Passive Flow Control for Series Inflatable Actuators: Application on a Wearable Soft-Robot for Posture Assistance

TL;DR

This paper introduces a passive flow control method using 3D printed resistor tubes for series inflatable actuators, enabling sequential activation in soft robots, demonstrated on a wearable suit for postural assistance in infants with cerebral palsy.

Contribution

The study presents a novel passive flow control technique with 3D printed resistors for inflatable actuators, facilitating sequential activation from a single pressure source in soft robots.

Findings

Successful sequential control of inflatable actuators demonstrated

Effective application on a wearable robot-suit for postural assistance

Validation through tests with a dummy baby for upper-body motion control

Abstract

This paper presents a passive control method for multiple degrees of freedom in a soft pneumatic robot through the combination of flow resistor tubes with series inflatable actuators. We designed and developed these 3D printed resistors based on the pressure drop principle of multiple capillary orifices, which allows a passive control of its sequential activation from a single source of pressure. Our design fits in standard tube connectors, making it easy to adopt it on any other type of actuator with pneumatic inlets. We present its characterization of pressure drop and evaluation of the activation sequence for series and parallel circuits of actuators. Moreover, we present an application for the assistance of postural transition from lying to sitting. We embedded it in a wearable garment robot-suit designed for infants with cerebral palsy. Then, we performed the test with a dummy baby for emulating the upper-body motion control. The results show a sequential motion control of the sitting and lying transitions validating the proposed system for flow control and its application on the robot-suit.