JP2006190074A - Synchronization control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To synchronize two axes through synchronization control whereby synchronization errors of position and speed between the two axes are minimized, even if disturbance is applied to either the first or second axis or if the amount of friction differs greatly between the two axes; and to achieve synchronization of not only speed feedback but also position feedback, whether in a steady state or in a transient state. <P>SOLUTION: This synchronization control apparatus having a position control means using the position feedback of each axis includes a feed forward control part that creates a feed forward signal of each axis based upon position commands; a synchronization error computing part for computing a synchronization error based upon the difference in position feedback between the two axes; a position correction signal computing part for computing a position correction signal based upon the synchronization error computed; a feed forward correction signal computing part for computing a feed forward correction signal of each axis based upon the feed forward signal and the position correction signal of each axis; and an adding part for adding the feed forward correction signal to a speed command. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a synchronous control device that performs control so as to minimize a synchronization error between position and speed between two axes.

  In recent years, twin drive drive that drives one axis of a table with two motors has been used in electronic component mounting apparatuses and liquid crystal manufacturing apparatuses. In the case of such a device, high speed / high acceleration / deceleration driving is required, and quietness, low vibration, and low ripple are also required. If the synchronization error between the two axes is large, it may cause abnormal noise or vibration during driving, and the request cannot be satisfied. To achieve high speed, high acceleration / deceleration drive, quietness, low vibration, and low ripple, synchronization between the two axes is necessary. However, when the dynamic characteristics between the axes are different, each axis is controlled individually. However, there are limitations in the conventional feedback control device. Therefore, a synchronization control device that performs synchronization between the two axes is required.

  The conventional synchronous control device performs speed control using the average value of the speed feedback between the two axes, obtains the correction torque using the speed difference between the two axes, corrects the torque of both motors, and performs the synchronous control. (For example, refer to Patent Document 1). In some cases, the position correction value is obtained by multiplying the position feedback difference between the two axes by the same gain as the position control, the dependent axis is controlled using the corrected speed command, and the synchronous control is performed (for example, , See Patent Document 2). In addition, there is one that performs synchronous control based on a difference signal calculated by comparing speed deviation signals between multiple axes (for example, see Patent Document 3). Also, by adding the speed command for each axis and the speed feedforward amount, and dividing the value by the speed feedforward amount, the speed error rate is obtained, and the speed feedforward amount is corrected by the speed error rate. Some perform synchronous control (see, for example, Patent Document 4). In addition, there are some which perform compensation control by generating a compensation signal based on a speed command of each axis (for example, see Patent Document 5).

The technique of Patent Document 1 will be described. In FIG. 4, reference numeral 11 denotes a position control unit that performs position control based on a position command and position feedback. A speed control unit 12 performs speed control based on a speed command and speed feedback which are outputs from the 11 position control unit. A current control unit 13 performs current control based on a torque command that is an output of the 12-speed control unit. Similarly, reference numeral 23 denotes a current control unit that performs current control on the second axis based on a torque command that is an output of the 12-speed control unit. A speed average calculating unit 51 averages the first axis speed feedback and the second axis speed feedback to calculate an average speed. A damping compensator 52 obtains a speed difference between the first-axis speed feedback and the second-axis speed feedback, and multiplies the damping coefficient to obtain a correction torque.
In FIG. 4, position control and speed control are performed only on the first axis, and current control is controlled independently. Speed control is performed using the average speed of the first and second axes, and synchronous control is performed by obtaining a correction torque based on the speed difference between the two axes and correcting the torque of both motors. Yes.

The technique of Patent Document 2 will be described. In FIG. 5, reference numeral 22 denotes a speed control unit for the second axis, which performs speed control based on speed feedback for the second axis. The same parts as those in FIG. 4 described above are denoted by the same reference numerals and description thereof is omitted. A position correction gain 53 is obtained by multiplying the position feedback difference between the two axes by the same gain as in position control and outputting a position correction value.
In FIG. 5, the position control is performed only on the first axis, and the speed control and the current control are controlled independently. Then, a position correction value is obtained by multiplying the position feedback difference between the two axes by the same gain as the position control, and the second axis speed control is performed using the corrected speed command, thereby performing the synchronous control.

The technique of Patent Document 3 will be described. In FIG. 6, 54 and 55 are feedforward controllers, which calculate the feedforward amount of each axis and perform feedforward control. A synchronization controller 56 performs synchronization control based on a difference signal calculated by comparing speed deviation signals between two axes.
In FIG. 6, speed control and current control are controlled independently, and feedforward control is also controlled independently. And synchronous control is performed based on the difference signal calculated by comparing the speed deviation signals between the two axes.

The technique of Patent Document 4 will be described. In FIG. 7, reference numerals 57 and 59 denote speed feedforward amount calculation units, which calculate the speed feedforward amount of each axis and perform feedforward control. Reference numerals 58 and 60 denote speed control error rate calculation units, which calculate the speed error rate of each axis by adding the speed command and speed feedforward amount of each axis and dividing the value by the speed feedforward amount. .
In FIG. 7, the position control, speed control, current control and feedforward control are controlled independently. Then, in each axis, the speed error rate is obtained by adding the speed command and the speed feedforward amount and dividing the value by the speed feedforward amount, and the speed feedforward amount is corrected by the speed error rate. Synchronous control is being performed.

The technique of Patent Document 5 will be described. In FIG. 8, reference numeral 61 denotes a twin axis misalignment compensator, which creates a compensation signal according to a speed command for each axis. A speed loop gain adjuster 62 adjusts the speed loop gains of the first and second axes by the position feedback of the third axis.
In FIG. 8, the position control, speed control, and current control are controlled independently for all three axes. Then, a compensation signal is created according to the speed command of each axis, and the first and second axis synchronous control is controlled by adjusting the speed loop gains of the first and second axes according to the position of the third axis. Is going.
JP-A-8-16246 (see FIG. 1) Japanese Patent Laid-Open No. 11-305839 (see FIG. 2) Japanese Patent No. 3200907 (see FIG. 2) Japanese Patent No. 2854425 (see FIG. 1) Japanese Patent Laid-Open No. 5-40528 (see FIG. 1)

  In the conventional synchronous control device shown in FIGS. 4 and 5, position control is performed only on the first axis in both devices, and position control is not performed on the second axis. Therefore, when a disturbance is applied to the second axis, there is a problem that the position between the two axes is shifted. Further, since the conventional synchronous control device of FIG. 5 has only the second axis to be corrected, when the first axis vibrates due to disturbance or the like, the second axis also vibrates accordingly. There was also. In addition, the conventional synchronous control device of FIG. 7 performs synchronous control by reducing each speed error, but since each is controlled independently, there is a problem that the correction does not work once the position is shifted. There was also. In addition, the conventional synchronous control device of FIGS. 6 and 8 can synchronize the speed feedback because the correction signal is generated from the speed information, but the magnitude of the friction is greatly different between the two axes. There was a problem that the position feedback could not be synchronized. Further, the conventional synchronization control device of FIG. 7 has a problem that it cannot be synchronized in a transient state.

  The present invention has been made in view of such a problem, and when a disturbance is applied to either the first axis or the second axis, or when the magnitude of friction is greatly different between the two axes. However, it is an object of the present invention to provide a synchronous control device that can synchronize two axes and can synchronize not only speed feedback but also position feedback in a steady state and a transient state.

  In order to solve the above problem, the present invention is configured as follows.

The present invention synchronously drives one axis with a plurality of motors, and generates a feedforward signal for each axis based on a position command in a synchronous control apparatus having position control means by position feedback for each axis. A feedforward control unit for each axis, a synchronization error calculation unit for obtaining a synchronization error from a difference in position feedback between the two axes, a position correction signal calculation unit for obtaining a position correction signal from the obtained synchronization error, and each axis A feedforward correction signal calculating unit for obtaining a feedforward correction signal for each axis from the feedforward signal and the position correction signal, and an adding unit for each axis for adding the feedforward correction signal to the speed command for each axis. Is.
The position correction calculation unit filters the synchronization error with a low-pass filter and adjusts the gain of the position correction signal calculation unit so that the synchronization error is minimized.
Further, the position correction signal obtained by the position correction signal calculation unit is added to the feedforward signal of the first axis to obtain a feedforward correction signal, and the feedforward signal of the second axis is obtained. Subtracts to obtain a feedforward correction signal.

2. The synchronization control device according to claim 1, wherein a differential operation unit for differentiating the synchronization error obtained by the synchronization error operation unit, and a speed for obtaining a speed correction signal from the differentiated synchronization error output by the differentiation operation unit. A correction signal calculation unit, a correction signal calculation unit for obtaining a correction signal by adding the position correction signal output from the position correction signal calculation unit, and a speed correction signal output from the speed correction signal calculation unit, and each axis A feedforward correction signal calculation unit for obtaining a feedforward correction signal for each axis from each feedforward signal and the correction signal.
5. The synchronization control device according to claim 4, wherein the speed correction signal calculation unit filters the differentiated synchronization error with a low-pass filter and adjusts the gain of the speed correction signal calculation unit so that the synchronization error is minimized. It is characterized by doing.
5. The synchronous control device according to claim 4, wherein the correction signal obtained by the correction signal calculation unit is added to the feedforward signal of the first axis to obtain a feedforward correction signal, and the second axis The feedforward correction signal is obtained by subtracting the feedforward signal of the eye.

According to the present invention, since position control is performed independently, the position does not shift in a steady state. Further, since the feedforward signal for each axis is generated from the same position command, the speed can be easily synchronized even in a transient state. In addition, even if a deviation occurs between two axes due to disturbance or friction, a synchronization error is obtained from the difference in position feedback between the two axes, and the feedforward signal of each axis is corrected. The synchronization error can be minimized. Further, even when a disturbance is applied to only one axis, the synchronization error is controlled to be minimized, so that there is an advantage that the disturbance is stronger than the case where the control is performed with only one axis.
In addition to the above effect, correction is performed using a correction signal obtained by differentiating the synchronization error, so that even when the speed between the two axes is shifted, the shift can be minimized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a control block diagram illustrating the configuration of the first embodiment of the present invention. The same parts as those in FIGS. 4, 5, 6, 7, and 8 described above are denoted by the same reference numerals and description thereof is omitted. In the figure, reference numerals 17 and 27 denote feedforward control units, which generate a feedforward signal by multiplying a change in position command by a feedforward gain. Reference numeral 41 denotes a synchronization error calculation unit that calculates a difference in position feedback between the two axes to obtain a synchronization error. Reference numeral 42 denotes a position correction signal calculation unit, which calculates a position correction signal by multiplying the obtained synchronization error by a gain. Further, the 42-position correction calculation unit can perform a filtering process such as a low-pass filter on the input synchronization error as necessary. By adjusting this gain, it is possible to control so that the synchronization error is minimized. Reference numerals 18 and 28 determine the feedforward correction signal for each axis from the feedforward signal for each axis and the position correction signal obtained by the 42 position correction signal calculation unit. The position correction signal obtained by the 42 position correction signal calculation unit is added to the feedforward signal of the first axis to obtain a feedforward correction signal, and is subtracted from the feedforward signal of the second axis. Thus, a feedforward correction signal is obtained. This sign is because when the synchronization error is obtained, the direction of the first axis is set as the positive direction, so that a correction signal can be added in a direction to reduce the synchronization error between the two axes. Reference numerals 19 and 29 denote addition units for adding a feedforward correction signal to the speed command.

  The present invention is different from Patent Documents 1, 2, 3, 4, and 5 in that the position control, the speed control and the current control are controlled independently, and the feedforward signal of each axis is based on the position command. A feedforward control unit (17, 27) for generating a synchronization error, a synchronization error calculation unit (41) for obtaining a synchronization error from a difference in position feedback between two axes, and a position correction signal for obtaining a position correction signal from the obtained synchronization error A calculation unit (42), a feedforward correction signal calculation unit (18, 28) for obtaining a feedforward correction signal for each axis from the feedforward signal and position correction signal for each axis, and an addition for adding the feedforward correction signal to the speed command Part (19, 29).

  Since each axis performs position control independently, the position does not shift in a steady state. Even in a transient state, since feedforward control is performed by a feedforward signal created from the same position command, the identification error is minimized both in position and speed. In addition, even if a displacement occurs between the two axes due to disturbance or friction, the position correction signal calculation unit obtains a correction signal corresponding to the amount of displacement and reduces the displacement with respect to the feedforward signal. Since the correction is performed, the positional deviation is corrected immediately. And since correction is performed for each axis, even when only one axis vibrates due to a disturbance or the like, the problem that the second axis vibrates accordingly does not occur, but rather the vibration is suppressed. Since the correction works in the direction, there is also a merit that it is more resistant to disturbances than when control is performed with only one axis.

FIG. 3 shows the simulation result of the first embodiment of the present invention.
(A) is a response when the two axes are controlled independently without correction. The waveform on the left is a simulation result when the magnitude of friction differs greatly between the two axes, and is the response of position, torque, position deviation, and synchronization error, respectively. It can be seen that when the magnitude of friction differs between the two axes, a large synchronization error appears in the transient state. The waveform on the right is a simulation result when a disturbance is applied only to one axis and vibration is generated. Since the disturbance is applied only to one axis, the axis to which the disturbance is applied vibrates, but the other axis does not vibrate because no disturbance is applied.
(B) is the simulation result of the conventional synchronous control apparatus. Similarly, the waveform on the left side is a simulation result when the magnitude of friction is greatly different between the two axes, and the waveform on the right side is a simulation result when a disturbance is applied to only one axis and vibration is generated. In the conventional synchronous control device, if the friction between the two axes is different, the synchronization error tends to be somewhat small. However, if the disturbance is applied to only one axis and vibration is generated, the synchronization error is small. In addition, when looking at the positional deviation of each axis, the vibration is rather large.
(C) is a simulation result of the first embodiment of the present invention. Even when the magnitude of friction between the two axes is different, almost no synchronization error occurs. Even when a disturbance is applied to only one axis and the vibration is generated, the synchronization error is small and the vibration of each axis is reduced. You can see that

  FIG. 2 is a control block diagram for explaining the configuration of the second embodiment of the present invention. The same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted. 2 is different from FIG. 1 in that a differential calculation unit 43, 44 speed correction signal calculation unit, and correction signal calculation unit 45 are added. In the figure, reference numeral 43 denotes a differentiation calculation unit, which differentiates the synchronization error obtained in the 41 synchronization error calculation unit. Reference numeral 44 denotes a speed correction signal calculation unit, which obtains a speed correction signal by multiplying the differentiated synchronization error by a gain. In addition, the 44 speed correction calculation unit can perform filtering processing such as a low-pass filter on the differentiated synchronization error as necessary. By adjusting this gain, it is possible to control so that the speed synchronization error is minimized. Reference numeral 45 denotes a correction signal calculation unit which adds the position correction signal obtained by the 42 position correction signal calculation unit and the speed correction signal obtained by the 44 speed correction signal calculation unit to obtain a correction signal. Reference numerals 18 and 28 determine the feedforward correction signal for each axis from the feedforward signal for each axis and the correction signal obtained by the 45 correction signal calculation unit. The correction signal obtained by the 45 correction calculation unit is added to the feed-forward signal of the first axis to obtain a feed-forward correction signal, and is subtracted from the feed-forward signal of the second axis. Obtain the forward correction signal. This sign is because the direction of the first axis is set to the positive direction when the synchronization error is obtained, so that a correction signal can be applied in a direction to reduce the synchronization error between the two axes in both position and speed.

  The present invention is different from Patent Documents 1, 2, 3, 4, and 5 in that the position control, the speed control and the current control are controlled independently, and the feedforward signal of each axis is based on the position command. A feedforward control unit (17, 27) for generating a synchronization error, a synchronization error calculation unit (41) for obtaining a synchronization error from a difference in position feedback between two axes, and a position correction signal for obtaining a position correction signal from the obtained synchronization error A calculation unit (42), a differential calculation unit (43) for differentiating the obtained synchronization error, a speed correction signal calculation unit (44) for obtaining a speed correction signal from the differentiated synchronization error, a position correction signal and a speed correction A correction signal calculation unit (45) for adding signals to obtain a correction signal, and a feed forward correction for obtaining a feed forward correction signal for each axis from the feed forward signal and the correction signal for each axis. Signal calculating section (18, 28), adding section adding the feedforward correction signal to the speed command and the (19, 29), a portion with a.

  In the second embodiment, in addition to the operation of the first embodiment, the correction is also performed by the speed correction signal obtained by differentiating the synchronization error. Therefore, even when the speed between the two axes is shifted due to disturbance, friction, etc. Can be minimized.

  By controlling the position of each axis independently, the synchronization error in the steady state is minimized, and the feedforward control is performed with the feedforward signal created from the same position command, so that even in the transient state, the speed can be easily adjusted. Can be synchronized. In addition, even if a deviation occurs between two axes due to disturbance or friction, the synchronization error is obtained from the difference in position feedback between the two axes, and the feedforward signal of each axis is corrected to correct not only the speed but also the position. In this case, the synchronization error can be minimized. Furthermore, even when a disturbance is applied only to one axis, there is a merit that it is more resistant to disturbance compared to the case where control is performed with only one axis by controlling to minimize the synchronization error. The present invention can also be applied to a twin drive driving device that drives one table with two motors in an electronic component mounting apparatus or a liquid crystal manufacturing apparatus. The present invention is particularly useful for a semiconductor manufacturing apparatus, a stepper for driving an exposure apparatus, and a liquid crystal manufacturing apparatus that require ultra-precise positioning accuracy.

Control block diagram for explaining the configuration of the first embodiment of the present invention Control block diagram for explaining the configuration of the second embodiment of the present invention Simulation results of the first embodiment of the present invention Control block diagram of conventional synchronous control device Control block diagram of conventional synchronous control device Control block diagram of conventional synchronous control device Control block diagram of conventional synchronous control device Control block diagram of conventional synchronous control device

Explanation of symbols

11, 21, 31 Position controller 12, 22, 32 Speed controller 13, 23, 33 Current controller 14, 24, 34 Motor 15, 25, 35 Encoder 16, 26, 36 Speed calculator 17, 27 Feed forward control Units 18 and 28 Feed forward correction signal calculation units 19 and 29 Addition unit 41 Synchronization error calculation unit 42 Position correction signal calculation unit 43 Differentiation calculation unit 44 Speed correction signal calculation unit 45 Correction signal calculation unit 51 Speed average calculation unit 52 Damping compensator 53 Position correction gains 54 and 55 Feed forward controller 56 Synchronization controller 57 and 59 Speed feed forward amount calculation unit 58 and 60 Speed control error rate calculation unit 61 Twin axis position deviation compensator 62 Speed loop gain adjuster

Claims (6)

In a synchronous control device that synchronously drives one axis with a plurality of motors and includes position control means by position feedback for each axis,
A feedforward control unit for each axis that creates a feedforward signal for each axis based on a position command;
A synchronization error calculation unit for obtaining a synchronization error from the difference in position feedback between the two axes;
A position correction signal calculation unit for obtaining a position correction signal from the obtained synchronization error;
A feedforward correction signal calculation unit for obtaining a feedforward correction signal of each axis from the feedforward signal and position correction signal of each axis;
An adder for each axis that adds a feedforward correction signal to the speed command for each axis;
A synchronization control device comprising:   2. The synchronization control apparatus according to claim 1, wherein the position correction calculation unit filters the synchronization error with a low-pass filter and adjusts the gain of the position correction signal calculation unit so that the synchronization error is minimized. .   The position correction signal obtained by the position correction signal calculation unit is added to the feedforward signal on the first axis to obtain a feedforward correction signal, and subtracted from the feedforward signal on the second axis. The synchronous control apparatus according to claim 1, wherein a feedforward correction signal is obtained. A differential operation unit for differentiating the synchronization error obtained by the synchronization error calculation unit;
A speed correction signal calculation unit for obtaining a speed correction signal from the differentiated synchronization error output by the differential calculation unit;
A correction signal calculation unit for obtaining a correction signal by adding the position correction signal output from the position correction signal calculation unit and a speed correction signal output from the speed correction signal calculation unit;
The synchronous control apparatus according to claim 1, further comprising: a feedforward correction signal calculation unit that obtains a feedforward correction signal for each axis from the feedforward signal for each axis and the correction signal.   5. The synchronization according to claim 4, wherein the speed correction signal calculation unit filters the differentiated synchronization error with a low-pass filter and adjusts the gain of the speed correction signal calculation unit so that the synchronization error is minimized. Control device.   The correction signal obtained by the correction signal calculation unit is added to the feedforward signal on the first axis to obtain a feedforward correction signal, and subtracted from the feedforward signal on the second axis. 5. The synchronous control device according to claim 4, wherein a feedforward correction signal is obtained.

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