Towards a hierarchy of loco-manipulation affordances

We propose a formalism for the hierarchical representation of affordances. Starting with a perceived model of the environment consisting of geometric primitives like planes or cylinders, we define a hierarchical system for affordance extraction whose foundation are elementary power grasp affordances. Higher-level affordances, e.g. bimanual affordances, result from combining lower-level affordances with additional properties concerning the underlying geometric primitives of the scene. We model affordances as continuous certainty functions taking into account properties of the environmental elements and the perceiving robot's embodiment. The developed formalism is regarded as the basis for the description of whole-body affordances, i.e. affordances associated with whole-body actions. The proposed formalism was implemented and experimentally evaluated in multiple scenarios based on RGB-D camera data. The feasibility of the approach is demonstrated on a real robotic platform.