title: Measuring information transfer in a soft robotic arm.
abstract: Soft robots can exhibit diverse behaviors with simple types of actuation by partially outsourcing control to the morphological and material properties of their soft bodies, which is made possible by the tight coupling between control, body, and environment. In this paper, we present a method that will quantitatively characterize these diverse spatiotemporal dynamics of a soft body based on the information-theoretic approach. In particular, soft bodies have the ability to propagate the effect of actuation through the entire body, with a certain time delay, due to their elasticity. Our goal is to capture this delayed interaction in a quantitative manner based on a measure called momentary information transfer. We extend this measure to soft robotic applications and demonstrate its power using a physical soft robotic platform inspired by the octopus. Our approach is illustrated in two ways. First, we statistically characterize the delayed actuation propagation through the body as a strength of information transfer. Second, we capture this information propagation directly as local information dynamics. As a result, we show that our approach can successfully characterize the spatiotemporal dynamics of the soft robotic platform, explicitly visualizing how information transfers through the entire body with delays. Further extension scenarios of our approach are discussed for soft robotic applications in general.
authors.affiliation: The Hakubi Center for Advanced Research, Kyoto University, 606-8501 Kyoto, Japan. Department of Applied Analysis and Complex Dynamical Systems, Graduate School of Informatics, Kyoto University, 606-8501 Kyoto, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakajima
authors.forename: N
authors.initials: N
authors.lastname: Schmidt
authors.forename: R
authors.initials: R
authors.lastname: Pfeifer
mesh_terms: D000818:Animals; D032701:Biomimetics / Q000379:methods*; D003198:Computer Simulation; D055119:Elastic Modulus; D005121:Extremities / Q000502:physiology*; D016247:Information Storage and Retrieval / Q000379:methods*; D008954:Models, Biological; D049831:Octopodiformes / Q000502:physiology*; D012371:Robotics / Q000295:instrumentation* / Q000379:methods*