State-of-the-art robotic devices for ankle rehabilitation: Mechanism and control review

There is an increasing research interest in exploring use of robotic devices for the physical therapy of patients suffering from stroke and spinal cord injuries. Rehabilitation of patients suffering from ankle joint dysfunctions such as drop foot is vital and therefore has called for the development of newer robotic devices. Several robotic orthoses and parallel ankle robots have been developed during the last two decades to augment the conventional ankle physical therapy of patients. A comprehensive review of these robotic ankle rehabilitation devices is presented in this article. Recent developments in the mechanism design, actuation and control are discussed. The study encompasses robotic devices for treadmill and over-ground training as well as platform-based parallel ankle robots. Control strategies for these robotic devices are deliberated in detail with an emphasis on the assist-as-needed training strategies. Experimental evaluations of the mechanism designs and various control strategies of these robotic ankle rehabilitation devices are also presented.