Robust estimation of process frequency response from relay feedback

Abstract A method for the robust process frequency response estimation in the presence of noise and disturbance is proposed. The effect of noise on the identification results is suppressed with the application of the familiar averaging technique to the input–output samples collected from the limit cycles exhibited in relay feedback tests, while the effect of linear disturbances is removed by conducting multiple relay tests. Simulations are performed to verify the capability of the method through the identification of a simple first order plus dead time process.