New Concepts of Ankle Rehabilitation Devices—Part I: Theoretical Aspects

The ankle structure holds one of the most important role in the human biomechanics. Due to complexity of everyday activities this joint is the most prone to be injured part of the lower limb. For a complete recovery of the locomotor function, recovery exercises are mandatory. The existent ankle rehabilitation equipments allow only simple rehabilitation exercises, which cannot be used safely without the aid of a therapist. The introduction of robotic physical recovery systems represents a modern alternative to traditional recovery. Actuated devices are advantageous because they allow many types of exercises on same device, and also they accurate measure forces and angular motions. The purpose of this two part paper is to propose two rehabilitation devices, based on different actuating mechanisms. In this first part, structural synthesis, some kinematic and designing aspects of two new ankle rehabilitation devices are presented. The systems are based on the spatial four-bar and Scotch Yoke mechanism, respectively. As requirements for the proposed devices the following aspects have been considered: the systems must be easy to program, financially affordable and they need to offer the two movements (dorsiflexion/plantar flexion and inversion-eversion) required for a complete recovery of the injured ankle.