Online Identification of a Mechanical System in Frequency Domain Using Sliding DFT

• Published in: IEEE transactions on industrial electronics (1982) Vol. 63; no. 9; pp. 5712 - 5723
• Main Authors: Nevaranta, Niko, Derammelaere, Stijn, Parkkinen, Jukka, Vervisch, Bram, Lindh, Tuomo, Stockman, Kurt, Niemela, Markku, Pyrhonen, Olli, Pyrhonen, Juha
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Diagnostic systems; Discrete Fourier transforms; Dynamical systems; Dynamics; Estimation; Frequency domains; Mechanical systems; Monitoring; Nonparametric estimation; online identification; Real-time systems; Servocontrol; servomechanism; Sliding; sliding discrete Fourier transform (SDFT); Time domain techniques; Time-frequency analysis
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2016.2574303

A proper real-time system identification method is of great importance in order to acquire an analytical model that sufficiently represents the characteristics of the monitored system. While the use of different time-domain online identification techniques has been widely recognized as a powerful approach to system diagnostics, the frequency-domain identification techniques have primarily been considered for offline commissioning purposes. This paper addresses issues in the online frequency-domain identification of a mechanical system with varying dynamics; particular attention is paid to detect the changes in the system dynamics. A closed-loop online identification method is presented that is based on a sliding discrete Fourier transform at a selected set of frequencies. The method is experimentally validated by a closed-loop controlled servomechanism with a limited stroke and time-varying parameters.