Embodied basis of invariant features in execution and perception of whole-body dynamic actions - knacks and focuses of Roll-and-Rise motion

This paper attempts to discover the invariant features in a whole-body dynamic task under perturbations. Our hypothesis is that the features are useful both for execution and recognition of a task, and have their origin in human embodiment. For the sake of concreteness, we focus on a particular task named Roll-and-Rise motion, and carried out a multi-approach investigation. First, an analysis of motion capture data of human performance is presented to show its invariant features. Next, we show that such invariants emerge from the underlying physics of the task, using simulation data. These invariants are actually useful for generating robot motion, which has been successfully realized with an adult-size real humanoid robot. The experimental data are analyzed to confirm the temporal localization of invariant features. Lastly, we present a psychological experiment which confirms that these timings are actually important points where human observers extract crucial information about the task. (C) 2004 Elsevier B.V. All rights reserved.