JP5402649B2 - Notch filter and motor control device having the same - Google Patents

Description

The present invention maintains a gain characteristic of a center frequency in a notch filter, can improve a gain characteristic and a phase characteristic without having a vibration pole, and can be designed in more detail than a normal notch filter. The present invention relates to a motor control device including the same.

A conventional motor control device including a notch filter includes a plurality of notch filters, and when oscillation due to mechanical resonance occurs, the notch filter selection unit selects the oscillation frequency estimated by the frequency estimation unit and the plurality of notch filters. Based on the valid / invalid setting state and notch frequency, an appropriate one is selected from the notch filters, and the notch frequency setting means sets the oscillation frequency as the notch frequency to the selected notch filter. Even when the mechanical device has multiple mechanical resonances, each oscillation caused by the multiple mechanical resonances can be suppressed, and even if the mechanical device's resonant frequency changes for some reason, such as aging, the notch frequency of the notch filter Is described in a stable and automatic manner (for example, Patent Document 1).

JP 2006-288124 A (page 3-5, FIG. 1)

  A conventional motor control device including a notch filter includes a plurality of notch filters in series. However, when a notch filter having a certain transfer function is arranged in series, the phase characteristics and gain characteristics are added together. The phase below the lowest resonance frequency is greatly delayed, resulting in a problem that the control gain in the motor control device does not increase and the position response becomes slow.

The present invention has been made in view of such problems, and maintains the gain characteristics of the center frequency in the notch filter, improves the gain characteristics other than the center frequency without having a vibration pole, and has a frequency below the center frequency. Provided are a notch filter and a motor control device including the notch filter that can improve the phase delay and can be designed in more detail than the normal notch filter.

In order to solve the above problem, a typical configuration of the present invention is configured as follows.
The notch filter is a notch filter that lowers the gain characteristic of the specific frequency in the input signal, the first notch filter that inputs the input signal and outputs the first signal with the gain characteristic of the specific frequency lowered, and the input signal A subtractor that subtracts the first signal from the first signal, a second notch filter that receives the output signal of the subtractor and outputs a second signal with a reduced gain characteristic at a specific frequency, and the second signal and gain And an adder for adding the first signal and the output signal of the gain multiplier to output the output signal of the adder with respect to the input signal. Is.

Another typical configuration of the present invention is configured as follows.
A motor control device generates and outputs a position command, and a control unit that calculates and outputs a power supply command by performing control calculation so that the position command and the motor position detected by the position detector match. And a motor control device for driving a control target composed of a motor with a position detector and a load coupled to the motor, wherein the gain characteristic of the specific frequency in the position command is lowered with respect to the position command. A notch filter that outputs a new position command, and the notch filter receives the position command and outputs a first signal with a reduced gain characteristic of the specific frequency. And a subtractor for subtracting the position command and the first signal; and an output signal of the subtractor is input, and a second signal with a reduced gain characteristic of the specific frequency is output. A notch filter, a gain multiplier that multiplies the second signal and a gain, an adder that adds the output signal of the first signal and the gain multiplier, and the position command On the other hand, the output signal of the adder is output as the new position command.

According to the representative configuration of the present invention, the signal component removed by the first notch filter is again passed through the second notch filter and added back by multiplying by a gain K. Therefore, the center frequency removed by the first notch filter is used. It is possible to restore components other than the above, and it is possible to reduce gain reduction and phase delay other than the center frequency due to the notch filter. Compared to a normal notch filter, gain characteristics other than the center frequency can be improved without having a vibration pole, and phase delay below the center frequency can be improved. In the case of having, the resonance of the system other than the frequency set by the notch filter is not excited, the vibration is not increased so much, and the response of the system can be improved. Furthermore, since the characteristics of the filter can be designed in more detail than a normal notch filter, an optimum filter can be designed according to the purpose of use.

According to another typical configuration of the present invention, since the phase delay can be reduced while suppressing the vibration as compared with the case where a normal notch filter is applied to the motor control device, the positioning response of the motor can be improved.

The block diagram of the motor control apparatus in 1st Example of this invention. The block diagram explaining the structure of the notch filter in 1st Example of this invention. The block diagram of the motor control apparatus in 2nd Example of this invention. The block diagram of the motor control apparatus in 3rd Example of this invention. Simulation results when a normal notch filter is applied to a motor controller Simulation results when the notch filter in the first embodiment of the present invention is applied to a motor control device Simulation results when the notch filter in the second embodiment of the present invention is applied to a motor control device Input / output frequency characteristic diagram of a notch filter in an embodiment of the present invention

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

FIG. 1 is a block diagram of a motor control device according to a first embodiment of the present invention. In the figure, the motor control device includes a command generation unit 1, a notch filter 2, a position / speed control unit 3, and a current control unit 4, and power for driving a motor 5 (control target 7) coupled with a load 6. Supply.
The command generation unit 1 generates a position command xr for driving the controlled object 7. The notch filter 2 described later reduces the gain of the frequency ωn from the position command xr and outputs a new position command xr ′. The position / speed control unit 3 performs control calculation so that the new position command xr ′ and the motor position xm detected by the position detection unit 8 coincide with each other, and outputs a torque command tref. Here, a case where position proportional and velocity proportional integral control is performed is taken as an example, but the control method is not limited to this. The current control unit 4 performs current control according to the torque command tref and outputs a voltage command vr. The motor control device includes a power converter that converts the voltage command vr into electric power, but a detailed description thereof is omitted here. Further, when the position / velocity control unit 3 and the current control unit 4 are regarded as one control unit, this control unit can be regarded as outputting a power supply command to the controlled object 7 to be driven.

FIG. 2 is a block diagram illustrating the configuration of the notch filter in the first embodiment of the present invention. In the figure, the notch filter 20 includes a first notch filter 21, a second notch filter 23, a subtracter 22, a gain multiplier 24, and an adder 25.
The first notch filter 21 has a transfer function represented by Expression (1).

Where ωn: notch center frequency, ζ1: molecular side attenuation coefficient,
ζ2: Denominator side attenuation coefficient.
The second notch filter 23 has a transfer function represented by the equation (2), and has the same center frequency ωn as that of the first notch filter 21.

Here, ωn: Notch center frequency, ζ3: Molecular side attenuation coefficient,
ζ4: A denominator-side attenuation coefficient.

The subtracter 22 outputs a signal ex obtained by subtracting the output signal xa1 of the first notch filter 21 from the input signal of the first notch filter 21. The gain multiplication unit 24 multiplies the output signal xa2 of the second notch filter 23 to which the signal ex is input by a gain K. The adder 25 adds the output signal xa1 of the first notch filter 21 and the output signal of the gain multiplier 24.

A transfer function from the input signal to the output signal of the notch filter 20 configured as described above is expressed by Expression (3).

If the denominator-side attenuation coefficient ζ2 in the first notch filter 21 and the denominator-side attenuation coefficient ζ4 in the second notch filter 23 are 1 or more, this filter has no vibration pole.

Next, simulation results when the notch filter according to the first embodiment of the present invention and a normal notch filter (configured only by the first notch filter) are respectively applied to the motor control device are shown.
In the simulation, the position / speed control unit 3, the current control unit 4, and the motor 5 in FIG. 1 were approximated by a first-order lag low-pass filter (cutoff frequency: 15 rad / s). Further, the load 6 is configured such that the transfer characteristic from the motor position xm to the load position y is such that a transfer function of a second-order lag system of resonance frequencies ω1 and ω2 as shown in Expression (4) is connected in series. In this case, the load 6 has two resonance modes of the resonance frequency ω1 and the resonance frequency ω2.

Here, d1: an attenuation coefficient of the resonance frequency ω1, d2: an attenuation coefficient of the resonance frequency ω2, and the respective values are the resonance frequency ω1 = 10 × 2π [rad / s] and ω2 = 10.5 × 2π [ rad / s], the damping coefficient d1 of the resonance frequency ω1 = 0.0, and the damping coefficient d2 of the resonance frequency ω1 = 0.4.

FIG. 5 is a simulation result when a normal notch filter is applied to a motor control device. The horizontal axis is the time axis, and the vertical axis is the position. Further, the normal notch filter corresponds to that constituted only by the first notch filter represented by the equation (1).
In this case, since the attenuation coefficient d1 of the resonance frequency ω1 is smaller than the attenuation coefficient d2 of the resonance frequency ω2, the normal notch filter is set to ωn = ω1, ζ1 = d1 so as to suppress the resonance of the resonance frequency ω1. To do.
In the figure, in order to speed up the position response of the motor position to the position command, the denominator-side attenuation coefficient ζ2 that is a notch filter parameter is gradually decreased from 1, the upper stage is ζ2 = 1, and the middle stage is ζ2 = 0.5. The lower part shows the waveform when ζ2 = 0.2.
As the denominator-side attenuation coefficient ζ2 is decreased, the position response becomes faster. However, since the transfer function of Equation (1) has a vibration pole, resonance at the resonance frequency ω2 is excited and large vibration is generated. It has occurred (see the lower figure). In the lower diagram, the motor position with respect to the position command substantially matches the target value after 0.2 seconds, but the subsequent vibration is large, and the influence of the vibration is large up to about 0.4 seconds.

FIG. 6 is a simulation result when the notch filter in the first embodiment of the present invention represented by the equation (3) is applied to the motor control device. The horizontal axis is the time axis, and the vertical axis is the position.
Here, the object to be controlled is expressed by equation (4), and the resonance frequency ω1 = 10 × 2π [rad / s], ω2 = 10.5 × 2π [rad / s], which are load parameters, and the attenuation coefficient of the resonance frequency ω1. It is assumed that d1 = 0.0 and the damping coefficient d2 = 0.4 of the resonance frequency ω1.
In this case, since the attenuation coefficient d1 of the resonance frequency ω1 is smaller than the attenuation coefficient d2 of the resonance frequency ω2, the notch filter has ωn = ω1, molecular side attenuation coefficients ζ1, ζ3 so as to suppress the resonance of the resonance frequency ω1. = D1 and the denominator-side damping coefficients ζ2, ζ4 = 1.0 so as not to have a vibration pole.
As the parameter K is increased, the position response becomes faster, and the transfer function of the equation (3) does not have a vibration pole, so that the resonance at the resonance frequency ω2 is not excited and a large vibration is generated. The time for the position response to converge is sufficiently fast (see the lower figure). In the lower diagram, the motor position relative to the position command matches the target value after 0.2 seconds, and the subsequent vibration is not so great.

As described above, according to the motor control apparatus in the first embodiment of the present invention, by adjusting the parameter K, the delay of the notch filter can be improved without having the vibration pole. With respect to a certain control target, it is possible to accelerate positioning response without exciting vibrations in the vicinity of the frequency set to the center frequency ωn in the notch filter.

FIG. 3 is a block diagram of a motor control device according to the second embodiment of the present invention. In the figure, the motor control device includes a command generation unit 1, a notch filter 2, a position / speed control unit 3, and a current control unit 4, and power for driving a motor 5 (control target 7) coupled with a load 6. Supply.
The motor control device of the present embodiment is different from the motor control device of the first embodiment in that the notch filter 2 is not the position command xr that is the output of the command generation unit 1 but the output of the position / speed control unit 3. This is a point that is applied to the torque command tref. Since the other components with the same reference numerals have the same operational effects, detailed description thereof is omitted.

In the simulation, the position / velocity control unit 3 in FIG. 3 uses position proportional control (proportional gain 100 [rad / s]) and speed proportional control (proportional gain 600 [rad / s]), and the current control unit 4 responds. Omitted as fast enough. Further, the load 6 is configured such that the transfer characteristic from the motor position xm to the load position y is represented by a second-order lag transfer function having a resonance frequency ω3 as shown in Expression (5).

ここで、負荷パラメータである共振周波数ω３＝１００×２π［ｒａｄ／ｓ］、共振周波数ω３の減衰係数ｄ３＝０．０とする。

Here, it is assumed that the resonance frequency ω3 = 100 × 2π [rad / s], which is the load parameter, and the attenuation coefficient d3 = 0.0 of the resonance frequency ω3.

FIG. 7 is a simulation result when the notch filter according to the second embodiment of the present invention is applied to a motor control device. The horizontal axis is the time axis, and the vertical axis is the position.
The upper diagram shows the case where the notch filter is not applied, the middle diagram shows the case where the normal notch filter constituted only by the first notch filter represented by the formula (1) is applied to the motor control device, and the lower diagram shows the present invention. This is when the notch filter in the second embodiment is applied to a motor control device.
In the figure, in the upper diagram, the control object 7 is a resonance system of 100 Hz, whereas the control gain of the position / velocity control unit 3 is high, so that the response indicating the motor position oscillates. In the middle diagram, a normal notch filter is used to respond stably without oscillation, but a large amount of vibration remains during positioning. This vibration does not stop even if each parameter of a normal notch filter is adjusted. In the lower diagram, the parameters of the notch filter in the second embodiment of the present invention are as follows. The resonance frequency ωn is 100 × 2π that is the same value as ω3, and the molecular side attenuation coefficients ζ1 and ζ3 that are notch filter parameters are the same values as d3. By setting to 0.0, denominator-side damping coefficient ζ4 = 0.16, and gain parameter K = 0.666, vibration during positioning is sufficiently small as compared with the case where a normal notch filter is applied. is made of.

As described above, the notch filter and the motor control apparatus including the notch filter according to the first and second embodiments of the present invention can adjust the numerator and denominator damping coefficients ζ 1 and ζ 2, while Since the notch filter has five parameters, numerator and denominator damping coefficients ζ1, ζ2, ζ3, ζ4, and gain K, and the characteristics of the notch filter can be designed in detail, vibration during positioning operation can be reduced. is there.

FIG. 4 is a block diagram of a motor control device according to the third embodiment of the present invention. In the figure, the motor control device includes a command generation unit 1, a notch filter 2, a position / speed control unit 3, and a current control unit 4, and power for driving a motor 5 (control target 7) coupled with a load 6. Supply.
The motor control device of this embodiment is different from the motor control device of the first embodiment in that the notch filter 2 is not the position command xr that is the output of the command generation unit 1 but the motor position that is the output of the position detection unit 8. It is a point that is applied to xm. Since the other components with the same reference numerals have the same operational effects, detailed description thereof is omitted.
Also in this case, as in the first or second embodiment, there is an effect of reducing vibration during positioning as compared with a normal notch filter.

Here, the input / output frequency characteristics of the notch filter according to the embodiment of the present invention and a normal notch filter are compared. Note that the normal notch filter corresponds to a configuration including only the first notch filter represented by the equation (1).
FIG. 8 is an input / output frequency characteristic diagram of the notch filter in the embodiment of the present invention. In the figure, the upper stage is gain characteristics, the lower stage is phase characteristics, the upper vertical axis is gain, the lower vertical axis is phase, and the horizontal axis is frequency. In the embodiment of the present invention, the notch filter is a solid line, and the normal notch filter is a broken line.
The notch filter in the embodiment of the present invention maintains the gain characteristic (−40 dB in the figure) of the center frequency (5 Hz in the figure) by adjusting only the gain K, and increases the gain characteristics other than the center frequency. It is possible to reduce the phase delay below the center frequency (shown arrow) (shown arrow).

The gain characteristics other than the center frequency in the notch filter can be improved without having a vibration pole, and the phase delay below the center frequency can be improved, so the notch can also be used when the controlled object has multiple resonances at close frequencies. A single-axis motor can be designed because the delay from the input signal by the notch filter can be reduced without exciting resonance other than the frequency set by the filter, and the filter characteristics can be designed in more detail than a normal notch filter. It can be applied not only to control devices but also to vibration suppression for industrial robots with multiple axes. In this case, it can be applied to a position command in the taught hand coordinate system, and can also be applied to each axis position command after being converted into a command for each axis. Furthermore, since this notch filter is not limited to motor control, it can also be applied to vibration suppression in plants, electrical circuits, signal processing, and the like.

DESCRIPTION OF SYMBOLS 1 Command generation part 2 Notch filter 3 Position / speed control part 4 Current control part 5 Motor 6 Load 7 Control object 8 Position detection part 20 Notch filter 21 Notch filter 1
22 Subtractor 23 Notch filter 2
24 gain multiplier 25 adder

Claims (4)

A notch filter that lowers the gain characteristic of a specific frequency in the input signal,
A first notch filter that inputs the input signal and outputs a first signal with a reduced gain characteristic of the specific frequency;
A subtractor for subtracting the input signal and the first signal;
A second notch filter that inputs an output signal of the subtractor and outputs a second signal having a reduced gain characteristic of the specific frequency;
A gain multiplier for multiplying the second signal by a gain;
An adder that adds the first signal and the output signal of the gain multiplier;
A notch filter that outputs an output signal of the adder with respect to the input signal. A command generator for generating and outputting a position command;
A control unit that calculates and outputs a power supply command so that the position command and the motor position detected by the position detector coincide with each other, and is coupled to the motor with the position detector and the motor. A motor control device for driving a control object composed of a load
With respect to the position command, comprising a notch filter that lowers the gain characteristic of the specific frequency in the position command and outputs it as a new position command,
A first notch filter that receives the position command and outputs a first signal with a reduced gain characteristic of the specific frequency;
A subtractor for subtracting the position command and the first signal;
A second notch filter that inputs an output signal of the subtractor and outputs a second signal having a reduced gain characteristic of the specific frequency;
A gain multiplier for multiplying the second signal by a gain;
An adder that adds the first signal and the output signal of the gain multiplier;
A motor control device that outputs an output signal of the adder as the new position command in response to the position command. A command generator for generating and outputting a position command;
A control unit that calculates and outputs a power supply command so that the position command and the motor position detected by the position detector coincide with each other, and is coupled to the motor with the position detector and the motor. A motor control device for driving a control object composed of a load
With respect to the motor position, a notch filter that lowers the gain characteristic of a specific frequency at the motor position and outputs it as a new motor position,
A first notch filter that inputs the motor position and outputs a first signal with a reduced gain characteristic of the specific frequency;
A subtractor for subtracting the motor position and the first signal;
A second notch filter that inputs an output signal of the subtractor and outputs a second signal having a reduced gain characteristic of the specific frequency;
A gain multiplier for multiplying the second signal by a gain;
An adder that adds the first signal and the output signal of the gain multiplier;
A motor control device that outputs an output signal of the adder as the new motor position with respect to the motor position. A command generator for generating and outputting a position command;
A position / speed control unit that calculates and outputs a torque command so that the position command and the motor position detected by the position detector coincide with each other, and includes the position detector based on the torque command. A motor control device for driving a controlled object composed of a motor and a load coupled to the motor,
With respect to the torque command, comprising a notch filter that lowers the gain characteristic of the specific frequency in the torque command and outputs it as a new torque command,
A first notch filter that receives the torque command and outputs a first signal with a reduced gain characteristic of the specific frequency;
A subtractor for subtracting the torque command and the first signal;
A second notch filter that inputs an output signal of the subtractor and outputs a second signal having a reduced gain characteristic of the specific frequency;
A gain multiplier for multiplying the second signal by a gain;
An adder that adds the first signal and the output signal of the gain multiplier;
A motor control device that outputs an output signal of the adder as the new torque command in response to the torque command.

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