Lower Limb Exoskeletons, Application-Centric Classifications: A Review

Exoskeletons are a relatively new field of technology used as assistive devices. Since the first development of the exoskeleton in the late 19th century, this field has seen significant advancements, as it has potential in numerous applications. Although this field is rapidly growing, it remains unable to be fully implemented in various applications. It is due to the limitations in the existing technology used to develop the exoskeleton, the lack of standardization, and the rapid growth in the exoskeleton field. To address the existing challenge, this review paper attempts to develop a classification model of lower limb exoskeletons (LLEs), which researchers and engineers can use to understand the relation between various application scenarios and different design aspects while developing an LLE. The classification model has been divided into two levels: application and design aspects of an exoskeleton. In this paper, 53 LLEs have been analyzed and classified into a flexible model, allowing future exoskeletons also to be added. It has also been discussed why each exoskeleton is classified into various categories.