JPH0724002B2 - Positioning control device - Google Patents

Description

Description: TECHNICAL FIELD The invention of this application relates to a device for controlling a position.

More specifically, the invention of this application is an apparatus for controlling an apparatus for performing a large movement and precise positioning, such as a precision positioning apparatus for a hand of an industrial robot or an adjusting apparatus for an optical system of a laser processing machine. Therefore, the present invention relates to a control device that feeds back the operation amount of the fine movement stage to the control amount of the coarse movement stage when positioning is performed by combining the coarse movement stage and the fine movement stage.

[Prior Art] Conventionally, as a high-precision positioning device, there is known a compound-type positioning device that secures high accuracy by combining a coarse movement stage that can move a large amount but has a low movement precision and a fine movement stage that has a small movement but has a high precision. Has been.

As shown in the block diagram of FIG. 5, the control device for such a composite positioning device is installed on the substrate 101 and
A coarse movement stage 102 which moves above, a fine movement stage 103 which is installed on the coarse movement stage 102 and moves on the coarse movement stage 102, a position detection means 116 which detects the position of the fine movement stage 103, and Selection means 108 for selecting one of the fine movement control means 121 and the coarse movement control means 131 corresponding to the deviation between the detected position signal from the position detection means 116 and the target value for positioning from the target value generation means, The coarse movement stage 10 corresponding to the deviation selected when the deviation is larger than a predetermined set value.
2, a coarse movement control means 121 for generating a movement control signal, and a fine movement control means 131 for generating a movement control signal for the fine movement stage 103 which is selected when the deviation is smaller than a predetermined value and which corresponds to the deviation. Fine movement drive means 1 for moving the fine movement stage 103 in response to a control signal from the fine movement control means 131.
41 and a coarse-movement drive means 151 for moving the coarse-movement stage 103 in response to a control signal from the coarse-movement control means 131.

In the control of this composite type positioning device, first, with the fine movement stage 103 fixed on the coarse movement stage 102, only the coarse movement stage 102 is moved to the vicinity of the target position for coarse positioning. Next, when the fine movement stage 103 reaches a predetermined vicinity of the target value for positioning, the coarse movement stage 102 is fixed, and only the fine movement stage 103 is moved to perform accurate positioning control.

[Problems to be Solved by the Invention] In the conventional control device, first, there is a drawback that the control system becomes complicated because the selection means for conditional branching is indispensable.

Next, since the switching control is carried out by the selecting means, there is a drawback that the quick response of the control is poor.

In addition, due to the property that control has to be switched, there is also a drawback that the target position is not smoothly established when a disturbance occurs and the responsiveness deteriorates.

[Object of the Invention] An object of the invention of the present application is to provide a control device that improves the quickness of positioning control and has a simple structure in order to solve the problems of the positioning control device based on the above-mentioned conventional technology. It is what

[Means for Solving the Problems] In accordance with the above-mentioned object, the configuration of the invention of this application is the substrate 1
A coarse movement stage 2 that moves on the substrate 1 to perform coarse positioning, a fine movement stage 3 that moves on the coarse movement stage 2 to perform fine positioning, and a position detection that detects the position of the fine movement stage 3. Means 16 and a fine movement control means for generating a movement control signal for the fine movement stage 3 in response to a deviation between a detection position signal from the position detection means 16 and a target value for positioning.
21. When the movement control signal value of the fine movement stage 3 is between the upper and lower limit set values, the coarse movement stage movement control signal is not generated, and when it exceeds the upper or lower limit set value, the value exceeds the set value. Coarse movement control means 31 for generating a movement control signal for the corresponding coarse movement stage and fine movement control means 21.
Drive means 41 for moving the fine movement stage in response to the movement control signal from the control means and coarse drive means 51 for moving the coarse movement stage 2 in response to the movement control signal from the coarse movement control means 31. The positioning control device is composed of

[Embodiment] An embodiment of the invention of this application will be described below with reference to FIGS. 1 to 4.

The control of the basic embodiment will be described with reference to FIG.

First, the position of the fine movement stage 3 is detected by the position detecting means 16,
Next, the fine movement control means 21 compares and calculates the detected position signal and the target value from the target value setting means, and converts it into a fine movement movement control signal for controlling the position of the fine movement stage on the coarse movement stage and the like. This fine movement control signal is converted into a fine movement drive signal by the fine movement drive means 41 to drive the fine movement stage 3. At the same time, the control signal for fine movement is sent to the control means 31 for coarse movement. The coarse movement control means 31 compares the fine movement movement control signal with a set value indicating the position of the fine movement stage 3 on the coarse movement stage 2 and converts it into a coarse movement control signal. This coarse movement control signal is converted by the coarse movement drive means 51 into a coarse movement drive signal, and the coarse movement stage 2 is driven.

Next, a specific embodiment will be described with reference to FIG. Second
In the figure, 1 is a substrate on which the coarse movement stage 2 is mounted.
The substrate 1 may be a fixed table or a movable table. A coarse movement stage 2 moves on the substrate 1 for rough positioning. Reference numeral 3 denotes a fine movement stage for moving the coarse movement stage 2 with high accuracy. The fine movement stage is supported by the coarse movement stage 2 via a leaf spring 4, and is movable in the spring direction.

Reference numeral 5 denotes a corner cube installed on the fine movement stage 3, which reflects the laser light emitted from the laser interferometer 6 for detecting the position (or distance) and indicates the position of the fine movement stage 3. Reference numeral 6 is for detecting the position (or distance) of the fine movement stage 3, and receives laser light emitted from the corner cube 5 to receive reflected light,
It is a laser interferometer that detects the position (or distance) by detecting the degree of interference. A laser interferometer counter 7 detects the position (or the distance) by counting the laser interference fringes measured by the laser interferometer 6. For position detection, the corner cube 5, the laser interferometer 6 described here,
In addition to the combination of the laser interferometer counter 7, for example, a glass scale, a magnet scale, or the like may be used.

Reference numeral 8 is a well-known microcomputer for calculating control signals for driving both the coarse / fine movement stages 2 and 3. This microcomputer 8 includes a laser interferometer counter 7
The control signal for fine movement and the control signal for coarse movement are calculated from the position signal from and the target value / set value input in advance.

Reference numeral 9 denotes a solid-state actuator driver that emits a fine-movement drive signal that drives the fine-movement stage 3 in response to a control signal from the microcomputer 8. Reference numeral 10 denotes a servo amplifier which issues a coarse drive signal for driving the coarse stage 2 in response to a control signal from the microcomputer 8.

Reference numeral 11 is a solid-state actuator that moves the fine movement stage 3, and is, for example, a piezoelectric element, a magnetostrictive element, or the like. The moving distance (stroke) of the single piezoelectric element is about several tens of μm.
12 is a servo motor, which is a ball screw as shown.
The coarse movement stage 2 is moved by rotating the nut 13 and moving the nut 14. The coarse movement stage 2 moves on the substrate 1 via the ball screw mechanism of the servo motor 12 fixed to the substrate 1.

Next, details of the control system will be described with reference to FIG. The position signal from the laser interferometer 6 is input to the microcomputer 8 via the laser counter 7 and the following processing is performed.

The position signal measured by the laser interferometer 6 is used as the fine movement control means.
The value is input to 21, and first the subtraction means 22 compares it with the target value generated from the target value generation means to calculate the deviation. Next, the deviation signal is subjected to proportional / integral / derivative processing by the well-known PID control means 23, and the upper and lower limits are restricted by the limiter means 24 to control the fine movement (for example, the fine movement stage 3 on the coarse movement stage 2 Control signal for controlling the relative position).
The fine movement control signal is input to the solid-state actuator driver 9, amplified and converted into a signal, and in the case of a piezoelectric element, converted into a potential to drive the solid-state actuator 11.

The fine movement control signal is branched at the same time to the coarse movement control means 31.
Then, the subtracter 32 performs a comparison operation with the set value E from the set value generating means, and inputs it to the dead zone means 33. The dead zone means
33 is the dead band E _{1 to} E ₂ where the fine control signal is near the set value E.
If the inner and outputs a zero, and outputs a signal corresponding to a value obtained by subtracting E ₁ or E ₂ from the input value if the value exceeds the E ₁ or E _2.

Further, this output signal is amplified by the proportional calculation means 34 and input to the servo amplifier 10 as a coarse movement control signal to drive the servo motor 12. At this time, as shown in the figure, in consideration of the fact that the operation of the servo motor 12 is not stable in the low rotation region including the influence of friction, the dither signal from the dither function generating means 36 is used for coarse movement by the adding means 37. It may be added to the control signal.

An example of the operation of this embodiment will be described with reference to FIGS. 4 (a), (b) and (c). The horizontal axis of the figure represents elapsed time.

(A) is a diagram showing the time change of the target value and the time change of the actual position of the fine movement stage when the target value changes stepwise. (B) is a diagram showing a change over time of the signal value of the fine movement control signal corresponding to the relative position of the fine movement stage 3 on the coarse movement stage 2, for example. FIG. 6C is a diagram showing a change over time in a coarse movement control signal value corresponding to, for example, a moving speed control signal of the coarse movement stage.

For the sake of explanation, it is assumed that the set value E is 50% and the dead zone ranges E ₁ and E ₂ are 40% and 60%, respectively.

At the start of control, first, as shown in FIG. 4 (a), a signal corresponding to the deviation ▽ y between the target value and the actual position of the fine movement stage is commanded. The fine movement control signal follows this command value with some delay as shown in FIG. In this operation example, the initial value of the fine movement control signal value is 50% (center position), but this initial value can be set arbitrarily.

This fine movement control signal value is input to the coarse movement control means 31, but in the initial stage, the coarse movement control signal value remains at zero because of the dead zone. That is, initially, the fine movement stage 3
Only the coarse moving stage 2 is stopped and the coarse moving stage 2 is stopped.

When the control signal value for fine movement increases and reaches the dead zone E ₂ (60%), the signal value for coarse movement rises as shown in FIG. 4C, and the coarse movement stage 3 moves to the target value. To start.

Next, depending on the control variable, as in the example shown in FIG. 4B, the fine movement control signal value saturates at the maximum value of 100%, and the fine movement stage 3 stops at the end on the target value side. In this state, only coarse movement stage 2 continues to move.

By moving the coarse movement stage 2, the fine movement stage 3
When enters the area near the target position, the fine movement control signal value decreases along with the coarse movement control signal, the fine movement stage 3 moves from the end to the center, and the movement speed of the coarse movement stage 2 decreases.

When the control signal for fine movement again reaches the dead zone E ₂ value as shown in FIG. 4 (b), the coarse movement stage 2 is stopped and only the fine movement stage 3 moves as shown in FIG. 4 (c). Continue and stop at the target position.

If the dead zones E ₁ and E ₂ are provided near the set value E in this way, when the fine movement stage 3 reaches E ₁ or E ₂ near the set value E, the coarse movement stage 2 is stopped, Only the fine movement stage 3 will be controlled.

EFFECTS OF THE INVENTION Since the invention of this application is configured as described above,
The following effects are achieved.

First, since the coarse movement stage and the fine movement stage move at the same time while being controlled, the quick response of control is improved. At this time, the coarse movement stage operates so that the fine movement stage is established near the set value, so that the responsiveness of control is improved.

Furthermore, there is also an effect of smoothly establishing the target position when a disturbance occurs.

Further, since there is no selection means for conditional branching, the control system can be simplified.

Further, if the dead zone is provided, the fine movement stage can be controlled in the vicinity of the target position while the coarse movement stage is stopped, so that the target position can be established without causing hunting.

[Brief description of drawings]

1 to 4 are explanatory views of an embodiment of the invention of this application, and FIG. 1 is a circuit diagram of one embodiment of the invention of this application,
FIG. 2 is a circuit diagram of another embodiment, FIG. 3 is a block diagram of another embodiment, and FIG. 4 is a graph showing changes in signal values of the embodiment. FIG. 5 is a circuit diagram of a conventional mode. 1 ... Substrate, 2 ... Coarse movement stage 3 ... Fine movement stage, 16 ... Position detection means 21 ... Fine movement control means, 31 ... Coarse movement control means 41 ... Fine movement drive means, 51 ... Coarse Driving means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-73411 (JP, A) JP-A 61-279914 (JP, A) JP-A 64-57318 (JP, A) Actual development Sho-64- 7317 (JP, U)

Claims (1)

[Claims] 1. A substrate, a coarse movement stage that moves on the substrate for coarse positioning, a fine movement stage that moves on the coarse movement stage for fine positioning, and a position for detecting the position of the fine movement stage. A detection means, a fine movement control means for generating a movement control signal for the fine movement stage corresponding to a deviation between a detected position signal from the position detection means and a target value for positioning; and a movement control signal value for the fine movement stage. A coarse movement stage movement control signal is not generated when it is between the upper and lower limit setting values, and a coarse movement stage movement control signal corresponding to a value exceeding the setting value is generated when the upper limit or lower limit setting value is exceeded. A movement control means, a fine movement drive means for moving the fine movement stage in response to a movement control signal from the fine movement control means, and a coarse movement scan in response to a movement control signal from the coarse movement control means. A coarse driving means for moving the over-di consists positioning control apparatus.