Authors:
Zhongkai Chen
1
;
Nafissa El Yaaqoubi
2
and
Gabriel Abba
3
Affiliations:
1
Arts et Métiers ParisTech, France
;
2
ENIM, France
;
3
Design Manufacturing Control Lab and ENIM, France
Keyword(s):
Biped Robot, Optimal Walk, Segmented Torso, Zero Dynamics, Energy Efficiency.
Related
Ontology
Subjects/Areas/Topics:
Humanoid Robots
;
Informatics in Control, Automation and Robotics
;
Robot Design, Development and Control
;
Robotics and Automation
Abstract:
Recently, underactuated bipeds with pointed feet have been studied to achieve dynamic and energy efficient
robot walking patterns. However, these studies usually simplify a robot torso as one link, which is different
from a human torsos containing 33 vertebrae. In this paper, therefore, we study the optimal walking of a 6-link
planar biped with a segmented torso derived from its 5-link counterpart while ensuring that two models are
equivalent when the additional torso joint is locked. For the walking, we suppose that each step is composed
of a single support phase and an instantaneous double support phase, and two phases are connected by a
plastic impact mapping. In addition, the controlled outputs named symmetry outputs capable of generating
exponentially stable orbits using hybrid zero dynamics, are adopted to improve physical interpretation. The
desired outputs are parameterized by Bézier functions, with 5-link robot having 16 parameters to optimize
and 6-link robot havin
g 19 parameters. According to our energy criterion, the segmented torso structure may
reduce energy consumption up to 8% in bipedal walking, and the maximum energy saving is achieved at high
walking speeds, while leaving the criteria at low walking speeds remain similar for both robots.
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