Virtual reference feedback tuning for two degree of freedom controllers using closed-loop step response data — Optimal pre-filter design in the frequency domain

The paper gives a Virtual Feedback Tuning (VRFT) for two degree of freedom controllers using closed-loop step response data in the frequency domain. While the original VRFT uses a data-driven performance index based on input/output data directly, the proposed one derives a frequency domain performance index based on the Fourier transformation of one-shot experimental input-output data. The frequency domain performance index makes the optimal pre-filter be straightforwardly designed without using the spectral density of the collected input signal. Hence, the proposed ones outperforms the original ones when the input and output data is collected from the closed loop step response. The effectiveness of the proposed method is illustrated through a numerical example.