Analysis of bend-over gesture wearing a trunk-support exoskeleton

In the context of industrial tasks, back exoskeletons aim at reducing operator’s muscular effort during the work gesture and prevent professional illnesses. Passive devices have the limitation of providing fixed support based on a single angle of bending kinematics. In this study, a multibody model previously validated was used to evaluate the biomechanical effects of assistance provided by passive exoskeletons in terms of joint actions. Specifically, the model, which involves the DOF allowed by the spine in the waist joint, reproduced experimental kinematics of two subjects realizing stoops and squats at various speeds. Kinematics was measured using an active exoskeleton prototype developed by the authors and inertial sensors (IMUs). Simulations revealed that passive assistance results in joint internal reactions mainly along the sagittal axis, which may lead to discomfort and instability in squat bending. Results underscore the importance of developing flexible laws for active systems able to adjust support dynamically to users’ movements and preferences.