JPS61296403A - Digital control device - Google Patents

Abstract

PURPOSE:To detect the abnormality of an outer environment and to suppress the runaway of a control system by estimating the position of a controlled system properly on the basis of a controlled variable applied to the controlled system considering a model of a control system. CONSTITUTION:If the control system is normal, relation approximate to H(z)thetan= G(z)In can be formed between the position thetan of the controlled system which is a sampling value and the controlled variable In5. Provided that (n) is sampling time, G(z-1)=A1.Z<-1>+...+Ak.Z<-k> is the k-th mode of the control system and H(z-1)=1+B1.Z<-1>+...Bm.Z<-m> is the m-th model. When the position of the controlled system which is estimated from thetan2 and In5 is defined as Sn, (1+B1.Z<-1>+...+Bm.Z<-m>)Sn=(A1.Z<-1>+...+Ak.Z<-k>)In is formed, and when an error from the practically obtained thetan2 and an allowable error (e) are satisfied with ¦Sn-thetan¦<e, the control system is decided as normal. An error signal 14 is outputted to a selector 15 as '0' in case of the normal signal or '1' in case of abnormal. When the signal 14 is '1', the selector 15 switches the control variable 5 to 17 '0' to stop the controlled system.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention detects abnormalities in the surrounding environment of a controlled object, such as a measurement environment, a data converter, and a data transmission path, and prevents a control system from running out of control. The present invention relates to a digital control device that can perform the following functions.

[Conventional technology]

Generally, a digital control device has a configuration as shown in FIG. In FIG. 3, (1) is target position data Xn
, (21 is the controlled object position θn, and (3) is Xn(
The servo control circuit (4) is the deviation Bn between 11 and θn(2).

The control amount In of (5) is output according to In (3).

[Problem that the invention seeks to solve]

However, if an abnormality occurs in the means for measuring the controlled object position θn(2) or in the means for transmitting the measured data, the controlled variable In(51) may continue to be output inappropriately. had the problem of causing the control system to run out of control.

For example, even if an abnormality occurs in the means for measuring the controlled object position θn(2) and the controlled object is activated, the controlled object position θn(2)
becomes a constant value, the target position data Xn
(1) and the controlled object position θn(2) becomes constant, and the corresponding control amount In(5) also continues to output a constant value, causing the control system to run out of control in a certain direction.

This invention was made to solve such problems, and takes into account the model of the control system and appropriately estimates the position of the controlled object from the control amount given to the controlled object, thereby detecting abnormalities in the surrounding environment. Detected.

The purpose is to prevent the control system from running out of control.

[Means for solving problems]

The digital control device of the present invention estimates the current position of the controlled object from the previous position of the controlled object and the control amount, taking dead time into account, and compares it with the inputted current position of the controlled object. The system is equipped with an abnormality detector that detects an abnormality in the environment, and a selector that switches the output to the controlled object based on the error signal output by the abnormality detector.

[Effect]

In this invention, the abnormality detector determines whether or not the control system is operating properly, and if the control system is operating properly, the output of the servo control circuit is used as the control amount to determine whether the control system is operating inappropriately. In this case, the control system is stopped by setting the control amount to "a".

〔Example〕

The present invention will be specifically explained below with reference to an embodiment shown in FIGS. 1 and 2.

FIG. 1 is an overall configuration diagram of a control system including a digital control device according to the present invention.

In FIG. 1, (6) is target position data Xn (1)
The digital control device according to the present invention outputs a controlled variable In(5) from a controlled object position on(2), and the controlled variable In(5) is converted into an analog variable by the digital-to-analog converter in (7), and ( The signal is appropriately amplified by the amplifier 8) and becomes an input to the drive machine (9) which is the controlled object, and the drive machine (9) operates according to the control amount.

When the drive machine (9) operates, the position is detected by the connected synchro oscillator nal, and is fed back as the controlled object position θn(2) via the synchro oscillator I and the digital converter.

FIG. 2 is a diagram specifically showing the digital control device (6), and (2), (31, and (51) are the same as in FIG. 1.

In FIG. 2, z is a servo control circuit.

The deviation Fjn (3) is used as an input to realize a control law that determines the control amount In (51) that optimizes the system-dependent evaluation function.

(13 is an abnormality detector, which determines whether the control system is normal or abnormal based on the controlled object position θn(2) and the control amount I n (51), and outputs an error signal α4.

In other words, the controlled object position θn(2
) and control f In+51 if the control system is normal.

It can be approximated by the following relationship.

H(z)・an = G(z)・In The transfer function of an actual control system is always dimensionless.

When this is taken into consideration, sufficient approximation cannot be achieved unless the above model is used.

Here, n: Sampling time θn; Number/time time side target position work n; Controlled amount G(z-1) at sampling time n; Next model of the control system G(z-1)=
AI・Z−”+−...+Alc・Z−'H(z−1);
m-order model of control system H (z-1) = 1 +81 ・Z-1+ −+ Bm
-Z-” Therefore, the controlled object position θn(2) and the controlled amount In(5
1, if the estimated control target position is an, then s
n is (1+81 ・Z−′+ ・・−+8m −Z′)
8n=(AI ・Z−'10・−−−−−+Ak−Z−
k) The actually obtained controlled object position θ given by In
The error with n(2) and the system-dependent tolerance range e
Toga.

l5n-an1(e If the following is satisfied, it is determined that the control system is normal.

The error signal α4 outputs "a" when the control system is normal, and outputs "1" when the control system is abnormal, and is input to the (to) selector.

The selector α selects the output of the servo control circuit tta when the error signal I is “0”, and selects the output − of the servo control circuit tta when the error signal I is “1”.
In this case, the control system is prevented from running out of control by switching the control amount (5) to "θ" of αD and stopping the controlled object.

Although the above embodiment uses a synchro oscillator for measurement, the present invention can also be applied to other means capable of measuring one position.

〔Effect of the invention〕

As described above, according to the present invention, by considering a model that can sufficiently approximate the control system even when an abnormality occurs in the position measuring means of the controlled object, the synchronized digital converter, or the digital-to-analog converter. , it is possible to detect this accurately and with high sensitivity, and furthermore, it is possible to detect abnormalities in the controlled object, and has the advantage of suppressing runaway of the control system.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of a control system including a digital control device according to the present invention, Fig. 2 is a diagram specifically showing a digital control device (6), and Fig. 3 is a diagram showing a conventional digital control device. It is. In the figure, (1) is target position data Xn, (21 is controlled object position θn, (3) is deviation En, (41 is servo control circuit, (5) is control tIn, (61 is digital control device, (7 ) is a digital-to-analog converter, (
8) is an amplifier, (9) is a driver, α1 is a synchro oscillator, α9 is a synchro digital converter, UJdf-bo control circuit, and Q3 is an abnormality detector. I is an error signal, 149 is a selector, and αe and αη are output values. It should be noted that the same or corresponding parts in FIG. 1 are denoted by the same reference numerals.

Claims (1)

[Claims] Using a servo control circuit that inputs the error from the target value and outputs the controlled amount to the controlled object, and a model that can sufficiently approximate the control system from the controlled amount to the controlled object, the current position of the controlled object is calculated. an abnormality detector that detects an abnormality in the surrounding environment of the servo control circuit by estimating and comparing it with the input current position of the controlled object; What is claimed is: 1. A digital control device comprising a selector that switches an output to a controlled object based on an error signal, and suppresses runaway of a control system due to an abnormality in the surrounding environment.