Ultrasonic actuator based on annular non-uniformly distributed electrodes and working method

Abstract

The ultrasonic actuator comprises a bearing plate, an onboard circuit is arranged in the upper space of the bearing plate, an annular piezoelectric ceramic plate and an annular vibrating body are sequentially arranged in the lower space of the bearing plate, and driving feet are arranged on the lower bottom face of the annular vibrating body. The surface of the annular piezoelectric ceramic plate is provided with a plurality of electrodes which are non-uniformly arranged, specifically, the circle center of the annular piezoelectric ceramic plate is taken as a reference, the annular piezoelectric ceramic plate is divided into eight equal parts and six equal parts along the annular direction, a corresponding electrode is arranged in each equal part area, and a set deviation angle is formed between the eight equal parts and the six equal parts. According to the annular piezoelectric actuator, the electromechanical coupling coefficient can be improved on the premise that the size and the mass of the actuator are not increased in a non-uniform electrode division mode, so that the actuator has large mechanical output performance; and meanwhile, an onboard circuit is used for controlling and driving the actuator, so that the actuator gets rid of the constraint of a high-power power supply and a cable.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric actuators, and specifically to an ultrasonic actuator based on annular non-uniformly distributed electrodes and a working method thereof. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention, and do not necessarily constitute prior art.

[0003] A piezoelectric actuator is an actuating element that utilizes the inverse piezoelectric effect to generate displacement by applying voltage. Compared with electromagnetic actuators or traditional motors, piezoelectric actuators have many advantages such as simple structure, no electromagnetic interference, and self-locking in the power-off state. In recent years, piezoelectric actuators have been widely used in high-precision, high-integration, and high-power-density scenarios such as optical focusing devices, micro-robots, and medical devices.

[0004] Generally, the working principles of piezoelectric actuators can be divided into four types: direct drive, stick-slip, inchworm, and resonance. Among them, the direct-drive piezoelectric actuator usually uses the direct extension of the piezoelectric stack to generate the output displacement, which can provide nanometer-level resolution but has a limited working stroke; the stick-slip piezoelectric actuator realizes an infinite motion range through the step motion of slow extension and fast retraction, but backward motion will occur during the sliding motion stage, thus greatly reducing the positioning accuracy and speed of the actuator; the inchworm piezoelectric actuator converts the small displacement of the piezoelectric material into a long-stroke displacement output through the peristaltic forward movement of stretching - contraction - stretching, with relatively high moving resolution, but has a cumbersome structure and complex control strategy.

[0005] In contrast, the resonant piezoelectric actuator uses the resonant mode of the substrate to drive the slider or rotor, and can be divided into traveling-wave piezoelectric actuators and standing-wave piezoelectric actuators. Among them, the standing-wave synthesis condition is simple, easy to realize the miniaturization of the structure, and the standing-wave piezoelectric actuator has advantages such as strong output force and adjustable driving signal, and has the potential to achieve high load-bearing and high positioning capabilities.

[0006] In order to meet the usage requirements in different scenarios, there are various standing-wave piezoelectric actuators in the existing technology.

[0007] For example, CN105141174 proposes a patch-type standing-wave rotary piezoelectric actuator, which has the advantages of simple structure, compactness, easy processing, assembly, and miniaturization, and solves the problem of frequency consistency.

[0008] For example, CN102185096 proposes a piezoelectric actuator and a linear piezoelectric motor. The piezoelectric actuator has a simple structure, is practical and convenient, can effectively reduce the driving voltage of the piezoelectric actuator, and improve the driving force.

[0009] In addition, the standing wave type hybrid excitation motor proposed in CN109361326 and CN114977879 and the bidirectional moving self-propelled traveling wave type linear ultrasonic wave can also achieve actuation purposes such as the piezoelectric / ultrasonic actuator body or load-carrying movement.

[0010] However, the structures of some existing actuators are irregular, resulting in high manufacturing complexity, high processing costs, and large assembly errors for their vibrating bodies, making it difficult to achieve the goal of miniaturizing the actuator. The ring-shaped actuator has a simple structure and can reduce the manufacturing complexity of the actuator. Most of the existing ring-shaped actuators evenly distribute piezoelectric ceramics to achieve the purpose of simple manufacturing and lightweight structure.

[0011] Secondly, the dispersed distribution of piezoelectric ceramics will reduce the matching degree between the excitation region and the vibration mode, making it difficult to achieve strong electromechanical coupling under each vibration mode, thus limiting the mechanical output of the actuator.

[0012] In addition, the overall structure of the existing piezoelectric actuator powered by an external power supply is large in volume and mass, resulting in limited applicable scenarios. Summary of the Invention

[0013] In order to solve the technical problems existing in the above background technology, the present invention provides an ultrasonic actuator and a working method based on a ring-shaped non-uniformly distributed electrode. A ring-shaped self-moving piezoelectric actuator is designed. By non-uniformly dividing the electrodes, the electromechanical coupling coefficient can be improved without increasing the volume and mass of the actuator, enabling the actuator to have large mechanical output performance. At the same time, an on-board circuit is used to control and drive the actuator, enabling the actuator to get rid of the constraints of high-power power supplies and cables and achieve high-speed / large-load / high-resolution / large-stroke performance output.

[0014] To achieve the above object, the present invention adopts the following technical solutions: The first aspect of the present invention provides an ultrasonic actuator based on a ring-shaped non-uniformly distributed electrode, including: a carrier plate, an on-board circuit is provided in the space above the carrier plate, a ring-shaped piezoelectric ceramic plate and a ring-shaped vibrating body are sequentially provided in the space below the carrier plate, and driving feet are provided on the lower bottom surface of the ring-shaped vibrating body; The surface of the ring-shaped piezoelectric ceramic plate has a plurality of non-uniformly arranged electrodes. Specifically: taking the center of the ring-shaped piezoelectric ceramic plate as a reference, it is divided into eight equal parts and six equal parts along the circumferential direction respectively, and corresponding electrodes are provided in each equal part region, and there is a set offset angle between the eight equal parts and the six equal parts.

[0015] As a further implementation method, the driving feet include front feet, middle feet, and rear feet. The front feet and the rear feet are 180°, and at least two middle feet are symmetrically distributed with respect to the line connecting the front feet and the center of the ring-shaped vibrating body, and the interval angle is a set value.

[0016] As a further implementation, the electrodes in the eight-equal division regions are excited at a set excitation voltage and frequency, causing the annular vibrating body to enter the circumferential fourth-order bending mode.

[0017] As a further implementation, in the fourth-order bending mode, the front feet and middle feet alternately push the ground under the excitation of the bending standing wave, generating a radially downward oblique driving force to drive the actuator to perform a straight-line motion.

[0018] As a further implementation, the electrodes in the six-equal division regions are excited at a set excitation voltage and frequency, causing the annular vibrating body to enter the circumferential third-order bending mode.

[0019] As a further implementation, in the third-order bending mode, the front feet and middle feet alternately push the ground under the excitation of the bending standing wave, generating a circumferentially downward oblique driving force to drive the actuator to perform a rotational motion.

[0020] As a further implementation, the moving speed of the actuator is adjusted by changing the amplitude of the excitation voltage.

[0021] As a further implementation, the on-board circuit includes a driving circuit, a control circuit, and an isolation circuit. The remote controller is electrically connected to the wireless communication module in the control circuit. The piezoelectric ceramic sheet is connected to the relay in the isolation circuit. The battery is respectively connected to the voltage regulator in the control circuit and the boost circuit in the driving circuit. A full-bridge driving circuit is provided in the driving circuit, an isolation transformer is provided in the isolation circuit, and a microcontroller is provided in the control circuit.

[0022] As a further implementation, the wireless communication module receives the remote control instructions sent by the remote controller, generates the input signal of the full-bridge driving circuit after being processed by the microcontroller, and the driving signal output by the full-bridge driving circuit is input into the relay through the isolation transformer. The motion mode switching signal output by the microcontroller controls the relay to output different excitation signals to realize the dynamic switching of the piezoelectric ceramic electrode excitation region.

[0023] The second aspect of the present invention provides a working method for an ultrasonic actuator based on annular non-uniformly distributed electrodes, including the following steps: The electrodes in the eight-equal division regions are excited at a set excitation voltage and frequency, causing the annular vibrating body to enter the circumferential fourth-order bending mode. The front feet and middle feet alternately push the ground under the excitation of the bending standing wave, generating a radially downward oblique driving force to drive the actuator to perform a straight-line motion; The electrodes in the six-equal division regions are excited at a set excitation voltage and frequency, causing the annular vibrating body to enter the circumferential third-order bending mode. The front feet and middle feet alternately push the ground under the excitation of the bending standing wave, generating a circumferentially downward oblique driving force to drive the actuator to perform a rotational motion.

[0024] Compared with the prior art, the above one or more technical solutions have the following beneficial effects: 1. Aiming at the problems that the irregular structure of the multi-degree-of-freedom actuator makes the manufacturing complexity of its vibrating body high, the processing cost high, the assembly error large, and it is difficult to miniaturize the actuator, it is proposed to change the linear vibration mode of the traditional rectangular structure actuator through the annular configuration of the piezoelectric actuator, realizing the multi-degree-of-freedom movement of the actuator; moreover, the mechanical part of the proposed actuator is only composed of a simple circular ring and a piezoelectric ceramic plate, reducing the complexity of the actuator structure assembly and realizing the miniaturization of the actuator.

[0025] 2. Aiming at the existing multi-degree-of-freedom actuator using an annular configuration, the dispersed configuration of its piezoelectric ceramics reduces the matching degree between the excitation area and the vibration mode, making it difficult to achieve strong electromechanical coupling under each vibration mode, resulting in unbalanced mechanical output under various motions of the actuator and limiting its high load-bearing capacity. A non-uniform electrode division method is proposed, dividing the complete circular ring into 14 non-uniform parts. On the one hand, according to the required motion mode of the actuator, the corresponding circular ring vibration mode can be excited, thereby realizing the three-degree-of-freedom movement of straight-line and rotation in the plane; on the other hand, the non-uniform division of the electrodes of the piezoelectric ceramic plate maximizes the matching degree between the excitation area of the annular piezoelectric ceramic plate and the vibration mode of the annular vibrating body under the two modes, and overall realizes a relatively high electromechanical coupling coefficient under the two vibration modes, improving the mechanical output performance of the actuator.

[0026] 3. Aiming at the problem that it is difficult for a piezoelectric actuator powered by an external power supply to achieve the design goals of light weight and miniaturization, and the movement of the actuator is limited by the power supply and the length of the cable. It is proposed to drive the actuator with an on-board circuit, reducing the volume of the drive system and realizing the miniaturization and integration of the system; the actuator is free from the constraints of the power supply and the power supply cable, has strong controllability, and greatly expands the applicable scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The schematic diagrams of the drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0028] Figure 1 is a schematic diagram of the overall structure of the actuator provided by one or more embodiments of the present invention; Figure 2 is a top view structure schematic diagram of the actuator provided by one or more embodiments of the present invention; Figure 3 is a vibration displacement distribution diagram of the actuator under two modes provided by one or more embodiments of the present invention; Figure 4 is a schematic diagram of the electrode division of the piezoelectric ceramic plate of the actuator provided by one or more embodiments of the present invention; Figure 5 Schematic diagram of the third-order bending mode of the actuator provided by one or more embodiments of the present invention; Figure 6 Schematic diagram of the fourth-order bending mode of the actuator provided by one or more embodiments of the present invention; Figure 7 Schematic diagram of the excitation of the six-equal-part electrodes of the piezoelectric ceramic plate of the actuator provided by one or more embodiments of the present invention; Figure 8 Schematic diagram of the excitation of the eight-equal-part electrodes of the piezoelectric ceramic plate of the actuator provided by one or more embodiments of the present invention; Figure 9 Schematic diagram of the on-board circuit of the actuator provided by one or more embodiments of the present invention; Figure 10 Schematic diagram of the driving and control process of the actuator provided by one or more embodiments of the present invention.

[0029] Figure 1 In the figure: 20 annular piezoelectric ceramic plate, 60 on-board circuit, 70 carrier plate; Figure 2 In the figure: 30 front foot, 40 middle foot, 50 rear foot; Figure 4 In the figure: 1 electrode a, 2 electrode b, 3 electrode c, 4 electrode d, 5 electrode e, 6 electrode f, 7 electrode g, 8 electrode h, 9 electrode i, 10 electrode j, 11 electrode k, 12 electrode l, 13 electrode m, 14 electrode n. Detailed implementation manners

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0032] It should be noted that the terms herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] The following embodiments provide an ultrasonic actuator based on a circular non-uniformly distributed electrode and a working method. Considering the irregular structure of existing actuators, which leads to high manufacturing complexity, high processing cost, large assembly error of their vibrating bodies, and difficulty in miniaturizing the actuator. And the problem that the overall structure of existing piezoelectric actuators powered by external power sources is large in volume and mass, resulting in limited applicable scenarios. A circular self-moving piezoelectric actuator is designed. By non-uniformly dividing the electrodes, the electromechanical coupling coefficient can be increased without increasing the volume and mass of the actuator, enabling the actuator to have large mechanical output performance; at the same time, using an on-board circuit to control and drive the actuator can free the actuator from the constraints of high-power power sources and cables, achieving high-speed / large-load / high-resolution / large-stroke performance output of the actuator.

[0034] Embodiment 1: Considering the defects existing in existing actuators comprehensively, as follows: Defect 1: The irregular structure of the multi-degree-of-freedom actuator makes the manufacturing complexity of its vibrating body high, the processing cost high, the assembly error large, and it is difficult to achieve the goal of miniaturizing the actuator. Defect 2: For existing multi-degree-of-freedom actuators using a circular structure, the dispersed arrangement of their piezoelectric ceramics reduces the matching degree between the excitation region and the vibration mode, making it difficult to achieve strong electromechanical coupling under multiple vibration modes and restricting the mechanical output of the actuator.

[0035] Defect 3: Piezoelectric actuators powered by external power sources are difficult to achieve the design goals of lightweight and miniaturization, and the movement of the actuator is restricted by the power source and the length of the cable.

[0036] As Figure 1 shown, an ultrasonic actuator based on a circular non-uniformly distributed electrode includes: A carrier plate 70, an on-board circuit 60 is provided in the upper space of the carrier plate 70, and a circular piezoelectric ceramic plate 20 and a circular vibrating body are successively provided in the lower space of the carrier plate 70. Driving feet are provided on the lower bottom surface of the circular vibrating body. As Figure 2 shown, the driving feet include a front foot 30, a middle foot 40, and a rear foot 50.

[0037] In this embodiment, the circular piezoelectric ceramic plate 20 is adhered to the upper surface of the circular vibrating body, and the four driving feet are provided on the lower surface of the circular vibrating body; Among them, the angular difference between the front foot 30 and the rear foot 50 is 180°, and the two middle feet 40 are symmetrically distributed with respect to the line connecting the front foot 30 and the center of the circular vibrating body, with an interval angle of 56.25°; Among them, the radial distance from the center points of the front foot 30 and the middle foot 40 to the center point of the circular vibrating body is 23.5 mm, and the radial distance from the center point of the rear foot 50 to the center point of the circular vibrating body is 14 mm.

[0038] As a further implementation, the on-board circuit 60 is placed on top of the actuator, and the carrier board 70 can be used to isolate the actuator from the on-board circuit 60.

[0039] As a further implementation, the annular piezoelectric ceramic plate 2 is polarized in the thickness direction.

[0040] The actuator can achieve two motion modes: straight-line motion and rotational motion; When the actuator performs straight-line motion, the annular piezoelectric ceramic 20 divided into eight equal parts can be used to excite the circumferential fourth-order bending vibration mode, so as to improve the matching degree between the excitation region and the vibration mode, and further improve the electromechanical coupling coefficient; however, this division method will reduce the electromechanical coupling coefficient of the circumferential third-order bending vibration mode because the mode does not match the excitation region.

[0041] Similarly, when the actuator performs rotational motion, using the annular piezoelectric ceramic divided into six equal parts to excite the circumferential third-order bending vibration mode can improve the electromechanical coupling in this mode, but it is not applicable to the mode corresponding to straight-line motion.

[0042] From the above analysis, it can be seen that it is difficult to take into account the electromechanical coupling coefficients in two vibration modes by adopting the traditional method of uniformly pasting piezoelectric ceramics.

[0043] In order to balance the electromechanical coupling coefficients of the actuator in two vibration modes (i.e., two motion modes), the cutting lines with uniformly divided electrodes in the two vibration modes are superimposed, and finally the piezoelectric ceramics are divided into electrodes with multiple non-uniform parts. To excite a certain vibration mode, select the corresponding part of the piezoelectric ceramic electrode for excitation, so that the matching degree between the excitation region of the piezoelectric ceramics and the matrix vibration mode in the two motion modes can be relatively high.

[0044] Specifically, an annular piezoelectric ceramic plate with an outer diameter of 50 mm, an inner diameter of 25 mm, and a thickness of 1 mm is used. After dividing it into eight equal parts, any one of the dividing lines is selected as the starting line for the eight-equal-part division. After rotating it clockwise by 7.5°, it is used as the starting line for the six-equal-part division, and then the six-equal-part division is carried out based on this. Finally, the annular ceramic plate is divided into 14 non-uniform parts.

[0045] It can be understood that when dividing the non-uniform region on the annular piezoelectric ceramic plate, the specific rotation direction is not limited. For example, the starting line can also be rotated counterclockwise to obtain the required non-uniform parts.

[0046] In this embodiment, with the center of the annular piezoelectric ceramic plate 20 as the reference, a total of 14 electrodes, namely electrode a1 - electrode n14, are arranged in sequence along the circumferential direction. The area of each electrode region can be calculated through the angle of electrode division. The electrode division on the upper surface of the annular piezoelectric ceramic plate 20 is asFigure 4 as shown in the figure, where: Octant division, specifically: Electrodes c3 and j10 are at 180°, electrodes f6 + g7 and m13 + n14 are at 180°, electrodes a1 + b2 and h8 + i9 are at 180°, electrodes d4 + e5 and k11 + l12 are at 180°, thus forming an octant division of the annular piezoelectric ceramic plate 20. By exciting the electrodes, a circumferential fourth-order bending mode is formed to drive the actuator to generate a straight-line motion; Hexant division, specifically: Electrodes b2 + c3 + d4 form a group, electrodes g7 + h8 form a group, electrodes k11 + l12 form a group, and the above three groups of electrodes are at 120°; electrodes a1 + n14 form a group, electrodes e5 + f6 form a group, electrodes i9 + j10 + k11 form a group, and the above three groups of electrodes are at 120°; thus forming a hexant division of the annular piezoelectric ceramic plate 20. By exciting the electrodes, a circumferential third-order bending mode is formed to drive the actuator to generate a rotational motion.

[0047] Through the above division method, the angles of 14 electrode regions are obtained. Combining the inner and outer diameters of the electrodes, the areas of each electrode region are determined, which is used to determine the effective driving areas generated by each electrode region after the piezoelectric ceramic plate 20 is excited.

[0048] In this embodiment, it is illustrated by adding angles in the electrode division schematic diagram, Figure 4 as shown in the figure, specifically: The annular sector angles formed by electrodes a1, e5, h8, and l12 are all 37.5°; The annular sector angles formed by electrodes b2, i9, d4, and k11 are all 7.5°; The annular sector angles formed by electrodes c3 and j10 are all 45°; The annular sector angles formed by electrodes f6, g7, m13, and n14 are all 22.5°; Combining the inner and outer diameters of the annular piezoelectric ceramic plate 20, the areas of each electrode region can be calculated.

[0049] The electrodes of the piezoelectric ceramic plate adopt the above non-uniform division method, which balances the electromechanical coupling characteristics under two vibration modes without increasing the weight of the actuator. And since only the electrode division changes during the assembly process, the cost of its repeated assembly will not be significantly increased.

[0050] The displacement distribution curves of the two vibration modes in the circumferential direction are as Figure 3As shown, P1 is the point with the maximum vibration displacement of the fourth-order bending mode, and P2 is the midpoint of the gray area (when the front foot is arranged within the gray area, the counterclockwise rotation of the actuator can be achieved). The phase difference between point P1 and point P2 is 7.5°. To maximize the front foot during linear motion while enabling the counterclockwise rotation of the actuator, 7.5° is thus used as the angular offset between the two uniform division methods.

[0051] In this embodiment, the vibration modes of the multi-degree-of-freedom self-moving piezoelectric actuator based on the annular non-uniform electrode distribution are as Figure 5 and Figure 6 shown. Specifically: For the divided piezoelectric ceramics, as Figure 7 shown, when the excitation voltage UT1(t) = V 0 sin(2πf B4 t) is applied to electrodes a1, b2, d4, e5, h8, i9, k11, and l12 (i.e., the black area); When the excitation voltage UT2(t) = V 0 sin(2πf B4 t+π) is applied to electrodes c3, f6, g7, j10, m13, and n14 (i.e., the white area), a circumferential fourth-order bending mode can be excited at a frequency of 36.4 kHz, as Figure 6 shown. The standing wave generated by this mode exhibits the longitudinal vibration property along the ring on the vibrating body. Given the placement positions of the front foot 30 and the middle foot 40, macroscopically, the front foot 30 and the middle foot 40 alternately push the ground under the excitation of the bending standing wave, generating a radially downward oblique driving force, thereby driving the actuator to produce a straight-line motion.

[0052] Similarly, as Figure 8 shown, when the excitation voltage UR1(t)= V 0 sin(2πf B3 t) is applied to electrodes a1, e5, f6, i9, j10, k11, and n14 (i.e., the black area); When the excitation voltage UR2(t)= V 0 sin(2πf B3 t+π) is applied to electrodes b2, c3, d4, g7, h8, l12, and m13 (i.e., the white area), a circumferential third-order bending mode can be excited at a frequency of 20.6 kHz, as Figure 5As shown, the standing wave generated by this mode exhibits the property of longitudinal vibration along the ring on the vibrating body. Given the placement positions of its front legs 30 and middle legs 40, macroscopically, the front legs 30 and middle legs 40 alternately push the ground under the excitation of the bending standing wave, generating a circumferential downward oblique driving force, thereby driving the actuator to generate a rotational motion.

[0053] Among them, V 0 is the peak amplitude of the excitation voltage (i.e., the maximum amplitude of the voltage waveform), f B4 is the frequency of the excitation voltage when entering the fourth-order bending mode, and f B3 is the frequency of the excitation voltage when entering the third-order bending mode, 2π is a constant for converting the frequency to the angular frequency, t is the time variable.

[0054] As a further implementation method, the movement speed of the actuator can be adjusted by adjusting the amplitude of the excitation voltage.

[0055] In summary, after the unequal division of the annular piezoelectric ceramic electrodes, when the actuator moves straight, the voltage is applied to the electrode area that matches the movement of the driving feet, exciting the circumferential fourth-order bending mode, which can maximize the matching degree between the piezoelectric ceramic excitation area and the matrix vibration mode during straight movement; Similarly, when the actuator rotates, the voltage is applied to the electrode area that matches the movement of the driving feet, exciting the circumferential third-order bending mode, which can maximize the matching degree between the piezoelectric ceramic excitation area and the matrix vibration mode during rotational movement.

[0056] Therefore, the unequal division of the piezoelectric ceramic electrodes maximizes the matching degree between the excitation area of the annular piezoelectric ceramic plate and the vibration mode of the annular vibrating body in the two modes, thereby enhancing the electromechanical coupling characteristics of the two vibration modes as a whole and improving the mechanical output of the actuator.

[0057] To get rid of the constraints of the power supply and power supply cables and achieve the untethered movement of the piezoelectric actuator, this embodiment develops an integrated on-board drive circuit. By selectively exciting some electrodes, the straight movement or rotational movement of the actuator is realized, thereby reducing the circuit volume and the resource occupancy of the microcontroller I / O ports.

[0058] The circuit principle is as Figure 9As shown in the figure, the battery is connected to the boost circuit in the drive circuit, the battery is connected to the voltage regulator in the control circuit, and the remote control is connected to the wireless communication module in the control circuit. The drive circuit includes a boost circuit and two full-bridge drive circuits. The two full-bridge drive circuits are respectively connected to the isolation transformer in the isolation circuit to obtain transformer output I and transformer output II. In the control circuit, the voltage regulator and the wireless communication module are both connected to the STM32 main control chip. The STM32 main control chip selects the mode according to the instructions sent by the remote control, so that the actuator performs rotational motion or straight-line motion. The relay switch is electrically connected to the control circuit and the piezoelectric ceramic plate respectively.

[0059] The process of driving the actuator using the on-board circuit is as Figure 10 shown: The wireless communication module receives the remote control instructions sent by the remote control. After being processed by the STM32 microcontroller, the relevant instructions generate input signals I and II for the full-bridge drive circuit. The drive signals I and II output by the full-bridge drive circuit powered by the Boost boost circuit are input into the relay through the isolation transformer. The motion mode switching signal output by the microcontroller controls the relay to output different excitation signals, thereby realizing the dynamic switching of the piezoelectric ceramic electrode excitation area.

[0060] Compared with the existing actuators, the actuator proposed in this solution has the following advantages: Advantage 1: Different from the linear vibration mode of the traditional rectangular structure actuator, the vibration modes of the annular vibration body structure are mostly centrosymmetric, which helps to realize multi-degree-of-freedom motion. Moreover, the mechanical part of the proposed actuator is only composed of a simple ring and a piece of piezoelectric ceramic, with extremely simple structure, reducing the manufacturing cost, processing difficulty, and assembly complexity of the actuator.

[0061] Advantage 2: A non-uniform electrode division method is designed, and the complete ring is divided into 14 non-uniform parts. On the one hand, according to the required motion mode of the actuator, the corresponding ring vibration mode can be excited, and then the three-degree-of-freedom motion of straight-line and rotation in the plane can be realized. On the other hand, the non-uniform division of the piezoelectric ceramic plate electrodes can achieve a relatively high electromechanical coupling coefficient in both vibration modes, improving the mechanical output performance of the actuator.

[0062] Advantage 3: Using the on-board circuit to drive the actuator reduces the volume of the drive system, facilitating the miniaturization and integration of the actuator system. The actuator is free from the constraints of the power supply and the power supply cable, enhancing the controllability and being easy to realize multi-scenario applications.

[0063] In summary, this embodiment is based on Φ50×7.5 mm 3The actuator prototype uses a ring-shaped piezoelectric ceramic with non-uniformly distributed electrodes. The position distribution of the driving feet is designed according to the vibration mode, generating straight-line and rotational motions respectively in the fourth-order bending and third-order bending modes. In addition, the actuator can be driven and controlled through an on-board circuit. The designed on-board circuit has the characteristics of low cost, small weight, and small volume, enabling the untethered movement of the actuator. When powered by a power supply with a voltage of 400 V, the maximum straight-line and rotational speeds of the actuator are 138.2 mm / s (36.4 kHz) and 23.5 rad / s (20.6 kHz) respectively. In addition, the actuator can carry a load of 5130 g (the load-to-self-weight ratio is 156.4), which is superior to the performance of most traditional multi-degree-of-freedom ultrasonic actuators.

[0064] Embodiment 2: A working method of an ultrasonic actuator based on a ring with non-uniformly distributed electrodes includes the following steps: The electrodes in the eight equally divided regions are excited by a set excitation voltage and frequency, causing the ring-shaped vibrating body to enter the fourth-order circumferential bending mode. By alternately pushing the ground under the excitation of the bending standing wave by the front feet and middle feet, a radially downward oblique driving force is generated to drive the actuator to produce a straight-line motion; The electrodes in the six equally divided regions are excited by a set excitation voltage and frequency, causing the ring-shaped vibrating body to enter the third-order circumferential bending mode. By alternately pushing the ground under the excitation of the bending standing wave by the front feet and middle feet, a circumferentially downward oblique driving force is generated to drive the actuator to produce a rotational motion.

[0065] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An ultrasonic actuator based on annular non-uniformly distributed electrodes, characterized in that: It includes a carrier plate, the upper space of the carrier plate is provided with a board-mounted circuit, the lower space of the carrier plate is provided with an annular piezoelectric ceramic plate and an annular vibrating body in sequence, and the lower bottom surface of the annular vibrating body is provided with a driving foot; The surface of the annular piezoelectric ceramic plate has multiple electrodes arranged unevenly. Specifically, based on the center of the annular piezoelectric ceramic plate, it is divided into eight equal parts and six equal parts along the annular direction. Each equal part is provided with a corresponding electrode, and there is a set offset angle between the eight equal parts and the six equal parts.

2. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 1, characterized in that: The driving foot includes a front foot, a middle foot and a rear foot, the front foot and the rear foot are 180 degrees apart, and at least two middle feet are symmetrically distributed about the line connecting the front foot and the center of the annular vibrator, and the interval angle is a set value.

3. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 1, characterized in that: The electrodes in the eight equally divided areas are excited at the set excitation voltage and frequency, causing the annular vibrating body to enter the fourth-order bending mode in the circumferential direction.

4. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 3, characterized in that: In the fourth-order bending mode, the forefoot and the midfoot push the ground alternately under the excitation of the bending standing wave, generating a radial oblique downward driving force, driving the actuator to generate a straight motion.

5. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 1, characterized in that: The electrodes in the six equally divided areas are excited at the set excitation voltage and frequency, causing the annular vibrating body to enter the third-order bending mode in the circumferential direction.

6. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 5, characterized in that: In the third-order bending mode, the forefoot and the midfoot push the ground alternately under the excitation of the bending standing wave, generating a circumferential oblique downward driving force, driving the actuator to generate a rotational motion.

7. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 1, characterized in that: The movement speed of the actuator is adjusted by changing the amplitude of the excitation voltage.

8. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 1, characterized in that: The onboard circuit includes a drive circuit, a control circuit and an isolation circuit. The remote control is electrically connected to the wireless communication module in the control circuit, the piezoelectric ceramic piece is connected to the relay in the isolation circuit, and the battery is respectively connected to the voltage regulator in the control circuit and the boost circuit in the drive circuit; a full-bridge drive circuit is provided in the drive circuit, an isolation transformer is provided in the isolation circuit, and a microcontroller is provided in the control circuit.

9. The ultrasonic actuator based on annular non-uniformly distributed electrodes as claimed in claim 8, characterized in that: The wireless communication module receives remote control commands from the remote control, and generates input signals for the full-bridge drive circuit after processing by the microcontroller. The drive signal output by the full-bridge drive circuit is input into the relay through the isolation transformer. The motion mode switching signal output by the microcontroller controls the relay to output different excitation signals, thereby realizing dynamic switching of the piezoelectric ceramic electrode excitation area.

10. A working method of an ultrasonic actuator based on the annular non-uniformly distributed electrodes according to any one of claims 1 to 9, characterized in that: The following steps are involved: The electrodes in the eight equally divided areas are excited at the set excitation voltage and frequency, causing the annular vibrator to enter the fourth-order bending mode in the circumferential direction. The forefoot and the midfoot push the ground alternately under the bending standing wave excitation, generating a radial oblique downward driving force, driving the actuator to produce a straight motion. The electrodes in the six equally divided areas are excited at the set excitation voltage and frequency, causing the annular vibrator to enter a circumferential third-order bending mode. The forefoot and midfoot push the ground alternately under the excitation of the bending standing wave, generating a circumferential oblique downward driving force, driving the actuator to produce rotational motion.

Images