Control-oriented Modeling of Bend Propagation in an Octopus Arm

TL;DR

This paper introduces a control-oriented reduced order model for octopus arm bend propagation, capturing the complex mechanics and fluid interactions with a novel curvature parametrization, validated through simulations and experimental data.

Contribution

It presents a new reduced order model based on a novel curvature parametrization, simplifying complex dynamics for control purposes.

Findings

The reduced order model qualitatively matches computational simulations.

The model aligns well with experimental data.

Insights into bend propagation mechanisms are gained.

Abstract

Bend propagation in an octopus arm refers to a stereotypical maneuver whereby an octopus pushes a bend (localized region of large curvature) from the base to the tip of the arm. Bend propagation arises from the complex interplay between mechanics of the flexible arm, forces generated by internal muscles, and environmental effects (buoyancy and drag) from of the surrounding fluid. In part due to this complexity, much of prior modeling and analysis work has relied on the use of high dimensional computational models. The contribution of this paper is to present a control-oriented reduced order model based upon a novel parametrization of the curvature of the octopus arm. The parametrization is motivated by the experimental results. The reduced order model is related to and derived from a computational model which is also presented. The results from the two sets of models are compared using numerical simulations which is shown to lead to useful qualitative insights into bend propagation. A comparison between the reduced order model and experimental data is also reported.