Process control apparatus

Details Process control apparatus Process control apparatus

Filed on

1995-02-07

Date issued

1996-01-16

Examiner

Ruggiero, Joseph

Patent Class

Boots, shoes, and leggings

Other Related Categories

318561, 364161, 364162, 364177, G05B 1302

Type

Patent

Status

active

Patent number

054853672

Description

ABSTRACT:
A set point value SV(s) and a process value PV(s) are supplied to a deviation arithmetic operation circuit, and thereby a deviation E(s) is obtained. The deviation E(s) is input to a control arithmetic operation circuit, and at least a PI control arithmetic operation is executed to obtain a manipulative value MV(s) such that the deviation E(s) is set at zero. An disturbance D(s) is added to the manipulative value MV(s) and the result of the addition is supplied to the object to be controlled. A process value filter having a lead/lag time proportional to an integral time T.sub.I of the PI control arithmetic operation is inserted in a feedback line of the process value PV(s) to the deviation arithmetic operation circuit. The transfer function of the filter is (1+.alpha..multidot..beta..multidot.T.sub.I .multidot.s)/(1+.beta..multidot.T.sub.I .multidot.s). Although the optimal values of coefficients .alpha. and .beta. are 2.5 and 0.54, these values are variable in the range of 2 to 4 and the range of 0 to 1, respectively, depending on a first-order delay time T and a dead time L of the object. By setting .alpha. and .beta. in this way, the gain of the filter can be set at 1 at steady state and more than 1 at the transition state, so that both set point values following characteristic and disturbance suppression characteristics are improved.

REFERENCES:
patent: 4006346 (1977-02-01), Pemberton
patent: 4419729 (1983-12-01), Krieder
patent: 4489375 (1984-12-01), Putman
patent: 4755924 (1988-07-01), Hiroi
patent: 5043863 (1991-08-01), Bristol et al.
patent: 5195028 (1993-03-01), Hiroi

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