Self-tuning PID controller using d-model identification

Abstract

This contribution presents an application of a self-tuning digital PID controller for process control modelled by d - models. The process is identified by the regression (ARX) model using the recursive least squares method (RLSM) with LD decomposition and applied directional forgetting. Controller synthesis is designed on the basis of a modified Ziegler-Nichols criterion for digital PID control loops. The ultimate (critical) proportional gain and period of oscillations have been derived for the second - order d - model. Control results using digital PID controller on the basic d - models and z - models are compared.