Soft Wrist Exosuit Actuated by Fabric Pneumatic Artificial Muscles

TL;DR

This paper introduces a lightweight soft wrist exosuit powered by fabric pneumatic artificial muscles, capable of controlling wrist movements with high torque, and presents a model for optimal design and motion control.

Contribution

The paper presents a novel lightweight wrist exosuit with fabric pneumatic muscles, including a torque model and motion control demonstrating improved performance.

Findings

Achieved a mean absolute torque error of 0.283 Nm

Peak torque of 3.3 Nm demonstrated

Limited range of motion compared to other designs

Abstract

Recently, soft actuator-based exosuits have gained interest, due to their high strength-to-weight ratio, inherent safety, and low cost. We present a novel wrist exosuit actuated by fabric pneumatic artificial muscles that has lightweight wearable components (160 g) and can move the wrist in flexion/extension and ulnar/radial deviation. We derive a model representing the torque exerted by the exosuit and demonstrate the use of the model to choose an optimal design for an example user. We evaluate the accuracy of the model by measuring the exosuit torques throughout the full range of wrist flexion/extension. We show the importance of accounting for the displacement of the mounting points, as this helps to achieve the smallest mean absolute error (0.283 Nm) compared to other models. Furthermore, we present the measurement of the exosuit-actuated range of motion on a passive human wrist. Finally, we demonstrate the device controlling the passive human wrist to move to a desired orientation along a one and a two-degree-of-freedom trajectory. The evaluation results show that, compared to other pneumatically actuated wrist exosuits, the presented exosuit is lightweight and strong (with peak torque of 3.3 Nm) but has a limited range of motion.