A control framework to generate nonenergy-storing virtual fixtures: Use of simulated plasticity

Ryo Kikuuwe, Naoyuki Takesue, Hideo Fujimoto

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


Some recent studies have addressed a class of human--machine coordination employing "virtual fixtures,"which are computer-generated walls or guides presented through haptic devices for assisting precise path tracing and for preventing the entry to specified regions. This paper presents the concept and control algorithms of a new class of virtual fixtures that is based on simulated plasticity. The plasticity-based virtual fixtures act as hard walls as long as the user's force is smaller than a predetermined yield force, but the user can deviate from the fixtures by intentionally producing a force larger than the yield force. As a characteristic of plasticity, the proposed virtual fixtures do not store elastic energy; the reaction force from the fixture almost always opposes the user's motion to decelerate the motion. Thus, the plasticity-based virtual fixtures are expected to be useful in some applications where safety is an utmost priority. This paper presents control algorithms for realizing the concept of plasticity-based virtual fixtures, addressing technical challenges in treating discontinuous nature of plasticity in discrete-time systems. The algorithms were demonstrated through experiments using impedance-type and admittance-type haptic devices.

Original languageEnglish
Pages (from-to)781-793
Number of pages13
JournalIEEE Transactions on Robotics
Issue number4
Publication statusPublished - Aug 2008

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Computer Science Applications
  • Electrical and Electronic Engineering


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