We present a physically-based system to simulate and control the
locomotion of soft body characters without skeletons. We use the
finite element method to simulate the deformation of the soft body,
and we instrument a character with muscle fibers to allow it to actively control its shape. To perform locomotion, we use a variety of
intuitive controls such as moving a point on the character, specifying the center of mass or the angular momentum, and maintaining
balance. These controllers yield an objective function that is passed
to our optimization solver, which handles convex quadratic program
with linear complementarity constraints. This solver determines the
new muscle fiber lengths, and moreover it determines whether each
point of contact should remain static, slide, or lift away from the
floor. Our system can automatically find an appropriate combination of muscle contractions that enables a soft character to fulfill
various locomotion tasks, including walking, jumping, crawling,
rolling and balancing.
We thank the anonymous reviewers for their helpful comments. We
thank Yuting Gu for modeling, rendering and video editing. We
also thank Yuting Ye for her suggestions and all other members of
Gatech Graphics Lab for their help on this work. This work was
funded by NSF CCF-811485, IIS-11130934 and Alfred P. Sloan
Foundation.