JP4566682B2 - Servo motor control device - Google Patents

Description

  The present invention relates to a servo motor control apparatus using PID control.

  This type of servo motor control device calculates a motor control value by performing a proportional operation, an integral operation and a differential operation based on the deviation between the target rotation amount and the actual rotation amount of the motor to be controlled. On the other hand, feedback control is performed so that the actual rotation amounts coincide with each other (see, for example, Patent Document 1).

  By the way, the motor to be controlled has a structure in which a seal member made of an elastic material is interposed between the drive shaft (output shaft) and the motor housing, and the seal member prevents a foreign substance from entering the motor. There is something to do. The seal member slides between the drive shaft, for example, when the motor rotates. At this time, the seal member bends and deforms as the drive shaft rotates.

  Then, when the drive shaft of such a motor is rotated to a predetermined rotational position, temporarily stopped, and operated to rotate again after a predetermined time has elapsed, at the time of the temporary stop, when the deformed seal member returns to its original shape. The drive shaft is reversely rotated to increase the deviation from the target value. The control device increases the motor control value in the direction in which the seal member bends in order to reduce the deviation, and decreases the control value again when the deviation becomes small. The control value is changed so that the generated torque is balanced to maintain the rotational position of the drive shaft.

  However, such a change in the motor control value causes a minute rotation of the drive shaft, which becomes a vibration of the motor, and in some cases, the vibration continues during the temporary stop period. In particular, when the control gain (control sensitivity) is set high, the motor control value fluctuates quickly, and the motor vibration also increases. Incidentally, FIG. 4 shows the fluctuation of the motor rotation speed when the gain is high. According to FIG. 4, the fluctuation of the motor rotation speed during the temporary stop period after reaching the target position is vibration, and the amplitude thereof is large.

  On the other hand, if the gain is set low in order to reduce the vibration of the motor, the fluctuation of the motor control value becomes moderate, so that the vibration of the motor during the temporary stop period can be reduced. Incidentally, FIG. 5 shows the fluctuation of the motor rotation speed when the gain is low. In the case of FIG. 5, the amplitude of vibration generated during the temporary stop period after reaching the target position is smaller than in the case of high gain, but overshoot occurs immediately before reaching the target position, and it takes time for positioning. It becomes a problem.

Therefore, if the high gain is set before reaching the target position and the high gain is switched to the low gain when the target position is reached, vibration of the motor after reaching the target position is suppressed while suppressing the occurrence of overshoot immediately before reaching the target position. Can be reduced. However, the drive shaft may move due to a sudden change in the motor-generated torque at the moment when the gain is switched, which is not a preferable countermeasure.
JP 2003-174785 A

  The main object of the present invention is to provide a servo motor control device capable of suppressing vibrations generated by increasing the gain while increasing the gain of PID control to suppress the occurrence of overshoot. Is.

  Hereinafter, effective means for solving the above-described problems will be described while showing effects as necessary. In the following, in order to facilitate understanding, the corresponding configuration in the embodiment of the invention is appropriately shown in parentheses, but is not limited to the specific configuration shown in parentheses.

Means 1. The servo motor (direct drive motor (DD motor) 12) having an elastic member (seal member 35) that bends along with the rotation of the drive shaft (drive shaft 32) is a target to be controlled. A motor control value corresponding to the deviation between the rotation amount and the actual rotation amount is calculated, and a predetermined operation is performed on the drive shaft of the servo motor in accordance with the control value. A servo motor control device provided with PID control means (PID compensator 14) that performs pause control when reaching a rotational position,
Determination means (PID compensator 14) for determining whether or not the drive shaft has rotated the target rotation amount and has reached a predetermined rotation position;
When it is determined that the drive shaft has reached a predetermined rotational position, an adjustment unit at the time of stopping that makes an integral value used by the PID control unit constant at a predetermined value according to the bending force of the elastic member based on the determination (Stop adjustment circuit 25);
A servo motor control device comprising:

  According to the means 1, when it is determined by the determination means that the drive shaft has reached the predetermined rotational position, the integral value used in the calculation of the PID control means is bent by the rotation of the drive shaft by the adjustment unit at the time of stop. It is constant at a predetermined value according to the bending force of the generated elastic member. That is, when the drive shaft reaches the target position and temporarily stops, in order to maintain the rotational position of the drive shaft (to make the deviation zero), the bending force of the elastic member and the generated torque of the motor balance. The motor control value calculated by the PID control means varies. In particular, when the control gain is set high, the motor control value fluctuates quickly and a large vibration is likely to occur in the motor. Further, since the deviation is very close to zero at the time of temporary stop, the motor control value is largely controlled by the integral value. That is, the fluctuation of the integrated value is a factor that causes vibration.

  Therefore, when it is determined that the target rotational position has been reached, the change in the integral value that causes the vibration of the motor during the temporary stop is made constant at a predetermined value corresponding to the bending force of the elastic member. It is possible to maintain the torque generated by the motor at the time substantially in balance with the bending force of the elastic member. Thereby, generation | occurrence | production of the fine rotation operation | movement of a drive shaft can be suppressed, and the vibration of a motor can be suppressed small.

  Incidentally, the elastic member includes a seal member that is interposed between the drive shaft and the motor housing and prevents foreign matter from entering the motor through a gap therebetween.

  Mean 2. When it is determined that the drive shaft has reached a predetermined rotational position, the stop-time adjusting means stops the integration calculation in the PID control means based on the determination, and holds the integral value at the time of stop. The servo motor control apparatus according to claim 1.

  According to the means 2, when it is determined that the target rotational position has been reached, the integral calculation in the PID control means is stopped based on the determination, and the integrated value at the time of the stop is held. That is, since the integral value used at the time of temporary stop uses a value corresponding to the bending force of the elastic member at that time, it becomes more reliable to balance the generated torque of the motor and the bending force of the elastic member, and the vibration of the motor can be reduced. It can suppress more reliably. In addition, the calculation load during the temporary stop can be reduced.

Means 3. A timer (timer 26) for measuring a predetermined time (predetermined time t1) after it is determined that the drive shaft has reached a predetermined rotational position;
The servo motor according to means 2, wherein the stop time adjusting means makes the integral value used in the PID control means constant at a predetermined value corresponding to the bending force of the elastic member after the predetermined time has elapsed. Control device.

  According to the means 3, immediately after the determination of reaching the target rotational position is made, the generated torque of the motor, that is, the fluctuation of the integrated value is still large, so this is eliminated by allowing a predetermined time to elapse from the determination, It is possible to more reliably set an integral value that generates a torque that balances the bending force of the elastic member.

  Means 4. 4. The servo motor control apparatus according to claim 1, wherein the servo motor is a direct drive motor that directly drives a load device by the drive shaft.

  According to the means 4, vibration can be suitably suppressed even in such a direct drive motor (DD motor). Further, since the DD motor directly drives the load device, vibration generated by the motor is easily transmitted to the load device. Therefore, the significance of applying to such a DD motor is great.

  Hereinafter, an embodiment in which the present invention is embodied in a motor control device used in a DD motor (direct drive motor) will be described with reference to the drawings.

  As shown in FIG. 1, the motor control device 11 includes a PID compensator 14 as a PID control unit and a determination unit that controls the operation of the DD motor 12. A target rotation amount calculation circuit 15 is connected via an adder 16 to the input side of the PID compensator 14. The target rotation amount calculation circuit 15 calculates the target rotation amount of the DD motor 12, and the calculation signal is output to the adder 16. The target rotation amount in the present embodiment refers to a target rotation angle that is a rotation target of the DD motor 12. In addition, the target rotational speed, the target rotational speed, a combination of these, and the like are included. The DD motor 12 is connected to the output side of the PID compensator 14 via a filter circuit 17 and a driver 18.

  Here, the DD motor 12 of the present embodiment is configured as shown in FIG. That is, as shown in FIG. 2A, the DD motor 12 has a substantially cylindrical motor housing 31 having a housing space inside, and various motor components are housed in the housing 31. . The motor housing 31 has an end surface portion 31a with one end in the axial direction extending radially inward, and a circular shaft insertion hole through which a drive shaft (output shaft) 32 is inserted at the center of the end surface portion 31a. 31b is formed.

  As shown in FIG. 2B, the drive shaft 32 is rotatably supported by a bearing 34 or the like with respect to a support member 33 in the motor housing 31. A disk-like flange portion 32a is formed at a portion of the drive shaft 32 facing the shaft insertion hole 31b, and a ring-shaped seal member 35 is provided between the outer peripheral portion 32b of the flange portion 32a and the shaft insertion hole 31b. Is installed. The seal member 35 is configured to be impregnated with an elastic material, and closes the gap between the outer peripheral portion 32b of the flange portion 32a and the shaft insertion hole 31b to prevent foreign matter from entering the motor 12. To do. Incidentally, the seal member 35 slides between the drive shaft 32 when the DD motor 12 rotates. The drive shaft 32 of the DD motor 12 is directly connected to a load device (not shown).

  The DD motor 12 includes an actual rotation amount detection encoder 19. In the block diagram shown in FIG. 1, the actual rotation amount detection encoder 19 and the DD motor 12 are drawn separately for convenience of explanation. The actual rotation amount detection encoder 19 detects the actual rotation amount at which the DD motor 12 is actually rotating, and the detection signal is output to the adder 16. The actual rotation amount in the present embodiment refers to an actual rotation angle when the DD motor 12 is actually rotating. In addition to this, the actual rotational speed, the actual rotational speed, a combination of these, and the like are included. Then, a deviation between the actual rotation amount detected by the actual rotation amount detection encoder 19 and the target rotation amount of the DD motor 12 calculated by the target rotation amount calculation circuit 15 is calculated by the adder 16, and the calculation signal Is output to the PID compensator 14.

  The PID compensator 14 includes a ROM 21 and a RAM 22. The ROM 21 stores various PID control programs necessary for the operation of the motor control device 11. In the present embodiment, the operation of the DD motor 12 in accordance with this control program is such that the drive shaft 32 rotates at a predetermined rotation amount (target rotation amount), pauses at a predetermined rotation position (target rotation position), and a predetermined time has elapsed. Later, it is rotated by a predetermined rotation amount set next. That is, the DD motor 12 (drive shaft 32) is operated by repeating the rotation operation, the temporary stop, and the rotation operation again. In addition, the RAM 22 temporarily stores data obtained with the execution of the PID control program, for example, a proportional calculation result, an integral calculation result, a differential calculation result, and the like.

  Further, the PID compensator 14 calculates a motor control value by PID control in accordance with the deviation between the target rotation amount and the actual rotation amount. More specifically, the PID compensator 14 calculates a motor control value by performing a proportional operation, an integral operation, and a differential operation on the deviation between the target rotation amount of the DD motor 12 and the actual rotation amount. In the PID control of the present embodiment, the control gain (control sensitivity) is set high so that overshoot does not occur. The PID compensator 14 outputs a motor control value to the driver 18 via the filter circuit 17, and the driver 18 outputs a control current based on the motor control value to perform a predetermined operation on the DD motor 12. Let it be done.

  Further, the PID compensator 14 determines whether or not the drive shaft 32 of the DD motor 12 has rotated the target rotation amount and reached the target rotation position based on the detection result from the actual rotation amount detection encoder 19. Yes. When the PID compensator 14 determines that the drive shaft 32 has reached the target rotational position, the timer 26 counts the predetermined time t1. When the predetermined time t1 elapses, the stop adjustment circuit 25 as a stop adjustment means stops the integration calculation of the PID compensator 14 and holds the integration value at the stop time (see FIG. 3). .

  Here, the DD motor 12 is provided with the seal member 35 as described above, and the seal member 35 bends and deforms as the drive shaft 32 rotates. When the drive shaft 32 reaches the target position and temporarily stops, the bending force of the seal member 35 and the generated torque of the DD motor 12 are maintained in order to maintain the rotational position of the drive shaft 32 (to make the deviation zero). If they are balanced, the motor control value fluctuates. In particular, when the gain is set high as in the present embodiment, the motor control value fluctuates quickly and large vibrations are likely to occur. Further, since the deviation is very close to zero at the time of temporary stop, the motor control value is largely controlled by the integral value. That is, the fluctuation of the integrated value is a factor that causes vibration.

  Therefore, when it is determined that the target rotational position has been reached, the stop adjustment circuit 25 stops the integration calculation of the PID compensator 14 after a predetermined time t1, and the PID compensator 14 holds the integration value at the stop time. . Therefore, since the integral value that causes the vibration of the DD motor 12 at the time of the temporary stop is constant, the torque generated by the DD motor 12 at this time is maintained in a state of being substantially balanced with the bending force of the seal member 35. Is done. In this case, external noise can be dealt with by proportional calculation and differential calculation. Thereby, generation | occurrence | production of the fine rotation operation | movement of the drive shaft 32 is suppressed, and the vibration of the DD motor 12 is suppressed small.

  Incidentally, in the DD motor 12 to be controlled this time, a time when the balance between the generated torque and the bending force of the seal member 35 is suitable is measured in advance by experiment, and the predetermined time t1 is set from the measurement result. Yes. For example, in the present embodiment, when the drive shaft 32 reaches the target rotation position, the speed fluctuation cycle (vibration cycle) of the drive shaft 32 gradually increases, and the time during which the cycle is longer than the predetermined cycle is tested in advance. And a predetermined time t1 is set from the measurement result. That is, since the fluctuation of the torque generated by the DD motor 12, that is, the integral value is still large at the predetermined time t1 immediately after the above determination, the integral value is not held to eliminate this.

  FIG. 3 shows the fluctuation of the motor rotation speed in the present embodiment. The fluctuation of the motor rotation speed during the temporary stop period after reaching the target position represents the vibration of the DD motor 12. According to FIG. 3, after a predetermined time t1 has elapsed since reaching the target position, the integration calculation is stopped, and the integrated value at the time of the stop is kept constant. Along with this, the vibration of the DD motor 12 is extremely suppressed.

  According to the embodiment described above in detail, the following excellent effects can be obtained.

  In the present embodiment, when it is determined that the drive shaft 32 has reached the predetermined rotational position, the stop adjustment circuit 25 uses the integral value used in the calculation of the PID compensator 14 as a seal that causes deflection as the drive shaft 32 rotates. A predetermined value corresponding to the bending force of the member 35 is constant. In this case, the stop adjustment circuit 25 holds the integrated value after a predetermined time t1 has elapsed since the determination. That is, when it is determined that the target rotational position has been reached, the fluctuation of the integrated value that causes the vibration of the DD motor 12 during suspension (particularly large amplitude at high gain) depends on the bending force of the seal member 35. Therefore, the generated torque of the motor at this time is maintained in a state substantially balanced with the bending force of the elastic member. Thereby, generation | occurrence | production of the micro rotation operation | movement of the drive shaft 32 is suppressed, and the vibration of the DD motor 12 can be suppressed small.

  In particular, since the DD motor 12 directly drives the load device, vibration generated by the DD motor 12 is easily transmitted to the load device. Therefore, the significance of applying to such a DD motor 12 is great.

  Further, in this embodiment, when it is determined that the target rotational position has been reached, the stop adjustment circuit 25 holds the integrated value after a predetermined time t1 has elapsed from the determination. That is, since the integral value used at the time of temporary stop uses a value corresponding to the bending force of the seal member 35 at that time, it is more reliable to balance the generated torque of the DD motor 12 and the bending force of the seal member 35. The vibration of the DD motor 12 can be more reliably suppressed. In addition, the calculation load during the temporary stop can be reduced.

  Moreover, the adjustment circuit 25 at the time of a stop is made to hold | maintain with the integrated value after predetermined time t1 progress from the determination. This is because immediately after the determination that the target rotational position has been reached, the torque generated by the DD motor 12, that is, the fluctuation of the integral value is still large, so this is eliminated by elapse of a predetermined time t 1 from the determination, It is possible to more reliably set an integral value at which a torque that balances the bending force of the seal member 35 is generated.

  In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

  In the above embodiment, when it is determined that the target rotational position has been reached, the integration calculation is stopped after the lapse of the predetermined time t1, and the integration value at the time of the stop is held, but the predetermined value set in advance is used. Also good.

  In the above-described embodiment, the predetermined time t1 is set in advance, but the predetermined time t1 may be adjusted in a timely manner. Further, the predetermined time t1 may be variable from time to time according to the operation of the DD motor 12 or the like. If the predetermined time t1 is not particularly necessary, the integral value may be made constant immediately after the determination that the target rotational position has been reached.

  In the embodiment described above, the motor 12 having the seal member 35 is used. However, the motor 12 may be implemented using another elastic member that is bent as the drive shaft 32 rotates. In addition, even in a motor that drives a load device through a joint with low rigidity, such as an elastic member, or a motor that drives a drive mechanism having a member with low rigidity in the load device, a member with low rigidity in the joint or drive mechanism is used. Since the bending occurs with the rotation of the drive shaft 32, the motor may be implemented.

  In the above embodiment, the load motor is directly applied to the DD motor 12. However, the load motor may be applied to a servo motor having a speed reduction mechanism, a drive transmission mechanism, or the like interposed therebetween.

It is a block diagram which shows the electric constitution of the servomotor control apparatus of one Embodiment. (A) is a perspective view of a motor, (b) is sectional drawing of the mounting part of a sealing member. It is a wave form diagram which shows the fluctuation | variation of the motor rotational speed and integral value of this form. It is a wave form diagram which shows the fluctuation | variation of the motor rotational speed at the time of the conventional control implementation made into high gain. It is a wave form diagram which shows the fluctuation | variation of the motor rotational speed at the time of the conventional control implementation made into low gain.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Direct drive motor (DD motor), 14 ... PID compensator (PID control means, determination means), 25 ... Stop adjustment circuit (stop adjustment means), 26 ... Timer 26, 31 ... Motor housing, 32 ... Drive Shaft 35 ... Seal member (elastic member), t1 ... Predetermined time.

Claims (4)

A servo motor control device having a servo motor that drives a load device as a control target, and at least one of the load device and the servo motor includes an elastic member that bends with the drive,
A motor control value corresponding to the deviation between the target rotation amount and the actual rotation amount is calculated using PID control, and a predetermined operation is performed on the drive shaft of the servo motor in accordance with the control value. A control means for performing a pause control when the rotation amount is rotated and reaches a predetermined rotation position;
Determination means for determining whether or not the drive shaft has rotated the target rotation amount and has reached a predetermined rotation position;
If it is determined that the drive shaft has reached a predetermined rotational position, the integral value used by the control means is made constant at a predetermined value so that the torque balances with the bending force of the elastic member based on the determination, and the integration is performed. A stop adjustment means for suppressing vibrations by performing a proportional calculation and a differential calculation in a state where the calculation is stopped ;
With
The servo motor control device according to claim 1, wherein the predetermined value is a value obtained by holding an integral value at the time when the integral calculation is stopped . A servo motor control device having a servo motor that drives a load device as a control target, and at least one of the load device and the servo motor includes an elastic member that bends with the drive,
A motor control value corresponding to the deviation between the target rotation amount and the actual rotation amount is calculated using PID control, and a predetermined operation is performed on the drive shaft of the servo motor in accordance with the control value. A control means for performing a pause control when the rotation amount is rotated and reaches a predetermined rotation position;
Determination means for determining whether or not the drive shaft has rotated the target rotation amount and has reached a predetermined rotation position;
A timer for measuring a predetermined time after it is determined that the drive shaft has reached a predetermined rotational position;
The integral value used by the control means after the predetermined time has passed is constant at a predetermined value that is a torque that balances the bending force of the elastic member, and vibration is controlled by performing proportional and differential calculations while the integral calculation is stopped. A stop-time adjustment means for suppressing
With
The servo motor control device according to claim 1, wherein the predetermined value is a value obtained by holding an integral value at the time when the integral calculation is stopped . A servo motor control device having a servo motor that drives a load device as a control target, and at least one of the load device and the servo motor includes an elastic member that bends with the drive,
A motor control value corresponding to the deviation between the target rotation amount and the actual rotation amount is calculated using PID control, and a predetermined operation is performed on the drive shaft of the servo motor in accordance with the control value. A control means for performing a pause control when the rotation amount is rotated and reaches a predetermined rotation position;
Determination means for determining whether or not the drive shaft has rotated the target rotation amount and has reached a predetermined rotation position;
A timer for measuring a predetermined time after it is determined that the drive shaft has reached a predetermined rotational position;
The integral value used by the control means after the predetermined time has passed is constant at a predetermined value that is a torque that balances the bending force of the elastic member, and vibration is controlled by performing proportional and differential calculations while the integral calculation is stopped. A stop-time adjustment means for suppressing
With
The servo motor controller according to claim 1, wherein the predetermined value is a preset value . 4. The servo motor control device according to claim 1 , wherein the servo motor is a direct drive motor that directly drives a load device by the drive shaft. 5.

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