JPH03231314A - Positioning device - Google Patents

Abstract

PURPOSE:To attain the highly accurate positioning operation with a large stroke and at high speed by moving a rough or fine adjustment device to a target position in accordance with the difference between the position of an object to be positioned detected by a position sensor and a target position. CONSTITUTION:A main controller 30 produces a command to actuate a friction drive mechanism 3 and also gives a command to a laser controller 27 to actuate a laser oscillator 20. A laser beam is divided into two pieces by a beam splitter 21. On of both divided beams is reflected by a mirror 10 via an optical interferometer 22. This reflected beam produces an interference beam via an interferometer 22, and this interference beam is made incident on a receiver 25. Meanwhile the other laser beam is reflected by a bender 23 and then by a reflecting mirror 13 via an interferometer 24. Then an interference beam is produced by an interferometer 24 and made incident on a receiver 26. An electric signal S1 received from the receiver 25 is inputted to the controller 30. The controller 30 inputs a drive signal CB to the mechanism 3 in accordance with the deviation between the position of the mirror 10 and a target position to drive the mechanism 3. The mechanism 3 moves the mirror 13 to the target position via a rod 5 with the rough adjustment. Then the fine adjustment control is carried out with a signal S2 received from the receiver 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a positioning device that performs positioning by coarse movement, fine movement, etc.

(Prior Art) There are various techniques for positioning an object to be positioned at a target position, among which there is a technique called dual control that uses a coarse movement device and a fine movement device. In this dual control, the object to be positioned is moved toward a target position by a coarse movement device, the coarse movement device is then stopped, and then the object to be positioned is finely moved by a fine movement device to position it at the target position. In this case, the coarse movement device detects the position of the object to be positioned using a position detection sensor and feeds it back to move the object to be positioned, and the fine movement device detects the position of the object to be positioned using the position detection sensor of the coarse movement device. is detected by another position detection sensor and fed back to move the object to be positioned.

(Issue 8 to be solved by the invention) As described above, in dual control, separate position detection sensors must be used for coarse movement and fine movement, which complicates the configuration. ), which limits positioning accuracy. For this reason, higher precision positioning is currently required.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a positioning device that can perform large stroke and high-speed positioning by coarse and fine movements, as well as positioning with higher accuracy than that of a position detection sensor.

[Configuration of the Invention (Means for Solving the Problems) The present invention provides a coarse movement drive mechanism for coarsely moving a positioning object, a fine movement element for finely moving the positioning object, and a position detecting mechanism for detecting the position of the positioning object. selectively and simultaneously actuating the coarse movement drive mechanism and the fine movement element based on the difference between the detection position by the detection sensor and the target position, or at least the fine movement element of the coarse movement drive mechanism and the fine movement element. coarse and fine movement control means for selectively operating the fine movement element, and a voltage corresponding to the displacement applied to the fine movement element in an additive or subtractive manner with respect to the already applied voltage according to the displacement voltage characteristic of the fine movement element to position the object to be positioned at the target position. This is a positioning device that attempts to achieve the above object by being equipped with ultra-fine assisting means.

(Function) By providing such means, the coarse movement control means controls either the coarse movement device or the fine movement device according to the difference between the detected position of the object to be positioned by the position detection sensor and the target position. Both are activated and the object to be positioned moves toward the target position. Then, a voltage corresponding to the displacement according to the displacement voltage characteristic is applied to the fine movement element by the fine movement means in an additive manner to the already applied voltage, and the object to be positioned is positioned at the target position.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a positioning device. A friction drive mechanism 3 for moving the slider 2 is provided on the support base 1 . That is, this friction drive mechanism 3 is equipped with a static pressure bearing 4, and a drive rod 5 is supported by this static pressure bearing 4. The slider 2 is connected to the tip of the drive rod 5 and moves in response to movement of the drive rod 5. The slider 2 is supported by a hydrostatic bearing 6 and guided by a guide body 8 supported at both ends by support stands 7.8.

A reflecting mirror 10 is mounted on the slider 2, and a piezoelectric element 12 is also provided with an auxiliary plate 11 interposed therebetween. Therefore, the reflecting mirror 10 and the piezoelectric element 12 move together with the movement of the slider 2. This piezoelectric element 12 is formed into a cylindrical shape as shown in FIG. 2 when shown in an enlarged view, and is displaced in the X direction by application of a voltage. Further, a reflecting mirror 13 is provided at the tip of this piezoelectric element 12. By the way, in such a device, positioning is performed with respect to the reflecting mirror 13.

Further, a laser oscillator 20 as a laser length measurement system is provided on the support base 1, and a beam splitter 21 is provided in the laser output direction of the laser oscillator 20, and one of the laser branch output directions of the beam splitter 21 is provided. An optical interferometer 22 is placed on one side, and a bender 23 and an optical interferometer 24 are placed on the other side. Receivers 25 and 26 are connected to each of the optical interferometers 22 and 24, respectively, so that each interference light is converted into each electric signal Sl+ 82 and output. In addition, these electric signals Sl+82
is the output of the laser length measurement system.

Further, the output of the laser beam of the laser oscillator 20 is controlled by a laser controller 27.

On the other hand, a main control device 30 is provided, and this main control device 30
Coarse movement, fine movement, and ultra-fine movement are controlled by .

That is, this main controller 30 has the functions of coarse movement control, fine movement control, and extremely fine movement control. Coarse movement control is a function of receiving the electric signal 81 from the receiver 25 to determine the position of the reflecting mirror 10, and sending out a coarse movement drive signal CB according to the deviation between this position and the target position. Note that the coarse movement drive signal CB is sent to the friction drive mechanism 3 through the amplifier 31,
This forms a feedback control system.

The fine movement control is a function of receiving the electric signal S2 from the receiver 26 to determine the position of the slider 2, and sending out a fine movement drive signal CA according to the deviation between this position and the target position. This fine movement drive signal is a voltage signal, and is sent to the ultra-fine movement control circuit 32 through the laser controller 27, and is further applied from the ultra-fine movement control circuit 32 to the piezoelectric element 12 through the amplifier 33, thereby forming a feedback control system. Ru.

The micro-movement control is an oven loop control function that determines a voltage value corresponding to a desired displacement according to the displacement voltage characteristics of the piezoelectric element 12 and sends this voltage value CE to the micro-movement control circuit 32 through the board 34.

The micro-movement control circuit 32 sends the micro-movement drive signal CA to the piezoelectric element 12, latches the voltage value of the micro-movement drive signal CA, and latches the voltage value CE when the micro-movement voltage CE is sent. It has a function of adding and subtracting the voltage value of the fine movement drive signal CA and sending the result to the piezoelectric element 12. Specifically, as shown in Figure 3, an A/D (analog/digital) converts the fine movement drive signal CA into digital.
A conversion circuit 35, a latch circuit 36 that latches the digital micro-movement drive signal from the A/D conversion circuit 35, and an addition/subtraction circuit that adds and subtracts the output of the latch circuit 36 and the micro-movement digital voltage value sent from the board 34. 37, D/ which converts the addition/subtraction output of this addition/subtraction circuit 37 into analog.
It is composed of an A conversion circuit 38 and an electromagnetic switch 39 that switches between the fine movement drive signal CA and the conversion output of the D/A conversion circuit 38. Note that this electromagnetic switch 39 is switched by a command from the main controller 30.

Next, the operation of the apparatus configured as described above will be explained.

First, to perform coarse motion control, the main controller 30 issues an operation command to the friction drive mechanism 3 to enable the friction drive mechanism 3 to operate, and also issues an operation command to the laser controller 27 to operate the laser oscillator 20. let Thereby, the laser oscillator 20 outputs laser light. This laser beam is split into two directions by a beam splitter 21, and one of the laser beams passes through an optical interferometer 22 and reaches the reflecting mirror 10. Then, the light is reflected by the reflecting mirror 10 and enters the optical interferometer 22 again. In this optical interferometer 22, interference light between the laser light from the laser oscillator 20 and the reflected laser light from the reflecting mirror 10 is generated, and this interference light is sent to the receiver 25 and converted into an electric signal S, which corresponds to the light intensity. converted. The other laser beam split by the beam splitter 21 is reflected by the bender 23 and sent to the reflecting mirror 13 through the optical interferometer 24. Then, the light is reflected by the reflecting mirror 13 and enters the optical interferometer 24 again. In this optical interferometer 24, interference light is generated between the laser light from the laser oscillator 20 and the reflected laser light from the reflection mirror 13, and this interference light is sent to the receiver 26 and converted into an electric signal S2 according to the light intensity. be done. Note that the electrical signal S2 is used during the fine movement operation, and therefore is ignored during the coarse movement operation. The electrical signal S8 is sent to the main controller 30, which receives the electrical signal s1, determines the position of the reflecting mirror 10, and generates a coarse drive signal CB according to the deviation between this position and the target position. Amplifier 3
1 to the friction drive mechanism 3. This friction drive mechanism 3
moves the drive rod 5 in response to the coarse movement drive signal CB. When the driving rod 5 moves, the slider 2 moves in response, and the reflecting mirror 13 moves toward the target position. When the reflecting mirror 13 approaches the target position due to this coarse movement, the main controller 30 stops the coarse movement control and executes fine movement control.

In fine movement control, the main controller 30 switches the electromagnetic switch 39 to the a terminal side, receives the electrical signal s2, determines the position of the reflecting mirror 13, and generates a fine movement drive signal CA according to the deviation between this position and the target position. Send out. This fine movement drive signal CA is sent to the very fine movement control circuit 32 through the laser controller 27, and further this fine movement control circuit 3
2 is applied to the piezoelectric element 12 through an amplifier 33.

Thereby, the piezoelectric element 12 is displaced according to the applied voltage value, and the reflection mirror 13 is positioned with respect to the target position with an accuracy according to the measurement accuracy of the laser length measurement system.

Note that in the above operation, the coarse movement control is followed by the fine movement control, but the reflecting mirror 13 may be positioned by performing the coarse movement control and the fine movement control alternately. In this case, the main controller 30
First, the fine movement drive signal CA is applied to the very fine movement control circuit 32. Then, as shown in FIG. 4, a voltage that increases stepwise is applied to the piezoelectric element 12. As a result, the piezoelectric element 12 moves as shown by the arrow a1 in states A and B in FIG.
displacement in the direction. Then, when the piezoelectric element 12 reaches the maximum displacement F shown in state C, the main controller 30 moves the piezoelectric element 12
At the same time, the coarse movement drive signal CB is applied to the friction drive mechanism 3. As a result, as shown in state D, the piezoelectric element 12 is displaced in the direction of arrow a2 and retracted to a position where the displacement is zero, and the friction drive mechanism 3 moves the drive rod 5 by a displacement F in the direction of arrow a1. As a result, the reflecting mirror 10 moves by a displacement F as shown in state D. Next, the piezoelectric element 1 is activated by the fine movement drive signal CA applied again from the main controller 30 to the control circuit 32 for fine movement.
A stepwise increasing voltage is applied to the piezoelectric element 1.
2 is displaced in the direction of arrow a1 as shown in E state. Then, when the piezoelectric element 12 reaches the maximum displacement F, the main controller 30 again reduces the applied voltage to the piezoelectric element 12 to zero and applies the coarse movement drive signal CB to the friction drive mechanism 3, as shown in the F state. The drive rod 5 is moved by a displacement F. As a result, as shown in FIG. 4 and state F, the reflecting mirror 10
moves by a displacement of 2F. Thereafter, by repeating coarse movement and fine movement alternately in the same manner, the reflecting mirror 10 is positioned with respect to the target position with an accuracy corresponding to the resolution of the laser length measurement system.

Note that the voltage applied to the piezoelectric element 12 is increased in steps as shown in FIG. 4, and is made zero when the maximum displacement F is reached, and then the voltage applied to the piezoelectric element 12 is increased in steps as shown in FIG. However, if the voltage applied to the piezoelectric element 12 is simply lowered and then increased stepwise at this time, the reflecting mirror 13 vibrates as shown by the dotted line in FIG. Therefore, as shown in the figure, the voltage applied to the piezoelectric element 12 is lowered to a voltage value of zero or less and then increased stepwise again, and the voltage applied to the friction drive mechanism 3 is The coarse movement drive signal CB is set to a value equivalent to the displacement F.

This suppresses vibration of the reflection mirror 13 during displacement.

Next, the main controller 30 executes micro-movement control.

In this case, the main controller 30 switches the electromagnetic switch 39 to the b terminal side. The main controller 30 also stores the voltage value applied to the piezoelectric element 12 during fine movement control. The main controller 30 stores the voltage displacement characteristics of the piezoelectric element 12.

Here, for example, the voltage displacement characteristic of the piezoelectric element 12 is 0.1 (
n■/1v), and the voltage value applied to the piezoelectric element 12 when it is positioned by fine movement control is 100 (V). In this case, the reflection mirror 13 is moved by 0.5 in the X direction.
To move by nm, the main controller 30 sends a digital value of the micro-movement voltage 5 (V) through the board 33 to the micro-movement control circuit 32 . This ultra-fine movement control circuit 32
Now, the voltage value 100 (V
) is latched as a digital value and sent to the adder circuit 37. Therefore, the adder circuit 37 adds the voltage value 100 (V) applied to the piezoelectric element 12 and the ultra-fine voltage 5 (V), and outputs the sum to 105 (V) to the D/A conversion circuit 38. Thus, this added voltage 105 (V) is converted into analog and applied to the piezoelectric element 12 through the amplifier 33. As a result, the piezoelectric element 12 is slightly displaced (0,5
n-), and the reflecting mirror 13 is positioned with respect to the target position with higher accuracy than the measurement accuracy of the laser length measurement system. In order to move the reflecting mirror 13 by θ, 25n■, the main controller 30 only has to send out a digital value of a voltage of 2.5 (V) for minute movement, and further move the reflecting mirror 13 in the negative direction of X. In order to move by 0.5 rv, the main controller 30 only has to send out a digital value of minus 5 (v) of voltage of micro-movement.

In this way, in the above embodiment, one or both of the friction drive mechanism 3 and the piezoelectric element 12 is operated depending on the difference between the detected position of the reflection mirror 13 measured by the laser length measurement system and the target position. Since the reflection mirror 13 is positioned by moving the reflection mirror 13, and a voltage corresponding to the displacement according to the displacement voltage characteristics is applied to the piezoelectric element 12 to position the target position, large strokes and high strokes due to coarse and fine movements can be avoided. In addition to speed positioning, the reflective mirror 13 can be positioned with higher accuracy than a laser length measurement system without being limited by the accuracy of the laser length measurement system.

In micro-movement control, a voltage according to the displacement voltage characteristics is applied to the piezoelectric element 12, so that highly accurate positioning is possible no matter what the displacement amount is.

Note that although the piezoelectric element 12 has a hysteresis peculiar to the element, since the applied voltage range in micro-movement control is extremely narrow, the displacement of the piezoelectric element 12 can be approximated to a straight line within this range. Therefore, positioning accuracy is not reduced. for example,
The positioning accuracy with conventional dual control is 1.25~2,
Although it does not exceed 5n-, this device can perform positioning with high accuracy of less than O.lna.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, a mechanism using a linear motor or a ball screw feed may be used instead of the friction drive mechanism 3, or a linear encoder or a strain gauge may be used instead of the laser measurement system.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide a positioning device that can perform large stroke and high-speed positioning by coarse and fine movements, as well as positioning with higher accuracy than the accuracy of a position detection sensor. .

[Brief explanation of drawings]

1 to 6 are diagrams for explaining one embodiment of the positioning device according to the present invention, in which FIG. 1 is a configuration diagram, FIG. 2 is an enlarged view of a piezoelectric element, and FIG. 3 is a microscopic diagram. 4 is a diagram showing the displacement when coarse movement and fine movement are operated alternately. FIG. 5 is a diagram showing the movement when coarse movement and fine movement are operated alternately. The figure is a diagram for explaining suppression of vibration when coarse movement and fine movement are operated alternately. DESCRIPTION OF SYMBOLS 1... Support stand, 2... Slider, 3... Friction drive mechanism, 5... Drive rod, 9... Guide body, 10.1
3...Reflection mirror 12...Piezoelectric element, 20...
Laser oscillator, 21...beam splitter, 22.2
4... Optical interferometer, 23... Vendor, 25.26...
・Receiver, 27... Laser controller, 30...
- Main control device, 31. 33... Amplifier, 32... Control circuit for ultra-fine movement, 34... Board.

Claims (1)

[Claims] A coarse movement drive mechanism for coarsely moving the positioning object, a fine movement element for finely moving the positioning object, a position detection sensor for detecting the position of the positioning object, and a difference between the position detected by the position detection sensor and the target position. Coarse and fine movement control means for selectively and simultaneously operating the coarse movement drive mechanism and the fine movement element based on the difference, or selectively operating at least the fine movement element among the coarse movement drive mechanism and the fine movement element. and a very fine movement means for positioning the object to be positioned at the target position by applying a voltage corresponding to the displacement to the fine movement element in an additive or subtractive manner with respect to the already applied voltage according to the displacement voltage characteristic of the fine movement element. A positioning device characterized by: