An Opposite-Bending-and-Extension Soft Robotic Manipulator for Delicate Grasping in Shallow Water

Abstract

Collecting seafood animals (such as sea cucumbers, sea echini, scallops, etc.) cultivated in shallow water (water depth: ∼30 m) is a profitable and an emerging field that requires robotics for replacing human divers. Soft robotics have several promising features (e.g., safe contact with the objects, lightweight, etc.) for performing such a task. In this paper, we implement a soft manipulator with an opposite-bending-and-extension structure. A simple and rapid inverse kinematics method is proposed to control the spatial location and trajectory of the underwater soft manipulator's end effector. We introduce the actuation hardware of the prototype, and then characterize the trajectory and workspace. We find that the prototype can well track fundamental trajectories such as a line and an arc. Finally, we construct a small underwater robot and demonstrate that the underwater soft manipulator successfully collects multiple irregular shaped seafood animals of different sizes and stiffness at the bottom of the natural oceanic environment (water depth: ∼10 m).

A Hybrid Jamming Structure Combining Granules and a Chain Structure for Robotic Applications

“…One of the challenges in soft robotics is that the soft robotic arms may not maintain their weight, since the soft-bodied system that has excessive softness and variable stiffness with limited operating radius has hardly been developed due to the limited stiffness tunable structure. 14,[30][31][32] The multilink hybrid jamming structure was demonstrated as a robotic arm for pickand-place task (Supplementary Video S5), as shown in Figure 10. A previously developed soft pneumatic gripper was assembled for the pick-and-place task.…”

For safe and compliant interaction: an outlook of soft underwater manipulators

“…56 The soft underwater arm in Figure 8(d) combines the bending and elongation segments and has been equipped to an AUV to grasp delicate objects in the shallow water. 57 Figure 8(e) shows the soft arms with bending and rotary modules which consists of two FRA with different fiber enwinding method. 58…”

“…(a) Six-DOF soft robot KAA. The frames are assigned at each joint in the zero configuration with red, green, and blue (RGB) axes corresponding to the XYZ axes, respectively 55 ; (b) the twisting actuator driven by vacuum 56 ; (c) the manipulator with two twisting joints and one bending segment 56 ; (d) the manipulator with two bending segments, one extension segment and a soft pneumatic gripper 57 ; and (e) the manipulator with bending and rotary modules. 58 …”

Robust passive tracking control for an uncertain soft actuator using robust right coprime factorization

“…In recent years, with the development of medical technology and the advent of an aging society, the research of soft actuators has been getting increasing attention, especially in the fields of minimally invasive surgery, biological shallow water harvesting, and auxiliary rehabilitation system, 1,2 wherein the soft actuator is generally made of a rubber material with low mechanical impedance and high safety for fragile objects. Various types of flexible actuators have been developed, especially pneumatic actuators, such as McKibben pneumatic artificial muscle flexible micro actuators, 3 a kind of pneumatic actuators to drive the movement of artificial arm, which is composed of inner rubber sleeve and outer double helix fiber woven layer.…”