Design methodology of an active back-support exoskeleton with adaptable backbone-based kinematics

Abstract Manual labor is still strongly present in many industrial contexts (such as aerospace industry). Such operations commonly involve onerous tasks requiring to work in non-ergonomic conditions and to manipulate heavy parts. As a result, work-related musculoskeletal disorders are a major problem to tackle in workplace. In particular, back is one of the most affected regions. To solve such issue, many efforts have been made in the design and control of exoskeleton devices, relieving the human from the task load. Besides upper limbs and lower limbs exoskeletons, back-support exoskeletons have been also investigated, proposing both passive and active solutions. While passive solutions cannot empower the human's capabilities, common active devices are rigid, without the possibility to track the human's spine kinematics while executing the task. The here proposed paper describes a methodology to design an active back-support exoskeleton with backbone-based kinematics. On the basis of the (easily implementable) scissor hinge mechanism, a one-degree of freedom device has been designed. In particular, the resulting device allows tracking the motion of a reference vertebra, i.e., the vertebrae in the correspondence of the connection between the scissor hinge mechanism and the back of the operator. Therefore, the proposed device is capable to adapt to the human posture, guaranteeing the support while relieving the person from the task load. In addition, the proposed mechanism can be easily optimized and realized for different subjects, involving a subject-based design procedure, making possible to adapt its kinematics to track the spine motion of the specific user. A prototype of the proposed device has been 3D-printed to show the achieved kinematics. Preliminary tests for discomfort evaluation show the potential of the proposed methodology, foreseeing extensive subjects-based optimization, realization and testing of the device

The Asymmetric Back Exosuit: Design, Realization, and Biomechanical Evaluation

Musculoskeletal disorders of the back are an extremely prevalent health issue across the workforce in the United States. This is especially a concern in industries involving manual materials handling tasks that cause low back pain. While these injuries are generated by both symmetric and asymmetric lifting, asymmetric movements are often more damaging. Exoskeleton technology has become an increasingly popular preventative measure to low back pain, but many devices do not assist in asymmetry. Thus, I present a new system called the Asymmetric Back Exosuit (ABX). The ABX addresses this important gap in the field through unique design geometry and active cable-driven actuation. The suit allows the user to move in a wide range of lumbar trajectories while the “X” pattern cable routing allows for variable assistance application for these trajectories, enabling assistance during asymmetric movements. As indicated by a biomechanical model of the system made in OpenSim, the cable forces can be mapped to effective lumbar torque assistance for a given lumbar trajectory, allowing for intuitive controller design over the complex kinematic chain for varying lifting techniques. An early human subject study indicated that the ABX was able to reduce low back muscle activation during symmetric and asymmetric lifting by an average of 37.8% and 16.0%, respectively, compared to lifting without the exosuit. This was expanded to a larger biomechanics study of the ABX for which preliminary results of three subjects are examined and discussed. These evaluations indicate the potential for the ABX to reduce lumbar injury risk during symmetric and asymmetric manual materials handling tasks.M.S