Model-Based Control of Soft Robots: A Survey of the State of the Art and Open Challenges

TLDR

Continuum soft robots are entirely deformable mechanical systems designed to emulate soft biological appendages, yet the field faces challenges from diverse terminology, varied scientific backgrounds, and unclear distinctions between immature technology limits and intrinsic robotic challenges. The study introduces a control‑theoretic perspective to soft robotics and seeks to lower entry barriers by presenting existing results, future challenges, and key intrinsic effects—continuum dynamics, elastic potentials, and variable sensing/actuation—within a unified framework. The authors adopt a unified language and coherent framework to present existing results and future challenges, emphasizing intrinsic effects such as continuum dynamics, elastic potentials, and variable sensing/actuation.

Abstract

Continuum soft robots are mechanical systems entirely made of continuously deformable elements. This design solution aims to bring robots closer to invertebrate animals and soft appendices of vertebrate animals (e.g., an elephant's trunk, a monkey's tail). This work aims to introduce the control theorist perspective to this novel development in robotics. We aim to remove the barriers to entry into this field by presenting existing results and future challenges using a unified language and within a coherent framework. Indeed, the main difficulty in entering this field is the wide variability of terminology and scientific backgrounds, making it quite hard to acquire a comprehensive view on the topic. Another limiting factor is that it is not obvious where to draw a clear line between the limitations imposed by the technology not being mature yet and the challenges intrinsic to this class of robots. In this work, we argue that the intrinsic effects are the continuum or multi-body dynamics, the presence of a non-negligible elastic potential field, and the variability in sensing and actuation strategies.