Combining Morphological Interpolation and Biomechanical Inverse Kinematics to Simulate Bipedal Locomotion

N. Pronost, G. Nicolas, G. Dumont, and F. Multon (France)


Motion retargeting, Biomechanics, Morphological and multidimentional interpolations, Inverse kinematics.


The method presented in this paper aims at calculating a plausible bipedal locomotion based on anatomical data and biomechanical locomotor hypotheses. To this end, inverse kinematics and motion interpolation are used. In classi cal inverse kinematics approaches, the resolution of the pri mary task ensures that the effector follows a given trajec tory. This trajectory, considered in this work as the Carte sian displacement of the ankle as seen in the coordinate frame of the center of the pelvis, is computed using move ment adaptation and interpolation in a wide database. Ini tially, bipedal motions are captured thanks to a motion cap ture system and then, mathematically modeled. After the database is built, interpolation is performed according to three locomotor constraints: step length, spacing of the feet and reference posture of the character. In this paper, we include secondary tasks that enable to take biomechanical laws for bipedal locomotion into account: respecting joint limits, resembling a given reference posture and minimiz ing rotational kinetic energy. A weighted sum of the re sulting derivable cost functions enables us to select a spe cific solution in the null space of the primary task. After comparative validations related to biomechanical literature for bipedal locomotion (internal work, mechanical energy, jerk), we demonstrate that our method produces trajectories that are very close to captured ones.

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