JP4692266B2 - Vibration suppression method - Google Patents

Description

  The present invention relates to a method for suppressing vibrations that occur during positioning stop of a servo motor.

  In the motor control field, high-speed and high-precision positioning is required to improve productivity and quality. However, vibrations are generated by the rotation of the motor, and it takes time for positioning to settle. This is because the resonance of the mechanical system is excited by the rotation of the motor and vibration is generated.

As a control method for this vibration, a method has been proposed in which the speed of the motor is detected, whether or not the speed vibrates with a certain amplitude, the presence or absence of resonance is determined, and the gain of the control system is changed. (See, for example, Patent Document 1).
Japanese Patent Laid-Open No. 4-217889

  The problem to be solved is that vibration is generated while the motor is stopped by an external force such as pressure such as air in addition to vibration caused by resonance that is always generated by the operation of the motor. That is, when machining while the workpiece is stopped, the machining accuracy is adversely affected.

  Vibration due to resonance is inherent to the mechanical system and can be suppressed by performing gain adjustment. However, since vibration generated by an external force does not always occur, it has not been considered. However, such a vibration becomes a problem when machining with a highly accurate positioning, that is, when machining a workpiece while the motor is stopped.

  The present invention solves the above-described problems, and an object of the present invention is to provide a method for suppressing vibration generated in a workpiece by external force while the motor is stopped.

In order to solve the above-described problems, the present invention provides a vibration control method for an apparatus in which an external force is applied to a workpiece driven by a motor, and includes a speed command unit, an actual speed detection unit, a speed vibration detection unit, and a vibration. step 1 filter for suppressing the use of a motor control apparatus having a vibration suppression filters plurality generated, it detects that the motor in the previous SL speed command unit is stopped, when it stops the motor vibration having a step 2 of extracting vibration components of actual speed data obtained from the previous SL actual speed detecting means by the vibration detecting section, and a step 3 of setting the filter for the vibration component extracted in step 2 to the vibration suppression filter Suppression method ,
Further, when the stop of the motor is not detected, the step 1 is repeated, and when the stop of the motor is detected, the operation includes the step of moving to the step 2.
Further, in step 2, the vibration component exceeding a certain threshold is held for the plurality of extracted vibration components, and the vibration component is set by setting a filter for at least one vibration component in the vibration suppression filter. Remove,
Further, the step 1, the step 2, and the step 3 are sequentially repeated, the largest vibration component extracted each time is held, and a filter corresponding to the held vibration component is set as the vibration suppression filter. It is a suppression method .

  According to the vibration suppression method of the present invention, the vibration component of the workpiece to be machined while the motor is stopped is extracted, and the vibration component is removed by applying the vibration suppression filter. Can be suppressed. For this reason, the workpiece positioned with high accuracy can be processed with high accuracy.

  In an apparatus in which an external force is applied to a workpiece driven by a motor, a motor control device including a speed command unit, an actual speed detection unit, a speed vibration detection unit, and a vibration suppression filter for suppressing vibration is used. Step 1 for detecting that the motor is stopped by the speed command unit, Step 2 for extracting a vibration component of the actual speed data obtained from the actual speed detection means when the motor is stopped, and Step 2 And setting a vibration suppression filter for the vibration component extracted in step 3. In step 2, for the plurality of vibration components extracted, the vibration component exceeding a certain threshold is held, and at least one vibration component is By setting the filter, the vibration component is effectively removed.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, 1 is a speed command unit that receives a speed command and an actual speed, 2 is a gain-adjustable control unit that receives the output of the speed command unit 1, and 3 is a vibration that receives the output of the control unit 2. The suppression filter is a filter corresponding to a specific frequency and can generate a plurality of filters. 4 is a motor drive circuit for inputting the output of the vibration suppression filter 3, 5 is a motor driven by the motor drive circuit 4, 6 is an actual speed detecting means for detecting the speed of the motor 5, 7 is an output of the vibration suppression filter 3, This is a vibration detector that estimates the inertia and resonance frequency of the load from the output of the speed detector 6. In the present invention, the vibration detection unit 7 detects the stop of the motor by the stop signal from the speed command unit 1, and extracts the vibration component (frequency and level) from the output of the speed detection means 6.

  When suppressing vibration due to resonance, the vibration detection unit 7 detects a vibration component by FFT or the like when the motor 5 is operated, and the vibration suppression filter 3 suppresses vibration by applying a resonance filter for the resonance frequency. . Since the detected resonance frequency is unique to the device, this resonance filter is always applied. Further, it is possible to perform positioning with high accuracy by estimating the inertia of the load from the output of the vibration suppression filter 3 and the output of the speed detection means 6 and adjusting the gain of the control unit 2 from the estimated value.

  In addition to the above-described resonance suppression method, the present invention is characterized in that processing is performed in accordance with steps 1 to 3 shown in FIG. 1 in order to suppress vibration generated in the workpiece by external force while the motor is stopped.

  For this reason, in step 1, the speed command unit 1 detects that the motor 3 is stopped. If the motor 5 is not stopped, step 1 is repeated, and if the stop of the motor 5 is detected, the process proceeds to step 2.

  Next, in step 2, in order to extract the vibration component generated in the workpiece by external force from the motor 5 connected to position the workpiece, the actual speed data obtained via the actual speed detecting means 6 is FFT or the like. This is extracted by the vibration detection unit 7 using frequency analysis. The extracted vibration component is held as the vibration frequency at which the workpiece is generated. If no vibration component is detected in step 2, the filter is not set in step 3.

  In step 3, a filter that suppresses the vibration component is set for the vibration frequency held in step 2. This is the basic step.

  When the drive command to the motor is input, the application of the filter of the present invention is canceled, and after the motor stops, the vibration component at the time of stop is extracted again and the filter is applied. Or the vibration frequency before operation | movement is hold | maintained and a filter is applied again after a motor stop.

  When steps 1 to 3 are repeated, a new vibration component is extracted while maintaining the application of the previously set filter. Returning to step 1, if the stop of the motor 4 is detected, the application of the filter is held, and the process proceeds to step 2. If the motor is being driven, the application of the filter is canceled.

  By the way, in step 2, in order to effectively suppress vibration with respect to the extracted vibration component, a vibration component having a large amplitude is preferentially held. When a plurality of vibration components of the same level are extracted, only one lowest vibration frequency is held, and a filter that suppresses the vibration frequency is set.

  In step 2, only the vibration component exceeding the threshold value may be held. In this case, in step 3, a filter for suppressing at least one vibration frequency held in step 2 is set. For example, if a filter is applied to the lowest vibration frequency among vibration components exceeding a certain threshold, vibration can be effectively suppressed. The threshold value may be set for each frequency band.

  On the other hand, a plurality of filters may be set at the same time for the extracted plurality of vibration components. However, since the filter causes a delay in the control system, it is better to preferentially suppress vibration components having a large amplitude.

  The vibration suppression method of the present invention is useful for an apparatus in which an external force is applied to a workpiece driven by a motor.

Flowchart in the vibration suppression method of the present invention The block diagram of the principal part in this invention

DESCRIPTION OF SYMBOLS 1 Speed command part 2 Control part 3 Vibration suppression filter 4 Motor drive circuit 5 Motor 6 Actual speed detection means 7 Vibration detection part

Claims (1)

In a vibration suppression method for an apparatus in which an external force is applied to a workpiece driven by a motor, vibration in which a speed command unit, an actual speed detection unit, a speed vibration detection unit, and a plurality of filters for suppressing vibration are generated using a motor controller having a suppression filter, a step 1 for detecting that the motor in the previous SL speed command unit is stopped, the actual speed data obtained from the previous SL actual speed detecting means when it stops the motor and step 2 of extracting vibration components in the vibration detector of a vibration suppressing method and a step 3 of setting the filter for the vibration component extracted in step 2 to the vibration suppression filter,
Further, when the stop of the motor is not detected, the step 1 is repeated, and when the stop of the motor is detected, the operation includes the step of moving to the step 2.
Furthermore, the similar step 2, with respect to the plurality of extracted vibration components, to retain the vibration component exceeds a certain threshold, due to setting the filter for at least one vibration component in the vibration suppression filter riff Remove the dynamic components ,
Further, step 1, step 2, sequentially repeated step 3, holds the greatest vibration component extracted each time, and sets the filter corresponding to the retained vibration component in the vibration suppression filter vibrations Suppression method.

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