Controlled in-plane locomotion of a hexapod using a single actuator

David Zarrouk, Ronald S. Fearing

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


This paper presents "1STAR," which is the first robot that is driven by a single actuator but can be directly commanded to move straight or turn clockwise or counterclockwise. The legged robot relies on a novel actuation gait, which exploits the compliance disparity between alternate stance tripods, to generate rotation by continuously accelerating and decelerating the legs. The direction of turning depends on the configuration of the legs - tripod left or right - and the timing of the acceleration and deceleration. Alternating leg acceleration in successive steps allows for continuous rotation in the desired direction. The turning radius can be varied by changing the timing of the leg acceleration and deceleration without changing the cycle frequency and linear speed. A simplified kinematic motion model of a robot is presented, and a dynamic simulation is performed to analyze the behavior and optimize robot parameters. The locomotion gait is verified experimentally using our newly designed "1STAR" robot.

Original languageEnglish
Article number7010029
Pages (from-to)157-167
Number of pages11
JournalIEEE Transactions on Robotics
Issue number1
StatePublished - 1 Feb 2015


  • Legged locomotion
  • mechanical intelligence
  • minimal actuation
  • robot control
  • robots

ASJC Scopus subject areas

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


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