Parallel vibration isolation platform with three-dimensional zero stiffness characteristic

Abstract

The invention discloses a three-degree-of-freedom parallel vibration isolation platform with a zero-stiffness characteristic. The three-degree-of-freedom parallel vibration isolation platform comprises a static platform, a movable platform and three PRRR branches, the PRRR branch comprises a supporting frame, a sliding frame, a first connecting rod and a second connecting rod, the lower end of the supporting frame is fixed to the static platform through a base, the base is provided with a vertical spring, the upper end of the supporting frame is sleeved with the sliding frame, the sliding frame is slidably connected with the supporting frame, and the lower end and the upper end of the vertical spring are fixed to the base and the sliding frame respectively; the carriage, the first connecting rod, the second connecting rod and the static platform form a first revolute pair, a second revolute pair and a third revolute pair which are parallel to one another; a horizontal spring is arranged in the sliding frame, one end of the horizontal spring is in sliding connection with the supporting frame through a sliding block, and the other end of the horizontal spring is fixed to the sliding frame. The three-degree-of-freedom vibration isolation mechanism has the flexible motion characteristic, meets the space three-degree-of-freedom vibration isolation requirement, and can achieve the zero-rigidity characteristic in the X direction, the Y direction and the Z direction.

Description

Technical Field

[0001] The invention relates to a vibration isolation platform, in particular to a parallel vibration isolation platform with three-dimensional zero-rigidity characteristics. Background Art

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

[0003] Zero-stiffness vibration isolators have high static and low dynamic characteristics in terms of system stiffness, that is, when the system is subjected to static load, the vibration isolator has a relatively high system stiffness and can provide sufficient support; when the system is subjected to dynamic load, the vibration isolator has a low system stiffness to achieve low-frequency and ultra-low-frequency vibration isolation. However, most of the nonlinear vibration isolators based on zero-stiffness theory can only achieve vibration reduction of specific controlled objects, and cannot meet the vibration isolation requirements of different objects. In addition, the low-stiffness displacement range of existing zero-stiffness vibration isolators is 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 increases, the vibration isolation frequency band becomes narrower, and the low-frequency vibration isolation performance decreases.

[0004] At the same time, there are many design schemes for single-degree-of-freedom zero-stiffness vibration isolators, but there are few studies on multi-degree-of-freedom, especially three-degree-of-freedom zero-stiffness vibration isolators. Therefore, when the instrument is actually used and subjected to disturbances in multiple directions, the vibration isolation effect is not good. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above prior art and 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-degree-of-freedom spatial translation vibration isolation, and can achieve zero stiffness characteristics in the three directions of X, Y, and Z.

[0006] The objective of the present invention is achieved through the following technical solutions: the 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; the PRRR branches comprise a support frame, a slide, 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 slide is sleeved on the upper end of the support frame, and the slide is slidably connected to the support frame, the lower end and the upper end of the vertical spring are respectively fixed to the base and the slide; one end of the first connecting rod is hinged to the slide to form a first rotating pair, the other end of the first connecting rod is hinged to one end of the second connecting rod to form a second rotating pair, the other end of the second connecting rod is hinged to the static platform to form a third rotating pair, and the central axes of the first rotating pair, the second rotating pair and the third rotating pair are parallel to each other; a horizontal spring is provided in the slide, one end of the horizontal spring is slidably connected to the support frame through a slider, and the other end of the horizontal spring is fixed to the slide.

[0007] Preferably, both sides of the support frame are provided with sliding grooves matching the sliding blocks, 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 slide groove is an isosceles trapezoid.

[0009] Preferably, the inner and outer sides of the support frame are both provided with restraining parts, the slide frame is provided with a groove matching the restraining part, and the restraining part is embedded in the groove.

[0010] Preferably, a rotating shaft mounting seat is provided under the moving platform, 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 matching the rotating shaft joint, and the rotating shaft joint and the first U-shaped joint are hinged through a first hinge shaft.

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

[0012] Preferably, the number of the PRRR branches is 3, and the 3 PRRR branches are evenly distributed relative to the central circumference of the static platform.

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

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

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

[0016] 2. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics of the present invention does not require a specific spring adjustment mechanism. The compression of the horizontal spring is adjusted by the distance between the support frame and the inside of the slider, so that the overall movement is more sensitive and more stable than the vibration isolation platforms on the market.

[0017] 3. The three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics of the present invention can adjust its performance according to the change of load, ensuring that it can provide a stable vibration isolation effect under different load conditions, and can achieve vibration isolation control in different frequency ranges with precise positioning.

[0018] 4. The traditional vibration isolation platform has only a single degree of freedom vibration isolation effect and a small scope of engineering application, while the present invention has three translational degrees of freedom, a large operating space, and a wide range of engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0022] Figure 4 It is a schematic diagram of the connection between the horizontal spring and the slider of the present invention.

[0023] Figure 5 It is a structural schematic diagram of the moving platform of the present invention.

[0024] Figure 6 It is a structural schematic diagram of the support frame and the static platform of the present invention.

[0025] Among them, 1 is a static platform, 2 is a dynamic platform, 3 is a 3-PRRR parallel mechanism, 4 is a support frame, 5 is a slide 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 rotating pair, 11 is a second rotating pair, 12 is a third rotating pair, 13 is a horizontal spring, 14 is a slider, 15 is a slide groove, 16 is a constraint part, 17 is a groove, 18 is a shaft mounting seat, 19 is a shaft joint, 20 is a first U-shaped joint, 21 is a second U-shaped joint, and 22 is a diagonal rod. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] like Figures 1 to 6As shown, a three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics includes a static platform, a dynamic platform and multiple PRRR branches; the PRRR branches include a support frame, a slide, 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 slide is sleeved on the upper end of the support frame, and the slide is slidably connected to the support frame, the lower end and upper end of the vertical spring are respectively fixed to the base and the slide; one end of the first connecting rod is hinged to the slide to form a first rotating pair, the other end of the first connecting rod is hinged to one end of the second connecting rod to form a second rotating pair, the other end of the second connecting rod is hinged to the static platform to form a third rotating pair, and the central axes of the first rotating pair, the second rotating pair and the third rotating pair are parallel to each other; a horizontal spring is provided in the slide, one end of the horizontal spring is slidably connected to the support frame through a slider, and the other end of the horizontal spring is fixed to the slide.

[0028] Specifically, the static platform and the dynamic platform are made of triangular flat plates, and the two are arranged in parallel. The number of PRRR branches in this embodiment is 3, and the 3 PRRR branches are evenly distributed relative to the central circumference of the static platform. That is, with the center line of the static platform as the center, the arc angle between two adjacent PRRR branches is arranged at 120 degrees. In this way, the static platform, the dynamic platform and the three PRRR branches constitute a 3-PRRR parallel mechanism. In each PRRR branch, the slide slides up and down on the support frame to form a moving pair, one end of the first connecting rod is hinged to the slide to form a first rotating pair, the other end of the first connecting rod is hinged to one end of the second connecting rod to form a second rotating pair, and the other end of the second connecting rod is hinged to the static platform to form a third rotating pair, and the central axes of the first rotating pair, the second rotating pair and the third rotating pair are parallel to each other; the branch chain composed of the moving pair, the first rotating pair, the second rotating pair and the third rotating pair has one degree of freedom. Under the joint action of the three PRRR branches, the moving platform has three-dimensional movement freedom; at the same time, on the basis of the moving pair, the first rotating pair, the second rotating pair and the third rotating pair, horizontal springs and vertical springs are combined to form a zero stiffness structure to achieve zero stiffness characteristics in three-dimensional directions.

[0029] When the three-dimensional vibration signal in space is applied to the moving platform, it is transmitted to the kinematic pairs in each 3-PRRR parallel mechanism (i.e., the moving pair, the first rotating pair, the second rotating pair, and the third rotating pair). Due to the composition of the kinematic pairs of each branch, the layout determines that the Jacobian matrix of the parallel mechanism remains constant. Therefore, during the operation of the vibration isolation platform, its stiffness matrix and natural frequency will not change with the position of the platform, and the instantaneous natural frequency of the system at any position of the vibration isolation platform will not change. A spring-based zero stiffness mechanism is designed inside the moving pair slider. Therefore, the vibration isolation platform can achieve zero stiffness characteristics during the movement along the three directions of X, Y, and Z, thereby achieving a good vibration isolation effect.

[0030] Both sides of the support frame are provided with a slide groove matching the slider, and the distance from the bottom surface of the slide groove to the central axis of the support frame gradually decreases from top to bottom. Specifically, the slide grooves on both sides are arranged in an inverted triangle. After such arrangement, when the slider moves from top to bottom, the compression amount of the springs on both sides decreases, and the compression amount of the vertical spring increases. By pre-adjusting the pre-compression amount of the spring, the zero stiffness characteristic can be achieved.

[0031] The cross section of the slide groove is an isosceles trapezoid. The isosceles trapezoidal slide groove ensures the stability of the slider moving up and down in the slide 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 both provided with a restraining part, the slide frame is provided with a groove matching the restraining part, and the restraining part is embedded in the groove. This structure is simple, and shaking of the slide frame when it moves up and down is avoided, so as to ensure the stability of the slide frame when it moves up and down.

[0033] A rotating shaft mounting seat is provided below the moving platform, and 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 matching the rotating shaft joint, and the rotating shaft joint and the first U-shaped joint are hinged through a first hinge shaft. A second U-shaped joint is provided at one end of the second connecting rod to match the other end of the first connecting rod, and the second U-shaped joint is hinged to the other end of the first connecting rod through a second hinge shaft. The setting of the U-shaped joint determines the stability of the connection between the two 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 slide, a tilting rod is provided on the slide, and the first connecting rod is hinged to the tilting rod.

[0034] Each slide is provided with two horizontal springs, which are symmetrically arranged relative to the support frame. The symmetrical design structure further improves the stability of the slide when moving up and down.

[0035] The above specific implementation modes are preferred embodiments of the present invention and cannot be used to limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. A three-degree-of-freedom parallel vibration isolation platform with zero stiffness characteristics, characterized in that: It includes a static platform, a dynamic platform and multiple PRRR branches, the PRRR branches include a support frame, a slide, 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 slide is sleeved on the upper end of the support frame, and the slide is slidably connected to the support frame, the lower end and upper end of the vertical spring are respectively fixed to the base and the slide; one end of the first connecting rod is hinged to the slide to form a first rotating pair, the other end of the first connecting rod is hinged to one end of the second connecting rod to form a second rotating pair, the other end of the second connecting rod is hinged to the static platform to form a third rotating pair, and the central axes of the first rotating pair, the second rotating pair and the third rotating pair are parallel to each other; a horizontal spring is provided in the slide, one end of the horizontal spring is slidably connected to the support frame through a slider, and the other end of the horizontal spring is fixed to the slide.

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 matching the sliding blocks, 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.

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 inner and outer sides of the support frame are both provided with restraining parts, the sliding frame is provided with a groove matching with the restraining part, and the restraining 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: A rotating shaft mounting seat is provided under the moving platform, and 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 matching the rotating shaft joint. The rotating shaft joint and the first U-shaped joint are hinged through 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 connecting rod is provided with a second U-shaped joint matching the other end of the first connecting rod, and the second U-shaped joint is hinged to the other end of the first connecting rod 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: The number of PRRR branches is 3, and the 3 PRRR branches are evenly distributed relative to the central 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: Two horizontal springs are arranged in each slide frame, and the two horizontal springs are symmetrically arranged relative to the support frame.

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