(Elsevier, 2023-04-13) Sánchez Moreno, José; Torre Cubillo, Luis de la; Chacón Sombría, Jesús; Dormido Canto, Sebastián; Elsevier; https://orcid.org/0000-0003-0898-3462
An event-based modification of the classical relay feedback experiment without the inclusion of additional elements (integrator, time delay, . . . ) for identification of the spectrum of stable processes between zero and the phase cross-over frequency is presented. By inserting an event-based sampler in the control loop, the natural behaviour of a classical relay is simulated and the system is forced to work in two modes. The event-based sampler activates the first mode by sending control actions to the process every time the error signal crosses zero; this mode is to discover the approximated value of the cross-over frequency ω180◦ . During the second mode, the event-based sampler sends samples to the process simulating that the error signal crosses zero at ω180◦ /N where N is the number of points to identify in the range 0 ≤ ω ≤ ω180◦ . One advantage of this procedure is that the logic used in an already existing relay feedback experiment to fit a transfer function model or tune a controller could be maintained just replacing the relay block by the event-based sampler block presented in the paper. Simulations and experiments with different processes and in presence of noise demonstrate the effectivity of the procedure.
