Direct identification method of second order plus time delay model parameters

In this paper, we propose an identification method to estimate the second order plus time delay (SOPTD) model parameters. The proposed method directly obtains these parameters using a frequency-weighted integral transform and a least-squares method, without iterative calculation step. This calculation procedure can be applied regardless of initial states, in contrast to almost all previous identification methods, which require the assumption of zero initial states. In addition, it does not require any additional model reduction steps to tune the PID controller. Using simulations, it is demonstrated that the proposed method provides better modeling performance than previous methods, in spite of its simplicity. The new method shows an acceptable robustness to disturbance and measurement noise.