JPH04134504A - Positioning controller - Google Patents

Abstract

PURPOSE:To improve the quick responsiveness of control by moving a rough movement stage and a fine movement stage while simultaneously controlling them and further operating the rough movement stage so that the fine movement stage can be fixed near a set value. CONSTITUTION:When a fine movement stage 3 goes into an area near a target position by moving a rough movement stage 2, a control signal value for fine movement is decreased together with a control signal for rough movement, the fine movement stage 3 moves from the edge to the center, and the rough movement stage 2 decrease the moving speed. When the control signal for fine movement arrives at a dead zone again, this time, the rough movement stage 2 stops and only the fine movement stage 3 continues moving and stops at the target position. Thus, the quick responsiveness of positioning control can be improved.

Description

[Detailed description of the invention] [Industrial application field] The invention of this application relates to a device for controlling position.

More specifically, the invention of this application is a device for controlling a device that performs large movements and precise positioning, such as a precision positioning device for an industrial robot's hand or an adjustment device for an optical system of a laser processing machine. 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 a coarse movement stage and a fine movement stage.

[Prior art] Conventionally, high-precision positioning devices have been known as composite positioning devices that ensure high accuracy by combining a coarse movement stage that can move widely but with low accuracy, and a fine movement stage that moves small but has high accuracy. It is being

As shown in the block diagram of FIG. 5, the control device for such a composite positioning device includes a coarse movement stage 102 that is installed on a substrate 101 and moves on the substrate 101, and a coarse movement stage 102 that is installed on the coarse movement stage 102. a fine movement stage 103 that moves on the coarse movement stage 102, a position detection means 116 that detects the position of the fine movement stage 103, a detected position signal from the position detection means 116, and a positioning target from the target value generation means. The fine movement control means 121 corresponds to the deviation from the value.
and coarse movement control means 131.
08, a coarse movement control means 121 that is selected when the deviation is larger than a predetermined set value and generates a movement control signal for the coarse movement stage 102 corresponding to the deviation, and a coarse movement control means 121 that is selected when the deviation is smaller than a predetermined value. fine movement control means 1 that generates a movement control signal for the fine movement stage 103 corresponding to the deviation;
31, a fine movement drive means 141 for moving the fine movement stage 103 in response to a control signal from the fine movement control means 131, and a coarse movement stage 103 in response to a control signal from the coarse movement control means 131. It is composed of coarse movement driving means 151 for moving.

In controlling this composite positioning device, first, while the fine movement stage 103 is fixed on the coarse movement stage 102,
Rough positioning is performed by moving only the coarse movement stage l port 2 to the vicinity of the target position. Next, when the fine movement stage 103 reaches a predetermined vicinity of the positioning target value, 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, a selection means for conditional branching was essential, so the control system became complicated.

Next, since switching control is performed by the selection means, there is a drawback that control coordination is poor.

In addition, since the control must be switched, the target position cannot be set smoothly when a disturbance occurs, which further deteriorates coordination.

[Object of the Invention] The object of the invention of this application is to improve the coordination of positioning control and provide a control device with a simple configuration, in order to solve the problems of the positioning control device based on the above-mentioned prior art. That is.

[Means for Solving the Problem] In accordance with the above-mentioned object, the configuration of the invention of this application is to solve the above-mentioned problem, as a positioning control device, a positioning control device is provided, which includes a substrate 1, and a coarse control device that moves on the substrate 1. A coarse movement stage 2 for positioning, a fine movement stage 3 for fine positioning by moving on the coarse movement stage 2, a position detection means 16 for detecting the position of the fine movement stage 3, and a position detection means 1 for detecting the position of the fine movement stage 3.
The fine movement control means 21 generates a movement control signal for the fine movement stage 3 in response to the deviation between the output from the fine movement stage 6 and the positioning target value, and the coarse movement stage 2 moves.

[Example] Next, an example of the invention of this application will be described based on FIGS. 1 to 4 as follows.

The control of the basic embodiment will be explained based on FIG.

First, the position of the fine movement stage 3 is detected by the position detection means 16, and then the fine movement control means 21 compares and calculates this detected position signal with the target value from the target value setting means, and Converts it into a fine movement movement control signal that controls the position, etc. This fine movement control signal is transmitted to the fine movement driving means 4.
1, the signal is converted into a fine movement drive signal and the fine movement stage 3 is driven. At the same time, the fine movement control signal is sent to the coarse movement control means 31. The coarse movement control means 31 transmits the fine movement movement control signal,
The fine movement stage 3 is compared with a setting value indicating the position to be established on the coarse movement stage 2 and converted into a coarse movement control signal.

This coarse movement control signal is converted into a coarse movement drive signal by the coarse movement driving means 51, and the coarse movement stage 2 is driven.

The coarse movement stage 2 moves.

[Example] Next, an example of the invention of this application will be described based on FIGS. 1 to 4 as follows.

The control of the basic embodiment will be explained based on FIG.

First, the position of the fine movement stage 3 is detected by the position detection means 16, and then the fine movement control means 21 compares and calculates this detected position signal with the target value from the target value setting means, and Converts it into a fine movement movement control signal that controls the position, etc. This fine movement control signal is transmitted to the fine movement driving means 4.
1, the signal is converted into a fine movement drive signal and the fine movement stage 3 is driven. At the same time, the fine movement control signal is sent to the coarse movement control means 31. The coarse movement control means 31 transmits the fine movement movement control signal,
The fine movement stage 3 is compared with a setting value indicating the position to be established on the coarse movement stage 2 and converted into a coarse movement control signal.

This coarse movement control signal is converted into a coarse movement drive signal by the coarse movement driving means 51, and the coarse movement stage 2 is driven.

Next, a specific example will be described based on FIG. 2. Second
In the figure, l is a substrate on which the coarse movement stage 2 is mounted.

The substrate 1 may be a fixed stand or a movable stand. Reference numeral 2 denotes a coarse movement stage for coarse positioning while moving over the substrate l. 3 is a fine movement stage for moving on the coarse movement stage 2 for accurate positioning. The fine movement stage is supported by the coarse movement stage 2 via a plate spring 4, and is movable in the spring direction.

A corner cube 5 is installed on the fine movement stage 3, and indicates the position of the fine movement stage 3 by reflecting the laser light emitted from the laser interferometer 6 for detecting the position (or distance M). 6 is the position of fine movement stage 3 (
It is a laser interferometer that detects the position (or distance 11) by emitting laser light from the corner cube 5, receiving the reflected light, and detecting the degree of interference. . 7 is a laser interferometer counter that counts laser interference fringes measured by the laser interferometer 6 to detect the position (or distance). In addition, for position detection, the corner cube 5, laser interferometer 6,
In addition to the combination of the laser interferometer counter 7, for example, a glass scale, a magnescale, etc. may be used.

8 is a well-known microcomputer for calculating control signals for driving both the coarse and fine movement stages 2.3. This microcomputer 8 has a laser interferometer counter 7.
The control signals for fine movement and coarse movement are calculated from the position signal from the controller and the target values and set values input in advance.

A solid state actuator driver 9 generates a fine movement drive signal for driving the fine movement stage 3 in response to a control signal from the microcomputer 8. 10 is a coarse movement stage 2 in response to a control signal from a microcomputer 8.
This is a servo amplifier that generates a coarse movement driving means for driving.

A solid actuator 11 moves the fine movement stage 3, and is, for example, a piezoelectric element, a magnetostrictive element, or the like. The movement path if (stroke) of a single piezoelectric element is approximately several tens of μm. A servo motor 12 moves the coarse movement stage 2 by rotating a ball screw 13 and moving a nut 14 as shown. The coarse movement stage 2 moves over 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 explained based on FIG. 3.

The position signal from the laser interferometer 6 is input to the microcomputer 8 via the laser counter 7, and is subjected to the following processing.

The position signal measured by the laser interferometer 6 is input to the fine movement control means 21, and first, the subtraction means 22 compares it with the target value issued from the target value generation means to calculate the deviation.This deviation signal is then made known. Proportional and
Integration and differentiation processing are performed, and the limiter means 24 sets the upper limit and
By limiting the lower limit, fine movement control signals (for example, coarse movement stage 2
control signal for controlling the relative position of the upper fine movement stage 3). The fine movement control signal is input to the solid state actuator driver 9, where it is 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.

Coarse movement control means 3 simultaneously branches the fine movement control signal.
1, and the subtracter 32 performs a comparison operation with the set value E from the set value generating means, and inputs the result to the dead zone means 33. The dead band means 33 outputs zero if the fine movement control signal is within the dead band E1 to E2 near the set value E, and if the value exceeds E+ or El, it outputs a value obtained by subtracting E or El from the input value. Outputs a signal corresponding to

Furthermore, this output signal is amplified by the proportional calculation means 34 and inputted to the servo amplifier IO as a coarse movement control signal to drive the servo motor 12. At this time, as shown in the diagram,
Considering that the operation of the servo motor 12 is unstable in the low rotation range due to the influence of friction, the dither signal from the dither function generating means 36 may be added to the coarse movement control signal by the adding means 37. good.

An example of the operation of this embodiment will be explained based on FIGS. 4(a), (b), and (c). The horizontal axis of the words represents the 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 time change in 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. (C) is a diagram showing a temporal change in a coarse movement control signal value corresponding to, for example, a movement speed control signal of the coarse movement stage.

For the sake of explanation, the above set value E is set to 50%, and the range of the dead zone E1. Let E* be 40% and 60%, respectively.

At the start of control, a signal corresponding to the deviation y between the target value and the actual position of the fine movement stage is first commanded as shown in FIG. 4(a). The fine movement control signal follows this command value with a slight delay as shown in FIG. 4(b). 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 at the initial stage, since it is a dead zone region, the coarse movement control signal value remains at a zero value. That is, initially only the fine movement stage 3 moves and the coarse movement stage 2 is in a stopped state.

The control signal value for fine movement increases and the dead band E2 (60%)
When the coarse movement signal value reaches , the coarse movement signal value rises as shown in FIG. 4(c), and the coarse movement stage 3 starts moving to the target value.

Next, depending on the control variables, as shown in the example shown in Figure 4 (C), the fine movement control signal value saturated to the maximum value of 100%, and the fine movement stage 3 stopped at the end on the target value side. In this state, only the coarse movement stage 2 continues to move.

As the coarse movement stage 2 moves, the fine movement stage 3
When enters the vicinity of the target position, the fine movement control signal value decreases together with the coarse movement control signal, the fine movement stage 3 moves from the edge to the center, and the coarse movement stage 2 decreases in moving speed.

When the fine movement control signal reaches the dead zone E2 value again as shown in Fig. 4 (b), the coarse movement stage 2 stops this time and only the fine movement stage 3 continues to move as shown in Fig. 4 (c). death,
Stop at the target position.

If the dead zones E1 and El are provided near the set value E in this way, the fine movement stage 3 will be able to move around the set value E at El or El.
When this is reached, the coarse movement stage 2 stops and only the fine movement stage 3 is controlled.

[Effect of the invention] Since the invention of this application is configured as described above,
This produces the effects described below.

First, since the coarse movement stage and the fine movement stage move while being controlled simultaneously, there is an effect that the coordination of control is improved. At this time, since the coarse movement stage operates so that the fine movement stage is established near the set value, the coordination of control is improved.

Furthermore, it also has the effect of smoothly establishing the target position in the event of disturbance.

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

Further, if a dead zone is provided, the fine movement stage can be controlled in the vicinity of the target position with the coarse movement stage stopped, so hunting does not occur (there is also the effect that the target position can be established).

[Brief explanation of the drawing]

1 to 4 are detailed explanatory diagrams of the invention of this application, in which FIG. 1 is a circuit diagram of one embodiment of the invention of this application, FIG. 2 is a circuit diagram of another embodiment, and FIG. FIG. 3 is a block diagram of another embodiment, and FIG. 4 is a graph showing changes in signal values in the embodiment. FIG. 5 is a circuit diagram of a conventional mode.

Claims (1)

[Claims] (1) A substrate, a coarse movement stage that moves on the substrate to perform coarse positioning, a fine movement stage that moves on the coarse movement stage to perform fine positioning, and a position detection means that detects the position of the fine movement stage. a fine movement control means for generating a movement control signal for the fine movement stage in response to a deviation between a detected position signal from the position detection means and a positioning target value; a movement control signal for the fine movement stage; and a movement control signal for the fine movement stage; Coarse movement control means that generates a movement control signal for the coarse movement stage based on a set value indicating the established position of the fine movement stage on the stage; and a coarse movement control means that moves the fine movement stage in response to a movement control signal from the fine movement control means. A positioning control device comprising a fine movement drive means for moving the coarse movement stage and a coarse movement drive means for moving the coarse movement stage in response to a movement control signal from the coarse movement control means.