Rigidity-optimized compliant driving mechanism for piezoelectric stick-slip positioning

Abstract

The rigidity-optimized flexible driving mechanism comprises a flexible unit, a pre-tightening piece and piezoelectric ceramics, a clamping groove is formed in the flexible unit, a friction material is arranged in the clamping groove, the piezoelectric ceramics are arranged on the flexible unit, and the friction material is arranged in the clamping groove. The piezoelectric ceramic and the compliant unit are connected through the pre-tightening piece, and the piezoelectric ceramic is pre-tightened through torque adjustment of the pre-tightening piece. The compliant unit can be designed into a first compliant unit, a second compliant unit, a third compliant unit and a fourth compliant unit, and input rigidity and output rigidity performance are changed through changes of physical characteristics of the first compliant unit, the second compliant unit, the third compliant unit and the fourth compliant unit so as to better adapt to different output environments.

Description

Technical Field

[0001] The invention relates to the field of precision positioning and applications, and in particular to a stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning. Background Art

[0002] For the kinematic pairs composed of traditional mechanical structures, such as the rack-driven moving pair in the gear rack mechanism and the rotating pair at the connection of the multi-link mechanism, the main parts of the kinematic pairs are the slide rails, sliders, bearings, etc. However, for precision positioning technology, these components have obvious shortcomings: first, such mechanisms are composed of separate parts, and the processing accuracy and assembly accuracy of the parts have a huge impact on the accuracy of the final kinematic pair. In order to improve these accuracies, huge costs are required; second, such mechanisms are limited by their own mechanical motion principles, and are bulky and difficult to integrate. The driving part of the traditional kinematic pair is mostly motors, cylinders, hydraulic cylinders, etc., which are limited by the driving principles of these driving components. Manufacturing a driving component with both small size and high precision also faces great cost and feasibility issues. In contrast, the compliant part of the stick-slip piezoelectric compliant unit adopts an integrated design, combining the kinematic pair into the compliant unit. It has the characteristics of high precision, no gap, simple structure, no friction and wear, no assembly, large load capacity and easy miniaturization, and can be integrally formed by machining methods such as wire cutting, overcoming the cost and volume problems of the kinematic pairs composed of traditional mechanical structures. The piezoelectric ceramics in the driving part of the stick-slip piezoelectric compliance unit use the inverse piezoelectric effect to convert the input electrical energy into mechanical force and mechanical displacement, and achieve displacement output from micrometer to nanometer levels.

[0003] Among the existing piezoelectric compliant actuators, there are many design precedents for large stroke and high precision, but there are few designs that compare the use of different compliant unit structures for stiffness adjustment. Therefore, it is necessary to explore the impact of different structures on stiffness in order to analyze the impact of input stiffness and output stiffness.

[0004] Ren Zhisheng et al. disclosed in the Chinese invention patent CN114567200A a "compliant parallel four-link amplifying mechanism piezoelectric stick-slip linear platform". The disclosed compliant unit is composed of a connecting rod and a compliant circular hinge, which realizes the change of force and displacement from the input of the piezoelectric ceramic drive device to the output of the driving foot. Not only is the structure simple, but the driving foot is a material structure integrated with the compliant unit, which will cause relatively large losses due to friction, and even cause permanent damage to the mechanism. Summary of the invention

[0005] In order to solve at least one of the problems existing in the prior art, the present invention provides a stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning, which can change the input stiffness and output stiffness performance by changing the physical characteristics of the first compliant unit, the second compliant unit, the third compliant unit, and the fourth compliant unit proposed by the present invention to better adapt to different output environments.

[0006] In order to achieve the purpose of the present invention, the present invention provides a stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning, including a compliant unit, a preload and a piezoelectric ceramic, wherein the compliant unit is provided with a slot, a friction material is provided in the slot, the piezoelectric ceramic is provided on the compliant unit, and the piezoelectric ceramic and the compliant unit are connected by the preload and the preload of the piezoelectric ceramic is achieved by adjusting the torque of the preload.

[0007] In the compliance unit, when the piezoelectric ceramics are properly pre-tightened by the pre-tightening screws, the piezoelectric ceramics can be controlled by voltage signals to achieve output performance with different characteristics. It has the advantages of simple structure, strong interchangeability and low cost.

[0008] The input voltage signal of the piezoelectric ceramic is a sawtooth wave, and the elongation of the piezoelectric ceramic is positively correlated with the voltage. The voltage signal of the piezoelectric ceramic is a sawtooth wave input, which is converted into an output at the card slot through the physical structure of the compliance unit itself, so that the card slot drives the friction material to move slowly in a certain direction in the horizontal direction and then quickly retreat. When the sawtooth wave signal is in a slow increase, static friction is generated between the friction material of the card slot and the object in friction contact, and the friction material and the object in friction contact move together in the elongation direction of the piezoelectric ceramic; when the sawtooth wave signal is in a fast decrease, the card slot drives the friction material to move quickly. Due to the inertia of the object in friction contact itself, there is a certain friction contact between the friction material of the card slot and the external object and the friction material, and the friction material can move a distance parallel to the elongation direction of the piezoelectric ceramic. The friction material drives the friction contact object to retreat along the shortening direction of the piezoelectric ceramic for a displacement smaller than the forward motion. Through the periodic change of the sawtooth wave signal, the output of linear motion is realized through the stick-slip motion principle.

[0009] Furthermore, the compliance unit is a first compliance unit, which includes a first fixed rigid part and a first diamond-shaped amplifying mechanism located on the first fixed rigid part, a first movable rigid part, a first rotating compliance hinge, a second movable rigid part, a parallel contact lever and a lever-type amplifying mechanism rotating hinge, and the card slot provided on the first compliance unit is a first card slot,

[0010] The first diamond-shaped amplifying mechanism, the first movable rigid part, the first rotationally flexible hinge and the second movable rigid part are connected in sequence. The piezoelectric ceramic is arranged in the first diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the first diamond-shaped amplifying mechanism to deform to store elastic energy. The second movable rigid part is connected to the first card slot through a parallel contact lever at the top and is connected to the first fixed rigid part through a lever-type amplifying mechanism rotation hinge at the bottom.

[0011] The first compliance unit flexibly amplifies and reduces the output force and output displacement of the piezoelectric compliance driver through the coordination of the first diamond-shaped amplifier mechanism, the first rotating compliance hinge, the parallel contact lever, the lever-type amplifier mechanism rotating hinge and other structures. The first compliance unit can independently design the output force, output speed, resolution, etc. of the stiffness-optimized compliant drive mechanism used for piezoelectric stick-slip positioning by changing its internal geometric features.

[0012] Furthermore, the compliant unit is a second compliant unit, which includes a second fixed rigid part and a second rhombus amplifying mechanism located on the second fixed rigid part, a third movable rigid part, a first flexible contact cantilever beam, a parallelogram preloaded compliant beam and a preload adjustment seat, and the slot provided on the second compliant unit is a second slot.

[0013] The second diamond-shaped amplifying mechanism, the third movable rigid part, the first flexible contact cantilever beam and the second slot are connected in sequence, the piezoelectric ceramic is arranged in the second diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the second diamond-shaped amplifying mechanism to deform to store elastic energy;

[0014] The parallelogram preloaded compliant beam comprises at least two support beams, one of which is connected to the second slot and the second fixed rigid part, the other support beam is provided with the preload adjustment seat, and a preload hole is provided on the second fixed rigid part and at a position opposite to the preload adjustment seat.

[0015] Furthermore, the input and output stiffnesses are adjusted by adjusting the number of support beams connecting the second slot and the second fixed rigid portion.

[0016] Furthermore, the compliant unit is a third compliant unit, which includes a third fixed rigid part and a third diamond-shaped amplifying mechanism located on the third fixed rigid part, a fourth movable rigid part, a second flexible contact guide beam, a fifth movable rigid part, a vertical pre-tightening compliant beam and a horizontal pre-tightening compliant beam, and the card slot provided on the third compliant unit is a third card slot.

[0017] The third diamond-shaped amplifying mechanism, the fourth movable rigid part, the second flexible contact guide beam, the fifth movable rigid part and the third slot are connected in sequence, the piezoelectric ceramic is arranged in the third diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the third diamond-shaped amplifying mechanism to deform to store elastic energy;

[0018] The vertical pre-tensioned compliant beam and the horizontal pre-tensioned compliant beam are perpendicular to each other and connected in series. The vertical pre-tensioned compliant beam is connected to both the fifth movable rigid part and the third fixed rigid part. The vertical pre-tensioned compliant beam is used to generate deformation displacement in the left and right directions of the third compliant unit, and the horizontal pre-tensioned compliant beam is used to generate deformation displacement in the up and down directions of the third compliant unit.

[0019] Furthermore, the input stiffness can be increased or decreased by changing the span, width, and number of parallel beams of the vertical preloaded compliant beam.

[0020] Furthermore, the output stiffness can be increased or decreased by changing the span, width, and number of parallel beams of the horizontal preloaded compliant beam.

[0021] Furthermore, the compliant unit is a fourth compliant unit, which includes a fourth fixed rigid part and a fourth diamond-shaped amplifying mechanism located on the fourth fixed rigid part, a sixth movable rigid part, a third flexible contact guide beam, a fourth slot and a "Z"-shaped pre-tightening compliant beam, and the slot provided on the fourth compliant unit is a fourth slot.

[0022] The fourth diamond-shaped amplifying mechanism, the sixth movable rigid part, the third flexible contact guide beam, the fourth slot and the "Z"-shaped pre-tightening compliant beam are connected in sequence, and the end of the "Z"-shaped pre-tightening compliant beam is connected to the fourth fixed rigid part. The piezoelectric ceramic is arranged in the fourth diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the fourth diamond-shaped amplifying mechanism to deform to store elastic energy, wherein the beam direction in the "Z"-shaped pre-tightening compliant beam is at a certain angle to the input force direction of the piezoelectric ceramic and the pressure direction of the friction material of the fourth slot.

[0023] Furthermore, the input stiffness and the output stiffness are adjusted by changing the angle between the beam direction in the "Z"-shaped preloaded compliant beam and the input force direction of the piezoelectric ceramic and the pressure direction of the friction material on the fourth slot.

[0024] The first compliant unit, the second compliant unit, the third compliant unit and the fourth compliant unit are configured and designed with a first diamond-shaped amplifying mechanism, a second diamond-shaped amplifying mechanism, a third diamond-shaped amplifying mechanism and a fourth diamond-shaped amplifying mechanism having similar functions to prevent the piezoelectric ceramic driver from being subjected to shear force.

[0025] The various configurations of the compliant unit are designed with rigid parts to ensure the rigidity of the base and provide rigid support for other flexible parts.

[0026] The sides of the various configurations of the compliant unit are designed with pre-tightening screw mounting holes, and the pre-tightening of the piezoelectric ceramic is adjusted by the pre-tightening screw torque to change the input force.

[0027] Compared with the prior art, the present invention can at least achieve the following beneficial effects:

[0028] (1) The compliance unit proposed in the present invention can be designed as a first compliance unit, a second compliance unit, a third compliance unit, and a fourth compliance unit configuration. The four configurations can have the same installation size. By replacing the four compliance unit structures, the stick-slip positioning platform of the same design can be driven. Different driving effects can be achieved by installing different compliance units in the same installation method and installation space.

[0029] (2) The first compliant unit, the second compliant unit, the third compliant unit, and the fourth compliant unit proposed in the present invention have different stiffness characteristics. By comparing the driving characteristics of the four compliant unit structures, the influence of the compliant unit structures with different stiffness characteristics on the stick-slip motion form can be analyzed;

[0030] (3) The compliant unit structure proposed in the present invention is driven by the first card slot, the second card slot, the third card slot or the fourth card slot with similar structure and the same function to drive the friction material, and can generate stick-slip motion through sawtooth wave drive. The friction is consumed on the friction material rather than on the integral material of the compliant unit. By selecting the friction material, the service life can be improved, and the worn friction material can be replaced to avoid directly replacing the entire compliant unit after wear, thereby reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning provided by an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of the structure of the first compliance unit in the stiffness-optimized compliance drive mechanism for piezoelectric stick-slip positioning in an embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the structure of the second compliance unit in the stiffness-optimized compliance drive mechanism for piezoelectric stick-slip positioning in an embodiment of the present invention;

[0034] Figure 4 Schematic diagram of the structure of the third compliance unit in the stiffness-optimized compliance drive mechanism for piezoelectric stick-slip positioning in an embodiment of the present invention;

[0035] Figure 5 Schematic diagram of the structure of the fourth compliant unit in the stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The configuration proposed in the present invention provides embodiments 1 to 4 of the overall structure of a stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning and four compliant unit structures with different physical characteristics. Other piezoelectric compliant drives can also achieve corresponding functions through this configuration and corresponding principles.

[0038] See also Figure 1 The stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning proposed in the present invention includes a pretightening member, a piezoelectric ceramic 2 and a compliant unit 3, wherein the pretightening member is a screw, defined as a pretightening screw 1, and a slot is provided on the compliant unit 3, in which a friction material can be embedded, and a threaded hole is provided on the side of the compliant unit 3. The piezoelectric ceramic 2 is assembled to the threaded hole of the compliant unit 3 by the pretightening screw 1, and the pretightening of the piezoelectric ceramic 2 is achieved by adjusting the torque of the pretightening screw 1.

[0039] The input stiffness and output stiffness can be changed by changing the internal geometric features of the compliance unit 3. The compliance unit 3 can be designed as any one of the first compliance unit, the second compliance unit, the third compliance unit, and the fourth compliance unit structure, and the slots on the corresponding compliance units are defined as the first slot, the second slot 16, the third slot 24, and the fourth slot 31.

[0040] The stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning uses the stick-slip drive principle to achieve movement. The elongation of the piezoelectric ceramic 2 is positively correlated with the voltage. The voltage signal of the piezoelectric ceramic 2 is a sawtooth wave input, which is converted into a motion output at the first card slot 6 or the second card slot 16 or the third card slot 24 or the fourth card slot 31 through the physical structure of the compliance unit 3 itself, so that the first card slot 6 or the second card slot 16 or the third card slot 24 or the fourth card slot 31 drives the friction material to move slowly in a certain direction in the horizontal direction and then quickly retreat. When the sawtooth wave signal is in a state of slowly increasing, the friction material in the first card slot 6 and the external friction material have a certain friction contact and can move a certain distance in parallel in the elongation direction of the piezoelectric ceramic 2. Static friction is generated between objects (such as guide rails), and the friction material and the object in friction contact move together along the elongation direction of the piezoelectric ceramic 2; when the sawtooth wave signal is in a rapid decrease, the first slot 6 or the second slot 16 or the third slot 24 or the fourth slot 31 drives the friction material to move rapidly. Due to the inertia of the object in friction contact itself, relative motion and a certain dynamic friction are generated between the friction material in the first slot 6 or the second slot 16 or the third slot 24 or the fourth slot 31 and the object in friction contact. The friction material drives the object in friction contact to retreat along the shortening direction of the piezoelectric ceramic 2 for a displacement smaller than the forward motion. The output of linear motion is achieved through the periodic change of the sawtooth wave signal and the stick-slip motion principle.

[0041] Among them, the final output part of the driving mechanism is a card slot, and different output effects are achieved through stick-slip motion by embedding friction materials with different properties in the card slot. For example, the card slot is embedded with zirconia ceramic friction material, and the low friction coefficient and high wear resistance of zirconia ceramic itself can provide a preload force with a large variable space while achieving the output force at the card slot, reducing the difficulty of adjustment; for another example, the card slot is embedded with bearing steel friction material, and the bearing steel friction material is welded and fixed in the card slot, which can improve the thermal stability of the output stick-slip motion, so that the piezoelectric stick-slip positioning based on the compliance unit 3 has low thermal decay, and reduces the thermal decay of the friction material caused by long-term friction heating.

[0042] Example 1

[0043] See also Figure 2 , the compliance unit 3 can become the configuration of the first compliance unit through the design of physical characteristics.

[0044] The first compliant unit includes a first fixed rigid part 12, a first rhombus amplifying mechanism 4, a first movable rigid part 5, a first rotationally compliant hinge 11, a second movable rigid part 8, a parallel contact lever 7, and a lever-type amplifying mechanism rotating hinge 10. The rigidity of the base can be ensured by setting the rigid part, and the output force and output displacement of the piezoelectric ceramic 2 can be flexibly amplified and reduced by the first rhombus amplifying mechanism 4, the first rotationally compliant hinge 11, the parallel contact lever 7, and the lever-type amplifying mechanism rotating hinge 10, and the transmission direction of the force and displacement can be changed by the first movable rigid part 5 and the second movable rigid part 8.

[0045] Among them, the first fixed rigid part 12 is the base of the compliant unit 3, and it is regarded as a rigid body because of its small deformation. A first rhombus amplifying mechanism 4 symmetrically arranged in the upper and lower parts is arranged on the left side of the first fixed rigid part 12, and the first rhombus amplifying mechanism 4 is connected to the first movable rigid part 5. The piezoelectric ceramic 2 is assembled between the first movable rigid part 5 and the first fixed rigid part 12 and in the first rhombus amplifying mechanism 4 symmetrically arranged in the upper and lower parts. The left end of the piezoelectric ceramic 2 supports the first fixed rigid part 12, and the right end of the piezoelectric ceramic 2 supports the left end of the first movable rigid part 5. The elongation of the piezoelectric ceramic 2 will cause the first rhombus amplifying mechanism 4 to deform, thereby storing elastic energy. The existence of the first rhombus amplifying mechanism 4 prevents the piezoelectric ceramic 2 from being subjected to shear force. The first movable rigid part 5 is connected to the second movable rigid part 8 on the right side through the first rotary compliant hinge 11, and the first movable rigid part 5 is flexibly connected to the second movable rigid part 8 through the first rotary compliant hinge 11. The upper part of the second movable rigid part 8 is connected to the first card slot 6 through the parallel contact lever 7 to optimize the rigidity of the first card slot 6 in the vertical direction. Friction material is arranged in the first card slot 6. The lower part of the second movable rigid part 8 is connected to the first fixed rigid part 12 through the lever-type amplification mechanism rotating hinge 10. The lever-type amplification mechanism rotating hinge 10 generates relative rotational motion, thereby realizing amplified output at the first card slot 6.

[0046] The stick-slip driving method is that the voltage signal of the piezoelectric ceramic 2 is a sawtooth wave input, and the sawtooth wave signal causes the first slot 6 to drive the friction material to move slowly in a certain direction in the horizontal direction and then quickly retreat, which is converted into an output at the first slot 6 through the physical structure of the first compliance unit itself, and generates a stick-slip motion with constantly changing sliding friction and static friction on an object in friction contact parallel to the first slot 6, thereby realizing the output of linear motion.

[0047] Example 2

[0048] See also Figure 3The compliant unit 3 can be designed into the configuration of the second compliant unit by changing the physical characteristics. The driving mode and the preload adjustment mode of the second compliant unit are the same as those of the first compliant unit, and the same space for embedding the piezoelectric ceramic 2 is provided between the second fixed rigid part 19 and the third movable rigid part 14. The second compliant unit includes a second fixed rigid part 19, a second diamond-shaped amplifying mechanism 13, a third movable rigid part 14, a first flexible contact cantilever beam 15, a parallelogram preload compliant beam 17 and a preload adjustment seat 18.

[0049] The output force and output displacement of the piezoelectric ceramic 2 are flexibly amplified and reduced through the second diamond-shaped amplifying mechanism 13 , the first flexible contact cantilever beam 15 , and the parallelogram preloaded compliant beam 17 , and the transmission direction of the force and displacement is changed through the third movable rigid part 14 .

[0050] Among them, a second diamond-shaped amplifying mechanism 13 symmetrically arranged in the upper and lower parts is arranged on the left side of the second fixed rigid part 19, the second diamond-shaped amplifying mechanism 13 is connected to the third movable rigid part 14, the piezoelectric ceramic 2 is located between the second fixed rigid part 19 and the third movable rigid part 14 and is located in the second diamond-shaped amplifying mechanism 13, the left side of the piezoelectric ceramic 2 supports the second fixed rigid part 19, and the right side supports the left end of the third movable rigid part 14. The design of the second diamond-shaped amplifying mechanism 13 prevents the piezoelectric ceramic 2 from being subjected to shear force and can store its elastic energy through elastic deformation, and the design of the second fixed rigid part 19 can ensure the rigidity of the second compliant unit matrix.

[0051] The third movable rigid part 14 is connected to the second slot 16 through the first flexible contact cantilever beam 15. The second slot 16 is provided with friction material. An inclined parallelogram preloaded compliant beam 17 is provided in the space below the second slot 16 and facing the second fixed rigid part 19. The parallelogram preloaded compliant beam 17 includes two mutually parallel support beams. The support beam on the right side of the parallelogram preloaded compliant beam 17 is connected to the second fixed rigid part 19, and the support beam on the left side of the parallelogram preloaded compliant beam 17 is connected to the preload force adjustment seat 18.

[0052] The second compliant unit changes the input stiffness, output stiffness, amplification ratio and other output characteristics at the second slot 16 through the cooperation of the second diamond-shaped amplification mechanism 13, the first flexible contact guide beam 15 and the parallelogram pre-tightening compliant beam 17. The first flexible contact guide beam 15 provides weak stiffness contact between the output and the input, reducing the influence of the input stiffness. The parallelogram pre-tightening compliant beam 17 compensates for the weakening of the output stiffness through the parallel rod part, improving the pre-tightening displacement. It can be understood that the method of the parallelogram pre-tightening compliant beam 17 is not limited to Figure 3 The structure of two supporting beams in parallel shown in the figure does not change Figure 3Under the supporting beam on the left side of the parallelogram preloaded compliant beam 17 shown, by changing the supporting beam on the right side of the parallelogram preloaded compliant beam 17, that is, the number of supporting beams located on the right side of the supporting beam on the left side of the parallelogram preloaded compliant beam 17 and connected to the second slot 16 and the second fixed rigid part 19, the input and output stiffness can be changed approximately proportionally.

[0053] See also Figure 3 The second compliant unit is designed with a preload adjustment seat 18 between the second fixed rigid part 19 and the left support beam of the parallelogram preload compliant beam 17. A screw is screwed in from bottom to top through a threaded hole (i.e., a preload hole) opened on the second rigid part 19 and located directly below the preload adjustment seat 18. The screw passes through the threaded hole and abuts against the preload adjustment seat 18. By tightening the screw, the preload adjustment seat 18 moves axially toward the screw, thereby causing flexible deformation of the parallelogram preload compliant beam 17 and the first flexible contact guide beam 15. The vertical displacement at the second slot 16 can be indirectly adjusted through the screw.

[0054] Example 3

[0055] See also Figure 4 The compliance unit 3 can be designed into the configuration of a third compliance unit by changing its physical characteristics. The driving mode and the preload adjustment mode of the third compliance unit are the same as those of the first compliance unit.

[0056] The third compliant unit includes a third fixed rigid part 27, a third diamond-shaped amplifying mechanism 20, a fourth movable rigid part 21, a second flexible contact guide beam 22, a fifth movable rigid part 23, a vertical preloaded compliant beam 25, and a horizontal preloaded compliant beam 26. The output force and output displacement of the piezoelectric ceramic 2 are flexibly amplified and reduced by the third diamond-shaped amplifying mechanism 20, the second flexible contact guide beam 22, the vertical preloaded compliant beam 25, and the horizontal preloaded compliant beam 26, and the transmission direction of the force and displacement is changed by the fourth movable rigid part 21 and the fifth movable rigid part 23.

[0057] See also Figure 4, a third rhombus amplifying mechanism 20 symmetrically arranged in the upper and lower parts of the third fixed rigid part 27 of the third compliant unit is provided, the third rhombus amplifying mechanism 20 is connected to the fourth movable rigid part 21, the piezoelectric ceramic 2 is located between the third fixed rigid part 27 and the fourth movable rigid part 21 and is located in the third rhombus amplifying mechanism 20, the piezoelectric ceramic 2 supports the third fixed rigid part 27 on the left side and supports the left end of the fourth movable rigid part 21 on the right side. The design of the third rhombus amplifying mechanism 20 prevents the piezoelectric ceramic 2 from being subjected to shear force and can store its elastic energy through elastic deformation, thereby improving the input stiffness. The fourth movable rigid part 21 is connected to the fifth movable rigid part 23 through the second flexible contact guide beam 22, the fifth movable rigid part 23 is rigidly connected to the third card slot 24, the third card slot 24 is embedded with friction material, the second flexible contact guide beam 22 performs flexible transmission between the input and output parts, thereby improving the output stiffness of the third compliant unit in the vertical direction and making the amplification ratio of the third compliant unit close to 1.

[0058] In this embodiment, the third diamond-shaped amplifying mechanism 20 is provided to prevent the piezoelectric ceramic 2 from being subjected to shear force. The third fixed rigid part 27 is provided to ensure the rigidity of the third compliant unit base.

[0059] See also Figure 4 , the vertical preloaded compliant beam 25 and the horizontal preloaded compliant beam 26 are perpendicular to each other and connected in series, the leftmost part of the vertical preloaded compliant beam 25 is connected to the fifth movable rigid part 23, and the rightmost part of the vertical preloaded compliant beam 25 is connected to the third fixed rigid part 27. The vertical preloaded compliant beam 25 generates deformation displacement in the left and right directions of the third compliant unit, affecting the input stiffness; the horizontal preloaded compliant beam 26 generates deformation displacement in the up and down directions of the third compliant unit, affecting the output stiffness and providing preloaded displacement, wherein the input stiffness can be increased or decreased by changing the span, width, and number of parallel beams of the vertical preloaded compliant beam 25. The horizontal preloaded compliant beam 26 is perpendicular to the pressure direction of the friction material on the third slot 24, and the output stiffness can be increased or decreased by changing the span, width, and number of parallel beams of the horizontal preloaded compliant beam 26.

[0060] Example 4

[0061] See also Figure 5 The compliance unit 3 can be designed into the configuration of a fourth compliance unit by changing its physical characteristics. The driving mode and the preload adjustment mode of the fourth compliance unit are the same as those of the first compliance unit.

[0062] The fourth compliant unit includes a fourth fixed rigid part 33, a fourth diamond-shaped amplifying mechanism 28, a sixth movable rigid part 29, a third flexible contact guide beam 30, a fourth slot 31 and a "Z"-shaped preloaded compliant beam 32. The output force and output displacement of the piezoelectric ceramic 2 are flexibly amplified and reduced by the fourth diamond-shaped amplifying mechanism 28, the sixth movable rigid part 29, the third flexible contact guide beam 30 and the "Z"-shaped preloaded compliant beam 32, and the transmission direction of the force and displacement is changed by the sixth movable rigid part 29.

[0063] See also Figure 5 , a fourth rhombus amplifying mechanism 28 symmetrically arranged in the upper and lower parts is arranged on the left part of the fourth fixed rigid part 33 of the fourth compliant unit, the fourth rhombus amplifying mechanism 28 is connected to the sixth movable rigid part 29, the piezoelectric ceramic 2 is located between the fourth fixed rigid part 33 and the sixth movable rigid part 29 and is located in the fourth rhombus amplifying mechanism 28, the piezoelectric ceramic 2 supports the fourth fixed rigid part 33 on the left side and the left end of the sixth movable rigid part 29 on the right side. The arrangement of the fourth rhombus amplifying mechanism 28 prevents the piezoelectric ceramic 2 from being subjected to shear force and can store its elastic energy through elastic deformation, thereby improving the input stiffness. Between the right side of the sixth movable rigid part 29 and the right side structure of the fourth fixed rigid part 33, the third flexible contact guide beam 30, the fourth card slot 31 and the "Z"-shaped pre-tightening compliant beam 32 are connected in series in sequence. The fourth card slot 2 is embedded with friction material.

[0064] In this embodiment, the third flexible contact guide beam 30 mainly affects the input stiffness of the portion from the sixth movable rigid portion 29 to the fourth slot 31, and also indirectly affects the amplification ratio. The beam direction in the "Z"-shaped preloaded compliant beam 32 is at a certain angle to the input force direction of the piezoelectric ceramic 2 and the pressure direction of the friction material of the fourth slot 31. By changing these angles, the purpose of adjusting the input stiffness and output stiffness in a certain proportion by changing the internal beam span and width of the "Z"-shaped preloaded compliant beam 32 at a certain angle can be achieved.

[0065] See also Figure 5 The fourth diamond-shaped amplifying mechanism 23 is provided to prevent the piezoelectric ceramic 2 from being subjected to shear force. The fourth rigid portion 26 is designed to ensure the rigidity of the fourth compliant unit matrix.

[0066] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A stiffness-optimized compliant drive mechanism for piezoelectric stick-slip positioning, characterized in that: It includes a compliance unit, a pre-tightening member and a piezoelectric ceramic. The compliance unit is provided with a slot, a friction material is provided in the slot, the piezoelectric ceramic is arranged on the compliance unit, and the piezoelectric ceramic and the compliance unit are connected through the pre-tightening member, and the piezoelectric ceramic is pre-tightened by adjusting the torque of the pre-tightening member.

2. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 1, characterized in that: The elongation of the piezoelectric ceramic is positively correlated with the voltage. When working, the voltage signal of the piezoelectric ceramic is a sawtooth wave input, which is converted into an output at the slot through the physical structure of the compliance unit itself, so that the slot drives the friction material to move slowly in a certain direction in the horizontal direction and then quickly retreat. When the sawtooth wave signal is in a slow increase, static friction is generated between the friction material of the slot and the object in friction contact parallel to it, and the friction material and the object in friction contact move together in the elongation direction of the piezoelectric ceramic; when the sawtooth wave signal is in a fast decrease, the slot drives the friction material to move quickly, and the friction material drives the object in friction contact to retreat in the shortening direction of the piezoelectric ceramic for a displacement smaller than the forward motion. The output of linear motion is achieved through the periodic change of the sawtooth wave signal and the stick-slip motion principle.

3. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 1, characterized in that: The compliance unit is a first compliance unit, and the first compliance unit includes a first fixed rigid part and a first diamond-shaped amplifying mechanism located on the first fixed rigid part, a first movable rigid part, a first rotating compliance hinge, a second movable rigid part, a parallel contact lever and a lever-type amplifying mechanism rotating hinge, and the card slot provided on the first compliance unit is a first card slot, The first diamond-shaped amplifying mechanism, the first movable rigid part, the first rotationally flexible hinge and the second movable rigid part are connected in sequence. The piezoelectric ceramic is arranged in the first diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the first diamond-shaped amplifying mechanism to deform to store elastic energy. The second movable rigid part is connected to the first card slot through a parallel contact lever at the top and is connected to the first fixed rigid part through a lever-type amplifying mechanism rotation hinge at the bottom.

4. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 1, characterized in that: The compliant unit is a second compliant unit, which includes a second fixed rigid part and a second rhombus amplifying mechanism located on the second fixed rigid part, a third movable rigid part, a first flexible contact cantilever beam, a parallelogram preloaded compliant beam and a preload force adjustment seat, and the slot provided on the second compliant unit is a second slot. The second diamond-shaped amplifying mechanism, the third movable rigid part, the first flexible contact cantilever beam and the second slot are connected in sequence, the piezoelectric ceramic is arranged in the second diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the second diamond-shaped amplifying mechanism to deform to store elastic energy; The parallelogram preloaded compliant beam comprises at least two support beams, one of which is connected to the second slot and the second fixed rigid part, the other support beam is provided with the preload adjustment seat, and a preload hole is provided on the second fixed rigid part and at a position opposite to the preload adjustment seat.

5. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 4, characterized in that: The input and output stiffnesses are adjusted by adjusting the number of support beams connecting the second slot and the second fixed rigid portion.

6. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 1, characterized in that: The compliant unit is a third compliant unit, which includes a third fixed rigid part and a third diamond-shaped amplifying mechanism located on the third fixed rigid part, a fourth movable rigid part, a second flexible contact guide beam, a fifth movable rigid part, a vertical pre-tightening compliant beam and a horizontal pre-tightening compliant beam, and the slot provided on the third compliant unit is a third slot. The third diamond-shaped amplifying mechanism, the fourth movable rigid part, the second flexible contact guide beam, the fifth movable rigid part and the third slot are connected in sequence, the piezoelectric ceramic is arranged in the third diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the third diamond-shaped amplifying mechanism to deform to store elastic energy; The vertical pre-tensioned compliant beam and the horizontal pre-tensioned compliant beam are perpendicular to each other and connected in series. The vertical pre-tensioned compliant beam is connected to both the fifth movable rigid part and the third fixed rigid part. The vertical pre-tensioned compliant beam is used to generate deformation displacement in the left and right directions of the third compliant unit, and the horizontal pre-tensioned compliant beam is used to generate deformation displacement in the up and down directions of the third compliant unit.

7. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 6, characterized in that: The increase or decrease of input stiffness is achieved by changing the span, width and number of parallel beams of the vertical preloaded compliant beam.

8. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to any one of claims 6-7, characterized in that: The output stiffness can be increased or decreased by changing the span, width and number of parallel beams of the horizontal preloaded compliant beam.

9. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 1, characterized in that: The compliant unit is a fourth compliant unit, which includes a fourth fixed rigid part and a fourth diamond-shaped amplifying mechanism located on the fourth fixed rigid part, a sixth movable rigid part, a third flexible contact guide beam, a fourth clamping slot and a "Z"-shaped pre-tightening compliant beam, and the clamping slot provided on the fourth compliant unit is a fourth clamping slot. The fourth diamond-shaped amplifying mechanism, the sixth movable rigid part, the third flexible contact guide beam, the fourth slot and the "Z"-shaped pre-tightening compliant beam are connected in sequence, and the end of the "Z"-shaped pre-tightening compliant beam is connected to the fourth fixed rigid part. The piezoelectric ceramic is arranged in the fourth diamond-shaped amplifying mechanism and the elongation of the piezoelectric ceramic can cause the fourth diamond-shaped amplifying mechanism to deform to store elastic energy, wherein the beam direction in the "Z"-shaped pre-tightening compliant beam is at a certain angle to the input force direction of the piezoelectric ceramic and the pressure direction of the friction material of the fourth slot.

10. A stiffness optimized compliant drive mechanism for piezoelectric stick-slip positioning according to claim 9, characterized in that: The input stiffness and the output stiffness are adjusted by changing the angle between the beam direction in the "Z"-shaped preloaded compliant beam and the input force direction of the piezoelectric ceramic and the pressure direction of the friction material on the fourth slot.

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