Design of an upper limb exoskeleton to assist disabled individuals

In order to assist patients with impaired upper limb locomotion in daily life, this article proposes an upper limb exoskeleton which is kinematically compatible with the human upper limb. In addition to the 7DOFs of the free upper limb, two passive DOFs were introduced to support the pectoral girdle protraction/retraction and elevation/depression, and ensure the instantaneous center of shoulder rotation is aligned with human. Furthermore, a Bowden-cable-based actuation was designed to reduce the whole weight and moment of inertia. Subsequently, to evaluate the performance of the proposed exoskeleton, the experiment of discrete point tracking was tested for elbow joint through the designed PID controller. Experimental results indicated that the designed PID control system could achieve stable feedback control. Thus, the proposed exoskeleton could realize the desired position accurately. This exoskeleton achieves the human-robot kinematic compatibility and precise position control, laying the foundation for the next step of continuous trajectory tracking control over the multiply joints.