Volume Transfer: A New Design Concept for Fabric-Based Pneumatic Exosuits

TL;DR

This paper introduces Volume Transfer, a novel design concept for fabric-based pneumatic exosuits that enhances wearability by concealing pneumatic components and increasing stress distribution, demonstrated through a knee extension assistive device.

Contribution

The work presents a new Volume Transfer design concept that improves the wearability and aesthetics of fabric-based pneumatic exosuits, validated by a prototype with optimized parameters.

Findings

The exosuit achieves 7.6Nm torque at 90kPa pressure.

The design reduces electromyography activity in knee extensor muscles.

The profile is only 26mm with half-leg stress coverage.

Abstract

The fabric-based pneumatic exosuit is now a hot research topic because it is lighter and softer than traditional exoskeletons. Existing research focused more on the mechanical properties of the exosuit (e.g., torque and speed), but less on its wearability (e.g., appearance and comfort). This work presents a new design concept for fabric-based pneumatic exosuits Volume Transfer, which means transferring the volume of pneumatic actuators beyond the garments profile to the inside. This allows for a concealed appearance and a larger stress area while maintaining adequate torques. In order to verify this concept, we develop a fabric-based pneumatic exosuit for knee extension assistance. Its profile is only 26mm and its stress area wraps around almost half of the leg. We use a mathematical model and simulation to determine the parameters of the exosuit, avoiding multiple iterations of the prototype. Experiment results show that the exosuit can generate a torque of 7.6Nm at a pressure of 90kPa and produce a significant reduction in the electromyography activity of the knee extensor muscles. We believe that Volume Transfer could be utilized prevalently in future fabric-based pneumatic exosuit designs to achieve a significant improvement in wearability.