JPH0981243A - Fine positioning controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To finely adjust the control performance of respective motion modes of a fine positioning mechanism without increasing cost. SOLUTION: This fine positioning controller is provided with a positioning object 1 with one degree of freedom for translation and two degrees of freedom for rotation, actuators 2 (M, R, L) for driving the object 1, position sensors 3 (M, R, L) for measuring the displacement of the object 1, a motion mode extracting circuit 9 for applying prescribed operation to output signals obtained by amplifying deviation signals between feedback signals from the sensors 3 and command voltage values 5 (M, R, L) and extracting plural operation mode-sorted deviation signals for the positioning object 1, compensators 7 (M, R, L) for independently compensating respective output, a motion mode distributing circuit 10 for generating driving signals for respective actuators 2 by applying prescribed operation to output signals from the compensators 7, and power amplifiers 8 (m, R, L) for driving the actuators 2 in accordance with the driving signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine movement positioning control device for positioning an object to be positioned at a predetermined position in a predetermined posture.

[0002]

2. Description of the Related Art FIG. 3 shows the configuration of a conventional fine movement positioning control device for positioning and controlling one degree of freedom in the vertical direction and two degrees of freedom of inclination in a horizontal plane. In the figure, 1 is a flat plate substrate to be positioned, 2M, 2R and 2L are actuators that generate displacement of the substrate 1 in the vertical direction. Each actuator uses a piezoelectric element as a drive element, and also includes a displacement magnifying mechanism. . 3M, 3R and 3L are actuators 2
A position sensor that is located near M, 2R, and 2L and that measures the displacement of the substrate 1 in the vertical direction. The mechanism including the substrate, the actuator and the position sensor will be referred to as a fine movement positioning mechanism.

4M, 4R and 4L are position sensors 3M,
Displacement amplifiers 5M, 5R and 5L for converting the vertical displacement of the substrate 1 measured by 3R and 3L into electric signals are command inputs, and e _M , e _R and e _L are outputs of the displacement amplifiers 4M, 4R and 4L. Of the position deviation signals output by comparing the command inputs 5M, 5R and 5L with 6M, 6
R and 6L are deviation amplifiers for amplifying the position deviation signals e _M , e _R and e _L , and 7M, 7R and 7L are for the deviation amplifiers 6M, 6R and 6L in order to stabilize the control loop and zero the position deviation signal. Compensator with output as input, 8
The outputs of the compensators 7M, 7R, and 7L are input to M, 8R, and 8L, and the actuators 2M, 2R, and 2L are moved up and down to translate the substrate 1 in the vertical direction and incline it to the vertical direction. It is a power amplifier that drives. A closed loop composed of these displacement amplifiers 4M, 4R and 4L to power amplifiers 8M, 8R and 8L will be referred to as a feedback device.

The above-described fine movement positioning mechanism and feedback device will be referred to as a fine movement positioning control device.

FIG. 4 shows the configuration of an apparatus in which the control characteristics of the fine movement positioning control apparatus of FIG. 3 are improved. This device was applied for in Japanese Patent Application No. 6-132405.

This device is obtained by newly adding a motion mode extraction circuit 9 and a motion mode distribution circuit 10 to the configuration of the fine movement positioning control device of FIG. Position sensor 3
Vertical Z of substrate 1 measured by M, 3R and 3L
The axial displacement is converted into displacement signals z _M , z _R and z _L by displacement amplifiers 4M, 4R and 4L. This signal is input to the motion mode extraction circuit 9 and becomes motion mode displacement signals z _g , zθ _x, and zθ _y . Here, the calculation of the motion mode extraction circuit 9 follows the equation (1).

[0007]

[Equation 1] In a general positioning control device, when extracting a motion mode of a positioning object, a motion mode extraction circuit is generally arranged in a feedback loop.

The motion mode displacement signals z _g , zθ _x and zθ _y are motion mode command inputs 5M ', 5R' and 5 respectively.
It is compared with L ′, and as a result, the motion mode deviation signal e
_g , eθ _x and eθ _y are obtained. This motion mode-specific error signal e _g, E.theta _x and E.theta _y are input to obtain a predetermined sensitivity deviation amplifier 6M, the 6R and 6L. Further, the outputs of the deviation amplifiers 6M, 6R and 6L are
Compensator 7M for adjusting the control loop for each motion mode,
It is input to 7R and 7L, and thereby, the motion mode compensation signals c _g , cθ _x, and cθ _y regarding the position are obtained. Motion mode compensation signals c _g , c θ _x and c θ _y
Are input to the motion mode distribution circuit 10. The motion mode distribution circuit 10 outputs drive signals d _M , d _R and d _L for the respective axes, which drive the power amplifiers 8M, 8R and 8L. Here, the calculation of the motion mode distribution circuit 10 follows Formula 2.

[0009]

[Equation 2] As described above, the one in which the motion mode extraction circuit 9 and the motion mode distribution circuit 10 are newly inserted in the feedback device of the fine movement positioning control device of FIG. A fine movement positioning decoupling device including an interfering feedback device will be called.

Equations 1 and 2 are for the actuator 2M,
In the coordinate system showing the arrangement of 2R and 2L and the position sensors 3M, 3R and 3L, translational movement of the substrate 1 and rotational movement in the plane are defined with respect to the origin of this coordinate. Therefore, when the arrangements of the actuators 2M, 2R and 2L and the position sensors 3M, 3R and 3L change, the calculations of the motion mode extraction circuit 9 and the motion mode distribution circuit 10 change. FIG. 5 shows a coordinate system showing the arrangement of the actuators 2M, 2R and 2L and the position sensors 3M, 3R and 3L. Expressions 1 and 2 represent the arithmetic expressions of the motion mode extraction circuit 9 and the motion mode distribution circuit 10 in this coordinate system.

According to this fine movement positioning decoupling device,
It is possible to adjust the loop gain for each motion mode of the substrate 1. The fine movement positioning control device in FIG. 3 can only adjust the loop gain for translational movement in the Z-axis direction,
The fine movement positioning decoupling device of FIG. 4 can pursue control characteristics to the limit as much as the degree of freedom in adjustment increases.
Not only the response to the command input can be improved, but also the disturbance suppression performance is improved.

[0012]

However, according to the above-mentioned conventional fine movement positioning control device, mechanical resonance of the mechanism is stimulated when the control loop gain is sequentially increased in order to maximize the positioning time and the disturbance suppression performance. Therefore, there is a limit to the performance improvement. Further, when the gain is adjusted, the translational motion mode out of the translational 1 degree of freedom and the two rotary motions is consciously operated. It becomes a subordinate decision method. That is, there is a problem that the control performance of each motion mode of the triaxial fine movement mechanism cannot be finely adjusted.

Further, according to the conventional fine movement positioning decoupling device, since the output signals of the displacement amplifiers 4M, 4R and 4L are inputted to the motion mode extraction circuit 9, the motion mode extraction circuit 9 is constructed by hardware. In that case, the position of the fine movement positioning mechanism cannot be accurately detected due to the influence of the gain error due to the drift due to the temperature change of the resistor and the error in the resistance value. Therefore, it is necessary to use a highly accurate resistor or component to reduce the influence of temperature drift and resistance value error, resulting in a problem that the cost of the device increases.

In view of the above problems of the prior art, an object of the present invention is to enable the fine movement positioning device to finely adjust the control performance of each movement mode of the fine movement positioning mechanism without increasing the cost. Especially.

[0015]

In order to achieve the above object, according to the present invention, a positioning object positioned in one translational degree of freedom and two rotational degrees of freedom, and three actuators for driving the positioning object. And three position sensors that measure the displacement of the positioning object in the vicinity of each actuator, and the deviation signal between the feedback signal and the command voltage by the output of each position sensor, and based on this, through the deviation amplifier and the compensator. In a fine movement positioning device including a feedback device for driving an actuator by a power amplifier, a motion mode in which a deviation signal for each motion mode of a plurality of motion modes regarding a positioning object is extracted by performing a predetermined calculation on an output signal of the deviation amplifier. Compensates independently for each output of the extraction circuit and the motion mode extraction circuit. A compensator, a motion mode distribution circuit that performs a predetermined calculation on the output signals of these compensators to generate drive signals for each actuator, and a power amplifier that drives the actuators according to the drive signals. To do.

The compensator is a circuit for adjusting the gain, and the power amplifier is a current output type power amplifier.

Further, a PI compensator for performing proportional-plus-integral compensation on the output of the motion mode distribution circuit is provided, and the power amplifier is a voltage output type power amplifier.

[0018]

In this structure, the deviation signal between the signal from each position sensor and the command voltage is amplified by the deviation amplifier, and the deviation signal for each movement mode is extracted from the signal in the movement mode extraction circuit. Then, the extracted deviation signal for each motion mode is independently compensated, and thereafter distributed by the motion mode distribution circuit to be a drive signal for each actuator. At that time, the deviation signal input to the motion mode extraction circuit is 0 near the completion of positioning.
Since it approaches the voltage, even if the motion mode extraction circuit is configured by hardware, the influence of the gain error due to the drift due to the temperature change of the resistor and the error of the resistance value is negligible. Therefore, it is not necessary to use a highly accurate resistor or component for coping with such a gain error, and fine compensation is performed for the control performance of each motion mode of the three-axis fine movement mechanism by each actuator.

[0019]

【Example】

[Embodiment 1] FIG. 1 is a diagram showing the configuration of a fine movement positioning control apparatus according to a first embodiment of the present invention, and best shows the features of the present invention. In the figure, b _M , b _R and b _L are deviation amplification signals, and b _g , bθ _x and bθ
_y is the deviation amplification signal for each motion mode. Other Figure 3
And the same reference numerals as in FIG. 4 indicate the same elements as those in those figures.

The operation of the apparatus shown in FIG. 1 will be described below.

The displacements of the substrate 1 in the vertical Z-axis direction measured by the position sensors 3M, 3R and 3L are converted into displacement signals z _M , z _R and z _L by the displacement amplifiers 4M, 4R and 4L. The displacement signals z _M , z _R and z _L are compared with the command input signals 5M, 5R and 5L to obtain position deviation signals e _M , e _R and e _L. This position deviation signal is input to the deviation amplifiers 6M, 6R and 6L in order to obtain a predetermined sensitivity, and the deviation amplification signals b _M , b _R and b _L are inputted.
Becomes The deviation amplification signals b _M , b _R, and b _L are input to the motion mode extraction circuit 9, and the motion mode deviation amplification signals b _g , bθ _x, and bθ _y are extracted. Here, the calculation of the motion mode extraction circuit 9 can be expressed by Equation 3.

[0022]

(Equation 3) Next, the motion mode deviation signals b _g , bθ _x, and bθ _y
Is a compensator 7 that adjusts the control loop for each motion mode.
It is input to M, 7R and 7L and becomes the motion mode-based compensation signals c _g , cθ _x and cθ _y regarding the position. The motion mode compensating signals c _g , cθ _x, and cθ _y are input to the motion mode distribution circuit 10 to drive signals d to the respective axes.
_M , d _R and d _L , and actuators 2M and 2R
Current output type power amplifiers 8M, 8
Drive R and 8L. The arithmetic expression of the motion mode distribution circuit 10 is the same as the mathematical expression 2.

As a result, compared with the conventional fine movement positioning control device, the loop gain can be adjusted for each motion mode of the substrate 1, the control characteristics of the device can be pursued to the limit, and the response to the command input can be improved. Not only can it be improved, but the disturbance suppression performance is also improved.

Further, as compared with the conventional fine movement positioning decoupling device, when the motion mode extraction circuit 9 and the motion mode distribution circuit 10 are realized by hardware, the position deviation signals e _M , e _R and e at the start of positioning. _L is large, but position deviation signals e _M , e _R
And the voltage of e _L are near 0 [V], and as a result, the input signal voltage to the motion mode extracting circuit 9 is also near 0 [V], and drift due to temperature change of the resistor in the motion mode extracting circuit 9 and The effect of gain error due to resistance error can be ignored.

In this embodiment, a current output type power amplifier 8 is used.
Since M, 8R, and 8L are used and the response to the target value of the entire control system is a first-order lag, it is possible to adjust the response so that overshoot does not occur by adjusting the loop gain. It has the feature that it does not burden the positioning mechanism.

[Second Embodiment] In the first embodiment, a current output type is used as a power amplifier. However, current output type power amplifiers are rarely used for the actuators 2M, 2R and 2L such as piezoelectric elements, and in general, voltage output type power amplifiers are often used. This is because when the control system loop is opened and a constant input voltage is applied to the current output type power amplifier, the voltage across the piezoelectric element increases with time.

Therefore, a second embodiment in which the power amplifier is of the voltage output type is shown in FIG. In the figure, 17M, 17
R and 17L are PI compensators, and 18M, 18R and 18L are voltage output type power amplifiers. here,
P means proportional operation and I means integral operation. Elements indicated by other reference numerals are the same as those in FIG.

As a result, as compared with the conventional fine movement positioning control device, the loop gain can be adjusted for each motion mode of the substrate 1, the control characteristics of the device can be pursued to the limit, and the response to the command input can be improved. Not only can it be improved, but the disturbance suppression performance can also be improved.

Further, as compared with the conventional fine movement positioning decoupling device, when the motion mode extraction circuit 9 and the motion mode distribution circuit 10 are realized by hardware, the position deviation signals e _M , e _R and e at the start of positioning. _L is large, but position deviation signals e _M , e _R
And the voltage of e _L are near 0 [V], and as a result, the input signal voltage to the motion mode extracting circuit 9 is also near 0 [V], and drift due to temperature change of the resistor in the motion mode extracting circuit 9 and The effect of gain error due to resistance error can be ignored.

In this embodiment, a voltage output type power amplifier is used, and PI compensators 17M, 17R and 17L are used.
Of the voltage output type power amplifiers 18M, 18R and 18L are canceled so that the transfer function from the PI compensators 17M, 17R and 17L to the actuators 2M, 2R and 2L is delayed by the first order. Since the characteristics can be adjusted so that the characteristics of the piezoelectric element itself can be measured by opening the loop of the control system.

[0031]

As described above, according to the present invention, since the motion mode is extracted and compensated for the deviation signal, the control performance of each motion mode of the three-axis fine movement mechanism is finely adjusted. The positioning control characteristics can be improved by adjustment, and it is not necessary to use a highly accurate resistor or component, and cost increase can be avoided. Further, since the command input to the fine movement positioning decoupling device in FIG. 4 is a command for the displacement signal for each motion mode, it is necessary to newly develop software for that.
Since the command input to the fine movement positioning control device of the present invention is a command for the displacement signal as in the conventional FIG. 3 device, the software for driving the fine movement positioning control device of the present invention is
The conventional software for driving the apparatus of FIG. 3 can be used, and the time for software development can be saved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a fine movement positioning control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a fine movement positioning control device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional fine movement positioning control device.

FIG. 4 is a block diagram showing a configuration of a conventional fine movement positioning decoupling device.

FIG. 5 is a diagram showing a coordinate system showing an arrangement of actuators and position sensors in a fine movement positioning device.

[Explanation of symbols]

1: substrate, 2M, 2R, 2L: actuator such as piezoelectric element, 3M, 3R, 3L: position sensor, 4M, 4R,
4L: displacement amplifier, 5M, 5R, 5L: command input, 5M
', 5R', 5L ': Command input for each motion mode, 6M, 6
R, 6L: deviation amplifier, 7M, 7R, 7L: compensator, 8
M, 8R, 8L: current output type power amplifier, 9: motion mode extraction circuit, 10: motion mode distribution circuit, 17M, 1
7R, 17L: PI compensator, 18M, 18R, 18L:
Voltage output type power amplifier, e _M , e _R , e _L : position deviation signal, e _g , e _{θ x} , e _{θ y} : motion mode deviation signal,
z _M , z _R , z _L : displacement signal, z _g , z θ _x , z θ _y :
Displacement signal for each motion mode, b _M , b _R , b _L : Deviation amplification signal, b _g , bθ _x , bθ _y : Deviation amplification signal for each motion mode, c _g , cθ _x , cθ _y : Compensation signal for each motion mode, d
_M , d _R , d _L : Drive signal to each axis.

Claims (3)

[Claims] 1. A positioning object positioned in translational 1 degree of freedom and rotation 2 degrees of freedom, three actuators for driving the object for the positioning, and in the vicinity of each actuator of the positioning object. Three position sensors that measure displacement, and a feedback signal based on the output of each of the position sensors and a deviation signal between the command voltage, and based on this, feedback that drives the actuator by a power amplifier via a deviation amplifier and a compensator. A fine motion positioning device including a device, a motion mode extraction circuit that performs a predetermined calculation on the output signal of the deviation amplifier to extract motion mode deviation signals of a plurality of motion modes related to the positioning object; Compensator for independently compensating each of a plurality of outputs of a mode extraction circuit A motion mode distribution circuit that performs a predetermined calculation on the output signals of these compensators to generate drive signals for the respective actuators, and the power amplifier that drives the actuators according to the drive signals. Fine movement positioning control device. 2. The fine movement positioning control device according to claim 1, wherein the compensator is a circuit for performing gain adjustment, and the power amplifier is a current output type power amplifier. 3. The fine movement positioning according to claim 1, further comprising a PI compensator for performing proportional-plus-integral compensation on the output of the motion mode distribution circuit, and the power amplifier is a voltage output type power amplifier. Control device.