An Integrated Approach to Exoskeleton Device Evaluation and Design

Abstract

Industrial sectors where manual tasks are the primary job responsibilities continue to report a high prevalence of work-related musculoskeletal disorders (WMSDs). Sustained repetitive motion and non-neutral postures are among many of the known biomechanical risks for the development of WMSD. Established engineering and administrative control methods exist to modulate the risks; however, these methods might become less effective or cost-prohibitive in complex and dynamic work environments. In recent years, exoskeleton devices have begun to rapidly appear across industries as a form of worker protection for a variety of tasks and environments. Although these devices show promising potential, it is generally agreed that substantially more research in exoskeleton evaluation and design is needed before a wide implementation can be universally endorsed. This dissertation introduces an integrated approach that combines aspects of ergonomic observations, exoskeleton design, and biomechanical exoskeleton evaluation. First, a combination of ergonomic observation methods was utilized to identify potential biomechanical risks and to evaluate the applicability of exoskeleton devices at two participating work sites. Using an estimated threshold value, it was assessed that both work sites might benefit from the use of exoskeleton devices. Second, the design and development of an exoskeleton device were introduced and subsequently, a new framework for a second-generation device with improvements toward kinematic compliance, anthropometric fit, modularity, potential for reduction of hand-arm vibration exposures, and operation and control methods was presented. Lastly, a total of five exoskeleton devices were evaluated in two experiments that were designed to mimic body postures and replicate scenarios seen during the earlier ergonomic observations. Several devices demonstrated the ability to reduce muscle activity in their supported muscle groups, whereas others did not perform as expected while also inducing slight postural and movement alterations. The integrated approach introduced in this dissertation utilized ergonomic observations to identify work tasks that may benefit from exoskeleton use and provided inputs for the design of workplace- or task-specific biomechanical evaluations as well as for exoskeleton design. The work presented in this dissertation may assist in advancing exoskeleton evaluation and design methodology as well as in addressing some of the currently existing gaps in knowledge.