On active reconstruction and compensation of harmonic disturbances with unknown frequencies

Abstract—In this work, a new robust control algorithm is introduced for uncertain systems subjected to harmonic disturbances with unknown frequencies. The proposed solution works under the framework of active disturbance rejection control (ADRC) and utilizes a specialized observer for sinusoidal uncertainties aided with a harmonic disturbance frequency estimator. The entire governing structure is derived in a convenient error based form, easily deployable across different industrial control software. The idea behind the introduced approach is general, but is conveyed here using solely a three degrees-of-freedom (3DOF) torsional system, which is well-known and representable model of vibration phenomenon in many mechanical systems. The efficacy of the proposed control scheme is validated with a set of experiments on a laboratory testbed and a rigorous stability analysis.