A series-connected bipedal symmetrical piezoelectric stick-slip actuator

Abstract

This invention relates to the field of piezoelectric stick-slip actuators, and more particularly to a series-connected bipedal symmetrical piezoelectric stick-slip actuator. The series-connected bipedal symmetrical piezoelectric stick-slip actuator includes a stator mechanism, which comprises a flexible hinge mechanism and a piezoelectric stack; the flexible hinge mechanism contains the piezoelectric stack, and the flexible hinge mechanism and the piezoelectric stack constitute a flexible hinge mechanism group; the stator mechanism includes two symmetrically arranged flexible hinge mechanism groups, and the two piezoelectric stacks are inclined towards each other. Using the piezoelectric stack as the driving element, and with the piezoelectric stack positioned appropriately within the stator mechanism, the displacement output of the piezoelectric stack is amplified through the flexible hinge mechanism. Two sets of voltage U... A and U B Two piezoelectric stacks are applied to the drive mechanism respectively. Under the action of the drive signal, the stacks begin to operate alternately, thereby effectively suppressing the retraction motion of the drive mechanism and improving the load capacity of the driver.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric stick-slip actuator technology, and in particular to a series-connected bipedal symmetrical piezoelectric stick-slip actuator. Background Technology

[0002] With the continuous advancement of science and technology and the rapid development of precision manufacturing technology, the requirements for high-precision actuation at the micro- and nano-level are becoming increasingly stringent, leading to a continuous increase in the demand for micro- and nano-precision actuators. Compared to traditional electromagnetic, hydraulic, and pneumatic actuators, novel actuators employing piezoelectric technology are more in line with the current technical needs of precision manufacturing. Piezoelectric actuators possess advantages such as simple structure, high precision, low energy consumption, small size, and immunity to electromagnetic interference, playing a crucial role in precision manufacturing fields such as biomedicine, optical precision engineering, biomedicine, and biomimetic robotics. Piezoelectric actuators primarily use piezoelectric materials as driving elements. Through the inverse piezoelectric effect, the piezoelectric material produces a certain deformation output, the magnitude of which can be controlled within a certain range by adjusting the voltage. Piezoelectric multilayer ceramics, commonly known as piezoelectric stacks, can achieve greater deformation output and higher thrust compared to piezoelectric ceramic sheets. Piezoelectric actuators using piezoelectric stacks as driving elements can meet the technical requirements of precision driving and micro-positioning. Based on their working principle, piezoelectric actuators can be classified into direct-acting actuators, inchworm actuators, ultrasonic actuators, and stick-slip actuators, among others. Compared to the wear and heat generation and complex signal control systems of other types of piezoelectric actuators, stick-slip actuators have been widely used in the field of long-stroke positioning due to their comprehensive performance of simple structure, simple control and high precision.

[0003] However, traditionally designed stick-slip actuators generally suffer from a backlash phenomenon. A stick-slip actuator's motion cycle includes two processes: "sticking" and "sliding." During the "sticking" process, the piezoelectric stack slowly elongates, and the actuator moves forward under the influence of static friction. During the "sliding" process, the piezoelectric stack rapidly contracts to its original length, and the actuator moves backward a small distance under the influence of dynamic friction. This backlash leads to problems such as short stroke and insufficient load capacity in stick-slip linear actuators. To suppress this backlash, some stick-slip actuators employ signal control methods, using signal modulation to avoid displacement output errors caused by the piezoelectric stack's hysteresis effect. However, closed-loop control introduces complex signal programming and control problems. In conclusion, backlash significantly impacts the performance of stick-slip actuators. Summary of the Invention

[0004] The purpose of this invention is to provide a series-connected bipedal symmetrical piezoelectric stick-slip actuator, which can solve the problem that the retraction motion in the prior art can affect the performance of the piezoelectric stick-slip actuator to a certain extent.

[0005] The present invention provides a series bipedal symmetrical piezoelectric stick-slip actuator, which includes a stator mechanism, wherein the stator mechanism includes a flexible hinge mechanism and a piezoelectric stack;

[0006] The flexible hinge mechanism is equipped with a piezoelectric stack, and the flexible hinge mechanism and the piezoelectric stack constitute a flexible hinge mechanism group.

[0007] The stator mechanism includes two symmetrically arranged flexible hinge mechanism groups, and the two piezoelectric stacks are inclined towards each other.

[0008] Preferably, the angle between the centerline of the piezoelectric stack and the symmetry line of the two flexible hinge mechanism groups is 20°.

[0009] Preferably, the flexible hinge mechanism includes an upper crossbeam, a lower crossbeam, a left longitudinal beam, and a right longitudinal beam;

[0010] The upper and lower crossbeams are arranged opposite to each other, and the left and right longitudinal beams are arranged opposite to each other.

[0011] The upper crossbeam, right longitudinal beam, lower crossbeam, and left longitudinal beam are connected in sequence to form a rectangular structure;

[0012] The two ends of the piezoelectric stack abut against the inner sides of the upper and lower crossbeams, respectively.

[0013] Flexible hinges are provided on the left and right longitudinal beams;

[0014] A drive foot is provided on the outer side of the upper crossbeam.

[0015] Preferably, the flexible hinge is an arc-shaped hinge or a Z-shaped hinge.

[0016] Preferably, one of the left longitudinal beam and the right longitudinal beam is provided with an arc-shaped hinge, and the other is provided with a Z-shaped hinge.

[0017] Preferably, the upper crossbeam has an installation groove on its inner side, and the lower crossbeam has pre-tightening screws.

[0018] The upper end of the piezoelectric stack is located in the mounting groove, and the lower end of the piezoelectric stack abuts against the preload screw.

[0019] Preferably, the series-connected bipedal symmetrical piezoelectric stick-slip actuator further includes a base;

[0020] The lower crossbeam is fixed to the base.

[0021] Preferably, the two flexible hinge mechanisms are connected to the same connecting seat;

[0022] The two ends of the connecting seat are respectively connected to the lower crossbeam of a flexible hinge mechanism, and the connecting seat and the flexible hinge mechanism are an integral mechanism.

[0023] The two flexible hinge mechanisms are mounted on the base via connecting seats.

[0024] Preferably, the base is provided with a stator support block, and the connecting seat is mounted on the support block.

[0025] Preferably, the series-connected bipedal symmetrical piezoelectric stick-slip actuator further includes a mover and a load platform;

[0026] The moving element includes two symmetrically arranged guide rails, which are slidably connected to the base.

[0027] The two flexible hinge mechanisms are disposed between the two guide rails, and the driving foot of the two flexible hinge mechanisms abuts against one of the guide rails;

[0028] The load platform is fixedly connected to the guide rail.

[0029] Beneficial effects:

[0030] A piezoelectric stack is used as the driving element, and its position is strategically placed within the stator mechanism. The displacement output of the piezoelectric stack is amplified via a flexible hinge mechanism. Two sets of voltages U... A and U B Two piezoelectric stacks are applied to the drive mechanism respectively. Under the action of the drive signal, the stacks begin to operate alternately, thereby effectively suppressing the retraction motion of the drive mechanism and improving the load capacity of the driver. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 A schematic diagram of the stator mechanism provided for a specific embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the three-dimensional structure of a series-connected bipedal symmetrical piezoelectric stick-slip actuator provided for a specific embodiment of the present invention;

[0034] Figure 3A three-dimensional structural diagram of a series bipedal symmetrical piezoelectric stick-slip actuator (without load platform) provided for a specific embodiment of the present invention;

[0035] Figure 4 A top view of a series-connected bipedal symmetrical piezoelectric stick-slip actuator (without load platform) provided for a specific embodiment of the present invention;

[0036] Figure 5 The driving voltage signal applied to the piezoelectric stack under normal operating conditions by the series-connected bipedal symmetrical piezoelectric stick-slip actuator provided in the specific embodiment of the present invention;

[0037] Figure 6 The diagram illustrates the working principle of the series-connected bipedal symmetrical piezoelectric stick-slip actuator within one cycle, as provided in a specific embodiment of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1: Stator mechanism; 2: Flexible hinge mechanism; 3: Piezoelectric stack; 4: Drive foot; 5: Arc hinge; 6: Z-type hinge; 7: Preload screw; 8: Base; 9: Support block; 10: Guide rail; 11: Load platform. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] like Figure 1 As shown, this embodiment provides a series bipedal symmetrical piezoelectric stick-slip actuator, which includes a stator mechanism 1, the stator mechanism 1 including a flexible hinge mechanism 2 and a piezoelectric stack 3.

[0044] The flexible hinge mechanism 2 is equipped with a piezoelectric stack 3. The flexible hinge mechanism 2 and the piezoelectric stack 3 constitute the flexible hinge mechanism 2 group.

[0045] The stator mechanism 1 includes two symmetrically arranged flexible hinge mechanisms 2, and the two piezoelectric stacks 3 are inclined towards each other.

[0046] In this embodiment, a piezoelectric stack 3 is used as the driving element, and the piezoelectric stack 3 is positioned appropriately in the stator mechanism 1. The displacement output of the piezoelectric stack 3 is amplified by the flexible hinge mechanism 2. Two sets of voltages U A and U B Two piezoelectric stacks 3 are applied to the drive mechanism respectively. Under the action of the drive signal, the stacks begin to operate alternately, thereby effectively suppressing the retraction motion of the drive mechanism and improving the load capacity of the driver.

[0047] In this embodiment, a specific structure of the stator mechanism 1 is also provided, as described below:

[0048] The angle between the centerline of the piezoelectric stack 3 and the symmetry line of the two flexible hinge mechanisms 2 is 20°.

[0049] The flexible hinge mechanism 2 includes an upper crossbeam, a lower crossbeam, a left longitudinal beam, and a right longitudinal beam. The upper and lower crossbeams are arranged opposite each other, and the left and right longitudinal beams are arranged opposite each other. The upper, right, lower, and left longitudinal beams are connected sequentially to form a rectangular structure. The two ends of the piezoelectric stack 3 abut against the inner sides of the upper and lower crossbeams, respectively. Flexible hinges are provided on the left and right longitudinal beams. A drive foot 4 is provided on the outer side of the upper crossbeam.

[0050] The flexible hinge is either an arc-shaped hinge 5 or a Z-shaped hinge 6. Of course, in this embodiment, the hinge can also adopt other structural forms.

[0051] Under the deflection deformation of the flexible hinge, the output displacement of the piezoelectric stack 3 is amplified, thereby improving the output performance of the driver.

[0052] One of the left and right longitudinal beams is equipped with an arc-shaped hinge 5, and the other is equipped with a Z-shaped hinge 6.

[0053] The two different flexible hinges result in inconsistent structural stiffness of the flexible mechanism. When the piezoelectric stack 3 generates displacement output, it can undergo deflection deformation to achieve coupling of driving displacement and has good output performance.

[0054] Flexible hinges are the basic deformation units of flexible mechanisms. The angular deformation of flexible hinges plays an important role in the main deformation of flexible mechanisms. Among them, straight circular hinges and Z-type hinges are relatively simple in structure, easy to design and manufacture, and are widely used.

[0055] The Z-type hinge 6 means that the left or right longitudinal beam is a two-section structure, and the two sections are staggered and parallel, and the two sections are connected by a connecting beam, which is perpendicular to the two sections.

[0056] Furthermore, on the two longitudinal beams of the flexible hinge mechanism 2, one is equipped with an arc-shaped hinge 5 and the other with a Z-shaped hinge 6. The longitudinal beam on one side of the two hinge mechanisms, which are adjacent to each other, is equipped with a Z-shaped hinge 6, while the longitudinal beam on the other side is equipped with an arc-shaped hinge 5.

[0057] An installation groove is provided on the inner side of the upper crossbeam, and a pre-tightening screw 7 is provided on the lower crossbeam. The upper end of the piezoelectric stack 3 is located in the installation groove, and the lower end of the piezoelectric stack 3 abuts against the pre-tightening screw 7. By adjusting the pre-tightening screw 7, the piezoelectric stack 3 can be pre-tightened within the flexible hinge mechanism 2.

[0058] Reference Figures 2 to 4 The series-connected bipedal symmetrical piezoelectric stick-slip actuator also includes a base 8, with the lower crossbeam fixed on the base 8.

[0059] Furthermore, the two flexible hinge mechanisms 2 are connected to the same connecting seat, with each end of the connecting seat connected to the lower crossbeam of one of the flexible hinge mechanisms 2. The connecting seat and the flexible hinge mechanism 2 are an integral unit. The two flexible hinge mechanisms 2 are mounted on the base 8 via the connecting seat. A stator support block 9 is provided on the base 8, and the connecting seat is mounted on the support block 9.

[0060] The series bipedal symmetrical piezoelectric stick-slip actuator also includes a mover and a load platform 11. The mover includes two symmetrically arranged guide rails 10, which are slidably connected to the base 8.

[0061] Two flexible hinge mechanisms 2 are disposed between two guide rails 10, and the driving feet 4 of the two flexible hinge mechanisms 2 abut against one of the guide rails 10. The load platform 11 is fixedly connected to the guide rail 10.

[0062] The stator mechanism 1 has a flexible hinge structure. After the displacement output of the piezoelectric stack 3 is amplified by the flexible hinge, it generates coupled motion in the lateral and longitudinal directions, thereby driving the mover to move, and in turn driving the motion output of the load platform 11.

[0063] In summary, the series-connected bipedal symmetrical piezoelectric stick-slip actuator provided in this embodiment has the following advantages:

[0064] This series-connected bipedal symmetrical piezoelectric stick-slip actuator uses a piezoelectric stack 3 as the driving element. The driving displacement is coupled through a series-connected bipedal symmetrical flexible mechanism, and is driven by two sets of excitation signals U. A and U B By driving piezoelectric stacks A and B respectively, the backlash motion generated during the stick-slip process is effectively suppressed, thereby improving the load capacity of the actuator.

[0065] The series bipedal symmetrical flexible mechanism has a flexible hinge structure. Different types of hinge combinations cause changes in the structural stiffness of the flexible mechanism. The angular deformation generated by the flexible hinge helps to realize the displacement drive of the series bipedal symmetrical flexible mechanism.

[0066] The stator mechanism 1 has two driving feet 4 symmetrically distributed, which can obtain stable motion performance and effectively reduce the influence of the different displacement output caused by the hysteresis effect of the two sets of piezoelectric stacks 3.

[0067] The stator mechanism 1 has a simple structure and is easy to process and assemble.

[0068] Reference Figure 5 , Figure 6 To further illustrate the above-described series-connected bipedal symmetrical piezoelectric stick-slip actuator, this embodiment also provides the following description of the operation process of the series-connected bipedal symmetrical piezoelectric stick-slip actuator within one signal cycle:

[0069] (1) During the time interval t0 to t1, the voltage U A As the piezoelectric stack 3A slowly rises, it extends gradually. The left-side drive section of the actuation mechanism deflects at a small angle along the positive x-axis, producing a small displacement in the positive X and Y axes respectively. Simultaneously, the voltage U... BAs the speed gradually decreases to zero, the right-side drive section of the actuator will deflect at a small angle in the positive x-axis direction due to the restoring effect of the flexible hinge mechanism 2. Under the combined action of the left and right drive legs 4, the actuator achieves linear motion along the positive x-axis.

[0070] (2) During the time interval t1 to t2, the voltage U B The piezoelectric stack 3 rapidly increases from zero to its maximum value. B Upon rapid stretching, the right-side drive section of the actuator will quickly deflect along the negative x-axis, reaching its limit position. Simultaneously, the voltage U... A The upward trend remains slow, with the left drive section of the actuator continuing to deflect along the X-axis. Since the elongation rate of the piezoelectric stack 3B is much faster than that of the piezoelectric stack 3A, the friction between the right drive feet 4 can be considered kinetic energy, while the friction between the left drive feet is less than static friction. Because the left drive foot 4 continues to deflect along the positive X-axis, driving the actuator, the retraction phenomenon can be effectively suppressed.

[0071] (3) During the time interval t2 to t3, the voltage U A The piezoelectric stack 3A extends as it slowly rises until it reaches its maximum value. Meanwhile, the left-side drive mechanism continues to deflect along the positive x-axis until it reaches its limit position. Simultaneously, the voltage U... B Starting from its maximum value, the piezoelectric stack 3B slowly contracts as it gradually decreases. During this process, due to the restoring force of the flexible hinge, the right drive part of the actuation mechanism gradually deflects in the positive X-axis direction. Under the combined action of the left and right drive legs 4, the actuator continues to move in the positive X-axis direction.

[0072] (4) During the time interval t3 to t4, the voltage UA rapidly drops from its maximum value to zero, the piezoelectric stack 3A contracts rapidly, and the left drive part of the actuation mechanism deflects rapidly in the negative X-axis direction. During this process, the dynamic friction between the left drive foot 4 and the slider is greater than the static friction, so a relative displacement occurs between the left drive foot 4 and the slider, resulting in motion in the negative X-axis direction. Simultaneously, the voltage U... B As the piezoelectric stack 3B slowly descends and contracts, the right-side drive part of the actuation mechanism continues to deflect along the positive direction of the X-axis. Therefore, under the action of the right-side drive foot 4, the retraction phenomenon caused by the contraction of the piezoelectric stack 3A is effectively mitigated.

[0073] Based on the working principle described above, it can be concluded that within one motion cycle, the two driving feet 4 of the stator mechanism 1 are driven simultaneously, and the piezoelectric stack 3 alternately elongates and contracts in sequence. Within four short time periods, it maintains positive displacement output in the X-axis direction, effectively suppressing any possible backlash.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A series-connected bipedal symmetrical piezoelectric stick-slip actuator, characterized in that, Includes a stator mechanism, which comprises a flexible hinge mechanism and a piezoelectric stack; The flexible hinge mechanism is equipped with a piezoelectric stack, and the flexible hinge mechanism and the piezoelectric stack constitute a flexible hinge mechanism group. The stator mechanism includes two symmetrically arranged flexible hinge mechanism groups, and the two piezoelectric stacks are inclined towards each other. The flexible hinge mechanism includes an upper crossbeam, a lower crossbeam, a left longitudinal beam, and a right longitudinal beam; The upper and lower crossbeams are arranged opposite to each other, and the left and right longitudinal beams are arranged opposite to each other. The upper crossbeam, right longitudinal beam, lower crossbeam, and left longitudinal beam are connected in sequence to form a rectangular structure; The two ends of the piezoelectric stack abut against the inner sides of the upper and lower crossbeams, respectively. Flexible hinges are provided on the left and right longitudinal beams; A drive foot is provided on the outer side of the upper crossbeam; The flexible hinge is an arc hinge or a Z-shaped hinge; One of the left longitudinal beam and the other of the right longitudinal beam are provided with an arc-shaped hinge and the other with a Z-shaped hinge. The series-connected bipedal symmetrical piezoelectric stick-slip actuator also includes a base; The lower crossbeam is fixed to the base; The two flexible hinge mechanisms are connected to the same connecting seat; The two ends of the connecting seat are respectively connected to the lower crossbeam of a flexible hinge mechanism, and the connecting seat and the flexible hinge mechanism are an integral mechanism. The two flexible hinge mechanisms are mounted on the base via connecting seats.

2. The series-connected bipedal symmetrical piezoelectric stick-slip actuator according to claim 1, characterized in that, The angle between the centerline of the piezoelectric stack and the line of symmetry of the two flexible hinge mechanism groups is 20°.

3. The series-connected bipedal symmetrical piezoelectric stick-slip actuator according to claim 1, characterized in that, The upper crossbeam has an installation groove on its inner side, and the lower crossbeam has a pre-tightening screw. The upper end of the piezoelectric stack is located in the mounting groove, and the lower end of the piezoelectric stack abuts against the preload screw.

4. The series-connected bipedal symmetrical piezoelectric stick-slip actuator according to claim 1, characterized in that, The base is provided with a stator support block, and the connecting seat is installed on the support block.

5. The series-connected bipedal symmetrical piezoelectric stick-slip actuator according to claim 3, characterized in that, The series-connected bipedal symmetrical piezoelectric stick-slip actuator also includes a mover and a load platform; The moving element includes two symmetrically arranged guide rails, which are slidably connected to the base. The two flexible hinge mechanisms are disposed between the two guide rails, and the driving foot of the two flexible hinge mechanisms abuts against one of the guide rails; The load platform is fixedly connected to the guide rail.

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