Zero Step Capturability for Legged Robots in Multicontact

A. Del Prete, S. Tonneau, N. Mansard

Research output: Contribution to journalArticlepeer-review

Abstract

The ability to anticipate a fall is fundamental for any robot that has to balance. Currently, fast fall-prediction algorithms only exist for simple models, such as the linear inverted pendulum model (LIPM), whose validity breaks down in multicontact scenarios (i.e., when contacts are not limited to a flat ground). This paper presents a fast fall-prediction algorithm based on the point-mass model, which remains valid in multicontact scenarios. The key assumption of our algorithm is that, in order to come to a stop without changing its contacts, a robot only needs to accelerate its center of mass in the direction opposite to its velocity. This assumption allows us to predict the fall by means of a convex optimal control problem, which we solve with a fast custom algorithm (less than 11 ms of computation time). We validated the approach through extensive simulations with the humanoid robot HRP-2 in randomly-sampled scenarios. Comparisons with standard LIPM-based methods demonstrate the superiority of our algorithm in predicting the fall of the robot, when controlled with a state-of-the-art balance controller. This paper lays the foundations for the solution of the challenging problem of push recovery in multicontact scenarios.
Original languageEnglish
Pages (from-to)1021-1034
Number of pages14
JournalIEEE Transactions on Robotics
Volume34
Issue number4
DOIs
Publication statusPublished - 1 Aug 2018

Keywords / Materials (for Non-textual outputs)

  • humanoid robots
  • legged locomotion
  • optimal control
  • pendulums
  • robot dynamics
  • zero step capturability
  • legged robots
  • fast fall-prediction algorithm
  • multicontact scenarios
  • point-mass model
  • fast custom algorithm
  • humanoid robot HRP-2
  • randomly-sampled scenarios
  • linear inverted pendulum model
  • convex optimal control problem
  • LIPM-based methods
  • Legged locomotion
  • Prediction algorithms
  • Humanoid robots
  • Minimization
  • Friction
  • Acceleration
  • Legged robots
  • multicontact
  • stability
  • viability

Fingerprint

Dive into the research topics of 'Zero Step Capturability for Legged Robots in Multicontact'. Together they form a unique fingerprint.

Cite this