Position solution of a novel four-DOFs self-aligning exoskeleton mechanism for upper limb rehabilitation

Upper limb rehabilitation exoskeletons are critical equipments for stroke patients with motor function disorders. According to the floating characteristic of human gleno-humeral (GH) joint center, the configuration synthesis for the four-degrees of freedom (4-DOFs) self-aligning exoskeleton mechanisms (SAEMs) is addressed. Based on the configuration priorities of SAEMs, a novel 4-DOFs SAEM is proposed. While the exoskeleton is connected to the upper limb, a human-exoskeleton closed chain with two loops is formed. Subsequently, the kinematic equations of the human-exoskeleton closed chain are established and a position solution method is presented. To evaluate the kinematic performance of the SAEM, the movements of the upper limb in activities of daily living (ADL) are quantified experimentally, on which the joint angle trajectories are generated. Finally, kinematic characteristics of the SAEM in ADL are investigated. Results of the study indicate that the SAEM is suitable for the upper limb rehabilitation and can be used as primary design parameters for the proposed SAEM.