WO2020138705A1

WO2020138705A1 - Control device for gantry stage having deviation control unit

Info

Publication number: WO2020138705A1
Application number: PCT/KR2019/015152
Authority: WO
Inventors: 함년근
Original assignee: 알에스오토메이션주식회사
Priority date: 2018-12-27
Filing date: 2019-11-08
Publication date: 2020-07-02
Also published as: KR102188741B1; KR20200080871A

Abstract

A control device of the present invention comprises: a first control unit having a position control unit which outputs position control values of a first motor for driving one side of an arm of a gantry stage, and a second motor for driving the other side of the arm; a second control unit connected downstream of the first control unit and having a first current control unit which outputs a first current value input to the first motor, and a second current control unit which outputs a second current value input to the second motor; and a deviation control unit for removing a yaw error value of the arm by using a first measurement value obtained by measuring the driving amount of the first motor, and a second measurement value obtained by measuring the driving amount of the second motor.

Description

Control device for gantry stage with deviation control

The present invention relates to a control device for reducing the yaw error value of a gantry stage.

The gantry stage is a rectangular coordinate robot having a gantry as a moving means. A gantry is a gate-shaped structure that itself moves. Gantry stages are used in semiconductor and display processes, and precise driving is required to limit position errors.

[Advanced technical literature]

[Patent Document]

(Patent Document 1) Korean Registered Patent Publication No. 10-0713561

The present invention provides a control device capable of reducing the load on the instrument and improving control precision by minimizing yaw error during driving control of the gantry stage.

The control device of the present invention includes: a first control unit having a position control unit outputting a position control value of a first motor driving one side of the arm of the gantry stage and a second motor driving the other side of the arm; It is connected to the downstream of the first control unit, and includes a first current control unit for outputting a first current value input to the first motor and a second current control unit for outputting a second current value input to the second motor. A second control unit; A deviation control unit for removing a yaw error value of the arm by using a first measurement value measuring the driving amount of the first motor and a second measurement value measuring the driving amount of the second motor; It includes.

In the gantry stage to which the control device of the present invention is applied, a plurality of motors are provided for uniaxial linear motion of a moving part including an arm to suppress yaw or twist of the gantry stage.

The control device of the present invention includes a deviation control unit that receives a first measurement value measuring the driving amount of the first motor and a second measurement value measuring the driving amount of the second motor, thereby suppressing the deviation of the driving amount between each motor. can do.

The control device of the present invention is equipped with a notch filter having a vibration frequency removal function in the deviation control unit for suppressing vibrations generated in the gantry stage during deviation control, so that it is possible to artificially suppress yaw error values.

When quick response is required, when steady-state error suppression is required, when vibration due to the yaw error value is suppressed, vibration of the gantry stage is suppressed by the notch filter, thereby reducing the yaw error value of the deviation control unit. It can be further increased.

On the other hand, since the position control unit and the current control unit are implemented in hardware and on-chip, processing time is reduced.

Therefore, since the position control can be performed within the sampling cycle of the current control unit, the yaw error value can be removed and vibration can be suppressed in real time.

1 is a block diagram showing a control device of the present invention.

2 shows driving logic of the position control unit and the current control unit implemented in hardware of the present invention.

3 is a schematic diagram of a gantry stage to which the control device of the present invention is connected.

4 is a frequency response diagram illustrating the operation of the notch filter of the present invention.

The control device of the present invention includes a first control unit 100, a second control unit 200, and a deviation control unit 170.

The first control unit 100 includes a first motor 311 driving one side of the arm 430 of the gantry stage 400 and a second motor 321 driving the other side of the arm 430 of the gantry stage 400. Can be controlled. The first control unit 100 may include a location control unit 130.

The gantry stage 400 may include an X-axis moving portion, a Y-axis moving portion, and a Z-axis moving portion that reciprocate with respect to each of the orthogonal X-axis, Y-axis and Z-axis linear axes. For example, the X-axis movement unit, the Y-axis movement unit, and the Z-axis movement unit may be an arm 430 (ARM) that moves linearly. One end and the other end of each arm 430 are provided with a motor (311, 321) and a ball screw connected to the motor (311, 321) to provide a linear movement force of each arm (430).

At this time, when the size of the gantry stage 400 increases, torsion may occur depending on the position of the center of gravity of the arm 430 and the point of action of the force of the ball screw with respect to the linear motion of the X, Y, and Z axes. The torsional displacement or torsional moment of the arm 430 may be defined as a yaw. Torsion may occur in proportion to the position or distance of the center of gravity of the arm 430 with respect to the action point. As the gantry stage 400 increases and the movement speed increases, a larger twist may occur. The torsional error may be expressed as a positional error between one end of the arm 430 and the other end, and may be defined as a yaw error or a yaw error value (X1-X2).

For example, when the gantry stage 400 conveys the LCD mother glass, the 10.5 generation mother glass reaches 2.9M in width and 3.1M in length. When forming a pattern printing or the like, the gantry stage 400 needs to be precisely moved without yaw error.

In order to improve the positional accuracy of the gantry stage 400 and reduce yaw errors, a hardware structure in which two

motors

311 and 321 are installed on one arm 430 is preferable. However, this is only a passive reduction means, and a special yaw error reduction means such as the deviation control unit 170 of the present invention is needed as an adaptive control means.

The gantry stage 400 includes

motors

311 and 321 that generate driving force, and

guide portions

410 and 420 that transmit the driving force of the

motors

311 and 321 to the arm 430 and guide linear motion of the arm 430. , It may include an encoder (391, 392) for measuring the driving amount of the motor (311, 321), a servo driver for controlling the motor (311, 321) may include a position control unit 130. The

motors

311 and 321 may be

rotary motors

311 and 321 or

linear motors

311 and 321 that move linearly. Correspondingly, the

encoders

391 and 392 may be sensors that measure a rotation amount or measure linear movement.

In the case of the

encoders

391 and 392 for measuring the rotation amount, at least one of the angular velocity, angular acceleration, rotation angle, and rotation number of the

motors

311 and 321 may be measured as the driving amount. In the case of the

encoders

391 and 392 for measuring the linear movement amount, at least one of the distance, movement speed, and acceleration of movement of the arm 430 may be measured as the driving amount. The measured value measured by the driving amount may be fed back to the position control unit 130 or the deviation control unit 170.

For example, FIG. 3 shows the rotation angle or position as the measurement values X1 and X2. In order to increase precision in terms of hardware, the first motor 311 drives one side of the arm 430 of the gantry stage 400, and the second motor 321 moves the other side of the arm 430 of the gantry stage 400. I can drive it. The position control unit 130 or the deviation control unit 170 may be provided to increase precision from a software perspective.

The position command values P* of the

motors

311 and 321 or the arm 430 as control targets of the first motor 311 and the second motor 321 may be input to the position controller 130.

The first calculation unit 110 calculates a value obtained by subtracting the average of the first measurement value X1 and the second measurement value X2 from the position command value P* as the position error value Pos_err, and the position control unit ( The location error value Pos_err may be input to 130). The position command value P* and the position error value Pos_err may be common values that are not classified for each of the first motor 311 and the second motor 321. The command value input to the position control unit 130 and the control value output from the position control unit 130 may not be classified for each of the first motor 311 and the second motor 321.

In this state, in order to remove the yaw error value (X1-X2) of the arm 430, it is necessary to input a command value classified for each

motor

311 and 321. If the subtracted value of the output of 170) and the added value are separately input to each of the

motors

311 and 321, rapid removal of the yaw error value X1-X2 may be possible.

A value obtained by subtracting the output of the deviation control unit 170 from the output of the location control unit 130 may be input to the first motor 311. A value obtained by adding the output of the deviation control unit 170 to the output of the location control unit 130 may be input to the second motor 321.

The feed forward unit 120 may be added to the first control unit for rapid removal of the position error value Pos_err. The feed forward unit 120 may receive the position command value P* and output the position estimation value to the second calculation unit 140. The second calculation unit 140 may add the output of the feed forward unit 120 to the output of the location control unit 130. The output of the second calculator 140 may be input to the first branch 150 and the second branch 160 as common values.

The second control unit 200 may include

current control units

220a and 220b for forcing control or current control of each of the

motors

311 and 321. The

current controllers

220a and 220b may input command values (Current 1 and Current 2) classified for each

motor

311 and 321. A first current control unit 220a may be provided for thrust control of the first motor 311 or current control of the first motor 311. A second current control unit 220b may be provided for thrust control of the second motor 321 or current control of the first motor 311.

The second control unit 200 may transmit values classified for each of the

motors

311 and 321. The second control unit 200 includes a first speed control unit 210a connected downstream of the first control unit 100 and a first current control unit connected between the first speed control unit 210a and the first motor 311. It may be provided (220a). The second control unit 200 includes a second speed control unit 210b connected downstream of the first control unit 100 and a second current control unit connected between the second speed control unit 210b and the second motor 321. It may be provided (220b).

The deviation control unit 170 may generate an output for removing the yaw error value X1-X2 of the arm 430. The input of the deviation control unit 170 is a first encoder 31 that measures the driving amount of the first motor 311, a first measurement value (X1), and a second encoder that measures the driving amount of the second motor 321 The second measurement value X2 of 392 may be input to the deviation control unit 170. The yaw error value X1-X2 may be directly input to the deviation control unit 170, and the yaw error value (within the deviation control unit 170) using the first measurement value X1 and the second measurement value X2. X1-X2) can be calculated. The deviation control unit 170 may perform a control operation for removing the yaw error value X1-X2 of the arm 430 using the first measurement value X1 and the second measurement value X2.

In one-way movement of the arm 430, when a plurality of

motors

311 and 321 are used as a power source for the same movement, each of the

motors

311 and 321 must be controlled with the same driving amount. However, even if the same control values are input to each of the

motors

311 and 321, the

individual motors

311 and 321 are difficult to control at the same position and speed, and deviations in position or speed may occur. Even if the

motors

311 and 321 and the ball screw are configured in the same model, a difference may occur in the actual driving due to the tolerance of each component. In addition, since the load applied to each of the

motors

311 and 321 varies depending on the eccentricity of the mass that the arm 430 conveys, the actual driving amount of each

motor

311 and 321 may vary.

Therefore, it is preferable that the final control value for which the driving amount deviation value is corrected is input to each of the

motors

311 and 321. The deviation control unit 170 calculates a yaw error value X1-X2 corresponding to the difference between the first measurement value X1 and the second measurement value X2, and the speed corresponding to the yaw error value X1-X2 The correction value can be output.

The first speed command value obtained by subtracting the speed correction value, which is the output of the deviation control unit 170, from the speed control value, which is the output of the position control unit 130 or the output of the second calculation unit 140, and the output of the position control unit 130 Alternatively, if the second speed command value obtained by adding the speed correction value, which is the output of the deviation control unit 170, to the speed control value, which is the output of the second output unit 140, is input separately to each

motor

311, 321, the yaw error value (X1-X2) can be removed quickly.

The deviation control unit 170 may include a notch filter 175. Meanwhile, the deviation control unit 170 may further include a gain setting unit 171 and a limiting unit 173. From the input side to the output side of the deviation control unit 170, the gain setting unit 171, the limiting unit 173, and the notch filter 175 may be sequentially connected.

The notch filter 175 illustrated in FIG. 4 resonates with respect to at least one of the first measurement value X1, the second measurement value X2, and the difference between the first measurement value X1 and the second measurement value X2 Components of a specific frequency band corresponding to frequencies can be removed. The notch filter 175 may reduce components of a specific frequency band including the resonance frequency of the first motor 311, the second motor 321, or the arm 430.

The first branch unit 150 may subtract the output of the notch filter 175 from the output of the position control unit 130 and transmit it to the first speed control unit 210a or the first current control unit 220a. The first branch unit 150, the first speed control unit 210a and the first current control unit 220a may be connected to the first motor 311.

The second branch unit 160 may add the output of the notch filter 175 to the output of the position control unit 130 and transmit it to the second speed control unit 210b or the second current control unit 220b. The second branch unit 160, the second speed control unit 210b and the second current control unit 220b may be connected to the second motor 321.

The value obtained by subtracting the output of the notch filter 175 from the output of the position control unit 130 and the value obtained by adding the output of the notch filter 175 to the output of the position control unit 130 are the first motor 311 and the second motor 321. ). The output of the notch filter 175 is a control component that reduces the yaw error value X1-X2 or a control component that eliminates resonance of the arm 430. Therefore, when the value obtained by subtracting the output of the notch filter 175 from the common output of the position control unit 130 and the added value are separately input to the first motor 311 and the second motor 321, the yaw error value X1- X2) can be quickly removed, and resonance of the arm 430 can be quickly removed.

The gain setting unit 171 may multiply the difference between the first measurement value X1 and the second measurement value X2 or the yaw error value X1-X2.

The limiting unit 173 may limit the upper limit or the lower limit so that the response of the arm 430 does not diverge by inputting the yaw error value X1-X2. The limiting unit 173 may be provided between the gain setting unit 171 and the notch filter 175. The limiter 173 may limit the upper limit or the lower limit of the value input from the gain setting unit 171 to the notch filter 175.

Meanwhile, the location control unit 130 or the second control unit 200 may be implemented by hardware logic to operate in real time. The chip configuration unit 500 may include at least a position control unit 130, a first current control unit 220a, and a second current control unit 220b. The chip component 500 may be implemented as a hardware circuit in a microchip.

Referring to FIG. 2, the output of the position control unit 130 may be generated or the control operation of the position control unit 130 may be completed within the sampling cycles of the first current control unit 220a and the second current control unit 220b.

The sampling periods of the first current control unit 220a and the second current control unit 220b may be the same, and may be started or ended at the same sampling time. The illustrated control cycle means the sampling cycle of the

current controllers

220a and 220b. One control period of the position control unit 130 may be completed within one control period or one sampling period of the

current control units

220a and 220b, or one control period of the deviation control unit 170 may be completed. The control operation of the position control unit 130 or the control operation of the deviation control unit 170 may be completed within the control period or the sampling period of the

current control units

220a and 220b.

Within the control period of the

current control units

220a and 220b, the location control unit 130 may request location information. Within the control period of the

current control units

220a and 220b, the location control unit 130 may obtain location information P*, X1, and X2. The position control unit 130 may perform a position control operation according to the acquired location information and transmit the speed control value to the second control unit 200. The speed control values may be classified for each of the

motors

311 and 321 and may be input to the first speed control unit 210a and the second speed control unit 210b, respectively. The notch filter 175 of the deviation control unit 170 within the control period of the

current control units

220a and 220b is the current to be input to the

speed control units

210a and 210b or the

current control units

220a and 220b of the second control unit 200. Alternatively, the speed command value can be filtered.

(Explanation of codes)

100... first control unit 110... first calculation unit

120...feed forward 130...position control

140... second calculation unit 150... first quarter

160...second branch 170...deviation control

171...Gain setting section 173...Limitation section

175...notch filter 200...second control

210a, 210b... speed control unit 210a... first speed control unit

210b... second

speed control unit

220a, 220b... current control unit

220a... first current control unit 220b... second current control unit

311...first motor 321...second motor

391...first encoder 392...second encoder

400...

Gantry stage

410, 420...Guide section

430...arm 500...chip components

X1...first measured value

X2...2nd measured value P*...position command value

Claims

A first control unit having a position control unit outputting a position control value of a first motor driving one side of the arm of the gantry stage and a second motor driving the other side of the arm;

It is connected to the downstream of the first control unit, and includes a first current control unit for outputting a first current value input to the first motor and a second current control unit for outputting a second current value input to the second motor. A second control unit;

A deviation control unit for removing a yaw error value of the arm by using a first measurement value measuring the driving amount of the first motor and a second measurement value measuring the driving amount of the second motor; Control device comprising a.
According to claim 1,

The deviation control unit,

A control device having a notch filter for removing a component of a specific frequency band corresponding to a resonance frequency with respect to at least one of the first measurement value, the second measurement value, and the difference between the first measurement value and the second measurement value .
According to claim 2,

A first branch unit subtracting the output of the notch filter from the output of the position control unit;

A second branch unit for adding the output of the notch filter to the output of the position control unit; Including,

The first branch part and the first current control part are connected to the first motor,

The second branch and the second current control unit is a control device connected to the second motor.
According to claim 3,

The deviation control unit,

A gain setting unit for multiplying the difference between the first measurement value and the second measurement value by a gain;

A control device provided between the gain setting unit and the notch filter and having a limiting unit for limiting an upper limit or a lower limit of a value input from the gain setting unit to the notch filter.
According to claim 1,

A notch filter is provided at a rear end of the deviation control unit,

The notch filter reduces a component of a specific frequency band including the resonance frequency of the first motor, the second motor, or the arm,

A control device for subtracting the output of the notch filter from the output of the position control unit and a value obtained by adding the output of the notch filter to the output of the position control unit is input to the first motor and the second motor, respectively.
According to claim 1,

A position error value is input to the position control unit,

The position error value is a value obtained by subtracting the average of the first measured value and the second measured value from a position command value, and is a common value that is not classified for each of the first motor and the second motor,

A value obtained by subtracting the output of the deviation control from the output of the position control is input to the first motor,

A control device in which a value obtained by adding the output of the deviation control unit to the output of the position control unit is input to the second motor.
According to claim 1,

The second control unit,

A first speed controller connected downstream of the first controller,

The first current control part connected between the first speed control part and the first motor,

A second speed controller connected downstream of the first controller,

And a second current control unit connected between the second speed control unit and the second motor.
According to claim 1,

The chip component includes the position controller, the first current controller, and the second current controller,

The chip component is a control device implemented as a hardware circuit on a microchip.
According to claim 1,

A control device for generating outputs of the position control unit within a sampling period of the first current control unit and the second current control unit.