A centralized and flexible three-stage displacement amplification mechanism

Abstract

The present invention relates to a centralized, compliant, three-stage displacement amplification mechanism, comprising a base, an input end beam, an output end concentrated mass, and a flexible hinge. A lever mechanism, a Scott-Russell mechanism, and an arc mechanism are provided on both sides of the input end beam. The input end beam is connected to the input end of the lever mechanism via a flexible hinge. The lever mechanism is connected to the base, and the output end of the lever mechanism is connected to the Scott-Russell mechanism via a flexible hinge. The Scott-Russell mechanism comprises a large mass block and a small mass block, the base and the large mass block are respectively connected to the small mass block via flexible hinges, the output end of the lever mechanism is connected to the input end of the large mass block via a flexible hinge, the output end of the large mass block is fixedly connected to one end of the arc mechanism, and the other end of the arc mechanism is fixedly connected to the output end concentrated mass. The mechanism has suitable output stiffness, fast dynamic response, and uniform stress distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of compliant mechanisms, in particular to a centralized compliant three-stage displacement amplification mechanism. Background Art

[0002] Compliant mechanisms transmit force and energy through elastic deformation, thereby achieving partial or full motion. Compliant mechanisms can be categorized as fully compliant or partially compliant, depending on whether they include rigid kinematic pairs. Fully compliant mechanisms, lacking traditional rigid kinematic pairs, can be further categorized as distributed or concentrated compliance. In the former, elastic deformation is generally distributed relatively evenly throughout the entire mechanism, while in the latter, elastic deformation typically occurs in the flexible joint region, primarily at the flexible hinge.

[0003] Compared to traditional rigid mechanisms, compliant mechanisms lack rigid kinematic pairs, resulting in the following advantages: 1. A small number of components, requiring no assembly, allows for miniaturized and integrated manufacturing. 2. The absence of rigid kinematic pairs makes compliant mechanisms lightweight, facilitating their own miniaturization, lightweighting, and mass production in factories. 3. The absence of friction, wear, and transmission clearance, resulting in a small dead stroke, allows for high-precision motion. 4. No lubricant is required, preventing contamination, and the mechanism is noiseless, with a long lifespan and low maintenance costs. 5. Variable stiffness, significant energy storage and conversion characteristics, and inherent return reaction force are achieved. 6. Compliant mechanisms can be compatible with a variety of drive modes, such as piezoelectric ceramic drives, stick-slip drives, and ultrasonic motor drives. These advantages have led to their promising applications in many engineering fields, including precision engineering, robotics, micro-electromechanical systems, sensors, intelligent structures, and bioengineering.

[0004] Displacement-amplifying compliant mechanisms are a very common and important type of compliant mechanism, often used in combination with piezoelectric actuators to amplify their tiny output displacements. They play an indispensable role in applications such as micro-nano manipulation, precision engineering, and microelectromechanical systems. Traditional displacement-amplifying mechanisms include bridge mechanisms, Scott-Russell mechanisms, and lever mechanisms, and have been widely used to amplify the displacement or force of precision actuators and sensors. These structures are simple, but suffer from low displacement amplification efficiency and need to improve output performance. Numerous derivative structures have been designed by improving or combining these classic types. In a multi-stage displacement-amplifying compliant mechanism, the output displacement of the previous stage serves as the input displacement of the next stage, and the output force of the previous stage serves as the driving force for the next stage. If the ratio of the output stiffness of the previous stage to the input stiffness of the next stage is large, the composite displacement amplification ratio is large. This suggests that combining a compliant amplifying module with high output stiffness with a compliant amplifying module with low input stiffness can improve the output displacement of a multi-stage displacement-amplifying compliant mechanism. Although there are many multi-stage displacement amplification compliant mechanisms that can achieve large strokes, the structural compactness, displacement amplification efficiency and high dynamic bandwidth of the compliant mechanism itself still need to be improved.

[0005] The prior art discloses a paper: Ling M, Yuan L, Luo Z, et al. Enhancing dynamic bandwidth of amplified piezoelectric actuators by a hybrid lever and bridge-type compliant mechanism [J]. Actuators, 2022, 11(5): 134. This paper combines a lever-type compliant mechanism and a half-bridge compliant mechanism to design a compact two-stage displacement amplification mechanism, achieving a good balance between displacement amplification ratio and dynamic bandwidth. The static and dynamic performance of the two-stage displacement amplification mechanism was predicted based on a two-port dynamic stiffness model, and the theoretical model was simulated and experimentally verified. Although it has a high frequency response and relatively large output stiffness, it is only a two-stage displacement amplification, resulting in a low displacement amplification ratio and cannot adapt to many application scenarios with high stroke requirements.

[0006] Therefore, pursuing high bandwidth, large displacement and high displacement amplification efficiency in a compact space remains a challenging problem. Since bandwidth and displacement amplification ratio are mutually exclusive, how to balance these two static and dynamic performances is also full of challenges in engineering applications. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a centralized flexible three-stage displacement amplification mechanism with high bandwidth, large displacement and high displacement amplification efficiency as well as appropriate output stiffness.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A centralized compliant three-stage displacement amplification mechanism, comprising a base, an input end beam, an output end centralized mass and a plurality of flexible hinges;

[0010] Both sides of the input end beam are equipped with lever mechanism, Scott-Russell mechanism and arc mechanism;

[0011] One end of the input end beam is connected to the input end of the lever mechanism through a flexible hinge;

[0012] The fulcrum end of the lever mechanism is connected to the base through a flexible hinge, and the output end of the lever mechanism is connected to the Scott-Russell mechanism through a flexible hinge;

[0013] The Scott-Russell mechanism comprises a large mass block and a small mass block. The base and the large mass block are respectively connected to the small mass block via flexible hinges. The output end of the lever mechanism is connected to the input end of the large mass block via a flexible hinge. The output end of the large mass block is fixed to one end of the arc mechanism.

[0014] The other end of the arc-shaped mechanism is fixedly connected to the output end to concentrate the mass.

[0015] Furthermore, a flexible connecting beam is provided between the input end beam and the lever mechanism, and both ends of the flexible connecting beam are respectively connected to the input end beam and the lever mechanism through flexible hinges, and the flexible connecting beam is perpendicular to the input end beam and the lever mechanism.

[0016] Furthermore, the input end beam is located in the middle of the base, a driving source is provided in the base, and the input end beam is correspondingly provided between the driving source and the output end concentrated mass.

[0017] Furthermore, the driving source is a piezoelectric stack driver.

[0018] Furthermore, the flexible hinge is a red blood cell flexible hinge.

[0019] Furthermore, the base is provided with a mounting through hole.

[0020] Furthermore, the centralized flexible three-stage displacement amplification mechanism is an integrated structure.

[0021] Furthermore, the centralized compliant three-stage displacement amplification mechanism is made of aluminum alloy material through wire cutting.

[0022] In general, the present invention has the following advantages:

[0023] The input displacement or force is transmitted to the input end of the lever mechanism via the input end beam, which serves as the first-stage amplification mechanism. The output end of the lever mechanism then drives the Scott-Russell mechanism, which serves as the second-stage amplification mechanism. The output end of the Scott-Russell mechanism then drives the arc mechanism, which then concentrates mass at the output end for output, serving as the third-stage amplification mechanism. This three-stage amplification achieves high bandwidth, large displacement, and high displacement amplification efficiency. Because the output end of the Scott-Russell mechanism's large mass block is fixed to one end of the arc mechanism, it provides suitable output stiffness, resulting in fast dynamic response and uniform stress distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the three-dimensional structure of the centralized compliant three-stage displacement amplification mechanism of this embodiment.

[0025] Figure 2 Schematic diagram of the planar structure of the centralized compliant three-stage displacement amplification mechanism of this embodiment.

[0026] Figure 3 Schematic diagram of the three-dimensional structure of the red blood cell flexible hinge of this embodiment.

[0027] Figure 4 Schematic diagram of the planar structure of the red blood cell flexible hinge of this embodiment.

[0028] Figure 5 Schematic diagram comparing the flexibility and precision of the red blood cell flexible hinge in the lateral direction compared to the elliptical and circular flexible hinges.

[0029] Figure 6 Schematic diagram comparing the flexibility and accuracy of the red blood cell flexible hinge in the rotational direction relative to the elliptical and circular flexible hinges.

[0030] Figure 7 Schematic diagram comparing the maximum stress of the red blood cell flexible hinge with that of the elliptical and circular flexible hinges under the same lateral deflection.

[0031] In the picture:

[0032] 1-Input end beam, 2-Flexible connecting beam, 3-Lever mechanism, 4-Scott-Russell mechanism, 5-Red blood cell flexible hinge, 51-Quadratic Bezier curve, 6-Output end concentrated mass, 7-Arc mechanism, 8-Base, 9-Through hole, 10-Square slot. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below.

[0034] like Figure 1 、 Figure 2 As shown, a centralized flexible three-stage displacement amplification mechanism includes a base 8, an input end beam 1, an output end centralized mass 6, two flexible connecting beams 2, multiple red blood cell flexible hinges 5, a double-arm semi-elliptical mechanism, a symmetrical lever device and a symmetrical Scott-Russell device.

[0035] The input end beam 1 is located in the middle of the base 8 .

[0036] The input end beam 1 and the flexible connecting beam 2 are connected by a red cell flexible hinge 5. The flexible connecting beam 2 transmits the displacement or force of the input end beam 1 to the lever mechanism 3. Because the flexible connecting beam 2 connected to the input end beam 1 serves as a guide, the use of guide beams is avoided, reducing the number of flexible joints.

[0037] The flexible connecting beam 2 is connected to the input end of the lever mechanism 3 via the red cell flexible hinge 5; the flexible connecting beam 2 is perpendicular to the input end beam 1 and the lever mechanism 3. The two lever mechanisms 3 are located on both sides of the input end beam 1, forming a symmetrical lever device.

[0038] The fulcrum end of the lever mechanism 3 is connected to the base 8 through the red cell flexible hinge 5; the output end of the lever mechanism 3 is connected to the input end of the Scott-Russell mechanism 4 through the red cell flexible hinge 5; the Scott-Russell mechanism 4 is provided with a large mass block and a small mass block, the base 8 and the large mass block are respectively connected to the small mass block through the red cell flexible hinge 5, the output end of the lever mechanism 3 is connected to the input end of the large mass block through the red cell flexible hinge 5, and the output end of the large mass block is fixed to one end of the double-arm semi-elliptical mechanism; the two Scott-Russell mechanisms 4 are respectively located on both sides of the input end beam 1 to form a symmetrical Scott-Russell device.

[0039] Two arc-shaped mechanisms 7 are symmetrically positioned on either side of the input beam 1. These two arc-shaped mechanisms 7 combine to form a two-arm semi-elliptical mechanism. The output end of the large mass block is fixed to one end of the arc-shaped mechanism 7, while the other end of the arc-shaped mechanism 7 is fixed to the output-end concentrated mass 6. The output-end concentrated mass 6 is positioned corresponding to the middle of the input beam 1.

[0040] In this embodiment, the entire centralized, compliant, three-stage displacement amplification mechanism is fabricated from a single piece of aluminum alloy using wire cutting. The two mechanisms are bilaterally symmetrical around the input beam 1, resulting in minimal parasitic errors. While maintaining a large displacement amplification ratio and high displacement amplification efficiency, they also achieve high output stiffness and a high natural frequency. This simplifies mechanism control and operation, effectively ensuring the accuracy of the displacement amplification mechanism. Therefore, this mechanism has promising applications in fields such as precision engineering and micro-electromechanical systems.

[0041] A square slot 10 is defined along the central axis of symmetry on base 8 for mounting a piezoelectric stack actuator. One end of the piezoelectric stack actuator is secured to base 8, shielding the centralized, compliant, three-stage displacement amplification mechanism from the inertial motion of the piezoelectric stack actuator. Base 8 has a through-hole 9, which is bolted to a threaded hole on the optical platform. Given a given input drive, the centralized, compliant, three-stage displacement amplification mechanism can release both output force and displacement in the same direction at the output end, achieving single-degree-of-freedom motion.

[0042] The present invention obtains a centralized compliant three-stage displacement amplification mechanism through three-stage amplification of a symmetrical lever device, a symmetrical Scott-Russell device and a double-arm semi-elliptical mechanism, which ensures high bandwidth, large displacement and appropriate output stiffness in a compact space.

[0043] In existing multi-stage displacement amplification mechanisms, the final stage typically uses a diamond-shaped mechanism or a bridge-type mechanism with a mass block. The former can lead to stress concentration, while the latter can reduce the natural frequency. This embodiment uses a double-arm semi-elliptical mechanism as the final stage, which ensures uniform stress distribution without reducing the natural frequency.

[0044] The rotational accuracy and stress distribution of flexible hinges directly impact the fatigue strength and service life of compliant mechanisms. Finding a flexible hinge with high rotational accuracy and uniform stress distribution is a goal of both academia and engineering. Existing flexible hinges used in multi-stage displacement amplification mechanisms are typically circular, elliptical, straight beam, V-shaped, or other types. Each hinge offers advantages and disadvantages, presenting a difficult trade-off between flexibility, accuracy, and maximum stress.

[0045] like Figure 3 、 Figure 4 As shown, the flexible hinge used in this patent is a red blood cell flexible hinge 5. Inspired by the biconcave disk shape of red blood cells in nature, the red blood cell flexible hinge 5 is a curvature-adjustable flexible hinge obtained by biomimetic design based on a quartic Bezier curve 51 to fit the red blood cell contour curve. In this invention, it is simply referred to as the red blood cell flexible hinge 5. Both ends of the red blood cell flexible hinge 5 have smooth transitions, and the red blood cell flexible hinge 5 itself has the characteristic of double curvature.

[0046] like Figure 5-Figure 7 As shown, the red blood cell flexible hinge 5 has the advantages of high rotation accuracy and uniform stress distribution compared to other types of flexible hinges, meeting the performance design requirements of compact space in the fields of precision engineering and micro-electromechanical systems.

[0047] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A centralized compliant three-stage displacement amplification mechanism, characterized by: It includes a base, an input end beam, an output end concentrated mass and a plurality of flexible hinges; Both sides of the input end beam are equipped with lever mechanism, Scott-Russell mechanism and arc mechanism; One end of the input end beam is connected to the input end of the lever mechanism through a flexible hinge; The fulcrum end of the lever mechanism is connected to the base through a flexible hinge, and the output end of the lever mechanism is connected to the Scott-Russell mechanism through a flexible hinge; The Scott-Russell mechanism comprises a large mass block and a small mass block. The base and the large mass block are respectively connected to the small mass block via flexible hinges. The output end of the lever mechanism is connected to the input end of the large mass block via a flexible hinge. The output end of the large mass block is fixed to one end of the arc mechanism. The other end of the arc-shaped mechanism is fixedly connected to the output end to concentrate the mass; A flexible connecting beam is provided between the input end beam and the lever-type mechanism, and both ends of the flexible connecting beam are respectively connected to the input end beam and the lever-type mechanism through flexible hinges, and the flexible connecting beam is perpendicular to the input end beam and the lever-type mechanism; The flexible hinge is a red blood cell flexible hinge.

2. The centralized compliant three-stage displacement amplification mechanism according to claim 1, characterized in that: The input end beam is located in the middle of the base, a driving source is provided in the base, and the input end beam is correspondingly provided between the driving source and the output end concentrated mass.

3. The centralized compliant three-stage displacement amplification mechanism according to claim 2, characterized in that: The driving source is a piezoelectric stack driver.

4. The centralized compliant three-stage displacement amplification mechanism according to claim 1, characterized in that: The base is provided with a mounting through hole.

5. The centralized compliant three-stage displacement amplification mechanism according to claim 1, characterized in that: The three-stage displacement amplification and compliance mechanism is an integrated structure.

6. The centralized compliant three-stage displacement amplification mechanism according to claim 1, characterized in that: The three-stage displacement amplification compliance mechanism is made of aluminum alloy material through wire cutting.

Images