A two-finger 5-DOF piezoelectric micro-gripper and its driving method

Abstract

A two-finger 5-DOF piezoelectric microgripper and its driving method belong to the field of micro-nano manipulation technology, and particularly relate to a two-finger 5-DOF piezoelectric microgripper and its driving method. This device addresses the problem of existing piezoelectric microgrippers being unable to achieve multi-DOF (greater than 3 DOF) manipulation while maintaining both a large travel range and high precision, thus failing to meet the requirements for flexible manipulation. The gripper comprises two three-dimensional piezoelectric actuators, two two-dimensional parallelogram flexible structures, multiple parallelism adjustment piezoelectric plates, and structural support components. The two-finger 5-DOF piezoelectric microgripper and its driving method are suitable for high-precision gripping and 5-DOF manipulation of micro-objects, and have broad application prospects in fields such as biomedicine, life sciences, precision manufacturing, microassembly, and advanced optics.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano operation technology, and in particular to a two-finger 5-DOF piezoelectric micro-gripper and a driving method thereof. Background Art

[0002] The rapid development of life sciences, advanced optics, precision engineering and other fields has put forward more stringent requirements on micro-nano operation technology, which requires not only flexible operation but also high-precision operation.

[0003] As the end effector for micro- and nano-manipulation tasks, microgrippers must possess a large travel range, high precision, and multiple degrees of freedom. Currently, microgrippers are categorized by their drive method into three main types: electrostatic, electromagnetic, electrothermal, and piezoelectric.

[0004] Among them, piezoelectric microgrippers have the advantages of fast response speed, high precision, low energy consumption, compact structure, predictable output displacement and no interference from magnetic fields. They are more suitable for scenarios that require high-precision operations on micro objects, such as biological micromanipulation, including cell separation, cell sorting, cell stiffness measurement, etc., or optical switching assembly based on MEMS chips, or assembly of micro components on chip substrates.

[0005] The typical configuration of existing piezoelectric microgrippers is a piezoelectric stack with a flexible amplification mechanism, which can achieve long travel and high-precision operation. However, this typical configuration is limited by the piezoelectric stack's ability to output only one-dimensional linear displacement, making it difficult to achieve multi-degree-of-freedom operation. Existing piezoelectric microgrippers generally operate with a single degree of freedom. In rare cases, 2-DOF (i.e., two degrees of freedom) can be achieved by increasing the number of piezoelectric stacks. However, achieving higher degrees of freedom remains difficult for those skilled in the art, and is far from sufficient to meet the requirements for flexible operation. Summary of the Invention

[0006] The present invention proposes a two-finger 5-DOF piezoelectric micro-gripper and a driving method thereof, which solves the problem that existing piezoelectric micro-grippers cannot achieve multi-degree-of-freedom (greater than 3 degrees of freedom) operation while taking into account a large stroke and high precision, and thus cannot meet the requirements of flexible operation.

[0007] The technical solution of the dual-finger 5-DOF piezoelectric micro-gripper described in the present invention is as follows:

[0008] The clamp includes: two three-dimensional piezoelectric actuators, two two-dimensional parallelogram flexible structures, a plurality of parallelism adjustment piezoelectric sheets and a structural support component;

[0009] The bottom of each three-dimensional piezoelectric actuator is fixed to the structural support component, and the top of each three-dimensional piezoelectric actuator is fixedly connected to the input end of a two-dimensional parallelogram flexible structure; the three-dimensional piezoelectric actuator is used to generate original output displacements along the X-axis, Y-axis and Z-axis respectively;

[0010] The fixed end of each two-dimensional parallelogram flexible structure is fixedly connected to the structural support component, and the top end thereof is a fingertip; the top end of the fingertip is a contact surface, and the contact surfaces of the two fingertips are arranged opposite to each other;

[0011] The two-dimensional parallelogram flexible structure is used to transmit the original output displacement of the three-dimensional piezoelectric actuator along the Z axis to the fingertip output, and amplify and guide the original output displacement of the three-dimensional piezoelectric actuator along the X axis and Y axis, so that the fingertip obtains the final output displacement along the X axis, Y axis and Z axis.

[0012] The fingertips of the two two-dimensional parallelogram flexible structures are used to achieve clamping and opening actions under the coordination of the final output displacements along the X-axis direction, the Y-axis direction, and the Z-axis direction, and to operate the micro-object to move along the X-axis direction, the Y-axis direction, and the Z-axis direction, rotate about the Z-axis direction, and deflect about the Y-axis direction;

[0013] The parallelism adjustment piezoelectric sheet is pasted on the surface of the two-dimensional parallelogram flexible structure and is used to adjust the parallelism between the end contact surfaces of the fingertips of the two two-dimensional parallelogram flexible structures.

[0014] Furthermore, a preferred embodiment is provided, wherein the three-dimensional piezoelectric actuator comprises: a stacked pre-tightening screw, a bridge-type amplification structure, a piezoelectric stack, and a bending drive module;

[0015] The piezoelectric stack is embedded in the bridge-type amplifier structure, and a stack pre-tightening screw is used to provide a given pre-tightening force to provide a driving displacement along the X-axis direction;

[0016] The bottom of the bridge-type amplification structure is fixed to the structural support component, and the top of the bridge-type amplification structure is fixedly connected to the bottom of the bending drive module; the bridge-type amplification structure is used to amplify and guide the driving displacement provided by the piezoelectric stack along the X-axis direction to obtain the original output displacement along the Z-axis direction;

[0017] The top of the bending drive module is fixedly connected to the input end of a two-dimensional parallelogram flexible structure; the bending drive module is used to provide an original output displacement along the X-axis direction and an original output displacement along the Y-axis direction according to the piezoelectric effect.

[0018] Furthermore, a preferred embodiment is provided, wherein the bending drive module comprises: a bottom end cover, a plurality of four-partition piezoelectric ceramics, a plurality of four-partition electrode sheets, a plurality of ground electrode sheets, a top end cover, and a No. 2 pre-tightening screw;

[0019] The bottom end cover, multiple four-partition piezoelectric ceramics, multiple four-partition electrode sheets, multiple ground electrode sheets, and the top end cover are stacked in sequence from bottom to top along the Z-axis direction and fixed with No. 2 pre-tightening screws; the top of the top end cover is fixedly connected to the input end of a two-dimensional parallelogram flexible structure;

[0020] Every two partitions of the four-partition piezoelectric ceramic are grouped together, with one group of partitions being arranged opposite to each other along the X-axis direction, and the other group of partitions being arranged opposite to each other along the Y-axis direction;

[0021] An excitation signal is used to excite a group of partitions of all four-partition piezoelectric ceramics to cause the bending drive module to bend and deform along the X-axis direction, thereby obtaining an original output displacement along the X-axis direction;

[0022] An excitation signal is used to excite another group of partitions of all four-partition piezoelectric ceramics, so as to make the bending drive module bend and deform along the Y-axis direction, thereby obtaining the original output displacement along the Y-axis direction.

[0023] Furthermore, a preferred embodiment is provided in which the polarization directions of two partitions of the same group of partitions of the four-partition piezoelectric ceramic are opposite.

[0024] Furthermore, a preferred embodiment is provided, wherein the fixed end of the two-dimensional parallelogram flexible structure is fixedly connected to the structural support member;

[0025] The input end of the two-dimensional parallelogram flexible structure is fixedly connected to the top of the three-dimensional piezoelectric actuator;

[0026] The top end output end of the two-dimensional parallelogram flexible structure is a fingertip;

[0027] The two-dimensional parallelogram flexible structure is used to guide the original output displacements generated by the three-dimensional piezoelectric actuator along the X-axis, Y-axis, and Z-axis directions by utilizing the characteristics of the parallelogram being unstable and easily deformed, and having its opposite sides always remaining parallel; it is also used to amplify the original output displacements generated by the three-dimensional piezoelectric actuator along the X-axis and Y-axis directions by utilizing the principle of leverage; and it is also used to decouple the final output displacements along the X-axis, Y-axis, and Z-axis directions by utilizing the characteristic that the longitudinal stiffness of the flexible hinge is much greater than the lateral stiffness.

[0028] Furthermore, a preferred embodiment is provided, wherein the fingertip includes a connecting end at the bottom end, a connecting column at the bottom, a transverse beam in the middle, a thin beam structure at the top, and a clamping column at the top end; the end of the clamping column is a contact surface.

[0029] Furthermore, a preferred embodiment is provided, wherein the plurality of parallelism adjustment piezoelectric sheets are adhered to the fingertip surface of the two-dimensional parallelogram flexible structure to adjust the parallelism between the contact surfaces of the fingertips.

[0030] Furthermore, a preferred embodiment is provided, wherein the clamp further comprises a strain gauge;

[0031] The strain gauge is attached to the thin beam structure of the fingertip and is used to measure the clamping force and provide feedback.

[0032] Further, a preferred embodiment is provided, wherein the structural support component includes a packaging cover, an outer shell and an inner shell;

[0033] The inner shell includes a circular flat plate at the bottom and a cubic support column located in the center of the circular flat plate;

[0034] Two three-dimensional piezoelectric actuators are symmetrically fixed on the circular plate;

[0035] Two two-dimensional parallelogram flexible structures are symmetrically arranged on both sides of the cubic support column and are respectively fixedly connected to one side of the cubic support column;

[0036] The bottom end surface of the housing is fixedly arranged on the circular flat plate, and the top end surface thereof is fixedly connected to the packaging cover;

[0037] One side planar inner wall of the shell is located on one side of a two-dimensional parallelogram flexible structure, and the two are fixedly connected;

[0038] The other side of the inner plane wall of the shell is located on one side of another two-dimensional parallelogram flexible structure, and the two are fixedly connected.

[0039] The present invention also proposes a driving method for a two-finger 5-DOF piezoelectric micro-gripper, the technical solution of which is as follows:

[0040] The driving method is used to drive the above-mentioned two-finger 5-DOF piezoelectric micro-gripper to achieve the clamping and opening actions of the contact surfaces of the two fingertips, and to operate the micro-object to move along the X-axis, Y-axis and Z-axis, rotate around the Z-axis and deflect around the Y-axis.

[0041] The driving method shown includes the following steps:

[0042] Step 1: The original output displacements of the two 3D piezoelectric actuators along the X-axis are stimulated to move in opposite directions and toward each other, causing the contact surfaces of the two fingertips to open, thereby placing a micro-object between the two contact surfaces or releasing a clamped micro-object.

[0043] Step 2: The original output displacements of the two 3D piezoelectric actuators along the X-axis are driven in opposite directions and away from each other, closing the contact surfaces of the two fingertips to grip the micro-object.

[0044] Step 3: The original output displacements of the two 3D piezoelectric actuators along the X-axis are driven in the same direction, causing the contact surfaces of the two fingertips to move in the same direction along the X-axis. The movement direction is opposite to the direction of the original output displacement along the X-axis, which is used to manipulate the micro-object to move along the X-axis.

[0045] Step 4: The original output displacements of the two three-dimensional piezoelectric actuators along the Y-axis are driven in the same direction, causing the contact surfaces of the two fingertips to move in the same direction along the Y-axis. The movement direction is opposite to the direction of the original output displacement along the Y-axis, which is used to manipulate the micro-object to move along the Y-axis.

[0046] Step 5: The original output displacements of the two three-dimensional piezoelectric actuators along the Z axis are driven in the same direction, causing the contact surfaces of the two fingertips to move in the same direction along the Z axis. The movement direction is the same as the direction of the original output displacement along the Z axis, which is used to manipulate the micro-object to move along the Z axis.

[0047] Step 6: The original output displacements of the two 3D piezoelectric actuators along the Y-axis are driven in opposite directions, causing the contact surfaces of the two fingertips to move in opposite directions along the Y-axis, thereby twisting the micro-object to rotate around the Z-axis.

[0048] Step 7: Stimulate the original output displacements of the two three-dimensional piezoelectric actuators along the X-axis direction in opposite directions and drive them away from each other. At the same time, only stimulate the original output displacement of any one of the three-dimensional piezoelectric actuators along the Z-axis direction, so that the contact surfaces of the two fingertips are closed and displaced along the Z-axis direction, which is used to twist the micro-object and deflect it around the Y-axis direction.

[0049] The present invention has the following beneficial effects:

[0050] 1. The dual-finger 5-DOF piezoelectric microgripper described in the present invention utilizes a three-dimensional piezoelectric actuator for three-dimensional drive, amplifies and guides displacement in the X and Y directions through a two-dimensional parallelogram flexible structure, and decouples displacement in the Z direction. It has the advantages of fast response speed, high precision, low energy consumption, compact structure, predictable output displacement, and immunity to magnetic field interference.

[0051] 2. The dual-finger 5-DOF piezoelectric micro-gripper described in the present invention uses a parallelism adjustment piezoelectric sheet to adjust the parallelism of the end contact surfaces in real time, so that the relative movement of the two contact surfaces always remains parallel, achieving parallel and stable clamping and preventing the clamped object from loosening.

[0052] The two-finger 5-DOF piezoelectric micro-gripper and its driving method described in the present invention are suitable for high-precision clamping and 5-DOF operation of micro-objects, and have broad application prospects in biomedicine, life sciences, precision manufacturing, micro-assembly, advanced optics and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 Figure 1 is a schematic diagram of the structure of a two-finger 5-DOF piezoelectric microgripper according to one embodiment of the present invention; (a) is a schematic diagram of the appearance of the piezoelectric microgripper; (b) is a top view of the piezoelectric microgripper with the packaging cover removed; (c) is a schematic diagram of the structure of the piezoelectric microgripper with the outer shell cut away;

[0055] Figure 2 Schematic diagram of the structure of a three-dimensional piezoelectric actuator in one embodiment of the present invention;

[0056] Figure 3 A schematic diagram of a four-partition piezoelectric ceramic in one embodiment of the present invention;

[0057] Figure 4 Schematic diagram of the principle of a three-dimensional piezoelectric actuator in one embodiment of the present invention; (a) is a schematic diagram of the bridge-type amplification structure amplifying and guiding the driving displacement provided by the piezoelectric stack along the X-axis (to obtain the original output displacement along the Z-axis); (b) is a schematic diagram of the original output displacement provided by the bending drive module along the X (Y) axis;

[0058] Figure 5 This is a schematic diagram of a two-dimensional parallelogram flexible structure in one embodiment of the present invention;

[0059] Figure 6 Schematic diagram of the guiding and amplifying principle of a two-dimensional parallelogram flexible structure in one embodiment of the present invention; (a) illustrates the guiding and amplifying effect on the original output displacement along the X-axis; (b) illustrates the guiding and amplifying effect on the original output displacement along the Y-axis; and (c) illustrates the guiding effect on the original output displacement along the Z-axis.

[0060] Figure 7 Schematic diagram of the clamping and opening actions of the contact surfaces of two fingertips in one embodiment of the present invention; wherein (a) is the clamping action, and (b) is the opening action;

[0061] Figure 8 Schematic diagram of the principle of five-degree-of-freedom operation in one embodiment of the present invention; wherein (a) is movement along the X-axis, (b) is movement along the Y-axis, (c) is movement along the Z-axis, (d) is rotation about the Z-axis, and (e) is deflection about the Y-axis;

[0062] Figure 9 A schematic diagram of the principle of adjusting the parallelism of a parallelism-adjusting piezoelectric piece in one embodiment of the present invention;

[0063] Reference numerals:

[0064] 1. Three-dimensional piezoelectric actuator; 1-1. Stack pre-tightening screw; 1-2. Bridge amplification structure; 1-3. Piezoelectric stack; 1-4. Bending drive module; 1-4-1. Bottom cover; 1-4-2. Four-partition piezoelectric ceramic; 1-4-3. Four-partition electrode sheet; 1-4-4. Ground electrode sheet; 1-4-5. Top cover; 1-4-6. No. 2 pre-tightening screw; 2. Two-dimensional parallelogram flexible structure; 2-1. Pillar; 2-2. Flexible hinge; 2-3. Fingertip; 2-3-1. Connecting end; 2-3-2. Connecting column; 2-3-3. Transverse beam; 2-3-4. Thin beam structure; 2-3-5. Clamping column; 3. Parallelism adjustment piezoelectric sheet; 4. Strain gauge; 5. Structural support component; 5-1. Packaging cover; 5-2. Outer shell; 5-3. Inner shell. DETAILED DESCRIPTION

[0065] In order to make the technical solutions and advantages of the present invention more clearly described, the specific embodiments of the present invention will be further described in detail and completely in conjunction with the accompanying drawings. The various embodiments described below are only part of the preferred embodiments of the present invention, rather than all implementation plans; the various embodiments described below are intended to explain the present invention and cannot be understood as limiting the present invention; the reasonable combination of the technical features defined in the various embodiments of the present invention, as well as all other implementation plans obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work, all fall within the scope of protection of the present invention.

[0066] Implementation Method 1: Combination Figures 1 to 9 This embodiment provides a two-finger 5-DOF piezoelectric micro-gripper. The specific implementation contents are as follows:

[0067] The clamp includes: two three-dimensional piezoelectric actuators 1, two two-dimensional parallelogram flexible structures 2, a plurality of parallelism adjustment piezoelectric sheets 3 and a structural support component 5;

[0068] The bottom of each three-dimensional piezoelectric actuator 1 is fixed to the structural support component 5, and the top is fixedly connected to the input end of a two-dimensional parallelogram flexible structure 2; the three-dimensional piezoelectric actuator 1 is used to generate original output displacements along the X-axis, Y-axis and Z-axis respectively;

[0069] The fixed end of each two-dimensional parallelogram flexible structure 2 is fixedly connected to the structural support component 5, and the top end thereof is a fingertip 2-3; the top end of the fingertip 2-3 is a contact surface, and the contact surfaces of the two fingertips 2-3 are arranged opposite to each other;

[0070] The two-dimensional parallelogram flexible structure 2 is used to transmit the original output displacement of the three-dimensional piezoelectric actuator 1 along the Z axis to the fingertips 2-3 for output, and amplify and guide the original output displacement of the three-dimensional piezoelectric actuator 1 along the X axis and Y axis, so that the fingertips 2-3 obtain the final output displacement along the X axis, Y axis and Z axis.

[0071] The fingertips 2-3 of the two two-dimensional parallelogram flexible structures 2 are used to achieve clamping and opening actions, and to operate the micro-object to move along the X-axis, Y-axis and Z-axis, rotate around the Z-axis and deflect around the Y-axis, under the coordination of the final output displacement along the X-axis, Y-axis and Z-axis directions;

[0072] The parallelism adjustment piezoelectric sheet 3 is attached to the surface of the two-dimensional parallelogram flexible structure 2 and is used to adjust the parallelism between the end contact surfaces of the fingertips 2 - 3 of the two two-dimensional parallelogram flexible structures 2 .

[0073] In this embodiment, the 5-DOF (5 degrees of freedom) motion includes: movement along the X-axis (positive and negative directions), the Y-axis (positive and negative directions) and the positive direction of the Z-axis, rotation around the Z-axis and deflection around the Y-axis.

[0074] In this embodiment, if Figure 1 As shown, the positive direction of the X-axis is horizontally toward the right; the positive direction of the Y-axis is horizontally toward the rear; and the positive direction of the Z-axis is vertically upward.

[0075] In this embodiment, the original output displacement along the Z-axis direction will not be amplified and guided by the two-dimensional parallelogram flexible structure 2; therefore, the original output displacement along the Z-axis direction and the final output displacement along the Z-axis direction are the same in displacement amount and direction.

[0076] In this embodiment, the original output displacement along the X-axis direction will be amplified and guided by the two-dimensional parallelogram flexible structure 2; therefore, the original output displacement along the X-axis direction and the final output displacement along the X-axis direction are different in displacement amount and direction; the displacement amount of the final output displacement along the X-axis direction is greater than the displacement amount of the original output displacement along the X-axis direction; the direction of the final output displacement along the X-axis direction is opposite to the direction of the original output displacement along the X-axis direction. If the direction of the original output displacement along the X-axis direction is the positive direction along the X-axis direction, the direction of the final output displacement along the X-axis direction is the negative direction along the X-axis direction.

[0077] In this embodiment, the original output displacement along the Y-axis direction will be amplified and guided by the two-dimensional parallelogram flexible structure 2; therefore, the original output displacement along the Y-axis direction and the final output displacement along the Y-axis direction are different in displacement amount and direction; the displacement amount of the final output displacement along the Y-axis direction is greater than the displacement amount of the original output displacement along the Y-axis direction; the direction of the final output displacement along the Y-axis direction is opposite to the direction of the original output displacement along the Y-axis direction. If the direction of the original output displacement along the Y-axis direction is the positive direction along the Y-axis direction, the direction of the final output displacement along the Y-axis direction is the negative direction along the Y-axis direction.

[0078] In this embodiment, the pinching and opening action of the two fingertips 2 - 3 refers to the pinching and opening of the contact surfaces of the two fingertips 2 - 3 .

[0079] In this embodiment, the two fingertips 2 - 3 form a double-finger structure by providing contact surfaces and arranging the two contact surfaces opposite to each other.

[0080] Implementation Method 2: Combination Figures 1 to 9 This embodiment further defines the dual-finger 5-DOF piezoelectric micro-gripper described in Embodiment 1. The specific implementation contents are as follows:

[0081] The three-dimensional piezoelectric actuator 1 includes: a stacked pre-tightening screw 1-1, a bridge-type amplification structure 1-2, a piezoelectric stack 1-3 and a bending drive module 1-4;

[0082] The piezoelectric stack 1-3 is embedded in the bridge-type amplifying structure 1-2, and uses the stack pre-tightening screw 1-1 to provide a given pre-tightening force, so as to provide a driving displacement along the X-axis direction;

[0083] The bottom of the bridge amplification structure 1-2 is fixed to the structural support component 5, and the top of the bridge amplification structure 1-2 is fixedly connected to the bottom of the bending drive module 1-4. The bridge amplification structure 1-2 is used to amplify and guide the driving displacement provided by the piezoelectric stack 1-3 along the X-axis direction to obtain the original output displacement along the Z-axis direction.

[0084] The top of the bending driving module 1-4 is fixedly connected to the input end of a two-dimensional parallelogram flexible structure 2; the bending driving module 1-4 is used to provide the original output displacement along the X-axis direction and the original output displacement along the Y-axis direction according to the piezoelectric effect.

[0085] In this embodiment, when the piezoelectric stack 1-3 stretches under the stimulation of the voltage excitation signal (i.e., generates a driving displacement along the X-axis direction), the bridge-type amplification structure 1-2 stretches laterally and widens longitudinally, outputting the original output displacement along the Z-axis direction. According to the amplification principle, the displacement of the original output displacement along the Z-axis direction is greater than the displacement of the driving displacement along the X-axis direction.

[0086] In this embodiment, the original output displacement along the Z-axis direction obtained by the bridge-type amplification structure 1-2 is transmitted to the two-dimensional parallelogram flexible structure 2 through the bending drive module 1-4 to obtain the final output displacement along the Z-axis direction (compared with the original output displacement, the displacement amount and direction remain unchanged).

[0087] Implementation Method 3: Combination Figures 1 to 9 This embodiment is described as a further limitation of the two-finger 5-DOF piezoelectric micro-gripper described in the second embodiment. The specific implementation contents are as follows:

[0088] The bending drive module 1-4 includes: a bottom end cover 1-4-1, a plurality of four-partition piezoelectric ceramics 1-4-2, a plurality of four-partition electrode sheets 1-4-3, a plurality of grounding electrode sheets 1-4-4, a top end cover 1-4-5 and a No. 2 pre-tightening screw 1-4-6;

[0089] The bottom end cover 1-4-1, multiple four-partition piezoelectric ceramics 1-4-2, multiple four-partition electrode sheets 1-4-3, multiple ground electrode sheets 1-4-4, and the top end cover 1-4-5 are stacked in sequence from bottom to top along the Z-axis direction and fixed with No. 2 pre-tightening screws 1-4-6; the top of the top end cover 1-4-5 is fixedly connected to the input end of a two-dimensional parallelogram flexible structure 2;

[0090] Every two partitions of the four-partition piezoelectric ceramics 1-4-2 are grouped together, with one group of partitions being arranged opposite to each other along the X-axis direction, and the other group of partitions being arranged opposite to each other along the Y-axis direction;

[0091] An excitation signal is used to excite a group of partitions of all four-partition piezoelectric ceramics 1-4-2, so as to cause the bending drive module 1-4 to bend and deform along the X-axis direction, thereby obtaining an original output displacement along the X-axis direction;

[0092] An excitation signal is used to excite another group of partitions of all four-partition piezoelectric ceramics 1-4-2, so as to make the bending drive module 1-4 bend and deform along the Y-axis direction, thereby obtaining the original output displacement along the Y-axis direction.

[0093] Furthermore, a preferred embodiment is provided, in which for a plurality of stacked four-partition piezoelectric ceramics 1-4-2, the partitions of two upper and lower adjacent four-partition piezoelectric ceramics 1-4-2 correspond one to one, and the polarization directions of the two partitions in the same position area are opposite.

[0094] Furthermore, a preferred embodiment is provided in which the polarization directions of two partitions of the same group of partitions of the four-partition piezoelectric ceramic 1-4-2 are opposite.

[0095] Implementation Method 4: Combination Figures 1 to 9 This embodiment further defines the dual-finger 5-DOF piezoelectric micro-gripper described in Embodiment 1. The specific implementation contents are as follows:

[0096] The fixed end of the two-dimensional parallelogram flexible structure 2 is fixedly connected to the structural support component 5;

[0097] The input end of the two-dimensional parallelogram flexible structure 2 is fixedly connected to the top of the three-dimensional piezoelectric actuator 1;

[0098] The top end output end of the two-dimensional parallelogram flexible structure 2 is a fingertip 2-3;

[0099] The two-dimensional parallelogram flexible structure 2 is used to guide the original output displacements generated by the three-dimensional piezoelectric actuator 1 along the X-axis, Y-axis and Z-axis directions by utilizing the characteristics of the parallelogram being unstable and easily deformed and the opposite sides always remaining parallel; it is also used to amplify the original output displacements generated by the three-dimensional piezoelectric actuator 1 along the X-axis and Y-axis directions by utilizing the lever principle; it is also used to achieve decoupling of the final output displacements along the X-axis, Y-axis and Z-axis directions by utilizing the characteristic that the longitudinal stiffness of the flexible hinge is much greater than the lateral stiffness.

[0100] In this embodiment, each two-dimensional parallelogram flexible structure is mainly composed of an input end, four parallel pillars 2-1, a flexible hinge 2-2 and a fingertip 2-3;

[0101] The bottom of each column 2-1 is connected to the input end via a flexible hinge 2-2 arranged along the Z-axis direction;

[0102] The fixed end of the side surface of the bottom of each column 2-1 is connected to the structural support component 5 through a flexible hinge 2-2 arranged along the X-axis direction;

[0103] The top of each pillar 2-1 is connected to the fingertip 2-3 via a flexible hinge 2-2 arranged along the Z-axis direction.

[0104] In this embodiment, the pillar 2 - 1 and the input end are equivalent to rigid bodies in theoretical modeling.

[0105] In this embodiment, each two-dimensional parallelogram flexible structure is driven by a corresponding three-dimensional piezoelectric actuator, so each two-dimensional parallelogram flexible structure can independently output the final output displacement along the X-axis direction (positive and negative directions), the Y-axis direction (positive and negative directions) and the positive direction of the Z-axis.

[0106] In this embodiment, a two-dimensional parallelogram flexible structure utilizes the characteristic of flexible hinges having longitudinal stiffness far greater than lateral stiffness to achieve decoupling of three-dimensional motion. It also utilizes the lever and parallelogram principles to achieve displacement amplification and guidance. Specifically, when an X-direction displacement is input to the input end of the two-dimensional parallelogram flexible structure, the flexible hinges arranged along the X-axis, due to their high longitudinal stiffness, do not undergo significant deformation, thus acting as fixed fulcrums. The flexible hinges arranged along the Z-axis, due to their low lateral stiffness, undergo bending deformation, acting as a revolute pair. Based on the lever and parallelogram principles, the two-dimensional parallelogram flexible structure amplifies the input displacement and guides it to the fingertip for output, achieving X-direction motion. The same applies to the Y-direction. When a Z-direction displacement is input to the input end of the two-dimensional parallelogram flexible structure, the two flexible hinges arranged along the X-axis, due to their high longitudinal stiffness, do not undergo deformation, thus restricting the parallelogram structure's X-direction motion. However, due to their low lateral stiffness, they undergo bending deformation, not restricting the parallelogram structure's Z-direction motion, thus acting as a moving pair. The flexible hinges arranged along the Z direction do not deform due to their large longitudinal stiffness. Therefore, the two-dimensional parallelogram flexible structure is equivalent to a rigid body except for the two flexible hinges arranged along the X axis, which directly transmits the input displacement to the fingertips to achieve Z-direction motion output.

[0107] Implementation Method 5: Combination Figures 1 to 9 This embodiment further defines the dual-finger 5-DOF piezoelectric micro-gripper described in Embodiment 1. The specific implementation contents are as follows:

[0108] The fingertip 2-3 includes a connecting end 2-3-1 at the bottom end, a connecting column 2-3-2 at the bottom, a transverse beam 2-3-3 in the middle, a thin beam structure 2-3-4 at the top and a clamping column 2-3-5 at the top end; the end of the clamping column 2-3-5 is a contact surface.

[0109] In this embodiment, the contact surface is used to contact with the micro-object to achieve 5-DOF manipulation.

[0110] In this embodiment, the transverse beam 2-3-3 and the thin beam structure 2-3-4 of the fingertip 2-3 are flexible structures such as flexible hinges. The other parts of the fingertip 2-3 are equivalent to rigid bodies in theoretical modeling.

[0111] Implementation Method 6: Combination Figures 1 to 9This embodiment further defines the dual-finger 5-DOF piezoelectric micro-gripper described in Embodiment 1. The specific implementation contents are as follows:

[0112] The plurality of parallelism adjustment piezoelectric sheets 3 are adhered to the surfaces of the fingertips 2 - 3 of the two-dimensional parallelogram flexible structure 2 to adjust the parallelism between the contact surfaces of the fingertips 2 - 3 .

[0113] Further, a preferred embodiment is provided.

[0114] The plurality of parallelism adjustment piezoelectric sheets 3 are divided into two groups:

[0115] A set of transverse beams 2-3-3 symmetrically attached to the upper and lower sides of the fingertips 2-3 is used to adjust the parallelism of the contact surfaces of the two fingertips 2-3 ends in the XZ plane;

[0116] A set of symmetrically attached to the front and rear sides of the transverse beam 2-3-3 of the fingertips 2-3 is used to adjust the parallelism of the contact surfaces of the end portions of the two fingertips 2-3 in the XY plane.

[0117] In this embodiment, the upper and lower sides of the transverse beam are the two sides along the Z-axis direction.

[0118] In this embodiment, the front and rear sides of the transverse beam are both sides along the Y-axis direction.

[0119] In this embodiment, the XZ plane refers to a plane parallel to the X axis and the Z axis.

[0120] In this embodiment, the XY plane refers to a plane parallel to the X-axis and the Y-axis.

[0121] In this embodiment, the piezoelectric plates on the upper and lower sides of the horizontal beam attached to the fingertip shorten and lengthen under the stimulation of the voltage excitation signal, causing the contact surface at the end of the fingertip to rotate a certain angle around the Y axis, which is used to adjust the parallelism of the two contact surfaces in the XZ plane.

[0122] In this embodiment, the piezoelectric plates on the front and rear sides of the horizontal beam attached to the fingertip shorten and lengthen under the stimulation of the voltage excitation signal, causing the contact surface at the end of the fingertip to rotate a certain angle around the Z axis, which is used to adjust the parallelism of the two contact surfaces in the XY plane.

[0123] In this embodiment, the piezoelectric sheet 3 is adjusted in parallel so that the two contact surfaces of the clamper and the manipulated micro-object are always kept parallel, thereby achieving stable parallel clamping and reducing stress concentration.

[0124] Implementation Method VII: Combination Figures 1 to 9 This embodiment is described as a further limitation of the dual-finger 5-DOF piezoelectric micro-gripper described in Embodiment 5. The specific implementation contents are as follows:

[0125] The clamp further includes a strain gauge 4;

[0126] The strain gauge 4 is attached to the thin beam structure 2-3-4 of the fingertip 2-3 and is used to measure the clamping force and provide feedback.

[0127] In this embodiment, the clamping force is measured and fed back by the strain gauge 4 , and the magnitude of the clamping force is further adjusted according to the measurement result.

[0128] Implementation Method 8: Combination Figures 1 to 9 This embodiment further defines the dual-finger 5-DOF piezoelectric micro-gripper described in Embodiment 1. The specific implementation contents are as follows:

[0129] The structural support component 5 includes a packaging cover 5-1, an outer shell 5-2 and an inner shell 5-3;

[0130] The inner shell 5-3 includes a circular flat plate at the bottom and a cubic support column located in the center of the circular flat plate;

[0131] Two three-dimensional piezoelectric actuators 1 are symmetrically fixed on the circular plate;

[0132] Two two-dimensional parallelogram flexible structures 2 are symmetrically arranged on both sides of the cubic support column and are respectively fixedly connected to one side of the cubic support column;

[0133] The bottom end surface of the housing 5-2 is fixedly arranged on a circular flat plate, and the top end surface thereof is fixedly connected to the packaging cover 5-1;

[0134] One side planar inner wall of the housing 5-2 is located on one side of a two-dimensional parallelogram flexible structure 2, and the two are fixedly connected;

[0135] The other side planar inner wall of the shell 5 - 2 is located on one side of another two-dimensional parallelogram flexible structure 2 , and the two are fixedly connected.

[0136] In this embodiment, the cubic support column is a hollow cube.

[0137] Implementation Method 9: Combination Figures 1 to 9 This embodiment provides a driving method for a two-finger 5-DOF piezoelectric micro-gripper. The specific implementation contents are as follows:

[0138] The driving method is used to drive a two-finger 5-DOF piezoelectric micro-gripper described in the above embodiment to achieve the clamping and opening actions of the contact surfaces of the two fingertips 2-3, and to operate the micro-object to move along the X-axis, Y-axis and Z-axis, rotate about the Z-axis and deflect about the Y-axis;

[0139] The driving method shown includes the following steps:

[0140] Step 1: Exciting the original output displacements of the two three-dimensional piezoelectric actuators 1 along the X-axis direction in opposite directions and driving them toward each other, so that the contact surfaces at the ends of the two fingertips 2-3 are opened, so as to place the micro-object between the two contact surfaces or to release the clamped micro-object;

[0141] Step 2: Exciting the original output displacements of the two three-dimensional piezoelectric actuators 1 along the X-axis direction in opposite directions and driving away from each other, so that the contact surfaces of the two fingertips 2-3 are closed to clamp the micro-object;

[0142] Step 3: The original output displacements of the two three-dimensional piezoelectric actuators 1 along the X-axis are driven in the same direction, so that the contact surfaces of the two fingertips 2-3 move in the same direction along the X-axis. The movement direction is opposite to the direction of the original output displacement along the X-axis, so as to manipulate the micro-object to move along the X-axis.

[0143] Step 4: The original output displacements of the two three-dimensional piezoelectric actuators 1 along the Y-axis are driven in the same direction, so that the contact surfaces of the two fingertips 2-3 move in the same direction along the Y-axis. The movement direction is opposite to the direction of the original output displacement along the Y-axis, so as to manipulate the micro-object to move along the Y-axis.

[0144] Step 5: The original output displacements of the two three-dimensional piezoelectric actuators 1 along the Z-axis are driven in the same direction, so that the contact surfaces of the two fingertips 2-3 move in the same direction along the Z-axis. The movement direction is the same as the direction of the original output displacement along the Z-axis, which is used to manipulate the micro-object to move along the Z-axis.

[0145] Step 6: The original output displacements of the two three-dimensional piezoelectric actuators 1 along the Y-axis are driven in opposite directions, so that the contact surfaces of the two fingertips 2-3 move in opposite directions along the Y-axis, respectively, to twist the micro-object and rotate it around the Z-axis.

[0146] Step 7: Stimulate the original output displacements of the two three-dimensional piezoelectric actuators 1 along the X-axis direction in opposite directions and drive them away from each other, and at the same time only stimulate the original output displacement of any one of the three-dimensional piezoelectric actuators 1 along the Z-axis direction, so that the end contact surfaces of the two fingertips 2-3 are closed and displaced along the Z-axis direction, which is used to twist the micro-object and deflect it around the Y-axis direction.

[0147] In this embodiment, in step 3:

[0148] If the original output displacements of the two three-dimensional piezoelectric actuators 1 along the X-axis are both driven in the positive direction of the X-axis, the contact surfaces of the two fingertip ends move in the opposite direction of the X-axis;

[0149] If the original output displacements of the two three-dimensional piezoelectric actuators 1 along the X-axis direction are both driven in the opposite direction of the X-axis direction, the contact surfaces of the two fingertip ends move in the positive direction of the X-axis direction.

[0150] In this embodiment, in step 4:

[0151] If the original output displacements of the two three-dimensional piezoelectric actuators 1 along the Y-axis are both driven in the positive direction of the Y-axis, the contact surfaces of the two fingertip ends move in the opposite direction of the Y-axis;

[0152] If the original output displacements of the two three-dimensional piezoelectric actuators 1 along the Y-axis direction are both driven in the opposite direction of the Y-axis direction, the contact surfaces of the two fingertip ends move in the positive direction of the Y-axis direction.

[0153] In this embodiment, in step 5:

[0154] Since the piezoelectric stack can only be stretched and deformed, the original output displacement in the Z direction can only be in the positive direction. That is, the original output displacements along the Z axis of the two three-dimensional piezoelectric actuators 1 are both driven in the positive direction of the Z axis, and the contact surfaces of the two fingertips move in the positive direction of the Z axis.

[0155] In this embodiment, in step 6:

[0156] If the original output displacements of the two three-dimensional piezoelectric actuators 1 along the Y-axis are driven in opposite directions, that is, one is driven in the positive direction of the Y-axis and the other is driven in the negative direction of the Y-axis, then one of the two fingertip end contact surfaces moves in the negative direction of the Y-axis and the other moves in the positive direction of the Y-axis, thereby twisting the micro-object to rotate clockwise or counterclockwise around the Z-axis.

[0157] The above further describes the technical solution provided by the present invention in detail through several specific embodiments in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific embodiments described above are not intended to limit the present invention. Any reasonable changes and improvements to the present invention, reasonable combinations of implementation methods and equivalent replacements based on the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A two-finger 5-DOF piezoelectric microgripper, characterized in that: The clamp comprises: two three-dimensional piezoelectric actuators (1), two two-dimensional parallelogram flexible structures (2), a plurality of parallelism adjustment piezoelectric sheets (3), and a structural support component (5); The bottom of each three-dimensional piezoelectric actuator (1) is fixed on a structural support component (5), and the top thereof is fixedly connected to the input end of a two-dimensional parallelogram flexible structure (2); the three-dimensional piezoelectric actuator (1) is used to generate original output displacements along the X-axis direction, the Y-axis direction, and the Z-axis direction respectively; The fixed end of each two-dimensional parallelogram flexible structure (2) is fixedly connected to the structural support component (5), and the top end thereof is a fingertip (2-3); the top end of the fingertip (2-3) is a contact surface, and the contact surfaces of the two fingertips (2-3) are arranged opposite to each other; The two-dimensional parallelogram flexible structure (2) is used to transmit the original output displacement of the three-dimensional piezoelectric actuator (1) along the Z-axis direction to the fingertip (2-3) for output, and to amplify and guide the original output displacement of the three-dimensional piezoelectric actuator (1) along the X-axis direction and the Y-axis direction, so that the fingertip (2-3) obtains the final output displacement along the X-axis direction, the Y-axis direction and the Z-axis direction; The fingertips (2-3) of the two two-dimensional parallelogram flexible structures (2) are used to realize clamping and opening actions in coordination with the final output displacements along the X-axis direction, the Y-axis direction and the Z-axis direction, and to operate the micro-object to move along the X-axis direction, the Y-axis direction and the Z-axis direction, rotate around the Z-axis direction and deflect around the Y-axis direction; The parallelism adjustment piezoelectric sheet (3) is adhered to the surface of the two-dimensional parallelogram flexible structure (2) and is used to adjust the parallelism between the end contact surfaces of the fingertips (2-3) of the two two-dimensional parallelogram flexible structures (2); The three-dimensional piezoelectric actuator (1) comprises: a stacked pre-tightening screw (1-1), a bridge-type amplification structure (1-2), a piezoelectric stack (1-3), and a bending drive module (1-4); The piezoelectric stack (1-3) is embedded in the bridge-type amplifying structure (1-2), and a stack pre-tightening screw (1-1) is used to provide a given pre-tightening force; The bottom of the bridge-type amplifying structure (1-2) is fixed on the structural support component (5), and the top of the bridge-type amplifying structure is fixedly connected to the bottom of the bending drive module (1-4); The bending drive module (1-4) comprises: a bottom end cover (1-4-1), a plurality of four-partition piezoelectric ceramics (1-4-2), a plurality of four-partition electrode sheets (1-4-3), a plurality of grounding electrode sheets (1-4-4), a top end cover (1-4-5), and a No. 2 pre-tightening screw (1-4-6); The bottom end cover (1-4-1), a plurality of four-partition piezoelectric ceramics (1-4-2), a plurality of four-partition electrode sheets (1-4-3), a plurality of ground electrode sheets (1-4-4), and a top end cover (1-4-5) are stacked in sequence from bottom to top along the Z-axis direction and fixed with No. 2 pre-tightening screws (1-4-6); the top of the top end cover (1-4-5) is fixedly connected to the input end of a two-dimensional parallelogram flexible structure (2); Every two partitions of the four-partition piezoelectric ceramic (1-4-2) are grouped together, with one group of partitions being arranged opposite to each other along the X-axis direction, and the other group of partitions being arranged opposite to each other along the Y-axis direction; The polarization directions of two partitions in the same group of partitions of the four-partition piezoelectric ceramic (1-4-2) are opposite.

2. A two-finger 5-DOF piezoelectric micro-gripper according to claim 1, characterized in that: The fingertip (2-3) comprises a connecting end (2-3-1) at the bottom end, a connecting column (2-3-2) at the bottom, a transverse beam (2-3-3) in the middle, a thin beam structure (2-3-4) at the top, and a clamping column (2-3-5) at the top end; the end of the clamping column (2-3-5) is a contact surface.

3. A two-finger 5-DOF piezoelectric micro-gripper according to claim 1, characterized in that: The plurality of parallelism adjustment piezoelectric sheets (3) are adhered to the surfaces of the fingertips (2-3) of the two-dimensional parallelogram flexible structure (2).

4. A two-finger 5-DOF piezoelectric micro-gripper according to claim 2, characterized in that: The clamp further comprises a strain gauge (4); The strain gauge (4) is attached to the thin beam structure (2-3-4) of the fingertip (2-3) and is used to measure the clamping force and provide feedback.

5. The dual-finger 5-DOF piezoelectric micro-gripper according to claim 1, characterized in that: The structural support component (5) comprises a packaging cover (5-1), an outer shell (5-2) and an inner shell (5-3); The inner shell (5-3) comprises a circular flat plate at the bottom and a cubic support column located in the center of the circular flat plate; Two three-dimensional piezoelectric actuators (1) are symmetrically fixed on the circular plate; Two two-dimensional parallelogram flexible structures (2) are symmetrically arranged on both sides of the cubic support column and are respectively fixedly connected to one side of the cubic support column; The bottom end surface of the housing (5-2) is fixedly arranged on a circular flat plate, and the top end surface thereof is fixedly connected to the packaging cover (5-1); One side plane inner wall of the shell (5-2) is located on one side of a two-dimensional parallelogram flexible structure (2), and the two are fixedly connected; The other side plane inner wall of the shell (5-2) is located on one side of another two-dimensional parallelogram flexible structure (2), and the two are fixedly connected.

6. A two-finger 5-DOF piezoelectric micro-gripper according to claim 1, characterized in that: The fixed end of the two-dimensional parallelogram flexible structure (2) is fixedly connected to the structural support component (5); The input end of the two-dimensional parallelogram flexible structure (2) is fixedly connected to the top of the three-dimensional piezoelectric actuator (1); The top end output end of the two-dimensional parallelogram flexible structure (2) is a fingertip (2-3); The two-dimensional parallelogram flexible structure (2) is used to guide the original output displacements generated by the three-dimensional piezoelectric actuator (1) along the X-axis direction, the Y-axis direction, and the Z-axis direction by utilizing the characteristics of the parallelogram being unstable and easily deformed and the opposite sides always remaining parallel; it is also used to amplify the original output displacements generated by the three-dimensional piezoelectric actuator (1) along the X-axis direction and the Y-axis direction by utilizing the lever principle; and it is also used to achieve decoupling of the final output displacements along the X-axis direction, the Y-axis direction, and the Z-axis direction by utilizing the characteristic that the longitudinal stiffness of the flexible hinge is much greater than the lateral stiffness.

7. The two-finger 5-DOF piezoelectric micro-gripper according to claim 1, characterized in that: Each two-dimensional parallelogram flexible structure (2) is composed of an input end, four parallel pillars (2-1), a flexible hinge (2-2) and a fingertip (2-3); The bottom of each column (2-1) is connected to the input end via a flexible hinge (2-2) arranged along the Z-axis; The fixed end of the side surface of the bottom of each column (2-1) is connected to the structural support component (5) through a flexible hinge (2-2) arranged along the X-axis direction; The top of each pillar (2-1) is connected to the fingertip (2-3) via a flexible hinge (2-2) arranged along the Z-axis.

8. A driving method for a two-finger 5-DOF piezoelectric micro-gripper, characterized in that: The driving method is used to drive a two-finger 5-DOF piezoelectric micro-gripper as claimed in any one of claims 1 to 7, so as to realize the clamping and opening actions of the contact surfaces at the end of the two fingertips (2-3), and to operate the micro-object to move along the X-axis, Y-axis and Z-axis, rotate around the Z-axis and deflect around the Y-axis; The driving method shown includes the following steps: Step 1: Exciting the original output displacements of the two three-dimensional piezoelectric actuators (1) along the X-axis direction in opposite directions and driving them closer to each other, so that the contact surfaces at the ends of the two fingertips (2-3) are opened, so as to place the micro-object between the two contact surfaces, or to release the clamped micro-object; Step 2: Exciting the original output displacements of the two three-dimensional piezoelectric actuators (1) along the X-axis to drive them in opposite directions and away from each other, so that the contact surfaces of the two fingertips (2-3) are closed to clamp the micro-object; Step 3: The original output displacements of the two three-dimensional piezoelectric actuators (1) along the X-axis are driven in the same direction, so that the contact surfaces of the two fingertips (2-3) move in the same direction along the X-axis, and the moving direction is opposite to the direction of the original output displacement along the X-axis, so as to manipulate the micro-object to move along the X-axis; Step 4: The original output displacements of the two three-dimensional piezoelectric actuators (1) along the Y-axis are driven in the same direction, so that the contact surfaces of the two fingertips (2-3) move in the same direction along the Y-axis, and the moving direction is opposite to the direction of the original output displacement along the Y-axis, so as to manipulate the micro-object to move along the Y-axis; Step 5: The original output displacements of the two three-dimensional piezoelectric actuators (1) along the Z axis are driven in the same direction, so that the contact surfaces of the two fingertips (2-3) move in the same direction along the Z axis, and the moving direction is the same as the direction of the original output displacement along the Z axis, so as to manipulate the micro-object to move along the Z axis; Step 6: The original output displacements of the two three-dimensional piezoelectric actuators (1) along the Y-axis are driven in opposite directions, so that the contact surfaces of the two fingertips (2-3) move in opposite directions along the Y-axis, respectively, to twist the micro-object and rotate it around the Z-axis. Step 7: Stimulate the original output displacements of the two three-dimensional piezoelectric actuators (1) along the X-axis direction in opposite directions and drive them away from each other, and at the same time stimulate only the original output displacement of any one of the three-dimensional piezoelectric actuators (1) along the Z-axis direction, so that the contact surfaces of the two fingertips (2-3) are closed and displaced along the Z-axis direction, so as to twist the micro-object and deflect it around the Y-axis direction.

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