JP2012019370A - Adaptive notch filter, and method of adjusting parameters of notch filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a notch filter automatically to minimize the oscillatory frequency components which are generated when the control band is widened.SOLUTION: The adaptive notch filter comprises a notch filter which minimizes the natural frequency component of an object to be controlled included in a signal which generates a control input to the object to be controlled where resonance may take place, and a parameter adjusting unit which adjusts parameters including the center frequency and notch width of the notch filter. The parameter adjusting unit selects the parameters of a notch filter to be adjusted according to the relationship of the oscillatory frequency components generated when the control band is widened and the center frequency of the notch filter.

Description

  The present invention relates to an adaptive notch filter with adjustable filter coefficients.

  For example, Patent Document 1 describes a motor control device in which a vibration extraction filter and a notch control unit are provided for each of a plurality of notch filters. The notch control unit controls the notch frequency of the notch filter so that the amplitude of the vibration component signal extracted by the vibration extraction filter decreases. In the vibration extraction filter, different frequency bands are set in correspondence with the notch filters. The plurality of notch filters, the vibration extraction filter, and the notch control unit operate in parallel.

JP 2009-296746 A

  By the way, for example, in order to increase the responsiveness of the control system, it may be desired to extend the control band to a higher band. It is practically required to effectively suppress a new vibration frequency component generated when the control band is expanded.

  One of the objects of the present invention is to automatically adjust the notch filter so as to suppress the vibration frequency component generated when the control band is expanded.

  An adaptive notch filter according to an aspect of the present invention includes a notch filter for suppressing a natural frequency component of a control target included in a signal for generating a control input to the control target in which resonance can occur, and the notch filter A parameter adjustment unit for adjusting parameters including the center frequency and the notch width of The parameter adjustment unit selects a parameter of the notch filter to be adjusted according to a relationship between a vibration frequency component generated when the control band of the control target is expanded and a center frequency of the notch filter.

  According to this aspect, the parameter of the notch filter to be adjusted is selected according to the relationship between the vibration frequency component generated when the control band to be controlled is expanded and the center frequency of the notch filter. Thereby, it is possible to effectively adjust the notch filter while suppressing the influence on the extended control band.

  Another aspect of the present invention is a parameter adjustment method for a notch filter. This method estimates the vibration frequency component generated when the control band of the control object to which the notch filter is applied is expanded, and should be adjusted according to the relationship between the vibration frequency component and the center frequency of the notch filter. Selecting a parameter of the notch filter and adjusting the parameter of the selected notch filter so as to suppress the vibration frequency component.

  According to the present invention, the notch filter can be automatically adjusted so as to suppress the vibration frequency component generated when the control band is expanded.

It is a block diagram which shows the structure of the adaptive notch filter which concerns on one Embodiment of this invention. It is a figure which shows the example of the frequency characteristic of the notch filter which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the parameter adjustment part which concerns on one Embodiment of this invention. It is a figure which shows the example of the frequency characteristic of the peak filter which concerns on one Embodiment of this invention. It is a figure which shows the average value of the center frequency correction amount which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the pre filter which concerns on one Embodiment of this invention. It is a block diagram which shows the system configuration | structure of the control apparatus which concerns on one Embodiment of this invention. It is a flowchart for demonstrating the adjustment process of the center frequency which concerns on one Embodiment of this invention. It is a figure which shows typically the overlap of the notch filter which concerns on one Embodiment of this invention. It is a flowchart for demonstrating the adjustment process of the notch filter which concerns on one Embodiment of this invention. It is a figure which shows typically the overlap of the notch filter which concerns on one Embodiment of this invention. It is a flowchart for demonstrating the adjustment process of the notch filter which concerns on one Embodiment of this invention. It is a figure for demonstrating typically an example of the adjustment process of the notch filter shown in FIG.

  FIG. 1 is a block diagram showing a configuration of an adaptive notch filter 10 according to an embodiment of the present invention. The adaptive notch filter 10 includes a notch filter unit 12, a parameter adjustment unit AF, a prefilter PF, and a notch filter control unit EVL. The parameter adjustment unit AF is provided to adjust the parameters of the notch filter unit 12. The pre-filter PF is a filter for preprocessing an input signal input to the parameter adjustment unit AF. The notch filter control unit EVL switches a switch SW0 for selecting a notch filter whose parameter is to be adjusted by the parameter adjustment unit AF. The notch filter control unit EVL switches the switch SW0 based on the input signal u to the parameter adjustment unit AF.

The notch filter unit 12 includes at least two notch filters connected in series. In the example shown in the figure, two notch filters MNF1 and MNF2 are arranged in series. Third to nth notch filters MNF3 to MNFn may be further added in series. The notch filter is a known filter having a frequency characteristic shown in FIG. 2, for example. Notch filter at the center frequency omega ₀ has a minimum value of the amplitude gain, to suppress the center frequency omega ₀ and frequency components in the vicinity of the input signal and outputs an output signal. The center frequencies of the plurality of notch filters are set to different values, and the center frequency ω ₁₀ of the first notch filter MNF1 and the center frequency ω ₂₀ of the second notch filter MNF2 are also different in the illustrated example.

  Rather than associating one notch filter with each divided individual frequency band, the center frequency of each notch filter is allowed to be set to a common frequency band. Thereby, it becomes possible to adjust each notch filter flexibly corresponding to a plurality of resonance frequencies. This common band is, for example, a frequency band excluding the control band. Alternatively, the common band is a band higher than a predetermined frequency. This predetermined frequency is, for example, a frequency equal to or higher than the upper limit of the control band. Note that the common band is not limited to one. A plurality of frequency bands may be set, and each frequency band may be allowed to include the center frequencies of the plurality of notch filters.

The input signal τ ₁ to the notch filter unit 12 is, for example, a control command to a control target to which the notch filter unit 12 is applied. The input signal τ ₁ may be generated based on an error between a detection value of an output from the control target and a desired target command value. The input signal τ ₁ may be a target command. The input signal τ ₁ may be an observation amount (for example, position, speed, acceleration, etc.) from the control target. The output signal τ ₂ may be used as a detection value of the output from the control target. The output signal τ ₂ of the notch filter unit 12 may be used as a control input to the control target. The filter coefficient of each notch filter is adjusted so as to remove the natural frequency component to be controlled from the input signal τ ₁ . For this purpose, the center frequency of each notch filter is adjusted to match any natural frequency component of the control target.

  Each notch filter is provided so as to be switchable between an effective state in which the filter function is enabled and an inactive state in which the filter function is disabled. The first notch filter MNF1 is provided with a first notch filter switch SW1 for switching between the valid state and the invalid state. Similarly, the second notch filter MNF2 includes a second notch filter switch SW2. Is provided. The first notch filter changeover switch SW1 and the second notch filter changeover switch SW2 are provided in the subsequent stage of the first notch filter MNF1 and the second notch filter MNF2, respectively. Each notch filter is switched between a valid state and an invalid state by a notch filter control unit EVL, for example.

  The parameter adjustment unit AF is provided in common to the plurality of notch filters of the notch filter unit 12 and adjusts parameters of at least one selected notch filter. The parameter adjustment unit AF adjusts parameters including at least the center frequency. In the illustrated embodiment, the parameter adjustment unit AF performs adjustment of one of the first notch filter MNF1 and the second notch filter MNF2. An adjustment target selection switch SW0 is provided in the adaptive notch filter 10 in order to select a notch filter to be adjusted. Since the parameters of the selected notch filter are adjusted, the amount of calculation can be reduced as compared with the case where a plurality of notch frequencies are controlled in parallel. In addition, the parameter adjustment part AF may be provided for every notch filter, and the adaptive notch filter 10 may be comprised so that each parameter adjustment part AF may adjust the corresponding notch filter in parallel.

  The parameter adjustment unit AF corrects the filter coefficient of the notch filter unit 12 based on the reference signal d. In the illustrated example, the parameter adjustment unit AF corrects the filter coefficient of the notch filter unit 12 based on the input signal u obtained by processing the reference signal d with the pre-filter PF. The reference signal d may be a control command to a control target to which the notch filter unit 12 is applied, or may be an observation amount from the control target. The parameter adjustment unit AF may use any signal that can extract the vibration component to be controlled as the reference signal d.

FIG. 3 is a block diagram showing the configuration of the parameter adjustment unit AF according to one embodiment of the present invention. The parameter adjustment unit AF includes a phase difference filter 14 and a correction calculation unit 16. The phase difference filter 14 receives the output signal u of the prefilter PF and outputs a phase difference filter output signal p. Here, the phase difference filter 14 refers to a filter that gives a phase shift according to a frequency component. The phase characteristic of the phase difference filter 14 is that the phase shift of the output signal p is changed from the first phase shift to the second as the frequency of the input signal u increases from the lower limit frequency to the upper limit frequency of the local frequency region including the center frequency ω ₀ . Change monotonically to phase shift. In the lower frequency region than the lower limit frequency, the phase shift is substantially equal to the first phase shift, and in the higher frequency region than the upper limit frequency, the phase shift is substantially equal to the second phase shift.

When the correction of the center frequency ω ₀ is performed using the center frequency correction amount Δω ₀ described in detail below, the phase characteristic of the phase difference filter 14 is substantially lower in the lower frequency region than the lower limit frequency of the local frequency region. It is preferable that a phase delay of 0 degree is given to (i.e., the phase is not substantially delayed), and a phase delay of 180 degrees is given in a frequency region higher than the upper limit frequency. Regarding the phase characteristics of the phase difference filter 14, the phase delay of the output signal p increases from 0 degree to 180 degrees as the frequency of the input signal u increases from the lower limit frequency to the upper limit frequency in the local frequency region. When the frequency component of the input signal u is equal to the center frequency ω ₀ , the phase delay of the output signal p is set to be equal to 90 degrees.

In a preferred embodiment, the phase difference filter 14 may be a peak filter having a frequency amplitude characteristic having a gain peak at the center frequency ω ₀ in addition to the above phase characteristic. An example of the frequency amplitude characteristic and frequency phase characteristic of the peak filter is shown in FIG. As shown in frequency-phase characteristic of FIG. 4, the phase contrast filter 14, the center frequency omega ₀ takes a reference phase delay (e.g. 90 degrees) at the center frequency omega ₀ sufficiently small phase lag than the reference phase delay in the neighborhood of It has a phase characteristic that changes from (for example, 0 degrees) to a sufficiently large phase delay (for example, 180 degrees). When the peak filter is a digital filter, the transfer function _GP of the peak filter is expressed by the following equation. Here, k is a parameter that determines the center frequency ω ₀ , and l _p is a parameter that determines the attenuation of the peak.

The correction calculation unit 16 corrects the filter coefficient of the notch filter selected by the adjustment target selection switch SW0 based on the phase difference filter input signal u and the phase difference filter output signal p. The correction calculation unit 16 corrects the filter coefficient of the phase difference filter 14 based on the phase difference filter input signal u and the phase difference filter output signal p. The correction calculation unit 16 updates the filter coefficient at the time point n of the notch filter and the phase difference filter 14 to the filter coefficient at the time point n + 1 based on the input signal u and the output signal p. For example, the correction calculation unit 16 updates the center frequency ω ₀ to the value ω ₀ [n] at the time point n to the value ω ₀ [n + 1] at the time point n + 1 by the following equation. That is, the correction calculation unit 16 obtains the updated value ω ₀ [n + 1] by adding the correction amount Δω ₀ to the current value ω ₀ [n] of the center frequency ω ₀ .

The second term on the right side of Equation 1 is the correction amount Δω ₀ of the center frequency ω ₀ . Here, u [n] and p [n] denote the input signal u and the output signal p of the phase difference filter at time n, respectively. Φ _p [n] is a correction coefficient at time n. Although this correction coefficient will be described later, it is a correction coefficient for reducing the influence of the amplitude α of the input signal u. The correction coefficient Φ _p [n] is, for example, a smoothed square of the phase difference filter output signal p [n]. Since the output signal p [n] is a signal including a vibration component, it may take 0 or a value close to 0. Therefore, in order to avoid that the correction coefficient Φ _p [n] is 0 or a value close to 0 and the center frequency correction amount Δω ₀ is excessive, it is preferable to perform a smoothing process. The smoothing process may be performed by, for example, a low-pass filter. The correction coefficient may be a smoothed version of the square of the phase difference filter input signal u, or may be the square root of the square of the product pu of the input signal u and the output signal p. μ is a correction gain for adjusting the correction amount Δω.

FIG. 5 is a diagram showing an average value E [Δω ₀ ] of the center frequency correction amount when a peak filter is used as the phase difference filter 14. As shown in FIG. 5, the correction amount average value E [Δω ₀ ] is not only in the vicinity of the center frequency ω ₀ but also in a wide range of frequencies from the vicinity of zero to the vicinity of the Nyquist frequency ω _nyq (1/2 of the sampling frequency). In the region, it can be seen that there is a linear change with respect to the deviation between the center frequency ω ₀ and the input frequency ω. That is, in the band below the Nyquist frequency ω _nyq, the average value E [Δω ₀ ] of the center frequency correction amount is substantially proportional to the deviation between the center frequency ω ₀ and the input frequency ω.

Therefore, the correction amount Δω ₀ corresponding to the deviation between the center frequency ω ₀ and the input frequency ω can be obtained. That is, the correction amount Δω ₀ at the time of update increases as the notch center frequency ω ₀ is separated from the frequency ω to be suppressed by the adaptive notch filter 10. Therefore, the center frequency ω ₀ can be brought close to the frequency ω of the input signal u with a small number of update processing iterations. Further, the correction amount Δω ₀ decreases as the center frequency ω ₀ approaches the frequency ω to be suppressed. Therefore, it is possible to prevent the center frequency omega ₀ varies vibrationally every update the center frequency omega ₀ in the vicinity of the frequency omega of the input signal u. The center frequency ω ₀ can be quickly matched with the frequency ω of the input signal u.

  FIG. 6 is a block diagram showing the configuration of the pre-filter PF according to one embodiment of the present invention. The pre-filter PF includes a plurality of band rejection filters arranged in series corresponding to each of the plurality of notch filters of the notch filter unit 12. Each band stop filter has a stop band that includes the center frequency of the corresponding notch filter. The output of the band rejection filter at the final stage becomes the input signal u to the parameter adjustment unit AF.

  During the adjustment process of the selected notch filter, the corresponding band rejection filter is set to an invalid state. When the adjustment process of the selected notch filter is completed and the notch filter is in the valid state, the band rejection filter is also switched to the valid state. For example, each band rejection filter is switched between a valid state and an invalid state by the notch filter control unit EVL. The parameter adjustment unit AF adjusts the corresponding band rejection filter based on the adjusted parameter of the selected notch filter.

  The band rejection filter is a notch filter in this embodiment. Therefore, the pre-filter PF includes at least two notch filters connected in series. In the illustrated example, a first pre-notch filter PNF1 and a second pre-notch filter PNF2 are arranged in series corresponding to the first notch filter MNF1 and the second notch filter MNF2. When the third to n-th notch filters MNF3 to MNFn are provided, the third to n-th pre-notch filters PNF3 to PNFn are similarly added to the pre-filter PF.

  The center frequencies of the pre-notch filters PNF1 and PNF2 are set to values equal to the center frequencies of the corresponding notch filters MNF1 and MNF2. Other parameters (for example, the width and depth of the notches) of the pre-notch filters PNF1 and PNF2 may be set to the same value as the corresponding notch filters MNF1 and MNF2, or may be set to different values. For example, the Q value that is a parameter representing the width of the pre-notch filters PNF1 and PNF2 may be set to 0.5 to 1, and the depth may be set to −∞ dB. On the other hand, the Q values of the notch filters MNF1 and MNF2 may be set to 1 and the depth may be set to −∞ dB.

  For each band rejection filter, it is possible to switch between an effective state in which the filter function is valid and an invalid state in which the filter function is invalid. The first pre-notch filter PNF1 is provided with a first pre-notch filter switch SW11 for switching between the valid state and the invalid state, and the second pre-notch filter PNF2 is similarly provided with the second pre-notch filter PNF2. A changeover switch SW12 is provided. The first pre-notch filter changeover switch SW11 and the second pre-notch filter changeover switch SW12 are provided at the subsequent stage of the first pre-notch filter PNF1 and the second pre-notch filter PNF2, respectively. Each pre-notch filter is switched between a valid state and an invalid state by, for example, a notch filter control unit EVL.

  The prefilter PF includes a high pass filter HPF. The high-pass filter HPF is provided in front of the first pre-notch filter PNF1, processes the input signal d to the pre-filter PF, and applies it to the first pre-notch filter PNF1. The high pass filter HPF uses the control band as a limited band. That is, the high-pass filter HPF uses a band higher than the control band as the pass band. Alternatively, the high-pass filter HPF sets a band that is higher than the control band by a predetermined amount as a limited band. That is, the high pass filter HPF sets a band higher than the control band by a predetermined amount as the pass band.

  The notch filter control unit EVL sequentially inputs the notch filter of the notch filter unit 12 into the control system according to the vibration level of the input signal u. That is, when it is determined that the vibration level is smaller than the predetermined threshold value, all the notch filters are set in an invalid state. When the vibration of the signal u exceeds the vibration level threshold, the first notch filter MNF1 is switched to the valid state. The first notch filter MNF1 is adjusted by the parameter adjustment unit AF. If the vibration of the signal u still exceeds the vibration level threshold after the adjustment of the first notch filter MNF1 is completed, the second notch filter MNF2 is switched to the valid state and adjusted by the parameter adjustment unit AF. Similarly, after the adjustment of the second notch filter MNF2 is completed, the third notch filter MNF3 is switched to the valid state when the vibration of the signal u still exceeds the vibration level threshold value.

  In one embodiment, the notch filter control unit EVL may determine the vibration level using the residual vibration of the command response. For example, a predetermined time after the commanded acceleration becomes zero may be defined as an evaluation section, and the integral value of the absolute value of the evaluation target signal in the evaluation section may be defined as the vibration level. Alternatively, the notch filter control unit EVL may evaluate the vibration level based on the signal v obtained by applying the low-pass filter LPF to the square or absolute value of the input signal u. This low-pass filter LPF preferably has a control band as a pass band. The notch filter control unit EVL may evaluate the vibration level by other known appropriate methods. For example, the notch filter control unit EVL may determine the vibration level based on whether or not the amplitude of a specific frequency component exceeds a predetermined value.

  FIG. 7 is a block diagram showing a system configuration of the control device 100 according to an embodiment of the present invention. The control device 100 includes the adaptive notch filter 10 described above, and is configured to suppress resonance of a control target. The actuator 20 drives the load 22. The actuator 20 is, for example, a motor incorporated in a device in which control characteristics may be limited due to resonance of an industrial robot, an injection molding machine, a construction machine, a precision positioning stage, or the like. The detector 24 measures the output (for example, control amount ω) of the actuator 20. For example, the detection speed ω of the motor is measured. The parameter adjustment unit AF uses the detection signal ω of the detector 24 as the reference signal d, and corrects the coefficient of the notch filter.

A command generation unit (not shown) of the control device 100 determines a command value r. The controller VC outputs a command τ ₁ so that the control amount ω matches the command value r. The notch filter unit 12 removes the frequency component of the center frequency of the notch filter in the effective state from the command signal τ ₁ and outputs a new command signal τ ₂ . The center frequency corresponds to the frequency component of the natural frequency ω _n of the system including the actuator 20 and the load 22. When there are a plurality of natural frequency components, a plurality of notch filters are enabled, and each natural frequency component is suppressed. Actuator control unit TC controls the actuator 20 based on the command signal tau _2.

  In the adaptive notch filter 10 shown in FIGS. 1 and 7, when the center frequency of the notch filter selected and adjusted from the notch filter unit 12 is adjusted to a predetermined band including the center frequency of another notch filter, The center frequency of the notch filter may be changed. When the center frequency of the selected notch filter is adjusted to the vicinity of the center frequency of the other notch filter, the parameter adjusting unit AF adjusts the center frequency of the other notch filter to be closer to the center frequency of the selected notch filter. Preferably, the parameter adjusting unit AF matches the center frequency of the other notch filter with the center frequency of the selected notch filter, and switches the selected notch filter to an invalid state. In this way, the parameters of the other notch filters are changed based on the adjustment result of one notch filter.

  For example, when the center frequency of the second notch filter MNF2 is adjusted to the vicinity of the center frequency of the first notch filter MNF1, the center frequency of the first notch filter MNF1 is changed. The center frequency of the first notch filter MNF1 is modified to approach the center frequency of the second notch filter MNF2. Preferably, the center frequency of the first notch filter MNF1 is modified to match the center frequency of the second notch filter MNF2. In this case, the second notch filter MNF2 is switched to an invalid state. Note that the width and depth of the first notch filter MNF1 and the second notch filter MNF2 may be adjusted together with the correction of the center frequency or instead of the correction of the center frequency, as will be described later.

  FIG. 8 is a flowchart for explaining a center frequency adjustment process according to an embodiment of the present invention. The example shown in FIG. 8 is based on the premise that the first notch filter MNF1 is in an effective state and the adjustment of the center frequency is completed. Note that the center frequency of the first notch filter MNF1 is adjusted to match the resonance frequency component having the maximum gain in a band higher than the control band.

  As shown in FIG. 8, the notch filter control unit EVL determines whether or not the vibration level exceeds a threshold value (S10). When it is determined that the vibration level is within the threshold (N in S10), the notch filter control unit EVL ends this process and waits for the next process. The low vibration level means that the first notch filter MNF1 is appropriately set and vibration is effectively suppressed.

When it is determined that the vibration level exceeds the threshold value (Y in S10), the notch filter control unit EVL switches and adjusts the second notch filter changeover switch SW2 to enable the second notch filter MNF2. The object selection switch SW0 is switched from the neutral state to the second notch filter MNF2. The notch filter control unit EVL switches the second pre-notch filter switch SW12 so that the second pre-notch filter PNF2 is in an invalid state. By disabling the second pre-notch filter PNF2, the frequency component suppressed by the second notch filter MNF2 to be adjusted is input to the parameter adjustment unit AF. Thus, the adjustment of the center frequency ω ₂₀ of the second notch filter MNF2 is started (S12). At this time, the first notch filter MNF1 and the first pre-notch filter PNF1 are continuously enabled.

  At this time, if there are third to n-th pre-notch filters PNF3 to PNFn corresponding to the third to n-th notch filters MNF3 to MNFn, the pre-corresponding to the notch filter that is in an invalid state in the notch filter unit 12 is provided. The notch filter is also disabled. The frequency component suppressed by the second notch filter MNF2 to be adjusted by disabling the pre-notch filter corresponding to the notch filter that is in an invalid state in the second pre-notch filter PNF2 and the notch filter unit 12. Is input to the parameter adjustment unit AF.

The center frequency ω ₂₀ of the second notch filter MNF2 is adjusted so as not to be included in the vicinity of the center frequency ω ₁₀ of the first notch filter MNF1 (for example, a range of 0.5 to 2 times ω ₁₀ ). For this purpose, the first pre-notch filter PNF1 removes the frequency component suppressed by the first notch filter MNF1 from the reference signal d. Further, for example, the initial value for setting the center frequency ω ₂₀ of the second notch filter MNF2 is set to a value separated from the center frequency ω ₁₀ of the first notch filter MNF1 (for example, a value exceeding twice ω ₁₀ ). . In this way, the center frequency ω ₂₀ of the second notch filter MNF2 is matched with the resonance frequency component having the maximum gain in the band higher than the control band while avoiding the vicinity of the center frequency ω ₁₀ of the first notch filter MNF1. It becomes possible to adjust to. In the above update processing method, for example, it is considered that the adjustment of the center frequency is completed when Δω ₀ becomes a sufficiently small reference value or less.

Parameter adjusting portion AF is set to a value equal to the center frequency of the second pre-notch filter PNF2 the center frequency omega ₂₀ of the second notch filter MNF2 (S14). The notch filter control unit EVL switches the second pre-notch filter selector switch SW12 so as to make the second pre-notch filter PNF2 effective.

  At this time, the notch filter control unit EVL may test the vibration level before setting the second pre-notch filter PNF2. That is, the notch filter control unit EVL determines whether or not the vibration level after adjustment has increased compared to that before the adjustment of the second notch filter MNF2, and when the vibration level increases, the second notch filter MNF2 is disabled. You may make it return to. This is because when the vibration level increases, some abnormality is assumed in the setting of the notch filter.

The notch filter control unit EVL determines whether or not the center frequency ω ₂₀ of the second notch filter MNF2 is included in a predetermined band including the center frequency ω ₁₀ of the first notch filter MNF1 (S16). This predetermined band is, for example, a range for determining whether or not it is in the vicinity of the center frequency ω ₁₀ of the first notch filter MNF1, for example, a range of 85% to 115%. Alternatively, it may preferably be in the range of 95% to 115% of the center frequency ω ₁₀ of the first notch filter MNF1. By narrowing the low band side of the center frequency ω _{10 in} the predetermined band from the high band side, the influence of the phase delay due to the notch filter can be mitigated.

When the center frequency ω ₂₀ of the second notch filter MNF2 is not included in the predetermined band (N in S16), the notch filter control unit EVL ends the process. Both notch filters are enabled. It is considered that the center frequency ω ₂₀ of the second notch filter MNF2 is sufficiently separated from the center frequency ω ₁₀ of the first notch filter MNF1, and each of the two notch filters is appropriately set to a different resonance frequency component.

On the other hand, when the center frequency ω ₂₀ of the second notch filter MNF2 is included in the predetermined band (Y in S16), the notch filter control unit EVL switches the second notch filter MNF2 to the invalid state and also sets the first notch filter The center frequency ω ₁₀ of the MNF 1 is corrected so as to coincide with the center frequency ω ₂₀ of the second notch filter MNF 2 (S18). Since the center frequency ω ₁₀ of the first notch filter MNF1 is slightly different from the frequency component that should be suppressed for some reason, the center frequency ω ₂₀ of the second notch filter MNF2 is equal to the center frequency ω ₁₀ of the first notch filter MNF1. This is because it is considered to be set in the vicinity.

The notch filter control unit EVL determines again whether or not the vibration level exceeds the threshold value (S10), and if the vibration level is within the threshold value (N of S10), the first notch filter. Only MNF1 is enabled. When it is determined that the vibration level exceeds the threshold value (Y in S10), the notch filter control unit EVL adjusts the second notch filter MNF2 again. When the adjustment of the second notch filter MNF2 is performed again, a predetermined band for determining whether or not the center frequency ω ₂₀ of the second notch filter MNF2 is included in a predetermined band including the center frequency ω ₁₀ of the first notch filter MNF1. A process of determining whether the center frequency ω ₂₀ of the second notch filter MNF2 is included in a predetermined band including the center frequency ω ₁₀ of the first notch filter MNF1 may be made narrower than at the time of the first adjustment. It may be omitted.

  The example shown in FIG. 8 starts when only the first notch filter MNF1 is in an effective state, but the first notch filter MNF1 and the second notch filter MNF2 are in an effective state and the adjustment of the center frequency is completed. The same is true in the state where In this case, when it is determined that the vibration level exceeds the threshold value (Y in S10), the notch filter control unit EVL starts to adjust the third notch filter MNF3.

  In this way, according to the present embodiment, notch filters are sequentially added according to the vibration level, and each notch filter suppresses the resonance frequency. A plurality of notch filters are automatically adjusted to suppress a plurality of resonances. Since the parameter adjustment unit adjusts the center frequency of the selected notch filter, it is not necessary to adjust all the notch filters in parallel, and the amount of calculation can be reduced. In addition, the notch filter unit 12 and the pre-filter PF have a corresponding series filter configuration, and the pre-notch filter corresponding to the parameter adjustment target notch filter is temporarily disabled during the adjustment process. The pre-filter corresponding to the notch filter that is disabled in the notch filter unit 12 is also temporarily disabled during the adjustment process. As a result, the frequency band to be suppressed by the notch filter to be adjusted can be input to the parameter adjustment unit AF with a simple configuration.

  Further, another notch filter is adjusted based on the adjustment result of one notch filter. A notch filter is added at least temporarily, and the parameters of the additional filter are adjusted. The center frequency of each notch filter is allowed to be set to a common frequency band. If the center frequency of the additional filter is far from the other notch filter and suppresses the resonant frequency component that is separate from the resonant frequency component suppressed by the other notch filter, the additional filter will continue to be used. Is done. If the additional filter cannot be considered to suppress a separate resonant frequency component, the existing notch filter is readjusted and the additional filter is returned to the disabled state. In this way, it is possible to adjust a plurality of notch filters flexibly in accordance with a plurality of resonance frequencies, as compared with the case where one notch filter is associated with each divided frequency band.

  Further, in one embodiment of the present invention, when the center frequency of one of the first notch filter MNF1 and the second notch filter MNF2 is adjusted, the first notch filter MNF1 and the notch filter MNF1 The notch width or the notch depth of at least one of the second notch filters MNF2 may be adjusted.

  The parameter adjusting unit AF narrows the notch width of at least one of the first notch filter MNF1 and the second notch filter MNF2 so as to reduce the overlap of the amplitude characteristic and the phase characteristic of the first notch filter MNF1 and the second notch filter MNF2. May be. Alternatively, the parameter adjusting unit AF reduces the amplitude characteristic and phase characteristic of the first notch filter MNF1 and the second notch filter MNF2 by reducing the notch depth of at least one of the first notch filter MNF1 and the second notch filter MNF2. The overlap may be reduced. The parameter adjustment unit AF may preferentially adjust the notch width, and may start adjusting the notch depth when the limit of the preset adjustment range of the notch width is reached.

  FIG. 9 is a diagram schematically illustrating the overlap of notch filters according to an embodiment of the present invention. FIG. 9 shows the frequency amplitude characteristics of the first notch filter MNF1 and the second notch filter MNF2. As an example, the case where the second notch filter MNF2 is on the lower band side than the first notch filter MNF1 is shown, but conversely the case where the first notch filter MNF1 is located on the lower band side than the second notch filter MNF2. If the first notch filter MNF1 and the second notch filter MNF2 are replaced, the following description is similarly established.

Since the initial values of the width and depth of the first notch filter MNF1 and the second notch filter MNF2 are both set to be equal, the first notch filter MNF1 and the second notch filter MNF2 are the same as shown in the figure. It has a chevron-shaped amplitude characteristic. As a parameter representing the notch width, for example, a bandwidth whose gain is smaller than adB can be used. This bandwidth is, for example, the half width ω _i2 −ω _i1 , in which case adB is approximately −3 dB. A Q value may be used as a parameter representing the notch width. The Q value of the first notch filter MNF1 is Q1 = ω ₁₀ / (ω ₁₂ −ω ₁₁ ), and the Q value of the second notch filter MNF2 is Q2 = ω ₂₀ / (ω ₂₂ −ω ₂₁ ). The larger the Q value, the narrower the notch width. In this embodiment, the initial value of the Q value is set to 1, and the notch filter is relatively wide.

FIG. 9 shows a frequency ω ₁₁ at which the amplitude gain is 1 / √2 (about −3 dB) on the lower band side (left side in the figure) than the center frequency ω ₁₀ of the first notch filter MNF1, and the second notch filter MNF2. This shows a case where the frequency ω ₂₂ at which the amplitude gain is 1 / √2 (about −3 dB) on the higher band side (right side in the figure) than the center frequency ω ₂₀ is equal. This state can be used as one of criteria for determining the degree of overlap between the two notch filters. That is, when ω ₁₁ is larger than ω ₂₂ , it is determined that the degree of overlap between the two notch filters is small, and when ω ₁₁ is smaller than ω ₂₂ , it is determined that the degree of overlap between the two notch filters is large. Also good.

  Further, for example, a depth parameter D may be used as a parameter representing the depth of the notch filter. As shown in the figure, 20 times the logarithm of the depth parameter D (20 log D) corresponds to the gain value at the center frequency. The greater the depth parameter D, the shallower the notch depth. In this embodiment, the initial value of the depth parameter D is set to 0, and the notch filter is set deep.

As shown in the drawing, in the band in the vicinity of the frequency ω ₁₁ (= ω ₂₂ ), the gain is suppressed by both the first notch filter MNF1 and the second notch filter MNF2. However, the resonance frequency component to be suppressed should substantially coincide with the center frequencies ω ₁₀ and ω ₂₀ of each notch filter, and is somewhat away from the frequency ω ₁₁ (= ω ₂₂ ). The band near the frequency ω ₁₁ (= ω ₂₂ ) does not necessarily need to be suppressed. By reducing the overlap between the first notch filter MNF1 and the second notch filter MNF2 and separating the two filters, the resonance frequency component is suppressed to a pinpoint while avoiding suppressing an unnecessarily wide band signal. Is possible.

  Further, when a new vibration frequency component becomes apparent as a result of reducing the overlap between the two notch filters, an additional notch filter can be set to suppress the vibration component. When this vibration component is the third resonance frequency component, a dedicated notch filter is used rather than suppressing at the so-called portion of the existing notch filter for suppressing the first or second resonance frequency component. It is preferable to newly assign and suppress.

  FIG. 10 is a flowchart for explaining notch filter adjustment processing according to an embodiment of the present invention. The process shown in FIG. 10 is executed when both the first notch filter MNF1 and the second notch filter MNF2 are in an effective state. For example, when the second notch filter MNF2 is set to be effective in the embodiment shown in FIG. 8 (N in S16 of FIG. 8), it may be executed subsequently.

If the amplitude gain at the frequency specified as the control band is limited by any notch filter, the amplitude gain at the frequency specified as the control band is limited by the notch filter prior to the adjustment process of FIG. Pre-processing may be performed to prevent this from happening. For example, the frequency ω _i1 at which the amplitude gain is 1 / √2 on the lower band side than the center frequency ω _i0 of the i-th notch filter that has the lowest center frequency is smaller than the frequency specified as the control band. In this case, the Q value of the i-th notch filter is adjusted so that ω _i1 is equal to the frequency designated as the control band.

  In the process shown in FIG. 10, the parameter adjustment unit AF determines whether or not the degree of overlap between the first notch filter MNF1 and the second notch filter MNF2 exceeds a preset reference (S20). In this embodiment, when the half widths of the amplitude characteristics of the first notch filter MNF1 and the second notch filter MNF2 are overlapped, it is determined that the overlap is large, and when the half widths are not overlapped, it is determined that the overlap is small. To do.

Specifically, as shown in FIG. 9, when the center frequency ω ₁₀ of the first notch filter MNF1 is larger than the center frequency ω ₂₀ of the second notch filter MNF2, the frequency ω described with reference to FIG. ₁₁ and the frequency ω ₂₂ are used to determine whether the two filters overlap. That is, when the frequency ω ₁₁ is smaller than the frequency ω _22, it is determined that the two filters overlap each other, and when the frequency ω ₁₁ is equal to or higher than the frequency ω _22, it is determined that they do not overlap. On the other hand, when the center frequency ω ₁₀ of the first notch filter MNF1 is smaller than the center frequency ω ₂₀ of the second notch filter MNF2, the degree of overlap between the two filters due to the magnitude relationship between the frequency ω ₁₂ and the frequency ω _21. Is determined. That is, when the frequency ω ₁₂ is higher than the frequency ω _21, it is determined that the two filters overlap each other, and when the frequency ω ₁₂ is equal to or lower than the frequency ω _21, it is determined that they do not overlap.

  When it is determined that the overlap between the first notch filter MNF1 and the second notch filter MNF2 is within the reference and the overlap is small (N in S20), the parameter adjustment unit AF performs the first notch filter MNF1 and the second notch filter MNF1. The notch width or notch depth of the notch filter MNF2 is not adjusted. In this case, the notch width and the notch depth of the first notch filter MNF1 and the second notch filter MNF2 are left at the initial values.

  The notch width or the notch depth may be adjusted even when the overlapping degree of the two filters is within the reference. You may adjust so that an overlap state may be made small or enlarged. In this case, as will be described later, the notch width or the notch depth may be adjusted while monitoring the vibration level. When the vibration level is increased by the adjustment, the additional notch filter may be switched to an effective state in order to suppress the exposed vibration frequency component.

  On the other hand, when the overlap determination condition is satisfied, that is, when it is determined that the degree of overlap between the first notch filter MNF1 and the second notch filter MNF2 is large (Y in S20), the parameter adjustment unit AF performs vibration. It is determined whether or not the level exceeds a threshold value (S22). The notch filter control unit EVL may determine whether or not the vibration level exceeds a threshold value. It is preferable to determine whether or not the vibration level of the response to the command to the controlled object exceeds a threshold value. This determination threshold value is a threshold value for determining whether or not the vibration to be suppressed is sufficiently small, similar to the vibration level threshold value in the above-described embodiment. For example, this threshold value is empirical or experimental. Can be set as appropriate.

  When it is determined that the vibration level is within the threshold value (N in S22), the parameter adjustment unit AF uniformly adjusts the notch widths of the first notch filter MNF1 and the second notch filter MNF2 (S24). . The parameter adjustment unit AF increases the Q value of the first notch filter MNF1 and the second notch filter MNF2 from the initial value to a common correction value. This makes the two notch filters similarly narrow.

  The parameter adjustment unit AF adjusts the notch width until a preset limit value of the adjustment range is reached or until the overlap determination condition of the two notch filters is not satisfied. When the Q value is used as a parameter representing the notch width, when the upper limit value of the adjustment range of the Q value is reached, the adjustment of the Q value is terminated at the upper limit value, and the adjustment of the notch depth is started. Also good. By adjusting the depth parameter D to be large in common for the first notch filter MNF1 and the second notch filter MNF2, the notch depths of the first notch filter MNF1 and the second notch filter MNF2 may be uniformly reduced. The parameter adjustment unit AF may adjust the notch depth until the limit value of the preset adjustment range is reached or until the overlap determination condition of the two notch filters is not satisfied.

  As a result of reducing the overlap between the two notch filters in this way, when a new vibration frequency component becomes obvious and the vibration level exceeds the reference, the notch filters in an invalid state other than the first notch filter MNF1 and the second notch filter MNF2. May be assigned to the suppression of the vibration frequency component. When only the first notch filter MNF1 and the second notch filter MNF2 are in the valid state, the notch filter control unit EVL switches the third notch filter MNF3 from the invalid state to the valid state. On the other hand, when there is no new notch filter that can be switched to the valid state, the parameter adjustment unit AF does not adjust the notch width or the notch depth of the first notch filter MNF1 and the second notch filter MNF2, and performs the initial adjustment. The value may be left as it is. In this way, exposure to new vibration frequency components can be avoided.

  When it is determined that the vibration level exceeds the threshold value (Y in S22), the parameter adjustment unit AF adjusts one notch filter to be larger than the other notch filter. In this embodiment, the notch width or notch depth of one notch filter is adjusted, and the notch width and notch depth of the other notch filter are maintained at the initial values (S26).

  The notch filter that is largely adjusted is selected according to the estimated vibration frequency component ωv. For the estimation of the vibration frequency component ωv, the above-described center frequency update process in the parameter adjustment unit AF can be used. This is because the center frequency obtained by the update process represents an estimated value of the vibration frequency ωv to be suppressed.

When the vibration frequency component ωv substantially different from the center frequencies ω ₁₀ and ω _{20 of} the first notch filter MNF1 and the second notch filter MNF2 is present beyond the reference, the parameter adjustment unit AF is the first notch filter MNF1. In addition, the notch width of the second notch filter MNF2 that gives a larger phase delay to the vibration frequency component ωv is narrowed. In this way, the influence of the phase delay on the vibration frequency component ωv by the notch filter can be reduced.

Here, it is assumed that the vibration frequency ωv is between the center frequency ω ₁₀ of the first notch filter MNF1 and the center frequency ω ₂₀ of the second notch filter MNF2. Then, when the center frequency ω ₁₀ of the first notch filter MNF1 is higher than the center frequency ω ₂₀ of the second notch filter MNF2, as can be seen from the phase characteristics of the notch filter shown in FIG. 2, the first notch filter MNF1 Delays the phase at the vibration frequency ωv, and the second notch filter MNF2 advances the phase. Thus, the parameter adjusting portion AF is estimated vibration frequency ωv is narrowed adjust the notch width of the first notch filter MNF1 in the case of more than the center frequency omega _20. Also, the parameter adjustment portion AF, when the estimated vibration frequency ωv is less than the center frequency omega ₂₀ is narrowed adjusts the notch width of the second notch filter MnF2.

Similarly, when the center frequency ω ₁₀ of the first notch filter MNF1 is smaller than the center frequency ω ₂₀ of the second notch filter MNF2, the parameter adjustment unit AF is configured to use the estimated vibration frequency ωv of the center frequency ω ₁₀ or more. The notch width of the second notch filter MNF2 is adjusted. Also, the parameter adjustment portion AF, when the estimated vibration frequency ωv is less than the center frequency omega ₁₀ adjusts the notch width of the first notch filter MNF1.

  Also in this case, the parameter adjustment unit AF adjusts the notch width of one notch filter until the limit value of the preset adjustment range is reached or until the overlap determination condition of the two notch filters is not satisfied. . When the Q value is used as a parameter representing the notch width, when the upper limit value of the adjustment range of the Q value is reached, the adjustment of the Q value is terminated at the upper limit value, and the adjustment of the notch depth is started. Also good. Only the depth parameter D of the notch filter to be adjusted may be greatly adjusted to reduce the notch depth of the notch filter. Alternatively, the notch depths of the first notch filter MNF1 and the second notch filter MNF2 may be uniformly reduced by adjusting the depth parameter D to be large for the first notch filter MNF1 and the second notch filter MNF2. . The parameter adjustment unit AF may adjust the notch depth until the limit value of the preset adjustment range is reached or until the overlap determination condition of the two notch filters is not satisfied.

Thus, the notch width or the notch depth is adjusted so that the overlapping degree of the first notch filter MNF1 and the second notch filter MNF2 is within the reference. Similarly, the notch width or notch depth of the notch filter may be adjusted so as to reduce the degree of overlap between the amplitude characteristics of the notch filter and the control band. For example, when the center frequency ω ₂₀ of the second notch filter MNF2 is smaller than the center frequency ω ₁₀ of the first notch filter MNF1, the Q value or the parameter D is set so that the frequency ω ₂₁ is larger than the upper limit value of the control band. May be increased.

FIG. 11 is a diagram schematically illustrating the overlap of notch filters according to an embodiment of the present invention. FIG. 11 shows frequency amplitude characteristics and frequency phase characteristics of the first notch filter MNF1 and the second notch filter MNF2. As in the example shown in FIG. 9, the second notch filter MNF2 is on the lower band side than the first notch filter MNF1. In FIG. 11, an intermediate frequency ω ₀₁₂ between the center frequency ω ₁₀ of the first notch filter MNF1 and the center frequency ω ₂₀ of the second notch filter MNF2 is displayed.

  The phase characteristic of the notch filter is uniquely determined if the amplitude characteristic is determined. Therefore, in the above-described embodiment, attention is paid to the overlapping state of the amplitude characteristics of the two notch filters, but the present invention is not limited to this. In one embodiment, the overlap between the two notch filters may be adjusted by focusing on the phase characteristics. In this way, the overlap between the two notch filters can be reduced.

As shown in the figure, when the center frequency ω ₁₀ of the first notch filter MNF1 is larger than the center frequency ω ₂₀ of the second notch filter MNF2, the parameter adjustment unit AF performs the phase by the first notch filter MNF1 at the intermediate frequency ω ₀₁₂ . The Q value may be adjusted so that the delay and the phase advance by the second notch filter MNF2 are equal to or less than βdeg. Instead of the Q value or together with the Q value, the depth parameter D may be adjusted similarly to the above-described embodiment. On the other hand, when the first center frequency ω ₁₀ is smaller than the second center frequency ω ₂₀ , the parameter adjustment unit AF performs phase advance by the first notch filter MNF 1 and phase lag by the second notch filter MNF 2 at the intermediate frequency ω ₀₁₂ . And the Q value or the depth parameter D may be adjusted so that each is less than or equal to βdeg. Intermediate frequency omega _012, for _{example, logω 012 = (logω 10 +} logω 20) / 2 may be determined so as to satisfy. The phase delay (or phase advance) β may be, for example, 30 degrees to 40 degrees.

  Furthermore, in one embodiment of the present invention, the parameter adjustment unit AF adjusts any notch filter to suppress the vibration level below a reference when the control band is expanded stepwise or continuously. Also good. In one embodiment, a command generation unit (not shown), a control unit VC (see FIG. 7), or an actuator control unit TC (see FIG. 7), which is a control device for generating a control input to a control target, For example, the control band is expanded to the high band side stepwise or continuously according to the user's designation. At this time, the parameter adjustment unit AF adjusts at least the first notch filter MNF1 based on the vibration level or the vibration frequency component.

FIG. 12 is a flowchart for explaining notch filter adjustment processing according to an embodiment of the present invention. This process is executed when the control band LBW is gradually expanded to the desired high band target value LBWx. In this process, as long as the vibration level does not reach the threshold value, the control band LBW is gradually expanded toward the target band LBWx. When the vibration level reaches the threshold value, the center frequency of the first notch filter MNF1 is first adjusted in order to reduce the vibration level. The control band LBW is further expanded until the vibration level reaches the threshold value. If the vibration level reaches again the threshold value, the parameter adjustment portion AF is adjusted in the first notch filter MNF1 depending on the relationship between the center frequency omega ₁₀ of the vibration frequency component ωv a first notch filter MNF1 Select a power parameter and adjust the parameter.

  As shown in FIG. 12, the control band LBW is first widened to the high band side by a predetermined amount ΔLBW (S30). That is, the upper limit value of the control band LBW is changed to a value that is larger by the predetermined amount ΔLBW. The notch filter control unit EVL determines whether or not the vibration level exceeds the threshold value (S32). It is preferable to determine whether or not the vibration level of the response to the command to the controlled object exceeds a threshold value. This determination threshold value is a threshold value for determining whether or not the vibration to be suppressed is sufficiently small, similar to the vibration level threshold value in the above-described embodiment. For example, this threshold value is empirical or experimental. Can be set as appropriate.

  If it is determined that the vibration level is within the threshold (N in S32), the control band LBW is further expanded to the higher band side by a predetermined amount ΔLBW (S30). Thus, the control band LBW is automatically expanded toward the target band LBWx until the vibration level reaches the threshold value.

If the vibration level is determined to exceed the threshold value (S32 of Y), the parameter adjuster AF adjusts the center frequency omega ₁₀ of the first notch filter MNF1 (S34). The notch filter control unit EVL determines again whether or not the vibration level exceeds the threshold value after adjusting the center frequency ω ₁₀ (S36). If it is determined that the vibration level is within the threshold (N in S36), the control band LBW is further expanded to the higher band side by a predetermined amount ΔLBW (S38). The notch filter control unit EVL determines again whether or not the vibration level exceeds the threshold value (S36).

When it is determined that the vibration level exceeds the threshold value (Y in S36), the notch filter control unit EVL determines the number of adjustments as an example of an end condition described later (S37), and then vibrates. The frequency component ωv is estimated (S40). If the number of adjustments has reached the set value (Y in S37), the adjustment process is terminated. Parameter adjusting portion AF is first select the parameters to be adjusted in the notch filter MNF1 depending on the relationship between the center frequency omega ₁₀ of the estimated oscillation frequency component ωv a first notch filter MNF1 (S42), that parameter Is adjusted (S44).

  In the adjustment process described above, the adjustment process ends when a predetermined end condition is satisfied. Therefore, the notch filter control unit EVL periodically determines whether or not an end condition is satisfied during the execution of the adjustment process. The termination condition includes that the control band LBW has reached the target band LBWx (S46). If the control band LBW has not reached the target band LBWx (N in S46), the notch filter control unit EVL determines again after adjusting the parameter whether the vibration level exceeds the threshold value (S36). The above adjustment process is repeated. The determination of the end condition whether or not the control band LBW has reached the target band LBWx is made by increasing the control band LBW by a predetermined amount ΔLBW in S30 and S38 after it is determined in S32 and S36 that the vibration level is equal to or lower than the threshold value. It is desirable to carry out before.

  Further, the termination condition may include that there are no notch filters that can be additionally supplied when the second to n-th notch filters MNF2 to MNFn can be sequentially input as described later. The end condition is preferably determined when the adjustment of the n-1th notch filter MNFn-1 is finished and the adjustment of the nth notch filter is started in S40 or S42. At this time, if the n-th notch filter MNFn cannot be inserted, the control band LBW is returned to the state before the predetermined amount ΔLBW is increased immediately before.

Further, the termination condition may include that the notch frequency ω ₁₀ or the vibration frequency component ωv is within the target band LBWx. This is because the notch filter should not be set within the target control band. The determination in this case is desirably performed after S34 and S40. When the termination condition (that is, ω ₁₀ <LBW) is satisfied after S34, the control band LBW is returned to the state before the predetermined amount ΔLBW is increased immediately before, and MNF1 is invalidated. When the end condition (ie, ωv <LBW) is satisfied after S40, the control band LBW is returned to the state before the predetermined amount ΔLBW is increased immediately before.

  Further, the end condition may include that the vibration level still exceeds the threshold value even when the parameter adjustment process (S44) is executed a predetermined number of times (S37). The determination in this case is desirably performed after it is determined in S36 that the vibration level has exceeded the threshold value. At this time, the control band LBW is returned to the state before the predetermined amount ΔLBW is increased immediately before.

In one embodiment, the parameter adjusting unit AF, when there is a vibration frequency component ωv in the first band set including the center frequency of the notch filter in the effective state, determines the center frequency of the notch filter as the vibration frequency component. It may be made to coincide with ωv. When the vibration frequency component ωv is in the vicinity of the center frequency, it is regarded as an error of the center frequency and the center frequency is adjusted. For example, when the vibration frequency component ωv is included in a predetermined band including the center frequency ω ₁₀ of the first notch filter MNF1, the parameter adjustment unit AF may match the center frequency ω ₁₀ with the vibration frequency component ωv. This predetermined band is, for example, a range for determining whether or not it is in the vicinity of the center frequency ω ₁₀ of the first notch filter MNF1, for example, a range of 85% to 115%. Alternatively, it may preferably be in the range of 95% to 115% of the center frequency ω ₁₀ of the first notch filter MNF1.

The parameter adjustment unit AF may adjust the notch width of the notch filter when the vibration frequency component ωv is in the second band below the first band. In this case, the center frequency is not adjusted and is maintained at the same value. The parameter adjustment unit AF may increase the Q value by a predetermined amount so as to narrow the notch width in the same manner as in the above-described embodiment. The second band may be a range in which the lower limit value of the first band described above is an upper limit value and a value at which the gain of the notch filter is a predetermined value is a lower limit value. The predetermined value of this gain is, for example, -3 dB. As the Q value is increased and the notch width is reduced, the second band is also reduced. By narrowing the notch width if such is the vibration frequency component .omega.v the low band side of the center frequency omega ₁₀ in the notch filter can be made smaller phase delay given to the oscillation frequency component .omega.v.

  The parameter adjustment unit AF may adjust the notch depth of the notch filter when the limit of the notch width adjustment range is reached. Assuming that the limit of the adjustment range of the notch width has been reached, the parameter adjustment unit AF performs the case where the vibration frequency component ωv is below the first band and the center frequency of the notch filter is close to the target control band LBWx. The notch depth of the notch filter may be reduced. The parameter adjustment unit AF may determine that the center frequency of the notch filter is close to the target control band LBWx when the center frequency of the notch filter is, for example, four times or less of the target control band LBWx. Further, assuming that the limit of the adjustment range of the notch width has been reached, the parameter adjustment unit AF, when the center frequency of the plurality of notch filters is included in the second band described above, You may make it make the notch depth of a notch filter shallow so that overlap may be made small.

  When the vibration frequency component ωv is present in the third band lower than the second band, the parameter adjustment unit AF ends the adjustment of the first notch filter MNF1 and changes the second notch filter MNF2 to the first notch filter MNF1. You may make it adjust similarly. That is, the second notch filter MNF2 may be adjusted so that the vibration frequency component ωv is suppressed. If the vibration level is not suppressed below the threshold value even by adjusting the second notch filter MNF2, the parameter adjusting unit AF sequentially turns on the third to nth notch filters MNF3 to MNFn to adjust the parameters. May be. Further, the parameter adjustment unit AF may adjust the parameters by sequentially inserting the second notch filter MNF2 or the like even when the vibration frequency component ωv is in the fourth band that exceeds the first band.

  In this way, the parameters of the notch filter to be adjusted are divided into the third, second, first, and fourth bands in order from the low band side, and depending on which band the vibration frequency component ωv is included in. Is selected. When the vibration frequency component ωv is in the vicinity of the center frequency, the center frequency is adjusted and the frequency component is suppressed. When the vibration frequency component ωv is in a predetermined range (second band) on the low band side of the center frequency, the notch width is preferentially adjusted so as to suppress the influence on the extended control band. When the limit of the adjustment range is reached, the notch depth is adjusted. When the vibration frequency component ωv is away from the center frequency (third and fourth bands), other notch filters are adjusted. In this way, it is possible to increase the control band to the target band designated by the user while suppressing resonance by the plurality of notch filters.

FIG. 13 is a diagram for schematically explaining an example of the adjustment process of the notch filter shown in FIG. The gain and phase of a closed loop control system are shown at the top and bottom of FIG. Gain peaks are seen at the frequencies ω _r1 and ω _r2 . The frequency ω _r2 has a larger peak than the frequency ω _r1 . The control band LBW is broadened step by step to LBW1, LBW2,..., And the state where the control band LBW is expanded to the target band LBWx is schematically shown. In the figure, dotted lines indicated as LBW1, LBW2,..., LBWx indicate positions where the gain in each control band becomes zero.

As can be seen from FIG. 13, first, the gain at the frequency omega _r2 when the control band is the LBW1 exceeds zero, the vibration becomes unstable frequency omega _r2 occurs. At this time, the center frequency ω ₁₀ of the first notch filter MNF1 is adjusted to coincide with ω _r2 . The width and depth of the first notch filter MNF1 take initial values Q = 1 and D = 0, respectively. By first notch filter MNF1 is set, the phase is delayed at a lower frequency than the center frequency omega _10. As a result, vibrations that are not unstable occur in the vicinity of the frequency ω _r1 included in the low band.

Assuming that the frequency ω _r1 is included in the second band, an adjustment is made to increase the Q value of the first notch filter MNF1. The width of the first notch filter MNF1 is narrowed, the phase delay at the frequency omega _r1 is improved. In this way, vibration near the frequency ω _r1 is suppressed.

When the vibration is suppressed, the control band is further expanded to LBW2. Gain exceeds zero at frequency omega _r1, so that the vibration frequency omega _r1 becomes unstable occurs. By Q value of the first notch filter MNF1 is already adjusted from an initial value to a large value, the frequency omega _r1 will be with respect to the center frequency omega ₁₀ included in the third band mentioned above. Therefore, the adjustment of the first notch filter MNF1 is finished, and the center frequency ω ₂₀ of the second notch filter MNF2 is adjusted to coincide with ω _r1 . Thus the second notch filter MnF2, vibration frequency omega _r1 is suppressed.

When vibration is suppressed, the control band is further expanded toward LBWx. At this time, the phase is delayed at a frequency lower than the center frequency ω ₂₀ of the second notch filter MNF2. At this time, vibration may occur in the band A where the phase delay is relatively large in the original phase characteristics. When the vibration frequency component is included in the second band, adjustment is made to increase the Q value of the second notch filter MNF2. If the Q value is excessively increased, the second notch filter MNF2 becomes extremely narrow, and the gain suppression effect in the band B becomes insufficient. Therefore, it is preferable that the adjustment range of the Q value has an upper limit so that the gain suppression effect in the band B is guaranteed. When the Q value reaches the upper limit by the adjustment, the depth parameter D is adjusted as described above.

In _contrast to the example shown in FIG. 13, the above-described parameter adjustment processing can be similarly applied to the case where the frequency ω _r2 has a smaller peak than the frequency ω _r1 . In this case, first the first notch filter MNF1 is to be set to a frequency omega _r1. The frequency ω _r2 exists on the high band side of the center frequency ω ₁₀ of the first notch filter MNF1. Therefore, in the process of expanding the control band, the vibration near the frequency ω _r2 can be suppressed to some extent by the side lobe of the first notch filter MNF1.

  10 adaptive notch filter, 12 notch filter section, 14 phase difference filter, 16 correction operation section, AF parameter adjustment section, EVL notch filter control section, MNF1 first notch filter, MNF2 second notch filter, PF prefilter PNF1 first pre Notch filter, PNF2 Second pre-notch filter, SW0 Adjustment target changeover switch.

Claims (5)

A notch filter for suppressing a natural frequency component of the control target included in a signal for generating a control input to the control target that may cause resonance;
A parameter adjusting unit for adjusting a parameter including a center frequency and a notch width of the notch filter,
The parameter adjustment unit selects a parameter of the notch filter to be adjusted according to a relationship between a vibration frequency component generated when the control band of the control target is expanded and a center frequency of the notch filter. A featured adaptive notch filter.   The parameter adjusting unit adjusts a notch width of the notch filter when the vibration frequency component is in a second band lower than a first band set including a center frequency of the notch filter. The adaptive notch filter according to claim 1.   The adaptive notch filter according to claim 2, wherein the parameter adjusting unit adjusts a notch depth of the notch filter when a limit of an adjustment range of the notch width is reached.   The parameter adjustment unit is configured to make the center frequency of the notch filter coincide with the vibration frequency component when the vibration frequency component is in a first band set including the center frequency of the notch filter. The adaptive notch filter according to any one of claims 1 to 3. Estimate the vibration frequency component generated when the control band of the control target to which the notch filter is applied is expanded,
According to the relationship between the vibration frequency component and the center frequency of the notch filter, the parameter of the notch filter to be adjusted is selected,
The notch filter parameter adjustment method comprising adjusting the selected notch filter parameter so as to suppress the vibration frequency component.

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