JP4327520B2 - Active vibration isolator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used in the field of, for example, various types of precision processing equipment and precision measuring equipment including a semiconductor exposure apparatus, and is used to remove vibration of a movable stage that requires quick and accurate positioning. The present invention relates to a vibration isolator.
[0002]
[Prior art]
In order for various precision processing equipment and precision measurement equipment to function properly, including a semiconductor exposure apparatus that performs exposure by mounting a silicon wafer on a movable stage that requires accurate and high-speed movement and positioning, the floor must It is important to remove the disturbance vibration from the linear motion and the direct acting disturbance vibration generated in the movable stage. For this reason, the movable stage is arranged on the vibration isolation table, and the combined use of dampers and the introduction of active control are attempted. However, in recent years, the weight of the moving part including the movable stage and the load has increased and the moving speed has been increased, and the reaction force against the vibration isolation table when accelerating the movable stage has been increasing. The vibration amplitude of the movable stage increases, and the positioning and setting time of the movable stage and the stopping accuracy tend to deteriorate.
[0003]
Conventionally, active control introduced to suppress vibration of the movable stage is a feedback type in which generated vibration is detected by a position sensor, an acceleration sensor, or the like, and the detected vibration is controlled by an actuator. In this case, improvement of the setting time and positioning performance of the movable stage can be expected due to a decrease in the transient response of the vibration isolation table, but there is a problem that there is a feedback control delay and the initial impulse cannot be suppressed.
[0004]
On the other hand, a feedforward type active vibration isolator has been devised that predicts the vibration of the movable stage and controls the actuator to control the vibration of the movable stage. In this feed-forward type active vibration isolator, prediction accuracy and real-time performance are particularly important, but there is no controller that performs feed-forward in real time in consideration of these.
[0005]
Under such circumstances, conventionally, as a device for suppressing vibration of the movable stage, a feedback type or feedforward type active vibration isolator is known (for example, see Patent Documents 1, 2, and 3).
[0006]
[Patent Document 1]
JP 2001-355669 A [Patent Document 2]
JP 2001-140972 A [Patent Document 3]
Japanese Patent No. 3265670
[Problems to be solved by the invention]
In the case of the above-described feedback type active vibration isolator, there is a problem that an initial response remains because the response speed until the generated vibration is suppressed is insufficient and the follow-up performance of the vibration control operation with respect to the generated vibration is poor. Further, in this case, in the operation of the actuator of the vibration isolation table to be controlled, there is a problem such as generation of a tilt due to a response delay of a component that cancels vibration due to movement of the movable stage.
[0008]
On the other hand, although a vibration isolator that performs feedforward control using only an ordinary high-pass filter and primary and secondary low-pass filters has been proposed (Patent Documents 1 and 2), the filter characteristics are too simple and good control is achieved. There is a problem that is not guaranteed.
[0009]
Further, in the case of a feedforward active vibration isolator that operates the vibration isolating means in advance (Patent Document 3), the difference between the state when learning and storing and the state when actually controlling, and the generation timing of the feedforward waveform Good control performance cannot be obtained due to a shift in position. In order to eliminate the deviation between the generation timing of the feedforward waveform and the movement of the stage, in addition to the precise position control of the stage, the precise control of the moving speed is necessary, and the control of the stage becomes complicated. Further, on-site adjustment and confirmation such as learning about the movement of the stage needs to be performed for each production pattern, and there is a problem that it is troublesome in terms of management.
An object of the present invention is to provide an active vibration isolator capable of performing high-performance control for vibration isolation of a movable stage.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a vibration isolation table that supports a movable stage that operates to position a mounted object, and supports the vibration isolation table, and vibration isolation with respect to the vibration isolation table. In the active vibration isolator including an actuator that applies a force for the above and a control system that operates the actuator so that a force that cancels the vibration of the vibration isolation table is applied to the vibration isolation table, the control system includes: The first transfer function relating the operation state of the movable stage and the operation state of the vibration isolation table generated in association therewith, the operation state of the actuator and the operation state of the vibration isolation table generated in association therewith. The operating state of the movable stage obtained from the inverse transfer function obtained from the related second transfer function and the operating state of the actuator for canceling the vibration of the vibration isolation table caused thereby. By using a transfer function that relates, based only on input signals indicating the operating state of the movable stage to be input in real time, and the formed configuration to output a feedforward control signal for operating the actuator .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a movable stage 2 to which an active vibration isolator 1 according to the present invention is applied.
The active vibration isolation device 1 is provided for active vibration isolation with respect to the movable stage 2 and the mounted object O that is an object to be positioned supported on the movable stage 2, and a vibration isolation table 11 that supports the movable stage 2 and an actuator. And a control system 14 including a vibration sensor S ₁ and a displacement sensor S ₂ as detection means in addition to the active control unit 13.
[0012]
On the vibration isolation table 11, a screw rod 21 that is screwed into an internal screw portion (not shown) provided in the movable stage 2, extends horizontally through the movable stage 2, and is rotatably supported, and the screw rod. The motor 22 that rotates the motor 21 and the vibration sensor S ₁ that detects the vibration state of the vibration isolation table 11 are provided. The motor 22 is controlled by a stage control unit 23 in which a target value is set in advance. The motor 22 rotates by the number of rotations indicated by the control signal from here, and a signal indicating the current rotation state of the motor 22, that is, the position of the movable stage 2 Is input from the motor 22 to the stage controller 23.
[0013]
The pneumatic actuator 11 is connected to an air pressure source 25 via an electropneumatic converter 24, receives supply of pressurized air therefrom, and is interposed between a base 26 installed on the floor and the vibration isolation table 11. Thus, the vibration isolation table 11 is supported horizontally.
Incidentally, on the base 26, the displacement sensor S ₂ is provided as described above to detect the displacement state of the anti-vibration table 11.
[0014]
The active control unit 13 of the control system 14 includes a feedforward controller 31, a feedback controller 32, an electropneumatic converter driver 33 and an attitude controller 34. Then, a signal indicating the position of the movable stage 2 is input from the stage controller 23 to the feedforward controller 31, and a signal indicating the vibration state of the vibration isolation table 11 is input from the vibration sensor S ₁ to the feedback controller 32. A signal indicating the displacement state of the vibration isolation table 11 is input from the sensor S ₂ to the attitude controller 34.
[0015]
The feedforward controller 31 sends to the adder 41 a first transfer function that relates the operating state of the movable stage 2 and the operating state of the vibration isolation table 11 that accompanies this, and the operating state of the pneumatic actuator 11 and this. The operating state of the movable stage 2 and the vibration of the anti-vibration table 11 resulting from this are obtained from the inverse transfer function obtained from the second transfer function that correlates with the operating state of the anti-vibration table 11 that accompanies the vibration. A feedforward control signal for operating the pneumatic actuator 11 based on an input signal indicating the operating state of the movable stage 2 inputted in real time using a transfer function relating the operating state of the pneumatic actuator 11 to be canceled. Is entered. Further, this signal is input from the adder 41 to the adder 42 in the opposite direction. Of course, depending on the type of signal indicating the obtained operating state, there may be an addition without inversion.
[0016]
From the feedback controller 32, a control signal for canceling the vibration of the vibration isolation table 11 is input to the adder 42, and from the posture controller 34 to the adder 42 from the normal displacement state of the vibration isolation table 11. A control signal for canceling the deviation is input. Then, a control signal obtained by adding the three control signals input to the adder 42 is input from the adder 42 to the electropneumatic converter driving driver 33, and based on this, is output from the electropneumatic converter driving driver 33. The electropneumatic converter 24 operates based on the drive signal. That is, the electropneumatic converter 24 responds quickly and accurately to the operation of the movable stage 2 and the vibration and displacement of the vibration isolation table 11, and the amount of pressurized air is continuously adjusted in the pneumatic actuator 11, so that the driving stage 2 vibration isolation is performed.
As the electropneumatic converter 24, for example, an electropneumatic servo valve that operates a flapper with a magnet is used.
[0017]
The signal indicating the operating state of the movable stage 2 input to the feedforward controller 31 may be obtained from a displacement sensor attached to the movable stage 2 instead of from the stage controller 23 as described above. It may be obtained from the control signal from the motor 23 to the motor 22, and the method for obtaining it is not limited.
Further, instead of the pneumatic actuator 11, a solid element such as a piezo element or a giant magnetostrictive element or a linear motor may be used.
[0018]
Although the illustrated actuator is shown as a pneumatic actuator that operates up and down, the actuator and sensor that satisfy the conditions of controllability and observability are generally used by considering the vibration isolation table 11 to be controlled as a rigid body. It is done. A minimum of six sensors and six actuators are required to control for all rigid body degrees of freedom, but these are shown in a simplified manner in the figure.
[0019]
【The invention's effect】
As is clear from the above description, according to the present invention, the vibration isolation table that supports the movable stage that operates to position the mounted object, the vibration isolation table, and the vibration isolation table In an active vibration isolator comprising: an actuator that applies a force for vibration isolation and a control system that operates the actuator so that a force that cancels the vibration of the vibration isolation table is applied to the vibration isolation table. A control system relates a first transfer function that relates the operating state of the movable stage and the operating state of the vibration isolation table that accompanies this, and the operating state of the actuator and the operation of the vibration isolation table that accompanies this The actuator for canceling the operating state of the movable stage and the vibration of the vibration isolation table that accompanies the operating state obtained from the inverse transfer function obtained from the second transfer function relating the state A configuration configured to output a feedforward control signal for operating the actuator based on an input signal indicating the operating state of the movable stage input in real time using a transfer function relating the operating state. It is as.
[0020]
Therefore, there is an effect that high-performance control for vibration isolation with respect to the movable stage becomes possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of an active vibration isolator according to the present invention and a movable stage to which the active vibration isolator is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Active vibration isolator 2 Movable stage 11 Vibration isolator 12 Pneumatic actuator 13 Active control part 14 Control system 21 Screw rod 22 Motor 23 Stage control part 24 Pneumatic converter 25 Pneumatic pressure source 26 Base 31 Feedforward controller 32 Feedback Controller 33 Electropneumatic converter driver 34 Attitude controller 41 Adder 42 Adder O Mounted object S ₁ Vibration sensor S ₂ Displacement sensor

Claims (1)

A vibration isolation table that supports a movable stage that operates to position the load;
An actuator that supports the vibration isolation table and applies a force for vibration isolation to the vibration isolation table;
In an active vibration isolator including a control system that operates the actuator so that a force for canceling the vibration of the vibration isolator is applied to the vibration isolator,
The control system is
The first transfer function that relates the operating state of the movable stage and the operating state of the vibration isolation table that accompanies this, and the operating state of the actuator and the operating state of the vibration isolation table that accompanies the first transfer function A transfer function obtained from the inverse transfer function obtained from the second transfer function to be attached, which relates the operating state of the movable stage and the operating state of the actuator that cancels the vibration of the vibration isolation table that accompanies the operating state. An active vibration isolation device configured to output a feedforward control signal for operating the actuator based only on an input signal indicating an operating state of the movable stage input in real time. .

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