Novel Design of a Rotation Center Auto-Matched Ankle Rehabilitation Exoskeleton With Decoupled Control Capacity

Abstract This article presents a novel ankle rehabilitation exoskeleton for poststroke patients, the rotational center of which can automatically conform to each individual user’s ankle complex, once they wear the exoskeleton; this property always holds regardless of the point at which the exoskeleton is attached to the human shank. This exoskeleton has 2 rotation degree-of-freedoms (DOFs) and is able to provide 2 different rotation patterns via reconfiguration. In the combined-rotation pattern arrangement, the mechanism can generate all three kinds of rotations that the ankle complex is naturally capable of realizing. Among these rotational motions, the adduction/abduction rotation is a coupled motion. This rotation can be further reduced, or eliminated, by minimizing the distance between the lower connection points of the actuated links and the human ankle complex, and vice versa. For the other rotation pattern, a 90-degree arrangement of the side link offers decoupled motion control of the mechanism. Numerical studies reveal that the required rehabilitation workspace for dynamical gait exercises can be achieved with high dexterity, without generating singularities. Further investigations indicate that this mechanism has great potential for rehabilitating poststroke patients of a wide range of heights and weights.