Identification of over damped second order plus dead time process using relay feed back test

In this paper, a systematic approach is proposed for the structure identification and parameter estimation of over damped Second Order Plus Dead Time (SOPDT) process using relay feedback test. Exact analytical expressions are derived for the biased relay response of over damped SOPDT process. The parameters are estimated by applying boundary conditions obtained from the limit cycle data on the derived expressions. Then, the closed loop analysis is carried out using the estimated model. The proposed method is implemented in real time on two tank non interacting system.