Identification of TITO Processes

Measurement noise and loop interaction introduces errors during the identification of a TITO process. This paper proposes a new method for estimation of the critical gains and the loop frequency of a TITO process. In the proposed structure, two preload relay (P-relay) are inserted in the feedback loops and two integral controllers are used in the process outputs. The method ensures a smooth limit cycle of the TITO process in the presence of measurement noise and loop interaction of various magnitudes. A pair of second order transfer function models for the TITO process dynamics is identified using the proposed identification method. Simulation results are given to illustrate the effectiveness of the proposed identification method.