Design and characterization of a multi-joint underactuated low-back exoskeleton for lifting tasks

Exoskeletons for industrial use are emerging to mitigate the risk of occurrence of work-related musculoskeletal diseases, such as low-back pain due to repetitive lifting activities. Yet, several factors are limiting the practical use of these devices in real-case scenarios, such as their weight and comfort. In this work, we describe iWear, an underactuated multi-joint exoskeleton for lifting applications. The key design feature of the device is the single actuation unit based on a Series-Elastic Actuation architecture, which drives three output joints, i.e. the left and right hips and the trunk. Moreover, passive degrees of freedom are designed to ensure the self-alignment of the robot with the user's trunk. Along with the presentation of the device, we report the performance of the actuation unit in torque control, which demonstrates to be fast and for the target application. The underactuated design of iWear holds promise for the design of wearable robots.