Robust control of underactuated bipeds using sliding modes

Mehdi Nikkhah, Hashem Ashrafiuon, Farbod Fahimi

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The purpose of this paper is to present a robust tracking control algorithm for underactuated biped robots capable of self-balancing in the presence of external disturbances. The biped is modeled as a five-link planar robot with four actuators located at hip and knee joints. A sliding mode control law has been developed for the biped to follow a human-like gait trajectory while keeping the torso nearly upright. The control forces are calculated by defining four first-order sliding surfaces as a linear combination of the torso and the four joint tracking errors. The control approach is shown to guarantee that all trajectories will reach and stay on these surfaces during each step, while the walking cycle stability is maintained through a Lyapunov function. The criteria for asymptotic stability of the surfaces are presented and a numerical search method is implemented for the selection of the corresponding surface parameters. The paper further investigates the robustness of the controller in response to disturbances. Numerical simulations demonstrate the tracking stability of the biped's multistep walk and its human-like response to an external disturbance.

Original languageEnglish (US)
Pages (from-to)367-374
Number of pages8
JournalRobotica
Volume25
Issue number3
DOIs
StatePublished - May 2007
Externally publishedYes

Fingerprint

Robust control
Sliding Mode
Robust Control
Disturbance
Trajectories
Robots
Trajectory
Biped Robot
Force Control
Force control
Gait
Sliding mode control
Tracking Control
Sliding Mode Control
Lyapunov functions
Asymptotic stability
Robustness (control systems)
Search Methods
Walk
Balancing

Keywords

  • Biped robots
  • Sliding mode control
  • Stability analysis
  • Underactuated systems

ASJC Scopus subject areas

  • Control and Systems Engineering

Cite this

Robust control of underactuated bipeds using sliding modes. / Nikkhah, Mehdi; Ashrafiuon, Hashem; Fahimi, Farbod.

In: Robotica, Vol. 25, No. 3, 05.2007, p. 367-374.

Research output: Contribution to journalArticle

Nikkhah, Mehdi ; Ashrafiuon, Hashem ; Fahimi, Farbod. / Robust control of underactuated bipeds using sliding modes. In: Robotica. 2007 ; Vol. 25, No. 3. pp. 367-374.
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