Kinematic modelling and design of a tendon actuated soft manipulator

Soft robots have garnered significant attention in recent years due to their ability to perform complex and organic motions, while being simple in structure. In particular, soft manipulators have enabled safer collaboration with humans and larger margins of error in applications such as grasping. Unfortunately, the lack of conventional mechanical joints and a large variety of designs necessitate the development of specialized kinematic models. In this paper, we present a novel mathematical framework for kinematic modelling of multi-section soft manipulators actuated by four pulling tendons per section embedded in an elastic, deformable material such as silicone. We use piecewise constant curvature approximation to capture the shape of the manipulator and derive an analytical forward kinematic mapping. Further, we accompany this model with a simple and effective numerical inverse kinematics approach. Finally, we develop a hardware prototype and perform a qualitative validation of both the forward and inverse kinematics. Our experiments indicate that this kinematic model is a feasible for the proposed robot design. Copyright (c) 2022 The Authors. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)