JP2005204472A - Servo controller and its limit gain extracting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a servo controller capable of extracting a limit gain even when the load on the servo controller is different during forward rotation and reverse rotation without bringing the servo controller into oscillation state and without causing any damage on the machine, and to provide its limit gain extracting method. <P>SOLUTION: The servo controller comprising a shaking means 11, a vibration detecting means 12, and a control gain altering means 14 repeats a processing for applying a simulation disturbance torque, increasing the control gain until a vibration of preset level is detected and then applying a simulation disturbance torque, and sets the control gain immediately before detecting a vibration exceeding the preset level as a limit level. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for automatically setting a servo control gain in a servo control device for driving a servo motor, and more particularly to a method for detecting a limit value of a servo control gain by detecting vibration and vibration by a vibration means of a machine or the like. .

As a limit gain extraction method of a conventional servo control device, a method has been proposed in which a gain is increased to oscillate and the gain is maximized (see Patent Document 1).
FIG. 5 is a flowchart for explaining gain adjustment processing according to the prior art.
In step 500, it is determined whether or not to perform gain adjustment processing. If it is not F = 1, the gain adjustment processing ends without performing, and if F = 1, the process proceeds to step 501.
In step 501, the actual speed data stored in the memory obtained by oscillating the control system is subjected to FFT analysis to obtain the amplitude of the frequency component. Next, the frequency f having the maximum amplitude among the amplitudes detected in step 502 is obtained as fmax. Next, it is determined whether or not the absolute value of the difference between fmax and the set reference frequency fa is smaller than a threshold value ε set for gain adjustment. move on.
In step 504, a value obtained by multiplying the currently set cutoff frequency fn by the value obtained by subtracting fmax from fa and the setting parameter α is set as a new fn.
In step 505, the upper limit value flim of the speed loop band determined by the control system set to fn is calculated. If fn is small, the process proceeds to step 508, and if not small, the process proceeds to step 506.
In step 508, gains K1 and K2 of the speed loop are calculated. Next, in step 509, the index i and the flag F are set to “0”, and the process ends.
In step 506, it is determined whether or not the parameter P is “0”. If “0”, the process proceeds to step 507, and if not “0”, the process proceeds to step 510.
In step 507, the value of P is set to “1”, the speed control loop is set to PI control, and fn is set to the initial value fn0, and the process proceeds to step 508.
In step 510, fn is set to flim and the process proceeds to the next. In step 511, the speed loop gains K1 and K2 are determined and the adjustment of the speed loop gain is completed.
Thus, when the speed control is performed with the determined value, the desired speed control with no gain and a large gain is performed.
Japanese Patent Laid-Open No. 2-261683 (page 8-9, FIG. 7)

However, in the conventional example, the gain of the servo control device must be increased to make it oscillate, and there is a problem that the maximum gain value cannot be obtained, and it takes time to extract the limit gain and may damage the machine. . In addition, when the load is different between forward rotation and reverse rotation, such as when a gravity load is applied to the servo control device, there is also a problem that the ease of oscillation changes and the maximum gain value cannot be obtained stably.
The present invention has been made in view of such problems, and does not cause the servo control device to oscillate and does not damage the machine. Also, the load of the servo control device differs between forward rotation and reverse rotation. An object of the present invention is to provide a servo control device and its limit gain extraction method capable of extracting a limit gain even in the case.

In order to solve the above problems, the present invention is configured as follows.
The invention according to claim 1 inputs a position command and a motor rotation position detection signal, performs position control so that the motor rotation position detection signal matches the position command, and outputs a speed command; A speed control unit that inputs a speed command and a motor rotational speed detection signal, performs speed control so that the motor rotational speed detection signal matches the speed command, and outputs a torque command; and a torque generated by the motor by inputting the torque command A torque control unit that performs torque control so as to match the torque command and outputs a motor drive current, a position detector that detects the rotational position of the motor and outputs the motor rotational position detection signal, and the motor rotational position detection A limit gain extraction of a servo control device comprising a speed calculation means for calculating a motor rotation speed based on the signal and outputting the motor rotation speed detection signal In law,
The simulated disturbance torque is added to the torque command by the vibration means, the vibration of the control system is detected based on at least the torque command or the motor rotation speed by the vibration detection means, and the load is detected during forward rotation and reverse rotation of the motor. If they are different, the simulated disturbance torque obtained by adding the torque for the different load to the preset simulated disturbance torque is added to the torque command, and the control gene is raised until the vibration exceeding the preset level is detected. The process of applying disturbance torque is repeated, the control gain immediately before detecting the vibration exceeding the level is regarded as the limit gain, and the control gain changing means changes the control gains of the position control unit and the speed control unit. It is a feature.

  According to a second aspect of the present invention, the torque is added to the simulated disturbance torque when the difference torque between the forward rotation direction torque and the reverse rotation direction torque when the motor is stopped exceeds a preset level. It is characterized by this.

According to a third aspect of the present invention, there is provided a position control unit that inputs a position command and a motor rotation position detection signal, performs position control so that the motor rotation position detection signal matches the position command, and outputs a speed command. A speed control unit that inputs the speed command and the motor rotation speed detection signal, performs speed control so that the motor rotation speed detection signal coincides with the speed command, and outputs a torque command; A torque control unit that performs torque control so that the generated torque matches the torque command and outputs a motor drive current; a position detector that detects a rotation position of the motor and outputs the motor rotation position detection signal; and the motor rotation In a servo control device comprising a speed calculation means for calculating a motor rotation speed based on a position detection signal and outputting the motor rotation speed detection signal,
Excitation means for applying step-like simulated disturbance torque to the torque command, vibration detection means for detecting vibration of the control system based on the torque command or the motor rotational speed, control of the position control unit and the speed control unit And a control gain changing means capable of changing the gain.

  According to the present invention, since the servo control device is not oscillated, the limit gain can be extracted without damaging the machine, and it does not take time to extract the limit gain. According to the second aspect of the present invention, it is possible to provide a servo control device and its limit gain extraction method that can extract a limit gain even when the load of the servo control device differs between forward rotation and reverse rotation.

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

Although various functions and means are built in the actual servo control device, only the functions and means related to the present invention will be described and described in the figure.
FIG. 1 is a block diagram of a servo control apparatus to which the present invention is applied. In FIG. 1, 1 is a position control unit, 2 is a speed control unit, 3 is a torque control unit, 4 is a position detector, 5 is speed calculation means, 6 is a motor, 7 is a machine, and 8 is a torque transmission mechanism.
Further, 11 is an excitation means, 12 is a vibration detection means, 13 is an adder, and 14 is a control gain changing means.

The position control unit 1 inputs a position command and a motor rotation position detection signal and outputs a speed command to the speed control unit 2. The speed control unit 2 inputs the speed command and the motor rotation speed detection signal, and outputs a torque command to the adder 13 and the vibration detection means. The adder 13 inputs the torque command and the simulated disturbance torque signal, and outputs a combined torque command to the torque control unit 3. The torque control unit 3 inputs the combined torque command and outputs a motor drive current to the motor 6. A torque transmission mechanism 8 and a position detector 4 are mounted on the motor 6. The torque transmission mechanism 8 transmits the torque generated by the motor 6 to the load 7. The position detector 4 outputs the motor rotation position detection signal to the position controller 1 and the speed calculation means 5. The speed calculation means 5 inputs the motor rotation position detection signal and outputs the motor rotation speed detection signal to the speed control unit 2 and the vibration detection means 12. The vibration detection means 12 inputs the torque command or the motor rotation speed detection signal, and outputs a vibration means control signal to the vibration means 11 and a control gain change signal to the control gain change means 14. The vibration means 11 receives the vibration means control signal and outputs the simulated disturbance torque signal to the adder 13. The control gain changing means 14 receives the control gain changing signal and changes the control gains of the position control unit 1 and the speed control unit 2.

The position control unit 1 performs a control calculation so that the motor rotation position detection signal coincides with the position command, and calculates the speed command. The speed controller 2 performs a control calculation so that the motor rotation speed detection signal matches the speed command, and calculates the torque command. The adder 13 adds the torque command and the simulated disturbance torque to calculate the combined torque command. The torque control unit 3 performs a torque control calculation based on the combined torque command and causes a motor driving current to flow to the motor 6. When drive current flows through the motor 6, torque is generated. The position detector 4 detects the rotational position of the motor 6. The speed calculation means 5 calculates the motor rotation speed detection signal based on the motor rotation position detection signal. The vibration means 11 generates a step-like simulated disturbance torque signal at a preset level according to the vibration means control. The vibration detection means 12 extracts a vibration component included in the torque command or the motor rotation speed detection signal, and controls the control gain according to the control gain change signal depending on whether the vibration component exceeds a preset level. The control gains of the position control unit and the speed control unit are changed via the changing unit 14, and the vibration unit 11 is turned on / off by the vibration unit control signal.

FIG. 2 is a flowchart for explaining a limit gain extraction method of the servo control apparatus of the present invention. In FIG. 2, first, in step S51, normal operation is performed, and the level of the vibration component of the machine is detected by the vibration detection means 12. FIG. 3 shows typical response waveforms when the servo control device is normally operated. In FIG. 3, 31 is a speed command, 32 is a response speed, 33 is a torque, and 34 is a level of a vibration component during operation.
Next, in step S52, the moving direction is changed, and the torque at the time of movement and at the time of stop is measured. This can generally be obtained from the magnitude of the motor drive current. Now, assuming that the torque in the forward direction when the motor is stopped is trq1, and the torque in the reverse direction is trq2, the load torque trq is
trq = (trq1 + trq2) / 2
It becomes. Here, the addition is performed by changing the moving direction because the friction torque can be canceled by the addition. The same applies to the movement. Further, if the load torque trq is equal to or higher than a preset level, it is determined that the unbalanced load is different between forward rotation and reverse rotation such as gravity load, and this load torque is added to the subsequent simulated disturbance torque signal to be corrected. .

Next, in step S53, the gain of the control system such as the position loop and the speed loop is set to a low gain, and a simulated disturbance torque signal is added by the vibration means 11. In step S54, it is determined whether or not the vibration component has exceeded a preset vibration detection level threshold value. If so, the process proceeds to step S55, assuming that the simulated disturbance torque and vibration detection level threshold value have been determined. Since the simulated disturbance torque has not exceeded the load on the machine, the process proceeds to step S59. In step S59, the level of the simulated torque signal is increased and the process returns to step S53.
The vibration detection level threshold value may be arbitrarily set as long as the control system does not oscillate. For example, the vibration detection level threshold value is about twice the maximum value of the vibration amplitude of the vibration component level detected in step S51. It is preferable to make it. If the response does not increase even if the simulated disturbance torque is increased to a certain level, the response detection level is lowered. In this way, the magnitude of the simulated disturbance torque and the detection level of the response are adjusted.

In step S55, the control gain is increased. Next, a simulated disturbance torque signal is added by the vibration means 11 in step S56. Next, in step S57, it is determined whether or not the vibration component has exceeded a preset vibration detection level threshold value. If it has exceeded, the process proceeds to step S58 with the gain immediately before that being the limit gain, and if not exceeded, The process returns to step S55.
The vibration detection level threshold value may be arbitrarily set as long as the control system does not oscillate. For example, the maximum vibration amplitude level of the vibration component detected in step S51 and the vibration detection level threshold value in step S54. It is preferable to set a value between the vibration detection level threshold value used and may be selected to be about 1.5 times the maximum value of the vibration amplitude of the vibration component level detected in step S51.

FIG. 4 is a timing chart for explaining the procedure for extracting the limit gain. In FIG. 4, 41 is a timing indicating an operation of increasing the gain of the control system, 42 is a timing of applying a simulated disturbance torque signal, and 43 is an example of a vibration component detected based on the torque or speed detection signal. 44 is an extracted limit gain, and 45 is an example of a signal detection level threshold.
In step S58, the limit gain is extracted, and the control gain is lowered to a level that does not vibrate, for example, half of the oscillated gain or a low gain that is initially set.
In order to stop vibration reliably, the torque command is narrowed down or the position deviation is set to zero for a moment. Then, the gain immediately before the gain at the time of vibration is generally stored as a limit gain in storage means in the servo control device. The stored gain is the limit gain to be detected.

Now consider the relationship between simulated disturbance torque and gain at which vibration occurs. As the simulated disturbance torque is increased, the impact on the machine is also increased, and the control gain is reduced so that no vibration is generated. This is the reason why the impact is reduced and the control gain is increased by smoothing the machine by accelerating / decelerating the machine or inserting a filter.
In this embodiment, the simulated disturbance torque is directly input to the torque command. However, the torque can be generated even by moving a minute distance, so that the same can be done. Further, the vibration detecting means 12 may be linked with an integral gain, a torque filter or the like according to the gain.

  INDUSTRIAL APPLICABILITY The present invention can be used for a positioning control servo control device for a semiconductor manufacturing apparatus and a servo control device for driving a machine tool or an industrial robot.

The block diagram of the servo control apparatus to which this invention is applied. The flowchart explaining the limit gain extraction method of the servo control apparatus of this invention. Typical response waveform when the servo controller is operated normally. The timing diagram explaining the procedure which extracts the limit gain of this invention. The flowchart explaining the gain adjustment process by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Position control part 2 Speed control part 3 Torque control part 4 Position detector 5 Speed calculation means 6 Motor 7 Machine 8 Torque transmission mechanism 11 Excitation means 12 Vibration detection means 13 Adder 14 Control gain change means 31 Speed command 32 Response speed 33 Torque 34 Level of vibration component during operation 41 Timing indicating operation of increasing control system gain 42 Timing of applying simulated disturbance torque signal 43 Example of vibration component detected based on torque or speed detection signal 44 Extracted Limit gain 45 Example of signal detection level threshold

Claims (3)

A position control unit that inputs a position command and a motor rotation position detection signal, performs position control so that the motor rotation position detection signal matches the position command, and outputs a speed command; and the speed command and the motor rotation speed detection signal A speed control unit that performs speed control and outputs a torque command so that the motor rotation speed detection signal matches the speed command, and the torque command is input and the generated torque of the motor matches the torque command. A torque control unit that performs torque control and outputs a motor drive current, a position detector that detects a rotation position of the motor and outputs the motor rotation position detection signal, and calculates a motor rotation speed based on the motor rotation position detection signal In a limit gain extraction method for a servo control device comprising a speed calculation means for outputting the motor rotation speed detection signal,
The simulated disturbance torque is added to the torque command by the vibration means, the vibration of the control system is detected based on at least the torque command or the motor rotation speed by the vibration detection means, and the load is detected during forward rotation and reverse rotation of the motor. If they are different, the simulated disturbance torque obtained by adding the torque for the different load to the preset simulated disturbance torque is added to the torque command, and the control gene is raised until the vibration exceeding the preset level is detected. The process of applying disturbance torque is repeated, the control gain immediately before detecting the vibration exceeding the level is regarded as the limit gain, and the control gain changing means changes the control gains of the position control unit and the speed control unit. A method for extracting a limit gain of a servo control device.   2. The servo according to claim 1, wherein the torque is added to the simulated disturbance torque when the difference between the forward rotation direction torque and the reverse rotation direction torque when the motor is stopped is equal to or higher than a preset level. Control device limit gain extraction method. A position control unit that inputs a position command and a motor rotation position detection signal, performs position control so that the motor rotation position detection signal matches the position command, and outputs a speed command; and the speed command and the motor rotation speed detection signal A speed control unit that performs speed control and outputs a torque command so that the motor rotation speed detection signal matches the speed command, and the torque command is input and the generated torque of the motor matches the torque command. A torque control unit that performs torque control and outputs a motor drive current, a position detector that detects a rotation position of the motor and outputs the motor rotation position detection signal, and calculates a motor rotation speed based on the motor rotation position detection signal And a servo control device comprising speed calculation means for outputting the motor rotation speed detection signal,
Excitation means for applying simulated disturbance torque to the torque command, vibration detection means for detecting vibration of the control system based on at least the torque command or the motor rotational speed, and control gains of the position control unit and the speed control unit A servo control device comprising: a control gain changing means capable of changing.

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