Closed-loop Relay Experiment for Modeling of Underdamped Plant Dynamics

The paper presents a setpoint weighted relay based modeling scheme for the identification of various industrial plants. Using asymmetrical and symmetrical relay settings with respect to a non-zero setpoint, simple mathematical expressions are derived for the assessment of each unknown parameters of a class of underdamped second order plus deadtime (SOPDT) plant dynamics. Thereafter, a real-time single-input single-output (SISO) water flow-line pressure control system is considered and identified in terms of underdamped SOPDT dynamics where an industrial standard platform is utilized for the arrangement of relay autotuning experiment. Finally, the efficacy of derived plant transfer function models is demonstrated through relay response in comparison with the models deduced from MATLAB in-built system identification toolbox.