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arXiv · 1709.03660

Straight-Leg Walking Through Underconstrained Whole-Body Control

Robert J. Griffin·Georg Wiedebach·Sylvain Bertrand·Alexander Leonessa·Jerry Pratt
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Abstract

We present an approach for achieving a natural, efficient gait on bipedal robots using straightened legs and toe-off. Our algorithm avoids complex height planning by allowing a whole-body controller to determine the straightest possible leg configuration at run-time. The controller solutions are biased towards a straight leg configuration by projecting leg joint angle objectives into the null-space of the other quadratic program motion objectives. To allow the legs to remain straight throughout the gait, toe-off was utilized to increase the kinematic reachability of the legs. The toe-off motion is achieved through underconstraining the foot position, allowing it to emerge naturally. We applied this approach of under-specifying the motion objectives to the Atlas humanoid, allowing it to walk over a variety of terrain. We present both experimental and simulation results and discuss performance limitations and potential improvements.

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Robert J. Griffin, Georg Wiedebach, Sylvain Bertrand, Alexander Leonessa, Jerry Pratt. 2017-09-12. Straight-Leg Walking Through Underconstrained Whole-Body Control. https://doi.org/10.1109/icra.2018.8460751

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