Purpose-centered design of rehabilitation robots: a case study of a hand exoskeleton for assessing spasticity

Hand exoskeletons offer promising solutions for hand function rehabilitation. Despite considerable research on novel exoskeleton technologies and the commercial availability of many hand exoskeletons, most hand exoskeletons can only perform motor training and assistance, rather than treatment or diagnosis of hand diseases. This limitation is also observed in other rehabilitation robots. Designing a rehabilitation robot for medical purposes necessitates the integration of existing technologies, tailored to the symptoms, clinical conditions, and management methods of the target disease. To facilitate such design, this study presents a design strategy for rehabilitation robots that assist in the therapy and assessment of specific diseases. The strategy first systematically gathers prior medical and engineering knowledge on the management of the target disease and clarifies comprehensive design requirements, including medical goals and user needs. Next, modified Quality Function Deployment (QFD) and Theory of Inventive Problem Solving (TRIZ) methods are used to identify the core requirements and the optimal design scheme based on existing technical solutions. Lastly, the optimal design scheme is prototyped, tested, and refined iteratively until the product satisfies the design purpose. As an illustrative case study of this design strategy, the design of a hand exoskeleton for assessing hand spasticity is discussed. This strategy is adaptable for designing hand exoskeletons for other diseases or developing other types of rehabilitation robots, thereby extending the potential of rehabilitation robots in diagnostic and therapeutic applications.