Preliminary Analysis and Design of a Passive Upper Limb Exoskeleton

This article reports the preliminary analysis and design of a novel 6 degrees of freedom, passive, upper limb exoskeleton for industrial applications. The aim is to conceive a wearable device to support workers in a vast range of repetitive tasks, offering an effective strategy to reduce the risk of injuries in production lines. The exoskeleton primary purpose is to compensate for the gravity loads acting on the human upper limb via the action of five springs. By reaching the static balancing through the use of passive elements only, several advantages in terms of reduced weight and cost can be provided. In this scenario, a detailed analytical approach has been developed to study the exoskeleton statics and synthesize the springs within the human upper limb workspace. In particular, a 3R balancer is designed for the exoskeleton shoulder joint and a set of computationally efficient optimization studies are carried out to determine the optimal coefficients and positions of the springs. The obtained results have been validated with a commercial multibody tool.