Nonlinear oscillations for cyclic movements in human and robotic arms

Dominic Lakatos, Florian Petit, Alin Albu-Schäffer

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The elastic energy storage in biologically inspired variable impedance actuators (VIA) offer the capability of executing cyclic and/or explosive multi-degree of freedom (DoF) motions efficiently. This paper studies the generation of cyclic motions for strongly nonlinear underactuated multi-DoF serial robotic arms. By experimental observations of human motor control, a simple and robust control law is deduced. This controller achieves intrinsic oscillatory motions by switching the motor position triggered by a joint torque threshold. Using the derived controller, the oscillatory behavior of human and robotic arms is analyzed in simulations and experiments. It is found that the existence of easily excitable oscillation modes strongly depends on the damping properties of the plant. If the intrinsic damping properties are such that oscillations excited in the undesired modes decay faster than in the desired mode, then multi-DoF oscillations are easily excitable. Simulations and experiments reveal that serially-structured elastic multibody systems such as VIA or human arms with approximately equal joint damping, fulfill these requirements.

Original languageEnglish
Article number6778046
Pages (from-to)865-879
Number of pages15
JournalIEEE Transactions on Robotics
Volume30
Issue number4
DOIs
StatePublished - Aug 2014

Keywords

  • Biologically inspired robots
  • motion control
  • nonlinear oscillations
  • underactuated robots
  • variable impedance actuators (VIA)

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