JPH0297291A - Automatic controller for motor - Google Patents

Abstract

PURPOSE:To prevent instability with the inertial change of load by providing a control system with a means varying a control parameter by a fuzzy inference based on the vibration components of the acceleration or speed of a motor. CONSTITUTION:The speed signal of an encoder E is input to a second comparison section 4, and the signal of a speed gain change section 5 as a means altering a control parameter is transmitted over a servo amplifier 6, thus driving a motor M. Variation is acquired by a fuzzy inference using the magnitude of acceleration obtained from the speed of the motor M as an input value in the speed gains KV of the speed gain change section 5, thus preventing instability with the inertial change of load.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to an automatic control device for a motor, and more particularly to an automatic control device for a motor whose load inertia varies.

(Summary of the Invention) In the present invention, the amount of change in the parameters of the mU control system is determined based on the magnitude of acceleration or the vibration component of the speed of the motor, and the changed control parameters are used to drive and control the motor to reduce the load. This prevents control instability caused by inertia changes.

(Prior art and its problems) Conventionally, automatic control of motors whose load inertia changes, such as motors used in winding machines, capacitor film winding machines, articulated robots, etc., prevents unstable operation due to fluctuations in inertia. In order to achieve this, the control gain is adjusted in accordance with the variation in inertia.

In other words, the transfer function of the control system is S2+2ζωnS+ω2
It is expressed by a quadratic function expressed as n=o (ωn: natural angular frequency, ζ: damping coefficient, S nira plus operator), but increasing inertia reduces the damping coefficient ζ, making the control system oscillatory, and this Therefore, the control parameters of the control system are changed according to the inertia.

To adjust the control parameters, that is, change the control gain, there is an identification method that calculates the speed gain from various inertias, or a method that calculates the inertia and speed gain according to the motor angle information in advance using a mathematical model. A table method is used in which the angle information is stored in a table and the speed gain is adjusted by reading it out from the table based on the angle information during actual operation.

However, in the conventional gain adjustment method described above, especially in the former identification method, the amount of calculation is extremely large.
Not only does it require a large arithmetic unit, but it is also unsuitable for control systems that require high-speed response.The latter table method not only requires a huge number of memory elements, but also requires a speed gain. The values of are discrete, which causes vibrations, and there are also disadvantages in that appropriate adjustments cannot be made when the table is formed by an inaccurate mathematical model.

(Objective of the Invention) The present invention has been made to solve the problem described in "-", and detects the inertia change from the magnitude of the acceleration of the motor or the vibration component of the speed, and uses this detected value to determine the speed. It is an object of the present invention to provide an automatic motor control device that calculates the gain by fuzzy inference and can perform stable control with a small amount of calculations and a small amount of memory.

(Structure and Effects of the Invention) In order to achieve the object stated in -1-, the present invention provides a motor whose structure is composed of a motor that drives a load whose inertia changes, and a control system that controls this motor according to a set target value. In the automatic control device, the control system is equipped with means for changing control parameters of the control system by fuzzy inference based on the magnitude of the acceleration or the vibration component of the speed of the motor. .

According to the present invention, control parameters corresponding to inertia fluctuations are determined by fuzzy reasoning using the configuration described in item 1, so that it can be realized with a small amount of calculations and a small storage capacity. As a result, the hardware configuration can be simplified and stable control without vibration can be achieved.

(Example) Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a block diagram showing a schematic configuration of the device of the present invention, in which a target value of a predetermined motor angle is inputted manually to a first comparator 1 formed from a subtraction circuit, and the rotation axis of a motor M is The speed signal from the directly connected encoder E is integrated by the detection section 2, and the resulting position signal is input manually. The deviation signal from the first comparator 1 is transmitted to a control unit 3 formed from an amplifier.
Here, it is processed by a predetermined position gain (Kp), and the output signal is sent to the second comparison section 4 formed from a subtraction circuit. The second comparator 4 manually processes the speed signal of the encoder E and receives an output value from a speed gain changer 5 corresponding to a means for changing control parameters, which undergoes subtraction processing and is sent to the servo amplifier 6. Sent out. The output value (drive current) from the servo amplifier 6 amplified with a predetermined gain (KA) is sent to a motor (servo motor) M, thereby driving the motor M.

The speed gain Kv of the speed gain changing section 5 is determined by fuzzy inference using the magnitude of acceleration determined from the speed of the motor M as an input value.Before explaining this fuzzy inference, the present invention In order to facilitate understanding of the above, the transfer function of the control system shown in FIG. 1 will be devised.

The transfer function of the control system shown in FIG. 1 can be expressed by the following equation.

... (1) Here, ωn is n-K p K A J ... (2) ζ-±KV KA 2 KpJ ... (3) (Kp is the position gain, KA is the fixed gain of the servo amplifier 5 , Kv is the speed gain, J is the inertia of the motor M and the load, ωn is the natural angular frequency, and ζ is the damping coefficient. 2, and ζ to 0. If the value is set between 7 and 1, a stable control system without vibration can be realized. Therefore, depending on the change in inertia J, this natural angular frequency ωn
It is a good idea to keep the damping coefficient ζ constant while changing the damping coefficient ζ.

By the way, as is clear from the above equation (2), there is no problem because the natural angular frequency 0 changes according to the change in inertia J even if the position gain Kp is constant. It can be seen that the velocity gain K v must be changed in accordance with the inertia J as shown in FIG.

As mentioned above, in the past, this speed gain Kv was changed using the identification method or the table method.
Fuzzy inference is used in the present invention.

In other words, in the speed gain characteristic during proper control without vibration, no acceleration component appears as shown in Fig. 2(a), but
As shown in (b) and (C) of the same figure, when the velocity gain K v is small and the velocity gain K v is considerably small, a appears in the acceleration component diagram, so the fuzzy calculation is performed based on the magnitude of this acceleration a. The amount of change in speed gain is determined by inference. Note that since the magnitude of this acceleration corresponds to the vibration component of the speed of the motor M, it can also be determined from this vibration component.

In this embodiment, the speed gain Kv is changed to increase in accordance with the amount of increase in the inertia J, using the case where the inertia J is the smallest, that is, the speed gain Kv is the smallest, as a reference. For this reason, first, the magnitude of the acceleration a is measured while the motor M is rotating at a constant speed.

This acceleration+orthotropy is performed by differentiating the velocity signal, but it may also be obtained from a separate acceleration sensor.

Based on the obtained acceleration a, the amount of change in the velocity gain Kv is derived by the following four fuzzy rules.

(1) if a=ZR (2) if a=PS (3) i fa=PM (4) 1fa=PL (Here, the language value ZR is 0 thenΔK v = Z R thenΔK v = P 5 thenΔK v = (PM thenΔK v =P L PS means small, PM means medium, and PL means large.) These rules are quantified by the membership function shown in FIG. The membership functions shown here include both the condition part of if~ and the conclusion part of then~. Using this membership relationship, we will explain an example of fuzzy inference when the magnitude of acceleration at a certain moment is ao.
Explaining based on the figures, FIG. 4(a) shows a conditional part, and FIG. 4(b) shows a conclusion part. From this inference process, the fitness of the conditional part (here, ZR
(related only to PS) are calculated, and the membership function of the conclusion part is modified according to the degree of fitness. Finally, the membership functions of the conclusion part are superimposed to obtain the membership function of the conclusion, as shown in FIG.

The amount of change in the actual velocity gain Kv is ΔK v O, which is the centroid of the membership function of the conclusion, and the new velocity gain K v is the velocity gain I(VOX (1+ΔKV[]) when the inertia J is the smallest. This new speed gain Kv is sent to the second comparator 4 and used as a control system parameter.

In this embodiment, the speed gain Kv corresponding to the increase in inertia J is determined by fuzzy reasoning based on the magnitude of acceleration a, so the optimum speed gain can be changed smoothly with extremely small amount of calculation and storage capacity. There is.

Incidentally, although the two series of embodiments show an example in which the inertia J increases with the passage of time, it goes without saying that the present invention can also be applied to a case in which the inertia J gradually decreases.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the general structure of the apparatus of the present invention, FIG. 2 is a characteristic diagram of speed gain, and FIGS. 3 and 4 are membership functions. 1... First comparing section 2... Detecting section 3... Control section 4... Second comparing section 5... Speed gain changing section (changing means) 6... Servo amplifier M... Motor E... Encoder patent applicant Tateishi Electric Co., Ltd.

Claims (1)

[Claims] 1. In an automatic motor control device consisting of a motor that drives a load whose inertia changes and a control system that controls this motor according to a set target value, the control system has a control system that controls the magnitude of the acceleration or speed of the motor. An automatic control device for a motor, comprising means for changing control parameters of a control system by fuzzy inference based on vibration components.