ArmX: An Upper Extremity Exoskeleton Robot for Lift Assistance

Abstract

Work-related musculoskeletal disorders are most common among industrial workers due to repetitive handling of load by manual means. This paper proposes a seven degrees of freedom (DOF) robotic upper extremity exoskeleton named ArmX to provide lift assistance to reduce the risk of musculoskeletal injuries during manual handling. The device consists of shoulder and elbow units with three active DOF. The novel shoulder joint mechanism incorporated in the device allows the wearer to perform natural motions while delivering power assistance to shoulder flexion/extension and abduction/adduction with a single actuation system. ArmX also facilitates shoulder internal/external rotation, protraction/retraction and elevation/depression by passive means. Similarly, the mechanisms at the elbow and forearm provide power assistance for elbow flexion/extension and passively facilitate elbow supination/pronation. The proposed design has a greater level of manipulability for a compact and lightweight system. The power assistance ratios for the shoulder and elbow are 43% and 42% respectively. The functionality and performance of ArmX were evaluated both qualitatively and quantitatively using a fabricated prototype. The results of experiments verified the capability of the proposed exoskeleton to provide power assistance during lifting operations without restricting human-like motions.