Motor control device and motor control method

Abstract

To achieve desired operating characteristics by greatly reducing the influence of the disturbance that occurs.SOLUTION: In a control device 10 for a linear motor 1 in which disturbance correction is performed, feedforward control of the linear motor 1 is performed using a disturbance-corrected current command u input to the linear motor 1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A motor has 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 has 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 configured to be spaced apart by a predetermined distance, and which generates a thrust by the attraction / repulsion force between the permanent magnets and the stator coils when an AC current is passed through the stator coils, 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 fluctuate depending on the position of the stage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-218497 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in addition to the friction mentioned above, other disturbance factors in driving the stage include the influence of tension in the current-carrying cable, vibration of the base on which the linear motor is held, cogging, etc., and so the so-called disturbance observer control using the disturbance observer described in Patent Document 1 alone is not sufficient to compensate for the disturbances that occur.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a motor control device and a motor control method that can significantly reduce the influence of disturbances that occur and achieve desired operating characteristics. [Means for solving the problem]

[0007] A motor control device according to the present invention is a motor control device that performs disturbance correction, and performs feedforward control of the motor using the disturbance-corrected input value that is input to the motor.

[0008] In the present invention, the disturbance-corrected input value input to the motor is used for feedforward control of the motor. Since the input value that has already been subjected to disturbance correction is used for feedforward control, the effect of suppressing disturbances in the motor can be improved.

[0009] The motor control device according to the present invention includes a memory unit that stores in advance the actual measured values of the input values, a first controller that performs the feedforward control using the actual measured values of the input values, a second controller that performs feedback control of the motor based on the difference between the position of an object driven by the motor and a position command value for the motor, and an adder that adds the output value of the first controller and the output value of the second controller and outputs the result to the motor.

[0010] In the present invention, the feedforward control using the actual measured value of the disturbance-corrected input value that is stored in advance and the feedback control based on the difference between the position of the object and the position command value are performed in combination, thereby improving the disturbance suppression effect of the motor.

[0011] The motor control device according to the present invention comprises a disturbance observer control system that determines an estimated value of the disturbance used for the disturbance correction, and a subtractor that determines the difference between the output value of the adder and the estimated value of the disturbance, and the subtractor outputs the difference to the motor.

[0012] In the present invention, in addition to the feedforward control and the feedback control, disturbance observer control is performed to subtract the estimated value of the disturbance, thereby further enhancing the effect of suppressing the disturbance of the motor.

[0013] In the motor control device according to the present invention, the disturbance observer control system has a stationary Kalman filter.

[0014] In the present invention, the disturbance observer control system uses the stationary Kalman filter for the disturbance observer control.

[0015] A motor control method according to the present invention is a motor control method for controlling a motor by performing disturbance correction, in which feedforward control of the motor is performed using the disturbance-corrected input value input to the motor.

[0016] In the present invention, the disturbance-corrected input value input to the motor is used for feedforward control of the motor. Since the input value that has already been subjected to disturbance correction is used for feedforward control, the effect of suppressing disturbances in the motor can be improved.

[0017] The motor control method according to the present invention stores the actual measured values of the input values in advance, performs the feedforward control using the actual measured values of the input values, performs feedback control of the motor based on the difference between the position of an object driven by the motor and a position command value for the motor, and outputs to the motor a sum obtained by adding together the value obtained by the feedforward control and the value obtained by the feedback control.

[0018] In the present invention, the feedforward control is performed using the actual measured value of the disturbance-corrected input value that is stored in advance, and the feedback control is also performed based on the difference between the position of the object and the position command value, thereby improving the disturbance suppression effect of the motor.

[0019] The motor control method according to the present invention determines an estimated value of the disturbance used for the disturbance correction, calculates the difference between the added value and the estimated value of the disturbance, and inputs the difference to the motor.

[0020] In the present invention, in addition to the feedforward control and the feedback control, disturbance observer control is performed to subtract the estimated value of the disturbance, thereby further enhancing the effect of suppressing the disturbance of the motor.

[0021] In the motor control method according to the present invention, the estimated value of the disturbance is determined using a stationary Kalman filter.

[0022] In the present invention, the disturbance observer control is performed using the stationary Kalman filter. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a motor control device and a motor control method that can significantly reduce the influence of disturbances that occur and achieve desired operating characteristics. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is a perspective view showing the configuration of a linear motor. [Figure 2] FIG. 2 is a side view showing the configuration of a linear motor. [Figure 3] 1 is a block diagram showing the configuration of an embodiment of a control device according to a first embodiment. [Figure 4] FIG. 4 is an illustrative diagram showing an example of a current command input to a linear motor. [Figure 5] FIG. 4 is an illustrative diagram showing an example of a feedforward value used in feedforward control. [Figure 6] FIG. 2 is a block diagram showing the internal configuration of a disturbance observer of the control device. [Figure 7] FIG. 4 is an illustrative diagram showing an example of a feedforward value used in feedforward control. DETAILED DESCRIPTION OF THE INVENTION

[0025] (Embodiment 1) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings showing embodiments thereof. In the following, a case will be described in which the present invention is applied to a positioning stage that employs a linear motor as an example of a motor.

[0026] 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 with a predetermined distance between them.

[0027] The mover 2 is configured by supporting and fixing, at equal intervals, for example, 14 rectangular permanent magnets 21 to a thin plate-like back yoke 22 and arranging them side by side in the direction of movement (left and right direction in FIG. 2). Each permanent magnet 21 is magnetized in the thickness direction (up and down direction in FIG. 2), and the magnetization directions of adjacent permanent magnets 21, 21 are opposite to each other. In other words, permanent magnets 21 magnetized in the direction from the mover 2 side toward the stator 3 side (top to bottom direction in FIG. 2) and permanent magnets 21 magnetized in the direction from the stator 3 side toward the mover 2 side (bottom to top direction in FIG. 2) are arranged alternately.

[0028] Meanwhile, the stator 3 is configured by integrally providing, for example, 30 rectangular magnetic pole teeth 32 at equal intervals in the moving direction on a thin plate-like core 31, and by winding a coil 33 around each magnetic pole tooth 32. U, V, and W in Fig. 2 respectively represent the U-phase, V-phase, and W-phase of a three-phase AC power supply, and three pairs of forward and reverse two-slot are formed as one set to perform three-phase parallel current conduction. The linear motor 1 has a basic unit of a seven-pole, six-slot configuration having seven permanent magnets 21, six magnetic pole teeth 32, and coils 33.

[0029] When a three-phase alternating current is passed through 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 move linearly relative to the stator 3.

[0030] A method and apparatus for reducing the influence of disturbances, including cogging, that inevitably occur in the linear motor 1 configured as described above will be described in detail below.

[0031] In the present invention, feedforward control using pre-stored feedforward values is combined with disturbance observer control for disturbances. That is, the influence of disturbances is roughly eliminated by the feedforward control, and the influence of disturbances that cannot be completely eliminated by the feedforward control is reduced by the disturbance observer control. Therefore, the influence of disturbances can be significantly reduced.

[0032] Taking the linear motor 1 as an example, disturbances include the effect of tension on the current-carrying cable (a phenomenon in which tension causes a difference in thrust between the forward and backward directions of the linear motor 1), friction, and vibration of the base that holds the linear motor 1. In the present invention, the effect of such disturbances on the linear motor 1 is suppressed by feedforward control and disturbance observer control.

[0033] 3 is a block diagram showing the configuration of one embodiment of the control device 10 according to embodiment 1. The control device 10 is attached to a stage 11 (object) and controls a linear motor 1 that drives the stage 11 as appropriate.

[0034] The control device 10 includes a position command unit 80, a control controller 50 (second controller), an FF corrector (feedforward corrector) 40 (first controller), a storage unit 41, a disturbance observer 61, a differentiator 62, a first subtractor 81, a second subtractor 71, and an adder 51. The disturbance observer 61 and the differentiator 62 configure a disturbance observer control system 60.

[0035] The input terminal of the linear motor 1 to be controlled is connected to the output terminal of the second subtractor 71. The output terminal of the linear motor 1 is connected to the input terminal of the differentiator 62 and the subtraction input terminal of the first subtractor 81. The output terminal of the differentiator 62 is connected to the input terminal of the disturbance observer 61, and the output terminal of the disturbance observer 61 is connected to the subtraction input terminal of the second subtractor 71. The output terminal of the adder 51 is connected to one of the addition input terminals of the adder 51, and the output terminal of the FF corrector 40 is connected to the other addition input terminal of the adder 51. The input terminal of the control controller 50 is connected to the output terminal of the first subtractor 81. The addition input terminal of the first subtractor 81 and the input terminal of the FF corrector 40 are connected to the output terminal of the position command unit 80. The FF corrector 40 is connected to a memory unit 41.

[0036] An input command u1 (position command value) is input to an addition input terminal of the first subtractor 81 from the position command unit 80, a current command u3 is input to one addition input terminal of the adder 51 from the control controller 50, and a current command u2 is input to the other addition input terminal of the adder 51 from the FF corrector 40. A current command u4 (addition value) is input to an addition input terminal of the second subtractor 71 from the adder 51, and a control output ^d (estimated value of the disturbance) is input to a subtraction input terminal of the second subtractor 71 from the disturbance observer 61. The symbol "^" represents an estimated value.

[0037] A current command u is input to the linear motor 1. The current command u is a current command output from the second subtractor 71 to the linear motor 1 side, but in reality, it is output to the linear motor 1 via a driver and a servo amplifier (not shown).

[0038] Fig. 4 is an illustrative diagram showing an example of a current command u input to the linear motor 1. In Fig. 4, the command speed is a speed corresponding to the input command u1. As can be seen from Fig. 4, the current command u changes over time and in accordance with the speed.

[0039] In addition, the position of the stage 11 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, the differentiator 62, and to the outside.

[0040] The position command unit 80 outputs an input command u1 to the linear motor 1 side in accordance with a predetermined program in order to control the position of the stage 11. The input command u1 is input to the FF corrector 40, and is also input to the controller 50 via a first subtractor 81.

[0041] The controller 50 performs feedback control on the input command u1. That is, the first subtractor 81 calculates the difference between the input command u1 input to the addition input terminal and the position information x input to the subtraction input terminal, and a difference signal representing this difference is input to the control controller 50. The control controller 50 applies proportional (P), integral (I), and differential (D) processing to this difference so as to match the input command u1 with the position information x, calculates a current command u3, and outputs it to the adder 51.

[0042] The FF corrector 40 also performs feedforward control on the input command u1, which will be explained in detail below. A storage unit 41 is connected to the FF corrector 40. The storage unit 41 stores a plurality of patterns of feedforward values according to the speed. The feedforward values stored in the storage unit 41 are actually measured current commands u. That is, these feedforward values are current commands that have been subjected to feedback control by the controller 50 and disturbance observer control (described later) by the disturbance observer control system 60, and are corrected current commands that have already been corrected for disturbances and have been suppressed. In the present invention, the stage 11 is operated in advance, and the current command u input to the linear motor 1 at this time with the disturbance suppressed is measured, and the measured current command u is stored in the memory unit 41 as a feedforward value.

[0043] Fig. 5 is an illustrative diagram showing an example of a feedforward value used in feedforward control. In Fig. 5, the command speed is the speed corresponding to the input command u1. As can be seen from Fig. 5, the feedforward value changes over time from the start to the stop of linear motor 1 operation and in accordance with the speed, and is approximately the same as the current command u in Fig. 4.

[0044] The FF corrector 40 performs feedforward control using the feedforward values stored in the memory unit 41. More specifically, the FF corrector 40 performs predetermined processing on the input command u1 from the position command unit 80, selects one of the feedforward values stored in the memory unit 41 in accordance with the input command u1, multiplies the input command u1 by the selected feedforward value, and outputs a current command u2 to the adder 51.

[0045] In this way, the FF corrector 40 uses the corrected current command u, which has already been subjected to disturbance correction, as a feedforward value for feedforward control, so that disturbances can be effectively suppressed.

[0046] The adder 51 adds the current command u2 input to one of its addition input terminals and the current command u3 input to the other addition input terminal, and outputs a current command u4. The current command u4 is output to the second subtractor 71 and the disturbance observer 61.

[0047] Fig. 6 is a block diagram showing the internal configuration of the disturbance observer 61 of the control device 10. In Fig. 6, the same parts as those in Fig. 3 are given the same numbers and symbols. 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 (for example, the position and velocity of an object) from actual measurements containing discrete errors.

[0048] 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 steady-state Kalman filter 100.

[0049] The input terminal of the second parameter unit 87 is connected to the output terminal of the adder 51, and the output terminal of the second parameter unit 87 is connected to one of the addition input terminals of the first adder 91. The output terminal of the first adder 91 is connected to the input terminal of the first integrator 94, and the output terminal of the first integrator 94 is connected to the input terminal of the first parameter unit 86 and the input terminal of the third parameter unit 88. The output terminal of the third parameter unit 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 unit 89 and the input terminal of the fifth parameter unit 90. The output terminal of the first parameter unit 86 is connected to one of the addition input terminals of the second adder 92, and the output terminal of the fourth parameter unit 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 unit 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 subtractor 71 .

[0050] A first parameter section 86, a second parameter section 87, and a third parameter section 88 store state variable parameters A, B, and C of the model (input: current, output: speed), respectively. These parameters A, B, and C are derived according to a MATLAB (registered trademark) program.

[0051] The fourth parameter section 89 calculates the state estimation parameters L of the model. 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 determines the sensitivity to errors that occur between the waveform of the compared model and the waveform of the actual device. If you want to correct even small errors, you need to set this parameter L x Also, set the parameter L d Also, parameter L x Similarly, it is a model gain for specifying the sensitivity in correction.

[0052] In actual implementation, it is preferable to use discretized values for each of these parameters.

[0053] An estimate of the velocity waveform (a velocity waveform when there is no influence of disturbance) when a current command u4 is input to the model from the adder 51 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 estimated value from the model is used to estimate the movement of the dynamic system (the object to be controlled), and the parameter L x Since a fixed value is used as the model gain, it takes the form of a stationary Kalman filter.

[0054] The difference (error) obtained by the subtractor 93 is used to determine an estimated value ^d of the disturbance, and the determined estimated value ^d of the disturbance is subtracted from the current command u4 by the 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.

[0055] The second subtractor 71 receives the current command u4, which has been subjected to feedforward control and feedback control, 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 calculates the difference between the current command u4 and the disturbance estimate ^d and outputs it to the linear motor 1.

[0056] As described above, in the control device 10 according to the present invention, feedback control by the controller 50, feedforward control by the FF corrector 40, and disturbance observer control by the disturbance observer control system 60 are combined.

[0057] That is, in the control device 10 according to the present invention, the control controller 50 performs feedback control for disturbances that occur during operation of the linear motor 1, and the FF corrector 40 performs feedforward control using the current command u, which has already been corrected for the disturbance and suppressed, as a feedforward value, thereby roughly eliminating the effects of the disturbance. Then, the effects of disturbances that cannot be reduced by feedforward control and feedback control are reduced by disturbance observer control. As a result, sufficient compensation can be performed for the disturbance, and the disturbance suppression effect can be improved.

[0058] (Embodiment 2) In the first embodiment, an example has been described in which feedforward control is performed by the FF corrector 40 from the start to the stop of the linear motor 1 (see FIG. 5), but the present invention is not limited to this. Feedforward control may be performed intermittently while the linear motor 1 is operating.

[0059] In the control device 10 according to the second embodiment, only a portion of the corrected current command u is stored as a feedforward value in the storage unit 41. For example, in the corrected current command u, a portion corresponding to an acceleration section of the linear motor 1, a portion corresponding to a constant velocity section of the linear motor 1, a portion corresponding to a deceleration section of the linear motor 1, a portion corresponding to a stop section of the linear motor 1, etc. are stored.

[0060] The FF corrector 40 monitors the speed of the linear motor 1, and performs feedforward control by appropriately selecting a feedforward value according to the speed of the linear motor 1.

[0061] FIG. 7 is an illustrative diagram showing an example of a feedforward value used in feedforward control. In FIG. 7, the command speed is a speed corresponding to the input command u1. The feedforward value shown in FIG. 7 corresponds to the section (the dashed ellipse in FIG. 4) where the command speed is zero in the corrected current command u shown in FIG. 4. In other words, it is a feedforward value corresponding to the stop section of the linear motor 1. As can be seen from FIG. 7, the feedforward value is zero before the command speed becomes zero, but shows a predetermined value after the command speed becomes zero.

[0062] For example, the FF compensator 40 monitors the command speed, and when the command speed becomes zero, that is, when the linear motor 1 is about to stop, performs feedforward control using the feedforward value shown in Fig. 7. This removes disturbances related to stopping the linear motor 1, shortening the settling time of the linear motor 1, that is, allowing the linear motor 1 to stop quickly.

[0063] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0064] 1. Linear motor 10 Control device 11 Stage (Object) 40 FF corrector (first controller) 41 Storage section 50 Controller (second controller) 51 Adder 60 Disturbance observer control system 61 Disturbance Observer 71 Second subtractor (subtractor) 100 Stationary Kalman Filter u Current command (input value)

Claims

1. In a motor control device that performs disturbance correction, A motor control device that performs feedforward control of the motor using the disturbance-corrected input value input to the motor.

2. a storage unit that stores in advance the actual measured values of the input values; a first controller that performs the feedforward control using an actual measurement value of the input value; a second controller that performs feedback control of the motor based on a difference between a position of an object driven by the motor and a position command value for the motor; The motor control device according to claim 1 , further comprising an adder that adds the output value of the first controller and the output value of the second controller and outputs the result to the motor.

3. a disturbance observer control system that determines an estimated value of the disturbance used in the disturbance correction; a subtractor that calculates the difference between the output value of the adder and the estimated value of the disturbance; 3. The motor control device according to claim 2, wherein the subtractor outputs the difference to the motor.

4. 4. The motor control device according to claim 3, wherein the disturbance observer control system has a stationary Kalman filter.

5. A motor control method for controlling a motor by performing disturbance correction, comprising: A motor control method for performing feedforward control of the motor using the disturbance-corrected input value input to the motor.

6. The actual measured values of the input values are stored in advance; performing the feedforward control using an actual measurement value of the input value; feedback control of the motor based on a difference between a position of an object driven by the motor and a position command value for the motor; 6. The motor control method according to claim 5, further comprising the step of adding the value obtained by the feedforward control and the value obtained by the feedback control and outputting the resulting sum to the motor.

7. determining an estimated value of the disturbance to be used for the disturbance correction; 7. The motor control method according to claim 6, further comprising the step of calculating a difference between the added value and the estimated value of the disturbance and inputting the difference to the motor.

8. 8. The motor control method according to claim 7, wherein the estimated value of the disturbance is determined using a stationary Kalman filter.

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