Affordances as a Framework for Robot Control

The concept of affordances, with its emphasis to the interactions between the robot and the environment, is highly relevant for epigenetic robotics. However, the use of the concept in robotics has been rather rudimentary, mostly confined to an inspiration source. In this paper, we present a new formalization of the concept, based partially on the recent formalizations proposed in Ecological Psychology and Linguistics, which provide a framework for robot control, learning and planning. We argue that affordances, as relations within the robotenvironment system, can be seen from three different perspectives; namely agent, observer and environmental. We argue that affordance relations can be learned from the interactions of the robot within its environment. The formalism argues that the interactions of the robot, can be represented as a nested triple of the form (effect, (entity, behavior)) indicating that the behavior applied in an environment perceived as the entity, would produce a perceivable effect. It is suggested that these nested triples of raw sensorymotor data obtained from different interactions can be used to form four different equivalence classes towards the formation of affordance relations. We present three studies implementing certain aspects of the formalism on a mobile robot moving in an environment filled with different types of objects. Specifically, we show that, (1) the formation of the entity equivalence classes corresponds to the perceptual learning of affordances, (2) the formation of effect equivalence classes, followed by the formation of entity equivalence classes can lead to the development of goal-directed behaviors from a set of primitive ones, and (3) the formed equivalence classes and relations provide support for planning and deliberation.