Relay Based Identification for FOPDT System & Comparison on Measurement Accuracy & Sensitivity Analysis

This paper describes the identification with relay based of time delay system associated with the PID controller suitable parameters using the describing function (DF) method with analytical expression for system dynamics. Using unbiased (ideal) relay, it is easier to make out the disturbance at process input. Also comparable study of parameter accuracy between first order plus dead time (FOPDT) and second order plus dead time (SOPDT) and for extended to online identification, measurement sensitivity how much variation between relative error in time constant (T) and time delay (θ) with respect to the sustained oscillatory output cycle information such as maximum amplitude (Ap), critical frequency (W
_cr
). Simulate the standard system dynamics with static load disturbance. Examples are given to clarify the estimation accuracy in T, θ and measurement sensitivity across it.