An improved identification of low-order processes using relay feedback approach

Relay feedback approach plays prominent role for the identification of various lag-dominated processes in the process industries. A simple method is proposed for the identification of bench-marked practical examples. Relay with hysteresis is used as excitation signals in order to reduce the measurement noise in the identification process. Using the single symmetric relay test the parameters such as ultimate period (Pu) and ultimate gain (Ku) are estimated. From those two parameters a state space based analytical relations is developed to obtain the other model parameters accurately for efficient design and control the process. Simulink with MATLAB approach is adopted for carrying-out relay feedback test and related calculations. Different bench-marked examples are considered to illustrate the novelty of the proposed method. Combination of noise and load disturbances also considered in order to show the effectiveness of proposed method.