CN111609081A - A Novel Vibration Damping Device Based on Stewart Configuration - Google Patents

Abstract

The invention discloses a novel vibration reduction device based on a Stewart configuration, which relates to the technical field of vibration reduction, and comprises an upper platform, a lower platform and a plurality of single-leg vibration reduction units. The two orthogonal ways are connected with the upper and lower platforms to form a cubic structure vibration reduction platform. The cubic Stewart space configuration is used to solve the problem of decoupling, which can not only ensure the stable connection between sensors such as hydrophones and the basic working surface, but also can effectively reduce the displacement transmissibility of the hydrophone and make the displacement transmissibility more efficient. Small, low-frequency vibration reduction has lower natural frequency, better low-frequency vibration isolation performance, and can greatly reduce the ground vibration of the sensor, enabling it to obtain high measurement accuracy in harsh marine conditions. The invention is suitable for vibration reduction of instruments operating in the marine environment, can greatly increase the acoustic stealth performance of the surface unmanned boat, and improve the working environment of the sensor on the unmanned boat.

Description

A Novel Vibration Damping Device Based on Stewart Configuration

technical field

The invention relates to the technical field of vibration reduction, in particular to a novel vibration reduction device based on Stewart configuration.

Background technique

In recent years, the demand for intelligent surface transportation has gradually increased. For a smart carrier full of sensors such as lidars and hydrophones, vibration is an unavoidable effect, and the harsh marine environment, such as inrush currents in the ocean, will seriously affect the performance of the sensor.

Traditional sensors such as hydrophones and lidars are often connected and installed by rigid connection with the working base. The traditional rigid connection has great advantages in connection strength and better fixing performance. However, this kind of rigid connection is faced with problems such as strong load shock and platform vibration. These shocks and vibrations seem to be insignificant for general-purpose machines, but they cannot be ignored for sensors that require high precision, and even directly affect the detection performance of the sensor.

In order to eliminate the above effects brought about by the rigid connection, the patent No. CN109854672A discloses a double diaphragm spring type low frequency vibration isolator. Although it uses the low stiffness characteristics of the diaphragm spring and the series characteristics of elastic elements to achieve good low-frequency vibration isolation performance, due to the single-leg structure design, the displacement transmissibility and low-frequency vibration isolation performance cannot meet the requirements of intelligent water transportation. high anti-vibration requirements, especially in terms of reducing the foundation vibration of the sensor. Therefore, in order to obtain higher measurement accuracy in harsh marine conditions, how to propose a method that can not only ensure a stable connection between sensors such as hydrophones and the basic working surface, but also effectively reduce the displacement transfer rate of the sensor. Vibration damping device is one of the problems to be solved urgently at present.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a novel vibration damping device based on Stewart configuration with reasonable structural design, which can not only ensure the stable connection between sensors such as hydrophones and the basic working surface, but also can greatly reduce the foundation of the sensor. Vibration, to solve the vibration problem in the low frequency band of sensors such as hydrophones, so that it can obtain high measurement accuracy in harsh marine conditions.

For achieving the above object, the present invention provides the following scheme:

The present invention provides a novel vibration damping device based on Stewart configuration, comprising an upper platform, a lower platform, and a plurality of single-leg vibration damping units connected between the upper platform and the lower platform, and each adjacent two The single-leg vibration-damping units are connected with the upper and lower platforms in a space-to-space orthogonal manner to form a cube-structure vibration-damping platform.

Optionally, the upper platform and/or the lower platform are respectively installed with a plurality of corner seats for connecting the single-leg vibration reduction unit, and the single-leg vibration reduction unit is connected with the free end of the corner seat. .

Optionally, the corner seat is threadedly connected to the upper platform and/or the lower platform.

Optionally, a square groove is formed on the upper platform and/or the lower platform to limit the rotation of the corner seat.

Optionally, a limit rod is installed between the upper platform and the lower platform.

Optionally, three limit rods are installed vertically, and the cross sections of the three limit rods are arranged at 60 degrees to each other.

Optionally, there are six single-leg vibration reduction units.

Optionally, the single-leg vibration-damping unit is a double-diaphragm spring-type vibration isolator, including an upper support unit and a lower support unit arranged oppositely, and the upper support unit and the lower support unit are respectively connected with a diaphragm spring. , the two diaphragm springs are connected by an intermediate shaft.

Optionally, the upper support unit and/or the lower support unit are respectively connected with three diaphragm spring brackets that are spaced 120 degrees from each other, and the diaphragm springs are bolted to the diaphragm spring brackets.

Optionally, the diaphragm spring is a hollow design, and the shape of the hollow area is the name of the mechanism.

The present invention has achieved the following technical effects with respect to the prior art:

The novel vibration damping device based on the Stewart configuration provided by the present invention adopts the cubic Stewart spatial configuration to solve the problem of decoupling difficulty, which can not only ensure the stable connection between sensors such as hydrophones and the basic working surface, but also can effectively It can greatly reduce the displacement transmissibility of the hydrophone, so that the displacement transmissibility is smaller, the natural frequency of low-frequency vibration damping is lower, and the low-frequency vibration isolation performance is better, and the foundation vibration of the sensor can be greatly reduced, so that it can be used in harsh environments. High measurement accuracy is also obtained in marine conditions. The invention is suitable for vibration reduction of instruments operating in the marine environment, can greatly increase the acoustic stealth performance of the surface unmanned boat, and improve the working environment of the sensor on the unmanned boat. The invention has important significance for studying the vibration damping technology under complex ocean conditions.

In addition, in the present invention, a limit rod is installed between the upper and lower platforms, which can avoid the damage of the diaphragm spring on the single-leg vibration damping unit caused by a large impact load. The upper and lower support units of the single-leg vibration-damping unit of the present invention are designed with flexible hinges, which can realize the adjustment of the micro-deformation in the axial direction of the single-leg, and improve the accuracy of the cube structure.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the structural representation of the novel damping device based on Stewart configuration of the present invention;

Fig. 2 is the structural principle diagram of the novel damping device based on Stewart configuration of the present invention;

3 is a schematic structural diagram of a single-leg vibration reduction unit of the present invention;

4 is a schematic structural diagram of an upper support unit in the single-leg vibration reduction unit of the present invention;

5 is a schematic structural diagram of a diaphragm spring in the single-leg vibration damping unit of the present invention;

6 is a schematic structural diagram of a lower support unit in the single-leg vibration reduction unit of the present invention;

Figure 7-1 is the working principle diagram of the traditional vibration reduction mode;

Figure 7-2 is the working principle diagram of the existing single-degree-of-freedom vibration reduction mode;

Fig. 7-3 is the working principle diagram of the six-degree-of-freedom vibration reduction mode of the first embodiment;

Fig. 8 is a graph showing the comparison of transmissibility of traditional, single-degree-of-freedom and six-degree-of-freedom vibration damping modes;

Wherein, the reference signs are: 1-upper platform; 2-corner seat; 3-single-leg damping unit; 31-upper support unit 32-upper casing; 33-diaphragm spring bracket; 34-diaphragm spring; 35- Intermediate shaft; 36-lower housing; 37-lower support unit; 4-lower platform; 5-limiting rod.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Example 1:

As shown in FIGS. 1-3 , this embodiment provides a new type of vibration damping device based on the Stewart configuration, including an upper platform 1 , a lower platform 4 , and six single-leg dampers connected between the upper platform 1 and the lower platform 4 . Vibration units 3 are formed, and every two adjacent single-leg vibration reduction units 3 are connected to the upper and lower platforms in a space-to-square manner to form a cubic structure vibration reduction platform.

In this specific embodiment, the upper platform 1 and the corner seat 2 are threadedly connected by bolts, and the lower part of the corner seat 2 is a fixed table with a fixed angle. Orthogonality of the single-leg damping unit 3 . The single-leg damping unit 3 and the corner seat 2 are also threadedly connected with bolts. The lower platform 4 and the corner seat 2 are also threadedly connected by bolts. The purpose of adopting this angle seat connection is to reduce the processing difficulty of punching holes on the upper platform, and to convert the operation of five-axis CNC machine tools into three-axis CNC machine tools.

In this embodiment, as shown in FIG. 1 , in order to protect the single-leg unit on the platform, the device also adds three limit rods 5 installed vertically between the upper and lower platforms with a cross-section of 60 degrees. Avoid the damage of the diaphragm spring on the single-leg damping unit 3 due to the large impact load.

In this embodiment, the connection between the upper and lower platforms and the corner seat 2 is not directly connected. By machining square grooves on the mounting surfaces of the upper and lower platforms, the rotation of the corner seat 2 is restricted, thereby ensuring that the single-leg reduction is reduced. The installation of the vibration unit is a cubic structure.

In this embodiment, the single-leg vibration reduction unit 3 occupies an important position. As shown in FIGS. 3 to 6 , the single-leg vibration damping unit 3 is mainly composed of an upper support unit 31 , an upper casing 32 , a diaphragm spring bracket 33 , a diaphragm spring 34 , an intermediate shaft 35 , a lower casing 36 , and a lower supporting unit 37 , etc. composition. The top of the upper support unit 31 is used for connecting with the object to be vibration-isolated, and the bottom is connected with three diaphragm spring brackets 33 using bolts and threads, and the three diaphragm spring brackets 33 are 120 degrees from each other in space. The three diaphragm spring brackets 33 and the diaphragm springs 34 are connected by bolts and nuts. An intermediate shaft 35 and a double-ended stud are used for screw connection between the two diaphragm springs 34 . The lower diaphragm spring 34 is also connected with three diaphragm spring brackets 33 which are 120 degrees from each other. The diaphragm spring brackets 33 are connected with the top of the lower support unit 37 through bolts, and the bottom of the lower support unit 37 is used for vibration. source connected. The upper and lower support units in this embodiment are designed with flexible hinges, which can finely adjust the orthogonal angle. It greatly reduces the difficulty of processing and installation, and is more applicable to the working conditions of the device. At the same time, the upper and lower support units and the diaphragm spring are connected by three brackets at 120 degrees to each other, which can not only ensure the stability of the connection, but also reduce the processing difficulty and production cost for mass production.

In this embodiment, as shown in FIG. 3 , the lower support unit 37 is connected to the lower housing 36 by bolts, the lower housing 36 and the upper housing 32 are connected by several small bolts, and the lower housing 36 and the upper housing 32 are connected by butting together. Completed encapsulation for protection of double diaphragm spring mounted low frequency vibration isolators.

In this embodiment, as shown in FIG. 5 , the hollow shape of the diaphragm spring 34 may preferably be a combination of “SHANGHAIUNIVERSITY” and “SHU”. Such hollow design is simple and elegant, and has an anti-plagiarism function, and its hollow size can directly affect The stiffness of the diaphragm spring is indirectly based on the stiffness Jacobian transformation matrix, thereby affecting the stiffness performance of the whole machine and further affecting the vibration reduction performance of the whole machine. The vibration suppression frequency range of the hollow diaphragm spring is larger than that of the non-perforated circular diaphragm spring. In this embodiment, two diaphragm springs are used, which increases the elastic modulus of the leg unit and reduces the stiffness of the system to a greater degree. For different operating occasions, diaphragm springs of different materials can be used for work. For example, 65Mn and damping steel can be used to achieve different stiffnesses. Coating anti-corrosion materials on the surface of diaphragm springs can improve corrosion resistance.

In this embodiment, the single-leg vibration reduction unit 3 is connected in the manner shown in FIG. 2 . Nodes 2, 4, and 6 represent the plane where the load platform is located, and nodes 1, 3, and 5 represent the plane where the ground platform is located. The six edges 1_2, 1_6, 3_4, 3_2, 5_4, and 5_6 of the cube in Fig. 2 are the axial positions of the six degrees of freedom of the Stewart configuration, respectively. The single-leg vibration-damping units 3 with six different degrees of freedom are connected in the above manner, which is the cubic vibration-damping structure in this embodiment. Due to errors in the process of processing and installation, this error will cause the actual six-degree-of-freedom single-leg vibration reduction unit 3 to not be spatially orthogonal. Although the angle is approximately 90 degrees, it will have a great impact on the measurement accuracy of the instrument for precision instruments used in heading operations. Therefore, a flexible hinge is added on the upper and lower support units. Due to the existence of the flexible hinge, the angle of the single-leg vibration reduction unit 3 can be adjusted within ±1 degree, which greatly reduces the difficulty of assembly and processing.

The working principle of this embodiment is described in detail below:

Different from the traditional vibration damper, the vibration damping structure of this embodiment is mainly used for instruments working in the marine environment, such as hydrophones. Fixing the hydrophone on the load platform of the device can greatly reduce the vibration in the working environment of the hydrophone. When a vibration source is generated on the load plane, the load platform will move irregularly due to the disturbance. These impact forces are transmitted to the single-leg vibration damping unit 3 through the corner seat of the lower platform 4 . The upper support unit 31 of the single-leg vibration damping unit 3 transmits the vibration to the diaphragm spring 34 . Since the diaphragm spring has a good elastic modulus, the vibration of the upper platform 1 will make the diaphragm spring on the upper part of the single-leg vibration damping unit 3 . 34 does the following movement, because the speed of the impact is transmitted very fast, the lower part has not had time to move, so as to achieve the effect of vibration reduction. When the impact load is very large, the limit rod 5 between the upper and lower platforms plays a role, and has a certain overload protection effect on the single-leg vibration damping unit 3 .

As shown in Figure 7-1, it is a schematic diagram of the stiffness damping of the traditional connection method, which consists of a simple spring, mass and damping. Its displacement transmissibility curve function is as follows:

where x ₁ and x ₂ are the vibration displacement deflection of the load platform and the displacement deflection of the foundation platform respectively, c is the equivalent damping of the system, k is the equivalent stiffness of the system, m is the mass of the load platform, and s is the tension type operator. The above parameters can be obtained through the prior art, and are not repeated here.

As shown in Figure 7-2, it is the structural schematic diagram of the existing single-degree-of-freedom shock absorber, and its transmissibility curve function is as follows:

where x ₁ and x ₂ are the vibration displacement deflection of the load platform and the displacement deflection of the foundation platform respectively, c is the equivalent damping of the system, k' is the equivalent stiffness of the system, the stiffness of the support element on k ₁ , k ₂ is The stiffness of the lower support unit, m is the mass of the load platform, and s is the pull operator. The above parameters can be obtained through the prior art, and are not repeated here.

As shown in FIG. 7-3 , it is a schematic structural diagram of the Stewart platform of the cube structure of this embodiment. The stiffness and damping in its six degrees of freedom are vectors along the six single-leg directions, respectively. Decouple it along the x, y, z directions:

where m _x , m _y , and m _z represent the masses in the three directions of x, y, and z, respectively; x ₀ , y ₀ , and z ₀ represent the displacements in the three directions, respectively, and the first-order and second-order derivatives represent the velocity and Acceleration; c _x , c _y , c _z represent the damping in the three directions of x, y, and z; f _x , f _y , f _z represent the resultant force in the three directions of x, y, and z; M _α , J _α , α respectively Represents the resultant moment, moment of inertia, and angular displacement in the x direction; the y and z directions are analogous to the x direction.

As shown in Figure 8, it is the displacement transmissibility curve diagram of the three cases of Figure 7-1, 7-2, and 7-3. It can be seen from the figure that the traditional connection method is used, and the resonance peak and resonance frequency are large. This method is very poor in anti-low frequency interference. When a single-degree-of-freedom shock absorber is used, the resonance peak and natural frequency can be effectively reduced, but the effect of low-frequency vibration suppression is not ideal. It can be seen from the curve that the device of the present invention can effectively reduce the resonance peak value and the natural frequency, and the low-frequency vibration reduction performance is relatively superior.

When designing the Stewart device in this embodiment, a single single-leg vibration reduction unit 3 is firstly modeled and simulated. According to the simulation results, the single-leg vibration reduction unit 3 is designed. The main working element on the single-leg vibration damping unit 3 is the diaphragm spring 34. By changing the thickness and material of the diaphragm spring 34, the elastic modulus of the diaphragm spring can be changed, and finally the stiffness and damping of the single-leg vibration damping unit 3 can be changed. . The stiffness and damping of the single-leg vibration reduction unit 3 are coupled to reduce the stiffness of the system, so that the natural frequency changes according to the requirements, so as to achieve the purpose of the Stewart platform for vibration reduction and noise reduction in the low frequency band of the hydrophone.

This embodiment adopts two upper and lower working platforms designed on a cubic structure, and the two adjacent single-leg vibration reduction units 3 are connected to the upper and lower platforms in a space-wise orthogonal manner. Compared with the traditional non-cube structure, the cubic structure using the device has many advantages. For the traditional non-cubic structure, when the Stewart platform is subject to external disturbances, the non-cubic structure platform is not orthogonal because the leg elements are adjacent to each other, so from the platform vibration analysis to the single-leg element analysis, there will be It becomes very difficult because the coupling problem of non-cubic structures is very serious, the requirements for spatial decoupling are very high, and it is often difficult to decouple or decoupling errors occur. The device adopts the structure of a space cube. When subjected to external force, the six single-leg vibration-damping units 3 will expand and contract at the same time, thereby isolating the vibration of the six-degree-of-freedom single-leg vibration-damping units 3 . Due to the unique spatial structure, the device is automatically decoupled, which fundamentally avoids complex decoupling problems.

It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. . Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes that come within the meaning and range of equivalents of , are intended to be embraced within the invention, and any reference signs in the claims shall not be construed as limiting the involved claim.

In the present invention, specific examples are used to illustrate the principles and implementations of the present invention, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention; There will be changes in the specific implementation manner and application scope of the idea of the invention. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. A novel vibration damping device based on Stewart configuration, characterized in that: it comprises an upper platform, a lower platform, and a plurality of single-leg vibration damping units connected between the upper platform and the lower platform, and each phase The two adjacent single-leg vibration-damping units are connected with the upper and lower platforms in a space-to-square manner to form a cube-structure vibration-damping platform. 2 . The new type of vibration damping device based on Stewart configuration according to claim 1 , wherein: the upper platform and/or the lower platform are respectively provided with a plurality of A corner seat, the single-leg vibration damping unit is connected with the free end of the corner seat. 3 . The novel vibration damping device based on the Stewart configuration according to claim 2 , wherein the corner seat is screwed to the upper platform and/or the lower platform. 4 . 4 . The novel vibration damping device based on Stewart configuration according to claim 2 , wherein a square groove is formed on the upper platform and/or the lower platform for the rotation of the corner seat. 5 . limit. 5 . The novel vibration damping device based on Stewart configuration according to claim 1 , wherein a limit rod is installed between the upper platform and the lower platform. 6 . 6 . The new type of vibration damping device based on Stewart configuration according to claim 5 , wherein three limit rods are installed vertically, and the cross sections of the three limit rods are arranged at 60 degrees to each other. 7 . 7 . The novel vibration reduction device based on the Stewart configuration according to claim 1 , wherein there are six of the single-leg vibration reduction units. 8 . 8 . The new type of vibration damping device based on Stewart configuration according to claim 1 , wherein the single-leg vibration damping unit is a double-diaphragm spring type vibration isolator, comprising an upper support unit and a lower support arranged oppositely. 9 . The upper support unit and the lower support unit are respectively connected with a diaphragm spring, and the two diaphragm springs are connected by an intermediate shaft. 9 . The novel vibration damping device based on Stewart configuration according to claim 8 , wherein the upper support unit and/or the lower support unit are respectively connected with three diaphragms that are 120 degrees from each other in space. 10 . A spring bracket, the diaphragm spring is bolted to the diaphragm spring bracket. 10 . The novel vibration damping device based on the Stewart configuration according to claim 8 , wherein the diaphragm spring is a hollow design, and the shape of the hollow area is the name of the mechanism. 11 .

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