Robust PID Controller Design for Plants with Delay Using Similarity Theory

Abstract Novel robust PID controller tuning is designed for second-order processes with varying delay in terms of the similarity theory. Similarity numbers are provided to characterize class of dynamically similar control loops enabling to tune all the robust PID controller settings together with a measurement filter adjustment. The novelty of the paper consists in the controller gain and filter constant settings by means of dominant four-pole placement such that the quadruple of placed poles is simultaneously robust. In addition these settings are generalized due to plant’s dynamics characteristics expressed by the similarity numbers that describe sets of dynamically similar plants considered stable. For proving the robust stability of the similar control loops an algorithm for the pseudospectral abscissa evaluation is applied. Finally an example of the stability proof is given.