JPH06131002A - Control device - Google Patents

Abstract

PURPOSE:To provide the controller for deriving a characteristic and a PID constant of a control object in a short time from a rise time of a measured value. CONSTITUTION:Time t1, t2 until a measured value PV at the time when a prescribed manipulated variable output MV is given to a control object 2 reaches prescribed values PV1, PV2 being lower than the set value PV is derived by a measuring means 11, and from this time t1, t2, characteristics of a time constant T and a dead time L of the control object 2 are derived by a characteristic arithmetic means 12, and from these values of T, L, a PID parameter control constant is derived by a PID arithmetic means 13, and controlled by a control means 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for controlling a process amount such as temperature of a controlled object.

[0002]

2. Description of the Related Art When PID control is performed on a control target, it is necessary to obtain a PID constant (control parameter) in advance. For example, there is a limit sensitivity method for performing on / off control of a target set value and obtaining from the control result, or an identification method for giving an identification signal such as an M series signal to a control target and obtaining from the result.

[0003]

However, in the limit sensitivity method, since the output of the operating end is switched between 0% and 100%, the durability of the operating end becomes a problem. Further, in the identification method, control is impossible while the identification signal is being input.

In view of the above points, an object of the present invention is to provide a control device in which the characteristic of the controlled object, the PID constant, etc. are obtained from the rise time of the measured value, and the adjustment time is shortened. .

[0005]

According to the present invention, a measured value is lower than a set value when a predetermined output is supplied to a controlled object.
Measuring means for measuring two times to reach one predetermined value, characteristic calculating means for calculating the time constant and waste time of the controlled object based on the two times of the measuring means, and the output value of the constant calculation. And a PID calculation means for calculating a PID constant.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

In the figure, reference numeral 1 denotes a control device, which outputs a manipulated variable M from a set value SV and a measured value PV of a controlled variable of a controlled object 2.
V is supplied to the controlled object 2 to perform predetermined control. Then, the control device 1 has a time t1 at which the measured value PV reaches two predetermined values PV1 and PV2 lower than the set value SV when the control target 2 is given a predetermined manipulated variable output MV of, for example, 100%. , T2, and the controlled object 2 based on the two times t1 and t2 of the measuring means 11.
Characteristic calculation means 12 for calculating characteristics such as time constant T and waste time L of the characteristic calculation means by an experimentally obtained relational expression, and a PID constant (control parameter) is calculated based on output values L, T of the characteristic calculation means 12. It is composed of PID calculation means 14 and the like,
These calculations are executed by a microcomputer or the like.

Next, a diagram of measured values with respect to time t in FIG. 2 will be described.

The measuring means 11 has a first set value PV and a first set value PV corresponding to a ratio X of an initial measured value SV0.
Predetermined values PV1 and PV2 are defined by the following equation.

PV1 = (SV-PV0) × X1 + PV0 (1) PV2 = (SV-PV0) × X2 + PV0 (2) Since the rise is seen early, for example, X1 = 0.1,
It suffices to set X2 = 0.2. And controlled object 2
When the stepwise manipulated variable output MV equivalent to 100% is supplied to the measured value PV, the time t at which the measured value PV reaches PV1 and PV2
The measuring means 11 obtains 1 and t2.

The time constant T of the controlled object 2 is calculated from the time t1, t2 according to the following formula which is experimentally obtained in advance.
The characteristic constant of the dead time L is obtained by the characteristic calculation means 12.

T = (t2−t1) / A (3) L = (t2−t1) T · B / 100 (4) A and B are when the characteristic of the controlled object 2 is a first-order lag system. A is an coefficient obtained experimentally from the response, and A is 0.12 to 0.
14, in the 2.7-3.3 position of B, X1 = 0.1, X =
This is appropriate for 0.2, and if A = 0.132 and B = 3, then equations (3) and (4) are as follows.

T = (t2-t1) /0.132 (5) L = 3 · (t2-t1) /0.132×100 (6) From these equations (5) and (6), the time constant T , When the dead time L is obtained, the PID constant is calculated from the following equation by the adjustment rule of Ziegier Nichols or the like.
Calculated by 4 and found.

P = k1 · T / L = 1.2T / L (7) I = k2 · L = 2L (8) D = k3 · L = 0.5L (9) The above coefficients k1, k2, k3 are For example, in the above-mentioned numerical values, these numerical values may empirically vary by about ± 10% to ± 30%.

Based on the PID constant obtained in this way, the control means 14 immediately performs a predetermined PID calculation and switches from 100% to the output MV by this calculation to control the controlled object 2.

[0016]

As described above, according to the present invention, when a predetermined manipulated variable output is given to the controlled object, the time constant of the controlled object from the rising time until the measured value reaches a predetermined value lower than the set value. , PID constants are calculated by calculating characteristics such as waste time and so on, so it is only necessary to observe the response of the control amount in an extremely short time, the PID adjustment time can be greatly shortened, and the control operation can be immediately started. High accuracy and high response can be achieved. Further, since it is not necessary to repeat the on / off control for calculating the PID parameter constant, the operation end and the controlled object are not unnecessarily burdened with high reliability.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of signals of measured values according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control device 2 Control object 11 Measuring means 12 Characteristic calculating means 13 PID calculating means SV set value PV measured value (control amount) MV output (manipulation amount)

Claims (1)

[Claims] 1. A measuring means for measuring two times when a measured value reaches two predetermined values lower than a set value when a predetermined output is supplied to a controlled object, and based on the two times of the measuring means. A control device comprising a characteristic calculation means for calculating a time constant and a waste time of a controlled object, and a PID calculation means for calculating a PID constant based on an output value of the constant calculation.