@InProceedings{caron:humanoids:2016,
  author    = {Caron, St{\'e}phane and Kheddar, Abderrahmane},
  title     = {Multi-Contact Walking Pattern Generation Based on Model Preview Control of 3D COM Accelerations},
  booktitle = {IEEE-RAS International Conference on Humanoid Robots},
  year      = {2016},
  pages     = {550--557},
  address   = {Cancun, Mexico},
  month     = {November 15-November 17},
  url       = {https://hal.archives-ouvertes.fr/hal-01349880/document},
  keywords  = {Humanoid Locomotion, Multi-contact motion control, Preview Control},
  doi       = {10.1109/HUMANOIDS.2016.7803329},
  abstract  = {We present a multi-contact walking pattern generator based on preview-control of the 3D acceleration of the center of mass (COM). A key point in the design of our algorithm is the calculation of contact-stability constraints. Thanks to a mathematical observation on the algebraic nature of the frictional wrench cone, we show that the 3D volume of feasible COM accelerations is a always a downward-pointing cone. We reduce its computation to a convex hull of (dual) 2D points, for which optimal O(n log n) algorithms are readily available. This reformulation brings a significant speedup compared to previous methods, which allows us to compute time-varying contact-stability criteria fast enough for the control loop. Next, we propose a conservative \ast trajectory-wide\ast  contact-stability criterion, which can be derived from COM-acceleration volumes at marginal cost and directly applied in a model-predictive controller. We finally implement this pipeline and exemplify it with the HRP-4 humanoid model in multi-contact dynamically walking scenarios.}
}