CN113513559B - A Stewart vibration isolation platform based on MFC forward and reverse piezoelectric effect - Google Patents

Abstract

The invention discloses a Stewart vibration isolation platform based on the forward and reverse piezoelectric effect of MFC, which includes an upper platform of a load and a lower platform of a foundation, three corner positions of the upper platform of a load are respectively fixedly connected with an upper adapter, and three corners of the lower platform of a foundation are respectively fixedly connected. One lower adapter is connected to each of the corner positions, and six single-leg vibration isolation units are connected between the three upper adapters and the three lower adapters; each support beam of the load platform is equipped with three pairs of MFC piezoelectric fibers Each pair of MFC piezoelectric fiber patches includes an MFC sensor and an MFC actuator, and the MFC sensor and MFC actuator in each pair of MFC piezoelectric fiber patches can exchange roles, and the MFC sensor and MFC The actuators are respectively electrically connected to the controller through wires. The combination of multiple MFC sensors, MFC actuators and controllers in the present invention can realize active control vibration reduction, and adopt active and passive composite vibration reduction technology, which can reduce the resonance peak while ensuring high-frequency attenuation rate and achieving better isolation vibration effect.

Description

A Stewart vibration isolation platform based on MFC forward and reverse piezoelectric effect

technical field

The invention relates to the technical field of precision vibration isolation, in particular to a Stewart vibration isolation platform based on MFC forward and reverse piezoelectric effects.

Background technique

In recent years, with the increase in the use of precision equipment, the performance requirements have become higher, and the vibration isolation requirements for precision equipment have also continued to increase. Among the many vibration isolators, the vibration isolation platform based on the Stewart platform has become one of the most concerned vibration isolation methods because of its characteristics of easy decoupling and large load capacity. Common vibration isolation technologies are divided into passive vibration isolation and active vibration isolation, among which active vibration isolation has been widely studied and applied because of its good performance.

The vibration isolation performance of active vibration isolation is mainly determined by actuators. Common actuators include piezoelectric, electromagnetic, hydraulic, etc. Among them, piezoelectric actuators have the advantages of low power consumption, high response, and high precision. protrude. Common piezoelectric actuators include stacked, sheet ceramic, MFC (piezoelectric fiber composite), etc. MFC has the characteristics of light weight, small size, fast response, high precision, large operating power, and low stiffness. It can be used as a sensor and an actuator at the same time, and it is flexible to use.

Chinese patent document CN108593246A provides an active vibration suppression device based on a piezoelectric ceramic wind tunnel model. The device uses an appropriate number of piezoelectric ceramics as actuators, and is installed in multiple stepped grooves on the tail support rod. Using the characteristics of fast dynamic response and large actuating power of piezoelectric ceramics, it can control the pitch and yaw of the model. Vibration is effectively suppressed. But there is no research on the detection of vibration interference signal and active vibration isolation control.

Chinese patent document CN111458013A provides a piezoelectric fiber composite (MFC) sensing device for platform vibration isolation. The device is made of piezoelectric ceramic fiber composite material, which uses its high precision and fast response to capture vibration energy in all directions and convert it into electrical signals, thereby realizing the function of a sensor. But its function is single, and the effect of the actuator is not considered.

Contents of the invention

The purpose of the present invention is to provide a Stewart vibration isolation platform based on MFC positive and negative piezoelectric effects to solve the problems in the prior art. The active and passive composite vibration reduction technology can reduce the resonance peak while ensuring high frequency The attenuation rate achieves a good vibration isolation effect, and the response is sensitive, safe and reliable.

To achieve the above object, the present invention provides the following scheme:

The present invention provides a Stewart vibration isolation platform based on MFC forward and reverse piezoelectric effect, which includes a load upper platform and a foundation lower platform respectively in a triangular structure, and the vertical projection of the three angles after the load upper platform rotates 120 degrees horizontally and The vertical projections of the three corners of the lower platform of the foundation are coincident, the three corner positions of the upper platform of the load are respectively fixedly connected with an upper transfer joint, and the three corner positions of the lower platform of the foundation are respectively connected with a The lower transfer joints, six single-leg vibration isolation units are connected between the three upper transfer joints and the three lower transfer joints, the adjacent single-leg vibration isolation units are perpendicular to each other, and the opposite single-leg vibration isolation units are connected to each other Parallel, the overall cubic configuration is convenient for decoupling; each support beam of the load platform is equipped with three pairs of MFC piezoelectric fiber patches, and each pair of MFC piezoelectric fiber patches includes an MFC sensor and an MFC Actuators, using the positive and negative effects of piezoelectricity, each MFC in each pair of MFC piezoelectric fiber patches can switch the roles of sensors and actuators according to actual needs, and only need to be based on the positive and negative effects of piezoelectricity. Inverse effect, just switch in the control loop. That is, each pair of MFC piezoelectric fiber patches in the present invention can be used as both an MFC sensor and an MFC actuator, and can realize the same material/device, the exchange of the roles of the MFC sensor and the actuator, and the MFC The sensors and the MFC actuators are respectively electrically connected to the controller through wires, and multiple MFC sensors and MFC actuators are combined with the controller to realize active control of vibration reduction.

Optionally, the six single-leg vibration isolation units have the same structure; each of the single-leg vibration isolation units includes an upper end cover, a middle cage and a lower end cover fixedly connected in sequence; a compression spring is arranged inside the upper end cover The top end of the compression spring negative stiffness structure penetrates the upper end cover and is connected with an upper flexible hinge, and the bottom of the lower end cover is fixedly connected with a lower flexible hinge.

Optionally, two connecting flanges are fixedly arranged on the inner wall of the upper end cover; the compression spring type negative stiffness structure includes a three-way adapter, and the two ends of the three-way adapter are located at the bottom respectively through the compression spring and the The connecting flange on the inner wall of the upper end cover is fixedly connected, the upper end of the three-way adapter is fixedly connected with a support rod through a compression spring, and the support rod penetrates the top of the upper end cover and is fixedly connected with the upper flexible hinge .

Optionally, a connection block is provided on one side of the top of the upper transfer joint, and two parallel first connection holes are opened on the connection block, and two symmetrical openings are provided on the side of the upper transfer joint near the connection block The two inclined surfaces are provided with two vertically arranged second connection holes, and the structure of the upper transfer joint is the same as that of the lower transfer joint; the first connection hole of the upper transfer joint is connected to the The upper platform of the load is fixedly connected, and the first connection hole of the lower adapter is fixedly connected with the lower platform of the foundation through screws.

Optionally, the three upper transfer joints are respectively the first upper transfer joint, the second upper transfer joint and the third upper transfer joint, and the three lower transfer joints are respectively the first lower transfer joint and the second lower transfer joint. connector and the third lower adapter; the six single-leg vibration isolation units are respectively the first single-leg vibration isolation unit, the second single-leg vibration isolation unit, the third single-leg vibration isolation unit, and the fourth single-leg vibration isolation unit , the fifth single-leg vibration-isolation unit and the sixth single-leg vibration-isolation unit; the two second connection holes of the first upper adapter are respectively connected to the upper ends of the first single-leg vibration-isolation unit and the sixth single-leg vibration-isolation unit The flexible hinge is fixedly connected, and the two second connection holes of the second upper transfer joint are fixedly connected with the upper end flexible hinges of the second single-leg vibration isolation unit and the third single-leg vibration isolation unit respectively, and the third upper transfer joint The two second connection holes of the first lower adapter are respectively fixedly connected with the upper end flexible hinges of the fourth single-leg vibration isolation unit and the fifth single-leg vibration isolation unit; The leg vibration isolation unit is fixedly connected with the flexible hinge at the lower end of the second single leg vibration isolation unit, and the two second connection holes of the second lower transfer joint are connected with the third single leg vibration isolation unit and the fourth single leg vibration isolation unit respectively. The lower ends of the flexible hinges are fixedly connected, and the two second connection holes of the third lower adapter are respectively fixedly connected with the lower end flexible hinges of the fifth single-leg vibration isolation unit and the sixth single-leg vibration isolation unit.

Optionally, the three MFC sensors provided on each support beam of the loading platform are respectively the first MFC sensor, the second MFC sensor and the third MFC sensor, and the three MFC actuators are the first MFC actuators respectively. actuator, the second MFC actuator and the third MFC actuator; the first MFC sensor and the first MFC actuator are symmetrically arranged on the upper and lower surfaces of the load platform support beam, and the first The second MFC sensor and the second MFC actuator are symmetrically embedded in the cross section of the load upper platform, and the third MFC sensor and the third MFC actuator are symmetrically arranged on the upper and lower sides of the load upper platform support beam. on a surface; the second MFC sensor and the second MFC actuator are located between the first MFC sensor and the third MFC sensor. One pair is embedded in the transverse section of the platform support on the load, which can cause the platform support on the load to produce lateral micro-displacement; the other two pairs are embedded on the surface of the platform support on the load, which can cause the platform support on the load to produce vertical micro-displacement . The sensor perceives the external vibration signal, transmits the vibration signal to the controller through the wire, and the controller transmits the control signal to the actuator through the wire, and controls the displacement of the actuator in real time to offset the external vibration.

Optionally, symmetrical connecting threaded holes are respectively opened on the end surfaces of the upper end cover, the middle cage and the lower end cover, and the connecting threaded holes are used for passing long bolts, and the upper end cover, the middle cage and the The lower end covers are fixedly connected by long bolts.

Optionally, the load upper platform has an isosceles triangle structure, and horizontal connection end surfaces are provided at the outer positions of the three corners of the load upper platform, and the upper transfer joint is fixedly arranged at the horizontal connection end surface. Three reinforcing rods are arranged in the upper platform of the load, one end of the three reinforcing rods is respectively connected to a corner of the upper platform of the load, and is located on the bisector of the corner, and the other ends of the three reinforcing rods are on the The center of the circumscribed circle of the upper platform of the load is fixedly connected; the lower platform of the foundation is an isosceles triangle structure, and a horizontal connection end surface is provided at the outer positions of the three corners of the lower platform of the foundation, and the lower transfer joint is fixedly arranged At the end face of the horizontal connection, three reinforcement rods are arranged in the lower platform of the foundation, and one end of the three reinforcement rods is respectively connected to a corner of the lower platform of the foundation, and is located on the bisector of the corner. The other ends of the reinforcing rods are fixedly connected at the center of the circumscribed circle of the platform under the foundation.

Optionally, the width of the reinforcing bar of the platform on the load is smaller than the width of the support beam of the platform on the load; so that the MFC piezoelectric fiber press sheet plays a major role. The width of the reinforcing bar of the platform under the foundation is greater than the width of the supporting beams of the platform under the foundation, so as to improve the bearing capacity of the platform under the foundation. The three corners of the load upper platform and the foundation lower platform are provided with threaded holes, and the threaded holes are used to connect with the upper adapter or the lower adapter.

In the active vibration isolation unit of the present invention, the MFC sensor is used to receive the vibration interference signal of the load platform, and transmit it to the controller through the wire; It is transmitted to the MFC actuator; the real-time control signal drives the MFC actuator to generate the corresponding actuation force, and offsets the vibration interference signal to reduce the vibration of the load platform to achieve active vibration control.

The vibration isolation platform of the present invention is based on the Stewart configuration and adopts an active control method. Specifically, it includes the following steps:

(1) The sensor receives the vibration interference signal

The MFC sensor in the present invention is used to receive the vibration signal of the load platform under vibration interference. When the load platform vibrates and deforms, the MFC sensor will generate a corresponding amount of charge, which is proportional to the deformation of the load platform. Vibration disturbance signals p _i (i=1, . . . , 9) received by the MFC sensor are transmitted to the controller via wires.

(2) The controller calculates the vibration interference signal

The vibration interference signal transmitted from the MFC sensor to the controller will be calculated through the control algorithm, and the calculated output signal is the control signal of the actuator. The control signal calculated by the controller is transmitted to the MFC actuator via wires.

(3) Actuator output power

The control signal transmitted from the controller to the MFC actuator will drive the MFC actuator to generate corresponding actuation force, and the generated actuation force will offset the vibration interference signal to restore the load platform to its original state, thereby realizing the Stewart vibration isolation platform active control.

In the step of calculating the vibration interference signal by the controller, the control algorithm used may be PID control, adaptive RLS algorithm, adaptive LMS algorithm and the like.

PI integral force control comes from the classic control algorithm PID control, see the bibliography "Automatic Regulatory System Analysis and PID Tuning", written by Bai Zhigang, Beijing, Chemical Industry Press, 2012.

Adaptive RLS algorithm or adaptive LMS algorithm are both from "Adaptive Control", written by Chai Tianyou and Yue Heng, Beijing, Tsinghua University Press, 2016.

Compared with the prior art, the present invention has achieved the following technical effects:

The MFC used in the vibration isolation platform of the present invention has the characteristics of light weight, small size, fast response, high precision, large operating force, low rigidity, etc., and is easy to be bonded to various structures for convenient installation. The use of multiple MFCs can realize the active control and vibration reduction of the Stewart configuration vibration isolation platform. The sensors and actuators used are both MFCs. According to actual needs, each piece of MFC can realize role switching, and can be used as an MFC sensor or as an MFC. It can be used as an actuator without changing its original structure and position. It only needs to switch in the control loop according to the positive and negative effects of piezoelectricity to realize the role exchange of MFC, so that it can be used as an MFC sensor or an MFC actuator. The six single-leg vibration isolation units all contain compression spring negative stiffness structures to ensure that the stiffness of the six single-leg vibration isolation units is low, making the MFC actuator play a dominant role.

The vibration isolation platform of the present invention is divided into a passive vibration isolation unit and an active vibration isolation unit, and the load upper platform, the foundation lower platform, the single leg unit and the adapter jointly form the passive vibration isolation unit. The closed-loop control loop composed of MFC sensor, controller, MFC actuator and wire is the active control unit. The passive vibration isolation unit ensures the reliability of the vibration isolation performance. When the active vibration isolation unit fails, the vibration isolation platform still has a certain vibration isolation effect. The active vibration isolation unit improves the vibration isolation performance, so that the vibration isolation platform has good vibration isolation performance at low frequency resonance and high frequency.

Description of drawings

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

Fig. 1 is the overall structure schematic diagram of the Stewart vibration isolation platform based on MFC positive and negative piezoelectric effect of the present invention;

Fig. 2 is the structural schematic diagram of the single-leg vibration isolation unit of the Stewart vibration isolation platform based on the MFC forward and reverse piezoelectric effect in the present invention;

Fig. 3 is the schematic diagram of the compression spring type negative stiffness structure of the Stewart vibration isolation platform based on the MFC forward and reverse piezoelectric effect in the present invention;

Fig. 4 is the schematic diagram of the flexible hinge structure of the Stewart vibration isolation platform based on the forward and reverse piezoelectric effect of MFC in the present invention;

5 is a schematic diagram of the structure of the upper end cover of the Stewart vibration isolation platform based on the forward and reverse piezoelectric effect of MFC in the present invention;

Fig. 6 is a structural schematic diagram of the intermediate cage of the Stewart vibration isolation platform based on the MFC forward and reverse piezoelectric effect according to the present invention;

7 is a schematic diagram of the structure of the lower end cover of the Stewart vibration isolation platform based on the forward and reverse piezoelectric effect of MFC in the present invention;

Fig. 8 is a schematic diagram of the load platform structure of the Stewart vibration isolation platform based on the MFC forward and reverse piezoelectric effect in the present invention;

Fig. 9 is a schematic diagram of the basic platform structure of the Stewart vibration isolation platform based on the forward and reverse piezoelectric effect of MFC in the present invention;

Fig. 10 is a schematic diagram of the adapter structure of the Stewart vibration isolation platform based on the MFC forward and reverse piezoelectric effect according to the present invention;

11 is a schematic diagram of the geometric principle of the Stewart configuration in the Stewart vibration isolation platform based on the MFC forward and reverse piezoelectric effect in the present invention;

Figure 12(a) is a schematic diagram of the mechanism of action of a traditional passive vibration isolation platform;

Figure 12(b) is a schematic diagram of the action mechanism and control principle of the Stewart vibration isolation platform based on the MFC forward and reverse piezoelectric effect in the present invention;

Fig. 13 is a comparison chart of the transmissibility curves of the traditional vibration isolation platform, the passive vibration isolation of the present invention and the active control of the present invention;

Explanation of reference numerals: Stewart vibration isolation platform 100 based on MFC forward and reverse piezoelectric effect, load upper platform 1, upper adapter 2, first upper adapter 2a, second upper adapter 2b, third upper adapter 2c, Single leg vibration isolation unit 3, first single leg vibration isolation unit 3a, second single leg vibration isolation unit 3b, third single leg vibration isolation unit 3c, fourth single leg vibration isolation unit 3d, fifth single leg vibration isolation unit 3e, sixth single-leg vibration isolation unit 3f, upper flexible hinge 31a, lower flexible hinge 31b, upper end cover 32, connecting flange 321, middle cage 33, lower end cover 34, support rod 35, pressure spring 36, three-way steering Joint 37, lower adapter 4, first lower adapter 4a, second lower adapter 4b, third lower adapter 4c, foundation lower platform 5, controller 11, first MFC sensor 12, first MFC actuator 13. A second MFC sensor 14 , a second MFC actuator 15 , a third MFC sensor 16 , and a third MFC actuator 17 .

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The purpose of the present invention is to provide a Stewart vibration isolation platform based on MFC positive and negative piezoelectric effects to solve the problems in the prior art. The active and passive composite vibration reduction technology can reduce the resonance peak while ensuring high frequency The attenuation rate achieves a good vibration isolation effect, and the response is sensitive, safe and reliable.

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

Referring to accompanying drawings 1 to 11, the present invention provides a Stewart vibration isolation platform 100 based on the MFC direct and inverse piezoelectric effect, which includes a load upper platform 1 and a foundation lower platform 5 respectively in a triangular structure, and the load upper platform 1 The vertical projection of the three angles after the horizontal rotation of 120 degrees coincides with the vertical projection of the three angles of the platform 5 under the foundation. The three corners of the platform 1 on the load are respectively fixedly connected with an upper adapter 2, and the platform under the foundation The three corner positions of 5 are respectively connected with a lower adapter 4, and there are six single-leg vibration isolation units 3 connected between the three upper adapters 2 and three lower adapters 4, and the adjacent single-leg vibration isolation units 3 are perpendicular to each other, and the opposite single-leg vibration isolation units 3 are parallel to each other, and the overall shape is a cube, which is convenient for decoupling; each support beam of the load platform 1 is equipped with three pairs of MFC piezoelectric fiber patches, and each pair of MFC piezoelectric fiber patches Each patch includes an MFC sensor and an MFC actuator. Using the positive and negative effects of piezoelectricity, each MFC in each pair of MFC piezoelectric fiber patches can switch the roles of sensors and actuators according to actual needs. , only need to switch in the control loop according to the positive and negative effects of piezoelectricity. That is, each pair of MFC piezoelectric fiber patches in the present invention can be used as both an MFC sensor and an MFC actuator, and the same material/device can be realized. The actuators are electrically connected to the controller through wires, and multiple MFC sensors and MFC actuators are combined with the controller to realize the active control and vibration reduction of the Stewart configuration vibration isolation platform.

Specifically, the six single-leg vibration isolation units have the same structure; each single-leg vibration isolation unit 3 includes an upper end cover 32, a middle cage 33 and a lower end cover 34 fixedly connected in sequence, and the upper end cover 32, the middle cage 33 and the The end faces of the lower end cover 34 are respectively provided with symmetrical connecting threaded holes, and the connecting threaded holes are used to pass long bolts, and the upper end cover 32, the middle cage 33 and the lower end cover 34 are fixedly connected by long bolts; the upper end cover 32 A compression spring type negative stiffness structure is arranged inside, the top end of the compression spring type negative stiffness structure penetrates the upper end cover 32 and is connected with an upper end flexible hinge 31a, and the bottom of the lower end cover 34 is fixedly connected with a lower end flexible hinge 31b. Due to the existence of the compression spring type negative stiffness structure, each single-leg vibration isolation unit 3 exhibits negative stiffness within a certain stroke, making the overall stiffness softer to ensure that the actuating force of the MFC actuator can play a greater role .

Two connecting flanges 321 are fixedly arranged on the inner wall of the upper end cover 32; the compression spring type negative stiffness structure includes a three-way adapter 37, and the two ends of the three-way adapter 37 are located at the bottom respectively through the compression spring 36 and the inner wall of the upper end cover 32. The connection flange 321 is fixedly connected, and the upper end of the three-way adapter 37 is fixedly connected with a support rod 35 through a compression spring 36. The support rod 35 penetrates the top of the upper end cover 32 and is fixedly connected with the upper flexible hinge 31a. The upper flexible hinge 31a is connected to the support rod 35 through its own threaded rod and threaded hole, and then passes through the upper end cover 32 with a certain gap to ensure the axial freedom of the single-leg vibration isolation unit. The lower end cover 34 and the lower end flexible hinge 31b are connected through their own threaded rods and threaded holes without leaving a gap. When the external vibration interference is transmitted to the single-leg vibration isolation unit 3 through the platform 5 under the foundation, the compression spring negative stiffness structure will consume part of the energy due to the principle of negative stiffness, and the vibration interference signal transmitted to the load platform 1 is received by the MFC sensor. After the controller 11 processes the output control signal, it cancels out the driving force generated by the MFC actuator, thereby suppressing the vibration of the platform 1 on the load.

A connecting block is provided on the top side of the upper adapter 2, and two first connecting holes arranged in parallel are opened on the connecting block, and two symmetrical slopes are opened on the side of the upper adapter 2 close to the connecting block, and two symmetrical slopes are opened on the two slopes. There are two second connecting holes arranged vertically. The upper adapter 2 has the same structure as the lower adapter 4; the first connecting hole of the upper adapter 2 is fixedly connected to the upper platform of the load through screws, and the first connecting hole of the lower adapter 4 It is fixedly connected with platform 5 under the foundation by screws. The three upper transfer joints 2 are respectively the first upper transfer joint 2a, the second upper transfer joint 2b and the third upper transfer joint 2c, and the three lower transfer joints 4 are respectively the first lower transfer joint 4a and the second lower transfer joint 4b and the third lower adapter 4c; the six single-leg vibration isolation units 3 are respectively the first single-leg vibration isolation unit 3a, the second single-leg vibration isolation unit 3b, the third single-leg vibration isolation unit 3c, and the fourth single-leg vibration isolation unit vibration unit 3d, the fifth single-leg vibration isolation unit 3e and the sixth single-leg vibration isolation unit 3f; The upper end flexible hinge of the vibration isolation unit 3f is fixedly connected, and the two second connection holes of the second upper adapter 2b are respectively fixedly connected with the upper end flexible hinges of the second single-leg vibration isolation unit 3b and the third single-leg vibration isolation unit 3c, The two second connection holes of the third upper transfer joint 2c are fixedly connected with the upper end flexible hinges of the fourth single-leg vibration isolation unit 3d and the fifth single-leg vibration isolation unit 3e respectively; the two second connection holes of the first lower transfer joint 4a The connection holes are respectively fixedly connected with the flexible hinges at the lower end of the first single-leg vibration isolation unit 3a and the second single-leg vibration isolation unit 3b, and the two second connection holes of the second lower adapter 4b are respectively connected with the third single-leg vibration isolation unit 3c is fixedly connected to the lower end flexible hinge of the fourth single-leg vibration isolation unit 3d, and the two second connection holes of the third lower adapter 4c are respectively connected to the fifth single-leg vibration isolation unit 3e and the sixth single-leg vibration isolation unit 3f. The flexible hinge at the lower end is fixedly connected.

The three MFC sensors set on each support beam of the loading platform 1 are respectively the first MFC sensor 12, the second MFC sensor 14 and the third MFC sensor 16, and the three MFC actuators are respectively the first MFC actuator 13. The second MFC actuator 15 and the third MFC actuator 17; the first MFC sensor 12 and the first MFC actuator 13 are symmetrically arranged on the upper and lower surfaces of the supporting beam of the loading platform 1, and the second MFC The sensor 14 and the second MFC actuator 15 are symmetrically embedded in the cross section of the support beam of the upper platform 1 on the load, and the third MFC sensor 16 and the third MFC actuator 17 are symmetrically arranged on the upper and lower sides of the support beam of the upper platform 1 on the load. On the surface; the second MFC sensor 14 and the second MFC actuator 15 are located between the first MFC sensor 12 and the third MFC sensor 16 . Among them, the first MFC sensor 12 and the third MFC sensor 16 are used to receive the vibration interference signal in the longitudinal direction of the beam, and the second MFC sensor 14 is used to receive the vibration interference signal in the axial direction of the beam. The vibration interference signals received by the sensors together constitute the vibration condition of the load platform 1 . The first MFC actuator 13 and the third MFC actuator 17 are used to provide the actuating force on the longitudinal direction of the beam, and the second MFC actuator 15 is used to provide the actuating force on the axial direction of the beam. The actuating forces provided by the nine actuators work together to offset the external vibration interference signal, so that the vibration amplitude of the load platform 1 is reduced.

Preferably, the load upper platform 1 is an isosceles triangle structure, and the outer positions of the three corners of the load upper platform 1 are provided with horizontal connection end faces, the upper transfer joint 2 is fixedly arranged at the horizontal connection end faces, and the load upper platform 1 is provided with three One reinforcing rod, one end of the three reinforcing rods is respectively connected to a corner of the load upper platform 1, and is located on the bisector of the corner, and the other ends of the three reinforcing rods are fixedly connected at the center of the circumscribed circle of the load upper platform 1; The lower foundation platform 5 is an isosceles triangle structure, and the three corners of the lower foundation platform 5 are provided with horizontal connection end faces, the lower adapter 4 is fixedly arranged at the horizontal connection end faces, and three reinforcing rods are arranged inside the foundation lower platform 5 , one end of the three reinforcing rods is respectively connected to a corner of the platform 5 under the foundation, and is located on the bisector of the corner, and the other ends of the three reinforcing rods are fixedly connected at the center of the circumcircle of the platform 5 under the foundation. The width of the reinforcing bars of the platform 1 on the load is smaller than the width of the support beams of the platform 1 on the load; the width of the reinforcing bars of the platform 5 under the foundation is greater than the width of the support beams of the platform 5 under the foundation.

The three MFC sensors on each beam of the present invention, the controller 11 and the three MFC actuators form a closed-loop loop to play the role of active control vibration isolation. In the present invention, the load upper platform 1, the foundation lower platform 5, the single-leg vibration isolation unit 3, the upper adapter 2 and the lower adapter 4 together form a passive vibration isolation unit. When the active vibration isolation unit of the present invention is not working, the vibration isolation platform is equivalent to passive vibration isolation.

When the vibration isolation platform of the present invention is working, external vibration interference signals are transmitted from the platform under the foundation 5 to the single-leg vibration isolation unit 3, and the compression spring type negative stiffness structure in the single-leg vibration isolation unit 3 has the effect of a negative stiffness spring. Some energy can be consumed. The remaining energy is transmitted to the load platform 1 through the single-leg vibration isolation unit. In the active control loop, the MFC sensor receives the vibration interference signal of the load platform 1 and transmits it to the controller 11 for processing. The output of the controller 11 is real-time The control signal drives the MFC actuator to generate actuation force, and offsets the vibration interference signal of the platform 1 on the load to reduce the vibration of the platform 1 on the load.

As shown in Fig. 12(a), the passive vibration isolation platform can be equivalent to a mass-spring-damper system, and its transfer function is:

This formula belongs to the range of complex numbers, where X _i is the displacement response of the platform on the load after being subjected to the vibration interference signal, X ₀ is the excitation displacement of the platform under the foundation received by the vibration interference signal, M is the mass of the platform on the load, and C is the vibration isolation The equivalent damping of the platform, K is the equivalent stiffness of the vibration isolation platform.

As shown in Figure 12(b), the vibration isolation platform of the present invention is based on passive vibration isolation, adding an active control loop. In the active control loop, the vibration interference signal is received by the MFC sensor, and after being processed by the controller 11, the output control signal drives the MFC actuator to generate corresponding actuation force to suppress the vibration of the platform 1 on the load.

The example of the active control method of the present invention includes three steps: the sensor receives the vibration interference signal, the controller 11 calculates the vibration interference signal, and the actuator outputs the driving force. In the step of the sensor receiving the vibration interference signal, the MFC sensor receives the vibration deformation signal of the load platform, and converts it into a charge signal and transmits it to the controller; in the step of the controller 11 calculating the vibration interference signal, the controller 11 transmits the transmitted vibration deformation signal Through the control algorithm to process, the real-time control signal is obtained and transmitted to the MFC actuator; in the step of the actuator output power, the real-time control signal drives the MFC actuator to generate the corresponding power, which acts on the load platform. Dampens the vibration of the load platform.

As shown in FIG. 13 , the vertical axis is amplitude (db), and the horizontal axis is frequency (Hz). It can be seen from the comparison chart of the transmissibility curve that, compared with the traditional passive vibration isolation, the passive vibration isolation of the present invention reduces the resonance peak, moves the resonance frequency forward, improves high-frequency attenuation, widens the vibration isolation bandwidth, and improves the vibration isolation effect; When the vibration isolation platform of the present invention is added to the active control loop of the active vibration isolation of the present invention, the vibration isolation effect is further improved, and the resonance peak value is significantly improved.

In the description of the present invention, it should be noted that the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, or in a specific orientation. construction and operation, therefore, should not be construed as limiting the invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance.

In the present invention, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention; meanwhile, for those of ordinary skill in the art, according to the present invention The idea of the invention will have changes in the specific implementation and scope of application. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (7)

1. The utility model provides a Stewart vibration isolation platform based on MFC positive and negative piezoelectric effect which characterized in that: the vibration isolation device comprises a load upper platform and a base lower platform which are respectively in a triangular structure, wherein vertical projections of three angles of the load upper platform after the load upper platform horizontally rotates 120 degrees are superposed with vertical projections of three angles of the base lower platform, an upper rotating joint is fixedly connected to each of the three angular positions of the load upper platform, a lower rotating joint is connected to each of the three angular positions of the base lower platform, and six single-leg vibration isolation units are connected between the three upper rotating joints and the three lower rotating joints; each supporting beam of the upper loading platform is provided with three pairs of MFC piezoelectric fiber patches, each pair of MFC piezoelectric fiber patches comprises an MFC sensor and an MFC actuator, the MFC sensors and the MFC actuators in each pair of MFC piezoelectric fiber patches can be exchanged in roles, the MFC sensors and the MFC actuators are respectively and electrically connected with a controller through wires, and the plurality of MFC sensors and the MFC actuators are combined with the controller to realize active control of vibration reduction; the six single-leg vibration isolation units have the same structure; each single-leg vibration isolation unit comprises an upper end cover, a middle retainer and a lower end cover which are fixedly connected in sequence; a pressure spring type negative stiffness structure is arranged in the upper end cover, the top end of the pressure spring type negative stiffness structure penetrates through the upper end cover and is connected with an upper end flexible hinge, and the bottom of the lower end cover is fixedly connected with a lower end flexible hinge; two connecting flanges are fixedly arranged on the inner wall of the upper end cover; the pressure spring formula burden rigidity structure includes the three-way adapter, the both ends that the three-way adapter is located the below respectively through the pressure spring with connecting flange fixed connection on the upper end cover inner wall, the one end that the three-way adapter is located the top passes through pressure spring fixedly connected with bracing piece, the bracing piece runs through behind the upper end cover top with upper end flexible hinge fixed connection.

2. A Stewart vibration isolation platform based on MFC positive and negative piezoelectric effect in claim 1, wherein: a connecting block is arranged on one side of the top of the upper rotating joint, two first connecting holes which are arranged in parallel are formed in the connecting block, two symmetrical inclined planes are formed in one side, close to the connecting block, of the upper rotating joint, two second connecting holes which are vertically arranged are formed in the two inclined planes, and the upper rotating joint is identical to the lower rotating joint in structure; the first connecting hole of the upper rotary joint is fixedly connected with the load upper platform through a screw, and the first connecting hole of the lower rotary joint is fixedly connected with the foundation lower platform through a screw.

3. A Stewart vibration isolation platform based on MFC positive and negative piezoelectric effect in claim 2, wherein: the three upper rotary joints are respectively a first upper rotary joint, a second upper rotary joint and a third upper rotary joint, and the three lower rotary joints are respectively a first lower rotary joint, a second lower rotary joint and a third lower rotary joint; the six single-leg vibration isolation units are respectively a first single-leg vibration isolation unit, a second single-leg vibration isolation unit, a third single-leg vibration isolation unit, a fourth single-leg vibration isolation unit, a fifth single-leg vibration isolation unit and a sixth single-leg vibration isolation unit; the two second connecting holes of the first upper rotary joint are fixedly connected with the upper end flexible hinges of the first single-leg vibration isolation unit and the sixth single-leg vibration isolation unit respectively, the two second connecting holes of the second upper rotary joint are fixedly connected with the upper end flexible hinges of the second single-leg vibration isolation unit and the third single-leg vibration isolation unit respectively, and the two second connecting holes of the third upper rotary joint are fixedly connected with the upper end flexible hinges of the fourth single-leg vibration isolation unit and the fifth single-leg vibration isolation unit respectively; the two second connecting holes of the first lower adapter are fixedly connected with lower end flexible hinges of the first single-leg vibration isolation unit and the second single-leg vibration isolation unit respectively, the two second connecting holes of the second lower adapter are fixedly connected with lower end flexible hinges of the third single-leg vibration isolation unit and the fourth single-leg vibration isolation unit respectively, and the two second connecting holes of the third lower adapter are fixedly connected with lower end flexible hinges of the fifth single-leg vibration isolation unit and the sixth single-leg vibration isolation unit respectively.

4. A Stewart vibration isolation platform based on MFC positive and negative piezoelectric effect in claim 1, wherein: the three MFC sensors arranged on each supporting beam of the load upper platform are respectively a first MFC sensor, a second MFC sensor and a third MFC sensor, and the three MFC actuators are respectively a first MFC actuator, a second MFC actuator and a third MFC actuator; the first MFC sensor and the first MFC actuator are symmetrically arranged on the upper surface and the lower surface of the load upper platform support beam, the second MFC sensor and the second MFC actuator are symmetrically embedded in the cross section of the load upper platform, and the third MFC sensor and the third MFC actuator are symmetrically arranged on the upper surface and the lower surface of the load upper platform support beam; the second MFC sensor and second MFC actuator are located at a position between the first MFC sensor and third MFC sensor.

5. A Stewart vibration isolation platform based on MFC positive and negative piezoelectric effect in claim 1, wherein: the end faces of the upper end cover, the middle retainer and the lower end cover are respectively provided with symmetrical connecting threaded holes, long bolts penetrate through the connecting threaded holes, and the upper end cover, the middle retainer and the lower end cover are fixedly connected through the long bolts.

6. The Stewart vibration isolation platform based on MFC positive and reverse piezoelectric effect of claim 1, characterized in that: the load upper platform is of an isosceles triangle structure, horizontal connecting end faces are arranged at the outer sides of three corners of the load upper platform, the upper rotating joint is fixedly arranged at the horizontal connecting end faces, three reinforcing rods are arranged in the load upper platform, one ends of the three reinforcing rods are respectively connected with one corner of the load upper platform and are positioned on an bisector of the corner, and the other ends of the three reinforcing rods are fixedly connected at the position of the circle center of a circumscribed circle of the load upper platform; the base lower platform is of an isosceles triangle structure, a horizontal connection end face is arranged at the position of the outer side of three corners of the base lower platform, a lower rotary joint is fixedly arranged at the position of the horizontal connection end face, three reinforcing rods are arranged in the base lower platform, one end of each reinforcing rod is connected with one corner of the base lower platform and located on an equal dividing line of the corner, and the other end of each reinforcing rod is fixedly connected with the position of the circle center of an outer circle of the base lower platform.

7. A Stewart vibration isolation platform based on MFC positive and negative piezoelectric effect in claim 6, characterized in that: the width of the reinforcing rod of the load upper platform is smaller than that of the supporting beam of the load upper platform; the width of the reinforcing rod of the lower platform of the foundation is larger than that of the supporting beam of the lower platform of the foundation.

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