A Strong Underwater Soft Manipulator With Planarly-Bundled Actuators and Accurate Position Control

Abstract

Soft robotic manipulators have inherent advantages in underwater applications, as they generate motion by deforming seamless muscles rather than having rotational joints or sliding cylinders, as well as having excellent passive adaptability. However, limited by insufficient structural stiffness, achieving high payload and positioning accuracy remains challenging in existing soft manipulator designs. In this work, we propose an innovative approach to underwater soft manipulator design: 1) by constraining high- power optimized actuators with densely spaced lateral supporting plates, we could significantly enhance structural stiffness as well as improve the model accuracy drastically; 2) compaired with a novel flow-controllable open-circuit hydraulic actuation, we could keep the manipulator smoothly operated and depth-compensation-free; 3) in result, the manipulator could be modelled kinematically in a simplified way for position control. The entire workflow from mechanical design to actuation and control is presented. A prototype soft manipulator was developed to validate the proposed design experimentally.