Design of a Parallel Hip Exoskeleton and Its System Implementation Based on Human-Machine Integrated Dynamics

Misalignment between the axes of the human biological joint and the exoskeleton mechanical joint remains an open problem for serial anthropomorphic exoskeletons. To solve this problem, a hip exoskeleton with parallel structure is proposed. With the novel structure, the misalignment between the biological and mechanical joints is eliminated, and therefore the exhausting alignment process of mechanical adjustment before use. In addition, all the hip biological degrees of freedom (DoFs) can be achieved by the proposed exoskeleton, and the hip flexion/extension and abduction/adduction motion can be assisted. To address the problem of coupled actuation introduced by parallel structure, a control method based on human-machine integrated dynamic model is proposed, which enables coordinated control of branch actuators so that assistance can be delivered properly. Moreover, a physical exoskeleton prototype is built. The motion pattern of the proposed exoskeleton is verified in an experiment and the assistive performance is verified by other four experiments. The results demonstrate the kinematic compatibility of the proposed hip exoskeleton and the assistive performance of the controller.