Identification for integrating processes in the frequency domain

In this paper, a new identification method in the frequency domain from a relay-based test is proposed for integrating processes. In the relay test, only the very first period of oscillating input is implemented, which automatically results in a two-side pulse signal. The two-side pulse waveform contains enough larger spectrum magnitude over the important frequency range so that the process frequency responses can be accurately estimated at multiple points using the Fourier analysis method. Simulation examples are given to show both the effectiveness and practicality of the identification method for various integrating processes.