Energy Optimal Humanoid Gait
Optimality of human locomotion and
energy-optimal control scheme for
biped robots
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Energy optimal gait of humanoid robots
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This work is done with Laurence Roussel and Carlos Canudas de Wit
from LAG-ENSIEG, Grenoble, France.
Imagine that you have designed a human-like biped robot and
its first task is to move on a straight line. How would you control
such a robot? With respect to this task of simple straight-line walk,
the biped robot is a highly redundant system -- it has many more
degrees of
freedom (joints) than are kinematically necessary to perform walking.
In order to specify the motions of the extra joints one may perhaps
formulate an optimal control problem based on either minimum time,
minimum joint travel, minimum power, or minimum energy. All these
criteria are reasonable but what if the resulting motion does not
appear human-like? Does human walk correspond to any optimal
criterion at all?
It has been conjectured that human locomotion optimizes calorific energy
per unit distance traveled although the energy surface is shallow
around the
minimum. Also conjectured, and perhaps more likely is the
possibility that if human locomotion is indeed optimal, it is
guided by a multi-criteria cost function. The available
literature on the optimality of human locomotion is rich
in theory and ingenious suggestions with very little decisive
experimental validation. Also not well-understood are the
effects of limb size, physical deformity on the optimal criteria.
Our work on a 4 dof planar biped robot model suggests that a
robot with anthropomorphic proportions (geometric and inertial)
may execute a natural swing phase almost passively.
This confirms the results of other researchers, both
in biomechanics and robotics. Our ongoing work seeks
optimal control schemes for a complete gait cycle, one
that includes the swing phase, the double support phase
and the crucial short-duration transition phases.
A list of my papers on this topic:
- Generation of energy-optimal
complete gait cycles for biped robots
- L. Roussel, C. Canudas de Wit, and A. Goswami
- IEEE Int. Conf. on Robotics and Automation,
Leuven, Belgium, May 1998.
- Periodic stabilization of a 1-dof hopping robot over nonlinear
compliant surface
- C. Canudas de Wit, L. Roussel, and A. Goswami
- IFAC Symp. on Robot Control (SyRoCo),
Nantes, France, September 1997.
- Comparative study of methods for energy-optimal gait generation for
biped robots
- C. Canudas de Wit, L. Roussel, and A. Goswami
- Int. Conf. on Informatics and Control,
St. Petersburg, Russia, June 1997.