PID Self-Tuners: Some Theoretical and Practical Aspects

The appearance in the market of off-the-shelf PID self-tuning (PID/ST) controllers (see Cont. Eng., Oct. 1981) reflects the industry's need to satisfy increasingly stringent control objectives which can only be attained with adaptive algorithms. Further studies on the relatively mature adaptive control theory must be directed toward providing the field engineer with the fundamentals required to utilize this algorithm confidently and profitably. It is in this sense that the study of an adaptive version of the ubiquitous PID controller (with its unquestionably appealing characteristics) must be encouraged. This paper reviews the work done on PID/ST design, the major ideas are briefly discussed, and some specific algorithms presented. The performance of various PID/ST's is illustrated by simulated examples.