JPH084830A - Vibration isolating base position control method - Google Patents

Abstract

PURPOSE:To provide a vibration isolating base position control method which can control an object to be controlled completely regardless of the mounting accuracy of a vertical directional displacement sensor fixed onto a supporting element or the object to be controlled. CONSTITUTION:Displacement signals S1, S2, S3, S4 actually measured between an object to be controlled and a supporting element while the object to be controlled on a vibration isolating base 1 is in a down condition are stored in a control circuit 6, and a displacement between the predetermined object to be controlled and the supporting element is subtracted from the target value of the floating mount while the object to be controlled is in down condition. The subtraction value is added to an actually measured displacement which is stored in the control circuit 6, and the added figure is stored in the control circuit 6 as a new target value of floating amount. A detecting distance detected by contactless vertical displacement sensors 5a, 5b, 5c, 5d is controlled so as to obtain the new target value of floating amount stored in the control circuit 6 while the object to be controlled is floating. Therefore, pneumatic springs 4a, 4b, 4c, 4d are feedback-controlled through an electropneumatic analog valve 7 based on a control signal S5 from the control circuit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration isolation table position control method, and more particularly to a vibration isolation table position control method for injecting a vertical control force into an object to be controlled for vertical position control.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
Vertical direction of the controlled object 13 such as a surface plate equipped with precision equipment supported by air springs (not shown) provided at positions Z ₁ , Z ₂ , Z ₃ and Z ₄ In the position control, the vertical displacement sensor is mounted on the support body 12 or the controlled object 13 to detect the vertical displacement, and this displacement signal is input to the electro-pneumatic analog valve to open / close the electro-pneumatic analog valve. The air is supplied to the air spring, and the air is exhausted from the air spring. Further, a control circuit using the theory of linear feedback control or linear feedforward control is used to control the electropneumatic analog valve.

In order to mount the vertical displacement sensor for detecting the vertical displacement of the controlled object 13 on the support 12, for example, a state in which the vertical control force is not injected into the controlled object, that is, the controlled object 13 is used. Is made to stand still without floating from the support 12. In such a state, the support 12
As shown in FIG. 5 (a), the vertical displacement sensors 15a, 15b, 15c, 1 are provided at the respective positions Z ₁ , Z ₂ , Z ₃ , Z ₄ .
5d is attached. Vertical displacement sensor 15a,
The mounting positions of 15b, 15c, and 15d are controlled by the controlled object 1.
The position where the detection distance can be set to, for example, 3 mm with respect to the bottom surface 13a of 3 is set.

When the controlled object 13 is levitated for vertical control, for example, each of the vertical displacement sensors 15a, 15b, 15c and 15d has a detection distance of 5 mm.
The target value of the flying height is set so that Therefore,
If the target object 11 is displaced in the vertical direction, as shown in FIG. _{6, Z 1, Z 2,} Z 3, Z vertical displacement sensor 15a attached to each position of the _fourth support 12, 15b, 15c,
The electro-pneumatic analog valve 17 is opened and closed via the control circuit 16 based on the displacement signal from 15d to supply air to the opposing air springs 14a, 14b, 14c, 14d, and also the air springs 14a, 14b, 14c, 14d. The position of the vibration isolation table 11 is controlled by exhausting the air from the.

[0005]

Such vertical displacement sensors 15a, 15b, 15c, 15d are mounted strictly using a spacer or the like so that the detection distance is set to a target value, but rely on human intuition. Since it is done by all means, there will be an error in mounting. For example, the controlled object 13
Z ₁ , Z ₂ , Z ₃ of the support 12 when the
Vertical displacement sensor 15 mounted at each position of Z ₄
Z ₁ , of the support 12 so that the current value (POS) which is the detection distance of a, 15b, 15c, 15d becomes 3 mm,
A vertical displacement sensor 15 is provided at each predetermined position of Z ₂ , Z ₃ , and Z _4.
a, 15b, 15c, 15d are attached, the current value (POS) of the vertical displacement sensor 15a is 4 mm, and the current value (P) of the vertical displacement sensors 15b, 15c, 15d (P
OS) is 3 mm. The target value (REF) of the flying height is 5 mm.

In this state, when the control circuit 16 using the theory of linear feedback control or linear feedforward control controls the flying height target value (REF) to 5 mm,
As shown in FIG. 5B, the vertical displacement sensor 15b,
15c and 15d have a current flying height value (POS) of 3 mm, so the difference between the flying height target value (REF) of 5 mm is 2 mm.
However, since the current value (POS) of the flying height of the vertical displacement sensor 15a is 4 mm, the target value (REF) of the flying height is
The difference from 5 mm is 1 mm.

As a result, the control circuit 16 is controlled by the controlled object 1
The positions of Z ₂ , Z ₃ , and Z ₄ of ₃ are set to the air springs 14b and 14
2 mm by the c and 14d, while the position of Z ₁ of the controlled object 13 is 1 mm by the air spring 14a.
I can only raise it. Therefore, although the controlled object 13 such as a surface plate on which the precision equipment is mounted is a solid plane, Z ₁ , Z ₂ , Z ₃ , Z _{4 of the} controlled object 13 are controlled.
Since each position of _{No. 1} does not form a plane, and the position of Z ₁ of the controlled object 13 causes a steady deviation, there is a problem that the controlled object 13 cannot be accurately controlled in the horizontal direction at the time of levitation. It was

In order to solve this problem, the current flying heights of the vertical displacement sensors 15a, 15b, 15c and 15d are set for each position of Z ₁ , Z ₂ , Z ₃ and Z ₄ of the controlled object 13. The target value (REF) of the flying height corresponding to the value (POS) was set and adjusted.

[0009]

An object of the present invention is to solve such a conventional problem, and to reliably control a controlled object regardless of the mounting accuracy of a vertical displacement sensor fixed to a support or a controlled object. It is an object of the present invention to provide a vibration isolation table position control method capable of controlling the vibration isolation table.

[0010]

A method for controlling the position of an anti-vibration table according to the present invention which achieves such an object is a control object which is supported on an installation surface such as a foundation, floor or ground by a vertical actuator. And a vibration isolation table position control method in which a control target object is vertically controlled by a vertical direction actuator based on a displacement signal detected by a vertical direction displacement sensor that detects a displacement between installation surfaces, when the control target object is in a descending state. The measured displacement between the controlled object and the installation surface is stored in the storage means, and the predetermined displacement between the controlled object and the installation surface when the controlled object is in the descending state is subtracted from the target value of the flying height. , The subtracted value is added to the measured displacement stored in the storage means, the added value is stored in the storage means as a new target value of the flying height, and when the controlled object floats,
The detection distance detected by the vertical displacement sensor is controlled to a new target value of the flying height stored in the storage means.

When there are a plurality of vertical actuators and vertical displacement sensors, the storage means can set a new target value of the flying height for each of the vertical displacement sensors.

[0012]

According to this vibration isolation table position control method, the displacement measured between the control target and the installation surface by the vertical displacement sensor is stored in the storage means when the control target is in the descending state. Further, the displacement between the predetermined control target and the installation surface when the control target is in the descending state is subtracted from the target value of the flying height. This subtracted value is added to the actually measured displacement stored in the storage means, and this added value is stored in the storage means as a new target value of the flying height.

Then, when the controlled object levitates, the detection distance detected by the vertical displacement sensor is controlled to the new target value of the flying height stored in the storage means. further,
When there are a plurality of vertical direction actuators and vertical direction displacement sensors, the storage means can set a new target value of the flying height for each of the plurality of vertical direction displacement sensors.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vibration isolation table position control method according to the present invention will be described below with reference to the drawings. FIG. 3 (a),
In (b), the anti-vibration table 1 to which the anti-vibration table position control method according to the present invention is applied has Z ₁ , Z ₂ , Z of the support 2 as an installation surface.
_At each position of ₃ and Z ₄ , a controlled object 3 such as a surface plate having precision equipment supported by air springs 4a, 4b, 4c and 4d which are vertical actuators is provided. Non-contact vertical displacement sensors 5a, 5a that detect vertical displacements and output vertical displacement signals to the controlled object 3.
b, 5c and 5d are attached to the support 2 at respective positions Z ₁ , Z ₂ , Z ₃ and Z ₄ . This non-contact vertical displacement sensor 5
The detection distances a, 5b, 5c, and 5d are the detection distances to the lower surface 3a of the controlled object 3, and the detection distances of the non-contact vertical displacement sensors 5a, 5b, 5c, and 5d are 3 to 5, respectively. In the case of 8 mm, the non-contact vertical direction displacement sensors 5a, 5b, 5c and 5d are used as the support 2 with 3 mm as the detection distance.
It is attached to. The non-contact vertical displacement sensor 5
Examples of a, 5b, 5c, and 5d include eddy current elements,
A differential transformer, LED, laser element, etc. can be adopted.

Here, the controlled object 3 is not only a mass to be oscillated such as a surface plate, but also a semiconductor manufacturing IC such as a stepper (reduction projection type exposure machine) mounted on this, an LSI.
It includes precision equipment such as inspection equipment, electron microscopes, and optical application equipment. As shown in FIG. 1, the control system of the vibration isolation table 1 includes non-contact vertical displacement sensors 5a, 5b, 5c, 5
The control circuit 6 which is a storage means for processing the vertical displacement signals S ₁ , S ₂ , S ₃ and S ₄ from d to generate the control signal S _5.
And an electropneumatic analog valve 7 driven by a control signal S ₅ from the control circuit 6. The electropneumatic analog valve 7 supplies air to the air springs 4a, 4b, 4c, 4d based on the control signal S ₅ from the control circuit 6, and the air springs 4a, 4b,
Air is exhausted from 4c and 4d. Air compressed from an air pressure source such as a compressor (not shown) is applied to the electro-pneumatic analog valve 7. Therefore, the air springs 4a, 4b, 4c, and 4d are compressed air from the electropneumatic analog valve 7 and apply the vertical displacement control forces F ₁ , F ₂ , F ₃ , and F ₄ to the controlled object 3. ..

As shown in FIG. 2, the operation of the control circuit 6 for controlling the electro-pneumatic analog valve 7 is as follows. When the control circuit 6 is driven in a stationary state of the controlled object 3, first, Z _{1 of the} support body 2 is moved. , Z ₂ , Z ₃ and Z ₄ at step 10
It is confirmed whether or not the routines 2 to 104 have been executed (step 101). If both be running, the control circuit 6 stores the read d1 initially present value is the detection distance of the non-contact vertical displacement sensor 5a attached to the position of the Z ₁ of the support 2 (step 102) .

Next, a predetermined displacement (sensor mounting ideal amount) d ₀ between the controlled object 3 and the support 2 is subtracted from the target value r of the flying height, and this subtracted value is taken as the actual flying height d ₂ . (Step 103). d ₂ = r−d ₀ Then, a value obtained by adding the current value d ₁ and the actual flying height d ₂ is set as a new flying height target value r ′ (step 104).

R '= d ₁ + d ₂ The above routines of steps 102 to 104 are executed at the Z ₁ position of the support 2 as well as at the Z ₂ , Z ₃ and Z ₄ positions of the support 2. Z ₁ , Z ₂ , Z _{3 of} the support 2,
When the routine of steps 102 to 104 is executed at each position of Z ₄ , the non-contact vertical displacement sensor 5
Feedback control is performed until the current values d _{1 of} a, 5b, 5c, and 5d reach the target values r ′ of the flying heights (steps 105 and 106). A microcomputer is used as the control circuit 6 as described above.

A method for controlling the position of the vibration isolation table 1 thus constructed will be described. The non-contact vertical displacement sensors 5a, 5b, 5c, and 5d are set to Z ₁ , Z ₂ of the support body 2 with reference to the descending position of the controlled object 3 of the vibration isolation table 1 (descent reference point).
Mount at each position of Z ₃ and Z ₄ . The attachment positions of the non-contact vertical direction displacement sensors 5a, 5b, 5c, 5d are, for example, the non-contact vertical direction displacement sensor 5 with respect to the lower surface 3a of the controlled object 3.
The minimum detectable distance 3 mm in the detectable range 3 to 8 mm of a, 5b, 5c, and 5d is set as the position where the current value d ₁ can be set. The mounting position is the non-contact vertical displacement sensor 5
The non-contact vertical displacement sensor 5 is obtained from the value obtained by subtracting the actual flying height from the maximum detection distance 8 mm of a, 5b, 5c, and 5d.
Any current value d ₁ may be used as long as it is within the minimum detection distance of 3 mm of a, 5b, 5c, and 5d.

Here, the non-contact vertical displacement sensor 5a,
The current value detected by 5b, 5c, 5d is d ₁ = 3
I intend to attach it to the support 2 so that it becomes mm,
It is assumed that only the current value detected by the non-contact vertical displacement sensor 5a is d ₁ = 3.1 mm. At such a vertical descent reference point of the controlled object 3 (d ₁ = 3.1 mm for the non-contact vertical displacement sensor 5 a and d ₁ = 3 mm for the non-contact vertical displacement sensors 5 b, 5 c, 5 d), The control circuit 6 is driven to start the control. At this time, since the controlled object 3 is in the lowered state, the control circuit 6 reads the vertical displacement signal S ₁ of the current value input from the non-contact vertical displacement sensor 5a and d ₁ = 3.
Remember 1 mm.

Next, the predetermined displacement d ₀ = 3 mm between the controlled object 3 and the support 2 is set to the target value of the flying height r = 5 mm.
Subtract from. d ₂ = r−d ₀ = 5-3 = 2 mm, and the current value d ₁ = 3.1 mm and the actual flying height d ₂ =
A value obtained by adding 2 mm is set as a new target value r ′ of the flying height.

R ′ = d ₁ + d ₂ = 3.1 + 2 = 5.1 mm Further, the above routine is performed by the non-contact vertical displacement sensor 5
The steps b, 5c, and 5d are also sequentially executed. In the case of the non-contact vertical displacement sensors 5b, 5c and 5d, d ₁ =
Since it is 3 mm, d ₂ = r−d ₀ = 5-3 = 2 mm r ′ = d ₁ + d ₂ = 3 + 2 = 5 mm.

The target value r'of each new flying height is input to the electropneumatic analog valve 7 as a control signal S ₅ , and the electropneumatic analog valve 7 receives the non-contact vertical displacement sensor based on the control signal S _5. Air spring 4 corresponding to 5b, 5c, 5d
Supply air to a, 4b, 4c, and 4d, and air springs 4a and 4
The vibration isolation table 1 is feedback-controlled by exhausting air from b, 4c, and 4d.

As a result, the non-contact vertical displacement sensor 5
a, 5b, 5c, when the current value detected by the 5d are different, the air springs 4a, 4b, 4c, Z ₁ of the controlled object 3 by 4d, Z _2, Z _3, each position of the Z ₄ Since the flying height of the control object 3 can be made the same,
The levelness of the controlled object 3 can be maintained without changing the target value of the flying height for each position of ₁ , Z ₂ , Z ₃ , and Z ₄ .

In the above embodiments, the vertical displacement sensor is attached to the support. However, the present invention is not limited to this, and even if the vertical displacement sensor is attached to the controlled object, the same effect as this embodiment is obtained. Can be obtained.

[0026]

As is clear from the above description, according to the vibration isolation table position control method of the present invention, the control target supported by the vertical actuator on the installation surface such as the foundation, floor or ground. In a vibration isolation table position control method in which a control target object is controlled in the vertical direction by a vertical actuator based on a displacement signal detected by a vertical displacement sensor that detects a displacement between an object and an installation surface, the control target object is in a descending state. The measured displacement between the controlled object and the installation surface is stored in the storage means, and the predetermined displacement between the controlled object and the installation surface when the controlled object is in the lowered state is subtracted from the target value of the flying height. Then, the subtracted value is added to the actually measured displacement stored in the storage means, the added value is stored in the storage means as a new target value of the flying height, and when the controlled object floats,
By controlling the detection distance detected by the vertical displacement sensor to the new target value of the flying height stored in the storage means, each vertical displacement sensor can be mounted without strict adjustment using a spacer or the like. In addition, the levelness of the controlled object during floating is guaranteed.

As a result, the labor for adjusting the vibration isolation table can be greatly saved, and the quality of the control system can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a vibration isolation table to which a vibration isolation table position control method of the present invention is applied.

FIG. 2 is a flowchart of a vibration isolation table position control method according to the present invention.

3A and 3B are diagrams of a vibration isolation table to which a vibration isolation table position control method of the present invention is applied, in which FIG. 3A is an upper sectional view and FIG. 3B is a side view.

FIG. 4 is a perspective view of a conventional vibration isolation table.

5A and 5B are views showing a mounting state of a vertical displacement sensor of a conventional vibration isolation table, in which FIG. 5A is a diagram showing a current value, and FIG. .

FIG. 6 is a block diagram of a conventional vibration isolation table.

[Explanation of symbols]

1 ... Vibration isolation table 2 ... Support body (installation surface) 3 ... Control object 4a, 4b, 4c, 4d ... Non-contact vertical direction displacement sensor 5a, 5b, 5c, 5d ... Air spring (vertical direction actuator) 6 ... Control Circuit (memory means) 7 ... Electro-pneumatic analog valve d ₀ ... Ideal amount of sensor attachment (predetermined displacement between control object and support) d ₁ ... Current value (displacement actually measured) d ₂ ... Actual flying height (Subtracted value) r ... Target value of flying height r '... Target value of new flying height

Claims (2)

[Claims] 1. A vertical actuator based on a displacement signal detected by a vertical displacement sensor that detects a displacement between a control target object supported on an installation surface such as a foundation, floor or ground by a vertical actuator and the installation surface. In a vibration isolation table position control method for controlling the control target object in the vertical direction by the vertical direction actuator, the measured displacement between the control target object and the installation surface when the control target object is in a descending state is stored in a storage unit. When the control object is stored, the predetermined displacement between the control object and the installation surface when the control object is in a lowered state is subtracted from the target value of the flying height, and the subtracted value is stored in the storage means. Add to the measured displacement,
The addition value is stored in the storage unit as a new target value of the flying height, and when the control target is floated, the detection distance detected by the vertical displacement sensor is stored in the storage unit. A method for controlling the position of an anti-vibration table, which comprises controlling the flying height to a target value. 2. The storage means, when there are a plurality of the vertical actuators and the vertical displacement sensors, sets a new target value of the flying height for each of the plurality of vertical displacement sensors. The vibration isolation table position control method according to claim 1.