the second telescopic block are arranged between the first fixed block and the second fixed block. The opposite ends of the first telescopic block are connected to the first fixed block and the second fixed block respectively by two first flexible inclined beams. The opposite ends of the second telescopic block are connected to the first fixed block and the second fixed block respectively by two second flexible inclined beams. The first fixed block, the second fixed block, the first telescopic block, the second telescopic block, the two first flexible inclined beams, and the two second flexible inclined beams enclose a receiving cavity. The first piezoelectric stack is arranged inside the receiving cavity.

3. The stick-slip driven variable stiffness compliant mechanism with lockable movement according to claim 1, characterized in that, The locking unit further includes a fixing structure, which includes a first plate and a second plate. The composite bridge-type compliant component is connected to the first plate and the second plate at one end facing the leaf spring. A first clamping space is formed between the first plate and the second plate. One end of the leaf spring is placed in the first clamping space. A first through hole perpendicular to the leaf spring is opened on both the first plate and the second plate. An opening adapted to the first through hole is opened on the leaf spring. A fixing pin is provided in the first through hole to fix the leaf spring to the first plate and the second plate.

4. The stick-slip driven variable stiffness compliant mechanism with lockable movement according to claim 2, characterized in that, Both the first flexible inclined beam and the second flexible inclined beam have a through second hole.

5. The stick-slip driven variable stiffness compliant mechanism with lockable movement according to claim 1, characterized in that, The first driving mechanism includes a first hinge and a first driving foot. The first driving foot is connected to the third rod through the first hinge. One end of the first driving foot facing away from the first hinge abuts against the leaf spring. The two opposite ends of the second piezoelectric stack abut against the limiting rod and the first driving foot, respectively.

6. The stick-slip driven variable stiffness compliant mechanism with lockable movement according to claim 5, characterized in that, The first driving foot includes an extension rod and a bending rod. One end of the extension rod is connected to the first hinge, and the end of the extension rod facing away from the first hinge is connected to the bending rod. The end of the bending rod facing away from the extension rod extends from the extension rod toward the limiting rod.

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