Development of an Anthropomorphic Soft Manipulator with Rigid-Flexible Coupling for Underwater Adaptive Grasping

Area of Science:

• Robotics and Mechanical Engineering
• Marine Technology
• Biomimetics

Background:

• Traditional rigid manipulators and pneumatic grippers have limitations in flexibility, adaptability, and grasping capabilities for complex underwater tasks.
• There is a need for advanced robotic systems inspired by biological structures to enhance underwater operations.
• Water hydraulics offer a promising actuation method for soft robotic systems, providing high power density and compliance.

Purpose of the Study:

• To propose and develop an anthropomorphic soft manipulator (ASM) driven by water hydraulics for underwater operations.
• To investigate the grasping capabilities, flexibility, adaptability, and load capacity of the ASM.
• To evaluate the performance of the ASM in both air and underwater environments, including handling delicate or unusually shaped objects.

Main Methods:

• Finite Element Modeling (FEM) was employed to simulate the linear elongation of bellows and the pitching performance of the ASM wrist.
• A mathematical model was established to describe the bending deformation of the water hydraulic soft gripper (WHSG).
• Experimental validation included FEM simulations and physical tests for bellows elongation, wrist pitching, gripper bending deformation, and contact forces, culminating in prototype fabrication and grasping experiments.

Main Results:

• The anthropomorphic soft manipulator (ASM) demonstrated superior grasping ability, flexibility, and adaptability compared to traditional rigid manipulators and pneumatic grippers.
• The ASM prototype successfully performed grasping tasks in air and underwater, adapting to various object shapes and dimensions by switching between standard and expanded grasping positions.
• The system showed harmless and effective capture of living animals (turtle, carp) and exhibited excellent adaptability to objects outside the standard grasping range or deviating from the center.

Conclusions:

• The developed water hydraulic anthropomorphic soft manipulator (ASM) is a highly capable and adaptable robotic system for underwater applications.
• The ASM's biomimetic design and water hydraulic actuation provide significant advantages for complex underwater manipulation, exploration, and sampling.
• The study confirms the enormous application potential and broader prospects of this novel soft manipulator in diverse underwater fields.