JP2005204472A5 - - Google Patents

Description

Servo control device and limit gain extraction method thereof

The present invention relates to a method for automatically setting a servo control gain in a servo controller for driving a servo motor, in particular the detection limit value of the servo control gain by detecting the vibration of the O Ri vibration shiso the vibrating means machinery The present invention relates to a servo control device and a limit gain extraction method thereof .

As a limit gain extraction method for a conventional servo control device, a method has been proposed in which the gain is increased to oscillate and the gain is maximized ( see, for example, 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 the flag is not F = 1, the gain adjustment processing ends without performing the process. 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, a vibrating means applying a simulated disturbance torque to the torque command, a vibration detecting means for detecting a vibration of at least the torque command or the based on the motor rotational speed control system by the vibration detecting means, said position control unit and Control gain changing means for changing the control gain of the speed control unit, and when the load is different between forward rotation and reverse rotation of the motor, torque corresponding to the different load is simulated in advance Add to the disturbance torque to obtain a new simulated disturbance torque, increase the control gain, and repeat the process of adding the simulated disturbance torque to the torque command until vibration exceeding a preset level is detected. vibration of the control gain immediately before the detected regarded as critical gain, varying the control gain of the position controller and the speed controller It is characterized in that.

According to a second aspect of the present invention, in the limit gain extraction method of the servo control device according to the first aspect , a difference torque between a forward rotation direction torque and a reverse rotation direction torque when the motor is stopped is preset. When the level is equal to or higher than the level, the difference torque is added to the simulated disturbance torque.

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 the servo control apparatus and a speed calculation means for outputting the motor rotational speed detection signal and calculates the motor rotational speed based on the position detection signal, Vibration means for adding pseudo disturbance torque to the torque command, means for adding torque for the different load to the simulated disturbance torque when the load is different between forward rotation and reverse rotation, Means for adding the difference torque to the simulated disturbance torque when the difference torque between the forward rotation direction torque and the reverse rotation direction torque exceeds a preset level; and at least the torque command or the motor rotation speed it is characterized in further comprising a vibration detecting means for detecting vibration of the control system, a control gain changing means for changing the control gain of the position controller and the speed controller on the basis of the vibration detected on the basis of .

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 . Further, 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.

First, the configuration of the servo control device according to the present invention will be described with reference to FIG.
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 12 . 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.

Next, the operation of the servo control apparatus according to the present invention will be described with reference to FIG.
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. Torque is generated when a drive current flows through the motor 6. 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 signal . 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 1 and the speed control unit 2 are changed via the change 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 exceeds a preset vibration detection level threshold A. If it exceeds, the simulated disturbance torque and the vibration detection level threshold A are determined to proceed to step S55 and must be exceeded. If the applied 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 A may be arbitrarily set as long as the control system does not oscillate. For example, the vibration detection level threshold A is twice the maximum value of the vibration amplitude of the vibration component level detected in step S51. It is preferable to make it about. If the response does not increase even if the simulated disturbance torque is increased to a certain level, the vibration detection level threshold A is lowered. In this way, the magnitude of the simulated disturbance torque and the vibration detection level threshold A 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 exceeds a preset vibration detection level threshold value B. If it exceeds, the control gain immediately before that time proceeds to step S58 as the limit gain, and exceeds it. If not, the process returns to step S55.
The vibration detection level threshold B may be arbitrarily set as long as the control system does not oscillate. For example, the vibration detection level threshold B may be selected to be about 1.5 times the vibration detection level threshold A used in step S54. good.

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 vibration 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. The control gain immediately before the control gain at the time of vibration is generally stored as a limit gain in the storage means in the servo control device. The stored control gain is a limit gain to be detected.

Consider the relationship between simulated disturbance torque and control gain that generates vibration. 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 detection means 12 may be linked with an integral gain, a torque filter, or the like along with the control 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 Example of limit gain 45 vibration 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,
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 rotation speed, control gains of the position control unit and the speed control unit If the load differs between the forward rotation and the reverse rotation of the motor, the torque for the different load is added to a preset simulated disturbance torque to newly When the control gain is increased, the process of adding the simulated disturbance torque to the torque command is repeated until vibration exceeding a preset level is detected, and immediately before the vibration exceeding the level is detected. the control gain is regarded as a limit gain servo control and changes the control gain of the position controller and the speed controller Limit gain extraction method location. 2. The difference 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 is equal to or higher than a preset level. Method for extracting limit gain of servo control device. 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, means for adding torque for the different load to the simulated disturbance torque when the load differs between forward rotation and reverse rotation, Means for adding the difference torque to the simulated disturbance torque when the difference torque between the forward rotation direction torque and the reverse rotation direction torque exceeds a preset level; and at least the torque command or the motor rotation speed Servo control device comprising: vibration detection means for detecting vibration of a control system based on the control signal; and control gain changing means for changing control gains of the position control section and the speed control section based on the vibration detection. .