An Assistive System for Upper Limb Motion Combining Functional Electrical Stimulation and Robotic Exoskeleton

The number of patients with motor dysfunction has increased rapidly over the past decade, in part due to the overall aging of society and the prevalence of neuromuscular disorders. To assist the upper limb in activities of daily livings, we have developed a wearable, portable and hybrid system with multi-degrees of freedom (DOFs). This novel hybrid system combined functional electrical stimulation (FES) with exoskeletons. A two-DOF shoulder exoskeleton, a wearable sleeve with FES electrodes, and a five-DOF hand robotic exoskeleton worked together to facilitate assistance in all of the upper limb joints: shoulder, elbow, wrist, and fingers. A 'divide and rule' strategy was adopted to utilize the relative merits of FES and exoskeletons according to different motion characteristics of upper limb joints. A finite state machine was developed as a high-level controller that issued commands to the real-time embedded controllers. Some functional movements of upper limb could be realised by a sequence of basic movements using the proposed system. The assistance performance of the exoskeleton was evaluated by electromyographic (EMG) signals, and the feasibility of this system was successfully verified by a drinking task.