K. Erbatur and U. Seven (Turkey)
Humanoid robots, locomotion, Zero Moment Point
The control of a biped humanoid is a difficult task due to
the hard-to-stabilize dynamics. Walking reference
trajectory generation is a key problem. Reference
generation techniques with the so-called Linear Inverted
Pendulum Model (LIPM) are reported. Improved versions
of the LIPM based reference generation are obtained by
applying the Zero Moment Point (ZMP) Criterion, widely
employed in the stability analysis of biped robot walk.
Typically, the ZMP reference during a stepping motion is
kept fixed in the middle of the supporting foot sole. This
kind of reference generation lacks naturalness, in that, the
ZMP in the human walk does not stay fixed, but it moves
under the supporting foot. This paper proposes a reference
generation algorithm based on single support foot ZMP
references which move in directions parallel and
perpendicular to the walking direction. A simple inverse
kinematics based independent joint position controller is
used in the full dynamics 3-D simulations with the model
of a 12 Degrees of Freedom (DOF) biped robot.
Simulation studies indicate that the moving ZMP
references result in a more successful walk.