In a control method, the first controlled variable is made to coincide with a
predetermined controlled variable set point. A relation variable representing the
relationship between second controlled variables which are designated in advance
from measured second controlled variables different from the first controlled variable
so as to maintain a predetermined relationship is calculated. A control actuator
is so controlled as to make the calculated relation variable coincide with a predetermined
relation variable set point. The difference between the calculated relation variable
and a relation variable set point corresponding to the calculated relation variable
is calculated. The calculated difference is added to the measured first controlled
variable. A manipulated variable is calculated by performing feedback control calculation
so as to make the sum coincide with the controlled variable set point. The calculated
manipulated variable is output to a corresponding control actuator. A control apparatus
is also disclosed.
