Piezoelectric stick-slip linear platform with compliant parallel four-bar linkage amplification mechanism

Abstract

The application discloses a compliant parallel four-bar linkage amplification mechanism type piezoelectric stick-slip linear platform, which comprises a base, a moving platform and a guide rail between the base and the moving platform; a driving unit on the base comprises a first reference arm, a third compliant circular arc hinge, a third connecting rod, a second connecting rod, a first connecting rod and a second compliant circular arc hinge; the third connecting rod is provided with a second driving foot which is pre-topped on a second moving rail; the driving unit further comprises a piezoelectric driving device, a first compliant circular arc hinge is arranged between an output end of the piezoelectric driving device and the first connecting rod, and the first connecting rod is located between the piezoelectric driving device and the second connecting rod. The whole compliant displacement amplification mechanism has the effects of increasing viscosity and reducing stick-slip, can significantly improve the load capacity and working bandwidth of the platform, and reduce the return displacement; under the condition of meeting the effective stroke of the second driving foot, the size of the driving actuator is as small as possible, the contradiction between the bandwidth of the driving actuator and the single-step displacement of the platform is solved, and the movement speed of the platform can be significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of nano-positioning technology, and relates to a large-stroke, high-resolution precision displacement actuator, and particularly to a compliant parallel four-bar amplification mechanism piezoelectric stick-slip linear platform. Background Technology

[0002] Piezoelectric stick-slip linear platforms are precision displacement actuators capable of achieving both millimeter- and centimeter-level large strokes and nanometer-level high resolution. Based on the inverse piezoelectric effect of piezoelectric materials, the difference in dynamic and static friction between the moving platform and the drive unit, caused by the asymmetric vibration of the piezoelectric actuator under an asymmetric sawtooth wave voltage, continuously accumulates the tiny displacements of the piezoelectric actuator, thus forming a continuous large-stroke displacement. Compared to electromagnetic linear platforms, piezoelectric stick-slip linear platforms offer advantages such as no magnetic field, ease of control, and absence of end effects and thrust fluctuations. Compared to inchworm-driven and ultrasonic resonant piezoelectric linear platforms, they offer advantages such as ease of miniaturization, simple drive control, and negligible hysteresis nonlinearity during rapid motion. Therefore, in micro- and nano-manipulation technologies requiring miniaturization, lightweight design, and absence of magnetic field interference, such as precision optical engineering, ultra-precision machining and measurement, micromachining, biomedicine, and aerospace, piezoelectric stick-slip linear platforms exhibit unique advantages. However, current piezoelectric stick-slip linear platforms still have the following shortcomings:

[0003] 1) The platform has a complex overall structure and a large volume;

[0004] 2) The assembly and adjustment process of the moving platform and drive unit is complex;

[0005] 3) The static friction between the moving platform and the drive unit is not easy to adjust precisely;

[0006] 4) When the moving platform and the drive unit are in a sliding state, there is a displacement return of the drive unit on the moving platform, resulting in slow platform speed and poor motion stability. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a compliant parallel four-bar amplification mechanism piezoelectric stick-slip linear platform that is reasonable in structure and layout, simple in assembly and adjustment of the moving platform and drive unit, easy to adjust the static friction between the moving platform and drive unit online with precision, low displacement backlash of the moving platform, fast movement speed, good stability and high positioning accuracy.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a compliant parallel four-bar linkage amplification mechanism piezoelectric stick-slip linear platform, including a base and a moving platform disposed above the base. A first fixed rail and a second fixed rail that are parallel to each other are fixed on the base. A first moving rail and a second moving rail that are parallel to each other are fixed on the moving platform. The first moving rail is guided and matched with the first fixed rail, and the second moving rail is guided and matched with the second fixed rail.

[0009] The base is provided with a drive unit, which includes a first reference arm parallel to the first fixed rail. The first reference arm has a third compliant circular arc hinge, a third connecting rod, a second connecting rod, a first connecting rod and a second compliant circular arc hinge connected in sequence on the side facing the second moving rail. The second compliant circular arc hinge and the third compliant circular arc hinge are respectively connected to the first reference arm.

[0010] The third link is equipped with a second drive foot that is pre-loaded onto the second moving rail;

[0011] The drive unit also includes a piezoelectric drive device, and a first compliant circular arc hinge is provided between the output end of the piezoelectric drive device and the first link. The first link is located between the piezoelectric drive device and the second link.

[0012] To optimize the above technical solution, the following measures were also taken:

[0013] The first link is equipped with a first drive foot pre-mounted on the second moving rail. The compliant parallel four-bar linkage guide mechanism, consisting of a first rigid block, a first compliant circular arc hinge, a first link, and a second compliant circular arc hinge, allows the first and second drive feet to move along the surface of the second moving rail, significantly improving the platform's stability.

[0014] In a preferred embodiment, the first and second links are inclined toward the piezoelectric drive device.

[0015] In a preferred embodiment, the drive unit further includes a second reference arm located between the first reference arm and the second moving rail; the piezoelectric drive device includes a first rigid block connected to the first compliant circular arc hinge, a first flexible thin plate connecting the first rigid block and the first reference arm, a second flexible thin plate connecting the first rigid block and the second reference arm, a drive actuator resting on the first rigid block, and a friction force adjusting actuator resting on the end of the drive actuator. The friction force adjusting actuator is a piezoelectric actuator used for online precision adjustment of the static friction between the moving platform and the drive unit, to achieve rapid driving of the moving platform under different loads and expand the speed range of the platform. The drive actuator is a piezoelectric actuator that provides a power source for the platform.

[0016] In a preferred embodiment, the base includes a first receiving groove for accommodating the drive unit, and a fixing screw pressing against the drive unit is provided on the side of the base.

[0017] In a preferred embodiment, a wedge is further provided in the first receiving groove. The wedge is located between the first reference arm and the first moving rail. The first reference arm has an inclined surface on the side facing the wedge for the wedge to slide. An adjusting screw is provided on the side of the base, pressing against the large end of the wedge. The adjusting screw is used to push the wedge to slide along the inclined surface. The adjusting screw is used to adjust the axial displacement of the wedge to pre-coarsely adjust the static friction between the platform and the drive unit.

[0018] In a preferred embodiment, the wedge has a plane that faces the first moving rail and is parallel to the first moving rail.

[0019] In a preferred embodiment, there are two first flexible plates and two second flexible plates. The compliant parallel guide mechanism composed of the first and second flexible plates ensures that the first rigid body moves only along the axial direction of the drive actuator, preventing the drive actuator and friction-adjusting actuator from bearing lateral loads and improving their service life.

[0020] In a preferred embodiment, the drive unit further includes a second receiving groove for accommodating the drive actuator and the friction adjusting actuator, the second receiving groove ensuring that the drive actuator and the friction adjusting actuator perform strict axial extension and retraction movements.

[0021] In a preferred embodiment, the first reference arm, the second reference arm, the third compliant circular arc hinge, the third link, the second drive foot, the second link, the first link, the first drive foot, the second compliant circular arc hinge, the first compliant circular arc hinge, the first flexible thin plate, the first rigid block, and the second flexible thin plate of the drive unit are an integrated structure.

[0022] Compared with the prior art, the compliant parallel four-bar amplification mechanism piezoelectric stick-slip linear platform of the present invention includes a base and a moving platform disposed above the base. A first fixed rail and a second fixed rail are fixed on the base, and a first moving rail and a second moving rail are fixed on the moving platform, both parallel to each other. The first moving rail is guided and matched with the first fixed rail, and the second moving rail is guided and matched with the second fixed rail. The base is provided with a driving unit, which includes a first reference arm parallel to the first fixed rail. On the side of the first reference arm facing the second moving rail, a third compliant circular arc hinge, a third connecting rod, a second connecting rod, a first connecting rod, and a second compliant circular arc hinge are sequentially connected. The second and third compliant circular arc hinges are respectively connected to the first reference arm. A second driving foot is pre-loaded onto the second moving rail on the third connecting rod. The driving unit also includes a piezoelectric driving device. A first compliant circular arc hinge is disposed between the output end of the piezoelectric driving device and the first connecting rod, and the first connecting rod is located between the piezoelectric driving device and the second connecting rod.

[0023] The compliant displacement amplification mechanism, composed of the third compliant circular arc hinge, the third link, the second link, the first link, and the second compliant circular arc hinge, has the effect of increasing adhesion and reducing slippage, which can significantly improve the platform's load capacity and working bandwidth, and reduce the return displacement. Under the condition of satisfying the effective stroke of the second drive foot, the size of the drive actuator is minimized as much as possible, which solves the contradiction between the drive actuator bandwidth and the platform's single-step displacement, and can significantly improve the platform's movement speed.

[0024] In summary, the advantages of this invention are:

[0025] 1) The platform has a simple and compact overall structure;

[0026] 2) The first reference arm, second reference arm, third compliant circular arc hinge, third link, second drive foot, second link, first link, first drive foot, second compliant circular arc hinge, first compliant circular arc hinge, first flexible thin plate, first rigid block and second flexible thin plate of the drive unit are integrated into one structure, avoiding the assembly and adjustment process.

[0027] 3) The static friction force between the moving platform and the drive unit has two adjustment methods: coarse and fine, and can also be precisely adjusted online;

[0028] 4) The platform adopts a compliant parallel four-bar linkage amplification mechanism, which has the effect of increasing viscosity and reducing slippage. That is, it increases the driving force in the viscous stage and reduces the displacement return in the sliding stage, which can significantly improve the platform's movement speed, increase the driving force and speed adjustment range.

[0029] 5) The platform has a dual-point drive with two drive groups, which can significantly improve the platform's motion stability. Attached Figure Description

[0030] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0031] Figure 2 yes Figure 1 A schematic diagram of the decomposition process;

[0032] Figure 3 yes Figure 2 A schematic diagram of the structure after removing the automatic platform;

[0033] Figure 4 yes Figure 3 A schematic diagram of the decomposition process;

[0034] Figure 5 This is an exploded view of the drive unit;

[0035] Figure 6 This is a schematic diagram of the internal structure of the drive unit;

[0036] Figure 7 This is a diagram illustrating the working status;

[0037] Figure 8 This is a timing diagram of the driving voltage of the present invention. Detailed Implementation

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

[0039] Figures 1 to 7 This is a schematic diagram of the structure of the present invention.

[0040] The reference numerals in the attached drawings are as follows: moving platform 1, base 2, first receiving groove 21, first fixed rail 31, first moving rail 32, second moving rail 33, second fixed rail 34, wedge block 4, plane 41, drive unit 5, first reference arm 51, inclined plane 511, second reference arm 52, third compliant arc hinge 53, third connecting rod 54, second drive foot 541, second connecting rod 55, first connecting rod 56, first drive foot 561, second compliant arc hinge 57, first compliant arc hinge 58, piezoelectric drive device 6, friction force adjusting actuator 61, drive actuator 62, first flexible thin plate 63, first rigid block 64, second receiving groove 65, second flexible thin plate 66, third flexible thin plate 67, fixing screw 71, adjusting screw 72, preload screw 73.

[0041] Figures 1 to 7 As shown in the figure, the compliant parallel four-bar amplification mechanism piezoelectric stick-slip linear platform of the present invention includes a base 2 and a moving platform 1 disposed above the base 2. A first fixed rail 31 and a second fixed rail 34 that are parallel to each other are fixed on the base 2. A first moving rail 32 and a second moving rail 33 that are parallel to each other are fixed on the moving platform 1. The first moving rail 32 is guided and matched with the first fixed rail 31, and the second moving rail 33 is guided and matched with the second fixed rail 34.

[0042] The base 2 is provided with a drive unit 5. The drive unit 5 includes a first reference arm 51 parallel to the first fixed rail 31. The first reference arm 51 has a third compliant arc hinge 53, a third connecting rod 54, a second connecting rod 55, a first connecting rod 56 and a second compliant arc hinge 57 connected in sequence on the side facing the second moving rail 33. The second compliant arc hinge 57 and the third compliant arc hinge 53 are respectively connected to the first reference arm 51.

[0043] The third link 54 is provided with a second drive foot 541 pre-mounted on the second moving rail 33;

[0044] The drive unit 5 also includes a piezoelectric drive device 6. A first compliant circular arc hinge 58 is provided between the output end of the piezoelectric drive device 6 and the first connecting rod 56. The first connecting rod 56 is located between the piezoelectric drive device 6 and the second connecting rod 55. The first compliant circular arc hinge 58 is close to the second compliant circular arc hinge 57, so that the displacement output from the piezoelectric drive device 6 can be amplified on the first connecting rod 56.

[0045] In the embodiments, such as Figures 2 to 7 As shown, the first link 56 is provided with a first drive foot 561 pre-mounted on the second moving rail 33. The compliant parallel four-bar linkage guide mechanism causes the first drive foot 561 and the second drive foot 541 to move against the surface of the second moving rail 33, which can significantly improve the stability of the platform.

[0046] In the embodiments, such as Figure 6 As shown, the first link 56 and the second link 55 are inclined toward the piezoelectric drive device 6.

[0047] In the embodiments, such as Figures 2 to 6 As shown, the drive unit 5 also includes a second reference arm 52 located between the first reference arm 51 and the second moving rail 33;

[0048] The piezoelectric drive device 6 includes a first rigid block 64 connected to a first compliant circular arc hinge 58, a first flexible thin plate 63 connecting the first rigid block 64 and the first reference arm 51, a second flexible thin plate 66 connecting the first rigid block 64 and the second reference arm 52, a drive actuator 62 resting on the first rigid block 64, and a friction force adjusting actuator 61 resting on the end of the drive actuator 62. The friction force adjusting actuator 61, employing a piezoelectric actuator, is used for online precision adjustment of the static friction between the moving platform 1 and the drive unit 5 to achieve rapid driving of the moving platform 1 under different loads and expand the platform's speed range. The drive actuator 62, also employing a piezoelectric actuator, provides a power source for the platform.

[0049] In the embodiments, such as Figure 4 As shown, the base 2 includes a first receiving groove 21 for accommodating the drive unit 5, and a fixing screw 71 pressing against the drive unit 5 is provided on the side of the base 2.

[0050] A third flexible plate 67 is connected between the first reference arm 51 and the second reference arm 52. The third flexible plate 67 rests against the fixed end of the friction force adjusting actuator 61, and a pre-tightening screw 73 is screwed into the drive unit laterally to hold the third flexible plate 67 in place.

[0051] In the embodiments, such as Figures 2 to 7 As shown, a wedge 4 is also provided in the first receiving groove 21. The wedge 4 is located between the first reference arm 51 and the first moving rail 32. The first reference arm 51 has an inclined surface 511 on the side facing the wedge 4 for the wedge 4 to slide. The side of the base 2 has an adjusting screw 72 that presses against the large end of the wedge 4. The adjusting screw 72 is used to push the wedge 4 to slide along the inclined surface 511. The adjusting screw 72 is used to adjust the axial displacement of the wedge 4 to pre-coarsely adjust the static friction between the platform 1 and the drive unit 5.

[0052] In the embodiments, such as Figure 4As shown, the wedge block 4 has a plane 41, which faces the first moving rail 32 and is parallel to the first moving rail 32.

[0053] In the embodiments, such as Figures 2 to 7 As shown, there are two first flexible thin plates 63 and two second flexible thin plates 66. The compliant parallel guide mechanism composed of the first flexible thin plates 63 and the second flexible thin plates 66 ensures that the first rigid body moves only along the axial direction of the drive actuator 62, avoiding lateral loads on the drive actuator 62 and the friction force adjusting actuator 61, and improving their service life.

[0054] In the embodiments, such as Figure 5 As shown, the drive unit 5 also includes a second receiving groove 65 for accommodating the drive actuator 62 and the friction force adjusting actuator 61. The second receiving groove 65 ensures that the drive actuator 62 and the friction force adjusting actuator 61 perform strict axial extension and retraction movements.

[0055] The working principle of this invention is as follows: Figure 7 As shown, let the direction from the first moving rail 32 to the second moving rail 33 be the positive y-axis, and the extension direction of the drive actuator 62 be the positive x-axis. Then, the process of the moving platform 1 moving along the positive direction within one motion cycle T is as follows:

[0056] The first step is to move the driving platform 1 along the positive x-axis by Δx1, with the driving foot carrying it. The specific steps are as follows: Figure 8 As shown, a voltage (ut) is slowly applied to the drive actuator 62, causing the slowly elongating actuator 62 to push the first rigid body to move along the positive x-axis. The first rigid body, via the first compliant circular arc hinge 58, pushes the first connecting rod 56 to move simultaneously along both the positive x- and y-axis. The second connecting rod 55 and the third connecting rod 54 also move simultaneously along the positive x- and y-axis along with the first connecting rod 56. The gradually increasing positive displacement of the drive foot on the second connecting rod 55 along the y-axis causes the friction between the first drive foot 561 and the second drive foot 541 and the moving platform 1 to gradually increase, resulting in a thickening effect and increased load capacity. Under the action of this friction, the moving platform 1 experiences a large positive displacement Δx1 along the x-axis.

[0057] The second step involves rapidly restoring the drive actuator 62, the first drive foot 561, and the second drive foot 541, while the moving platform 1 only experiences a slight reverse movement Δx2. The specific steps are as follows: Figure 6As shown, at time t1 when the extension of the drive actuator 62 reaches its maximum value, the drive actuator 62 is quickly de-energized until the voltage (ut) is 0 at time t2. Then, the drive actuator 62 quickly returns to its original position, and the other mechanisms also quickly return to their original positions. During the return process, the negative displacement of the drive feet along the y-axis gradually decreases, which gradually reduces the friction between the first drive feet 561 and the second drive feet 541 and the moving platform 1, i.e., produces a slip reduction effect, and the return displacement decreases. Due to inertia and slip reduction, the moving platform 1 will only follow the first drive feet 561 and the second drive feet 541 to produce a small reverse movement Δx2 along the return direction, ultimately achieving a positive movement Δx = Δx1 - Δx2 for the moving platform 1.

[0058] Similarly, by simply changing the timing of the voltage (ut) applied to the drive actuator 62—that is, by first rapidly applying voltage (ut) to the drive actuator 62 and then slowly de-energizing it—the reverse movement of the moving platform 1 can be achieved. The effect of reverse movement is weaker than that of forward movement.

[0059] The preferred embodiments of the present invention have been described, and various changes or modifications made by those skilled in the art will not depart from the scope of the present invention.

Claims

1. A compliant parallel four-bar linkage amplification mechanism piezoelectric stick-slip linear platform, comprising a base (2) and a moving platform (1) disposed above the base (2), characterized in that, The base (2) is fixed with a first fixed rail (31) and a second fixed rail (34) that are parallel to each other. The moving platform (1) is fixed with a first moving rail (32) and a second moving rail (33) that are parallel to each other. The first moving rail (32) is guided and matched with the first fixed rail (31), and the second moving rail (33) is guided and matched with the second fixed rail (34). The base (2) is provided with a drive unit (5), the drive unit (5) includes a first reference arm (51) parallel to the first fixed rail (31), the first reference arm (51) is provided with a third compliant circular arc hinge (53), a third connecting rod (54), a second connecting rod (55), a first connecting rod (56) and a second compliant circular arc hinge (57) connected in sequence on the side facing the second moving rail (33), the second compliant circular arc hinge (57) and the third compliant circular arc hinge (53) are respectively connected to the first reference arm (51); The third link (54) is provided with a second drive foot (541) pre-pushed on the second moving rail (33); The drive unit (5) further includes a piezoelectric drive device (6), and a first compliant circular arc hinge (58) is provided between the output end of the piezoelectric drive device (6) and the first connecting rod (56). The first connecting rod (56) is located between the piezoelectric drive device (6) and the second connecting rod (55). The first connecting rod (56) is provided with a first driving foot (561) pre-push on the second moving rail (33); The first link (56) and the second link (55) are inclined toward the piezoelectric drive device (6); The drive unit (5) further includes a second reference arm (52) located between the first reference arm (51) and the second moving rail (33); The piezoelectric drive device (6) includes a first rigid block (64) connected to a first compliant circular arc hinge (58), a first flexible thin plate (63) connecting the first rigid block (64) and the first reference arm (51), a second flexible thin plate (66) connecting the first rigid block (64) and the second reference arm (52), a drive actuator (62) abutting on the first rigid block (64), and a friction force adjusting actuator (61) abutting on the end of the drive actuator (62).

2. The compliant parallel four-bar linkage amplification mechanism piezoelectric stick-slip linear platform according to claim 1, characterized in that, The base (2) includes a first receiving groove (21) for accommodating the drive unit (5), and the base (2) is provided with a fixing screw (71) pressing against the drive unit (5) on its side.

3. The compliant parallel four-bar linkage amplification mechanism piezoelectric stick-slip linear platform according to claim 2, characterized in that, The first receiving groove (21) is also provided with a wedge (4), which is located between the first reference arm (51) and the first moving rail (32). The first reference arm (51) has an inclined surface (511) on the side facing the wedge (4) for sliding. The base (2) has an adjusting screw (72) on the side that is pressed against the large end of the wedge (4). The adjusting screw (72) is used to push the wedge (4) to slide along the inclined surface (511).

4. The compliant parallel four-bar linkage amplification mechanism piezoelectric stick-slip linear platform according to claim 3, characterized in that, The wedge (4) has a plane (41) facing the first moving rail (32) and parallel to the first moving rail (32).

5. The compliant parallel four-bar linkage amplification mechanism piezoelectric stick-slip linear platform according to claim 4, characterized in that, The number of the first flexible thin plate (63) and the second flexible thin plate (66) are two each.

6. The compliant parallel four-bar linkage amplification mechanism piezoelectric stick-slip linear platform according to claim 5, characterized in that, The drive unit (5) further includes a second receiving groove (65) for accommodating the drive actuator (62) and the friction force adjusting actuator (61).

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