Interactive design and challenges on exoskeleton performance for upper-limb rehabilitation: a comprehensive review

Disabilities due to medical conditions like stroke, paralysis, and frozen shoulder are an increasing issue nowadays and require external rehabilitation. Often, exoskeletons can be a useful aid to carry out rehabilitation. Exoskeletons combine control, sensing, and other automation and display traits from data, bionics, control science, robotics, medicine, and other multidisciplinary areas. The present review aims to study research growth in human movement analysis and methodically compiles advancements in interactive design and challenges in the use of exoskeletons such as human-in-the-loop (HITL) control, human-robot interaction (HRI) using sEMG signals and Machine Learning. This paper encapsulates a comprehensive review of the upper limb exoskeletons which will provide further inputs to physiotherapists and researchers. It is categorized into sections detailing the basic structures of the exoskeletons, and the design principles behind them. Different mechanisms are studied in detail, as well as the challenges faced while designing. It also provides insight into a variety of control strategies and the scope of exoskeleton technology in the future such as 3D printing technology and the application of virtual reality and machine learning technology. Despite these advancements, scope exists for the development of upper limb exoskeletons for paediatric use. The existing exoskeletons are studied and reviewed to draw comparisons between each other. Further discussion is done to modernize the exoskeletons and to note down the key differences that separate them.