Fall Initiation Criteria for Three-Dimensional Multi-Segmental Model of Biped Robot

A biped mechanism can maintain its balance by redirecting the ground reaction force direction and changing the center of pressure location. In this paper, how the variable inertia in a multibody dynamic model is related to those efforts is investigated and fall initiation criteria in three dimensional space, a balanced state manifold is constructed by using a 3D multi-segmental model. The balanced state domain is constructed by iteratively solving nonlinear constrained optimization problems and finding the velocity extrema at given center of mass positions subjected to certain balancing conditions. The constructed balanced state domain of a multi-segmental model can be used as fall initiation criteria in 3D space and it demonstrates the better balancing maintenance capability of 3D multi-segmental model than the 3D linear inverted pendulum mode.