Backdrivable and Fully-Portable Pneumatic Back Support Exoskeleton for Lifting Assistance

Abstract

To reduce the possibility of lower back pain (LBP), which is the most frequent injury in manual labor, several back support exoskeletons have been developed and implemented for lifting motion assistance. Although pneumatic power transmission is attractive due to its inherent compliance and backdrivability, the portability of the pneumatic system is highly limited due to the bulky air compressors that provide compressed air to the system. Therefore, we aimed to develop a fully-portable pneumatic back support exoskeleton by integrating all pneumatic components in the system. The compressed air consumption and generation of pneumatic system were modeled to meet design requirements. The developed exoskeleton was completely stand-alone and provides 80 Nm of maximum extension torque for 6 liftings per minute (6 l/m). The upper limit of the resistance torque was estimated to be about 2 Nm, which implies high backdrivability. Finally, lifting experiments were performed and surface electromyography (sEMG) was measured to validate the physical assistance of the developed exoskeleton system for ten subjects. Compared to the case with no exoskeleton, the back muscle activation was significantly reduced with the assistances.