In this paper, a general procedure for identifying fractional first-order plus dead-time (FFOPDT) model is presented. This based on fitting three arbitrary points the process reaction curve, where information obtained from simple open-loop test. A simplification of identification also considered, only symmetrically located curve are selected. The proposed symmetrical has been applied to followi...

This paper compares the frequency domain performance criterion (Jv) of PI, fractional PI, and PID controllers when a step load disturbance is applied at the plant input. Process information is available in form of first-order plus dead-time (FOPDT) model. In addition, the controllers were compared using the H∞–norm of the sensitivity function as a measure of robustness, and some comments on ind...

Unknown process parameters are identified using limit cycle data of the relay–response curves obtained from single relay feedback test on second order plus dead time (SOPDT) processes. Time domain analytical expressions of these curves are helpful in deriving conditions to estimate process parameters accurately. Identification algorithms are formulated to estimate minimal number of model parame...

This paper deals with the stability of an event-based proportional-integral controller. In particular, necessary and sufficient conditions on the controller parameters for the existence of equilibrium points without limit cycles are given for a first-order-plus-dead-time process. Practical issues related to the controller implementation are also addressed. The presented conditions enable a simp...

In this paper we discuss the use of a noncausal approach for the improvement of PID control, according to a method presented in (Piazzi and Visioli, 2004). In particular we verify that, despite the proposed methodology is based on an estimated first-order plus dead time (FOPDT) model of the process, different identification procedure can be employed for this purpose yielding in any case to a go...

The paper deals with approximation of systems with the dominant first order dynamics by the Integrator Plus Dead Time (IPDT) model based on the analysis of the nonsymmetrical oscillations with possible offset arising typically under relay control. The analytical derivation is illustrated by results achieved by identification of optical plant. The results are experimentally verified by PI contro...