JPH02228282A - Filter - Google Patents

Abstract

PURPOSE:To facilitate setting of a coefficient without increasing the number of components by reading the coefficient from a coefficient table based on a parameter determined by a set switch, and calculating a transfer function of a filter by using the coefficient. CONSTITUTION:In a filter 11 for suppressing mechanical resonance of a motor, a digital signal handling section is inserted into a direct drive motor control system. Set switches 111, 112 set parameters for determining characteristics of the filter 11, digital coefficients to be used to calculate a transfer function of the filter are stored corresponding to parameters in a coefficient table 113, and the coefficient is read based on the parameters set by the switches 111, 112. Calculating means obtains the function of the filter 11 by using the coefficient read from the table 113, and a filter section 114 is set to the function obtained by the calculating means.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applied to a control system for a direct drive motor (hereinafter referred to as DD motor).
This invention relates to a filter that suppresses 1 resonance.

<Conventional technology> In a DD motor without a reducer, mechanical resonance is suppressed,
Improving control characteristics is a major challenge in practice.

As a measure to suppress mechanical resonance, as shown in FIG. 6, an analog filter was inserted into the motor control system.

In the figure, 1 is a DD motor to be controlled, 2 is an encoder that detects the rotation of motor 1, and 3 is an encoder for controlling the rotational position of the motor based on the deviation between the position command signal and the position detection signal of encoder 2. The 0 position control unit 3, which is a position control unit that outputs a control signal, handles digital signals.
/A converter to output an analog signal.

4 uses the output of the speed control unit 3 as a speed command signal, and the output of the encoder converted by the F/V converter 5 as a speed detection signal,
This is a speed control section that outputs a control signal for controlling the rotational speed of the motor based on these deviations.

6 is an analog filter that outputs the output of the speed control unit 4 as a signal to prevent mechanical resonance. 0 Preventing mechanical resonance is done by reducing the passing signal around the frequency that is the resonant rotation speed of the motor, or by reducing the passing signal at frequencies above this frequency. This is done by reducing the passing signal in the frequency range.

7 is a motor drive circuit that drives the motor 1 using the output of the analog filter 6 as a torque command signal.

<Problems to be Solved by the Invention> In such a system, only the position control section 3 is a digital system, but the other parts are analog systems.

Therefore, an analog filter has to be added, which increases the number of parts.

■It hinders miniaturization.

■Increase costs.

It included problems such as: Furthermore, since the filter coefficients were set using variable resistors, there was also the problem that they were difficult to set.

The present invention was made to solve these problems, and it is possible to save space and reduce costs compared to conventional filters without increasing the number of parts, and it is easy to set coefficients. The purpose is to realize a filter.

Means for Solving the Problems> The present invention is directed to Dairef! ...In a filter that is applied to a drive motor control system and suppresses the mechanical resonance of the motor, a setting switch that is inserted in a part of the control system that handles digital signals and that sets parameters that define the characteristics of the filter; A coefficient table in which digital coefficients used for calculating the transfer function of the filter are stored in correspondence with the parameters, and the digital coefficients are read out based on the parameters set by the setting switch, and digital coefficients read out from this coefficient table. This filter is characterized by comprising: a calculation means for calculating a transfer function of the filter using the calculation means; and a filter section that is set to the transfer function calculated by the calculation means.

Effect> In the present invention, the filter is a digital filter, coefficients are read out from the coefficient table based on the parameters determined by the setting switch, and the transfer function of the filter is calculated using the coefficients.

<Example> The present invention will be explained below using the drawings.

FIG. 1 is a diagram showing an example of the configuration of a system to which a filter according to the present invention is applied. Components in FIG. 1 that are the same as those in FIG. 6 are given the same reference numerals.

In this system, the motor 1, encoder 2, and motor drive circuit 7 are analog systems, and the rest are digital systems.

In the figure, 8 is a position control section that outputs a control signal in the form of a digital signal for controlling the rotational position of the motor based on the deviation between the position command signal and the position detection signal of the encoder 2.

9 is a speed converter that converts the output of the encoder 2 into a digital speed detection signal, and 10 is the output of the position control unit 8 as a speed command signal, and the rotational speed of the motor is determined based on the deviation between this signal and the speed detection signal. This is a speed control section that outputs control signals as digital signals.

Reference numeral 11 denotes a digital filter that converts the output of the speed control section 10 into a signal that does not cause mechanical resonance in the motor. Although the digital filter 11 handles digital signals, it removes mechanical resonance in the same manner as the analog filter described above.

A concrete configuration of such a system is shown in FIG. 2.

The symbols within each block in FIG. 2 are transfer functions.

Each code is as follows.

:Gain KA of position control section 8:Gain KDA of speed control section 10:Conversion coefficient of D/A converter of motor drive circuit 7 [
V/d i, g i t ] KVT: Voltage/torque conversion coefficient [N/VIM(s): Transfer characteristic of motor mechanical system J: Inertia [kg-m'] KPLIL: Rotation angle/pulse conversion coefficient [pulse / r a d] F(z): Transfer function of digital filter S: Lass operator z: Z conversion operator Vr N: Speed command signal [digit] Eposx:
Position detection signal [pulse] VE t :Velocity detection signal [digit] χ<n>:n
Input y<n> of the digital filter in the n-th sampling period: Output Q of the digital filter in the n-th sampling period: Q value at resonance Here, the dimension [digit] is a digital signal of a predetermined number of digits. This is what is shown.

Further, in the digital filter 11, reference numerals 111 and 112 are rotary switches for setting parameters of the digital filter.

Reference numeral 113 denotes a coefficient table in which parameter values and coefficients used for calculating the transfer function of the digital filter are stored in correspondence with each other. Coefficients are read from the coefficient table 113 based on the parameters set by the switches 111 and 112.

114 is a filter section that is set to a transfer function calculated based on the coefficients read from the coefficient table 113.

If the digital filter 11 is a continuous time system, it will have the characteristics of a second-order notch filter expressed by the following equation.

ωo: Two-notch frequency The frequency characteristics of the notch filter are as shown in FIG.

Since it is actually a sample value control system, the transfer function F(z) of the digital filter 11 is expressed as follows in equation (1): The distance between the input χl) and the output y<n> is as follows.

This is done in the following form by expanding the formula.

τ: sample period After bilinear transformation using , it is given by the following equation.

+a' 2 -2a 2 +a2 (aωo / Q) ten ω. 2 2a2 a ωo / Q ) -to ω. 2=ωQ
2 =2ω0 =ω02 =a2− =2ωo2 ==a2 + (.

The digital filter at the nth sample period is also the parameter ωo that determines the characteristics of the actual digital filter.
+Q is set with hexadecimal rotary switches 111 and 112, and the set ω. .

Coefficients A0~A2°BO~B used in calculations according to Q
2 is read from the coefficient table. Based on this coefficient, the transfer function F(z) is calculated using equation (5).

FIG. 4 shows a flowchart for determining the transfer function F(z).

In the figure, reading the setting parameters of the setting switches 111 and 112 and reading the coefficients of the coefficient table 113 is 50.
The calculation is performed at a sampling frequency of Hz, and the calculation of the transfer number F(z) is performed at a sampling frequency of 2kHz. As a result, the values of the parameters and coefficient table are read every time the transmission interval number F(z) is calculated 40 times.

Note that the two sample frequencies mentioned above are 50Hz and 2
It may be a value other than kHz.

In the embodiment, the digital filter may be a Butterworth type equalizer filter in the case of a continuous time system.

The transfer function of a third-order Butterworth equalizer filter in a continuous time system is given by the following equation.

8, =-bai2. ♂-Ra1 2σ Flash Q) to-3♂-2c
prisoner, -2λsimplified-3-2 8--30y' -zoju3. +lcxw, +3
H.

1 + AO-Os" + 2-♂ωi 5ψ: 8) - to +
Nogome Q1 - λαω is 10ω.

? , 23 mer λ father →, -2 long 1 copy, hi, 6 -3 to 12 α2 ω, ÷ 2 α weak, +30 Gochiri 2 03 + 2 - α 1 ri 1 earth λα, + (, 3゜ ω,: attenuation Start frequency ω2 Two attenuation end frequency The actual filter calculation is performed in the form of the following equation by expanding equation (7).

The frequency characteristics of the filter are shown in FIG.

By performing bilinear transformation on this, the following equation is obtained.

Kihehe (vomit) - Bx5 (dream, -3) - bet (ha, bite) - B
1-+i->)ly) In this case, set the setting switches 111 and 112 to ω.

Used to set ω2, and also set the coefficient table to A0 to A and 8.
．． ~ Prepare for B.

<effect> According to the present invention, the following effects can be obtained.

■By digitizing the resonance suppression filter, configuring it with firmware, and mounting it on an existing microprocessor, space can be saved without increasing the number of components.
Moreover, it reduces costs.

■In general, it is easier to configure and change software than to configure and change hardware, so there is potential for advancements such as artificial intelligence such as auto-tuning functions.

■If multiple types of coefficient tables are provided on the same firmware and an external switch is provided to set the filter type, the filter type can be changed by switching the switch.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an example of application of the filter according to the present invention, FIG. 2 is a diagram showing the specific configuration of FIG. 1, and FIGS. 3 and 5 are filter characteristics. FIG. 4 is an explanatory diagram of the operation of the digital filter, and FIG. 6 is a diagram showing an example of a conventional filter. DESCRIPTION OF SYMBOLS 1... DD motor, 2... Encoder, 8... Position control part, 9... Speed converter, 10... Speed control part, 11... Digital filter, 111, 112...
Setting switch, 113...Coefficient table, 114...
・Filter section. ? , 3 Figures O Monthly 5 Figures - Kyoichi Maho 4-1

Claims (1)

[Claims] In a filter that is applied to a control system for a direct drive motor and suppresses mechanical resonance of the motor, the filter is inserted into a part of the control system that handles digital signals, and is configured to set parameters that define the characteristics of the filter. A setting switch to be set, a coefficient table in which digital coefficients used for calculation of the transfer function of the filter are stored in correspondence with the parameters, and from which the digital coefficients are read out based on the parameters set by the setting switch, and the coefficients A filter comprising: a calculation means for calculating a transfer function of the filter using digital coefficients read from a table; and a filter section set to the transfer function determined by the calculation means.