Bio-Inspired Pneumatic Modular Actuator for Peristaltic Transport

TL;DR

This work tackles the safe manipulation and transport of delicate or irregular objects by introducing a modular, soft, pneu matic peristaltic actuator system. It combines compression and longitudinal donut-shaped modules that stack into a station, enabling scalable peristaltic transport controlled through real-time pressure feedback. Key contributions include the geometrical optimization of multi-chamber rings, a dual-module design for gripping and axial transport, and a closed-loop, pressure-based synchronization strategy that scales across multiple levels. The results demonstrate robust handling of diverse objects with potential for underwater applications and integration with broader robotic platforms.

Abstract

While its biological significance is well-documented, its application in soft robotics, particularly for the transport of fragile and irregularly shaped objects, remains underexplored. This study presents a modular soft robotic actuator system that addresses these challenges through a scalable, adaptable, and repairable framework, offering a cost-effective solution for versatile applications. The system integrates optimized donut-shaped actuation modules and utilizes real-time pressure feedback for synchronized operation, ensuring efficient object grasping and transport without relying on intricate sensing or control algorithms. Experimental results validate the system`s ability to accommodate objects with varying geometries and material characteristics, balancing robustness with flexibility. This work advances the principles of peristaltic actuation, establishing a pathway for safely and reliably manipulating delicate materials in a range of scenarios.

Figures (6)

• Figure 1: Overview of the actuator's capability to grasp delicate and irregular objects, demonstrated using a fundamental unit (three stacks) for: (a) a bundle of marker pens, (b) a handheld tool (leveler), and a multi-level unit (five stacks) for (c) a fragile soft cuboid.
• Figure 2: Design of the actuation module. (a) The actuation ring (cross-sectional view) is donut-shaped with outer radius ($R$), inner radius ($r$), and multiple air chambers characterized by length ($s$), spacing ($l$), and wall thickness ($t$). Chambers are connected by air tunnels with step height ($m$). (b) The actuator station consists of a stack of different actuation modules. In longitudinal module, casing allows inflation along the top and bottom surfaces. For compression module, casing only allows inflation on the inner surface. (c) Finite element mesh of the ring.
• Figure 3: Fabrication process of the soft actuation ring. (a) Filling the mold with silicone material. (b) Eliminating air bubbles using a vacuum. (c) Solidifying the silicone. (d) Creating openings for connectors and tubing on the outer surface. (e) Connecting tubing to complete the assembly. (f) Repeating steps a and b with the upper mold, curing together with the completed bottom mold.
• Figure 4: Experimental setup. The actuator station integrates air pumps, air valves, pressure sensors, a microcontroller, and a computer, creating a closed-loop control system for actuator operation and data acquisition.
• Figure 5: Control of peristaltic locomotion. (a.1) Fundamental control module consisting of two compression modules positioned at the top and bottom, with a longitudinal module in the middle. (a.2) Control sequence to grasp object. (a.3) Control sequence to transport object. (b.1) The multi-level actuator station. (b.2) Multi-level synchronization based on pressure signal differences between the upper level, comparing scenarios with and without object grasp.