A two-axis cable-driven ankle-foot mechanism

Evandro M. Ficanha, Mohammad Rastgaar, Kenton R. Kaufman

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


This paper describes a novel cable-driven ankle-foot mechanism with two controllable degrees of freedom (DOF) in dorsiflexion-plantarflexion (DP) and inversion-eversion (IE). The presented mechanism is a proof of concept to demonstrate feasibility. Ankle kinematic measurements demonstrate that ankle IE rotations during a step turn are significantly different from walking on a straight path. This suggests that the ankle-foot mechanisms used in prostheses, exoskeletons, and bipedal robots can be improved by controlling a second degree of freedom in the frontal plane. The proposed prototype mechanism is described in detail, and its design considerations and parameters are presented. The mechanism is capable of producing trajectories similar to the human ankle during a step turn. The device shows passive mechanical impedance close to the human ankle mechanical impedance, allowing its mechanical impedance to be controlled using an impedance controller. The presented mechanism is capable of providing key mechanical characteristics similar to the human ankle, including power, range of motion, and weight, suggesting the feasibility of this design concept.

Original languageEnglish (US)
JournalMathematische Zeitschrift
Issue number1
StatePublished - Nov 2 2014


  • Ankle impedance
  • Ankle mechanism
  • Ankle rotations
  • Cable-driven prosthesis
  • Human ankle kinematics
  • Multi-axis ankle-foot prosthesis
  • Powered lower extremity prosthesis
  • Turning
  • Two-DOF ankle-foot

ASJC Scopus subject areas

  • General Mathematics


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