JPS63257487A - Controlling method for servo-motor - Google Patents

Abstract

PURPOSE:To facilitate a servo-motor to be stably controlled, by fixing an identified parameter on this upper or lower limit value, when the adaptively identified parameter in speed controlling system exceeds the previously set upper or lower limit value. CONSTITUTION:By an adaptive identification mechanism c, the ideal model b of the whole objective plant and the output difference e(t) of a controlling system are set to be evaluated factors, and an interating gain K1 and a proportional gain K2 in the controlling system are controlled to minimize the evaluated factors. In this case, when an adaptively identified parameter exceeds a previously set upper or lower limit value, then the identified parameter is fixed on the upper or lower limit value. As a result, even when disturbance is generated, then speed controlling can be stably performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a servo motor control method, and particularly to a servo motor control method that can accurately control the speed of a servo motor by adaptive control even when a disturbance occurs.

(Prior Art) The feedback system of a conventional speed-controlled servo motor can be shown in a block diagram as shown in Fig. 5. In Fig. 5, K is an integral gain, K2 is a proportional gain, and Jl
is the inertia of the motor rotor, and α is the variable parameter, in this case the inertia of the load.

When an input signal U (S) is applied to the servo motor, the gain of the servo motor is adjusted by such a feedback system, and a predetermined control is performed on the output y (s).

(Problem to be Solved by the Invention) By the way, it is thought that a low rigidity spring coefficient exists between the inertia of the load and the inertia of the motor rotor, so when a disturbance occurs, the inertia of the load decreases. Since the inertia, that is, the parameter α fluctuates, there is a problem that the servo motor cannot be controlled with high accuracy. Therefore, the present invention aims to solve the problems of the prior art and provides a method for controlling a servo motor using an adaptive control system.

(Means for Solving the Problems) The present invention provides a method for controlling a servo motor that performs speed control by configuring a model reference adaptive control system for a speed control system of a servo motor. If the parameters of the control system exceed the upper or lower limit values of the parameters prepared in advance for the servo motor model, fix the identified parameters to either the upper or lower limit values or change the speed control system. , if a model reference adaptive control system is constructed and the output of the speed control system exceeds the two model outputs calculated by giving upper and lower limit values to the model, then the identified parameters of the speed control system are The problems of the prior art described above are solved by changing the control force L%a of the servo motor, which is characterized by setting the value to the previous identification parameter value.

(Function) The present invention applies a model reference adaptive control system to the speed control system of the servo motor, so even if a disturbance acts on the speed control system, the load parameter (inertia inertia) does not change and the servo motor can be controlled stably.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 6th
The figure is a block diagram illustrating an example of general adaptive control. In this example, an ideal model of the entire target plant is considered in advance, and the output difference e (
t) is used as an evaluation quantity, and parameters within the control system are determined so as to minimize it. Therefore, even when disturbances etc. act on the plant, adaptive control is performed that changes the characteristics of the plant to meet the required conditions.
The plant will always exhibit behavior equal to the model.

The present invention controls a servo motor using such a model-based adaptive control system. In FIG. 3, which is a block diagram of an embodiment of the present invention, signals from a rotary encoder or the like are fed back to the speed control system a of the servo motor as a position signal e2 and a speed signal el. Kt is a torque constant, d(s) is a disturbance, and other elements are the same as those shown in FIG.

b is the model and C is the adaptive identification mechanism. Adaptive identification mechanism C
As explained in FIG. 6, is the output signal of model b,
The integral gain is set to 1. so that the deviation e(1) from the output signal of the speed control system a is minimized. Control the proportional gain to 2.

This allows the servo motor to perform the same operation as model b regardless of the disturbance d(s).

However, the model-based adaptive control system shown in the block diagram of FIG. 3 is based on the premise that output regulation is performed so that input and output match in response to disturbances.
In this case, the adaptive control system produces an identification error of the parameter α due to the disturbance. Therefore, consider adaptive control for a speed control system as shown in FIG. 4 in which the output regulation condition is removed. An example of the adaptive control system of the present invention for the speed control system of FIG. 4 is shown in FIG. 1 as shown in FIG. It is considered as primary.

Here, the model parameter σ1 is the output y (5) of the speed control system is rcs) = 1/[1+((Jt ”a)/(k2K
t))

Next, in order to control the response of the speed control system to be constant with respect to the parameter variation α, the adaptive identifier 411c uses α
The proportional gain is identified and the proportional gain is adjusted by 2. At this time, the proportional gain 2 is ('1 + α)/(k' 2 Kt) →
Jt/(k2 Kk)...(3) It is adjusted so that it becomes.

In addition, using the output y (S) of the speed control system a, the upper limit σ weight wax and the lower limit σIWin of the parameter σl prepared in advance in the model b, y(s)−(u(s)/(1+σ1 sin s)
) ... (4)y(s)-(ucs)/C
1+σ1 轻ax s)) ... (5
). Adaptation If the identified parameter (load inertia) exceeds the upper or lower limit of the model parameter prepared in advance due to the load position, etc., the identified parameter is changed to the upper or lower limit of the parameter. Stable control is performed by fixing it to either one.

Furthermore, in equations (4) and (5), the output y of the speed control system
(s) is the model output 1 calculated by giving upper and lower limit values to model b, that is, (U (S) / (r + ty (rs
rn s) ), and the model output 2, i.e. (u
(s)/(1+σ111a! s)), the value of the identification parameter, ie, (J1+α)/, is controlled to be 2'Kt to the previous identification parameter value. This allows crl win <(Jl
+a)/K 2 'KL<crl wax...
(6) Even if the output e (s) of the adaptive identification mechanism is e(s
)<(u(s)/(1+ (rl Ila! s))
−(7)e(s)>(u(s)/(1+σ1 w
in s)) (8), and the speed control system is stably controlled even before adaptive identification.

In addition, t515! In the block diagram of J, the conditions for output regulation are excluded, but if the conditions for output regulation are taken into account, a control system like the one shown in Figure 2 may be configured.In other words, in this case, the speed The difference e (t) between the output y (s) of the control system a and the output of the model b is calculated by using an integrator d with an appropriate gain of 5 together with an adaptive identification mechanism C.
(Effects of the Invention) As explained above, the present invention configures a model-based adaptive control system for the speed control system of a servo motor, and applies adaptively identified parameters to the speed control system. If it exceeds the upper or lower limit value of a parameter prepared in advance in the model, the identified parameter is fixed to either the upper or lower limit value, so stable speed control can be performed even when disturbance occurs. Ru.

Also, if the output of the speed control system exceeds the difference between model output l and model output 2 calculated by giving upper and lower limit values to the model, the value of the identification parameter is set to the value of the previous identification parameter. By the way.

The speed control system can be controlled stably even before the parameters are adaptively identified.

Furthermore, if the output difference between the speed control system and the model is fed back to the speed control system via an integrator with an appropriate gain, the conditions for output regulation will be satisfied, so the servo motor will Input and output signals can be matched.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of one embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of another embodiment of the invention, and Figs. 3 and 4 form the premise of the present invention. FIG. 5 is a block diagram showing an example of a servo motor feedback system, and FIG. 6 is a block diagram showing a general example of the adaptive control system. a... Speed control system, b... Model, C... Adaptive identification mechanism, d... Integrator. Patent applicant: Representative of FANUC Co., Ltd. Patent attorney: Minoru Tsuji Figure 4

Claims (3)

[Claims] (1) In a servo motor control method that performs speed control by configuring a model reference adaptive control system for the speed control system of the servo motor, the adaptively identified parameters of the speed control system are A method for controlling a servo motor, characterized in that when an upper or lower limit value of a parameter prepared in advance is exceeded, the identified parameter is fixed at either the upper or lower limit value. (2) In a servo motor control method in which a model reference adaptive control system is configured for the servo motor speed control system to perform speed control, the output difference between the speed control system and the model is A method for controlling a servo motor, characterized in that when an output difference between two models calculated by giving a lower limit value is exceeded, the value of an identification parameter of a speed control system is set to the previous identification parameter value. (3) A claim characterized in that the output difference between the speed control system of the servo motor and the model is input to an adaptive identification mechanism, and is fed back to the speed control system via an integrator having an appropriate gain. Paragraph (1) or (
The servo motor control method described in section 2).