Original Research ARTICLE
Learning and Acting in Peripersonal Space: Moving, Reaching, and Grasping
- 1University of Michigan, United States
The young infant explores its body, its sensorimotor system, and the immediately accessible parts of its environment, over the course of a few months creating a model of peripersonal space useful for reaching and grasping objects around it. Drawing on constraints from the empirical literature on infant behavior, we present a preliminary computational model of this learning process, implemented and evaluated on a physical robot.
The learning agent explores the relationship between the configuration space of the arm, sensing joint angles through proprioception, and its visual perceptions of the hand and grippers. The resulting knowledge is represented as the peripersonal space (PPS) graph, where nodes represent states of the arm, edges represent safe movements, and paths represent safe trajectories from one pose to another.
In our model, the learning process is driven by intrinsic motivation. When repeatedly performing an action, the agent learns the typical result, but also detects unusual outcomes, and is motivated to learn how to make those unusual results reliable. Arm motions typically leave the static background unchanged, but occasionally bump an object, changing its static position. The reach action is learned as a reliable way to bump and move a specified object in the environment.
Similarly, once a reliable reach action is learned, it typically makes a quasi-static change in the environment, moving an object from one static position to another. The unusual outcome is that the object is accidentally grasped (thanks to the innate Palmar reflex), and thereafter moves dynamically with the hand. Learning to make grasping reliable is more complex than for reaching, but we demonstrate significant progress.
Our current results are steps toward autonomous sensorimotor learning of motion, reaching, and grasping in peripersonal space, based on unguided exploration and intrinsic motivation.
Keywords: sensorimotor learning, autonomous robot learning, peripersonal space, reaching and grasping, intrinsic motivation, developmental robotics
Received: 11 Aug 2018;
Accepted: 04 Feb 2019.
Edited by:Matej Hoffmann, Faculty of Electrical Engineering, Czech Technical University in Prague, Czechia
Reviewed by:Lorenzo Jamone, Queen Mary University of London, United Kingdom
Elio Tuci, University of Namur, Belgium
Alessandro Roncone, University of Colorado Boulder, United States
Copyright: © 2019 Juett and Kuipers. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Mr. Jonathan Juett, University of Michigan, Ann Arbor, United States, firstname.lastname@example.org