A Tendon-Driven Wrist Abduction-Adduction Joint Improves Performance of a 5 DoF Upper Limb Exoskeleton -- Implementation and Experimental Evaluation
Organizations: Neurorehabilitation Robotics and Engineering research group, Center for Rehabilitation Robotics, Department of Health Science and Technology, Aalborg University, Gistrup, Denmark · Department of Materials and Production, Aalborg University, Aalborg East, Denmark · Spinal Cord Injury Centre of Western Denmark, Regional Hospital of Viborg Denmark · Department of Clinical Medicine, Aarhus University, Denmark and Department of Brain Repair and Rehabilitation, UCL Queen Square Institute of Neurology, University College London, UK · Aalborg University Hospital, Department of Neurology, 9000 Aalborg, Denmark · Department of Architecture, Design and Media Technology, Aalborg University, Aalborg 9000, Denmark
Abstract
Wrist function is essential in performing activities of daily living (ADLs). However, there is limited experimental evidence on the functional impact of wrist Abduction-Adduction (Ab-Ad) joint assistance in upper limb exoskeletons (ULEs) for rehabilitation. This study evaluates the effect of implementing an active wrist Ab-Ad joint in a five degree of freedom (DoF) ULE, EXOTIC2 exoskeleton, to support individuals with severe motor impairments. Methods: A compact, lightweight wrist module with tendon-driven abduction and spring-driven adduction was integrated into the EXOTIC exoskeleton. Eight adults with no motor disabilities completed drinking and scratching tasks under randomized wrist-enabled and wrist-locked conditions along with a preliminary feasibility test in one individual with Amyotrophic lateral sclerosis (ALS). Kinematic and task performance metrics including wrist range of motion, task completion time, spillage and leveling metrics were assessed. Results: Implementing the wrist Ab-Ad DoF improved task success metrics. Spill incidence during the drinking task decreased from 56% to 3%, and leveling success for scratching task improved from 28% to 75%. Conclusion: Integrating wrist Ab-Ad assistance improved key functional task outcomes without increasing execution time. Significance: The study provides the experimental evidence that active wrist Ab-Ad control enhances task-level performance in exoskeleton-assisted ADLs.