Wearable Extra Robotic Limb System With a Constant-Orientation Mechanism for the Handling of Construction Material

A wearable extra robotic limb (XRL) system is a wearable robotic system that directly assists in handling materials and tools, differentiating it from exoskeleton robots, which tend to directly support the joints. XRL systems thus hold promise for the prevention of work-related musculoskeletal disorders (WMSDs) among construction workers. However, there is a lack of specific designs for construction tasks. Therefore, this paper analyzes a workpiece handling task to derive operating mechanisms and design parameters for an XRL system that can provide sufficient assistance. The proposed design aims to provide the worker with constant orientation for intuitive tasks, thus eliminating unnecessary elements and reducing the burden on the wearer. A finite state machine algorithm is also employed to convey the worker’s intent when handling a workpiece, enabling intuitive collaboration. To validate the proposed design, two experiments are conducted, with the results demonstrating that the use of the robotic system effectively assists the wearer with tasks and reduces musculoskeletal strain, thus reducing the risk of WMSDs.