We present a passive (unpowered) exoskeleton that assists the back during lifting. Our exoskeleton uses carbon fiber beams as the sole means to store energy and return it to the wearer. To motivate the design, we present general requirements for the design of a lifting exoskeleton, including calculating the required torque to support the torso for people of different weights and heights. We compare a number of methods of energy storage for exoskeletons in terms of mass, volume, hysteresis, and cycle life. We then discuss the design of our exoskeleton, and show how the torso assembly leads to balanced forces. We characterize the energy storage in the exoskeleton and the torque it provides during testing with human subjects. Ten participants performed freestyle, stoop, and squat lifts. Custom image processing software was used to extract the curvature of the carbon fiber beams in the exoskeleton to determine the stored energy. During freestyle lifting, it stores an average of 59.3 J and provides a peak torque of 71.7 Nm.

Research shows exoskeletons can reduce muscle activity and decrease the risk of injury for workers. Exoskeletons, therefore, are becoming more prevalent in industrial workplaces, and their use in some circumstances has already been mandated. It is probable that additional employers will mandate the use of exoskeletons as a means of mitigating injuries to their employees. This presents ethical concerns because employers hold power over the employees' wages and employment. Some employees who are required to wear exoskeletons may not be able to, while others may not wish to. How should workers' privacy and preferences be weighted? Should employees be prohibited from jobs that use exoskeletons if the exoskeletons do not fit them or if they do not wish to disclose their body's measurements? Should companies using exoskeletons be permitted to require workers to perform additional work with an exoskeleton? In this paper, we examine these and other ethical considerations related to mandatory exoskeleton use through the Six Pillars of Character framework of the Josephson Institute of Ethics ( 2002) and the Universal Moral Values for Corporate Codes of Ethics framework by Schwartz (2005). We provide a discussion of possible solutions following ethical tenets, including executing pilot studies before mandatory use policies, offering several self-adjustable models of exoskeletons, and allowing existing workers to transfer jobs if they are ill at ease with new exoskeleton policies. The best course of action may depend on specific individual circumstances.