Adjustable stiffness micro-gripping device with enveloping gripping feature and gripping method

Abstract

This invention discloses an adjustable stiffness micro-clamping device with envelope clamping characteristics. The device includes a base and a flexible clamping arm mounted on the base. Piezoelectric ceramic actuators are mounted on the bottom and side walls of the base. A lever-type hinge is connected to one side of the base, with its two ends connected to the output end of the piezoelectric ceramic actuator at the bottom and one side of the flexible clamping arm, respectively. The output end of the piezoelectric ceramic actuator on the side is connected to the other side of the flexible clamping arm via a variable stiffness adjustment mechanism. A first clamping finger is connected to the top of the flexible clamping arm via an output connecting plate. A second clamping finger is connected to the top of the base side wall at a position corresponding to the first clamping finger. The postures of the first and second clamping fingers are adjustable. The device has a compact structure, rapid response, and can correct the clamping posture in real time, eliminating clamping deviations and stress concentrations, thus improving clamping accuracy and adaptability. This invention also discloses an adjustable stiffness micro-clamping method with envelope clamping characteristics, which has a wide range of applications.

Description

Technical Field

[0001] This invention belongs to the technical field of micro-operation, micro-assembly and precision gripping equipment, specifically relating to an adjustable stiffness micro-gripping device with envelope clamping characteristics, and also to an adjustable stiffness micro-gripping method with envelope clamping characteristics. Background Technology

[0002] In precision manufacturing and micro-operation fields such as micro-assembly, micro-operation, and precision gripping, the micro gripper, as a core execution component, directly determines the accuracy, stability, and reliability of the operation process and plays a crucial role in the gripping quality of tiny parts.

[0003] With the rapid development of microelectromechanical technology, the size of micro parts continues to shrink and their structures become increasingly complex. The industry has put forward higher application requirements for the self-adaptive ability, stiffness adjustability, clamping accuracy and non-destructive clamping performance of micro grippers.

[0004] Traditional micro grippers suffer from numerous performance defects, making it difficult to meet the practical demands of micro-assembly and precision grasping. Firstly, their clamping stiffness is often fixed, resulting in poor adaptability. They cannot dynamically adjust to the size, material, or fragility of the clamped parts. Excessive stiffness can easily damage fragile components such as biological cells and thin microchips, while insufficient stiffness leads to slippage and detachment due to inadequate clamping stability, failing to meet the precision standards required for grasping. Secondly, they lack adaptability and operational flexibility. Fixed clamping angles and travel distances cannot be adjusted based on the shape and size variations of the clamped parts. For irregularly shaped or dimensionally fluctuating micro-parts, achieving a close fit is difficult, leading to uneven clamping force distribution and further affecting clamping accuracy and stability. Thirdly, they cannot balance clamping accuracy and operational stability. In practical use, uneven clamping force distribution and large synchronization errors on both sides are common problems. Furthermore, the lack of a fixed positioning reference results in lower clamping positioning accuracy, significantly limiting their applicability in high-precision micro-operations and the clamping of fragile micro-objects. Summary of the Invention

[0005] The purpose of this invention is to provide an adjustable stiffness micro-clamping device with envelope clamping characteristics, which solves the problems of low stiffness adaptability and large error caused by uneven clamping force distribution in the prior art.

[0006] Another object of the present invention is to provide an adjustable stiffness micro-clamping method with envelope clamping characteristics.

[0007] The technical solution adopted in this invention is an adjustable stiffness micro-clamping device with envelope clamping characteristics, including a base and a flexible clamping arm mounted on the base. Piezoelectric ceramic actuators are respectively mounted on the bottom and side walls of the base. A lever-type hinge is connected to one side of the base. The two ends of the lever-type hinge are respectively connected to the output end of the piezoelectric ceramic actuator at the bottom and one side of the flexible clamping arm. The output end of the piezoelectric ceramic actuator on the side is connected to the other side of the flexible clamping arm through a variable stiffness adjustment mechanism. The top of the flexible clamping arm is connected to a first clamping finger via an output connection plate, and the top of the base sidewall is connected to a second clamping finger at a position corresponding to the first clamping finger. The postures of the first and second clamping fingers are adjustable.

[0008] The invention is further characterized in that, The base is rigidly formed by the base bottom crossbeam, the base rear plate, and the rear limiting plate. The rear limiting plate and the base bottom crossbeam form a T-shaped structure. The base rear plate extends upward from the top of the rear limiting plate and is fixed in the preset installation position by fixing screws. The bottom of the base's bottom crossbeam has a bottom mounting groove, and the bottom piezoelectric ceramic actuator is embedded in the bottom mounting groove. The lever-type hinge is connected to the end of the base's bottom crossbeam through a flexible hinge. The rear plate of the base has symmetrically opened side piezoelectric ceramic mounting slots near the center, and each side piezoelectric ceramic driver is installed in the side piezoelectric ceramic mounting slot.

[0009] A first preload adjustment screw is inserted through the rear limit plate at the position corresponding to the bottom piezoelectric ceramic actuator; a second preload adjustment screw is inserted through the rear plate of the base at the position corresponding to the side piezoelectric ceramic actuator; elastic washers are provided between the tip of the first preload adjustment screw and the bottom piezoelectric ceramic actuator, and between the second preload adjustment screw and the side piezoelectric ceramic actuator.

[0010] The flexible clamping arm includes a front clamping arm and a rear clamping arm that are parallel to each other. The upper and lower ends of the front clamping arm are connected to the output connection plate and the base respectively through flexible hinges. The upper and lower ends of the rear clamping arm are connected to the output connection plate and the base respectively through flexible hinges.

[0011] The front clamping arm is a rigid beam with a hollow slit in the upper middle section to form a hollow slit rigid beam. The top of the hollow slit rigid beam is connected to the output connecting plate through a flexible hinge, and the bottom of the front clamping arm is connected to the base through a flexible hinge. The position of the front clamping arm near the bottom is connected to the end of the lever-type hinge through a flexible hinge. The rear clamping arm is formed by symmetrical arrangement of the left and right flexible plates to form an X-shaped non-cross structure. The upper and lower ends of the left and right flexible plates are respectively fixed with upper rigid connecting beams and lower rigid connecting beams. The upper rigid connecting beam is connected to the output connecting plate through a flexible hinge, and the lower rigid connecting beam is connected to the base through a flexible hinge. The middle stress-bearing sections of the left and right flexible plates are respectively connected to the variable stiffness adjustment mechanism.

[0012] The variable stiffness adjustment mechanism includes two L-shaped lever hinges. One end of each L-shaped lever hinge is connected to the output end of the corresponding side piezoelectric ceramic actuator, and the other end is rigidly connected to the middle force-bearing section of the left and right side flexible plates of the rear clamping arm through a double-layer elastic sheet.

[0013] The first clamping finger and the second clamping finger, which extends from directly above the rear plate of the base, together form the clamping jaws of the micro gripper, and the output connecting plate is parallel to the bottom crossbeam of the base.

[0014] A single-layer piezoelectric self-sensing actuator is rigidly attached to the side of the first clamping finger away from the second clamping finger. The single-layer piezoelectric self-sensing actuator uses a single-layer piezoelectric ceramic sheet, which causes the first clamping finger to bend slightly through deformation, thereby achieving a slight correction of the clamping posture.

[0015] The second clamping finger includes a double-layer substrate arranged in parallel. The double-layer substrate is separated into upper and lower sections by a hinge connecting the double-layer substrate. The upper and lower sections are respectively embedded with piezoelectric fiber actuators. The piezoelectric fiber actuators are arranged along the length of the clamp. The second clamping finger is connected to the top of the side wall of the base through an L-shaped support rod. A piezoelectric fiber actuator is also embedded in the interlayer section where the L-shaped support rod is connected to the second clamping finger. This is used to control the degree of bending of the L-shaped support rod, thereby adjusting the vertical position of the second clamping finger and causing the second clamping finger to bend and deform, so as to achieve adhesion with the micro-object.

[0016] Another technical solution adopted in this invention is an adjustable stiffness micro-clamping method with envelope clamping characteristics, the steps of which are as follows: The piezoelectric ceramic actuator at the bottom of the base undergoes axial micro-elongation under excitation voltage. After being amplified by the lever-type hinge, it pushes the flexible clamping arm to move in the same direction from its upper end, driving the output connecting plate to translate and causing the first clamping finger to move and open. The piezoelectric ceramic actuator on the side drives the variable stiffness adjustment mechanism to apply force to the flexible clamping arm, changing the degree of bending of the flexible plates on the left and right sides of the flexible clamping arm. The first and second clamping fingers adjust their posture so that the clamping end faces of the two clamping fingers fit against the surface of the micro-object.

[0017] The beneficial effects of this invention are: The present invention relates to an adjustable stiffness micro-gripping device with envelope clamping features. It employs a variable stiffness adjustment mechanism, clamp envelope, and independent drive for attitude correction, allowing for flexible control without functional interference. A bottom piezoelectric drive enables high-precision opening and closing, while double-sided piezoelectric drive combined with an X-shaped non-crossing flexible plate achieves continuously adjustable clamping stiffness, balancing non-destructive clamping with clamping stability. A single-layer piezoelectric self-sensing actuator on the left and a piezoelectric fiber actuator on the right work together to complete attitude correction and object envelope, enabling real-time correction of clamping posture, eliminating clamping deviations and stress concentrations, and improving clamping accuracy and adaptability to irregularly shaped and dimensionally variable micro-objects. This device solves the problems of fixed stiffness and easy damage to objects in traditional micro-grippers, featuring a compact structure, rapid response, and significantly improved clamping stability and non-destructive performance. The adjustable stiffness micro-clamping method with envelope clamping features of the present invention is suitable for complex operations such as precise grasping, handling, assembly and precision operation of objects at the micrometer scale. In particular, it can be adapted to different types of objects with different stiffness characteristics, such as fragile biological samples, precision electronic devices, micro-optical elements and micro-mechanical structures, to achieve non-destructive and high-precision micro-manipulation. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural schematic diagram of the adjustable stiffness micro-clamping device with envelope clamping features of the present invention. Figure 2 This is a three-dimensional structural cross-sectional view of the adjustable stiffness micro-clamping device with envelope clamping features of the present invention. Figure 3 This is a schematic diagram of the bottom piezoelectric driven flexible clamping mechanism of the present invention; Figure 4 This is a schematic diagram of the piezoelectric linkage variable stiffness adjustment mechanism of the present invention; Figure 5 This is a schematic diagram of the structure of the clamp with envelope clamping feature of the present invention; Figure 6 This is a flowchart of the adjustable stiffness micro-clamping method with envelope clamping features of the present invention.

[0019] In the diagram, 1. Lever-type hinge; 2. First preload adjusting screw; 21. Second preload adjusting screw; 3. Bottom piezoelectric ceramic actuator; 31. Side piezoelectric ceramic actuator; 4. Elastic gasket; 5. Flexible clamping arm; 51. Front clamping arm; 511. Hollow slit rigid beam; 52. Rear clamping arm; 522. Left flexible plate; 523. Right flexible plate; 524. Upper rigid connecting beam; 525. Lower rigid connecting beam; 53. First clamping finger; 54. Second clamping finger; 541. Substrate connecting hinge; 542. Front substrate; 543. Rear substrate; 55. Output connection board; 6. Variable stiffness adjustment mechanism: 61. Left L-shaped lever hinge; 62. Right L-shaped lever hinge; 63. Left double-layer elastic plate; 64. Right double-layer elastic plate; 7. Rear plate of base; 71. Rear limiting plate; 72. Bottom crossbeam of base; 8. Single-layer piezoelectric self-sensing actuator; 9. Piezoelectric fiber actuator; 10. L-shaped support rod; 11. Fixing screw. Detailed Implementation

[0020] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] Example 1 This invention relates to an adjustable stiffness micro-clamping device with envelope clamping characteristics, the structure of which is as follows: Figure 1 As shown, it includes a base and a flexible clamping arm 5 mounted on the base. Piezoelectric ceramic actuators are mounted on the bottom and side walls of the base, respectively. A lever-type hinge 1 is connected to one side of the base. The two ends of the lever-type hinge 1 are connected to the output end of the piezoelectric ceramic actuator at the bottom and one side of the flexible clamping arm 5, respectively. The output end of the piezoelectric ceramic actuator on the side is connected to the other side of the flexible clamping arm 5 through a variable stiffness adjustment mechanism 6. The top of the flexible gripping arm 5 is connected to a first clamping finger 53 via an output connecting plate 55. The first clamping finger 53 is integrally formed at the end of the output connecting plate 55 to form the working jaw of the micro gripper, which is used to directly contact and clamp small objects. The top of the base side wall is connected to a second clamping finger 54 at a position corresponding to the first clamping finger 53. The postures of the first clamping finger 53 and the second clamping finger 54 are adjustable.

[0022] The first clamping finger 53 and the second clamping finger 54 have an enveloping feature, which can control the tilt angle of the first clamping finger 53 and the bending direction and degree of the second clamping finger 54 respectively, so that the clamping end faces of the two clamps fit into the surface of the micro-object, adapting to micro-objects of different sizes and irregular shapes, and improving clamping efficiency.

[0023] Example 2 Based on Example 1, such as Figure 1 and Figure 2 As shown, the base includes a base rear plate 7, a rear limiting plate 71, and a base bottom crossbeam 72.

[0024] The base rear plate 7, rear limiting plate 71, and base bottom crossbeam 72 are integrally rigidly molded, serving as the basic support carrier for the entire micro gripper. The rear limiting plate 71 and base bottom crossbeam 72 form a T-shaped structure, with the base rear plate 7 extending upwards from the top of the rear limiting plate 71. The base rear plate 7 is connected and fixed by fixing screws 11. Four fixing screws 11 are provided, which are screwed into the corresponding screw holes of the base rear plate 7 and connected and fixed in the preset installation position.

[0025] The middle section of the lever-type hinge 1 is connected to the end of the bottom crossbeam 72 of the base via a flexible hinge; the bottom of the bottom crossbeam 72 of the base is provided with a bottom piezoelectric ceramic mounting groove, which is used to install the bottom piezoelectric ceramic actuator 3; the rear plate 7 of the base is symmetrically provided with side piezoelectric ceramic mounting grooves near the center, and each side piezoelectric ceramic actuator 31 is installed in the side piezoelectric ceramic mounting groove.

[0026] Both the bottom piezoelectric ceramic actuator 3 and the side piezoelectric ceramic actuator 31 are piezoelectric stacked ceramic structures. They can independently receive excitation voltage signals and output micro-displacement, which is transmitted to the controller to enable the flexible clamping arm 5 to drive the first clamping finger 53 to move and to achieve symmetrical force application on the X-shaped non-crossing flexible plate, thereby ensuring the uniformity of the clamping arm stiffness adjustment. A first preload adjustment screw 2 is inserted through the rear limiting plate 71 at a position corresponding to the bottom piezoelectric ceramic actuator 3, and a second preload adjustment screw 21 is inserted through the rear plate 7 of the base at a position corresponding to the side piezoelectric ceramic actuator 31. An elastic washer 4 is provided between the tip of the first preload adjustment screw 2 and the bottom piezoelectric ceramic actuator 3. An elastic washer 4 is provided between the second preload adjustment screw 21 and the side piezoelectric ceramic actuator 31.

[0027] By adjusting the tightness of the first preload adjusting screw 2, the bottom piezoelectric ceramic actuator 3 can be actively preloaded, ensuring the installation coaxiality and operational stability of the bottom piezoelectric ceramic actuator 3.

[0028] Two preload adjusting screws 21 are screwed into the preload screw holes at the bottom of the base rear plate 7, pushing the elastic washer 4 located between the end of the side piezoelectric ceramic actuator 31 and the base rear plate 7. This is used to precisely adjust the preload of the side piezoelectric ceramic actuator 31, eliminate assembly gaps to ensure the continuity of power transmission and the consistency of response, and at the same time ensure the uniform transmission of driving force and improve the displacement output accuracy. The elastic washer 4 is a thin plate structure.

[0029] The integrated rigid base is a one-piece metal forming structure. The base also has an L-shaped lever hinge bearing position and a lever hinge 1 connection position. All mounting slots, mounting positions and bearing positions are integrally processed and formed, providing a foundation for fixing and assembling each functional unit, and ensuring the stability and coaxiality of the overall structure of the micro gripper.

[0030] Example 3 Based on Example 2, such as Figure 2 and Figure 3 As shown, the flexible clamping arm 5 includes a front clamping arm 51 and a rear clamping arm 52, which are arranged in parallel front and rear on the bottom crossbeam 72 of the base directly in front of the rear plate 7 of the base. The lower ends of the front clamping arm 51 and the rear clamping arm 52 are connected to the bottom crossbeam 72 of the base directly below them by flexible hinges. The output connecting plate 55 is connected to the upper ends of the front clamping arm 51 and the rear clamping arm 52 by flexible hinges, and is arranged directly above them and parallel to the bottom crossbeam 72 of the base.

[0031] The lever-type hinge 1 is arranged in front of the front clamping arm 51; the upper end of the lever-type hinge 1 is connected to the front clamping arm 51 near the bottom via a flexible hinge, the lower end of the lever-type hinge 1 is connected to the output end of the bottom piezoelectric ceramic actuator 3 via a flexible hinge, and the middle fulcrum is connected to the bottom crossbeam 72 of the base via a flexible hinge.

[0032] The front clamping arm 51 is a rigid beam. The upper section of the rigid beam is cut into a hollow cut rigid beam 511. The top of the hollow cut rigid beam 511 is connected to the output connecting plate 55 through a flexible hinge.

[0033] The rear clamping arm 52 includes an upper rigid connecting beam 524, a lower rigid connecting beam 525, a left flexible plate 522, and a right flexible plate 523. The upper ends of the left flexible plate 522 and the right flexible plate 523 are respectively fixed to the bottom ends of the upper rigid connecting beam 524, and the lower ends of the left flexible plate 522 and the right flexible plate 523 are respectively fixed to the top ends of the lower rigid connecting beam 525. The upper rigid connecting beam 524 is connected to the output connecting plate 55 via a flexible hinge, and the lower rigid connecting beam 525 is connected to the base via a flexible hinge.

[0034] The flexible plate 522 on the left and the flexible plate 523 on the right are arranged symmetrically to form an X-shaped non-intersecting structure.

[0035] The first clamping finger 53 and the second clamping finger 54, which extends from directly above the rear plate 7 of the base, together form the clamping jaws of the micro gripper. The bottom piezoelectric ceramic actuator 3 drives the lever hinge 1 to drive the front clamping arm 51 and the rear clamping arm 52 to move in the same direction to achieve clamping. By amplifying the micro-displacement of the bottom piezoelectric ceramic through the lever hinge 1, the first clamping finger 53 above the rear end of the output connecting plate 55 is driven to move, thereby achieving precise opening and closing of the jaws and completing the grasping and release of micro-objects.

[0036] Example 4 Based on Example 3, such as Figure 4As shown, the variable stiffness adjustment mechanism 6 is arranged in front of the base rear plate 7, including a left L-shaped lever hinge 61, a right L-shaped lever hinge 62, a left double-layer elastic plate 63 and a right double-layer elastic plate 64.

[0037] The side piezoelectric ceramic actuator 31 works in conjunction with the rear clamping arm 52. The force input ends of the left L-shaped lever hinge 61 and the right L-shaped lever hinge 62 are pre-tightly connected to the output ends of their respective side piezoelectric ceramic actuators 31, so as to apply forces to the X-shaped left flexible plate 522 and X-shaped right flexible plate 523 of the rear clamping arm 52, respectively. The two ends of the left double-layer elastic sheet 63 are respectively fixed between the force output end of the left L-shaped lever hinge 61 and the middle force-bearing area of ​​the X-shaped left flexible plate 522 of the rear clamping arm 52. The two ends of the right double-layer elastic sheet 64 are respectively fixed between the force output end of the right L-shaped lever hinge 62 and the middle force-bearing area of ​​the X-shaped right flexible plate 523 of the rear clamping arm 52. The change in the bending curvature of the X-shaped non-crossing flexible plate directly determines the overall equivalent bending stiffness of the clamping arm.

[0038] Example 5 Based on Example 4, such as Figure 1 and Figure 5 As shown, a single-layer piezoelectric self-sensing actuator 8 is rigidly attached to the side of the first clamping finger 53 away from the second clamping finger 54. The single-layer piezoelectric self-sensing actuator 8 is connected to the controller. The single-layer piezoelectric self-sensing actuator 8 uses a single-layer piezoelectric ceramic sheet. Through deformation, it causes the first clamping finger 53 to bend slightly, thereby achieving a slight correction of the clamping posture.

[0039] The second clamping finger 54 is connected to the top of the base rear plate 7 via an L-shaped support rod 10. The second clamping finger 54 includes a front base plate 542, a rear base plate 543, and a base plate connecting hinge 541. The front base plate 542 and the rear base plate 543 are arranged in parallel and are separated into upper and lower sections by the connecting hinge 541. The upper and lower sections are respectively embedded with piezoelectric fiber actuators 9. The piezoelectric fiber actuators 9 are arranged along the length of the clamp and are connected to a controller to control the second clamping finger 54 to undergo micro-bending deformation.

[0040] A piezoelectric fiber actuator 9 is also embedded in a section of the interlayer connecting the L-shaped support rod 10 and the second clamping finger 54. The piezoelectric fiber actuator 9 is connected to a controller to control the degree of bending of the L-shaped support rod 10 and the corresponding section of the double-layer substrate, thereby controlling the vertical position of the second clamping finger 54 and causing the second clamping finger 54 to bend and deform, thus fitting with the micro-object and realizing the envelopment of micro-objects of different sizes and irregular shapes.

[0041] The first clamping finger 53 and the second clamping finger 54 have an enveloping feature, which controls the tilt angle of the first clamping finger and the bending direction and degree of the second clamping finger, respectively, so that the clamping end faces of the two clamps fit into the surface of the micro-object, thereby improving adaptability and clamping efficiency.

[0042] The adjustable stiffness micro-gripping device of the present invention, featuring envelope clamping characteristics, firstly utilizes a bottom piezoelectric ceramic actuator in conjunction with a lever-type hinge 1 to drive the translation of the flexible clamping arm 5, achieving precise opening and closing of the clamps. Secondly, through double-sided piezoelectric ceramic-driven L-shaped lever hinges acting on an X-shaped non-crossing flexible plate, the bending degree is adjusted to achieve continuously adjustable clamping stiffness, enabling the switching between high and low stiffness clamping modes while balancing clamping stability and non-destructive operation. Furthermore, relying on the coordinated drive of a single-layer piezoelectric self-sensing actuator on the left and a piezoelectric fiber actuator on the right, the clamping fingers are slightly bent, completing adaptive correction and envelope of the clamping posture, adapting to the grasping needs of micro-objects of different sizes, and improving clamping efficiency and accuracy. The synergistic effect of these mechanisms significantly enhances the adaptability and operational reliability of the micro-gripper, making it more suitable for complex scenarios such as micro-assembly and precision grasping.

[0043] Example 6 The adjustable stiffness micro-clamping method with envelope clamping feature of the present invention adopts the adjustable stiffness micro-clamping device with envelope clamping feature of Example 5, and the process is as follows: Figure 6 As shown, the steps are as follows: The piezoelectric ceramic actuator 3 at the bottom of the base undergoes a slight axial elongation under excitation voltage. This elongation is amplified by the lever-type hinge 1, pushing the front clamping arm 51 from its upper end and causing the rear clamping arm 52 to move in the same direction. Ultimately, this drives the output connecting plate 55 at the upper end of the front and rear clamping arms 51 to translate, causing the first clamping finger 53 to move and open / close. The two side piezoelectric ceramic actuators 31 respectively drive the left L-shaped lever hinge 61 and the right L-shaped lever hinge 62 to apply force to the left and right flexible plates 522 and 523 of the X-shaped non-crossing flexible plate, thereby changing their degree of bending and adjusting the stiffness of the clamping arms. The first clamping finger 53 and the second clamping finger 54 adjust their posture so that the clamping end faces of the two clamping fingers fit against the surface of the micro-object.

[0044] The attitude adjustment of the first clamping finger 53 and the second clamping finger 54 is specifically as follows: a single-layer piezoelectric self-sensing actuator 8 is attached to the front surface of the first clamping finger 53 by conductive adhesive. The controller controls the single-layer piezoelectric self-sensing actuator 8 to generate controllable deformation to drive the first clamping finger 53 to move, thereby realizing the correction and compensation of the attitude deviation of the first clamping finger 53. The controller applies a controllable electrical signal to the piezoelectric fiber actuator 9 to drive it to generate corresponding deformation. The piezoelectric fiber actuator 9 then drives the upper and lower segments of the substrate of the second clamping finger 54 to bend, while adjusting the bending direction and degree of the upper and lower segments of the substrate, and realizing precise control of the vertical displacement of the second clamping finger 54.

[0045] Based on the above technical solution, the advantages of the present invention compared with the prior art are as follows: This invention employs a variable stiffness adjustment mechanism, clamp envelope, and independent drive for attitude correction, offering flexible control without functional interference. It is adaptable to micro-manipulation scenarios such as micro-assembly and precision gripping. By combining side piezoelectric drive with an X-shaped non-crossing flexible plate, it achieves precise adjustment of clamping stiffness, perfectly balancing non-destructive clamping and clamping stability. Relying on the coordinated action of the left and right piezoelectric drive components, it can correct the clamping posture in real time, eliminating clamping deviation and stress concentration, improving clamping accuracy and adaptability to irregularly shaped and dimensionally variable micro-objects. This design is compact, highly integrated, and easy to integrate with micro-manipulation equipment, facilitating assembly and maintenance, and significantly improving the operational reliability and engineering practicality of the micro-gripper. The adjustable stiffness micro-clamping method with envelope clamping features of the present invention is suitable for complex operations such as precise grasping, handling, assembly and precision operation of objects at the micrometer scale. In particular, it can be adapted to different types of objects with different stiffness characteristics, such as fragile biological samples, precision electronic devices, micro-optical elements and micro-mechanical structures, to achieve non-destructive and high-precision micro-manipulation.

[0046] The above description is only a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or changes based on the technical solution and concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. An adjustable stiffness micro-clamping device with envelope clamping characteristics, characterized in that, Includes a base and a flexible clamping arm (5) mounted on the base. Piezoelectric ceramic actuators are installed on the bottom and side walls of the base respectively. A lever-type hinge (1) is connected to one side of the base. The two ends of the lever-type hinge (1) are connected to the output end of the piezoelectric ceramic actuator at the bottom and one side of the flexible clamping arm (5) respectively. The output end of the piezoelectric ceramic actuator on the side is connected to the other side of the flexible clamping arm (5) through a variable stiffness adjustment mechanism (6). The top of the flexible clamping arm (5) is connected to a first clamping finger (53) via an output connecting plate (55), and the top of the base sidewall is connected to a second clamping finger (54) at a position corresponding to the first clamping finger (53). The postures of the first clamping finger (53) and the second clamping finger (54) are adjustable.

2. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 1, characterized in that, The base is integrally rigidly formed by the base bottom crossbeam (72), the base rear plate (7), and the rear limiting plate (71). The rear limiting plate (71) and the base bottom crossbeam (72) form a T-shaped structure. The base rear plate (7) extends upward from the top of the rear limiting plate (71). The base rear plate (7) is connected and fixed in the preset installation position by fixing screws (11). The bottom piezoelectric ceramic actuator (3) is embedded in the bottom of the base bottom crossbeam (72), and the lever-type hinge (1) is connected to the end of the base bottom crossbeam (72) through a flexible hinge; The base rear plate (7) is symmetrically equipped with side piezoelectric ceramic actuators (31) near the center.

3. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 2, characterized in that, The rear limiting plate (71) is provided with a first pre-tightening adjustment screw (2) at the corresponding position of the bottom piezoelectric ceramic actuator (3); the base rear plate (7) is provided with a second pre-tightening adjustment screw (21) at the corresponding position of the side piezoelectric ceramic actuator (31); elastic washers (4) are provided between the tip of the first pre-tightening adjustment screw (2) and the bottom piezoelectric ceramic actuator (3), and between the second pre-tightening adjustment screw (21) and the side piezoelectric ceramic actuator (31).

4. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 2, characterized in that, The flexible clamping arm (5) includes a front clamping arm (51) and a rear clamping arm (52) that are parallel to each other. The upper and lower ends of the front clamping arm (51) are connected to the output connection plate (55) and the base respectively through flexible hinges. The upper and lower ends of the rear clamping arm (52) are connected to the output connection plate (55) and the base respectively through flexible hinges.

5. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 4, characterized in that, The front clamping arm (51) is a rigid beam, and a hollow slit is provided in the upper middle section to form a hollow slit rigid beam (511); the front clamping arm (51) is connected to the end of the lever-type hinge (1) near the bottom through a flexible hinge; The rear clamping arm (52) is formed by symmetrical arrangement of a left flexible plate (522) and a right flexible plate (523) to form an X-shaped non-cross structure. The upper end of the left flexible plate (522) and the lower end of the right flexible plate (523) are respectively fixedly connected to an upper rigid connecting beam (524) and a lower rigid connecting beam (525). The upper rigid connecting beam (524) is connected to the output connecting plate (55) through a flexible hinge, and the lower rigid connecting beam (525) is connected to the base through a flexible hinge. The middle stress-bearing sections of the left flexible plate (522) and the right flexible plate (523) are respectively connected to the variable stiffness adjustment mechanism (6).

6. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 5, characterized in that, The variable stiffness adjustment mechanism (6) includes two L-shaped lever hinges. One end of each L-shaped lever hinge is connected to the output end of the corresponding side piezoelectric ceramic actuator (31), and the other end is rigidly connected to the middle force-bearing section of the left and right side flexible plates of the rear clamping arm (52) through a double-layer elastic sheet.

7. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 2, characterized in that, The first clamping finger (53) and the second clamping finger (54) extending from the top of the base rear plate (7) together constitute the clamping jaws of the micro gripper, and the output connecting plate (55) is parallel to the bottom crossbeam (72) of the base.

8. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 1, characterized in that, A single-layer piezoelectric self-sensing actuator (8) is rigidly attached to the side of the first clamping finger (53) away from the second clamping finger (54).

9. The adjustable stiffness micro-clamping device with envelope clamping characteristics according to claim 1, characterized in that, The second clamping finger (54) includes a double-layer substrate arranged in parallel. The double-layer substrate is separated into upper and lower sections by a double-layer substrate connecting hinge (541). The upper and lower sections are respectively embedded with piezoelectric fiber actuators (9). The piezoelectric fiber actuators (9) are arranged along the length of the clamp. The second clamping finger (54) is connected to the top of the base side wall through an L-shaped support rod (10). A piezoelectric fiber actuator (9) is also embedded in a section of the interlayer connecting the L-shaped support rod (10) and the second clamping finger (54) to control the bending degree of the L-shaped support rod (10).

10. An adjustable stiffness micro-clamping method with envelope clamping characteristics, characterized in that, The adjustable stiffness micro-clamping device with envelope clamping characteristics as described in any one of claims 1-9 comprises the following steps: The piezoelectric ceramic actuator at the bottom of the base is subjected to excitation voltage and undergoes axial micro-elongation. After being amplified by the lever-type hinge (1), it pushes the flexible clamping arm (5) to move in the same direction from its upper end, driving the output connecting plate (55) to translate, and causing the first clamping finger (53) to move and open. The piezoelectric ceramic actuator on the side drives the variable stiffness adjustment mechanism (6) to apply force to the flexible clamping arm (5), changing the degree of bending of the flexible clamping arm (5). The first clamping finger (53) and the second clamping finger (54) adjust their posture so that the clamping end face of the two clamping fingers fits against the surface of the micro-object.

Images