Synthesis of Generalized Spherical Parallel Manipulations for Ankle Rehabilitation

In view of the poor human-machine compatibility of existing ankle rehabilitation robots, which makes it difficult to fully fit the complex motion of the ankle joint, a series of series equivalent fitting models with a higher degree of matching with the actual bone structure of the ankle joint are proposed. In order to meet the functional requirements of this type of equivalent fitting model on the mechanism ontology of rehabilitation robot, a configuration synthesis method of generalized spherical parallel mechanism with series equivalent fitting model is presented. First, the basic components and kinematic pairs of the generalized spherical mechanism are enumerated, and the generalized spherical limb is constructed accordingly. Then, based on the spiral theory, the constraint performance of the single limb and limb combination on the moving platform is analyzed. The combination conditions and principles of limbs are given, the role of different limbs in the mechanism is clarified, and two types of general spherical basic limbs, position limb and orientation limb, are summarized accordingly. Finally, based on the constraint characteristics of the basic limb and the combination conditions, a series of generalized spherical parallel mechanisms suitable for the study of the ankle rehabilitation robot ontology are synthesized. The screw theory proves that the number and nature of degrees of freedom of these of mechanism and the equivalent fitting model of the ankle are consistent, which provides a theoretical basis for the design of such rehabilitation robots.