On the explicit robust force control via disturbance observer

Emre Sariyildiz, Kouhei Ohnishi

Research output: Contribution to journalArticlepeer-review

105 Citations (Scopus)


This paper analyzes the robustness and stability of disturbance observer (DOb)-based explicit force control systems. Conventional analysis methods, which only consider ideal robustness, are impractical due to the design constraints of a DOb, e.g., bandwidth limitations. This paper shows that not only the stability but also the robustness of a DOb-based explicit force control system changes by environmental impedance variations. The robustness of a DOb-based explicit force control system is clarified by deriving new sensitivity functions. Implicit and explicit environmental impedance estimation methods are considered by analyzing the dynamics of a force sensor and a reaction force observer (RFOb), respectively. It is shown that the stability and performance of an explicit force control system can be improved by using an explicit environmental impedance estimation method, i.e., an RFOb, intrinsically. However, an RFOb is more sensitive than a force sensor to external disturbances, and the stability of the explicit force control system drastically changes by the design parameters of a DOb and an RFOb. Force-sensor- and RFOb-based explicit robust force control systems are compared in terms of stability, robustness, and performance in detail. The validity of the proposals is verified by simulation and experimental results.

Original languageEnglish
Article number6919295
Pages (from-to)1581-1589
Number of pages9
JournalIEEE Transactions on Industrial Electronics
Issue number3
Publication statusPublished - 2015 Mar 1
Externally publishedYes


  • Disturbance Observer
  • Explicit Force Control
  • Reaction Force Observer
  • Robust Control
  • Stability

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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