JPS61109115A - Position controller - Google Patents

Abstract

PURPOSE:To shorten a position matching time by stopping the integrating action of an integration means at the beginning of position control and then restarting said integrating action when a traveling object gets close to a target position and the difference between the deviation value of the traveling object and the reference value is smaller than the prescribed value. CONSTITUTION:A servo circuit integrates the deviation signal (c) between the target position signal (a) of a traveling object and the present position signal (b) fed from a position detector 34 through an integrator 31. Then the servo circuit drives a servo motor 33 according to the output amplitude and the polarity of the integrator 31. Thus the traveling object is moved to a target position. Here an operational amplifier 1 to which the signal (c) is supplied is provided at the preceding stage of a servo amplifier 32. The amplifier 1 is connected selectively to a capacitor C and a resistance R by the switching actions of a switch 2. Then the integrator 31 and the amplifier 1 are selectively actuated. The switch 2 selects the integrator 31 with a setting action of a flip-flop FF and then selects the amplifier 1 in a resetting mode of the FF. Thus the FF is set for start of the actuation of the integrator 31 when the traveling object gets close to the target position and the signal (c) is set at a level less than the reference voltage V0.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a till device for controlling the position of a moving body in an XY stage, an Regarding the improvement of

(Key Points of the Invention) The content of this invention is to set the integral operation range to the minimum necessary range when performing an integral operation to settle a moving body driven by servo Tanabata to a target position. do.

(Prior art and its problems) 3 shows a conventional servo circuit.

This servo circuit generates a deviation signal (voltage) C between the target position signal (W pressure) a of the moving body produced by the conventional setting means and the current position signal (electronic) a of the moving body outputted by the position detector 34. An integrator 31 performs integration, and an amplifier 32 drives a servo motor 33 in accordance with the output amplitude and polarity of the integrator 31, thereby operating to move the movable body to a target position.

As is well known, the integral compensation performed in this one-large-one-bore circuit is to eliminate steady position deviation, and the integral value A until the moving object reaches the target position,
This is a compensation in which the difference between the integral value B of the moving object l and the integral value B of r when the moving object passes the target position and is pulled back to the target position is set to O.

However, in the conventional servo circuit, the integral compensation operation is performed from the start of the position control operation, so as shown in Fig. 4, the integral value A1 at the beginning of the position control is quite large. Shino becomes.

Therefore, the integral value B1 corresponding to the integral value B1 becomes considerably large, resulting in a problem that so-called overshoot becomes large and the settling time becomes long.

(Objective of the Invention) The object of the present invention is to shorten the settling time by reducing the overshoot.

(Structure and Effects of the Invention) In order to achieve the above object, the position control l according to the present invention
The device includes an integrating means that performs an integral operation on the difference between the target position and the current position of the moving body driven by a servo motor, and an output state that is reversed when the difference between the deviation value and the reference value is less than a predetermined value. and integrating operation start point control means for causing the integrating means to start an integrating operation starting from the first output inversion operation of the comparing means.

According to this configuration, at the beginning of position control, since the difference between the deviation value and the reference value is greater than the predetermined value, the comparing means does not invert the output state and the integrating means does not perform an integrating operation.

When the moving object approaches the target position and the difference between the M difference 11 and the reference value becomes less than a predetermined value, the comparing means reverses the output state, and the integrating means starts an integrating operation.

Therefore, since the integral value at the target position is small, the overshoot is also small and the settling time can be shortened.

(Description of Embodiments) FIG. 1 shows an example of a servo circuit included in a position control device according to the present invention.

Incidentally, the same parts as in the prior art are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, the operational amplifier 1, which is located in front of the servo amplifier 32 and receives the deviation voltage C, operates as an integrator when the capacitor C is connected, and when the resistor R is connected, by the switching operation of the switch 2. When it is turned on, it operates as a simple amplifier.

The switch 2 causes the operational amplifier 1 to operate as an integrator when the flip-flop FF is set, and causes the operational amplifier 1 to operate as a simple amplifier when the flip-flop FF is reset.

The flip 7O knob FF is set manually by the comparator 3.
The output of is given.

The comparator 3 inverts the output state when the difference between the differential voltage C and the Ml voltage Vo is less than a predetermined value, and the flip 70 tube FF is set by the first output inversion operation. Note that the reset condition for the flip-flop FF is at the start of the position subsection operation or at the completion of the settling operation.

With this configuration, the comparator 2 does not invert its output state at the time when the moving object starts moving toward the target position, so the switch 2 causes the operational amplifier 1 to operate as a simple amplifier.

The moving object approaches the target position, and the deviation voltage C becomes the reference voltage V.

When it becomes smaller, comparator 3 inverts its output. As a result, the 7-lip flop FF is set, so that the operational amplifier 1 starts operating as an integrator by the changeover switch 2.

As a result, as shown in FIG. 2, the operational amplifier 1 performs the integration operation with the point P as the starting point of the integration operation, so that the integral value {circle around (2)} becomes extremely small.

Therefore, the integral value of the overshoot portion corresponding to this becomes smaller, and the settling time is greatly shortened.

[Brief Description of the Drawings] Fig. 1 is a circuit diagram showing an embodiment of a servo circuit included in a position control device according to the present invention, and Fig. 2 is a diagram illustrating an integral compensation operation of the above embodiment device. FIG. 3 is a circuit diagram showing a servo circuit in a conventional position control device, and FIG. 4 is a diagram illustrating the integral compensation operation of the conventional device. 1... Actual amplifier 2... Switch 3... Comparator 32... - Bo amplifier 33... Servo motor 34... Position detector FF... Flip 70, knob a...・Target position signal b...Current position signal C...Difference value signal Patented by Tateishi Densho Co., Ltd. Figure 2

Claims (1)

[Claims] (1) Integrating means for performing an integral operation on the deviation between the target position and the current position of a moving body driven by a servo motor, and comparing means for reversing the output state when the difference between the deviation value and the reference value is less than a predetermined value. . A position control device comprising: integral operation start point control means for causing the integrating means to start an integrating operation starting from a first output reversal operation of the comparing means.