JP4285057B2 - Servo control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a servo control device for driving a servo motor, and more particularly to a servo control device having a function of extracting characteristics of a machine that is a load of the servo motor .
[0002]
[Prior art]
Conventionally, in order to obtain machine characteristics, as shown in FIG. 7, a sine wave signal is added to a torque command from an FFT analysis measuring instrument, frequency sweep is performed, and frequency characteristics are obtained from the response. That is, as shown in FIG. 6, when the frequency is vibrated and the response is larger than the normal response amplitude, the resonance is resonated, and the response that is small is antiresonance. Alternatively, a dynamic characteristic equation is obtained from speed, position, machine specifications, etc., and inertia, torsion torque, etc. are obtained (for example, refer to Patent Document 1). Alternatively, it was modeled as a two-inertia machine and the mechanical time constant of the two-inertia system was obtained from the speed in a free vibration state (see, for example, Patent Document 2).
[0003]
[Patent Document 1]
JP 2000-112528 A [Patent Document 2]
Japanese Patent Laid-Open No. 5-15186
[Problems to be solved by the invention]
However, in the conventional technology, it is difficult to obtain a frequency characteristic of the response amplitude by adding a sine wave signal to the torque command and taking the frequency characteristic of the response amplitude. There was a problem that peaks and valleys of characteristics could not be obtained easily. In addition, if the amplitude of the sine wave signal is increased to obtain it accurately, it will vibrate greatly and damage the machine. In Patent Document 1, mechanical specifications are required, and there is a problem that characteristics cannot be obtained accurately when there are no specifications. And when the machine vibrated, it didn't work. In Patent Document 2, it is necessary to create a free vibration (resonance) state, and the time constant is obtained from the response speed.
Therefore, the present invention uses a control method that is easy to vibrate and applies vibration to the machine with simulated disturbance torque from the motor, and further suppresses vibration at the resonance frequency of a control method or filter such as a filter. The purpose is to automatically obtain and set machine characteristics from these responses.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is configured as follows.
According to a first aspect of the present invention, there is provided a servo control apparatus including a mechanical frequency characteristic extracting unit that detects and extracts a resonance frequency of a machine serving as a load of the servo motor , wherein the servo motor and the load model or observer are provided. A vibration detection means for detecting a vibration component of the machine by comparing a speed difference obtained by subtracting an actual speed from an estimated speed calculated by using a predetermined detection level, and performing frequency analysis of the vibration component of the speed difference. While increasing the control gain of the vibration component analysis means and the servo control device in stages, a simulated disturbance torque is applied to the torque command for the servo motor, and based on the analysis result of the vibration component analysis means, the machine A processing unit that determines whether the machine is a rigid body or has a resonance frequency, and if the machine has a resonance frequency, extracts the resonance frequency. When, wherein the mechanical frequency characteristic extracting means, and said vibration detecting means, the vibration component analyzing means, the processing means, in those that have been configured.
According to a second aspect of the present invention, the servo control device according to the first aspect of the present invention further comprises a resonance frequency suppressing means for suppressing a resonance frequency of the machine, and the machine has a resonance frequency. In some cases, after the resonance frequency suppression means suppresses the resonance frequency of the machine, the processing means further increases the control gain of the servo control device in steps, while the simulated disturbance torque is added to the torque command for the servo motor. And the anti-resonance frequency of the machine is extracted based on the analysis result of the vibration component analysis means.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a specific embodiment of the present invention will be described with reference to FIG.
In FIG. 1, 1 is vibration detection, 2 is a microcomputer, 3 is a current amplifier, 4 is a base drive circuit, 5 is a power transistor module, 6 is a motor, 7 is an encoder, 8 is a load such as a machine, 9 is a data trace, Reference numeral 10 denotes frequency analysis.
The operation of the circuit configured as described above will be described with reference to the block diagram of FIG.
First, the microcomputer 2 receives commands such as position and speed from an external controller or the like. For example, in the case of a speed command, speed control is performed, current control of the output current command is performed by the current amplifier 3, and the power transistor 5 is driven through the base drive drive circuit 4 to control the motor. Here, in addition to the normal control, the microcomputer 2 can add step-like simulated disturbance torque to the torque command output from the speed control in FIG.
The method for extracting mechanical characteristics of the present invention will be described with reference to the schematic flowchart of FIG.
First, the gain of the control system such as the position loop and the speed loop is set to a low gain, and the operation is performed as shown in FIG. 5 to detect the vibration level peculiar to the machine. In this figure, the maximum value of the vibration amplitude of the differential speed (estimated speed-speed) in normal operation is detected. Processing 1 is performed in the flowchart of FIG.
Here, the vibration detection 1 is detected as vibration when the differential speed (estimated speed−speed) exceeds a certain vibration level. First, the vibration level in normal operation is detected, and a value obtained by multiplying the vibration level by three times is used as the vibration level. The magnification of the vibration level is merely a guideline and may be determined according to the application and situation of the machine. The differential speed (estimated speed−speed) is obtained by calculating the estimated speed from the motor and load model 3 as shown in FIG. Alternatively, as shown in FIG. 3, the estimated speed is calculated from the observer, and the speed is subtracted from the estimated speed. The reason why the vibration detection and the vibration frequency are obtained from the differential speed (estimated speed−speed) is that since only the vibration component remains after the subtraction, it is easy to obtain the vibration amplitude and vibration frequency accurately.
Next, the gain of the control system such as the position loop and the speed loop is set to a low gain, and the simulated disturbance torque is added in steps to the torque command τref in the control block diagram of FIG. Make sure. Processes 2 to 3 in the flowchart of FIG. 9 are performed. Here, if there is no response of a certain level or more, it is considered that the applied simulated disturbance torque has not exceeded the mechanical load, and the simulated disturbance torque is increased. The simulated disturbance torque is increased so that the response is increased to a predetermined level. The level of this response is , for example, the maximum value of the vibration amplitude during normal operation is doubled in the process 1 of the flowchart of FIG. 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.
After determining the magnitude of the simulated disturbance torque, the control gain is increased stepwise at the timing shown in FIG. When the gain is increased as in the processes of flowcharts 4 to 7 in FIG. 9, simulated disturbance torque is added to the torque command, and vibration is confirmed by vibration detection 1. The vibration detection 1 compares the estimated speed-speed amplitude with the vibration detection level as shown in FIG. The vibration level is 1.5 times the previously adjusted response level. One upper limit value is set for the control gain. Several levels lower than one upper limit value can be provided to determine whether the body is rigid.
After applying the simulated disturbance torque, the estimated speed-speed is traced by the data trace 9, and when the vibration is detected exceeding a certain level, the data trace is stopped and the frequency difference analyzed by the frequency analysis 10 is analyzed to analyze the amplitude. A large frequency is calculated. If no vibration is detected by the vibration detection 1 even if the control gain is increased to a certain level, it is determined that the body has no resonance frequency. And when it vibrates, this frequency becomes the resonance frequency of the machine.
If the frequency characteristic of the machine is taken, a resonance frequency fh and an anti-resonance frequency fl may appear as shown in FIG. When there is no resonance frequency, it can be considered as a substantially rigid body. When the resonance frequency fh is suppressed by a filter or a control method (for example, vibration suppression control) that suppresses high-frequency components and the control gain is further increased, vibration is then generated at the antiresonance frequency fl. By measuring this frequency, the anti-resonance frequency can be found, so that mechanical characteristics of the resonance frequency and the anti-resonance frequency can be obtained. In the measurement of the frequency, the vibration component of the estimated speed-speed is data-traced by the data trace 9 as shown in FIG. The obtained frequency becomes the vibration frequency. Since the equal vibration amplitude that exceeds the vibration detection level is a certain level, the amplitude is also somewhat large.
Next, when vibration is detected by the vibration detection 1 in the process of the flowchart 7 of FIG. 9, the application of the simulated disturbance torque is stopped at the timing as shown in FIG. 6, and the gain is lowered to a level that does not vibrate (for example, the Half or the first low gain set). Alternatively, in order to stop vibration reliably, the torque command is reduced or the positional deviation is set to zero for a moment. The process of the flowchart 8 of FIG. 9 is performed.
The measured vibration frequency f0 is set as a vibration suppression filter, for example, a notch frequency of a notch filter, or a high-frequency vibration component is suppressed using an observer or the like.
After suppressing the high frequency vibration, the gain is increased stepwise at the time timing as shown in FIG. 6 as before. When the gain is increased as in the processes of flowcharts 10 to 12 in FIG. 9, simulated disturbance torque is added to the torque command, and vibration is similarly confirmed by vibration detection 1.
After applying the simulated disturbance torque, the estimated speed-speed is traced by the data trace 9, and when the vibration is detected exceeding a certain level, the data trace is stopped and the frequency difference analyzed by the frequency analysis 10 is analyzed to analyze the amplitude. A large frequency is calculated. This frequency is the anti-resonance frequency of the machine.
Next, when vibration is detected by the vibration detection 1 in the process of the flowchart 12 of FIG. 9, the application of the simulated disturbance torque is stopped at the timing as shown in FIG. 6, and the gain is similarly lowered to a level that does not vibrate (for example, the vibration gain Half of that or the low gain you initially set). Alternatively, in order to stop vibration reliably, the torque command is reduced or the positional deviation is set to zero for a moment. The process of the flowchart 13 of FIG. 9 is performed.
In this way, even a machine having a rigid body or having a resonance frequency and an anti-resonance frequency can be applied. And machine characteristics such as resonance frequency and anti-resonance frequency can be understood.
[0007]
【The invention's effect】
As described above, according to the present invention, mechanical characteristics such as a rigid body, a resonance frequency, and an anti-resonance frequency can be easily and automatically obtained without using a special measuring instrument, and used for control. Can do.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a specific embodiment of the present invention.
FIG. 2 is a control block diagram of the present invention.
FIG. 3 is a control block diagram of another embodiment of the present invention.
FIG. 4 is a control block diagram.
FIG. 5 is a timing chart for measuring the speed command, speed, torque waveform and vibration level during normal operation.
FIG. 6 is a timing diagram of measuring the vibration frequency by increasing the gain to generate vibration, lowering the gain when the vibration is generated, and vibration frequency.
FIG. 7 is an example of data trace and FFT analysis.
FIG. 8 is a frequency characteristic of the machine.
FIG. 9 is a schematic flowchart for extracting mechanical characteristics of the present invention.
FIG. 10 is a configuration diagram of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vibration detection 2 Microcomputer 3 Current amplifier 4 Base drive circuit 5 Power transistor module 6, 26, 36, 46, 106 Motor 7, 107 Encoder 8, 108 Load 9 Data trace 10 Frequency analysis 11, 311, 411 Speed control 12 Motor And load model 13 Observer load inertia 14 Observer speed control gain 15 415 Integration 16 Observer speed control integration 17 Observer overall 18 Position loop gain 19 Frequency characteristics FFT analysis measuring instrument 20 Servo control device

Claims (2)

In a servo control device equipped with a mechanical frequency characteristic extracting means for detecting and extracting a resonance frequency of a machine serving as a load of a servo motor,
Vibration detection means for detecting a vibration component of the machine by comparing a speed difference obtained by subtracting an actual speed from an estimated speed calculated using the servo motor and the load model or an observer with a predetermined detection level ; ,
Vibration component analysis means for performing frequency analysis of the vibration component of the speed difference;
While increasing the control gain of the servo control stepwise, applying a simulated disturbance torque to the torque command for the servo motor, and based on the analysis result of the vibration component analysis means, whether the machine is a rigid body or a resonance frequency And a processing means for extracting the resonance frequency if the machine has a resonance frequency, and
The servo control apparatus according to claim 1, wherein the mechanical frequency characteristic extracting means comprises the vibration detecting means, the vibration component analyzing means, and the processing means . The servo control device further includes a resonance frequency suppression means for suppressing the resonance frequency of the machine,
When the machine has a resonance frequency, after the resonance frequency suppression means suppresses the resonance frequency of the machine,
The processing means applies simulated disturbance torque to the torque command for the servo motor while further increasing the control gain of the servo control device stepwise, and based on the analysis result of the vibration component analysis means, 2. The servo control device according to claim 1, wherein an anti-resonance frequency is extracted .

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