Dual-piezoelectric-driven high-magnification-ratio variable-clamping-force micro-nano clamping device

Abstract

The invention relates to a double-piezoelectric-driven high-magnification-ratio variable-clamping-force micro-nano clamping device which is characterized in that a magnification frame of a magnification base comprises a fixed base, a connecting hinge part and a supporting part, and two magnification lever arms are arranged on the two sides of the magnification frame respectively; the stress end of the inner side of the horizontal arm of the amplification lever arm is connected with the corresponding end of the supporting part and the corresponding end of the fixed base through the connecting hinge parts on the corresponding sides, the lower ends of the clamping arms on the two sides of the clamping unit are connected with the upper ends of the vertical arms on the corresponding sides, and the two piezoelectric ceramic units are arranged in the piezoelectric frame side by side; lever hinge parts are arranged on the vertical arms of the amplification lever arms, and the lower ends of the connecting parts on the two sides of the piezoelectric frame are hinged to the lever hinge parts on the corresponding sides respectively. According to the piezoelectric actuator, large displacement output from micron-sized displacement of the piezoelectric ceramic units to the tail ends of the clamping arms can be effectively achieved, the capacitive load of the piezoelectric actuator can be remarkably reduced, the bandwidth and dynamic response performance of the driving circuit are effectively improved, and meanwhile the clamping arms can be flexibly replaced.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano manipulation, and more specifically to a micro-nano clamping device with a high amplification ratio and variable clamping force driven by bimorph piezoelectricity. Background Art

[0002] Micro-nano manipulation technology has crucial applications in high-end precision fields such as microelectronics manufacturing, biomedical engineering, and nanomaterial assembly. With the continuous reduction of the feature size of integrated circuits, the increasing requirements for the micro-scale dynamic manipulation of cells or biological tissues in biomedicine, and the continuous improvement of the manufacturing and manipulation accuracy of nanomaterials, more stringent technical requirements have been put forward for micro-nano manipulation devices in the scientific research and industrial fields.

[0003] In the prior art, the piezoelectric ceramic driving method has become the most commonly used driving method for micro-nano grippers due to its advantages such as fast response, high displacement accuracy, high stiffness, and strong driving force. However, this method has the following disadvantages:

[0004] First, for the micro-nano grippers in the prior art, their displacement amplification structures generally adopt single-stage flexible mechanisms or single-lever amplification mechanisms, and the overall amplification factor is relatively low (usually not exceeding 5 times). In micro-nano scale operations, the output displacement of piezoelectric ceramics is generally only in the micron or even sub-micron level, and the displacement is not sufficient to achieve effective clamping and manipulation. Therefore, in order to obtain a larger displacement output, traditional solutions usually need to use piezoelectric ceramics with larger sizes, higher voltages, or multiple piezoelectric ceramics connected in series. This not only increases the capacitive load, reduces the dynamic response speed, but also increases the overall complexity and size of the device, making it difficult for the device to meet the requirements of miniaturization and integration.

[0005] Second, the piezoelectric ceramic as a driving unit has a capacitive load effect, which has become an important bottleneck severely restricting the improvement of the high dynamic performance of the micro-nano manipulation system. When the capacitance value of the piezoelectric ceramic is large (such as exceeding 1 μF or even higher), the capacitive load driven by the high-voltage amplifier circuit increases sharply, and the capacitive reactance decreases rapidly with the increase of frequency, resulting in a sharp increase in the instantaneous current output by the high-voltage driving circuit, obvious thermal effects and power losses, and then significantly reducing the dynamic response bandwidth and stability of the system, and it is difficult to meet the requirements of rapid and precise clamping and dynamic response. For example, in microelectronic assembly, the gripper needs to quickly grasp and release tiny electronic components at a high frequency of dozens of kilohertz. Another example is in the field of biomedicine, where it is necessary to dynamically adjust the clamping force in real time for the capture, release, and precise mechanical measurement of cell or tissue samples. Currently, in these high-frequency manipulation scenarios, the sharp decrease in the capacitive reactance caused by the capacitive load of the piezoelectric ceramic leads to a huge demand for the instantaneous current of the amplifier, resulting in a lag in the output voltage response, serious signal distortion, a decrease in the amplifier efficiency, and even possible damage to the equipment due to excessive heat loss of the amplifier. Existing technologies usually compromise by increasing the amplifier power, selecting more expensive high-current driving chips, or reducing the operating frequency, which will increase the equipment cost and make it difficult for the manipulation performance to meet the actual application requirements.

[0006] Third, most micro-nano grippers in the existing technologies are designed for a single specific application scenario, such as a rigid gripper designed specifically for high clamping force or a low-stiffness gripper designed only for flexible clamping. The single-function design makes the existing grippers unable to quickly and flexibly adapt to multiple application scenarios. For example, grippers with large clamping force generally have a high stiffness and are difficult to achieve precise small clamping force control; while precise small clamping force grippers generally adopt a low-stiffness structure, are difficult to achieve a large clamping force, and lack real-time force feedback control. This single nature leads to the need to re-design and process the structure for different objects to be clamped in actual engineering applications, which is costly and inefficient, and severely restricts the versatility of the gripper and the convenience of engineering applications.

[0007] Therefore, in summary, there is an urgent need to develop a new type of micro-nano gripper with a simple and compact structure, high amplification ratio, which can effectively reduce the load of the piezoelectric driver, significantly improve the manipulation bandwidth, and have a flexible variable clamping force, so as to break through the above bottlenecks and meet the comprehensive performance requirements of micro-nano manipulation devices in high-end application fields such as microelectronic manufacturing, biomedical experiments, and nanotechnology. Summary of the Invention

[0008] The object of the present invention is to provide a dual piezoelectric-driven high magnification variable clamping force micro-nano clamping device, which can effectively achieve large displacement output from the micron-level displacement of the piezoelectric ceramic unit to the end of the clamping arm, and can significantly reduce the capacitive load of the piezoelectric driver, effectively improving the bandwidth and dynamic response performance of the drive circuit. At the same time, the clamping arm can be flexibly replaced according to actual needs.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] A dual piezoelectric-driven high magnification variable clamping force micro-nano clamping device, comprising a clamping unit, a piezoelectric ceramic unit and an amplification base. The amplification base includes a piezoelectric frame, an amplification frame and an amplification lever arm. The amplification frame includes a fixed base, a connecting hinge part and a supporting part. Two amplification lever arms are respectively arranged on both sides of the amplification frame, and the amplification lever arm includes a horizontal arm and a vertical arm arranged in an L shape. One side of the stress end inside the horizontal arm is connected to the corresponding end of the supporting part through the connecting hinge part on the corresponding side, and the other side is connected to the corresponding end of the fixed base through the connecting hinge part on the corresponding side. The clamping unit includes clamping arms on both sides, and the lower end of the clamping arm is connected to the upper end of the vertical arm on the corresponding side. The piezoelectric frame is concave and includes connecting parts on both sides and a limiting part in the middle. Two piezoelectric ceramic units are arranged in parallel in the piezoelectric frame and are arranged between the limiting part and the supporting part of the amplification frame. A lever hinge part is provided on the vertical arm, and the lower ends of the connecting parts on both sides of the piezoelectric frame are respectively hinged to the lever hinge parts on the corresponding sides.

[0011] The stress end inside the horizontal arm and the connecting hinge parts on both sides form a triangular structure. A plurality of circular notches are provided on the connecting hinge parts, and hinge parts that generate elastic deformation are formed at the circular notches.

[0012] A connecting block is provided at the upper end of the vertical arm of the amplification lever arm, and the connecting block is fixedly connected to the lower end of the corresponding clamping arm through a fixing screw.

[0013] Base fixing holes are provided on the fixed base of the amplification frame.

[0014] Threaded holes for fixing the piezoelectric ceramic unit are provided on the limiting part of the piezoelectric frame.

[0015] The piezoelectric ceramic unit includes a piezoelectric housing, and piezoelectric ceramic sheets and electrode layers are alternately arranged along the length direction inside the piezoelectric housing. A positive electrode lead and a negative electrode lead are provided at the upper end of the piezoelectric housing and are connected to a piezoelectric driver. In addition, an insulating top cover is provided at the upper end of the piezoelectric housing and is in contact with the limiting part of the piezoelectric frame, and an insulating bottom cover is provided at the lower end and is in contact with the supporting part of the amplification frame.

[0016] The piezoelectric actuator includes an input protection circuit module, a low-voltage amplification circuit module, a high-voltage amplification circuit module, an output protection circuit module, and a capacitive load matching circuit module connected in series in sequence. The low-voltage amplification circuit module is connected to a low-voltage power supply. One side of the high-voltage amplification circuit module is connected to a high-voltage power supply, and the other side is connected to a phase compensation circuit module.

[0017] A connection hole is provided at the end of the clamping arm of the clamping unit and is fixedly connected to the upper end of the vertical arm of the corresponding side amplification lever arm. The clamping unit includes two types of clamping arms that can be used interchangeably. One is a high-rigidity clamping arm, and the other is a low-rigidity strain-sensing clamping arm.

[0018] The high-rigidity clamping arm includes a clamping arm section and a connecting arm section connected in sequence. The clamping arm section is inclined, and a connection hole is provided at the free end of the connecting arm section.

[0019] The low-rigidity strain-sensing clamping arm includes a first arm section, a second arm section, a third arm section, and a fourth arm section connected in sequence. The first arm section is inclined, the second arm section and the fourth arm section are parallel, and both ends of the third arm section are respectively connected to the lower end of the second arm section and the lower end of the fourth arm section correspondingly. The second arm section, the third arm section, and the fourth arm section enclose a strain sensor installation groove, and a connection hole is provided at the upper end of the fourth arm section.

[0020] The advantages and positive effects of the present invention are as follows:

[0021] 1. The present invention adopts a two-stage displacement amplification structure formed by an amplification frame and an amplification lever arm, which can effectively realize the large-displacement output from the micron-level displacement of the piezoelectric ceramic unit to the end of the clamping arm. The total amplification multiple can reach more than 12 times, and the structure is compact, efficient, and reliable.

[0022] 2. The present invention replaces the traditional single large-capacitance piezoelectric ceramic unit with two independent piezoelectric ceramic units, which can significantly reduce the capacitive load of a single-channel actuator and effectively improve the bandwidth and dynamic response performance of the drive circuit, especially suitable for high-dynamic micro-nano manipulation scenarios.

[0023] 3. The clamping unit of the present invention is designed with a structure that can quickly replace the clamping arm. Different types of clamping arms with different rigidities and functions can be flexibly selected according to different application requirements. The clamping force range covers from the millinewton level to 10 newtons, which can meet the clamping requirements of different scenarios and improve the application range and flexibility of the microgripper.

[0024] 4. In the low-rigidity strain-sensing clamping arm of the present invention, the second arm section, the third arm section, and the fourth arm section enclose a strain sensor installation groove to install a strain sensor to realize the real-time detection and feedback of the clamping force. The measurement accuracy can reach 1 mN, which is especially suitable for high-precision real-time manipulation requirements. Description of the Drawings

[0025] Figure 1 is the structural schematic diagram of the present invention,

[0026] Figure 2 is Figure 1 the structural schematic diagram of the enlarged base in

[0027] Figure 3 is Figure 1 the structural schematic diagram of the high-rigidity clamping arm adopted in the embodiment,

[0028] Figure 4 is the structural schematic diagram of the low-rigidity strain-sensing clamping arm adopted in another embodiment of the present invention,

[0029] Figure 5 is Figure 1 the structural schematic diagram of the piezoelectric ceramic unit in

[0030] Figure 6 is Figure 5 the schematic diagram of the state where the piezoelectric ceramic sheets and the electrode layers are alternately stacked inside the piezoelectric housing in

[0031] Figure 7 is the schematic diagram of the working state of the amplification frame in the enlarged base of the present invention,

[0032] Figure 8 is the schematic diagram of the working state of the amplification lever arm in the enlarged base of the present invention,

[0033] Figure 9 is the schematic diagram of the overall working state of the enlarged base of the present invention,

[0034] Figure 10 is the structural schematic diagram of the piezoelectric actuator cooperating with the piezoelectric ceramic unit of the present invention,

[0035] Figure 11 is Figure 10 the frequency response curve of the piezoelectric actuator driving a 0.7 μF piezoelectric ceramic in

[0036] Figure 12 is Figure 10 the frequency response curve of the piezoelectric actuator driving a 1.4 μF piezoelectric ceramic in

[0037] Among them, 1 is a clamping unit, 101 is a connecting arm segment, 102 is a clamping arm segment, 103 is a connecting hole, 104 is a first arm segment, 105 is a second arm segment, 106 is a strain sensor mounting groove, 107 is a third arm segment, 108 is a fourth arm segment, 2 is a piezoelectric ceramic unit, 201 is a piezoelectric housing, 202 is an insulating top cover, 203 is an insulating bottom cover, 204 is a positive electrode lead, 205 is a negative electrode lead, 206 is a piezoelectric ceramic sheet, 207 is an electrode layer, 3 is an amplification base, 301 is an amplification lever arm, 3011 is a connecting block, 3012 is a lever hinge part, 3013 is a hinge shaft, 3014 is a force-receiving end, 3015 is a force-applying end, 302 is a piezoelectric frame, 3021 is a limiting part, 3022 is a connecting part, 3023 is a threaded hole, 303 is an amplification frame, 3031 is a connecting hinge part, 3032 is a fixed base, 3033 is a support part, 3034 is a base fixing hole, 4 is a fixing screw, 5 is a piezoelectric actuator, 501 is an input protection circuit module, 502 is a low-voltage amplification circuit module, 503 is a high-voltage amplification circuit module, 504 is an output protection circuit module, 505 is a capacitive load matching circuit module, 506 is a low-voltage power supply, 507 is a high-voltage power supply, 508 is a phase compensation circuit module. Specific embodiments

[0038] The present invention will be further described in detail below with reference to the accompanying drawings.

[0039] As Figures 1 to 12 shown, the present invention includes a clamping unit 1, a piezoelectric ceramic unit 2, and an amplification base 3. The amplification base 3 includes a piezoelectric frame 302, an amplification frame 303, and an amplification lever arm 301. The amplification frame 303 includes a fixed base 3032, a connecting hinge part 3031, and a support part 3033. Two amplification lever arms 301 are respectively arranged on both sides of the amplification frame 303, and the amplification lever arm 301 includes a horizontal arm and a vertical arm arranged in an L shape. The force-receiving end 3014 on the inner side of the horizontal arm is connected to the corresponding end of the support part 3033 through the connecting hinge part 3031 on the corresponding side on one side and is connected to the corresponding end of the fixed base 3032 through the connecting hinge part 3031 on the corresponding side on the other side. The clamping unit 1 includes clamping arms on both sides, and the lower ends of the clamping arms are connected to the upper ends of the corresponding vertical arms. The piezoelectric frame 302 is concave, and it includes connecting parts 3022 on both sides and a limiting part 3021 in the middle. Two piezoelectric ceramic units 2 are arranged in parallel in the piezoelectric frame 302 and are arranged between the limiting part 3021 and the support part 3033 of the amplification frame 303. A lever hinge part 3012 is provided on the vertical arm, and the lower ends of the connecting parts 3022 on both sides of the piezoelectric frame 302 are respectively hinged to the free ends of the corresponding lever hinge parts 3012 through hinge shafts 3013. When the present invention works, as Figures 7 to 9As shown, when the piezoelectric ceramic unit 2 generates a driving displacement in the Z direction of Δx, a first-stage amplification can be formed through the amplification frame 303. At this time, the force-receiving end 3014 on the inner side of the horizontal arm of the amplification lever arm 301 is displaced in the X direction by Δx 1 , and the force-applying end 3015 on the outer side of the horizontal arm connected to the vertical arm is also displaced in the X direction by Δx 1 , and the force-applying end 3015 on the outer side of the horizontal arm drives the vertical arm and the clamping arm of the clamping unit 1 to rotate around the center of the hinge shaft 3013, and makes the end of the clamping arm displaced in the X direction to reach Δy, thereby forming a second-stage amplification. Through simulation and experimental measurement, for the micron-level initial displacement (Δx) at the output end of the piezoelectric ceramic unit 2, after the first-stage amplification by the amplification frame 303, a displacement (Δx 1 ) can be amplified by 5 to 6 times. After the second-stage amplification by the amplification lever arm 301, a displacement (Δy) can be further amplified by 2 to 3 times. Finally, the amplification multiple of the displacement (Δy) at the end of the clamping arm can be more than 12 times, which can effectively meet the requirements of large-displacement precision clamping in the micro-nano manipulation scenario. At the same time, the designed structure of the present invention is simple and compact, with high amplification efficiency, stable and reliable, and greatly improves the ability of the gripper to meet the requirements of high precision, large displacement and high dynamic response.

[0040] In this embodiment, the connecting hinge portion 3031 of the amplification frame 303 and the lever hinge portion 3012 of the amplification lever arm 301 both adopt a flexible circular hinge structure, which is a well-known technology in the art. For example, reference can be made to patents such as CN205521129U. Among them, as Figures 1 to 2 and Figure 7 shown, the force-receiving end 3014 on the inner side of the horizontal arm forms a triangular structure with the connecting hinge portions 3031 on both sides. The tiny displacement Δx generated by the piezoelectric ceramic unit 2 along the Z direction is applied to the support portion 3033, thereby causing elastic deformation of each connecting hinge portion 3031. The circular notch on the connecting hinge portion 3031 is the elastic deformation part, that is, the hinge. And after the connecting hinge portion 3031 is stressed, tiny rotations will occur at each hinge (circular notch) of it, and after the tiny rotations are superimposed, a significantly amplified displacement output Δx can be generated at the force-receiving end 3014 on the inner side of the horizontal arm 1 , and this amplification effect is directly related to the geometric dimensions of the triangular structure formed by the force-receiving end 3014 and the connecting hinge portions 3031 on both sides and the stiffness of the connecting hinge portion 3031. And the present invention can achieve precise control of displacement amplification by reasonably designing the distance between the support portion 3033 and the fixed base 3032, the radius of the arc at each hinge of the connecting hinge portion 3031, and the side length and included angle of the triangular structure formed by the force-receiving end 3014 and the connecting hinge portions 3031 on both sides.

[0041] And asFigure 8 As shown, the magnifying lever arm 301 uses the lever hinge portion 3012 as a hinge fulcrum to play a role in supporting and rotational deformation, thereby realizing the transmission and conversion of force and displacement. Among them, the horizontal arm force application end 3015 of the magnifying lever arm 301 applies a thrust to the vertical arm, and the small-amplitude movement generated by the horizontal arm force application end 3015 can, through the mechanical amplification effect of the lever arm length, realize a larger-amplitude displacement output (△y) at the end of the clamping arm of the clamping unit.

[0042] As Figures 1 to 2 shown, in this embodiment, a connecting block 3011 is provided at the upper end of the vertical arm of the magnifying lever arm 301, and the connecting block 3011 is fixedly connected to the lower end of the corresponding side clamping arm through a fixing screw 4.

[0043] As Figures 1 to 2 shown, in this embodiment, a base fixing hole 3034 is provided on the fixed base 3032 of the magnifying frame 303 for fixing to relevant structures.

[0044] As Figures 1 to 2 shown, in this embodiment, a threaded hole 3023 for fixing the piezoelectric ceramic unit 2 is provided on the limiting portion 3021 of the piezoelectric frame 302.

[0045] In this embodiment, the magnifying frame 303 and the magnifying lever arm 301 are processed from aluminum alloy 7075-T6 or titanium alloy Ti-6Al-4V materials, with high elastic deformation accuracy and long fatigue life. In addition, due to the large displacement magnification of the present invention, the overall structure is more compact. In this embodiment, the overall external dimension of the magnifying base 3 is 45mm×45mm, and it can realize high-efficiency displacement magnification and high-bandwidth piezoelectric drive in a compact space.

[0046] As Figures 5 to 6 shown, in this embodiment, the piezoelectric ceramic unit 2 includes a piezoelectric housing 201, and piezoelectric ceramic sheets 206 and electrode layers 207 are alternately arranged along the length direction inside the piezoelectric housing 201. The piezoelectric ceramic sheets 206 and the electrode layers 207 are alternately stacked and sintered, and they realize micron-level longitudinal expansion and contraction displacement by applying an external high-voltage signal. A positive electrode lead 204 and a negative electrode lead 205 are provided at the upper end of the piezoelectric housing 201 and are connected to the piezoelectric driver 5 to apply a high-voltage signal to the piezoelectric ceramic sheets 206 and the electrode layers 207. In addition, an insulating top cover 202 is provided at the upper end of the piezoelectric housing 201 to contact the limiting portion 3021 of the piezoelectric frame 302, and an insulating bottom cover 203 is provided at the lower end to contact the supporting portion 3033 of the magnifying frame 303. The materials of the piezoelectric ceramic sheets 206 and the electrode layers 207 are all well-known technologies in the art.

[0047] As Figure 10As shown, in this embodiment, the positive electrode lead 204 and the negative electrode lead 205 are connected to the piezoelectric driver 5. The piezoelectric driver 5 includes an input protection circuit module 501, a low-voltage amplification circuit module 502, a high-voltage amplification circuit module 503, an output protection circuit module 504, and a capacitive load matching circuit module 505 connected in series in sequence. Among them, the low-voltage amplification circuit module 502 is connected to the low-voltage power supply 506, one side of the high-voltage amplification circuit module 503 is connected to the high-voltage power supply 507, and the other side is connected to the phase compensation circuit module 508. The working principle of the piezoelectric driver 5 is as follows: First, the low-voltage control signal (±10V) input from the outside enters the low-voltage amplification circuit module 502 after passing through the input protection circuit module 501, and linearly converts the bipolar control signal of ±10V into a unipolar 0 to -10V signal suitable for subsequent high-voltage amplification. Subsequently, the 0 to -10V signal passes through the high-voltage amplification circuit module 503, and uses the high-voltage DC bias provided by the high-voltage power supply 507 to achieve a large-scale amplification of the voltage, amplifying the 0 to -10V low-voltage signal to the 0 to 150V high-voltage signal required to drive the piezoelectric ceramic unit 2, forming a drive output signal, and finally transmitting it to the piezoelectric ceramic unit 2. During the high-voltage amplification process, since the piezoelectric ceramic essentially belongs to a capacitive load, the larger the load capacitance value, the faster the capacitive reactance drops when the frequency of the amplifier output signal increases, and the current flowing into the load increases significantly, resulting in increased heating of the amplification circuit and serious phase lag, thereby limiting the bandwidth of the driver. To solve the above problems, a phase compensation circuit module 508 and a capacitive load matching circuit module 505 are adopted in the present invention to effectively improve the phase characteristics of the amplifier, improve the overall bandwidth and stability, and ensure that the driver can efficiently and stably achieve high-bandwidth driving of the piezoelectric ceramic.

[0048] In an application example of the present invention, the above piezoelectric driver 5 is used to drive two piezoelectric ceramic units 2 with a single capacitance value of 0.7 μF respectively, and the frequency response curve (Bode plot) of the single 0.7 μF piezoelectric ceramic unit 2 at this time is as Figure 10 shown. The ordinate in the figure represents the gain ratio (in dB) and phase (degrees) of the amplifier output signal and the input signal, and the abscissa represents the frequency (Hz). From Figure 10It can be seen that within the frequency band of 1 kHz to 10 kHz, the gain of this application example is stable at about 20 dB, indicating that the piezoelectric actuator 5 has good driving stability and gain flatness for capacitive loads, and can reliably achieve high-voltage precise driving. After the frequency is higher than 10 kHz, the amplifier gain curve begins to gradually decrease and significantly attenuates near 100 kHz, indicating that the system bandwidth can reach the order of dozens of kHz, fully meeting the performance requirements of the micro-nano gripper of the present invention under high-frequency dynamic operation conditions. Compared with the traditional single-channel piezoelectric driving scheme with a large capacitance (such as 1.4 μF and above), the scheme of using two low-capacitance (0.7 μF per piece) piezoelectric ceramic units 2 and driving them independently in the present invention can effectively halve the capacitive load of the single-channel driving amplifier, greatly reducing the design difficulty of the driving circuit, enabling the amplifier to obtain higher bandwidth and better dynamic performance, being particularly suitable for high-speed and precise clamping operations at the micro-nano scale, and significantly improving the adaptability of the gripper to different application scenarios.

[0049] And as Figure 11 shown is the comparative example of the above application example. This comparative example is the frequency response curve (Bode plot) when the above piezoelectric actuator 5 only drives a piezoelectric ceramic with a capacitance value of 1.4 μF. In the figure, the abscissa represents the input signal frequency, and the ordinate represents the output gain (unit: dB) and phase (unit: °) of the actuator respectively. It can be seen from this frequency response curve that when the capacitive load of the piezoelectric ceramic increases to 1.4 μF, the gain and phase performance of this comparative example significantly decline. Specifically, the amplifier can maintain a stable gain of about 20 dB before 1 kHz. However, when the frequency exceeds 1 kHz, the gain of the amplifier rapidly decreases. At a frequency of 10 kHz, the gain has dropped to about 13 dB, and at higher frequencies (above about 30 kHz), the gain even drops below 10 dB, indicating that the bandwidth is severely limited. Compared with the case of independently driving two 0.7 μF piezoelectric ceramics (see Figure 10 ), the high capacitive load of a single 1.4 μF piezoelectric ceramic brings higher output current requirements to the actuator, resulting in increased thermal loss and reduced frequency response of the driving circuit, limiting the high-frequency dynamic response ability. By comparing the frequency response characteristics of a single large-capacitance ceramic with two independent small-capacitance ceramics, the present invention clearly verifies that the dual-channel independent driving method can significantly improve the frequency bandwidth of the amplifier and the dynamic response performance of the system, and is particularly suitable for the micro-nano manipulation field with higher requirements for clamping speed, bandwidth, and stability. Therefore, the present invention uses two independent small-capacitance (0.7 μF) piezoelectric ceramic units to drive respectively instead of a conventional single large-capacitance (1.4 μF) piezoelectric ceramic unit to drive alone, which produces unexpected technical effects.

[0050] As Figures 3 to 4As shown in the figure, a connection hole 103 is provided at the end of the clamping arm of the clamping unit 1 of the present invention for fixedly connecting with the upper end of the vertical arm of the corresponding side amplification lever arm 301. The clamping unit 1 of the present invention includes two types of clamping arms that can be used interchangeably. One is a high-rigidity clamping arm, and the other is a low-rigidity strain-sensing clamping arm.

[0051] As Figure 3 shown in the figure, in this embodiment, the high-rigidity clamping arm includes a clamping arm section 102 and a connecting arm section 101 connected in sequence. The clamping arm section 102 is inclined, and a connection hole 103 is provided at the free end of the connecting arm section 101. The high-rigidity clamping arm can achieve a large clamping force of more than 10 N.

[0052] As Figure 4 shown in the figure, the low-rigidity strain-sensing clamping arm includes a first arm section 104, a second arm section 105, a third arm section 107, and a fourth arm section 108 connected in sequence. The first arm section 104 is inclined for clamping. The second arm section 105 and the fourth arm section 108 are parallel, and both ends of the third arm section 107 are vertically connected to the lower end of the second arm section 105 and the lower end of the fourth arm section 108 respectively. The second arm section 105, the third arm section 107, and the fourth arm section 108 enclose a strain sensor installation groove 106 to install a strain sensor to realize real-time detection and feedback of the clamping force. The clamping force measurement accuracy can reach 1 mN, and a connection hole 103 is provided at the upper end of the fourth arm section 108. The thickness of each arm section of the low-rigidity strain-sensing clamping arm is reduced and the cantilever length is increased. According to Hooke's law, it will generate a relatively small clamping force on the object.

[0053] The working principle of the present invention is:

[0054] When the present invention works, as Figures 7 to 9 shown in the figure, when the piezoelectric ceramic unit 2 generates a driving displacement of Δx in the Z direction, a first-level amplification can be formed through the amplification frame 303. At this time, the force-receiving end 3014 on the inner side of the horizontal arm of the amplification lever arm 301 is displaced by Δx in the X direction 1 , and the force-applying end 3015 connected to the vertical arm on the outer side of the horizontal arm is also displaced by Δx in the X direction 1 , and the force-applying end 3015 on the outer side of the horizontal arm drives the vertical arm and the clamping arm of the clamping unit 1 to rotate around the center of the hinge shaft 3013, and the end of the clamping arm is displaced by Δy in the X direction, thereby forming a second-level amplification. Through simulation and experimental calculation, the present invention can finally achieve an amplification multiple of more than 12 times the displacement (Δy) at the end of the clamping arm, which can effectively meet the requirements of large-displacement precision clamping in the micro-nano manipulation scenario. At the same time, the design structure of the present invention is simple and compact, with high amplification efficiency, stable and reliable, and greatly improves the ability of the gripper to meet the requirements of high precision, large displacement, and high dynamic response.

[0055] AsFigures 1 to 2 and Figures 10 to 11 As shown, the present invention uses two independent piezoelectric ceramic units with small capacitance values (0.7 μF) to drive respectively instead of using a conventional single piezoelectric ceramic unit with a large capacitance value (1.4 μF) to drive alone. It can significantly improve the frequency bandwidth of the present invention and the dynamic response performance of the system, and is especially suitable for the micro-nano manipulation field with higher requirements for clamping speed, bandwidth and stability. At the same time, a phase compensation circuit module 508 and a capacitive load matching circuit module 505 are adopted in the piezoelectric actuator 5 of the present invention to effectively improve the phase characteristics of the amplifier, enhance the overall bandwidth and stability, and ensure that the actuator can efficiently and stably achieve high-bandwidth driving of the piezoelectric ceramic.

[0056] As Figures 1 to 4 shown, a connection hole 103 is provided at the end of the clamping arm of the clamping unit 1 of the present invention for the fixing screw 4 to pass through, so as to realize the fixed connection with the connection block 3011 at the upper end of the vertical arm of the corresponding side amplification lever arm 301. The clamping unit 1 of the present invention includes two types of clamping arms that can be used interchangeably. One is a high-rigidity clamping arm, and the other is a low-rigidity strain-sensing clamping arm. The present invention can flexibly select a suitable clamping arm according to the situation of the clamped object, so as to meet the requirements of different clamping scenarios. Moreover, the amplification frame 303 and the amplification lever arm 301 of the present invention can finally form an amplification multiple of more than 12 times the displacement (Δy) at the end of the clamping arm, without affecting the conversion and use of the above clamping arm structure.

Claims

1. A dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device, characterized in that: The invention comprises a clamping unit (1), a piezoelectric ceramic unit (2) and an amplifying base (3), wherein the amplifying base (3) comprises a piezoelectric frame (302), an amplifying frame (303) and an amplifying lever arm (301), wherein the amplifying frame (303) comprises a fixed base (3032), a connecting hinge portion (3031) and a supporting portion (3033), two amplifying lever arms (301) are arranged on both sides of the amplifying frame (303), and the amplifying lever arm (301) comprises a horizontal arm and a vertical arm arranged in an L shape, wherein one side of the force-bearing end (3014) on the inner side of the horizontal arm is connected to the corresponding end of the supporting portion (3033) through the connecting hinge portion (3031) on the corresponding side, and the other side is connected to the corresponding end of the supporting portion (3033) through the connecting hinge portion (3031) on the corresponding side. The hinge part (3031) is connected to the corresponding end of the fixed base (3032), the clamping unit (1) includes clamping arms on both sides, and the lower end of the clamping arm is connected to the upper end of the vertical arm on the corresponding side, the piezoelectric frame (302) is concave and includes connecting parts (3022) on both sides and a limiting part (3021) in the middle, two piezoelectric ceramic units (2) are arranged in parallel in the piezoelectric frame (302) and arranged between the limiting part (3021) and the supporting part (3033) of the amplifying frame (303), the vertical arm is provided with a lever hinge part (3012), and the lower ends of the connecting parts (3022) on both sides of the piezoelectric frame (302) are respectively hinged to the lever hinge part (3012) on the corresponding side.

2. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 1, characterized in that: The force-bearing end (3014) on the inner side of the horizontal arm and the connecting hinge parts (3031) on both sides form a triangular structure. The connecting hinge parts (3031) are provided with a plurality of circular notches, and the circular notches form hinges that generate elastic deformation.

3. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 1, characterized in that: A connecting block (3011) is provided at the upper end of the vertical arm of the amplifying lever arm (301), and the connecting block (3011) is fixedly connected to the lower end of the corresponding side clamping arm via a fixing screw (4).

4. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 1, characterized in that: A base fixing hole (3034) is provided on the fixing base (3032) of the amplifying frame (303).

5. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 1, characterized in that: The limiting portion (3021) of the piezoelectric frame (302) is provided with a threaded hole (3023) for fixing the piezoelectric ceramic unit (2).

6. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 1, characterized in that: The piezoelectric ceramic unit (2) comprises a piezoelectric shell (201), and piezoelectric ceramic sheets (206) and electrode layers (207) are arranged alternately along the length direction inside the piezoelectric shell (201); a positive electrode lead (204) and a negative electrode lead (205) are arranged at the upper end of the piezoelectric shell (201) and are connected to the piezoelectric driver (5); in addition, an insulating top cover (202) is arranged at the upper end of the piezoelectric shell (201) and is in contact with a limiting portion (3021) of the piezoelectric frame (302); and an insulating bottom cover (203) is arranged at the lower end and is in contact with a supporting portion (3033) of the amplifying frame (303).

7. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 6, characterized in that: The piezoelectric driver (5) comprises an input protection circuit module (501), a low-voltage amplifier circuit module (502), a high-voltage amplifier circuit module (503), an output protection circuit module (504) and a capacitive load matching circuit module (505) which are sequentially connected in series, wherein the low-voltage amplifier circuit module (502) is connected to a low-voltage power supply (506), and one side of the high-voltage amplifier circuit module (503) is connected to a high-voltage power supply (507) and the other side is connected to a phase compensation circuit module (508).

8. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 1, characterized in that: The end of the clamping arm of the clamping unit (1) is provided with a connection hole (103) fixedly connected to the upper end of the vertical arm of the corresponding side amplification lever arm (301), and the clamping unit (1) comprises two types of clamping arms that can be used interchangeably, one of which is a high-rigidity clamping arm and the other is a low-rigidity strain sensing clamping arm.

9. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 8, characterized in that: The high-rigidity clamping arm comprises a clamping arm section (102) and a connecting arm section (101) which are connected in sequence, wherein the clamping arm section (102) is arranged obliquely, and a connecting hole (103) is provided at the free end of the connecting arm section (101).

10. The dual piezoelectric driven high amplification ratio variable clamping force micro-nano clamping device according to claim 8, characterized in that: The low-rigidity strain sensor clamping arm comprises a first arm segment (104), a second arm segment (105), a third arm segment (107) and a fourth arm segment (108) which are connected in sequence, wherein the first arm segment (104) is arranged obliquely, the second arm segment (105) and the fourth arm segment (108) are arranged in parallel, and the two ends of the third arm segment (107) are respectively connected to the lower end of the second arm segment (105) and the lower end of the fourth arm segment (108), the second arm segment (105), the third arm segment (107) and the fourth arm segment (108) enclose a strain sensor installation groove (106), and the upper end of the fourth arm segment (108) is provided with a connection hole (103).

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