Motor control device and motor control method

Abstract

To provide a motor control device and a motor control method capable of dealing with unspecified oscillations while maintaining control responsiveness.SOLUTION: A control device 10 of a linear motor 1 that drives a stage 11 includes an oscillation detection unit 41 that determines the change over time in the position deviation of the stage 11 over a predetermined period of time and detects the presence or absence of oscillation of the stage 11 using the change over time, and controls the linear motor 1 on the basis of the detection result of the oscillation detection unit 41.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a motor control device and a motor control method. [Background technology]

[0002] A motor includes a stator and a mover, and is configured to move the mover relative to the stator by magnetically generating a thrust between the stator and the mover. A typical example of a motor is a linear motor, which is configured to have a mover in which multiple permanent magnets are arranged so that their magnetism alternates, and a stator in which a coil is wound around each of multiple magnetic pole teeth, and is arranged in correspondence with each other at a predetermined distance, and in which an AC current is passed through the coil of the stator to generate a thrust by the attraction / repulsion force between the permanent magnets and the stator, thereby linearly moving the mover relative to the stator.

[0003] For example, Patent Document 1 discloses that a linear motor for driving a stage is equipped with a disturbance compensator that uses a disturbance observer, and compensates for disturbance factors such as fluctuations in guiding friction of a linear guide mechanism that fluctuates depending on the position of the stage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-218497 A Summary of the Invention [Problem to be solved by the invention]

[0005] Since the stage has multiple moving axes and a complex configuration with various parts mounted on it, it has multiple natural frequencies, and natural vibrations (oscillations) can occur at specific or unspecific positions during movement. Since such oscillations deteriorate the responsiveness of the stage control, measures are taken such as performing PID (Proportional-Integral-Differential) control with low gain, or using a notch filter for the natural vibration at the specific position.

[0006] However, when PID control is performed in a low gain state, a problem occurs in which the control response is poor, and when a notch filter is used, a problem occurs in which it is not possible to respond when the natural frequency fluctuates or when natural vibration occurs at an unknown, unspecified position. Such problems are not considered in Patent Document 1, and therefore cannot be solved.

[0007] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a motor control device and a motor control method that can handle unspecified oscillations while maintaining control responsiveness. [Means for solving the problem]

[0008] The motor control device according to the present disclosure is a control device for a motor that drives a stage, and is equipped with a detection unit that determines the change in position deviation of the stage over a predetermined period of time and detects whether or not the stage is oscillating using the change over time, and controls the motor based on the detection result of the detection unit.

[0009] In the present disclosure, the detection unit detects whether or not the stage is oscillating by using the change in the position deviation of the stage over time, and the motor is controlled based on the detection results, so that it is possible to respond to unspecified oscillations while maintaining control responsiveness.

[0010] The motor control device according to the present disclosure controls a PID of the motor in response to the detection result of the detection unit. The motor drive system includes a gain adjustment unit that adjusts a gain related to control, and a control unit that controls a current to be supplied to the motor based on a result of the gain adjustment.

[0011] In the present disclosure, the gain adjustment unit adjusts the gain related to PID control of the motor in accordance with the detection result of the detection unit, and the control unit controls the current to be supplied to the motor based on the result of the gain adjustment, thereby controlling the motor.

[0012] In the motor control device of the present disclosure, the gain adjustment unit sets the gain to a first value when there is no oscillation of the stage, and sets the gain to a second value lower than the first value when there is oscillation of the stage.

[0013] In the present disclosure, the gain adjustment unit sets the gain to a first value when there is no stage oscillation, reduces the gain to a second value lower than the first value when there is stage oscillation, and then returns the gain to the original first value when the stage oscillation disappears again.

[0014] In the motor control device according to the present disclosure, the gain adjustment unit adjusts the gain at a predetermined rate of change (amount of gain change / second).

[0015] In the present disclosure, when the gain adjustment unit adjusts the gain, the adjustment is not performed instantaneously, but at a predetermined rate of change (amount of gain change / second) that is set in advance.

[0016] The motor control device according to the present disclosure includes a disturbance observer control system that determines an estimated value of a disturbance used for disturbance correction.

[0017] In the present disclosure, in addition to the PID control using the adjusted gain, disturbance observer control is performed to subtract an estimated value of the disturbance.

[0018] The motor control method according to the present disclosure is a method for controlling a motor that drives a stage, which determines a change in position deviation of the stage over a predetermined period of time, detects whether or not the stage is oscillating using the change in time, and controls the motor based on the detection results.

[0019] In the present disclosure, the presence or absence of stage oscillation is detected using the change in the stage position deviation over time, and the motor is controlled based on the detection results, thereby making it possible to respond to unspecified oscillations while maintaining control responsiveness. Effect of the Invention

[0020] According to the present disclosure, it is possible to provide a motor control device and a motor control method that can handle unspecified oscillations while maintaining control responsiveness. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view showing a configuration of a linear motor. [Diagram 2] FIG. 2 is a side view showing the configuration of a linear motor. [Diagram 3] 1 is a block diagram showing a configuration of an embodiment of a control device according to a first embodiment. [Figure 4] 13 is a graph showing a spectrum peak, a position error fluctuation, and a speed fluctuation when PID control is performed in a low gain state as a measure against oscillation of the stage. [Diagram 5] 11 is a graph showing a spectrum peak, a position error fluctuation, and a speed fluctuation when PID control is performed in a high gain state. [Figure 6] 4 is a flowchart illustrating gain adjustment and PID control in the control device according to the first embodiment. [Figure 7] 5 is a graph showing a spectrum peak, a position error fluctuation, and a speed fluctuation in the control device according to the first embodiment. [Figure 8] FIG. 11 is a block diagram showing a configuration of an embodiment of a control device according to a second embodiment. [Figure 9] FIG. 2 is a block diagram showing an internal configuration of a disturbance observer of the control device. [Figure 10] 10 is a graph showing a spectrum peak, a position error fluctuation, and a speed fluctuation in the control device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (Embodiment 1) The present invention will be described in detail with reference to the drawings showing the embodiments. In the following, the present invention will be described as being applied to a positioning stage using a linear motor as an example of a motor. For example, a substrate on which a semiconductor die is mounted is vacuum-attached onto the stage.

[0023] 1 and 2 are a perspective view and a side view showing the configuration of a linear motor 1. The linear motor 1 has a mover 2 and a stator 3 that face each other at a predetermined distance. For example, the mover 2 is mounted on a stage 11 (see FIG. 3), and the stator 3 is mounted on a stand (not shown).

[0024] The mover 2 is configured by supporting and fixing, for example, 14 rectangular permanent magnets 21 at an equal pitch to a thin plate-like back yoke 22 and juxtaposing them in the moving direction (left-right direction in FIG. 2). Each permanent magnet 21 is magnetized in the thickness direction (up-down direction in FIG. 2), and the magnetization directions of adjacent permanent magnets 21, 21 are opposite to each other. That is, permanent magnets 21 magnetized in the direction from the mover 2 side toward the stator 3 side (top-down direction in FIG. 2) and permanent magnets 21 magnetized in the direction from the stator 3 side toward the mover 2 side (bottom-up direction in FIG. 2) are arranged alternately.

[0025] On the other hand, the stator 3 is configured by integrally providing, for example, 30 rectangular magnetic pole teeth 32 at equal pitches in the moving direction on a thin plate-like core 31, and winding coils 33 around each of the magnetic pole teeth 32. U, V, and W in Fig. 2 respectively indicate the U-phase, V-phase, and W-phase of a three-phase AC power supply, and three pairs of forward and reverse two slots are formed as one set in order to perform three-phase parallel current. The linear motor 1 has a seven-pole, six-slot configuration having seven permanent magnets 21, six magnetic pole teeth 32, and coils 33 as a basic unit.

[0026] When a three-phase AC current is applied to the coil 33 of the stator 3 to generate a magnetic field in the magnetic pole teeth 32, the permanent magnets 21 of the mover 2 are sequentially magnetically attracted and repelled by this magnetic field, generating a thrust in the mover 2, causing the mover 2 to perform linear motion relative to the stator 3. This causes the stage 11 to move.

[0027] 3 is a block diagram showing a configuration of an embodiment of the control device 10 according to the embodiment 1. The control device 10 appropriately controls the linear motor 1 that drives the stage 11. The control device 10 includes a position command unit 80, a controller 50 (a control unit), a gain adjuster 40, an oscillation detector 41 (a detector), and a first subtractor 81, and performs PID control on the linear motor 1.

[0028] The input terminal of the linear motor 1 to be controlled is connected to the output terminal of the controller 50, and the output terminal of the linear motor 1 is connected to a subtraction input terminal of a first subtractor 81. The input terminal of the controller 50 and the input terminal of the oscillation detection unit 41 are connected to the output terminal of the first subtractor 81. The addition input terminal of the first subtractor 81 is connected to the output terminal of the position command unit 80. The output terminal of the oscillation detection unit 41 is connected to the input terminal of the gain adjustment unit 40, and the output terminal of the gain adjustment unit 40 is connected to the input terminal of the controller 50.

[0029] An input command u1 (position command) is input from a position command unit 80 to an addition input terminal of the first subtractor 81, and a drive current u is input to the linear motor 1. In practice, the drive current u is output from a servo amplifier (not shown) to the linear motor 1 in response to a current command u2 input from the controller 50.

[0030] In addition, the position of the stage 11 (the mover 2) is detected by a position detection unit (not shown) provided on the stage 11, and position information x representing the position of the stage 11 is output to the subtraction input terminal of the first subtractor 81 and to the outside.

[0031] The position command unit 80 outputs an input command u1 from an output terminal in accordance with a predetermined program in order to control the position of the stage 11. The position command unit 80 is connected to the oscillation detection unit 41 and the controller 50 via a first subtractor 81.

[0032] The first subtractor 81 calculates the difference (position deviation) between the input command u1 input from the position command unit 80 to the addition input terminal and the position information x input to the subtraction input terminal, and a position deviation signal representing this position deviation is input to the oscillation detection unit 41 and the control controller 50.

[0033] The oscillation detection unit 41 detects whether oscillation of the stage 11 has occurred based on the position deviation, and if oscillation of the stage 11 is detected by the oscillation detection unit 41, the gain adjustment unit 40 adjusts the gain used for PID control of the stage 11 (movable element 2), and the control controller 50 performs PID control of the stage 11 using the adjusted gain.

[0034] The oscillation detection unit 41 detects the presence or absence of oscillation of the stage 11 using a change over time in the position deviation of the stage 11 (the mover 2) during a predetermined period. Specifically, the oscillation detection unit 41 detects whether or not oscillation of the stage 11 has occurred using a spectrum calculated from the position deviation of the stage 11 accumulated during a predetermined period. Here, the predetermined period is, for example, several×10 -1 sec~number×10 -3It is in seconds. The oscillation detection unit 41 collects and accumulates the position deviation data for a certain period of time, and obtains a spectral peak based on the position deviation data for each predetermined control period longer than the certain period of time and calculates the spectral peak value (see FIG. 7A).

[0035] Specifically, the oscillation detection unit 41 accumulates the position deviation data for N pieces in a memory (not shown), and performs discrete Fourier transform on the N pieces of data for each servo cycle (f). In the discrete Fourier transform, the spectral peaks of all "N - 2" points at the frequency points (n × frequency step) where 0 < n < N - 1 are calculated. The maximum spectral peak value is calculated from among the spectral peak values of each of these frequency points. Here, the frequency step (s) is "(1 / N) × f", and the frequency points are "1 × s, 2 × s, 3 × s, …, (N - 2) × s".

[0036] As a specific example, when N is "500" and f is "12 (kHz)", the frequency step (s) is "24 (Hz)", and the frequency points are "24, 48, 72, …, 11952". The larger the number of data (N), the finer the spectral values can be detected from lower frequencies, and the performance can be improved. Also, increasing the number of N and calculating the spectral peak values of finer frequencies from lower frequencies leads to countermeasures against false detection of oscillation described later.

[0037] When the maximum spectral peak value is calculated, the oscillation detection unit 41 compares the threshold value stored in advance with the maximum spectral peak value, and determines whether oscillation in stage 11 has occurred. When the maximum spectral peak value is less than or equal to the threshold value, the oscillation detection unit 41 determines that oscillation in stage 11 has not occurred. Also, when the maximum spectral peak value is higher than the threshold value, the oscillation detection unit 41 determines that oscillation in stage 11 has occurred. The oscillation detection unit 41 notifies the gain adjustment unit 40 of the detection result for each control period.

[0038] The gain adjustment unit 40 adjusts the gain according to the detection result of the oscillation detection unit 41. That is, according to the contents of the notification from the oscillation detection unit 41, the gain adjustment unit 40 adjusts the gain related to the PID control of the stage 11 (the mover 2).

[0039] The gain adjustment by the gain adjustment unit 40 is not performed instantaneously, but at a predetermined rate of change (gain change amount / sec). If the gain adjustment is performed instantaneously, this is undesirable because it becomes a disturbance and may cause a position deviation of the stage 11. For example, the rate of change is 1 / sec to 3 / sec.

[0040] Specifically, when a notification that there was no oscillation is received, the gain adjustment unit 40 sets the gain to a predefined first value, and when a notification that there was oscillation is received, the gain adjustment unit 40 reduces the gain to a predefined second value lower than the first value. After reducing the gain to the second value, when a notification that there was no oscillation is received again, the gain adjustment unit 40 returns the gain to the first value. When a gain adjustment is performed, the gain adjustment unit 40 transmits the result of such adjustment to the controller 50.

[0041] Here, the gains related to the PID control include a proportional (P) gain, an integral (I) gain, and a differential (D) gain. The gain adjustment unit 40 may adjust these gains simultaneously, or may adjust each of them at different timings. The gain adjustment unit 40 may adjust all of these gains, or may selectively adjust some of the gains as necessary.

[0042] The threshold value can be set by the user as necessary. The smaller the threshold value is set, the faster oscillations can be detected and the more likely it is that large oscillations will be prevented from occurring.

[0043] The control controller 50 performs PID control based on the result of gain adjustment input from the gain adjustment unit 40 so as to match the input command u1 with the position information x. The control controller 50 performs proportional (P), integral (I) and differential (D) processing from the position deviation between the input command u1 and the position information x using the gain adjusted by the gain adjustment unit 40, and outputs a current command u2 for controlling the current to be supplied to the linear motor 1. In response to the current command u2 from the control controller 50, as described above, a predetermined processing is performed in the servo amplifier, and a drive current u is output to the linear motor 1.

[0044] Generally, a stage has multiple moving axes and has a complex configuration with various parts mounted thereon, including a Cableveyor (registered trademark). As a result, the stage has multiple natural frequencies, and natural vibrations (oscillations) can occur at specific or unspecific positions due to factors such as a change in the center of gravity position caused by movement. Such oscillations become disturbances, and as they deteriorate the responsiveness of the stage control, measures are required. Measures against such disturbances include performing PID control with low gain, or using a notch filter that can handle the natural vibrations at the specific positions.

[0045] However, when PID control is performed in a low gain state as a countermeasure against oscillation, the control response is poor.In addition, when a notch filter is used, although it can handle known natural vibrations, it cannot handle unspecified oscillations, such as when the natural frequency changes due to the effects of aging, or when natural vibrations occur at unknown, unspecified positions.

[0046] Figure 4 shows how PID control is performed in low gain mode to counter oscillation in stage 11. 4 is a graph showing a spectrum peak, a position deviation fluctuation, and a speed fluctuation in a case where the position deviation fluctuation is set to 0. FIG. 4A shows the spectrum peak, FIG. 4B shows the position deviation fluctuation, and FIG. 4C shows the speed fluctuation. For convenience of explanation, FIG. 4 shows only an example of a proportional gain as the gain, and does not show examples of a differential gain and an integral gain. Furthermore, the proportional gain is a constant value of 80%.

[0047] In Fig. 4A, the horizontal axis is time, the left vertical axis is the spectrum peak value, and the right vertical axis is the proportional gain. Also, in Fig. 4A, the solid line corresponds to the spectrum peak value, and the dashed line corresponds to the proportional gain. In Fig. 4B, the horizontal axis is time, the left vertical axis is position deviation, and the right vertical axis is command position. In Fig. 4B, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position. In Fig. 4C, the horizontal axis is time, the left vertical axis is speed, and the right vertical axis is command position. In Fig. 4C, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position.

[0048] As shown in Fig. 4, when PID control is performed in a low gain state as a countermeasure against oscillation, the fluctuations in the spectrum peak value and position deviation are small when the stage 11 is stopped (see Figs. 4A and 4B), and the stage 11 is stable because it does not vibrate. However, when the stage 11 is moving, the spectrum peak value is large (see Fig. 4A), and the speed fluctuations are large and convergence is slow (see Fig. 4C), so as described above, the control responsiveness is poor.

[0049] If PID control is performed in a high gain state in order to solve the problem of poor control response that occurs when PID control is performed in a low gain state, the control response will be improved, but the problem of oscillation of stage 11 will occur.

[0050] Fig. 5 is a graph showing a spectrum peak, a position deviation fluctuation, and a speed fluctuation when PID control is performed in a high gain state. Fig. 5A shows a spectrum peak, Fig. 5B shows a position deviation fluctuation, and Fig. 5C shows a speed fluctuation. For convenience of explanation, Fig. 5 shows only an example of a proportional gain as a gain, and does not show examples of a differential gain and an integral gain. Furthermore, the proportional gain is a constant value of 100%.

[0051] 5A, the horizontal axis is time, the left vertical axis is the spectrum peak value, and the right vertical axis is the proportional gain. In FIG. 5A, the solid line corresponds to the spectrum peak value, and the dashed line corresponds to the proportional gain. In Fig. 5B, the horizontal axis is time, the left vertical axis is position deviation, and the right vertical axis is command position. In Fig. 5B, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position. 5C, the horizontal axis is time, the left vertical axis is speed, and the right vertical axis is command position. In addition, in FIG. 5C, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position.

[0052] As shown in Fig. 5, when PID control is performed in the high gain state, the spectrum peak value is smaller when the stage 11 is moving than when the gain is low (see Fig. 5A), and the speed fluctuation is smaller and convergence is faster (see Fig. 5C), improving the control responsiveness. However, when the stage 11 stops, the spectrum peak value is larger, and oscillation of the stage 11 occurs (see Figs. 5A and 5B).

[0053] To address this problem, the control device 10 according to the first embodiment adjusts the gain used in the PID control of the stage 11 up or down depending on the detection result of the presence or absence of oscillation of the stage 11. This is solved by adjusting the gain and using the adjusted gain to PID control stage 11.

[0054] 6 is a flowchart illustrating gain adjustment and PID control in the control device 10 according to the embodiment 1. The following description will be given by way of example of a case in which the gain related to the PID control is adjusted to a first value or a second value smaller than the first value.

[0055] 6 is repeatedly performed for each control period upon start of the PID control in stage 11. When the PID control in stage 11 is started, the gain related to the PID control is a first value.

[0056] The oscillation detection unit 41 detects the presence or absence of oscillation of the stage 11, and determines whether or not oscillation of the stage 11 has occurred (step S101).

[0057] As described above, the oscillation detection unit 41 calculates the maximum spectral peak value from among the spectral peak values ​​based on the data on the position deviation of the stage 11, and compares the calculated maximum spectral peak value with a threshold value to determine whether or not oscillation of the stage 11 has occurred.

[0058] If the maximum spectrum peak value is greater than the threshold value, the oscillation detection unit 41 determines that oscillation has occurred in the stage 11 (step S101: YES), and sends a notice that oscillation has occurred in the stage 11 (hereinafter referred to as an occurrence notice) to the gain adjustment unit 40. When the occurrence notice is received from the oscillation detection unit 41, the gain adjustment unit 40 adjusts the gain related to the PID control of the stage 11 to a second value (step S102). This is an adjustment to lower the current gain at a preset rate of change (gain change amount / second) for each control period. That is, the second value of the gain after adjustment is "{gain before adjustment}-{gain change amount / second×control period (seconds)}". Furthermore, when the second value of the gain reaches a preset lower limit, it will not decrease below that value and will remain constant.

[0059] Also, if the maximum spectrum peak value is equal to or less than the threshold value, the oscillation detection unit 41 determines that there is no oscillation in the stage 11 (step S101: NO), and sends a notice to the effect that there is no oscillation in the stage 11 (hereinafter referred to as a non-occurrence notice) to the gain adjustment unit 40. When the non-occurrence notice is received from the oscillation detection unit 41, the gain adjustment unit 40 adjusts the gain related to the PID control of the stage 11 to a first value (step S104). This is an adjustment to increase the current gain at a preset rate of change (gain change amount / second) for each control period. That is, the first value of gain after adjustment is "{gain before adjustment}+{gain change amount / second×control period (seconds)}". Also, when the first value of gain reaches a preset upper limit value, it does not increase any more and remains constant.

[0060] The control controller 50 performs PID control of the stage 11 (mover 2) based on the result of the gain adjustment input from the gain adjustment unit 40 (step S103). For example, as in step S102, when the gain adjustment unit 40 adjusts the gain to a second value in response to the occurrence notification, the control controller 50 performs PID control using the adjusted second value of the gain. Also, as in step S104, when the gain adjustment unit 40 adjusts the gain to a first value in response to the non-occurrence notification, the control controller 50 performs PID control using the adjusted first value of the gain.

[0061] As described above, in order to solve the above problem, the control device 10 according to the first embodiment performs gain adjustment to lower the gain related to the PID control when the occurrence of oscillation of the stage 11 is detected, and to raise the gain back to the original value when the occurrence of oscillation of the stage 11 is no longer detected. The control device 10 performs PID control on the stage 11. The effect of the gain adjustment in the control device 10 according to the first embodiment will be described below.

[0062] Fig. 7 is a graph showing a spectrum peak, a position deviation fluctuation, and a speed fluctuation in the control device 10 according to the first embodiment. Fig. 7A shows a spectrum peak, Fig. 7B shows a position deviation fluctuation, and Fig. 7C shows a speed fluctuation. For ease of explanation, Fig. 7 shows only an example of a proportional gain as a gain, and does not show examples of a differential gain and an integral gain. Furthermore, the proportional gain when no oscillation of the stage 11 occurs is 100%, which is given as an example of a high gain in Fig. 5.

[0063] In Fig. 7A, the horizontal axis is time, the left vertical axis is the spectrum peak value, and the right vertical axis is the proportional gain. In Fig. 7A, the solid line corresponds to the spectrum peak value, the dashed line corresponds to the proportional gain, and the dashed line corresponds to the threshold value. In the example of Fig. 7A, the threshold value is 0.0003. In Fig. 7B, the horizontal axis is time, the left vertical axis is position deviation, and the right vertical axis is command position. In Fig. 7B, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position. In Fig. 7C, the horizontal axis is time, the left vertical axis is speed, and the right vertical axis is command position. In Fig. 7C, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position.

[0064] 7A, in the control device 10 according to the first embodiment, the proportional gain is 100% (first value) before oscillation of the stage 11 is detected. Thereafter, when oscillation of the stage 11 is detected, the proportional gain is reduced to a lower value of 80% (second value), and when oscillation of the stage 11 is no longer detected, the proportional gain is returned to 100%. Such adjustment of increasing and decreasing the proportional gain is repeated according to the detection result of oscillation of the stage 11.

[0065] As a result, in the case of the control device 10 according to the first embodiment, when the stage 11 is stopped, the fluctuations in the spectrum peak value and the position deviation are smaller (see FIGS. 7A and 7B) than in the case of high gain in FIGS. 5A and 5B, and no oscillation occurs in the stage 11. That is, in the control device 10 according to the first embodiment, the gain in the PID control is adjusted up or down depending on the presence or absence of oscillation, thereby making it possible to suppress oscillation when the stage 11 is stopped. Therefore, the control device 10 according to the first embodiment can improve the control responsiveness and suppress the oscillation of the stage 11. Moreover, since the control device 10 according to the first embodiment does not employ a notch filter, it can also handle unspecified oscillations.

[0066] In addition, in the control device 10 of embodiment 1, when vibrations of the stage 11 that occur during movement are detected as oscillations (misdetected), the gain adjustment unit 40 reduces the gain, which may result in reduced control responsiveness and large speed fluctuations, resulting in slow convergence. However, this can be improved by increasing the threshold value used to detect oscillations of the stage 11.

[0067] In the above, a description has been given of obtaining a spectrum peak based on data on position deviation, and then comparing the spectrum peak value with a pre-stored threshold value to determine whether or not oscillation of the stage 11 has occurred, but the present invention is not limited to this. For example, a spectrum peak may be obtained based on data on speed deviation.

[0068] (Embodiment 2) 8 is a block diagram showing a configuration of a control device 10 according to the second embodiment. The control device 10 includes a position command unit 80, a controller 50, a gain adjuster 40, an oscillation detector 41, and a first subtractor 81, as in the first embodiment. The control device 10 according to the second embodiment further includes a disturbance observer 61, a differentiator 62, and a second subtractor 71. The disturbance observer 61 and the differentiator 62 configure a disturbance observer control system 60.

[0069] The input end of the linear motor 1 is connected to the output terminal of the second subtractor 71. The output end of the linear motor 1 is connected to the input end of the differentiator 62 and the subtraction input terminal of the first subtractor 81. The output end of the differentiator 62 is connected to the input end of the disturbance observer 61, and the output end of the disturbance observer 61 is connected to the subtraction input terminal of the second subtractor 71. The output end of the control controller 50 is connected to the addition input terminal of the second subtractor 71. The input end of the control controller 50 and the input end of the oscillation detection unit 41 are connected to the output terminal of the first subtractor 81. The addition input terminal of the first subtractor 81 is connected to the output end of the position command unit 80. The output end of the oscillation detection unit 41 is connected to the input end of the gain adjustment unit 40, and the output end of the gain adjustment unit 40 is connected to the input end of the control controller 50.

[0070] An input command u1 (position command) is input from the position command unit 80 to an addition input terminal of the first subtractor 81, and a current command u2 is input from the controller 50 to an addition input terminal of the second subtractor 71. In addition, a control output ^d (estimated value of disturbance) is input from the disturbance observer 61 to a subtraction input terminal of the second subtractor 71. Note that the symbol "^" represents an estimated value.

[0071] Furthermore, a driving current u is input to the linear motor 1, and position information x representing the position of the stage 11 is output to the subtraction input terminal of the first subtractor 81, the differentiator 62, and to the outside.

[0072] The position command unit 80, the first subtractor 81, the oscillation detection unit 41, the gain adjustment unit 40, and the controller 50 have already been described in the first embodiment, and detailed description thereof will be omitted.

[0073] The current command u2 from the controller 50 is output to the second subtractor 71 and the disturbance observer 61. That is, the current command u2 obtained using the gain adjusted by the gain adjustment unit 40 is input to the addition input terminal of the second subtractor 71 and the disturbance observer 61. The disturbance estimate value ^d is input to the subtraction input terminal of the second subtractor 71 from the disturbance observer 61. The second subtractor 71 obtains the difference between the current command u2 and the disturbance estimate value ^d and outputs it to the linear motor 1.

[0074] FIG. 9 is a block diagram showing the internal configuration of the disturbance observer 61 of the control device 10. As shown in FIG. The disturbance observer 61 has a stationary Kalman filter 100. The stationary Kalman filter 100 is a type of infinite impulse response filter used to estimate or control the state of a dynamic system using actual measurements containing errors. The stationary Kalman filter 100 is widely used to estimate quantities that change over time (e.g., the position and speed of an object) from actual measurements containing discrete errors.

[0075] The disturbance observer 61 has a first parameter section 86, a second parameter section 87, a third parameter section 88, a fourth parameter section 89, a fifth parameter section 90, a first adder 91, a second adder 92, a subtractor 93, a first integrator 94, and a second integrator 95. Among these components, the first parameter section 86, the second parameter section 87, the third parameter section 88, the fourth parameter section 89, the first adder 91, the second adder 92, the subtractor 93, and the first integrator 94 configure a stationary Kalman filter 100.

[0076] An input terminal of the second parameter section 87 is connected to an output terminal of the controller 50, and an output terminal of the second parameter section 87 is connected to one of the addition input terminals of the first adder 91. An input terminal of the first integrator 94 is connected to the output terminal of the first adder 91, and an output terminal of the first integrator 94 is connected to the input terminal of the first parameter section 86 and the input terminal of the third parameter section 88. The output terminal of the third parameter section 88 is connected to the subtraction input terminal of the subtractor 93. The addition input terminal of the subtractor 93 is connected to the output terminal of the differentiator 62. The output terminal of the subtractor 93 is connected to the input terminal of the fourth parameter section 89 and the input terminal of the fifth parameter section 90. The output terminal of the first parameter section 86 is connected to one of the addition input terminals of the second adder 92, and the output terminal of the fourth parameter section 89 is connected to the other addition input terminal of the second adder 92. The output terminal of the second adder 92 is connected to the other addition input terminal of the first adder 91. The output terminal of the fifth parameter section 90 is connected to the input terminal of the second integrator 95, and the output terminal of the second integrator 95 is connected to the subtraction input terminal of the second subtractor 71.

[0077] A first parameter section 86, a second parameter section 87, and a third parameter section 88 respectively store state variable parameters A, B, and C of the model (input: current, output: speed). These parameters A, B, and C are derived according to a MATLAB (registered trademark) program.

[0078] The fourth parameter unit 89 calculates the state estimation parameters L xThe fifth parameter section 90 stores the disturbance estimation parameter L of the linear motor 1. d Parameter L x is the model gain, which specifies the sensitivity to the error that occurs between the waveform of the compared model and the waveform of the actual device. If you want to correct even a small error, this parameter L x Set the parameter L to a large value. d Also, parameter L x Similarly, it is a model gain for defining the sensitivity in the correction.

[0079] In actual implementation, it is preferable to use discretized values ​​for each of these parameters.

[0080] An estimate of the velocity waveform when a current command u2 is input from the controller 50 to the model (a velocity waveform when there is no influence of disturbance) is calculated. This calculated velocity waveform of the model is compared with the actual velocity waveform of the linear motor 1 obtained by differentiating the position information x by the differentiator 62, and the difference is calculated by the subtractor 93. In this way, the motion of the dynamic system (control target) is estimated using the estimate from the model, and the parameter L x Since a fixed value is used as the model gain, the filter takes the form of a stationary Kalman filter.

[0081] The difference (error) obtained by the subtractor 93 is used to determine an estimated disturbance value ^d, and the determined estimated disturbance value ^d is subtracted from the current command u2 by the second subtractor 71 to reduce the disturbance. In this way, the disturbance observer control system 60 performs disturbance observer control against disturbances during operation of the linear motor 1.

[0082] As described above, the second subtractor 71 receives the current command u2 obtained using the gain adjusted by the gain adjuster 40 at its addition input terminal, and receives the disturbance estimate ^d from the disturbance observer 61 at its subtraction input terminal. The second subtractor 71 obtains and outputs the difference between the current command u2 and the disturbance estimate ^d. Depending on the difference from the second subtractor 71, as described above, a predetermined process is performed in the servo amplifier, and the drive current u is output to the linear motor 1.

[0083] As described above, the control device 10 according to the second embodiment combines control for adjusting the gain based on the detection result of oscillation of the stage 11 with disturbance observer control by the disturbance observer control system 60. As a result, the control device 10 according to the second embodiment captures the vibration of the stage 11 that occurs during movement as a disturbance, and reduces the effects caused by the disturbance by the disturbance observer control.

[0084] 10A and 10B are graphs showing a spectrum peak, a position deviation fluctuation, and a speed fluctuation in the control device 10 according to the second embodiment. 10C shows deviation fluctuation, and FIG. 10C shows speed fluctuation. For convenience of explanation, FIG. 10 shows only an example of proportional gain as gain, and does not show examples of differential gain and integral gain. Furthermore, the proportional gain when no oscillation of stage 11 occurs is 100%, which is given as an example of high gain in FIG. 5.

[0085] In Fig. 10A, the horizontal axis is time, the left vertical axis is the spectrum peak value, and the right vertical axis is the proportional gain. In Fig. 10A, the solid line corresponds to the spectrum peak value, the dashed line corresponds to the proportional gain, and the dashed line corresponds to the threshold value. In the example of Fig. 10A, the threshold value is 0.0003. In Fig. 10B, the horizontal axis is time, the left vertical axis is position deviation, and the right vertical axis is command position. In Fig. 10B, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position. In Fig. 10C, the horizontal axis is time, the left vertical axis is speed, and the right vertical axis is command position. In Fig. 10C, the solid and dashed lines correspond to the two linear motors 1 provided on the stage 11, respectively, and the dashed and dotted lines correspond to the command position.

[0086] In the control device 10 of embodiment 2, as shown in FIG. 10A, before oscillation of stage 11 is detected, the proportional gain is 100%, and when oscillation of stage 11 is detected thereafter, the proportional gain is reduced to a lower value of 80%, and when oscillation of stage 11 is no longer detected, the proportional gain is returned to 100%.

[0087] As a result, in the case of the control device 10 of embodiment 2, when the stage 11 is stopped, the fluctuations in the spectrum peak value and position deviation are smaller than those in Figures 5A and 5B at high gain (see Figures 10A and 10B), the stage 11 does not vibrate, and oscillation of the stage 11 does not occur. Therefore, oscillation when the stage 11 is stopped can be suppressed despite the high gain.

[0088] Furthermore, in the control device 10 according to the second embodiment, the vibration of the stage 11 that occurs during movement is detected as a disturbance and disturbance observer control is performed. Therefore, even when the stage 11 moves, the speed fluctuation is smaller and convergence is faster than in the case of the high gain in FIG. 5C (see FIG. 10C).

[0089] Therefore, the control device 10 according to the second embodiment can further improve the control responsiveness and suppress the oscillation of the stage 11. Moreover, since the control device 10 according to the second embodiment does not employ a notch filter, it can also handle unspecified oscillations.

[0090] The disclosed embodiments should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0091] The matters described in each embodiment can be combined with each other. In addition, the independent claims and dependent claims described in the claims can be combined with each other in any and all combinations regardless of the citation format. Furthermore, the claims use a format in which a claim cites two or more other claims (multiple claim format), but this is not limited to this. The claims may also be written in a format in which a multiple claim cites at least one other multiple claim (multi-multi claim). [Explanation of symbols]

[0092] 1. Linear motor 10 Control device 11 Stage 40 Gain adjustment section 41 Oscillation detection unit (detection unit) 50 Controller (control unit) 60 Disturbance observer control system 61 Disturbance Observer

Claims

1. A control device for a motor that drives a stage, a detection unit that obtains a change in position deviation of the stage over a predetermined period of time and detects the presence or absence of oscillation of the stage using the change in position over time; A motor control device that controls the motor based on the detection result of the detection unit.

2. a gain adjustment unit that adjusts a gain related to a PID control of the motor in response to a detection result of the detection unit; The motor control device according to claim 1 , further comprising a control unit that performs control regarding a current to be supplied to the motor based on a result of the adjustment of the gain.

3. The gain adjustment unit is If there is no oscillation of the stage, the gain is set to a first value; 3. The motor control device according to claim 2, wherein, when oscillation of the stage occurs, the gain is set to a second value lower than the first value.

4. The motor control device according to claim 2 , wherein the gain adjustment unit adjusts the gain at a predetermined rate of change (amount of gain change / second).

5. 5. The motor control device according to claim 1, further comprising a disturbance observer control system for determining an estimated value of the disturbance used for disturbance correction.

6. A control method for controlling a motor that drives a stage, comprising the steps of: A change in position deviation of the stage over a predetermined period of time is obtained, and the presence or absence of oscillation of the stage is detected using the change in position over time; A motor control method for controlling the motor based on the result of the detection.

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