JP2886053B2 - Active anti-vibration apparatus and control method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to
The present invention relates to an active anti-vibration device and a control method thereof, which can improve the vibration damping performance without impairing the anti-vibration effect and can easily design and adjust the control parameters.

[0002]

2. Description of the Related Art As precision instruments such as an electron microscope and a semiconductor exposure apparatus have become more precise, there has been a demand for higher performance of a precision anti-vibration apparatus equipped with them. In particular, in a semiconductor exposure apparatus, in order to perform appropriate and rapid exposure, a vibration isolation table for removing vibration transmitted from the outside such as installation floor vibration as much as possible is required. This is because the exposure of the semiconductor needs to be performed with the exposure XY stage completely stopped.
Further, the exposure XY stage is characterized by an intermittent operation called step & repeat, and repeated step vibrations cause vibration of the vibration isolation table itself. Therefore, it is required for the precision vibration isolation table to simultaneously achieve vibration isolation for external vibration and vibration suppression for vibration caused by the operation of the device itself.

In response to such a demand, an active vibration isolator has recently been put into practical use that compensates for an output signal of a vibration sensor attached to a vibration isolation table and feeds it back to an actuator to actively control vibration. . The active vibration isolation device enables simultaneous realization of vibration isolation and vibration suppression, which has been difficult with a passive vibration isolation device including only a spring and a damper.

In a conventional active vibration isolator, a vibration sensor generally disposed on a vibration isolation table and an actuator and a control arithmetic unit disposed closest thereto are used to independently control each sensor / actuator pair. Have been adopted. That is, a method has been adopted in which an independent control loop is formed in each part of the vibration isolation table.

However, in this method, it is difficult to grasp the characteristics of the entire vibration isolating table as a rigid body. Therefore, it is not easy to design and adjust the control parameters with good visibility while paying attention to the stability of the control system. In addition, in this method, since the motion of the rigid body of the vibration isolation table as a whole is not considered, not only the control system independently configured in each part of the vibration isolation table interferes, but also it is difficult to adjust the control parameters, It was not easy to improve the vibration control performance.

To solve such a problem, for example, Japanese Patent Application No. Hei.
Extract information of each motion mode of the vibration isolation table from the output of the vibration sensor as in -2999086 [control device of vibration isolation table]
It is effective to perform a control operation independently for each exercise mode. An active vibration isolation device that performs control calculations independently for each motion mode of the vibration isolation table is obtained by extracting information on each motion mode of the vibration isolation table from the output of the vibration sensor and performing control computation for each motion mode. The operation amount is fed back to each actuator using a thrust distribution calculation device. In this active vibration isolator, the design and adjustment of control parameters, which have been performed largely depending on trial and error for each control loop of each part of the vibration isolator, are now focused on the motion mode of the vibration isolator. The control system can be easily and rationally designed because the overall performance is taken into consideration.

[0007]

However, even when a non-interfering control system is constructed by paying attention to each motion mode in the control arithmetic unit, the respective motion modes of translation and rotation of the anti-vibration table to be controlled are mutually different. In the case of interference, the characteristics of the entire rigid body of the active vibration isolation device, that is, the closed-loop characteristics become an interference system, so it is necessary to pay attention to the characteristics of the entire control system and design and adjust the control parameters with good visibility. It will be difficult. In other words, even when the control operation is independently performed for each motion mode based on the information of each motion mode extracted by the control operation device, the motion of the anti-vibration table itself to be controlled interferes with each motion mode. In this case, the characteristics of the control system as a whole, such as the compliance characteristics and the vibration transmissibility that indicates the degree of transmission of the installed floor vibration to the device body vibration, cannot be handled independently for each motion mode. In designing and adjusting control parameters, it is necessary to consider interference with other motion modes.

[0008] For this reason, the ease of control parameter design and adjustment, which is a feature of the system in which the control operation is independently performed for each motion mode, is impaired.

Further, the control performance of the active anti-vibration device is impaired due to the interference between the motion modes of the anti-vibration table itself.

Therefore, it is desirable to design the anti-vibration table to be controlled so that each motion mode is non-interfering.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides an active vibration isolator and a control method thereof which facilitate design and adjustment of control parameters and facilitate improvement of control performance. The purpose is to:

[0012]

According to the present invention, there is provided a vibration isolator having a flat plate shape, and four corners of a rectangle or a square in a horizontal plane having a center of gravity of the vibration isolator as a diagonal intersection. A support means disposed at a position and having the same spring constant and viscous damping coefficient in the same direction among two directions parallel to two orthogonal sides of the rectangle or square;
A plurality of actuators arranged along two directions parallel to two orthogonal sides of a rectangle or a square in the horizontal plane, and a plurality of vibration sensors for detecting vibration of the vibration isolation table;
A motion mode extraction arithmetic unit for extracting information on each translational and rotational motion mode of the vibration isolation table from the output of each vibration sensor; and independently controlling each motion mode based on the output of the motion mode extraction arithmetic device. A non-interference control operation device for performing an operation, and a thrust distribution operation device for distributing a thrust to each actuator from an output of the non-interference control operation device. In order to extract motion mode information of three degrees of freedom of translational two degrees of freedom and one degree of rotation in the horizontal plane of the anti-vibration table in any of the above-described active anti-vibration devices and those including a spring and a viscous damper, Three vibration sensors
At least one in each of two directions parallel to two orthogonal sides of the rectangle or the square in the horizontal plane, vibration sensors that detect vibration in the same direction are arranged so as not to be aligned on the same straight line in the detection direction, Further, in order to control the three-degree-of-freedom motion mode, at least three actuators act in the same direction, at least one in at least two directions parallel to two orthogonal sides of a rectangle or a square in the horizontal plane. It is conceivable that the actuators are arranged so that they do not line up on the same straight line in the direction of action.

[0013] Further, an actuator using a voice coil motor as the actuator is conceivable.

In the control method of the active vibration isolator, each of the motion modes having three degrees of freedom in the horizontal plane of the vibration isolation table supported by the support means may be obtained by outputting information of each motion mode from an output of a vibration sensor. An arithmetic unit for extraction is used to perform the control operation independently for each motion mode using the non-interference control arithmetic unit, and each actuator is controlled using the arithmetic unit for distributing thrust to each actuator. Thereby, the motion mode of the vibration isolation table with three degrees of freedom in the horizontal plane is independently controlled, and the control parameters of the control arithmetic unit are designed and adjusted for each motion mode of the vibration isolation table.

[0015]

According to the present invention constructed as described above, it is possible to eliminate interference between translational and rotational motion modes in the horizontal plane of the vibration isolation table itself. That is, the translational force acting on the vibration isolation table is not transmitted to the rotation mode. By independently compensating for each motion mode using the above-described non-interference control arithmetic device or the like, the characteristics of the entire control system can be made non-interference, and the design and adjustment of the control parameters can be made very easily. , Can be easily performed. In other words, since each motion mode of the control system is completely non-interfering, the design and adjustment of control parameters are performed by focusing only on each motion mode without considering the influence of vibration from other motion modes. It becomes possible. In the installation of the active anti-vibration device, it is necessary to perform many adjustments such as control parameters, and the conventional control method has spent a lot of time, but the present invention makes this work very easy. It becomes possible. In addition, in the present invention, there is no interference between the motion modes in the vibration isolation table itself, so it is not necessary to consider an undesirable effect on the vibration control acting on each motion mode,
Even when a relatively simple control operation device is used, the control performance of the active vibration isolation device can be easily improved.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram best illustrating the configuration of an embodiment of the active vibration isolator of the present invention. In FIG.
x and y represent the absolute displacement of the translation mode among the motion modes in the horizontal plane, and θ _z represents the absolute displacement of the rotation mode around the vertical axis passing through the center of gravity G of the vibration isolation table. The coordinate system takes translations x and y so as to be orthogonal to each other in the horizontal direction as shown in FIG. 1 with the center of gravity G of the vibration isolation table as the origin.

In the present invention, the horizontal x is set at the four corners of a rectangle or square having the center of gravity G of the vibration isolation table 1 as the intersection of the diagonal lines.
2a, 2b, 2c, 2d in the direction and 3a, 3 in the y direction
The supporting means b, 3c and 3d are arranged. Support means 2
For a, 2b, 2c, 2d and 3a, 3b, 3c, 3d, those having the same spring constant and the same viscous damping coefficient in the same direction of x and y are used. Each support means comprises, for example, an air spring and a viscous damper. The vibration of the vibration isolation table 1 having such a configuration is transmitted to a vibration sensor 6 such as an acceleration sensor.
a, 6b, and 6c, and information of each exercise mode is extracted from the output using the exercise mode extraction arithmetic unit 7. Then, compensation is performed using the non-interference control calculation devices 8a, 8b, 8c that perform control calculation independently for each motion mode based on the extracted information on each motion mode. The manipulated variables obtained by the non-interference control calculation devices 8a, 8b, 8c are converted into the respective actuators 4 by using the thrust distribution calculation device 9.
a, 4b, 4c, 4d and 5a, 5b, 5c, 5d.

In the present invention, x, y are set at four corners of a rectangle or a square having the center of gravity G of the vibration isolation table 1 as an intersection of diagonal lines.
Support means 2a, 2b, 2c, 2d and 3 having the same spring constant and viscous damping coefficient in the same direction.
By arranging a, 3b, 3c, and 3d, mutual interference of each motion mode in the horizontal plane of the vibration isolation table itself is eliminated, and design and adjustment of control parameters are facilitated. This will be described in detail using the following equation of motion.

The general equation of motion in the horizontal plane of the vibration isolation table with three degrees of freedom is as shown in equation (1).

[0021]

(Equation 1) (1) In the equation, m is the mass of the anti-vibration table 1, I _z is a vertical axis of inertia passing through the center of gravity position G of the anti-vibration table 1, c _xi supporting means 2a, 2b, 2c, 2d of the viscous damping Coefficient, c _yi
Is the viscous damping coefficient of the support means 3a, 3b, 3c, 3d, k
_xi is the spring constant of the support means 2a, 2b, 2c, 2d, k _yi
The spring constant of the support means 3a, 3b, 3c, 3d, the x _i position x-coordinate of the supporting means, the y _i represent respectively the position y coordinates of said support means. X ₀ , y ₀ , θ
_z0 represents the absolute displacement of each mode of translation x, y and rotation θ _z of the installed floor vibration, and F _x , F _y , and M _z represent the translational force and rotation θ of the translation x and y modes acting on the vibration isolation table 1. Represents the moment of _z mode.

In general, as shown in equation (1), the translation and rotation motion modes interfere with each other. For example, even when a pure translational force acts on the vibration isolation table, the effect also affects the rotation mode. Will be transmitted. However, according to the configuration of the present invention, since the positions of the respective support means are symmetrical with respect to the position G of the center of gravity of the vibration isolation table 1, and the spring constant and the viscous damping coefficient of each support means are all equal in the same direction, the vibration isolation is performed. _Off -diagonal components c _ij , k _ij (i ≠
j) are all 0, and there is no interference between the respective motion modes as in the transfer function representing the compliance characteristics and the vibration transmissibility of the vibration isolation table shown in the equations (2) and (3).

[0023]

(Equation 2)

[0024]

(Equation 3) Therefore, the information for each motion mode of the anti-vibration table 1 extracted by using the vibration sensors 6a, 6b, 6c and the motion mode extracting / calculating device 7 is transmitted to the non-interference control calculating devices 8a, 8b, 8
c, the control amount is independently calculated for each motion mode, and the obtained operation amount is calculated using the thrust distribution calculating device 9 for each of the actuators 4a, 4b, 4c, 4d and 5a, 5b, 5c, 5
By feeding back to d, characteristics such as compliance characteristics and vibration transmissibility of the entire active vibration isolation device can be made non-interfering for each motion mode. An active anti-vibration device using a voice coil motor exhibiting excellent responsiveness as an actuator and a control method thereof also belong to the scope of the present invention.

FIG. 2 is a block diagram of the active vibration isolator shown in FIG.

The motion of the vibration isolation table 1 is such that the motion modes having three degrees of freedom in the horizontal plane do not interfere with each other. Therefore, by compensating for each motion mode, the characteristics of the entire control system do not interfere. Becomes In FIG. 2, F _sx , F _sy , M
_sz is the translational x and y mode disturbance force and the rotational θ _z mode moment acting directly on the vibration isolation table 1, and G _x ,
G _y ,

[0027]

[Outside 1] Represents the transfer characteristic of each feedback compensation path in the translation x, y mode and rotation θ _z mode.

From the above, according to the present invention, based on the compliance characteristics and the vibration transmissibility of the active vibration isolator,
A control system can be configured using a relatively simple control operation device, and its control parameters can be easily designed and adjusted. In order to extract information of each motion mode of the vibration isolation table 1, the vibration sensor 6
a, 6b, and 6c are arranged at least one in each of two directions parallel to two orthogonal sides of a rectangle or a square in the horizontal plane, and a plurality of vibration sensors for detecting vibration in the same direction are used for the detection. It is necessary not to be aligned on the same straight line in the direction.

FIG. 1 shows a configuration in which four actuators are arranged in each of the x and y directions, but the arrangement and the number of actuators can be arbitrarily set as long as each motion mode can be controlled. That is, at least three actuators are arranged in at least one direction in each of two directions parallel to two orthogonal sides of the rectangle or the square in the horizontal plane. If they are arranged so as not to be aligned on the same straight line in the direction, their arrangement and number can be set arbitrarily.

FIG. 3 is a diagram showing the configuration of another embodiment of the active vibration isolator of the present invention. In the configuration shown in this figure, vibration in a horizontal plane is controlled by using a minimum of three actuators.

The vibration sensors 6a, 6b, 6 as described above
The arrangement of c is not limited to those shown in FIGS. 1 and 3, but may be any arrangement from which information on three motion modes in a horizontal plane can be extracted. That is, three vibration sensors are arranged at least one in each of two directions parallel to two orthogonal sides of a rectangle or a square in the horizontal plane, and among these, a plurality of vibration sensors that detect vibration in the same direction are: The arrangement may be arbitrary as long as they are arranged so as not to be aligned on the same straight line in the detection direction.

Further, if the number of sensors is three, theoretically, each motion mode of a rigid body in a horizontal plane can be extracted.
By increasing the number of sensors, the degree of freedom in control system design can be increased.

Further, the present invention relates to the motion of the vibration isolation table having three degrees of freedom in the horizontal plane. However, the motion mode in the vertical direction may be considered.

[0034]

As described above, the present invention is arranged at the four corners of a rectangle or square in a horizontal plane with the center of gravity G of the vibration isolation table as the intersection of the diagonal lines. Of the two directions parallel to, the vibration isolating table is supported by supporting means having the same spring constant and viscous damping coefficient in the same direction. By performing control calculations independently for each motion mode, the characteristics of the entire active vibration isolation device can be completely decoupling. As a result, the design and adjustment of the control parameters of the control arithmetic unit can be easily performed with good visibility.
That is, it is possible to design and adjust the control parameters by focusing on each motion mode without considering the influence of the other motion modes. Therefore, the time required for designing and adjusting the control parameters can be significantly reduced as compared with the conventional control method.

Further, since there is no interference of vibrations between the motion modes of the vibration isolation table itself, there is no undesirable characteristic in vibration control, for example, when a translational force acts on the vibration isolation table, rotational vibration is generated. Even when a relatively simple control arithmetic unit is used, it is possible to easily design and adjust the control parameters of the active anti-vibration device, and to easily improve the control performance of the active anti-vibration device. it can.

[Brief description of the drawings]

FIG. 1 is a diagram best illustrating the configuration of an embodiment of an active vibration isolation device of the present invention.

FIG. 2 is a block diagram of the active vibration isolator shown in FIG.

FIG. 3 is a diagram showing a configuration of another embodiment of the active vibration isolation device of the present invention.

[Explanation of symbols]

1 Vibration isolation tables 2a, 2b, 2c, 2d Vibration isolation table support means (x direction) 3a, 3b, 3c, 3d Vibration isolation table support means (y direction) 4a, 4b, 4c, 4d Actuator (x direction) 5a, 5b, 5c, 5d Actuator (y direction) 6a, 6b, 6c Vibration sensor 7 Motion mode extraction operation device 8a, 8b, 8c Non-interference control operation device 9 Thrust distribution operation device

Claims (5)

(57) [Claims] 1. A vibration isolator having a flat plate shape, and disposed at four corners of a rectangle or a square in a horizontal plane having a center of gravity of the vibration isolator as an intersection of diagonal lines, and at two orthogonal sides of the rectangle or the square. Of the two parallel directions,
Supporting means having the same spring constant and viscous damping coefficient in the same direction; a plurality of actuators arranged along two directions parallel to two orthogonal sides of a rectangle or a square in the horizontal plane; A plurality of vibration sensors for detecting vibration, a motion mode extraction arithmetic device for extracting information on each translational and rotational motion mode of the vibration isolation table from an output of each vibration sensor, and an output of the motion mode extraction arithmetic device. A non-interference control operation device that independently performs control operation for each motion mode; and a thrust distribution operation device that distributes a thrust to each actuator from an output of the non-interference control operation device. , Active anti-vibration device. 2. The active vibration isolator according to claim 1, wherein said support means comprises an air spring and a viscous damper. 3. In order to extract information on three degrees of freedom motion mode of the anti-vibration table in a horizontal plane including two translational degrees of freedom and one rotation degree of freedom, three vibration sensors are provided with a rectangle or a square in the horizontal plane. Vibration sensors for detecting vibrations in the same direction are arranged at least one in two directions parallel to two orthogonal sides of each other so as not to be aligned on the same straight line in the detection direction. In order to control the motion mode, at least three actuators acting in at least one direction in at least one direction in each of two directions parallel to two orthogonal sides of a rectangle or a square in the horizontal plane have the same direction of action. The active vibration isolator according to claim 1, wherein the active vibration isolators are arranged so as not to be aligned on the same straight line. 4. The active vibration isolator according to claim 1, wherein a voice coil motor is used as the actuator. 5. Extracting each motion mode having three degrees of freedom in a horizontal plane of the vibration isolation table supported by the support means using an arithmetic unit that extracts information of each motion mode from an output of a vibration sensor; By performing control calculations independently for each motion mode using the non-interference control calculation device, and controlling each actuator using a calculation device that distributes thrust to each actuator, the horizontal position of the vibration isolation table is controlled. 3
The motion mode having a degree of freedom is independently controlled, and a control parameter of the control arithmetic unit is designed and adjusted for each motion mode of the vibration isolation table. For controlling an active vibration isolation device.