High-order variable-structure disturbance estimators with applications to harmonic drive systems

Yu Sheng Lu*, Chi Sheng Hwang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


This paper describes the design of a high-order variable-structure disturbance estimator (VSDE) that provides asymptotic estimation of unknown disturbances described by polynomial functions of time with arbitrary degrees. In comparison with conventional VSDEs, the high-order VSDE requires only a small switching gain for ensuring the existence of a sliding mode, thus alleviating the chattering problem. Moreover, the transfer function of a high-order VSDE from an unknown disturbance to its estimate can have a high relative degree to enable the estimation of time derivatives of an unknown disturbance while providing adequate high-frequency attenuation. Two high-order VSDEs were implemented to simultaneously observe the motor-side and the load-side disturbances in a harmonic drive system. Experimental results show that the compensation offered by the high-order VSDEs effectively deals with the disturbances induced by harmonic drive gearing.

Original languageEnglish
Pages (from-to)613-625
Number of pages13
JournalJournal of the Chinese Institute of Engineers, Transactions of the Chinese Institute of Engineers,Series A/Chung-kuo Kung Ch'eng Hsuch K'an
Issue number5
Publication statusPublished - 2009


  • Disturbance estimator
  • Harmonic drive
  • Sliding mode
  • Variable-structure systems

ASJC Scopus subject areas

  • General Engineering


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