Self-tuning controller

Abstract

A controller in which proportional integral (PI) arithmetic is effected on a deviation between a measurement or process signal from a process or controlled system and a control set value, and a resultant manipulation signal is outputted to the process. A waveform of the process signal or the deviation signal is observed. PI arithmetic parameters undergo self-tuning so that the measurement result becomes a preset response target. In the preferred embodiment, means are provided for performing self-tuning on the PI arithmetic parameters including waveform observing means for using an area ratio of a first area to a second area as one of the evaluation indexes which represent patterns of the measured waveforms, the ratio being associated with the process signal or the deviation signal extending from a first generation timing of a first peak of the process signal or the deviation signal, to a subsequent second generation timing of a second peak, the second area being associated with the process signal or the deviation signal extending from the second generation timing to a timing given by second timing+(second timing - first timing).