Detail of publication

Abstract

PID pulse autotuner based on moments of the impulse response was already proved suitable for industrial practice. The new concept proposed in this paper relieves several weaknesses of the first autotuner generation. The autotuning procedure works with so called model set, which contains all processes satisfying both a priori assumption about the transfer function form and experimentally obtained characteristic numbers. It is assumed that the process is represented by multiple fractional-order pole transfer function. Further, it is supposed that first three moments of the process impulse response are obtained experimentally. For particular frequency, the model set processes create so called value set in frequency domain. In authors' previous work the analytical relations for computing value set boundary were given. It was shown that band of value sets is bounded by two extremal processes which are significant for consequential controller design. These two processes can be computed directly from the impulse response moments. Here, it is shown that the resulting band of frequency responses is larger comparing to the case when only integer-order processes are a priori assumed. The results are given for different values of the minimum allowed pole order. Moreover, it is explained how to equip the autotuner by a new user parameter ? specifying its robustness/ aggressiveness. The optimal PID controller parameters are computed as functions of normalized dead time and controller robustness ? for three modes of controller speed (SLOW / NORM / FAST).