Nonlinear Modes as a Tool for Comparing the Mathematical Structure of Dynamic Models of Soft Robots

Pietro Pustina, Davide Calzolari, Alin Albu-Schaffer, Alessandro De Luca, Cosimo Della Santina

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Continuum soft robots are nonlinear mechanical systems with theoretically infinite degrees of freedom (DoFs) that exhibit complex behaviors. Achieving motor intelligence under dynamic conditions necessitates the development of control-oriented reduced-order models (ROMs), which employ as few DoFs as possible while still accurately capturing the core characteristics of the theoretically infinite-dimensional dynamics. However, there is no quantitative way to measure if the ROM of a soft robot has succeeded in this task. In other fields, like structural dynamics or flexible link robotics, linear normal modes are routinely used to this end. Yet, this theory is not applicable to soft robots due to their nonlinearities. In this work, we propose to use the recent nonlinear extension in modal theory -called eigenmanifolds- as a means to evaluate control-oriented models for soft robots and compare them. To achieve this, we propose three similarity metrics relying on the projection of the nonlinear modes of the system into a task space of interest. We use this approach to compare quantitatively, for the first time, ROMs of increasing order generated under the piecewise constant curvature (PCC) hypothesis with a high-dimensional finite element (FE)-like model of a soft arm. Results show that by increasing the order of the discretization, the eigenmanifolds of the PCC model converge to those of the FE model.

Original languageEnglish
Title of host publication2024 IEEE 7th International Conference on Soft Robotics, RoboSoft 2024
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages779-785
Number of pages7
ISBN (Electronic)9798350381818
DOIs
StatePublished - 2024
Event7th IEEE International Conference on Soft Robotics, RoboSoft 2024 - San Diego, United States
Duration: 14 Apr 202417 Apr 2024

Publication series

Name2024 IEEE 7th International Conference on Soft Robotics, RoboSoft 2024

Conference

Conference7th IEEE International Conference on Soft Robotics, RoboSoft 2024
Country/TerritoryUnited States
CitySan Diego
Period14/04/2417/04/24

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