A Back-Support Exoskeleton with a Cable-Driven Series-Parallel Elastic Actuation: Prototype Design and Operational Analysis

Wearable back-support exoskeletons can assist workers during heavy load lifting and lowering to reduce spinal loading. As these exoskeletons are worn by the user, they must be well designed to adapt to the natural movements of the human body. In this paper, the detailed design requirements of a back-support exoskeletons based on a biomechanical analysis of human bending motion is described. Following these requirements, a back-support exoskeleton with a novel cable-driven series parallel elastic actuation (SPEA) unit is proposed. A set of passive flexible elastic beams are used in parallel with an active cable-driven series-elastic actuator (CSEA) to lower the power and torque demand of the CSEA. Equipped with the proposed SPEA unit, the back-support exoskeleton interacts with human body only via flexible beams and cables. The possibility of misalignments or reduction of degrees of freedom of the body is minimized by the flexible interaction between human body and exoskeleton. Moreover, the design of the exoskeleton also permits the generation of axial twisting and lateral bending moments, which are key in supporting asymmetric lifting.