Assist-As-Needed Exoskeleton for Hand Joint Rehabilitation Based on Muscle Effort Detection

• Main Authors: Jenny Carolina Castiblanco, Ivan Fernando Mondragon, Catalina Alvarado-Rojas, Julian D. Colorado
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Sensors
• Subjects: active control; robotic-assisted systems; EMG control; stroke rehabilitation; hand motion rehabilitation; hand exoskeleton orthosis
• Online Access: https://www.mdpi.com/1424-8220/21/13/4372

Robotic-assisted systems have gained significant traction in post-stroke therapies to support rehabilitation, since these systems can provide high-intensity and high-frequency treatment while allowing accurate motion-control over the patient’s progress. In this paper, we tackle how to provide active support through a robotic-assisted exoskeleton by developing a novel closed-loop architecture that continually measures electromyographic signals (EMG), in order to adjust the assistance given by the exoskeleton. We used EMG signals acquired from four patients with post-stroke hand impairments for training machine learning models used to characterize muscle effort by classifying three muscular condition levels based on contraction strength, co-activation, and muscular activation measurements. The proposed closed-loop system takes into account the EMG muscle effort to modulate the exoskeleton velocity during the rehabilitation therapy. Experimental results indicate the maximum variation on velocity was 0.7 mm/s, while the proposed control system effectively modulated the movements of the exoskeleton based on the EMG readings, keeping a reference tracking error <5%.