Self-discovery of motor primitives and learning grasp affordances

Abstract

Human infants practice their initial, seemingly random arm movements for transforming them into voluntary reaching and grasping actions. With the developing perceptual abilities, infants further explore their environment using the behavior repertoire they have developed, and learn causality relations in the form of affordances, which they use for goal satisfaction and motor planning. This study proposes and implements a developmental progression on a robotic system mimicking the aforementioned infant development stages: An anthropomorphic robot hand with one basic action of swing-hand and the palmar reflex (i.e. the enclosure of the fingers upon contact) at its disposal, executes swing-hand action targeted to a salient object with different hand speeds. During the executions, it monitors the changes in its sensors, automatically forming behavior primitives such as `grasp', `hit', `carry-object' and `drop' by segmenting and differentiating the initial swing-hand action. The study then focuses on one of these behaviors, namely grasping, and shows how further practice allows the robot to learn affordances of more complex objects, which can be further used to make plans to achieve desired goals using the discovered behavior repertoire.