Parallel vibration isolation platform with three-dimensional zero-stiffness characteristics

Abstract

The application discloses a three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics, which comprises a static platform, a dynamic platform and three PRRR branches; the PRRR branch comprises a support frame, a sliding frame, a first connecting rod and a second connecting rod, the lower end of the support frame is fixed to the static platform through a base, the base is provided with a vertical spring, the upper end of the support frame is sleeved with the sliding frame, the sliding frame is slidably connected with the support frame, and the lower end and the upper end of the vertical spring are respectively fixed to the base and the sliding frame; the sliding frame, the first connecting rod, the second connecting rod and the static platform constitute first, second and third rotating pairs which are parallel to each other; the sliding frame is internally provided with a horizontal spring, one end of the horizontal spring is slidably connected with the support frame through a sliding block, and the other end of the horizontal spring is fixed to the sliding frame. The application has flexible motion characteristics, meets the space three-translational-degree-of-freedom vibration isolation requirement, and can realize the zero stiffness characteristics in X, Y and Z directions.

Description

TECHNICAL FIELD

[0001] The present application relates to a vibration isolation platform, in particular to a parallel vibration isolation platform with three-dimensional zero stiffness characteristics. BACKGROUND

[0002] In order to ensure the reliability and safety of the vehicle-mounted mobile high-end measurement and control instrument equipment, higher and higher requirements are put forward for multi-direction low-frequency vibration isolation. Designing a multi-degree-of-freedom vibration isolation device based on parallel mechanism is an effective technical solution for multi-directional vibration isolation. The combination of parallel mechanism and zero stiffness mechanism can achieve the purpose of multi-directional low-frequency vibration isolation.

[0003] Zero stiffness vibration isolator has high static and low dynamic characteristics in system stiffness, that is, when the system bears static load, the vibration isolator has relatively high system stiffness and can provide sufficient support force; when the system bears dynamic load, the vibration isolator has relatively low system stiffness, realizing low-frequency and ultra-low-frequency vibration isolation. However, most of the current nonlinear vibration isolators based on zero stiffness theory can only realize vibration reduction of specific controlled objects, and cannot meet the vibration isolation of different objects. The low stiffness displacement interval of the existing zero stiffness vibration isolator is relatively narrow, and the stiffness increases significantly with the increase of displacement, the nonlinearity is significantly enhanced, the initial vibration isolation frequency of the vibration isolator is increased, the vibration isolation frequency band is narrowed, and the low-frequency vibration isolation performance is decreased.

[0004] At the same time, there are currently various design schemes of single-degree-of-freedom zero stiffness vibration isolator, but the research on multi-degree-of-freedom, especially three-degree-of-freedom zero stiffness vibration isolator is less. Therefore, when the actual use process of the instrument is disturbed in multiple directions, the vibration isolation effect is not good. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics has a simple and compact structure, flexible motion characteristics, meets the requirements of three-dimensional translation vibration isolation, and can realize zero stiffness characteristics in X, Y and Z directions.

[0006] The three-degree-of-freedom parallel vibration isolation platform with the zero stiffness characteristic comprises a static platform, a dynamic platform and a plurality of PRRR branches.

[0007] Preferably, the support frame is provided with a sliding groove matched with the sliding block on each side, and the distance from the bottom surface of the sliding groove to the central axis of the support frame gradually decreases from top to bottom.

[0008] Preferably, the cross section of the sliding groove is isosceles trapezoidal.

[0009] Preferably, the support frame is provided with a constraint part on the inner side and the outer side, the sliding frame is provided with a groove matched with the constraint part, and the constraint part is embedded in the groove.

[0010] Preferably, the lower surface of the dynamic platform is provided with a rotating shaft mounting seat, the rotating shaft mounting seat is provided with a rotating shaft joint, the other end of the second connecting rod is provided with a first U-shaped joint matched with the rotating shaft joint, and the rotating shaft joint and the first U-shaped joint are hinged through a first hinge shaft.

[0011] Preferably, the other end of the second connecting rod is provided with a second U-shaped joint matched with the other end of the first connecting rod, and the second U-shaped joint is hinged with the other end of the first connecting rod through a second hinge shaft.

[0012] Preferably, the number of the PRRR branches is three, and the three PRRR branches are uniformly distributed relative to the center circle of the static platform.

[0013] Preferably, two horizontal springs are arranged in each sliding frame, and the two horizontal springs are symmetrically arranged relative to the support frame.

[0014] The present application has the following advantages over the prior art:

[0015] 1. The three-degree-of-freedom parallel vibration isolation platform with the zero stiffness characteristic has a simple and compact structure, flexible motion characteristics, meets the space three-translation freedom vibration isolation requirements, and can realize the zero stiffness characteristic in X, Y and Z directions.

[0016] 2、The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics of the application does not need a special spring adjusting mechanism, and the compression of the horizontal spring is adjusted by the distance between the support frame and the slider inside, so that the overall motion is more sensitive and stable compared with the vibration isolation platforms on the market.

[0017] 3、The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics of the application can adjust its performance according to the change of load, ensure stable vibration isolation effect under different load conditions, and realize vibration isolation control in different frequency intervals with accurate positioning.

[0018] 4、The traditional vibration isolation platform has only single-degree-of-freedom vibration isolation effect, and the engineering application range is small, while the application has three translational degrees of freedom, large operation space and wide engineering application range. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic view of the three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics of the application.

[0020] Figure 2 is a front view of the three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics of the application.

[0021] Figure 3 is a top view of the three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics of the application.

[0022] Figure 4 is a connection schematic view of the horizontal spring and the slider.

[0023] Figure 5 is a structural schematic view of the moving platform of the application.

[0024] Figure 6 is a structural schematic view of the support frame and the static platform of the application.

[0025] Wherein, 1 is a static platform, 2 is a moving platform, 3 is a 3-PRRR parallel mechanism, 4 is a support frame, 5 is a sliding frame, 6 is a first connecting rod, 7 is a second connecting rod, 8 is a base, 9 is a vertical spring, 10 is a first rotary pair, 11 is a second rotary pair, 12 is a third rotary pair, 13 is a horizontal spring, 14 is a slider, 15 is a sliding groove, 16 is a constraint part, 17 is a groove, 18 is a rotating shaft mounting seat, 19 is a rotating shaft joint, 20 is a first U-shaped joint, 21 is a second U-shaped joint, and 22 is an inclined rod. DETAILED DESCRIPTION

[0026] The application will be further described below in combination with the drawings and examples.

[0027] As Figures 1 to 6The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics comprises a static platform, a dynamic platform and a plurality of PRRR branches, wherein the PRRR branch comprises a support frame, a sliding frame, a first connecting rod and a second connecting rod, the lower end of the support frame is fixed to the static platform through a base, the base is provided with a vertical spring, the sliding frame is sleeved on the upper end of the support frame, and the sliding frame and the support frame are in sliding connection, the lower end and the upper end of the vertical spring are fixed to the base and the sliding frame respectively, one end of the first connecting rod is hinged to the sliding frame to form a first rotary pair, the other end of the first connecting rod is hinged to one end of the second connecting rod to form a second rotary pair, the other end of the second connecting rod is hinged to the static platform to form a third rotary pair, and the central axes of the first rotary pair, the second rotary pair and the third rotary pair are parallel to each other, and the sliding frame is provided with a horizontal spring, one end of the horizontal spring is in sliding connection with the support frame through a sliding block, and the other end of the horizontal spring is fixed to the sliding frame.

[0028] Specifically, the static platform and the dynamic platform are made of triangular plates and are arranged in parallel. The number of the PRRR branches in the embodiment is three, and the three PRRR branches are evenly distributed relative to the center circle of the static platform. That is, the central line of the static platform is taken as the center, and the circular arc angle between the adjacent two PRRR branches is 120 degrees. In this way, the static platform, the dynamic platform and the three PRRR branches form a 3-PRRR parallel mechanism. In each PRRR branch, the sliding frame slides up and down on the support frame to form a moving pair, one end of the first connecting rod is hinged to the sliding frame to form a first rotary pair, the other end of the first connecting rod is hinged to one end of the second connecting rod to form a second rotary pair, the other end of the second connecting rod is hinged to the static platform to form a third rotary pair, and the central axes of the first rotary pair, the second rotary pair and the third rotary pair are parallel to each other. The branch chain formed by the moving pair, the first rotary pair, the second rotary pair and the third rotary pair has one degree of freedom, and under the joint action of the three PRRR branches, the dynamic platform has three-dimensional movement freedom. Meanwhile, on the basis of the moving pair, the first rotary pair, the second rotary pair and the third rotary pair, the horizontal spring and the vertical spring are combined to form a zero stiffness structure, so as to realize the three-dimensional zero stiffness characteristics.

[0029] When a three-dimensional vibration signal is applied to the dynamic platform, it is transmitted to the moving pairs (i.e. the moving pair, the first rotary pair, the second rotary pair and the third rotary pair) in each 3-PRRR parallel mechanism. Due to the arrangement form of the moving pairs of each branch, the Jacobian matrix of the parallel mechanism remains constant. Therefore, the stiffness matrix and the natural frequency of the vibration isolation platform do not change with the position of the platform, and the instantaneous natural frequency of the system does not change at any position of the vibration isolation platform. A zero stiffness mechanism based on a spring is designed in the sliding block of the moving pair, so that the vibration isolation platform can realize zero stiffness characteristics during movement in the X, Y and Z directions, thereby achieving good vibration isolation effect.

[0030] The support frame is provided with a sliding groove matched with the sliding block on each side, and the distance from the bottom surface of the sliding groove to the central axis of the support frame gradually decreases from top to bottom. Specifically, the sliding grooves on the two sides are arranged in inverted triangular shape. After such arrangement, when the sliding block moves from top to bottom, the compression amount of the spring on the two sides decreases, and the vertical spring compression amount increases, so that the zero stiffness characteristic can be realized by pre-adjusting the pre-compression amount of the spring.

[0031] The cross section of the sliding groove is isosceles trapezoidal. The isosceles trapezoidal sliding groove ensures the stability of the sliding block moving up and down in the sliding groove, thereby ensuring the working performance of the horizontal spring and the vertical spring.

[0032] The inner and outer sides of the support frame are provided with a constraint part, the sliding frame is provided with a groove matched with the constraint part, and the constraint part is embedded in the groove. This structure is simple, avoids shaking of the sliding frame when moving up and down, and ensures the stability of the sliding frame moving up and down.

[0033] The lower surface of the moving platform is provided with a rotating shaft mounting seat, the rotating shaft mounting seat is provided with a rotating shaft joint, the other end of the second connecting rod is provided with a first U-shaped joint matched with the rotating shaft joint, and the rotating shaft joint and the first U-shaped joint are hinged through a first hinge shaft. One end of the second connecting rod is provided with a second U-shaped joint matched with the other end of the first connecting rod, and the second U-shaped joint is hinged with the other end of the first connecting rod through a second hinge shaft. The arrangement of the U-shaped joint determines the stability of the connection between the two, so as to ensure the working performance of the rotating pair. In order to ensure the performance of the first rotating pair formed between the first connecting rod and the sliding frame, an inclined rod is arranged on the sliding frame, and the first connecting rod is hinged with the inclined rod.

[0034] Two horizontal springs are arranged in each sliding frame, and the two horizontal springs are arranged symmetrically with respect to the support frame. The symmetrical design structure further improves the stability of the sliding frame moving up and down.

[0035] The above specific embodiments are preferred embodiments of the present application, and cannot limit the present application. Any changes or other equivalent replacement manners without departing from the technical scheme of the present application are included in the protection scope of the present application.

Claims

1. A three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics, characterized in that, The system includes a static platform, a dynamic platform, and multiple PRRR branches. Each PRRR branch includes a support frame, a carriage, a first connecting rod, and a second connecting rod. The lower end of the support frame is fixed to the static platform via a base, and the base is equipped with a vertical spring. The carriage is sleeved on the upper end of the support frame and is slidably connected to it. The lower and upper ends of the vertical spring are fixed to the base and the carriage, respectively. One end of the first connecting rod is hinged to the carriage to form a first revolute joint, the other end of the first connecting rod is hinged to one end of the second connecting rod to form a second revolute joint, and the other end of the second connecting rod is hinged to the dynamic platform to form a third revolute joint. The central axes of the first, second, and third revolute joints are parallel to each other. A horizontal spring is provided inside the carriage. One end of the horizontal spring is slidably connected to the support frame via a slider, and the other end of the horizontal spring is fixed to the carriage.

2. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics according to claim 1, characterized in that: Both sides of the support frame are provided with sliding grooves that match the slider. The distance from the bottom surface of the sliding groove to the central axis of the support frame gradually decreases from top to bottom.

3. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics according to claim 2, characterized in that: The cross-section of the chute is an isosceles trapezoid.

4. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics according to claim 1, characterized in that: The support frame is provided with constraint parts on both the inner and outer sides, and the slide is provided with a groove that matches the constraint part, and the constraint part is embedded in the groove.

5. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics according to claim 1, characterized in that: The moving platform is provided with a rotating shaft mounting base, which is provided with a rotating shaft connector. The other end of the second connecting rod is provided with a first U-shaped connector that matches the rotating shaft connector. The rotating shaft connector and the first U-shaped connector are hinged together by a first hinge shaft.

6. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics according to claim 1, characterized in that: One end of the second link is provided with a second U-shaped connector that matches the other end of the first link. The second U-shaped connector is hinged to the other end of the first link through a second hinge shaft.

7. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics according to claim 1, characterized in that: There are three PRRR branches, which are evenly distributed relative to the center circumference of the static platform.

8. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics according to claim 1, characterized in that: Each carriage contains two horizontal springs, which are symmetrically arranged relative to the support frame.

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