KR102524277B1 - Active damping device - Google Patents

Abstract

An active damping device (A) suppresses the vibration of a stage (4) for determining the position of a mounted object (S), a vibration isolation table (1) supporting the stage (4), and the vibration isolation table (1). a servo valve 24 that provides a control force for controlling the movement of the stage 4; a stage information acquisition unit 6d that acquires in advance a stage state signal based on information related to movement control of the stage 4; and a resonant frequency component from the stage state signal The servo valve ( 24) is provided with a damping FF controller 6e that feed-forward controls.

Description

Active damping device

The technology disclosed herein relates to an active damping device.

[0003] Conventionally, in manufacturing apparatuses for various precision instruments such as semiconductors and liquid crystal panels, it is widely known to mount an object to be manufactured on a movable stage in order to realize accurate and high-speed positioning (see Patent Document 1, for example).

In general, the payload on the stage is a precision instrument during manufacturing, so vibration is avoided. Therefore, Patent Document 1 discloses using an active damping device in order to suppress transmission of vibration from the floor as much as possible.

Specifically, in Patent Document 1, a movable stage (moving object), a vibration isolation table (tablen) supporting the stage, and an actuator (servo valve) that imparts a control force to the vibration isolation table to suppress vibration of the vibration isolation table and an active vibration isolation device having a vibration sensor (acceleration sensor) installed on a vibration isolation table. This active damping device is configured to feedback-control the actuator based on a signal from the vibration sensor.

It is also known that in addition to the feedback control described above, feed forward control is also performed on the vibration isolation table in order to suppress not only the vibration transmitted from the floor but also the vibration generated along with the movement of the stage.

Specifically, in the active damping device disclosed in Patent Document 1, when performing stage movement control, the stage position and acceleration are estimated in advance based on information related to the movement control (stage control information). Then, this active damping device performs feed-forward control based on the pre-estimation result. In this way, it is possible to perform feedforward control of the vibration isolation table at a quick timing.

Japanese Patent Publication No. 4970904

However, as described in Patent Literature 1, when a movable stage is supported by a vibration isolation table, there is a possibility that vibration between the vibration isolation table and the stage, vibration between the stage and a mounted object, or the like may lead to resonance. Such resonance is required to be suppressed in advance before it actually occurs.

Further, in general, in a movable stage as described in Patent Document 1, in order to suppress vibration generated in the stage, feedforward control is performed for the stage itself (so-called stage), apart from feedforward control for the vibration isolation table. FF control) is also known.

Therefore, in the control loop constituting the stage FF control, a digital filter such as a notch filter is provided to remove a frequency component that causes resonance related to the stage (in this specification, such a frequency component is referred to as a "resonant frequency component"). You can think of intervening. In this case, it is considered that the occurrence of resonance can be suppressed beforehand by, for example, removing the resonance frequency component from the feed forward signal related to the stage.

However, in general, a phase delay occurs in a digital signal transmitted through a digital filter. Since this causes a time delay in stage FF control, it is unsuitable for securing the responsiveness of the stage and the like.

In addition, there is a possibility that the gain of the digital signal becomes insufficient by the amount by which the resonant frequency component is removed simply by passing through the notch filter. This is unsuitable from the viewpoint of stage movement control performance (in particular, securing of thrust and acceleration applied to the stage), such as the stage FF control described above. On the other hand, adding signal processing for supplementing the digital signal gain, for example, is undesirable because phase delay becomes even more remarkable.

The technology disclosed herein was made in view of these points, and its object is to suppress the occurrence of stage-related resonance without causing time delay in an active damping device provided with a movable stage. there is.

As a result of repeated intensive studies, the present inventors have found that the stage-side control loop and the damping table-side control loop are mutually independent, and, as described in Patent Literature 1 above, control is performed at a faster timing than stage movement control. I paid attention to the fact that it was controllable, and came to discover this indication.

Specifically, the technology disclosed herein relates to an active damping device. This active damping device includes a stage for determining the position of a mounted object by receiving thrust and moving, a first actuator for applying thrust to the stage, and a thrust according to the control signal by inputting a control signal to the first actuator. A first control unit that generates a vibration isolation table supporting the stage, a second actuator that applies a control force to suppress the vibration of the vibration isolation table, and the first control unit via the first actuator When the stage is moved, a stage information acquisition unit that acquires in advance a stage state signal based on the movement control-related information, and the stage state signal acquired by the stage information acquisition unit is input, and from the stage state signal , a resonance suppression unit configured to remove a resonance frequency component of resonance with respect to the stage, and the vibration isolation table is moved along with the movement of the stage based on a stage state signal from which the resonance frequency component has been removed by the resonance suppression unit. and a second control unit that feed-forward controls the second actuator so that a control force corresponding to the generated vibration is provided.

Here, the stage state signal may be a signal representing a physical quantity directly related to the resonance of the stage, such as acceleration or thrust applied to the stage, or indirectly related to the resonance of the stage, such as the position of the stage where such acceleration or thrust can be calculated. It may be used as a signal representing a related physical quantity.

Further, "resonance related to the stage" may be, for example, resonance that occurs with stage movement, or may be resonance that occurs as a result of transmission of a control force applied to the vibration isolation table from the second actuator to the stage. . The term "resonance related to the stage" is used in the same sense.

According to the above configuration, the stage information acquisition unit acquires the stage state signal in advance. The resonance suppression unit removes the resonance frequency component from the stage state signal obtained in advance, and then outputs it to the second control unit. The second controller performs feedforward control of the second actuator by using the thus inputted signal.

As a result, even if a phase delay occurs in the stage state signal as a result of removing the resonant frequency component from the stage state signal, the resulting temporal delay is attenuated by obtaining the stage state signal at an advance timing. Thereby, generation of resonance related to the stage can be suppressed without causing a time delay.

As described above, since the stage-side control loop and the damping table-side control loop are independent of each other, even if the resonance frequency component is removed in the damping table-side control loop, no phase delay occurs on the stage side. This is effective in securing the performance of the movement control performed with respect to the stage.

Further, according to the above configuration, even if signal processing for supplementing the gain of this signal is added to the stage state signal from which the resonant frequency component has been removed, the temporal delay caused by it is attenuated due to the same circumstances as above, It becomes possible to carry out the feed forward control of the vibration isolation table at an early stage. As a result, it is advantageous not only for controlling the movement of the stage but also for ensuring the performance of the feedforward control performed with respect to the vibration isolation table.

In addition, the stage information acquisition unit preliminarily estimates an acceleration command value representing the acceleration applied to the stage as the stage state signal, and the resonance suppression unit removes the resonance frequency component from the acceleration command value. may be configured.

According to the above configuration, resonance related to the stage (resonance with respect to the stage) can be prevented from being induced by removing the resonance frequency component from the acceleration command value.

In addition, the stage information acquisition unit preliminarily estimates a thrust command value representing thrust applied to the stage as the stage state signal, and the resonance suppression unit removes the resonance frequency component from the thrust command value. may be configured.

According to the above configuration, by removing the resonance frequency component from the thrust command value, it is possible to prevent the resonance related to the stage from being induced.

Further, the resonance suppression unit may increase the gain of the stage state signal before and after removing the resonance frequency component.

According to this configuration, the gain of the stage state signal is compensated for after or before the resonance frequency component is removed. This becomes advantageous in ensuring the performance of feedforward control in the vibration isolation table.

In addition, other technologies disclosed herein relate to active damping devices. This active damping device includes a stage for determining the position of a mounted object by receiving thrust and moving, a first actuator for applying thrust to the stage, and a thrust according to the control signal by inputting a control signal to the first actuator. A first control unit that generates a vibration isolation table supporting the stage, a second actuator that applies a control force to suppress the vibration of the vibration isolation table, and the first control unit via the first actuator When a stage is moved, a stage information acquisition unit that acquires in advance a stage state signal based on information related to the movement control; A second control unit outputting a feed forward signal for feed forward controlling the second actuator so that the control force corresponding to the vibration generated in the vibration isolation table is input, and the feed forward signal output from the second control unit is input. , a resonance suppression unit configured to remove a resonance frequency component of a resonance related to the stage from the feedforward signal and output it to the second actuator.

According to the above configuration, the stage information acquisition unit acquires the stage state signal in advance and outputs it to the second control unit. The second control unit outputs a feed forward signal based on the thus input signal.

As a result, even if a phase delay occurs in the feed-forward signal as a result of removing the resonance frequency component, the temporal delay due to the phase delay is attenuated by the stage information acquiring unit acquiring the stage state signal in advance. . Thereby, generation of resonance related to the stage can be suppressed without causing a time delay.

Further, the resonance suppression unit may include a digital filter configured not to transmit the resonance frequency component.

As the digital filter, a general low-pass filter, a band elimination filter, a notch filter, or the like can be used.

Further, the resonance suppression unit may include a notch filter configured to suppress a band including the resonance frequency component.

In general, a notch filter has a narrower rejectable band than a band-reject filter. Therefore, the resonant frequency component can be accurately removed by using the notch filter.

As described above, according to the active damping device, in an active damping device having a movable stage, generation of resonance related to the stage can be suppressed without causing a time delay.

1 is a diagram illustrating a schematic configuration of an active damping device.
Fig. 2 is a block diagram illustrating a configuration of control related to a stage.
3 is a block diagram illustrating a configuration of control related to a vibration isolation table.
4 is a diagram illustrating processing related to resonant frequency component removal.
5 is a diagram showing a comparison between an acceleration command value and a signal obtained by increasing a gain after removing a resonant frequency component from the acceleration command value.
6 is a diagram illustrating a difference between a target value and an actual measurement value of a stage position.
Fig. 7 is a view corresponding to Fig. 3 showing an active damping device according to a second embodiment.
Fig. 8 is a diagram corresponding to Fig. 2 showing a modified example of stage-related control.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on drawing. Here, the following description is an example.

<<First Embodiment>>

First, the first embodiment of the present invention will be described.

－Overall configuration of active damping device－

Fig. 1 is a diagram illustrating a schematic configuration of an active damping device A (hereinafter simply referred to as "damping device") according to the present embodiment. 2 is a block diagram illustrating the configuration of control for the stage 4 of the damping device A, and FIG. 3 exemplifies the configuration of controlling the vibration isolation table 1 of the damping device A. It is a block diagram that

The damping device A is configured to mount a precise device D, which is easily affected by vibration, such as a semiconductor-related manufacturing device, on a vibration damping table 1, for example. Here, the device D (hereinafter also referred to as a “mounting device”) supports various types of mounted objects S, such as silicon wafers, on a movable stage 4, and by appropriately moving the stage 4, It is configured to position the payload S on the stage 4 accurately and at high speed.

In general, since the mounted object S on the stage 4 is a precision instrument during manufacturing, vibration is avoided. Therefore, this damping device A is configured as an active damping device in order to suppress transmission of vibration from the floor as much as possible.

Specifically, the damping apparatus A according to the present embodiment includes a stage 4 for determining the position of a mounted object S by moving under thrust, a vibration damping table 1 supporting the stage 4, The vibration isolation table 1 is provided with a servo valve 24 that provides a control force for suppressing the vibration.

Hereinafter, the structure of each part is explained in detail.

The stage 4 is disposed on the main body 3 of the device D, and in this configuration example, is constituted by a ball screw mechanism as a support movable along a predetermined movement trajectory (in this example, the horizontal direction is indicated). On the upper surface of the stage 4, the above-mentioned mounted object S is supported. Here, the guide mechanism of the stage 4 is not limited to the ball screw mechanism. For example, a so-called linear guide or air pressure guide may be used.

In this configuration example, the above-described ball screw mechanism is screwed into an inner threaded portion (not shown) formed in the stage 4, and a threaded rod (not shown) extending horizontally through the stage 4 and , It is composed of a linear motor 31 (shown only in FIG. 2) driven and connected to this threaded rod. As the linear motor 31 rotates the screw rod, the stage 4 moves along the direction in which the screw rod extends.

In this embodiment, a stage controller 5 described later controls the drive of the linear motor 31 to apply thrust in the horizontal direction to the stage 4, thereby moving the stage 4 in the mounting device D. It is configured to implement the location determination of.

Here, the linear motor 31 is an example of the “first actuator”. In addition, when a linear guide or an air static pressure guide is used instead of a ball screw mechanism, a linear motor 31 may be used instead of a rotary motor.

In order to control the drive of the linear motor 31, the position of the stage 4 on the movement trajectory (corresponding to the displacement of the stage 4 in the mounting device D) and the stage 4 are A stage position sensor S4 and a stage thrust sensor S5 for respectively detecting the thrust actually received are provided. It is configured so that detection signals output from these sensors S4 and S5 are input to the stage controller 5, respectively. Here, the stage controller 5 is an example of a "first controller".

The vibration isolation table 1 is constituted by a so-called table, and is supported elastically from below by a plurality of air spring units 2, 2, ... (usually four, but three or more are sufficient). On top of the vibration isolation table 1, the main body 3 of the device D is placed. This is the same as the vibration isolation table 1 supporting the stage 4 with the body 3 interposed therebetween.

In detail, each of the plurality of air spring units 2, 2, ... is configured by an air spring supporting a load in the vertical direction, as shown, and is disposed on the bottom surface and the top is opened. Case 20 and a piston 22 that is inserted into the upper opening in an airtight state through the diaphragm 21 and partitions an air chamber in the case 20. Since the load is supported using the air spring in this way, the damping device A basically has excellent damping performance, but in addition, in the present embodiment, the internal pressure of the air spring is controlled to It is configured to impart a control force for damping vibration to the Jindae 1.

To this end, each air spring unit 2 is provided with an FB acceleration sensor S1 and a displacement sensor S2 for respectively detecting the acceleration and displacement of the vibration isolation table 1 in the vicinity of the supporting position thereof. In addition, a FF acceleration sensor S3 for detecting acceleration (floor vibration) of the lower part of the case 20 is also attached, and detection signals output from each of these sensors S1 to S3 are input to the controller 6, respectively.

In addition, a pipe for supplying compressed air from an air pressure source (not shown) is connected to each air spring unit 2, and the supply flow rate of compressed air to the air spring is controlled by the servo valve 24 provided in the middle of this pipe. Exhaust flow rate can be adjusted. In addition, the controller 6 controls the servo valve 24 based on the signals input from the sensors S1 to S4 and adjusts the supply flow rate and the exhaust flow rate of the compressed air accordingly, thereby reducing the internal pressure of the air spring. Adjust the By adjusting the internal pressure of the air spring, as will be described later, vibration of the vibration isolation table 1 and the mounting device D can be suppressed. Here, the servo valve 24 is an example of a “second actuator”.

And, in FIG. 1, only the air spring unit 2 on the right side, the control system, the vertical FB acceleration sensor (S1), displacement sensor (S2), FF acceleration sensor (S3), piping, servo valve 24, etc. However, such a control system is attached to each air spring unit (2).

In addition, although not shown, such air spring units 2, 2, ... are installed as actuators for generating horizontal control force around the vibration isolation table 1, or air spring units 2, 2, ... ), horizontal vibration of the mounting device D can also be suppressed by installing a plurality of air springs as horizontal actuators and controlling the internal pressure thereof.

－Controls related to the stage－

Next, control of the stage 4 via the linear motor 31 will be described in detail.

In this configuration example, the stage controller 5 includes a stage position FB control unit 5a, a stage thrust FB control unit 5b, a stage vibration estimation unit 5c, and a stage vibration FF control unit 5d; By inputting a control signal to the linear motor 31, it is configured to generate thrust according to the control signal. The stage controller 5 controls the movement of the stage 4 in this way.

As shown in Fig. 2, the input to the linear motor 31 is mainly the position feedback operation amount calculated by the stage position FB controller 5a based on the signal from the stage position sensor S4, and the stage thrust sensor ( S5), a thrust feedback operation amount calculated by the stage thrust FB control unit 5b, and a thrust feed calculated by the stage vibration FF control unit 5d based on a signal from the stage vibration estimation unit 5c. This is done by adding forward manipulated variables. Here, the stage vibration estimation unit 5c is configured to output a signal generated based on a signal from the stage thrust sensor S5 to the stage vibration FF control unit 5d.

The stage position FB controller 5a determines that the detected position value is a predetermined target value (based on the detected value of the stage position sensor S4, that is, the actual position of the stage 4 on the movement trajectory (actually measured position value)). The linear motor 31 is operated so as to converge to a "position command value"). For example, the feedback gain is multiplied by the differential value and integral value of the measured position value, respectively, and subtracted from the position command value after adding them, so as to be a control input (position feedback manipulation amount) to the linear motor 31. Thereby, feedback control regarding the position of the stage 4 can be performed.

In addition, the stage thrust FB controller 5b determines the actual thrust value based on the detected value of the stage thrust sensor S5, that is, the thrust actually received by the stage 4 during its movement (thrust measurement value). The linear motor 31 is operated so as to converge to the target value of (hereinafter, also referred to as “thrust command value”). For example, the differential and integral values of the measured thrust values are multiplied by a feedback gain, and after adding these values, subtracted from the thrust command value, and used as a control input to the linear motor 31 (thrust feedback operation amount). Thereby, feedback control regarding the thrust applied to the stage 4 can be performed.

Further, the stage vibration estimating unit 5c estimates the vibration generated accompanying the application of thrust to the stage 4 based on the detection value of the stage thrust sensor S5. For example, the stage vibration estimating unit 5c stores a model, map, etc. in which the thrust received by the stage 4 and the vibration generated in the stage 4 are correlated, and corresponding to the above-mentioned measured value of thrust. A signal representing the vibration can be calculated and input to the stage vibration FF controller 5d.

Then, the stage vibration FF controller 5d linearly attenuates the vibration based on the output signal from the stage vibration estimation unit 5c, that is, the size of the vibration generated in the stage 4 accompanying the thrust application. It is to operate the motor 31. For example, it is sufficient to multiply a signal indicating the magnitude of shaking by a feed forward gain, invert the sign, and use it as a control input (thrust feed forward manipulated variable) to the linear motor 31. In this way, feedforward control regarding the thrust applied to the stage 4 can be performed.

Here, instead of the configuration using the stage thrust sensor S5, for example, the current input to the linear motor 31 may be detected and feedback control may be performed on the current. In this way, the thrust may be indirectly controlled through a physical quantity related to the thrust (for example, a physical quantity proportional to the magnitude of the thrust, such as the magnitude of current) without using the stage thrust sensor S5.

In this configuration example, the stage controller 5 inputs to the linear motor 31 an electrical control signal determined according to the position feedback operation amount, the thrust feedback operation amount, and the thrust feedforward operation amount. The linear motor 31 adjusts the magnitude of the thrust applied to the stage 4 according to the strength of the control signal, that is, the strength when the control signal is regarded as a current. That is, as the amplitude of the control signal increases, the torque applied to the threaded rod by the linear motor 31 increases, and accordingly, the thrust received by the stage 4 also increases. At this time, the actual measured value of thrust is detected by the stage thrust sensor S5 and fed back to the stage controller 5.

When the thrust is fed back in this way, the effect of friction on the stage 4 and the like are reflected in the signal indicating the actual thrust, that is, the measured value of the thrust. On the other hand, if the thrust is fed forward, the effect of attenuating the shaking occurring in the stage 4 is reflected in the measured value of the thrust.

Further, the linear motor 31 rotates by the rotation number indicated by the control signal, and the current rotation state, that is, the measured position value is detected by the stage position sensor S4 and fed back to the stage controller 5.

－Control for vibration isolation table－

Next, control of the vibration isolation table 1 via the servo valve 24 will be described in detail. For convenience, only the control of the air spring in the vertical direction is described, but when the air spring is installed in the horizontal direction, the same control is performed.

In this configuration example, the controller 6 includes a damping FB control unit 6a, a damping FB control unit 6b, a damping FF control unit 6c, a stage information acquisition unit 6d, etc. By inputting a control signal, a control force for suppressing the vibration is imparted to the vibration isolation table 1.

As shown in Fig. 3, the input to the servo valve 24 is mainly the damping feedback operation amount calculated by the damping FB controller 6a based on the signal from the FB acceleration sensor S1 and the displacement sensor S2. It consists of a damping feedback operation amount calculated by the damping FB control unit 6b based on the output from and a damping feedforward operation amount calculated by the damping FF control unit 6c based on the signal from the FF acceleration sensor S3.

2 and 3, the stage 4-side control loop constituted by the stage controller 5 and the vibration isolation table 1-side control loop constituted by the controller 6 are mutually independent.

The damping FB controller 6a generates a control force for damping the vibration by means of an air spring based on the detected value of the FB acceleration sensor S1, that is, the vertical acceleration of the damping table 1, for example , the differential value and the integral value of the acceleration detection value are multiplied by a feedback gain, and after adding these values, the sign is inverted to provide a control input (damping control feedback operation amount) to the servo valve 24. Thus, it is possible to perform feedback control (vibration suppression feedback control) that exerts the same effect as applying rigidity to the vibration isolation table 1 or increasing the mass of the vibration isolation table 1 .

In addition, the damping FB control unit 6b controls the internal pressure of the air spring so that the amount of change in the vertical position of the vibration isolation table 1 is reduced based on the detected value of the displacement sensor S2, that is, the amount of change in the vertical position of the vibration isolation table 1. It is to suppress the inclination of the vibration isolation table 1 or the shaking caused by it. For example, after subtracting the detected value of the displacement from the target value (0, zero), the control input to the servo valve 24 (damping control feedback operation amount) may be obtained according to the PID control method. Thereby, feedback control (vibration suppression feedback control) regarding the height of the vibration isolation table 1 can be implemented.

In addition, the damping FF control unit 6c is based on the detection value by the FF acceleration sensor S3, that is, the vibration state of the floor, to generate anti-phase vibration for canceling vibration transmitted from it to the damping object. , For example, a control input (damping control feedforward operation amount) to the servo valve 24 can be obtained using a digital filter. The characteristics of this digital filter are the transfer function H(s) when floor vibration is transmitted to the vibration isolation table 1 via the air spring unit 2, and the compensation transmission constituted by the air spring unit 2. The function K(s) is used and is represented by -H(s)·K(s) ^-1 . Thereby, the feed forward control (damping control feed forward control) regarding the vibration of the floor can be performed.

Then, the servo valve 24 is operated by receiving the control input as described above, and the internal pressure of the air spring unit 2 is controlled, so that an appropriate control force is applied to the vibration isolation table 1 as a vibration removal object. That is, with respect to vibration transmitted from the floor, the vibration suppression FF control unit 6c suppresses transmission of vibration by performing vibration suppression feed forward control, while the vibration suppression FB control unit 6a provides vibration suppression feedback for minute vibration that is nevertheless transmitted. Since it is attenuated by performing control, very high damping performance is obtained.

On the other hand, for the relatively large vibration generated by the operation of the mounting device D, that is, the vibration (shake) generated in the vibration isolation table 1 accompanying the movement of the stage 4, in addition to the vibration suppression feedback control described above, Vibration of the vibration isolation table 1 is attenuated by the vibration suppression FB controller 6b performing vibration suppression feedback control. However, since the feedback control is performed after displacement or vibration actually occurs, the effect is inevitably limited. In particular, in the case where the air spring is used to generate the control force as described above, a sufficient effect cannot be expected because the response delay is large.

Therefore, in this configuration example, in order to suppress the vibration generated along with the movement of the stage 4, the vibration suppression feedback control as described above and the vibration suppression feedforward control are implemented at an early timing.

That is, when the stage controller 5 moves the stage 4 via the linear motor 31, the stage information acquisition unit 6d according to this configuration example provides information on movement control (stage control information). A stage state signal based on is obtained in advance. The controller 6 calculates the manipulated variable (damping control feedforward manipulated variable) in advance by using this stage state signal. The vibration isolation table 1 inputs the control signal calculated in this way to the servo valve 24 at an early timing corresponding to the delayed control time of the air spring. As a result, the servo valve 24 is feed forward controlled at an early timing so as to provide a control force corresponding to the vibration generated in the vibration isolation table 1 accompanying the movement of the stage 4 .

Such a stage state signal is a signal related to the control signal output from the stage controller 5 to the linear motor 31, and is estimated in advance by the stage information acquisition unit 6d. As the stage state signal, an acceleration command value indicating acceleration applied to the stage 4, a position command value indicating a target position of the stage 4, a thrust command value described above, or the like can be used. The stage state signal may be any signal that can be detected, calculated, estimated, or the like based on the specifications of the stage 4 or detection results by various sensors. In the following description, a case where an acceleration command value and a position command value are used together as a stage state signal is exemplified.

However, as in the present disclosure, when the movable stage 4 is supported by the vibration isolation table 1, the vibration between the vibration isolation table 1 and the stage 4 and the vibration between the stage 4 and the mounted object S Vibration, vibration between the threaded rod and the stage 4, and the like may lead to resonance. Such resonance is required to be suppressed in advance before resonance actually occurs.

Here, in the control loop constituting the stage vibration FF controller 5d, it is conceivable to intervene a digital filter such as a notch filter for removing the resonant frequency related to the stage 4. It is thought that this makes it possible to suppress the occurrence of resonance beforehand.

However, in general, a phase delay occurs in a digital signal transmitted through a digital filter. Since this causes a time delay in the feed forward control of the stage 4, it is unsuitable for securing the responsiveness of the stage 4 and the like.

In addition, there is a possibility that the gain of the digital signal becomes insufficient by the amount by which the resonant frequency component is removed simply by passing through the notch filter. Since this causes a decrease in thrust or the like, it is unsuitable from the viewpoint of the performance of the feedforward control of the stage 4. On the other hand, adding signal processing for supplementing the digital signal gain, for example, is undesirable because phase delay becomes even more remarkable.

Therefore, in this configuration example, as a characteristic part of the present invention, the resonant frequency component is removed not only in the control loop on the stage 4 side but also in the control loop on the vibration isolation table 1 side.

That is, the controller 6 is input with the position command value and the acceleration command value as the stage state signal acquired by the stage information acquisition unit 6d, and the movement of the stage 4 is controlled by the acceleration command value among them. Based on the resonance suppression section 6f configured to remove the resonance frequency component of the accompanying resonance and the acceleration command value after the resonance frequency component has been removed by the resonance suppression section 6f, the movement of the stage 4 is controlled. A vibration suppression FF control unit 6e for feedforward control of the servo valve 24 is disposed so as to provide a control force corresponding to the accompanying vibration generated in the vibration suppression table 1 .

Here, the damping FF controller 6e receives a timing signal transmitted from the stage controller 5 when controlling the movement of the stage 4, and obtains a damping feed based on an acceleration command value and a position command value as a stage state signal. A control signal (feed forward signal) corresponding to the forward operation amount is input to the servo valve 24 at a timing earlier than the movement control of the stage 4. This damping FF control part 6e is an example of the "second control part".

Further, the resonance suppression section 6f increases the gain of the stage state signal (specifically, the acceleration command value) before and after removing the resonance frequency component in order to compensate for the lack of gain.

－Process related to the elimination of resonant frequency components-

As described above, the stage information acquisition unit 6d acquires in advance the position command value and the acceleration command value as stage state signals based on the information on the movement control of the stage 4, and the resonance suppression unit 6f output as

In detail, the stage information acquisition unit 6d includes a signal output from the stage controller 5 (e.g., a control signal output to the linear motor 31), a stage position sensor S4, and a stage thrust sensor. A position command value and an acceleration command value are estimated based on the stage control information formed by combining at least one of the detection result in (S5), and output as a stage state signal.

Among the position command value and acceleration command value as the stage state signal, the resonance suppression unit 6f transmits the position command value as it is (specifically, it outputs it without performing digital processing), whereas the acceleration command value For , it is configured to output after removing the resonant frequency component through digital processing.

In detail, the resonance suppression unit 6f includes a digital filter configured so as not to transmit a predetermined resonance frequency component among frequency components constituting the acceleration command value. In this configuration example, a so-called notch filter is configured as such a digital filter.

This notch filter is configured not to transmit a band including a resonant frequency component among acceleration command values, but to transmit a band other than that.

4 is a diagram illustrating processing related to resonant frequency component removal. As shown in Fig. 4(a), when the triangular waveform acceleration command value (see dotted line) including the resonant frequency component is passed through a notch filter, the resonant frequency component is removed as shown in Fig. 4(b). A signal representing a trapezoidal waveform (see solid line) is obtained.

However, as can be seen from (b) of FIG. 4 , the peak of the waveform indicated by the solid line is slightly shifted to the right side of the drawing than the peak of the waveform indicated by the dotted line. This indicates that a phase delay occurs as a result of digital processing by the notch filter. In contrast, the resonance suppression unit 6f slightly shifts the peak position of the signal indicated by the solid line to the left side of the drawing by performing a predetermined digital process (see Fig. 4(c)). This eliminates the phase delay. Although there is concern about the occurrence of time delay when performing such processing, as already explained, since the stage state signal is a signal obtained in advance, this delay can be attenuated by an amount obtained at an early timing.

Further, as can be seen from (b) to (c) of FIG. 4 , the time integral of the solid line is reduced than the time integral of the broken line due to the removal of the resonance frequency component. This indicates that the speed realized corresponding to the acceleration command value (in particular, the speed of the stage 4) decreases. Although details are omitted, if this integral amount is reduced, the control force applied to the vibration isolation table 1 via the servo valve 24 also decreases. This is undesirable in ensuring the performance of the feedforward control performed on the vibration isolation table 1 side.

Therefore, the resonance suppression section 6f increases the peak height of the signal indicated by the solid line, that is, the gain of the signal, by performing predetermined digital processing (see Fig. 4(d)). This becomes advantageous in ensuring the performance of the feedforward control performed with respect to the vibration isolation table 1.

－Calculation method of damping feedforward manipulated variable-

Hereinafter, a method of calculating the damping feedforward manipulated variable will be described in detail.

For convenience of description, considering the case where a constant acceleration a is given to the stage 4 and the stage 4 moves linearly on the x-axis as indicated by the arrow in FIG. 1, first, the reference of the stage 4 The movement distance Δx from the position substantially coincides with the position command value described above. When the stage 4 moves in this way, the position of the center of gravity of the entire damping table 1, which is the object to be damped, changes in the x-axis direction, and the static load distribution to the air spring units 2, 2, ... changes. . In this case, the mass of the stage 4 (to be precise, the sum of the mass of the stage 4 and the mass of the loaded object S) is m, the gravitational acceleration is g, and the y-axis passing through the center of the object is defined as It can be said that rotational force N1 = m g Δx occurs in the clockwise direction (θ direction).

Here, when the internal pressure of the air spring is controlled to generate a rotational force in the opposite direction (-θ) with the same magnitude as the above-mentioned rotational force N1, the air spring units 2, 2, ... accompanying the movement of the stage 4 It is possible to suppress the inclination (displacement) of the vibration isolation table 1, which is an object to be damped, and the accompanying shaking, by controlling the internal pressure of these air springs so as to correspond to the change in the load distribution of . In the example of the drawing, the internal pressure of the air spring on the right side is increased while the internal pressure is decreased on the left side. It is specified geometrically.

In addition, as described above, when a constant acceleration a is applied to the stage 4, the reaction force F = -m a accompanying the movement of the stage 4 moves through the main body 3 of the device 3 to the vibration isolation table 1 will work on Since the line of action of this reaction force F is substantially horizontal and does not pass through the center of gravity of the object to be damped, if the vertical distance between this line of action and the center of gravity in the vertical direction is h, the rotational force N2 = -m a h around the y-axis It happens. The vertical distance h may be measured in advance. Considering that the stage 4 moves in the horizontal direction, the vertical distance h is kept approximately constant.

In order to receive the rotational force N2 generated by the reaction force F, as in the above-mentioned rotational force N1, the internal pressure of the air spring in the vertical direction is controlled to generate a rotational force in the opposite direction with the same magnitude as the rotational force N2. Here, the direction of the rotational force N2 is the opposite direction (-θ) to the rotational force N1, so in general, the control input U to the air spring unit 2 (servo valve 24) and the air spring unit 2 (servo valve ( Considering that there is a relationship expressed by the following equation (1) between Fa and Fa generated by 24)), the manipulated variable U _θ is expressed by the following equation (2).

[Equation 1]

[Equation 2]

Here, in equations (1) to (2), Kv, Tv, and Am represent the gain, time constant, and pressure receiving area of the air spring of the servo valve 24, respectively.

In the case of arranging the air springs in the horizontal direction as well, it is preferable to generate a force in the opposite direction (-x direction) equal in magnitude to the reaction force F received by the stage 4 thereby, and the air springs in the horizontal direction The manipulated variable U _x for , is represented by the following formula (3).

[Equation 3]

Here, the manipulated variables U _θ and U _x are converted into manipulated variables for each air spring by a predetermined conversion equation obtained according to the arrangement of each air spring as described above. The damping FF control unit 6e uses the position command value estimated based on the output of the stage position sensor S4 or the like as the movement distance Δx, and the acceleration command estimated based on the output of the stage thrust sensor S5 or the like as the acceleration a. The manipulated variables U _θ and U _x are calculated by using values obtained by removing the resonant frequency component.

－Operation of active damping device－

And, in this configuration example, the internal pressure control of the pneumatic spring based on the damping feedforward operation amount obtained as described above is configured to be executed at a timing earlier than the movement control of the stage 4 as described above.

That is, when movement control of the stage 4 is performed by the mounting device D, first, a control signal related to the movement control is output from the stage controller 5 and input to the controller 6. Receiving this, the stage information acquisition unit 6d of the controller 6 estimates and calculates the position command value and the acceleration command value as stage state signals at a timing earlier than when the movement control of the stage 4 is actually performed, It is sent to the resonance suppression section 6f. The resonance suppression section 6f does not perform digital processing on the position command value and sends it to the damping FF controller 6e, while performing digital processing including resonance frequency component removal on the acceleration command value, and then damping the damping FF. sent to the controller 6e. Receiving this, the damping FF control unit 6e, as described above, obtains the manipulated variables U _θ and U _x for controlling the internal pressure of the air spring.

Then, when a timing signal is output from the stage controller 5 prior to controlling the movement of the stage 4, the damping FF controller 6e receiving the timing signal outputs the manipulated variables U _θ and U _x obtained as described above to air It is output to the servo valve 24 at a timing earlier than the control of the stage 4 by the time delay in the spring control. When the vibration isolation table 1 is about to shake with the movement of the stage 4 via the mounting device D, appropriate control force is applied to the vibration isolation table 1, and the shaking can be sufficiently suppressed. . And, the slight shaking that nevertheless occurs is attenuated by the feedback control of the acceleration and displacement by the damping FB controller 6a and the damping FB controller 6b. Further, with respect to resonance that may occur due to the control force applied to the vibration isolation table 1, its occurrence is suppressed by the resonance suppression section 6f.

5 is a diagram showing a comparison between an acceleration command value and a signal after a gain is increased by removing a resonant frequency component from the acceleration command value. Specifically, FIG. 5 compares the acceleration command value (dotted line) before digital processing in the resonance suppression unit 6f and the acceleration command value (solid line) after digital processing such as resonance frequency component removal or gain increase. to indicate.

6 is a diagram illustrating the difference (position deviation) between the target value and the measured value of the stage 4 position. Specifically, FIG. 6 shows the shake suppression effect by damping feedforward control when the damping feedforward manipulated variable calculated based on the acceleration command value shown in FIG. 5 is used.

Here, in Fig. 6, the short-dashed line represents the transition of the position deviation when vibration suppression feedforward control is not performed (no horizontal displacement MFF), and the long-dashed line shows the vibration suppression feedforward control, but the resonant frequency component is removed. The transition of the position deviation when the acceleration command value (the acceleration command value indicated by the dotted line in FIG. 5) before the movement is used (with horizontal displacement MFF) is shown, and the solid line is the acceleration after vibration suppression feedforward control is performed and the resonance frequency component is removed. Transition of the position deviation in the case of using the command value (the acceleration command value indicated by the solid line in Fig. 5) (horizontal displacement trajectory_filter) is shown. In addition, the dotted line represents the theoretical value of the speed (Theoretical speed) at the time of moving the stage 4.

As shown in the part R surrounded by an ellipse in FIG. 6 , when vibration suppression feedforward control is performed, position deviations converge quickly compared to when vibration suppression feedforward control is not implemented. However, when the acceleration command value before removing the resonant frequency component is used, periodic fluctuations due to the resonant frequency component remain, as indicated by the long dashed line in FIG. 6 . On the other hand, as indicated by the solid line in FIG. 6 , when the acceleration command value after removing the resonance frequency component is used, this periodic fluctuation is eliminated and converges to 0 at a faster timing than other configurations (that is, the adjustment is relatively fast). ) can be seen.

-conclusion-

As described above, as a result of removing the resonance frequency component from the acceleration command value as the stage state signal, even if a phase delay occurs in this signal, the resulting time delay is caused by the stage information acquisition unit 6d. It is attenuated by acquiring it in advance timing. Thereby, generation of resonance related to the stage 4 can be suppressed without causing a time delay.

2 and 3, since the control loop on the stage 4 side and the control loop on the vibration isolation table 1 side are mutually independent, even if the resonance frequency component is removed from the control loop on the vibration isolation table 1 side. , no phase delay occurs on the stage 4 side. This is effective in ensuring the performance of the movement control performed with respect to the stage 4.

In addition, even if signal processing for supplementing the gain of this signal is added to the acceleration command value from which the resonance frequency component has been removed, the time delay caused by this is attenuated due to the same circumstances as above, and the vibration isolation table 1 It is possible to quickly perform feed-forward control of As a result, it is advantageous not only for the movement control of the stage 4 but also for ensuring the performance of the feedforward control performed with respect to the vibration isolation table 1.

Also, in general, a notch filter has a narrower blocking band than a band-reject filter. Therefore, the resonant frequency component can be accurately removed by using the notch filter.

<<Second Embodiment>>

Next, a second embodiment of the present disclosure will be described. In the following description, the same code|symbol is attached|subjected about the part structured similarly to 1st Embodiment, and the description is abbreviate|omitted suitably.

FIG. 7 is a view corresponding to FIG. 3 showing an active damping device according to a second embodiment. As shown in Fig. 7, the damping FF control unit 6e' according to the second embodiment has a changed relative positional relationship with the resonance suppression unit 6f' compared to the first embodiment, and the resonance suppression unit ( 6f'), so as to directly receive the stage state signal output from the stage information acquisition section 6d.

In detail, the damping FF control unit 6e' according to the second embodiment, based on the stage state signal acquired by the stage information acquiring unit 6d, moves the stage 4 and the vibration isolating table 1 ), a feed forward signal for feed forward control of the servo valve 24 is output so that the control force corresponding to the vibration generated in the servo valve 24 is generated.

Further, the resonance suppression section 6f' according to the second embodiment receives the feedforward signal output from the damping FF control section 6e', and the resonance of the stage 4 is resonated with the feedforward signal. It is configured to output to the servo valve 24 after removing the frequency component.

Thus, even if a phase delay occurs in this signal as a result of removing the resonant frequency component from the feedforward signal, the temporal delay caused by it is attenuated by the stage information acquiring section 6d acquiring the stage state signal in advance. . In this way, it is possible to quickly perform the feedforward control of the vibration isolation table 1. As a result, generation of resonance associated with the stage 4 can be suppressed without causing a time delay.

<<Example of modification of stage-related control>>

In the first embodiment described above, it is configured to estimate the thrust generated on the stage 4 based on the detection result by the stage thrust sensor S5, but it is not limited to this configuration. For example, as shown in FIG. 8, it is good also as a structure using the stage acceleration sensor S6. In this case, the stage vibration estimating unit 5c can estimate the vibration generated in the stage 4 based on at least one of the signals output from the stage thrust sensor S5 and the stage acceleration sensor S6.

Further, the stage vibration estimating unit 5c, the stage thrust sensor S5, and the stage acceleration sensor S6 can be used to identify the resonant frequency component. In this case, by attaching the stage acceleration sensor S6 to each part (ball screw mechanism, stage 4, mounted object S, etc.) disposed on the vibration isolation table 1, more accurate identification can be performed. .

<<Other Embodiments>>

In the above embodiment, the servo valve 24 was illustrated as an actuator for the vibration isolation table 1, but it is not limited to this configuration. For example, a linear motor may be used instead of the servo valve 24.

In the above embodiment, both the stage information acquisition unit 6d and the damping FF control unit 6e are part of the controller 6, but they are not limited to this configuration. At least one of the stage information acquisition unit 6d and the damping FF control unit 6e may be part of the stage controller 5.

In addition, the notch filter included in the resonance suppression section 6f is not limited to one. A plurality of notch filters may be used. In this case, it is possible to have a configuration corresponding to a plurality of resonant frequency components.

In addition, the procedure for removing the resonance frequency component, adjusting the peak position, increasing the gain, and the like is not limited to that shown in FIG. 4 and can be changed as appropriate.

Further, the resonance suppression section 6f may be configured with another digital filter such as a low-pass filter instead of a notch filter. The configuration of the resonance suppressor 6f can be changed as appropriate. For example, the digital filter for increasing the gain may be provided in the stage information acquisition section 6d or in the damping FF control section 6e instead of the resonance suppression section 6f.

A: Active damping device
D ： Mounting device
S ： Payload
1 ： Vibration isolation table
2： Air spring unit
3: The body of the mounting device
4: Stage
5: Stage controller (first control unit)
6：Controller
6d: stage information acquisition unit
6e: Damping FF control unit (second control unit)
6f: resonance suppression unit
24: Servo valve (2nd actuator)
31: Linear motor (first actuator)

Claims (7)

A stage that determines the position of the payload by moving under thrust;
a first actuator that applies thrust to the stage;
A first controller for generating thrust according to the control signal by inputting a control signal to the first actuator;
a vibration isolation table supporting the stage;
a second actuator for imparting a control force to suppress the vibration of the vibration isolation table;
a stage information acquisition unit for acquiring in advance a stage state signal based on information related to movement control when the first control unit moves the stage via the first actuator;
a resonance suppression unit configured to input the stage state signal obtained by the stage information acquisition unit and to remove a resonance frequency component of resonance related to the stage from the stage state signal;
Based on the stage state signal from which the resonance frequency component has been removed by the resonance suppression unit, feed-forward control of the second actuator to provide a control force for suppressing vibration generated in the vibration isolation table along with the movement of the stage. A second control unit is provided;
The resonance suppression unit increases a gain of the stage state signal before and after removing the resonance frequency component;
The first control unit outputs a timing signal prior to controlling the movement of the stage;
The second control unit receives the timing signal and transmits a feed forward signal obtained based on the stage state signal from which the resonance frequency has been removed by the resonance suppression unit to the second control unit at a timing earlier than that of the movement control of the stage. input to the actuator
An active damping device characterized in that. According to claim 1,
The stage information acquisition unit preliminarily estimates an acceleration command value representing an acceleration applied to the stage as the stage state signal, and
The resonance suppression unit is configured to remove the resonance frequency component from the acceleration command value
An active damping device characterized in that. According to claim 1,
The stage information acquisition unit preliminarily estimates a thrust command value representing thrust applied to the stage as the stage state signal, and
The resonance suppression unit is configured to remove the resonance frequency component from the thrust command value
An active damping device characterized in that. According to any one of claims 1 to 3,
The resonance suppression unit includes a digital filter configured not to transmit the resonance frequency component.
An active damping device characterized in that. According to claim 4,
The resonance suppression unit includes a notch filter configured to block a band including the resonance frequency component.
An active damping device characterized in that. delete delete

Images