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.
In a limit cycle autotuning method, the first limit cycle of alternately outputting a heat-side manipulated variable set point and a cool-side manipulated variable set point is generated. The first control response corresponding to the first limit cycle is detected. The second limit cycle is generated by changing one of the heat-side manipulated variable set point and the cool-side manipulated variable set point on the basis of predetermined change instruction information for instructing which one of the heat-side manipulated variable set point and the cool-side manipulated variable set point is to be changed after the first limit cycle and a predetermined manipulated variable change ratio indicating the degree of the change. The second control response corresponding to the second limit cycle is detected. The control parameter for each of the heat mode and the cool mode is calculated on the basis of the detected first and second control responses. A heat/cool control apparatus is also disclosed.
