CN106321708B - A kind of compound active vibration insulator of two-freedom vibration isolation and precision positioning - Google Patents

Abstract

The invention discloses a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning. The vibration isolator includes a base platform (10) and a load platform (30). The vibration isolator also includes a vibration isolation unit. Between the base platform (10) and the load platform (30), the vibration isolation unit includes an air spring (20) and a first voice coil motor (25a) arranged along a first direction, and the vibration isolation unit also It includes an adjustable stiffness leaf spring and a second voice coil motor (25b) arranged along the second direction, and the vibration isolator also includes a positioning unit, which is arranged on the outside of the vibration isolation unit, and the positioning unit includes a The proportional pressure valve (26) is arranged in the direction, and the positioning unit also includes a second voice coil motor (25b) along the second direction. The vibration isolator of the present invention realizes precise vibration isolation and precise positioning through two vibration isolation units and a precise positioning unit, and is suitable for ultra-precision processing and measuring equipment in a micro environment.

Description

A Composite Active Vibration Isolator with Two Degrees of Freedom Vibration Isolation and Precise Positioning

technical field

The invention belongs to the field of ultra-vibration isolation and precise positioning, in particular to a composite active vibration isolator for two-degree-of-freedom vibration isolation and precise positioning.

Background technique

At present, in the field of high-end IC chip manufacturing and ultra-precision detection, the requirements for environmental micro-vibration isolation and precise positioning are becoming more and more stringent. The general ultra-precision shock absorber often only has the function of precision vibration isolation, and some high-end micro-motion platforms only have the function of precise positioning. Due to the need for vibration reduction, the positioning accuracy of some micro-motion platforms has been greatly attenuated, so some new technologies and methods are urgently needed to improve this situation. Some methods such as hydraulic cylinder + metal spring, piezoelectric actuator + spring diaphragm, voice coil motor + air spring can greatly improve the positioning and vibration reduction capabilities of this type of precision shock absorber.

The combination of hydraulic cylinder + metal spring can not only reduce the natural frequency of the system through the metal spring, but also improve the passive vibration isolation performance; as the active actuator, the hydraulic cylinder can also realize the active control of vibration isolation; at the same time, the hydraulic cylinder can also be used as an active positioning element. A certain degree of positioning. However, due to the low operating frequency of the hydraulic cylinder, its vibration reduction for medium and high frequencies is not obvious; at the same time, the combination of this mechanical structure leads to a large gap in the movement, which affects its positioning accuracy and positioning speed. The combination of piezoelectric actuator + spring diaphragm can also change the passive vibration isolation capability of the system through the diaphragm spring to achieve medium and high-frequency vibration suppression; At the same time, the piezoelectric actuator can also be used as a positioning actuator, which can realize nanometer-level positioning, but its entire motion stroke is only micron-level, which limits its use space. The combination of voice coil motor + air spring can realize the passive vibration isolation ability of medium and high frequency through the air spring, and the voice coil motor can realize the active vibration isolation ability of low frequency band as the active control actuator; The actuator can realize micron-level positioning and millimeter-level travel, which can not only ensure that the shock absorber has a large bearing capacity, but also effectively isolate ultra-low frequency vibrations and achieve precise positioning accuracy.

Patent document CN103318839A discloses a high-speed and high-precision macro-micro platform and switching method based on piezoelectric ceramics, which adopts 3 or more vibration isolators of static pressure air spring structure to support the air spring vibration isolation platform and its load, thereby Realize precise vibration damping of the structure. However, the high-speed and high-precision macro-micro platform based on piezoelectric ceramics disclosed in this patent document does not form a closed-loop position loop and cannot realize the function of precise positioning.

Contents of the invention

Aiming at the above defects or improvement needs of the prior art, the present invention provides a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning. The composite active vibration isolator has a compact The vibration isolation unit cooperates with different active control components to achieve precise vibration isolation and precise positioning in a micro-motion environment.

In order to achieve the above object, the present invention provides a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning, the vibration isolator includes a base platform and a load platform, the lower end of the base platform is connected to an external platform, the The upper end of the load platform is connected with the equipment requiring positioning and vibration isolation, which is characterized by:

The vibration isolator also includes a vibration isolation unit, which is arranged between the base platform and the load platform, one end is connected with the base platform, and the other end is connected with the load platform, and the vibration isolation unit includes The air spring and the first voice coil motor are provided, the air spring is used to realize the passive vibration isolation of the high frequency part, and the first voice coil motor is used to realize the active vibration isolation of the middle and low frequency, so as to realize the active and passive vibration in the first direction Composite full-band vibration isolation; the vibration isolation unit also includes an adjustable stiffness leaf spring and a second voice coil motor arranged along the second direction, and the leaf spring is connected to the air spring through a decoupling flexible hinge for realizing The passive vibration isolation of the high-frequency part, the second voice coil motor is used to realize the active vibration isolation of the middle and low frequencies, so as to realize the active-passive composite full-band vibration isolation in the second direction; and

A positioning unit is arranged on the outside of the vibration isolation unit, one end is connected to the base platform, and the other end is connected to the load platform, and the positioning unit includes a proportional pressure valve arranged along the first direction for controlling the The intake volume of the air spring can be adjusted to achieve precise positioning in the first direction; the positioning unit also includes a second voice coil motor arranged along the second direction for realizing displacement control, thereby realizing precise positioning in the second direction.

Further, the vibration isolation unit further includes a first speed sensor and a controller arranged along the first direction, the first speed sensor is used for the vibration speed signal of the load platform and transmitted to the controller, and the controller uses The active control signal is transmitted to the first voice coil motor through algorithm processing, so as to realize active vibration isolation at low and medium frequencies.

Further, the vibration isolation unit also includes a second speed sensor arranged along the second direction, the second speed sensor is used to collect the vibration speed signal of the load platform and transmit it to the controller, and the controller is used to pass the algorithm Processing and transmitting the active control signal to the second voice coil motor, so as to realize the active vibration isolation of the medium and low frequency in the second direction.

Further, the positioning unit also includes a first displacement sensor arranged along the first direction, the first displacement sensor is used to collect the displacement signal of the load platform and transmit it to the controller, and the controller is used to process the displacement signal through an algorithm And the active control signal is transmitted to the proportional pressure valve, and the proportional pressure valve controls the inflow and outflow of the air spring, so as to realize the precise positioning in the first direction.

Further, the positioning unit also includes a second displacement sensor arranged along the second direction, the second displacement sensor is used to collect the displacement signal of the load platform and transmit it to the controller, and the controller is used to process the displacement signal through an algorithm And the active control signal is transmitted to the second voice coil motor, and the second voice coil motor performs force-displacement control, thereby realizing precise positioning in the second direction.

Further, the air spring also includes a pressure valve, which is used to change the air pressure value of the input gas, and at the same time change the height value of the input gas through the proportional pressure valve, thereby changing the stiffness of the air spring in the first direction to adapt to different load environment.

Further, there are two leaf springs, namely the first leaf spring and the second leaf spring, and the first leaf spring and the second leaf spring form an angle of 90°, which is used to adjust the middle of each leaf spring. The stiffness adjustment mechanism is used to change the effective bending length of the leaf spring, thereby changing the stiffness in the second direction of the leaf spring.

Further, the first speed sensor and the second speed sensor are sensors capable of measuring absolute speed.

Further, the first displacement sensor and the second displacement sensor are non-contact displacement sensors.

Further, the first direction is the direction of the central axis of the foundation platform and the load platform, and the second direction is a direction perpendicular to the central axis.

The compound active vibration isolator with two degrees of freedom vibration isolation and precise positioning provided by the present invention is applied in the field of ultra-precision positioning and ultra-precision vibration isolation, overcomes the shortcomings of general vibration isolators that cannot or is difficult to achieve composite control, and is suitable for microenvironment Motion-sensitive ultra-precision machining and measuring equipment. Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

(1) The two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator of the present invention uses two separate precision positioning and precision vibration isolation units to cooperate with different active control elements to achieve precise positioning in a micro-motion environment and precision vibration isolation;

(2) The compound active vibration isolator with two degrees of freedom vibration isolation and precise positioning of the present invention realizes independent precision vibration isolation and precise positioning of two degrees of freedom through different active closed-loop control elements in the first direction and the second direction. position;

(3) The compound active vibration isolator with two degrees of freedom vibration isolation and precise positioning of the present invention adopts active and passive composite vibration isolation control for precision vibration isolation, which can realize active control of precision vibration isolation, and can not only effectively attenuate through passive components Medium and high frequency vibration, and the attenuation near the resonance peak can be achieved through active components.

(4) In the compound active vibration isolator with two degrees of freedom and precise positioning of the present invention, the stiffness of the air spring in the first direction can be adjusted, and the air pressure value of the input can be controlled to be different from the height of the cavity, thereby changing the air spring Vertical stiffness, adapt to different vertical loads.

(5) In the compound active vibration isolator with two degrees of freedom vibration isolation and precise positioning of the present invention, the stiffness of the leaf spring in the second direction can be adjusted, and the stiffness adjustment mechanism in the middle of each leaf spring can be adjusted to change the stiffness of the leaf spring. The effective bending length of the leaf spring changes the stiffness of the second direction of the leaf spring to adapt to different load environments.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning according to an embodiment of the present invention;

Fig. 2 is a partial structural schematic diagram of a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention;

Fig. 3 is a structural exploded diagram of a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning according to an embodiment of the present invention;

Fig. 4 is a three-dimensional view behind the load platform involved in a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention;

Fig. 5 is a front view of a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning according to an embodiment of the present invention;

Fig. 6 is a top view of a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning according to an embodiment of the present invention;

Fig. 7 is a simplified schematic diagram of the structure of an air spring involved in a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention;

Fig. 8 is a schematic diagram of the three-dimensional structure and orthogonal installation of the leaf spring involved in a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention;

Fig. 9 is a block diagram of a composite control of vibration isolation and precise positioning involved in a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention;

Fig. 10 is a block diagram of precise positioning control involved in a composite active vibration isolator with two degrees of freedom vibration isolation and precise positioning according to an embodiment of the present invention;

Fig. 11 is a schematic diagram of precision active vibration isolation involved in a two-degree-of-freedom vibration isolation and precision positioning composite active vibration isolator according to an embodiment of the present invention;

Fig. 12 is an effect diagram of precision active vibration isolation transmissibility involved in a two-degree-of-freedom vibration isolation and precision positioning composite active vibration isolator according to an embodiment of the present invention.

In Figures 1 to 6, the same reference numerals are used to represent the same components or structures, wherein: 10-basic platform, 20-air spring, 211-first leaf spring, 212-second leaf spring, 221-the first A locking screw structure, 222-second locking screw structure, 223-third locking screw structure, 231-first decoupling flexible hinge, 232-second decoupling flexible hinge, 24a-first speed sensor, 24b -Second speed sensor, 25a-First voice coil motor, 25b-Second voice coil motor, 26-Proportional pressure valve, 27a-First displacement sensor, 27b-Second displacement sensor, 30-Load platform, 40-Active controller.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

1 to 6 are structural schematic diagrams of a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator provided by the present invention. As shown in Figures 1 to 6, the vibration isolator includes a base platform 10, a load platform 30, a first voice coil motor 25a, a first speed sensor 24a, a first displacement sensor 27a, two mutually orthogonal horizontally adjustable Stiffness of the first leaf spring 211, the second leaf spring 212, the second voice coil motor 25b, the second speed sensor 24b, the second displacement sensor 27b, the air spring 20, the proportional pressure valve 26, the first leaf spring 211, the second The first decoupling flexible hinge 231, the second decoupling flexible hinge 232 of the two-plate spring 212 and the air spring 20, and the first locking screw structure 221 and the second locking screw structure connecting the base platform 10 and the load platform 30 222 and the third locking screw structure 223.

In a preferred embodiment of the invention, the first voice coil motor 25a and the second voice coil motor 25b are Lorentz motors.

In the preferred embodiment of the invention, the first speed sensor 24a and the second speed sensor 24b are Geophone absolute speed sensors.

In a preferred embodiment of the invention, the first displacement sensor 27a and the second displacement sensor 27b are non-contact eddy current displacement sensors.

As shown in Figures 1 to 4, the lower end of the air spring 20 is mounted on the foundation platform 10 by screws, and the center of the upper end is connected to the first decoupling flexible hinge 231 and the second decoupling flexible hinge 232 by fastening screws. One end is connected, and the other end of the first decoupling flexible hinge 231 and the second decoupling flexible hinge 232 are connected to the first leaf spring 211 and the second leaf spring 212 with adjustable stiffness through screws.

The first leaf spring 211 and the second leaf spring 212 are attached to the first locking screw structure 221 , the second locking screw structure 222 and the third locking screw structure 223 that connect and support the load platform 30 and the foundation platform 10 . Among them, the first locking screw structure 221 and the second locking screw structure 222 are installed orthogonally at an angle of 90°, and the third locking screw structure 223 is installed between the first locking screw structure 221 and the second locking screw structure 222. and installed at the other end of the air spring 20 on the mid-perpendicular line. At the same time, the proportional pressure valve 26 is also attached to one side of the third locking screw structure 223 by screws, and realizes the control of air in and out of the air spring through the air circuit. On the other side of the third locking screw structure 223, the second displacement sensor 27a is mounted on it through a mechanical structure.

As shown in Figures 1 to 4, the first displacement sensor 27a and the first voice coil motor 25a are also installed on the base platform 10 and the load platform 30 accordingly, wherein the stator of the first voice coil motor 25a is fixed on the base platform 10 , the mover of the first voice coil motor 25a is installed on the load platform 30 . The first speed sensor 24a is installed on the load platform 30, and its direction is parallel to the direction of the first displacement sensor 27a and the first voice coil motor 25a.

The second speed sensor 24b is installed on the load platform 30, and its installation direction is guaranteed to be perpendicular to the direction of the first displacement sensor 27a and the first direction voice coil motor 25a. The second voice coil motor 25b is correspondingly installed near the first speed sensor 24b. Wherein, the stator of the second voice coil motor 25 b is also installed and fixed on the base platform 10 , and the mover of the second voice coil motor 25 b is fixed on the load platform 30 . At the stator installation place of the second voice coil motor 25b, the second displacement sensor 27b is installed on the stator structure through a mechanical structure.

The displacement signal in the first direction and the displacement signal in the second direction are collected by the second displacement sensor 27b and the second displacement sensor 27a, and then output to the active controller 40 for active positioning algorithm calculation, and the calculated control signal is output to the proportional pressure valve 26 and the second voice coil motor 25b to perform closed-loop active positioning control.

The speed signal in the first direction and the speed signal in the second direction are collected by the first speed sensor 24b and the second speed sensor 24a, and output to the active controller 40 for active vibration isolation algorithm calculation, and the calculated control signal is output to the first voice coil The motor 25a and the second voice coil motor 25b perform closed-loop active vibration isolation control.

Fig. 5 is a front view of a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention. As shown in Figure 5, from left to right are the first voice coil motor 25a, the first displacement sensor 27a, the first speed sensor 24a, the proportional pressure valve 26, the first locking screw structure 221, and the second locking screw structure 222, the third locking screw structure 223, the second displacement sensor 27b, the second speed sensor 24b and the second voice coil motor 25b, wherein the first locking screw structure 221, the second locking screw structure 222 and the third locking screw structure The screw structure 223 is installed on the base platform 10 to support the load platform 30 .

Fig. 6 is a top view of a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention. As shown in Figure 6, the first locking screw structure 221 and the second locking screw structure 222 are installed perpendicularly at an angle of 90 degrees, while the vertical line is defined as the horizontal direction, and the third locking screw structure 223 is installed at the second A locking screw structure 221 and a second locking screw structure 222 are on the perpendicular line and at the other end of the air spring 20 .

Fig. 7 is a simplified schematic diagram of the structure of an air spring involved in a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention. As shown in FIG. 7 , the bottom plate 203 is fixed on the base platform 10 , and the sealing film 202 is used to connect the bottom plate 203 with the outer metal cavity 201 of the air spring 20 to form an air cavity 204 . The stiffness formula of the air cavity 204 is as follows:

It can be seen from formula (1) that the stiffness K of the single-chamber air spring is related to the load mass m, the cross-sectional area of the air chamber A, the volume of the air chamber V ₀ and the air pressure P _atm , and κ is the thermal insulation coefficient. In actual use, the air pressure of the inflated gas and the volume of the air spring cavity 204 can be controlled by the air valve to adjust different stiffnesses to adapt to different loads and usage conditions.

Fig. 8 is a schematic diagram of the three-dimensional structure and orthogonal installation of the leaf spring involved in a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention. In Fig. 8 (a), the metal dome 2111 and the metal dome 2113 are installed on the dome fixing device 2114 of the first leaf spring 211 and the second leaf spring 212 with horizontally adjustable stiffness, and the stiffness adjustment mechanism 2112 changes the metal dome by sliding up and down. The effective working bending length of the shrapnel 2111, 2113 changes the effective working stiffness of the metal shrapnel 2111, 2113, and further changes the stiffness of the first spring 211 and the second spring 212 with adjustable stiffness. At the same time, in order to be able to decouple the horizontal stiffness of the linear adjustment system, two springs with adjustable stiffness, the first leaf spring 211 and the second leaf spring 212, are orthogonally arranged at an angle of 90 degrees. The working principle is shown in Figure 8(b), and its mathematical The model derivation process is as follows:

The mechanism of two adjustable stiffness first leaf springs 211 and second leaf springs 212 arranged at 90° to each other can be equivalent to that shown in FIG. 8( b ). Point A in the figure is the action point of the force. Considering the generality, when a unit force F in any direction (θ is any value) acts on point A, the leaf spring mechanism will produce static deformation Δx in the direction of the force F to point B. The static displacements produced by the component force of unit force F on spring k ₁ and k ₂ are respectively

Assuming that the acting force is small, the resulting static deformation is also very small, so ∠CBD is still approximately a right angle, so the total deformation Δx is:

The spring stiffness k ₁ and k ₂ are the same, both are k, then the total stiffness of the mechanism in the θ direction can be expressed as

When two leaf springs are connected in parallel, the stiffness is twice that of one leaf spring, namely

k _and = 2k (5)

In a precision vibration isolation system, the vibration amplitude is usually at the micron level, which ensures the correctness of the above assumptions. In addition, due to the arbitrariness of θ, the stiffness of the mechanism in any direction remains consistent, which is the stiffness k of the first leaf spring 211 with adjustable stiffness.

According to the knowledge of material mechanics, the bending stiffness of the first leaf spring 211 and the second leaf spring 212 with adjustable stiffness of a rectangular section with one end fixed and one end free can be expressed as:

k _s =3EI/L (6)

Among them, E is the elastic modulus of the leaf spring material, I is the bending section moment of inertia, and L is the effective bending length of the leaf spring. It can be seen from the stiffness formula that the stiffness is inversely proportional to the effective bending length, so the stiffness can be changed by adjusting the effective bending length of the leaf spring, thereby realizing the adjustment of the stiffness in the second direction.

Fig. 9 is a block diagram of a composite control of vibration isolation and precise positioning involved in a two-degree-of-freedom vibration isolation and precise positioning composite active vibration isolator according to an embodiment of the present invention. As shown in Figure 9, the control block diagram is divided into a position loop that can control precise positioning and a speed loop that can achieve precise vibration isolation. Finally, the two loops are combined into a composite control of vibration isolation and precise positioning through parallel connection.

First set a displacement value, that is, the displacement place that precise positioning needs to achieve, then the actual displacement value at this time is collected by the first displacement sensor 27a and the second displacement sensor 27b, and the clutter noise signal is filtered by a low-pass filter After being filtered out, it is compared with the set value, and the error generated by the two signals enters the position controller 40 for active algorithm control, and outputs the data processed by the algorithm to the corresponding position actuator to realize closed-loop active positioning control.

After the first speed sensor 24a and the second speed sensor 24b collect the vibration speed signal of the load platform, the signal passes through a band-pass filter to filter out the useless clutter signal, and then transmits the useful speed signal to the feedback vibration isolation controller 40. After the control algorithm is processed, the data processed by the algorithm is output to the first voice coil motor 25a to realize closed-loop active vibration isolation control.

In a preferred implementation of the invention, a skyhook damping control algorithm is employed.

Fig. 10 is a block diagram of precision positioning control involved in a two-degree-of-freedom vibration isolation and precision positioning composite active vibration isolator according to an embodiment of the present invention. Fig. 10(a) is a vertical position loop control block diagram, as shown in Fig. 10(a), a vertical position setting value is first given, that is, the displacement required for precise positioning, and then passed through the first displacement sensor 27a The actual displacement value at this time is collected, and after the clutter noise signal is filtered out by a low-pass filter, it is compared with the set value, and the error produced by the two signals enters the position controller 40 for active algorithm control, and the The data processed by the algorithm is output to the proportional pressure valve 26 for active positioning control of the vibration isolation system to realize closed-loop active positioning control in the first direction.

In a preferred embodiment of the invention, a PID control algorithm with a second-order low-pass filter is used.

(b) of FIG. 10 is a block diagram of the horizontal position loop control. As shown in (b) of Figure 10, a horizontal position setting value is first given, that is, the displacement place that precise positioning needs to achieve, and then the actual displacement value at this time is collected by the second direction displacement sensor 27b, and obtained through a After the clutter noise signal is filtered out by the low-pass filter, it is compared with the set value, and the error generated by the two signals enters the position controller 40 for active algorithm control, and outputs the data processed by the algorithm to the second voice coil motor 25b , carry out the active positioning control vibration isolation system, and realize the closed-loop active positioning control in the second direction.

In a preferred embodiment of the invention, a PID control algorithm with a second-order low-pass filter is used.

In a preferred embodiment of the invention a Lorentz motor is used.

In the design of the positioning controller, this example adopts the control structure of connecting the PID controller and the second-order low-pass filter in series. The second-order low-pass filter filters the position signal to eliminate the influence of high-frequency noise in the position signal. The transfer function of the PID controller with the second-order low-pass filter in series can be expressed as:

In the formula, kp, ki and kd are the proportional coefficient, integral coefficient and differential coefficient of the PID controller respectively, flp and ξ are the cut-off frequency and damping coefficient of the second-order low-pass filter respectively, s=jω is the complex of Laplace transform variable, ω is the frequency domain coefficient, and j is the complex number unit.

The air spring and leaf spring passive vibration isolation mechanism adopted in the present invention are compared with the ceiling damping active vibration isolation control and the vibration isolation principle of the traditional vibration isolation mechanism as follows:

Fig. 11 is a schematic diagram of precision active vibration isolation involved in a two-degree-of-freedom vibration isolation and precision positioning composite active vibration isolator according to an embodiment of the present invention. As shown in (a) and (b) of Figure 11, both the traditional passive vibration isolation mechanism and the passive vibration isolation mechanism adopted by the present invention are composed of spring-mass-damping units to realize simple passive vibration isolation, and the transmissibility Curve function:

In the formula, x ₁ is the vibration displacement of the load platform, x ₀ is the vibration displacement of the foundation platform, C ₀ is the equivalent damping of the traditional passive mechanism, C is the equivalent damping of the mechanism adopted in the present invention, K ₀ is the traditional passive The equivalent stiffness between the mechanism load platform and the base platform, K is the equivalent stiffness between the mechanism load platform and the base platform adopted by the present invention, M is the quality of the load platform, s=jω is the complex variable of the Laplace transform, and ω is the frequency domain coefficient.

Compared with the traditional passive mechanism, the passive vibration isolation element used in the present invention is an air spring in the vertical direction and a leaf spring in the horizontal direction, and its stiffness value is much lower than that of the traditional passive mechanism, which can greatly reduce the natural frequency of the system.

As shown in (c) of Figure 11, the present invention adds an active feedback control loop on the basis of the passive vibration isolation mechanism. The active feedback control loop adopts the mode operation of sensor feedback, controller calculation, and actuator output to form Active and passive composite vibration isolation mechanism,

Taking the vibration signal on the load platform as a reference, the passive vibration isolation unit is actively controlled (the skyhook damping feedback control algorithm is used in this embodiment) to form an active and passive composite vibration isolation unit, where the control force F is:

F＝λx ₁ s (10)

In the above formula, λ is the gain coefficient of skyhook damping, s=jω is the complex variable of Laplace transform, and ω is the frequency domain coefficient.

Then the transmissibility curve function G _C under the closed-loop condition of the active-passive composite vibration isolation mechanism:

Fig. 12 is an effect diagram of precision active vibration isolation transmissibility involved in a two-degree-of-freedom vibration isolation and precision positioning composite active vibration isolator according to an embodiment of the present invention. It can be seen from the solid line in the figure that when the traditional passive mechanism is used for vibration isolation, its natural frequency is higher and the amplitude of the resonance peak is larger. After adopting this structure, it can be seen from the dotted line in the figure that the passive transmissibility is partially attenuated at the low-frequency formant, and the natural frequency is shifted forward. It can be seen from the dotted line in the figure that after adopting the active vibration isolation control of the present invention, the damping is further improved and the resonance peak of the system is also compensated by the actively controlled ceiling damping. From the transmissibility curve of the system, it can be seen that this The invention further improves the vibration suppression ability.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (10)

1. a kind of two-freedom vibration isolation and the compound active vibration insulator of precision positioning, the vibration isolator includes basic platform (10) and born Carrying platform (30), the lower end of the basic platform (10) are connected with outside platform, the upper end of the load platform (30) and needs Positioning connects with the equipment of vibration isolation, it is characterised in that：

The vibration isolator also includes vibration isolation unit, and it is arranged between the basic platform (10) and load platform (30), one end with Basic platform (10) connection, the other end are connected with the load platform (30), and the vibration isolation unit is included in the first direction The air spring (20) and the first voice coil motor (25a) of setting, the air spring are used for the passive vibration isolation for realizing HFS, First voice coil motor be used for realize in low frequency active vibration isolation, so as to realize the active-passive composite full frequency band of first direction every Shake；The vibration isolation unit also includes the adjustable rigidity flat spring and the second voice coil motor (25b) that set in a second direction, described Spring is connected by decoupling flexible hinge with the air spring, for realizing the passive vibration isolation of HFS, second sound Enclose motor and be used for low frequency active vibration isolation in realizing, so as to realize the active-passive composite full frequency band vibration isolation of second direction；And

Positioning unit, it is arranged on the outside of the vibration isolation unit, and one end is connected with the basic platform (10), the other end and institute Load platform (30) connection is stated, the positioning unit includes the proportional pressure valve (26) set in the first direction, for controlling Air spring (20) air inflow is stated, so as to realize the precision positioning of first direction；The positioning unit is also included in a second direction Second voice coil motor (25b) is set to obtain, for realizing Bit andits control, so as to realize the precision positioning of second direction.

2. a kind of two-freedom vibration isolation according to claim 1 and the compound active vibration insulator of precision positioning, its feature exist In：The vibration isolation unit also includes the First Speed sensor (24a) and controller (40) that set in the first direction, and described first Velocity sensor is used for the vibration velocity signal of the load platform (30) and is transferred to the controller (40), controller (40) For active control signal to be passed into first voice coil motor (25a) by algorithm process disease, so as to low frequency master in realizing Dynamic vibration isolation.

3. a kind of two-freedom vibration isolation according to claim 2 and the compound active vibration insulator of precision positioning, its feature exist In：The vibration isolation unit also includes the second speed sensor (24b) set in a second direction, and the second speed sensor is used The controller (40) is transferred in the vibration velocity signal for gathering the load platform (30), controller (40) is used to pass through calculation Method handle simultaneously active control signal is passed into second voice coil motor (25b), realize second direction middle low frequency actively every Shake.

4. a kind of two-freedom vibration isolation according to claim 1 and the compound active vibration insulator of precision positioning, its feature exist In：The positioning unit also includes the first displacement transducer (27a) set in the first direction, and first displacement transducer is used In the displacement signal for gathering the load platform (30) and the controller (40) is transferred to, controller (40) is used to pass through algorithm Handle and active control signal is passed into the proportional pressure valve (26), the system of air spring (20) described in proportional pressure valve control Enter gas output, so as to realize the precision positioning of first direction.

5. a kind of two-freedom vibration isolation according to claim 4 and the compound active vibration insulator of precision positioning, its feature exist In：The positioning unit also includes the second displacement sensor (27b) set in a second direction, and the second displacement sensor is used In the displacement signal for gathering the load platform (30) and the controller (40) is transferred to, controller (40) is used to pass through algorithm Handle and active control signal is passed into second voice coil motor (25b), second voice coil motor (25b) carries out power position Control is moved, so as to realize the precision positioning of second direction.

6. a kind of two-freedom vibration isolation according to claim 1 and the compound active vibration insulator of precision positioning, its feature exist In：The air spring (20) also includes pressure valve, for changing the atmospheric pressure value of input gas, while passes through the ratio pressure Valve (26) changes the height value of input gas, so as to change the rigidity of the air spring (20) first direction, to adapt to difference Load environment.

7. a kind of two-freedom vibration isolation according to claim 1 and the compound active vibration insulator of precision positioning, its feature exist In：The flat spring is two, respectively the first flat spring (211) and the second flat spring (212), first flat spring (211) and the second flat spring (212) angle in 90 °, for the stiffness tuning mechanism of the centre by adjusting each flat spring, with Change effective bending length of the flat spring, so as to change the second direction rigidity of the flat spring.

8. a kind of two-freedom vibration isolation according to claim 3 and the compound active vibration insulator of precision positioning, its feature exist In：The First Speed sensor (24a) and second speed sensor (24b) are the sensor that can measure absolute velocity.

9. a kind of two-freedom vibration isolation according to claim 5 and the compound active vibration insulator of precision positioning, its feature exist In：First displacement transducer (27a) and second displacement sensor (27b) are non-contact displacement transducer.

10. the compound active vibration isolation of a kind of the two-freedom vibration isolation and precision positioning according to any one of claim 1-9 Device, it is characterised in that：The first direction is the central axial direction of the basic platform (10) and load platform (30), described Second direction is the direction with the central axis upright.