Soft, Lightweight Wearable Robots to Support the Upper Limb in Activities of Daily Living: A Feasibility Study on Chronic Stroke Patients

Abstract

Stroke can be a devastating condition that impairs the upper limb and reduces mobility. Wearable robots can aid impaired users by supporting performance of Activities of Daily Living (ADLs). In the past decade, soft devices have become popular due to their inherent malleable and low-weight properties that makes them generally safer and more ergonomic. In this study, we present an improved version of our previously developed gravity-compensating upper limb exosuit and introduce a novel hand exoskeleton. The latter uses 3D-printed structures that are attached to the back of the fingers which prevent undesired hyperextension of joints. We explored the feasibility of using this integrated system in a sample of 10 chronic stroke patients who performed 10 ADLs. We observed a significant reduction of 30.3 ± 3.5% (mean ± standard error), 31.2 ± 3.2% and 14.0 ± 5.1% in the mean muscular activity of the Biceps Brachii (BB), Anterior Deltoid (AD) and Extensor Digitorum Communis muscles, respectively. Additionally, we observed a reduction of 14.0 ± 11.5%, 14.7 ± 6.9% and 12.8 ± 4.4% in the coactivation of the pairs of muscles BB and Triceps Brachii (TB), BB and AD, and TB and Pectoralis Major (PM), respectively, typically associated to pathological muscular synergies, without significant degradation of healthy muscular coactivation. There was also a significant increase of elbow flexion angle (12.1±1.5°). These results further cement the potential of using lightweight wearable devices to assist impaired users.

A Critical Review on Factors Affecting the User Adoption of Wearable and Soft Robotics

“… Illustrations of electric motor cable-driven soft wearables. ( A ) Noronha et al [ 51 ] describe their work on a tethered soft exosuit that comprises an elbow wearable and a hand exoskeleton. ( B ) Kim et al [ 42 ] describe their work on a tethered hip flexion exosuit which can reduce the metabolic rate of walking by up to 15.2%.…”

“…Efficient control of soft wearables is vital in operation because it directly affects user-machine interaction. Basic control schemes include the use of buttons [ 84 , 134 ], a smartphone [ 51 ], or a joystick [ 80 ] to conduct preprogrammed actions. Such control methodologies are mostly unintuitive and require a free hand to operate.…”

Wearable Robotics for Impaired Upper-Limb Assistance and Rehabilitation: State of the Art and Future Perspectives

“…EMG-control is often the adopted solutions for actuating the elbow, given this joint simple 1-DOF nature and the feasible access to the biceps and triceps muscles. Except for Nam et al [25] using an EMG-triggered NMES strategy to control the elbow or the wrist separately, and Noronha et al [146] using an impedance control at the elbow, all the other soft exosuits have been tested on individuals with a clinical condition by adopting a passive strategy. Figure 4 provides an overview of the main characteristics of the three types of systems -end-effectors, exoskeletons, exosuits -after having performed the research within the abovementioned databases.…”

Portable robots for upper-limb rehabilitation after stroke: a systematic review and meta-analysis

“…Preliminary results of a study by Noronha et al. [ 17 ] also show promising prospects in using flexible wearable devices for upper limb rehabilitation in stroke patients.…”