Sprained ankle physiotherapy based mechanism synthesis and stiffness analysis of a robotic rehabilitation device

Rehabilitation robotics is a growing field where the study of human movement is one of the key topics. Mechanisms development in terms of analysis and synthesis in the field is relatively new, particularly in the case of parallel robotic mechanisms. This paper presents the background and details of current research into the use of parallel robotic mechanisms for rehabilitation of sprained ankles, and proposes a new device based on a parallel mechanism with a central strut. The paper investigates a new technique in motion analysis of ankle movement which is presented in an orientation image space and in that of a rehabilitation therapy, presents an approach of mechanism synthesis based on this analysis, and develops several parallel mechanisms with a central strut for ankle rehabilitation. This is then related to the analysis of the stiffness effect of the central strut in the platform-type mechanism and the stiffness matrix is decomposed with the part resulting from the central strut which supports ankle rehabilitation. In presenting this new research, the paper relates the study of mechanisms to that of rehabilitation robotics and presents a strong case in the new application of parallel robotic mechanisms.